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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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package jsr166y; |
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import java.io.Serializable; |
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import java.util.*; |
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import java.util.concurrent.*; |
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import java.util.concurrent.atomic.*; |
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import sun.misc.Unsafe; |
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import java.lang.reflect.*; |
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import java.util.Collection; |
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import java.util.List; |
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import java.util.RandomAccess; |
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import java.lang.ref.WeakReference; |
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import java.lang.ref.ReferenceQueue; |
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import java.util.concurrent.Callable; |
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import java.util.concurrent.CancellationException; |
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import java.util.concurrent.ExecutionException; |
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import java.util.concurrent.Future; |
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import java.util.concurrent.RejectedExecutionException; |
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import java.util.concurrent.RunnableFuture; |
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import java.util.concurrent.TimeUnit; |
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import java.util.concurrent.TimeoutException; |
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import java.util.concurrent.locks.ReentrantLock; |
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import java.lang.reflect.Constructor; |
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/** |
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* Abstract base class for tasks that run within a {@link |
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* ForkJoinPool}. A ForkJoinTask is a thread-like entity that is much |
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* Abstract base class for tasks that run within a {@link ForkJoinPool}. |
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* A {@code ForkJoinTask} is a thread-like entity that is much |
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* lighter weight than a normal thread. Huge numbers of tasks and |
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* subtasks may be hosted by a small number of actual threads in a |
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* ForkJoinPool, at the price of some usage limitations. |
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* |
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* <p> A "main" ForkJoinTask begins execution when submitted to a |
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* {@link ForkJoinPool}. Once started, it will usually in turn start |
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* other subtasks. As indicated by the name of this class, many |
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* programs using ForkJoinTasks employ only methods <code>fork</code> |
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* and <code>join</code>, or derivatives such as |
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* <code>invokeAll</code>. However, this class also provides a number |
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* of other methods that can come into play in advanced usages, as |
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* well as extension mechanics that allow support of new forms of |
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* fork/join processing. |
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* <p>A "main" {@code ForkJoinTask} begins execution when submitted |
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* to a {@link ForkJoinPool}. Once started, it will usually in turn |
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* start other subtasks. As indicated by the name of this class, |
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* many programs using {@code ForkJoinTask} employ only methods |
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* {@link #fork} and {@link #join}, or derivatives such as {@link |
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* #invokeAll(ForkJoinTask...) invokeAll}. However, this class also |
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* provides a number of other methods that can come into play in |
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* advanced usages, as well as extension mechanics that allow |
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* support of new forms of fork/join processing. |
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* |
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* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}. |
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* The efficiency of {@code ForkJoinTask}s stems from a set of |
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* restrictions (that are only partially statically enforceable) |
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* reflecting their main use as computational tasks calculating pure |
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* functions or operating on purely isolated objects. The primary |
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* coordination mechanisms are {@link #fork}, that arranges |
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* asynchronous execution, and {@link #join}, that doesn't proceed |
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* until the task's result has been computed. Computations should |
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* ideally avoid {@code synchronized} methods or blocks, and should |
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* minimize other blocking synchronization apart from joining other |
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* tasks or using synchronizers such as Phasers that are advertised to |
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* cooperate with fork/join scheduling. Subdividable tasks should also |
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* not perform blocking IO, and should ideally access variables that |
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* are completely independent of those accessed by other running |
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* tasks. These guidelines are loosely enforced by not permitting |
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* checked exceptions such as {@code IOExceptions} to be |
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* thrown. However, computations may still encounter unchecked |
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* exceptions, that are rethrown to callers attempting to join |
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* them. These exceptions may additionally include {@link |
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* RejectedExecutionException} stemming from internal resource |
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* exhaustion, such as failure to allocate internal task |
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* queues. Rethrown exceptions behave in the same way as regular |
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* exceptions, but, when possible, contain stack traces (as displayed |
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* for example using {@code ex.printStackTrace()}) of both the thread |
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* that initiated the computation as well as the thread actually |
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* encountering the exception; minimally only the latter. |
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* |
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* <p>A ForkJoinTask is a lightweight form of {@link Future}. The |
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* efficiency of ForkJoinTasks stems from a set of restrictions (that |
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* are only partially statically enforceable) reflecting their |
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* intended use as computational tasks calculating pure functions or |
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* operating on purely isolated objects. The primary coordination |
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* mechanisms are {@link #fork}, that arranges asynchronous execution, |
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* and {@link #join}, that doesn't proceed until the task's result has |
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* been computed. Computations should avoid <code>synchronized</code> |
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* methods or blocks, and should minimize other blocking |
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* synchronization apart from joining other tasks or using |
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* synchronizers such as Phasers that are advertised to cooperate with |
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* fork/join scheduling. Tasks should also not perform blocking IO, |
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* and should ideally access variables that are completely independent |
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* of those accessed by other running tasks. Minor breaches of these |
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* restrictions, for example using shared output streams, may be |
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* tolerable in practice, but frequent use may result in poor |
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* performance, and the potential to indefinitely stall if the number |
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* of threads not waiting for IO or other external synchronization |
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* becomes exhausted. This usage restriction is in part enforced by |
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* not permitting checked exceptions such as <code>IOExceptions</code> |
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* to be thrown. However, computations may still encounter unchecked |
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* exceptions, that are rethrown to callers attempting join |
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* them. These exceptions may additionally include |
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* RejectedExecutionExceptions stemming from internal resource |
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* exhaustion such as failure to allocate internal task queues. |
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* <p>It is possible to define and use ForkJoinTasks that may block, |
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* but doing do requires three further considerations: (1) Completion |
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* of few if any <em>other</em> tasks should be dependent on a task |
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* that blocks on external synchronization or IO. Event-style async |
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* tasks that are never joined (for example, those subclassing {@link |
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* CountedCompleter}) often fall into this category. (2) To minimize |
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* resource impact, tasks should be small; ideally performing only the |
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* (possibly) blocking action. (3) Unless the {@link |
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* ForkJoinPool.ManagedBlocker} API is used, or the number of possibly |
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* blocked tasks is known to be less than the pool's {@link |
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* ForkJoinPool#getParallelism} level, the pool cannot guarantee that |
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* enough threads will be available to ensure progress or good |
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* performance. |
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* |
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* <p>The primary method for awaiting completion and extracting |
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* results of a task is {@link #join}, but there are several variants: |
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* The {@link Future#get} methods support interruptible and/or timed |
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* waits for completion and report results using <code>Future</code> |
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* conventions. Method {@link #helpJoin} enables callers to actively |
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* execute other tasks while awaiting joins, which is sometimes more |
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* efficient but only applies when all subtasks are known to be |
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* strictly tree-structured. Method {@link #invoke} is semantically |
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* equivalent to <code>fork(); join()</code> but always attempts to |
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* begin execution in the current thread. The "<em>quiet</em>" forms |
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* of these methods do not extract results or report exceptions. These |
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* waits for completion and report results using {@code Future} |
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* conventions. Method {@link #invoke} is semantically |
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* equivalent to {@code fork(); join()} but always attempts to begin |
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* execution in the current thread. The "<em>quiet</em>" forms of |
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* these methods do not extract results or report exceptions. These |
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* may be useful when a set of tasks are being executed, and you need |
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* to delay processing of results or exceptions until all complete. |
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* Method <code>invokeAll</code> (available in multiple versions) |
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* Method {@code invokeAll} (available in multiple versions) |
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* performs the most common form of parallel invocation: forking a set |
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* of tasks and joining them all. |
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* |
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* <p> The ForkJoinTask class is not usually directly subclassed. |
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* <p>In the most typical usages, a fork-join pair act like a call |
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* (fork) and return (join) from a parallel recursive function. As is |
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* the case with other forms of recursive calls, returns (joins) |
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* should be performed innermost-first. For example, {@code a.fork(); |
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* b.fork(); b.join(); a.join();} is likely to be substantially more |
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* efficient than joining {@code a} before {@code b}. |
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* |
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* <p>The execution status of tasks may be queried at several levels |
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* of detail: {@link #isDone} is true if a task completed in any way |
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* (including the case where a task was cancelled without executing); |
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* {@link #isCompletedNormally} is true if a task completed without |
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* cancellation or encountering an exception; {@link #isCancelled} is |
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* true if the task was cancelled (in which case {@link #getException} |
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* returns a {@link java.util.concurrent.CancellationException}); and |
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* {@link #isCompletedAbnormally} is true if a task was either |
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* cancelled or encountered an exception, in which case {@link |
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* #getException} will return either the encountered exception or |
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* {@link java.util.concurrent.CancellationException}. |
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* |
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* <p>The ForkJoinTask class is not usually directly subclassed. |
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* Instead, you subclass one of the abstract classes that support a |
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* particular style of fork/join processing. Normally, a concrete |
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* ForkJoinTask subclass declares fields comprising its parameters, |
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* established in a constructor, and then defines a <code>compute</code> |
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* method that somehow uses the control methods supplied by this base |
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* class. While these methods have <code>public</code> access (to allow |
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* instances of different task subclasses to call each others |
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* methods), some of them may only be called from within other |
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* ForkJoinTasks. Attempts to invoke them in other contexts result in |
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* exceptions or errors possibly including ClassCastException. |
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* particular style of fork/join processing, typically {@link |
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* RecursiveAction} for most computations that do not return results, |
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* {@link RecursiveTask} for those that do, and {@link |
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* CountedCompleter} for those in which completed actions trigger |
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* other actions. Normally, a concrete ForkJoinTask subclass declares |
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* fields comprising its parameters, established in a constructor, and |
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* then defines a {@code compute} method that somehow uses the control |
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* methods supplied by this base class. While these methods have |
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* {@code public} access (to allow instances of different task |
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* subclasses to call each other's methods), some of them may only be |
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* called from within other ForkJoinTasks (as may be determined using |
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* method {@link #inForkJoinPool}). Attempts to invoke them in other |
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* contexts result in exceptions or errors, possibly including {@code |
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* ClassCastException}. |
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* |
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* <p>Method {@link #join} and its variants are appropriate for use |
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* only when completion dependencies are acyclic; that is, the |
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* parallel computation can be described as a directed acyclic graph |
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* (DAG). Otherwise, executions may encounter a form of deadlock as |
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* tasks cyclically wait for each other. However, this framework |
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* supports other methods and techniques (for example the use of |
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* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that |
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* may be of use in constructing custom subclasses for problems that |
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* are not statically structured as DAGs. To support such usages a |
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* ForkJoinTask may be atomically <em>tagged</em> with a {@code short} |
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* value using {@link #setForkJoinTaskTag} or {@link |
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* #compareAndSetForkJoinTaskTag} and checked using {@link |
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* #getForkJoinTaskTag}. The ForkJoinTask implementation does not use |
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* these {@code protected} methods or tags for any purpose, but they |
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* may be of use in the construction of specialized subclasses. For |
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* example, parallel graph traversals can use the supplied methods to |
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* avoid revisiting nodes/tasks that have already been processed. |
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* (Method names for tagging are bulky in part to encourage definition |
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* of methods that reflect their usage patterns.) |
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* |
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* <p>Most base support methods are <code>final</code> because their |
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* implementations are intrinsically tied to the underlying |
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* lightweight task scheduling framework, and so cannot be overridden. |
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* Developers creating new basic styles of fork/join processing should |
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* minimally implement <code>protected</code> methods |
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* <code>exec</code>, <code>setRawResult</code>, and |
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* <code>getRawResult</code>, while also introducing an abstract |
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* computational method that can be implemented in its subclasses, |
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* possibly relying on other <code>protected</code> methods provided |
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* by this class. |
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* <p>Most base support methods are {@code final}, to prevent |
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* overriding of implementations that are intrinsically tied to the |
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* underlying lightweight task scheduling framework. Developers |
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* creating new basic styles of fork/join processing should minimally |
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* implement {@code protected} methods {@link #exec}, {@link |
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* #setRawResult}, and {@link #getRawResult}, while also introducing |
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* an abstract computational method that can be implemented in its |
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* subclasses, possibly relying on other {@code protected} methods |
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* provided by this class. |
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* |
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* <p>ForkJoinTasks should perform relatively small amounts of |
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* computations, othewise splitting into smaller tasks. As a very |
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* rough rule of thumb, a task should perform more than 100 and less |
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* than 10000 basic computational steps. If tasks are too big, then |
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* parellelism cannot improve throughput. If too small, then memory |
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* and internal task maintenance overhead may overwhelm processing. |
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* computation. Large tasks should be split into smaller subtasks, |
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* usually via recursive decomposition. As a very rough rule of thumb, |
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* a task should perform more than 100 and less than 10000 basic |
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* computational steps, and should avoid indefinite looping. If tasks |
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* are too big, then parallelism cannot improve throughput. If too |
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* small, then memory and internal task maintenance overhead may |
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* overwhelm processing. |
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* |
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* <p>ForkJoinTasks are <code>Serializable</code>, which enables them |
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* to be used in extensions such as remote execution frameworks. It is |
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* in general sensible to serialize tasks only before or after, but |
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* not during execution. Serialization is not relied on during |
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* execution itself. |
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* <p>This class provides {@code adapt} methods for {@link Runnable} |
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* and {@link Callable}, that may be of use when mixing execution of |
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* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are |
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* of this form, consider using a pool constructed in <em>asyncMode</em>. |
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* |
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* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
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* used in extensions such as remote execution frameworks. It is |
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* sensible to serialize tasks only before or after, but not during, |
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* execution. Serialization is not relied on during execution itself. |
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* |
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* @since 1.7 |
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* @author Doug Lea |
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*/ |
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public abstract class ForkJoinTask<V> implements Future<V>, Serializable { |
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|
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/** |
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* Run control status bits packed into a single int to minimize |
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* footprint and to ensure atomicity (via CAS). Status is |
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* initially zero, and takes on nonnegative values until |
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* completed, upon which status holds COMPLETED. CANCELLED, or |
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* EXCEPTIONAL, which use the top 3 bits. Tasks undergoing |
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* blocking waits by other threads have SIGNAL_MASK bits set -- |
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* bit 15 for external (nonFJ) waits, and the rest a count of |
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* waiting FJ threads. (This representation relies on |
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* ForkJoinPool max thread limits). Completion of a stolen task |
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* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even |
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* though suboptimal for some purposes, we use basic builtin |
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* wait/notify to take advantage of "monitor inflation" in JVMs |
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* that we would otherwise need to emulate to avoid adding further |
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* per-task bookkeeping overhead. Note that bits 16-28 are |
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* currently unused. Also value 0x80000000 is available as spare |
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* completion value. |
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*/ |
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volatile int status; // accessed directy by pool and workers |
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|
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static final int COMPLETION_MASK = 0xe0000000; |
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static final int NORMAL = 0xe0000000; // == mask |
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static final int CANCELLED = 0xc0000000; |
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static final int EXCEPTIONAL = 0xa0000000; |
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static final int SIGNAL_MASK = 0x0000ffff; |
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static final int INTERNAL_SIGNAL_MASK = 0x00007fff; |
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static final int EXTERNAL_SIGNAL = 0x00008000; // top bit of low word |
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|
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/** |
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* Table of exceptions thrown by tasks, to enable reporting by |
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* callers. Because exceptions are rare, we don't directly keep |
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* them with task objects, but instead us a weak ref table. Note |
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* that cancellation exceptions don't appear in the table, but are |
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* instead recorded as status values. |
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* Todo: Use ConcurrentReferenceHashMap |
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*/ |
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static final Map<ForkJoinTask<?>, Throwable> exceptionMap = |
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Collections.synchronizedMap |
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(new WeakHashMap<ForkJoinTask<?>, Throwable>()); |
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|
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// within-package utilities |
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|
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/** |
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* Get current worker thread, or null if not a worker thread |
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*/ |
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static ForkJoinWorkerThread getWorker() { |
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Thread t = Thread.currentThread(); |
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return ((t instanceof ForkJoinWorkerThread)? |
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(ForkJoinWorkerThread)t : null); |
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} |
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|
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final boolean casStatus(int cmp, int val) { |
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return _unsafe.compareAndSwapInt(this, statusOffset, cmp, val); |
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} |
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|
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/** |
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* Workaround for not being able to rethrow unchecked exceptions. |
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*/ |
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static void rethrowException(Throwable ex) { |
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if (ex != null) |
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_unsafe.throwException(ex); |
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} |
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|
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// Setting completion status |
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/* |
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* See the internal documentation of class ForkJoinPool for a |
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* general implementation overview. ForkJoinTasks are mainly |
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* responsible for maintaining their "status" field amidst relays |
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* to methods in ForkJoinWorkerThread and ForkJoinPool. |
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* |
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* The methods of this class are more-or-less layered into |
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* (1) basic status maintenance |
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* (2) execution and awaiting completion |
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* (3) user-level methods that additionally report results. |
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* This is sometimes hard to see because this file orders exported |
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* methods in a way that flows well in javadocs. |
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*/ |
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|
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/* |
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* The status field holds run control status bits packed into a |
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* single int to minimize footprint and to ensure atomicity (via |
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* CAS). Status is initially zero, and takes on nonnegative |
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* values until completed, upon which status (anded with |
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* DONE_MASK) holds value NORMAL, CANCELLED, or EXCEPTIONAL. Tasks |
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* undergoing blocking waits by other threads have the SIGNAL bit |
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* set. Completion of a stolen task with SIGNAL set awakens any |
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* waiters via notifyAll. Even though suboptimal for some |
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* purposes, we use basic builtin wait/notify to take advantage of |
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* "monitor inflation" in JVMs that we would otherwise need to |
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* emulate to avoid adding further per-task bookkeeping overhead. |
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* We want these monitors to be "fat", i.e., not use biasing or |
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* thin-lock techniques, so use some odd coding idioms that tend |
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> |
* to avoid them, mainly by arranging that every synchronized |
217 |
> |
* block performs a wait, notifyAll or both. |
218 |
> |
* |
219 |
> |
* These control bits occupy only (some of) the upper half (16 |
220 |
> |
* bits) of status field. The lower bits are used for user-defined |
221 |
> |
* tags. |
222 |
> |
*/ |
223 |
> |
|
224 |
> |
/** The run status of this task */ |
225 |
> |
volatile int status; // accessed directly by pool and workers |
226 |
> |
static final int DONE_MASK = 0xf0000000; // mask out non-completion bits |
227 |
> |
static final int NORMAL = 0xf0000000; // must be negative |
228 |
> |
static final int CANCELLED = 0xc0000000; // must be < NORMAL |
229 |
> |
static final int EXCEPTIONAL = 0x80000000; // must be < CANCELLED |
230 |
> |
static final int SIGNAL = 0x00010000; // must be >= 1 << 16 |
231 |
> |
static final int SMASK = 0x0000ffff; // short bits for tags |
232 |
|
|
233 |
|
/** |
234 |
< |
* Mark completion and wake up threads waiting to join this task. |
234 |
> |
* Marks completion and wakes up threads waiting to join this |
235 |
> |
* task. |
236 |
> |
* |
237 |
|
* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL |
238 |
+ |
* @return completion status on exit |
239 |
|
*/ |
240 |
< |
final void setCompletion(int completion) { |
241 |
< |
ForkJoinPool pool = getPool(); |
242 |
< |
if (pool != null) { |
243 |
< |
int s; // Clear signal bits while setting completion status |
244 |
< |
do;while ((s = status) >= 0 && !casStatus(s, completion)); |
245 |
< |
|
246 |
< |
if ((s & SIGNAL_MASK) != 0) { |
247 |
< |
if ((s &= INTERNAL_SIGNAL_MASK) != 0) |
190 |
< |
pool.updateRunningCount(s); |
191 |
< |
synchronized(this) { notifyAll(); } |
240 |
> |
private int setCompletion(int completion) { |
241 |
> |
for (int s;;) { |
242 |
> |
if ((s = status) < 0) |
243 |
> |
return s; |
244 |
> |
if (U.compareAndSwapInt(this, STATUS, s, s | completion)) { |
245 |
> |
if ((s >>> 16) != 0) |
246 |
> |
synchronized (this) { notifyAll(); } |
247 |
> |
return completion; |
248 |
|
} |
249 |
|
} |
194 |
– |
else |
195 |
– |
externallySetCompletion(completion); |
196 |
– |
} |
197 |
– |
|
198 |
– |
/** |
199 |
– |
* Version of setCompletion for non-FJ threads. Leaves signal |
200 |
– |
* bits for unblocked threads to adjust, and always notifies. |
201 |
– |
*/ |
202 |
– |
private void externallySetCompletion(int completion) { |
203 |
– |
int s; |
204 |
– |
do;while ((s = status) >= 0 && |
205 |
– |
!casStatus(s, (s & SIGNAL_MASK) | completion)); |
206 |
– |
synchronized(this) { notifyAll(); } |
207 |
– |
} |
208 |
– |
|
209 |
– |
/** |
210 |
– |
* Sets status to indicate normal completion |
211 |
– |
*/ |
212 |
– |
final void setNormalCompletion() { |
213 |
– |
// Try typical fast case -- single CAS, no signal, not already done. |
214 |
– |
// Manually expand casStatus to improve chances of inlining it |
215 |
– |
if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL)) |
216 |
– |
setCompletion(NORMAL); |
250 |
|
} |
251 |
|
|
219 |
– |
// internal waiting and notification |
220 |
– |
|
252 |
|
/** |
253 |
< |
* Performs the actual monitor wait for awaitDone |
253 |
> |
* Primary execution method for stolen tasks. Unless done, calls |
254 |
> |
* exec and records status if completed, but doesn't wait for |
255 |
> |
* completion otherwise. |
256 |
> |
* |
257 |
> |
* @return status on exit from this method |
258 |
|
*/ |
259 |
< |
private void doAwaitDone() { |
260 |
< |
// Minimize lock bias and in/de-flation effects by maximizing |
261 |
< |
// chances of waiting inside sync |
262 |
< |
try { |
263 |
< |
while (status >= 0) |
264 |
< |
synchronized(this) { if (status >= 0) wait(); } |
265 |
< |
} catch (InterruptedException ie) { |
266 |
< |
onInterruptedWait(); |
259 |
> |
final int doExec() { |
260 |
> |
int s; boolean completed; |
261 |
> |
if ((s = status) >= 0) { |
262 |
> |
try { |
263 |
> |
completed = exec(); |
264 |
> |
} catch (Throwable rex) { |
265 |
> |
return setExceptionalCompletion(rex); |
266 |
> |
} |
267 |
> |
if (completed) |
268 |
> |
s = setCompletion(NORMAL); |
269 |
|
} |
270 |
+ |
return s; |
271 |
|
} |
272 |
|
|
273 |
|
/** |
274 |
< |
* Performs the actual monitor wait for awaitDone |
274 |
> |
* Tries to set SIGNAL status unless already completed. Used by |
275 |
> |
* ForkJoinPool. Other variants are directly incorporated into |
276 |
> |
* externalAwaitDone etc. |
277 |
> |
* |
278 |
> |
* @return true if successful |
279 |
|
*/ |
280 |
< |
private void doAwaitDone(long startTime, long nanos) { |
281 |
< |
synchronized(this) { |
282 |
< |
try { |
241 |
< |
while (status >= 0) { |
242 |
< |
long nt = nanos - System.nanoTime() - startTime; |
243 |
< |
if (nt <= 0) |
244 |
< |
break; |
245 |
< |
wait(nt / 1000000, (int)(nt % 1000000)); |
246 |
< |
} |
247 |
< |
} catch (InterruptedException ie) { |
248 |
< |
onInterruptedWait(); |
249 |
< |
} |
250 |
< |
} |
280 |
> |
final boolean trySetSignal() { |
281 |
> |
int s = status; |
282 |
> |
return s >= 0 && U.compareAndSwapInt(this, STATUS, s, s | SIGNAL); |
283 |
|
} |
284 |
|
|
253 |
– |
// Awaiting completion |
254 |
– |
|
285 |
|
/** |
286 |
< |
* Sets status to indicate there is joiner, then waits for join, |
287 |
< |
* surrounded with pool notifications. |
258 |
< |
* @return status upon exit |
286 |
> |
* Blocks a non-worker-thread until completion. |
287 |
> |
* @return status upon completion |
288 |
|
*/ |
289 |
< |
private int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) { |
290 |
< |
ForkJoinPool pool = w == null? null : w.pool; |
289 |
> |
private int externalAwaitDone() { |
290 |
> |
boolean interrupted = false; |
291 |
|
int s; |
292 |
|
while ((s = status) >= 0) { |
293 |
< |
if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) { |
294 |
< |
if (pool == null || !pool.preJoin(this, maintainParallelism)) |
295 |
< |
doAwaitDone(); |
296 |
< |
if (((s = status) & INTERNAL_SIGNAL_MASK) != 0) |
297 |
< |
adjustPoolCountsOnUnblock(pool); |
298 |
< |
break; |
293 |
> |
if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) { |
294 |
> |
synchronized (this) { |
295 |
> |
if (status >= 0) { |
296 |
> |
try { |
297 |
> |
wait(); |
298 |
> |
} catch (InterruptedException ie) { |
299 |
> |
interrupted = true; |
300 |
> |
} |
301 |
> |
} |
302 |
> |
else |
303 |
> |
notifyAll(); |
304 |
> |
} |
305 |
|
} |
306 |
|
} |
307 |
+ |
if (interrupted) |
308 |
+ |
Thread.currentThread().interrupt(); |
309 |
|
return s; |
310 |
|
} |
311 |
|
|
312 |
|
/** |
313 |
< |
* Timed version of awaitDone |
277 |
< |
* @return status upon exit |
313 |
> |
* Blocks a non-worker-thread until completion or interruption. |
314 |
|
*/ |
315 |
< |
private int awaitDone(ForkJoinWorkerThread w, long nanos) { |
280 |
< |
ForkJoinPool pool = w == null? null : w.pool; |
315 |
> |
private int externalInterruptibleAwaitDone() throws InterruptedException { |
316 |
|
int s; |
317 |
+ |
if (Thread.interrupted()) |
318 |
+ |
throw new InterruptedException(); |
319 |
|
while ((s = status) >= 0) { |
320 |
< |
if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) { |
321 |
< |
long startTime = System.nanoTime(); |
322 |
< |
if (pool == null || !pool.preJoin(this, false)) |
323 |
< |
doAwaitDone(startTime, nanos); |
324 |
< |
if ((s = status) >= 0) { |
325 |
< |
adjustPoolCountsOnCancelledWait(pool); |
289 |
< |
s = status; |
320 |
> |
if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) { |
321 |
> |
synchronized (this) { |
322 |
> |
if (status >= 0) |
323 |
> |
wait(); |
324 |
> |
else |
325 |
> |
notifyAll(); |
326 |
|
} |
291 |
– |
if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0) |
292 |
– |
adjustPoolCountsOnUnblock(pool); |
293 |
– |
break; |
327 |
|
} |
328 |
|
} |
329 |
|
return s; |
330 |
|
} |
331 |
|
|
332 |
|
/** |
333 |
< |
* Notify pool that thread is unblocked. Called by signalled |
334 |
< |
* threads when woken by non-FJ threads (which is atypical). |
333 |
> |
* Implementation for join, get, quietlyJoin. Directly handles |
334 |
> |
* only cases of already-completed, external wait, and |
335 |
> |
* unfork+exec. Others are relayed to ForkJoinPool.awaitJoin. |
336 |
> |
* |
337 |
> |
* @return status upon completion |
338 |
|
*/ |
339 |
< |
private void adjustPoolCountsOnUnblock(ForkJoinPool pool) { |
340 |
< |
int s; |
341 |
< |
do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK)); |
342 |
< |
if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0) |
343 |
< |
pool.updateRunningCount(s); |
339 |
> |
private int doJoin() { |
340 |
> |
int s; Thread t; ForkJoinWorkerThread wt; ForkJoinPool.WorkQueue w; |
341 |
> |
if ((s = status) >= 0) { |
342 |
> |
if (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)) { |
343 |
> |
if (!(w = (wt = (ForkJoinWorkerThread)t).workQueue). |
344 |
> |
tryUnpush(this) || (s = doExec()) >= 0) |
345 |
> |
s = wt.pool.awaitJoin(w, this); |
346 |
> |
} |
347 |
> |
else |
348 |
> |
s = externalAwaitDone(); |
349 |
> |
} |
350 |
> |
return s; |
351 |
|
} |
352 |
|
|
353 |
|
/** |
354 |
< |
* Notify pool to adjust counts on cancelled or timed out wait |
354 |
> |
* Implementation for invoke, quietlyInvoke. |
355 |
> |
* |
356 |
> |
* @return status upon completion |
357 |
|
*/ |
358 |
< |
private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) { |
359 |
< |
if (pool != null) { |
360 |
< |
int s; |
361 |
< |
while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) { |
362 |
< |
if (casStatus(s, s - 1)) { |
363 |
< |
pool.updateRunningCount(1); |
364 |
< |
break; |
365 |
< |
} |
321 |
< |
} |
358 |
> |
private int doInvoke() { |
359 |
> |
int s; Thread t; ForkJoinWorkerThread wt; |
360 |
> |
if ((s = doExec()) >= 0) { |
361 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
362 |
> |
s = (wt = (ForkJoinWorkerThread)t).pool.awaitJoin(wt.workQueue, |
363 |
> |
this); |
364 |
> |
else |
365 |
> |
s = externalAwaitDone(); |
366 |
|
} |
367 |
+ |
return s; |
368 |
|
} |
369 |
|
|
370 |
+ |
// Exception table support |
371 |
+ |
|
372 |
|
/** |
373 |
< |
* Handle interruptions during waits. |
373 |
> |
* Table of exceptions thrown by tasks, to enable reporting by |
374 |
> |
* callers. Because exceptions are rare, we don't directly keep |
375 |
> |
* them with task objects, but instead use a weak ref table. Note |
376 |
> |
* that cancellation exceptions don't appear in the table, but are |
377 |
> |
* instead recorded as status values. |
378 |
> |
* |
379 |
> |
* Note: These statics are initialized below in static block. |
380 |
|
*/ |
381 |
< |
private void onInterruptedWait() { |
382 |
< |
ForkJoinWorkerThread w = getWorker(); |
383 |
< |
if (w == null) |
331 |
< |
Thread.currentThread().interrupt(); // re-interrupt |
332 |
< |
else if (w.isTerminating()) |
333 |
< |
cancelIgnoringExceptions(); |
334 |
< |
// else if FJworker, ignore interrupt |
335 |
< |
} |
381 |
> |
private static final ExceptionNode[] exceptionTable; |
382 |
> |
private static final ReentrantLock exceptionTableLock; |
383 |
> |
private static final ReferenceQueue<Object> exceptionTableRefQueue; |
384 |
|
|
385 |
< |
// Recording and reporting exceptions |
385 |
> |
/** |
386 |
> |
* Fixed capacity for exceptionTable. |
387 |
> |
*/ |
388 |
> |
private static final int EXCEPTION_MAP_CAPACITY = 32; |
389 |
|
|
390 |
< |
private void setDoneExceptionally(Throwable rex) { |
391 |
< |
exceptionMap.put(this, rex); |
392 |
< |
setCompletion(EXCEPTIONAL); |
390 |
> |
/** |
391 |
> |
* Key-value nodes for exception table. The chained hash table |
392 |
> |
* uses identity comparisons, full locking, and weak references |
393 |
> |
* for keys. The table has a fixed capacity because it only |
394 |
> |
* maintains task exceptions long enough for joiners to access |
395 |
> |
* them, so should never become very large for sustained |
396 |
> |
* periods. However, since we do not know when the last joiner |
397 |
> |
* completes, we must use weak references and expunge them. We do |
398 |
> |
* so on each operation (hence full locking). Also, some thread in |
399 |
> |
* any ForkJoinPool will call helpExpungeStaleExceptions when its |
400 |
> |
* pool becomes isQuiescent. |
401 |
> |
*/ |
402 |
> |
static final class ExceptionNode extends WeakReference<ForkJoinTask<?>> { |
403 |
> |
final Throwable ex; |
404 |
> |
ExceptionNode next; |
405 |
> |
final long thrower; // use id not ref to avoid weak cycles |
406 |
> |
ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) { |
407 |
> |
super(task, exceptionTableRefQueue); |
408 |
> |
this.ex = ex; |
409 |
> |
this.next = next; |
410 |
> |
this.thrower = Thread.currentThread().getId(); |
411 |
> |
} |
412 |
|
} |
413 |
|
|
414 |
|
/** |
415 |
< |
* Throws the exception associated with status s; |
416 |
< |
* @throws the exception |
415 |
> |
* Records exception and sets status. |
416 |
> |
* |
417 |
> |
* @return status on exit |
418 |
|
*/ |
419 |
< |
private void reportException(int s) { |
420 |
< |
if ((s &= COMPLETION_MASK) < NORMAL) { |
421 |
< |
if (s == CANCELLED) |
422 |
< |
throw new CancellationException(); |
423 |
< |
else |
424 |
< |
rethrowException(exceptionMap.get(this)); |
419 |
> |
final int recordExceptionalCompletion(Throwable ex) { |
420 |
> |
int s; |
421 |
> |
if ((s = status) >= 0) { |
422 |
> |
int h = System.identityHashCode(this); |
423 |
> |
final ReentrantLock lock = exceptionTableLock; |
424 |
> |
lock.lock(); |
425 |
> |
try { |
426 |
> |
expungeStaleExceptions(); |
427 |
> |
ExceptionNode[] t = exceptionTable; |
428 |
> |
int i = h & (t.length - 1); |
429 |
> |
for (ExceptionNode e = t[i]; ; e = e.next) { |
430 |
> |
if (e == null) { |
431 |
> |
t[i] = new ExceptionNode(this, ex, t[i]); |
432 |
> |
break; |
433 |
> |
} |
434 |
> |
if (e.get() == this) // already present |
435 |
> |
break; |
436 |
> |
} |
437 |
> |
} finally { |
438 |
> |
lock.unlock(); |
439 |
> |
} |
440 |
> |
s = setCompletion(EXCEPTIONAL); |
441 |
|
} |
442 |
+ |
return s; |
443 |
|
} |
444 |
|
|
445 |
|
/** |
446 |
< |
* Returns result or throws exception using j.u.c.Future conventions |
447 |
< |
* Only call when isDone known to be true. |
446 |
> |
* Records exception and possibly propagates |
447 |
> |
* |
448 |
> |
* @return status on exit |
449 |
|
*/ |
450 |
< |
private V reportFutureResult() |
451 |
< |
throws ExecutionException, InterruptedException { |
452 |
< |
int s = status & COMPLETION_MASK; |
453 |
< |
if (s < NORMAL) { |
454 |
< |
Throwable ex; |
366 |
< |
if (s == CANCELLED) |
367 |
< |
throw new CancellationException(); |
368 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
369 |
< |
throw new ExecutionException(ex); |
370 |
< |
if (Thread.interrupted()) |
371 |
< |
throw new InterruptedException(); |
372 |
< |
} |
373 |
< |
return getRawResult(); |
450 |
> |
private int setExceptionalCompletion(Throwable ex) { |
451 |
> |
int s = recordExceptionalCompletion(ex); |
452 |
> |
if ((s & DONE_MASK) == EXCEPTIONAL) |
453 |
> |
internalPropagateException(ex); |
454 |
> |
return s; |
455 |
|
} |
456 |
|
|
457 |
|
/** |
458 |
< |
* Returns result or throws exception using j.u.c.Future conventions |
378 |
< |
* with timeouts |
458 |
> |
* Hook for exception propagation support for tasks with completers. |
459 |
|
*/ |
460 |
< |
private V reportTimedFutureResult() |
381 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
382 |
< |
Throwable ex; |
383 |
< |
int s = status & COMPLETION_MASK; |
384 |
< |
if (s == NORMAL) |
385 |
< |
return getRawResult(); |
386 |
< |
if (s == CANCELLED) |
387 |
< |
throw new CancellationException(); |
388 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
389 |
< |
throw new ExecutionException(ex); |
390 |
< |
if (Thread.interrupted()) |
391 |
< |
throw new InterruptedException(); |
392 |
< |
throw new TimeoutException(); |
460 |
> |
void internalPropagateException(Throwable ex) { |
461 |
|
} |
462 |
|
|
463 |
< |
// internal execution methods |
463 |
> |
/** |
464 |
> |
* Cancels, ignoring any exceptions thrown by cancel. Used during |
465 |
> |
* worker and pool shutdown. Cancel is spec'ed not to throw any |
466 |
> |
* exceptions, but if it does anyway, we have no recourse during |
467 |
> |
* shutdown, so guard against this case. |
468 |
> |
*/ |
469 |
> |
static final void cancelIgnoringExceptions(ForkJoinTask<?> t) { |
470 |
> |
if (t != null && t.status >= 0) { |
471 |
> |
try { |
472 |
> |
t.cancel(false); |
473 |
> |
} catch (Throwable ignore) { |
474 |
> |
} |
475 |
> |
} |
476 |
> |
} |
477 |
|
|
478 |
|
/** |
479 |
< |
* Calls exec, recording completion, and rethrowing exception if |
399 |
< |
* encountered. Caller should normally check status before calling |
400 |
< |
* @return true if completed normally |
479 |
> |
* Removes exception node and clears status |
480 |
|
*/ |
481 |
< |
private boolean tryExec() { |
482 |
< |
try { // try block must contain only call to exec |
483 |
< |
if (!exec()) |
484 |
< |
return false; |
485 |
< |
} catch (Throwable rex) { |
486 |
< |
setDoneExceptionally(rex); |
487 |
< |
rethrowException(rex); |
488 |
< |
return false; // not reached |
481 |
> |
private void clearExceptionalCompletion() { |
482 |
> |
int h = System.identityHashCode(this); |
483 |
> |
final ReentrantLock lock = exceptionTableLock; |
484 |
> |
lock.lock(); |
485 |
> |
try { |
486 |
> |
ExceptionNode[] t = exceptionTable; |
487 |
> |
int i = h & (t.length - 1); |
488 |
> |
ExceptionNode e = t[i]; |
489 |
> |
ExceptionNode pred = null; |
490 |
> |
while (e != null) { |
491 |
> |
ExceptionNode next = e.next; |
492 |
> |
if (e.get() == this) { |
493 |
> |
if (pred == null) |
494 |
> |
t[i] = next; |
495 |
> |
else |
496 |
> |
pred.next = next; |
497 |
> |
break; |
498 |
> |
} |
499 |
> |
pred = e; |
500 |
> |
e = next; |
501 |
> |
} |
502 |
> |
expungeStaleExceptions(); |
503 |
> |
status = 0; |
504 |
> |
} finally { |
505 |
> |
lock.unlock(); |
506 |
|
} |
411 |
– |
setNormalCompletion(); |
412 |
– |
return true; |
507 |
|
} |
508 |
|
|
509 |
|
/** |
510 |
< |
* Main execution method used by worker threads. Invokes |
511 |
< |
* base computation unless already complete |
510 |
> |
* Returns a rethrowable exception for the given task, if |
511 |
> |
* available. To provide accurate stack traces, if the exception |
512 |
> |
* was not thrown by the current thread, we try to create a new |
513 |
> |
* exception of the same type as the one thrown, but with the |
514 |
> |
* recorded exception as its cause. If there is no such |
515 |
> |
* constructor, we instead try to use a no-arg constructor, |
516 |
> |
* followed by initCause, to the same effect. If none of these |
517 |
> |
* apply, or any fail due to other exceptions, we return the |
518 |
> |
* recorded exception, which is still correct, although it may |
519 |
> |
* contain a misleading stack trace. |
520 |
> |
* |
521 |
> |
* @return the exception, or null if none |
522 |
|
*/ |
523 |
< |
final void quietlyExec() { |
524 |
< |
if (status >= 0) { |
523 |
> |
private Throwable getThrowableException() { |
524 |
> |
if ((status & DONE_MASK) != EXCEPTIONAL) |
525 |
> |
return null; |
526 |
> |
int h = System.identityHashCode(this); |
527 |
> |
ExceptionNode e; |
528 |
> |
final ReentrantLock lock = exceptionTableLock; |
529 |
> |
lock.lock(); |
530 |
> |
try { |
531 |
> |
expungeStaleExceptions(); |
532 |
> |
ExceptionNode[] t = exceptionTable; |
533 |
> |
e = t[h & (t.length - 1)]; |
534 |
> |
while (e != null && e.get() != this) |
535 |
> |
e = e.next; |
536 |
> |
} finally { |
537 |
> |
lock.unlock(); |
538 |
> |
} |
539 |
> |
Throwable ex; |
540 |
> |
if (e == null || (ex = e.ex) == null) |
541 |
> |
return null; |
542 |
> |
if (false && e.thrower != Thread.currentThread().getId()) { |
543 |
> |
Class<? extends Throwable> ec = ex.getClass(); |
544 |
|
try { |
545 |
< |
if (!exec()) |
546 |
< |
return; |
547 |
< |
} catch(Throwable rex) { |
548 |
< |
setDoneExceptionally(rex); |
549 |
< |
return; |
545 |
> |
Constructor<?> noArgCtor = null; |
546 |
> |
Constructor<?>[] cs = ec.getConstructors();// public ctors only |
547 |
> |
for (int i = 0; i < cs.length; ++i) { |
548 |
> |
Constructor<?> c = cs[i]; |
549 |
> |
Class<?>[] ps = c.getParameterTypes(); |
550 |
> |
if (ps.length == 0) |
551 |
> |
noArgCtor = c; |
552 |
> |
else if (ps.length == 1 && ps[0] == Throwable.class) |
553 |
> |
return (Throwable)(c.newInstance(ex)); |
554 |
> |
} |
555 |
> |
if (noArgCtor != null) { |
556 |
> |
Throwable wx = (Throwable)(noArgCtor.newInstance()); |
557 |
> |
wx.initCause(ex); |
558 |
> |
return wx; |
559 |
> |
} |
560 |
> |
} catch (Exception ignore) { |
561 |
|
} |
428 |
– |
setNormalCompletion(); |
562 |
|
} |
563 |
+ |
return ex; |
564 |
|
} |
565 |
|
|
566 |
|
/** |
567 |
< |
* Calls exec, recording but not rethrowing exception |
434 |
< |
* Caller should normally check status before calling |
435 |
< |
* @return true if completed normally |
567 |
> |
* Poll stale refs and remove them. Call only while holding lock. |
568 |
|
*/ |
569 |
< |
private boolean tryQuietlyInvoke() { |
570 |
< |
try { |
571 |
< |
if (!exec()) |
572 |
< |
return false; |
573 |
< |
} catch (Throwable rex) { |
574 |
< |
setDoneExceptionally(rex); |
575 |
< |
return false; |
569 |
> |
private static void expungeStaleExceptions() { |
570 |
> |
for (Object x; (x = exceptionTableRefQueue.poll()) != null;) { |
571 |
> |
if (x instanceof ExceptionNode) { |
572 |
> |
ForkJoinTask<?> key = ((ExceptionNode)x).get(); |
573 |
> |
ExceptionNode[] t = exceptionTable; |
574 |
> |
int i = System.identityHashCode(key) & (t.length - 1); |
575 |
> |
ExceptionNode e = t[i]; |
576 |
> |
ExceptionNode pred = null; |
577 |
> |
while (e != null) { |
578 |
> |
ExceptionNode next = e.next; |
579 |
> |
if (e == x) { |
580 |
> |
if (pred == null) |
581 |
> |
t[i] = next; |
582 |
> |
else |
583 |
> |
pred.next = next; |
584 |
> |
break; |
585 |
> |
} |
586 |
> |
pred = e; |
587 |
> |
e = next; |
588 |
> |
} |
589 |
> |
} |
590 |
|
} |
445 |
– |
setNormalCompletion(); |
446 |
– |
return true; |
591 |
|
} |
592 |
|
|
593 |
|
/** |
594 |
< |
* Cancel, ignoring any exceptions it throws |
594 |
> |
* If lock is available, poll stale refs and remove them. |
595 |
> |
* Called from ForkJoinPool when pools become quiescent. |
596 |
|
*/ |
597 |
< |
final void cancelIgnoringExceptions() { |
598 |
< |
try { |
599 |
< |
cancel(false); |
600 |
< |
} catch(Throwable ignore) { |
597 |
> |
static final void helpExpungeStaleExceptions() { |
598 |
> |
final ReentrantLock lock = exceptionTableLock; |
599 |
> |
if (lock.tryLock()) { |
600 |
> |
try { |
601 |
> |
expungeStaleExceptions(); |
602 |
> |
} finally { |
603 |
> |
lock.unlock(); |
604 |
> |
} |
605 |
|
} |
606 |
|
} |
607 |
|
|
608 |
|
/** |
609 |
< |
* Main implementation of helpJoin |
609 |
> |
* Throws exception, if any, associated with the given status. |
610 |
|
*/ |
611 |
< |
private int busyJoin(ForkJoinWorkerThread w) { |
612 |
< |
int s; |
613 |
< |
ForkJoinTask<?> t; |
614 |
< |
while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null) |
615 |
< |
t.quietlyExec(); |
616 |
< |
return (s >= 0)? awaitDone(w, false) : s; // block if no work |
611 |
> |
private void reportException(int s) { |
612 |
> |
Throwable ex = ((s == CANCELLED) ? new CancellationException() : |
613 |
> |
(s == EXCEPTIONAL) ? getThrowableException() : |
614 |
> |
null); |
615 |
> |
if (ex != null) |
616 |
> |
U.throwException(ex); |
617 |
|
} |
618 |
|
|
619 |
|
// public methods |
621 |
|
/** |
622 |
|
* Arranges to asynchronously execute this task. While it is not |
623 |
|
* necessarily enforced, it is a usage error to fork a task more |
624 |
< |
* than once unless it has completed and been reinitialized. This |
625 |
< |
* method may be invoked only from within ForkJoinTask |
626 |
< |
* computations. Attempts to invoke in other contexts result in |
627 |
< |
* exceptions or errors possibly including ClassCastException. |
624 |
> |
* than once unless it has completed and been reinitialized. |
625 |
> |
* Subsequent modifications to the state of this task or any data |
626 |
> |
* it operates on are not necessarily consistently observable by |
627 |
> |
* any thread other than the one executing it unless preceded by a |
628 |
> |
* call to {@link #join} or related methods, or a call to {@link |
629 |
> |
* #isDone} returning {@code true}. |
630 |
> |
* |
631 |
> |
* <p>This method may be invoked only from within {@code |
632 |
> |
* ForkJoinPool} computations (as may be determined using method |
633 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
634 |
> |
* result in exceptions or errors, possibly including {@code |
635 |
> |
* ClassCastException}. |
636 |
> |
* |
637 |
> |
* @return {@code this}, to simplify usage |
638 |
|
*/ |
639 |
< |
public final void fork() { |
640 |
< |
((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this); |
639 |
> |
public final ForkJoinTask<V> fork() { |
640 |
> |
((ForkJoinWorkerThread)Thread.currentThread()).workQueue.push(this); |
641 |
> |
return this; |
642 |
|
} |
643 |
|
|
644 |
|
/** |
645 |
< |
* Returns the result of the computation when it is ready. |
646 |
< |
* This method differs from <code>get</code> in that abnormal |
647 |
< |
* completion results in RuntimeExceptions or Errors, not |
648 |
< |
* ExecutionExceptions. |
645 |
> |
* Returns the result of the computation when it {@link #isDone is |
646 |
> |
* done}. This method differs from {@link #get()} in that |
647 |
> |
* abnormal completion results in {@code RuntimeException} or |
648 |
> |
* {@code Error}, not {@code ExecutionException}, and that |
649 |
> |
* interrupts of the calling thread do <em>not</em> cause the |
650 |
> |
* method to abruptly return by throwing {@code |
651 |
> |
* InterruptedException}. |
652 |
|
* |
653 |
|
* @return the computed result |
654 |
|
*/ |
655 |
|
public final V join() { |
656 |
< |
ForkJoinWorkerThread w = getWorker(); |
657 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryExec()) |
658 |
< |
reportException(awaitDone(w, true)); |
656 |
> |
int s; |
657 |
> |
if ((s = doJoin() & DONE_MASK) != NORMAL) |
658 |
> |
reportException(s); |
659 |
|
return getRawResult(); |
660 |
|
} |
661 |
|
|
662 |
|
/** |
663 |
|
* Commences performing this task, awaits its completion if |
664 |
< |
* necessary, and return its result. |
665 |
< |
* @throws Throwable (a RuntimeException, Error, or unchecked |
666 |
< |
* exception) if the underlying computation did so. |
664 |
> |
* necessary, and returns its result, or throws an (unchecked) |
665 |
> |
* {@code RuntimeException} or {@code Error} if the underlying |
666 |
> |
* computation did so. |
667 |
> |
* |
668 |
|
* @return the computed result |
669 |
|
*/ |
670 |
|
public final V invoke() { |
671 |
< |
if (status >= 0 && tryExec()) |
672 |
< |
return getRawResult(); |
673 |
< |
else |
674 |
< |
return join(); |
671 |
> |
int s; |
672 |
> |
if ((s = doInvoke() & DONE_MASK) != NORMAL) |
673 |
> |
reportException(s); |
674 |
> |
return getRawResult(); |
675 |
|
} |
676 |
|
|
677 |
|
/** |
678 |
< |
* Forks both tasks, returning when <code>isDone</code> holds for |
679 |
< |
* both of them or an exception is encountered. This method may be |
680 |
< |
* invoked only from within ForkJoinTask computations. Attempts to |
681 |
< |
* invoke in other contexts result in exceptions or errors |
682 |
< |
* possibly including ClassCastException. |
683 |
< |
* @param t1 one task |
684 |
< |
* @param t2 the other task |
685 |
< |
* @throws NullPointerException if t1 or t2 are null |
686 |
< |
* @throws RuntimeException or Error if either task did so. |
678 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
679 |
> |
* each task or an (unchecked) exception is encountered, in which |
680 |
> |
* case the exception is rethrown. If more than one task |
681 |
> |
* encounters an exception, then this method throws any one of |
682 |
> |
* these exceptions. If any task encounters an exception, the |
683 |
> |
* other may be cancelled. However, the execution status of |
684 |
> |
* individual tasks is not guaranteed upon exceptional return. The |
685 |
> |
* status of each task may be obtained using {@link |
686 |
> |
* #getException()} and related methods to check if they have been |
687 |
> |
* cancelled, completed normally or exceptionally, or left |
688 |
> |
* unprocessed. |
689 |
> |
* |
690 |
> |
* <p>This method may be invoked only from within {@code |
691 |
> |
* ForkJoinPool} computations (as may be determined using method |
692 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
693 |
> |
* result in exceptions or errors, possibly including {@code |
694 |
> |
* ClassCastException}. |
695 |
> |
* |
696 |
> |
* @param t1 the first task |
697 |
> |
* @param t2 the second task |
698 |
> |
* @throws NullPointerException if any task is null |
699 |
|
*/ |
700 |
< |
public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) { |
700 |
> |
public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) { |
701 |
> |
int s1, s2; |
702 |
|
t2.fork(); |
703 |
< |
t1.invoke(); |
704 |
< |
t2.join(); |
703 |
> |
if ((s1 = t1.doInvoke() & DONE_MASK) != NORMAL) |
704 |
> |
t1.reportException(s1); |
705 |
> |
if ((s2 = t2.doJoin() & DONE_MASK) != NORMAL) |
706 |
> |
t2.reportException(s2); |
707 |
|
} |
708 |
|
|
709 |
|
/** |
710 |
< |
* Forks the given tasks, returning when <code>isDone</code> holds |
711 |
< |
* for all of them. If any task encounters an exception, others |
712 |
< |
* may be cancelled. This method may be invoked only from within |
713 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
714 |
< |
* result in exceptions or errors possibly including ClassCastException. |
715 |
< |
* @param tasks the array of tasks |
716 |
< |
* @throws NullPointerException if tasks or any element are null. |
717 |
< |
* @throws RuntimeException or Error if any task did so. |
710 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
711 |
> |
* each task or an (unchecked) exception is encountered, in which |
712 |
> |
* case the exception is rethrown. If more than one task |
713 |
> |
* encounters an exception, then this method throws any one of |
714 |
> |
* these exceptions. If any task encounters an exception, others |
715 |
> |
* may be cancelled. However, the execution status of individual |
716 |
> |
* tasks is not guaranteed upon exceptional return. The status of |
717 |
> |
* each task may be obtained using {@link #getException()} and |
718 |
> |
* related methods to check if they have been cancelled, completed |
719 |
> |
* normally or exceptionally, or left unprocessed. |
720 |
> |
* |
721 |
> |
* <p>This method may be invoked only from within {@code |
722 |
> |
* ForkJoinPool} computations (as may be determined using method |
723 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
724 |
> |
* result in exceptions or errors, possibly including {@code |
725 |
> |
* ClassCastException}. |
726 |
> |
* |
727 |
> |
* @param tasks the tasks |
728 |
> |
* @throws NullPointerException if any task is null |
729 |
|
*/ |
730 |
|
public static void invokeAll(ForkJoinTask<?>... tasks) { |
731 |
|
Throwable ex = null; |
738 |
|
} |
739 |
|
else if (i != 0) |
740 |
|
t.fork(); |
741 |
< |
else { |
742 |
< |
t.quietlyInvoke(); |
553 |
< |
if (ex == null) |
554 |
< |
ex = t.getException(); |
555 |
< |
} |
741 |
> |
else if (t.doInvoke() < NORMAL && ex == null) |
742 |
> |
ex = t.getException(); |
743 |
|
} |
744 |
|
for (int i = 1; i <= last; ++i) { |
745 |
|
ForkJoinTask<?> t = tasks[i]; |
746 |
|
if (t != null) { |
747 |
|
if (ex != null) |
748 |
|
t.cancel(false); |
749 |
< |
else { |
750 |
< |
t.quietlyJoin(); |
564 |
< |
if (ex == null) |
565 |
< |
ex = t.getException(); |
566 |
< |
} |
749 |
> |
else if (t.doJoin() < NORMAL) |
750 |
> |
ex = t.getException(); |
751 |
|
} |
752 |
|
} |
753 |
|
if (ex != null) |
754 |
< |
rethrowException(ex); |
754 |
> |
U.throwException(ex); |
755 |
|
} |
756 |
|
|
757 |
|
/** |
758 |
< |
* Forks all tasks in the collection, returning when |
759 |
< |
* <code>isDone</code> holds for all of them. If any task |
760 |
< |
* encounters an exception, others may be cancelled. This method |
761 |
< |
* may be invoked only from within ForkJoinTask |
762 |
< |
* computations. Attempts to invoke in other contexts resul!t in |
763 |
< |
* exceptions or errors possibly including ClassCastException. |
758 |
> |
* Forks all tasks in the specified collection, returning when |
759 |
> |
* {@code isDone} holds for each task or an (unchecked) exception |
760 |
> |
* is encountered, in which case the exception is rethrown. If |
761 |
> |
* more than one task encounters an exception, then this method |
762 |
> |
* throws any one of these exceptions. If any task encounters an |
763 |
> |
* exception, others may be cancelled. However, the execution |
764 |
> |
* status of individual tasks is not guaranteed upon exceptional |
765 |
> |
* return. The status of each task may be obtained using {@link |
766 |
> |
* #getException()} and related methods to check if they have been |
767 |
> |
* cancelled, completed normally or exceptionally, or left |
768 |
> |
* unprocessed. |
769 |
> |
* |
770 |
> |
* <p>This method may be invoked only from within {@code |
771 |
> |
* ForkJoinPool} computations (as may be determined using method |
772 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
773 |
> |
* result in exceptions or errors, possibly including {@code |
774 |
> |
* ClassCastException}. |
775 |
> |
* |
776 |
|
* @param tasks the collection of tasks |
777 |
< |
* @throws NullPointerException if tasks or any element are null. |
778 |
< |
* @throws RuntimeException or Error if any task did so. |
777 |
> |
* @return the tasks argument, to simplify usage |
778 |
> |
* @throws NullPointerException if tasks or any element are null |
779 |
|
*/ |
780 |
< |
public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) { |
781 |
< |
if (!(tasks instanceof List)) { |
782 |
< |
invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()])); |
783 |
< |
return; |
780 |
> |
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
781 |
> |
if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) { |
782 |
> |
invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()])); |
783 |
> |
return tasks; |
784 |
|
} |
785 |
+ |
@SuppressWarnings("unchecked") |
786 |
|
List<? extends ForkJoinTask<?>> ts = |
787 |
< |
(List<? extends ForkJoinTask<?>>)tasks; |
787 |
> |
(List<? extends ForkJoinTask<?>>) tasks; |
788 |
|
Throwable ex = null; |
789 |
|
int last = ts.size() - 1; |
790 |
|
for (int i = last; i >= 0; --i) { |
795 |
|
} |
796 |
|
else if (i != 0) |
797 |
|
t.fork(); |
798 |
< |
else { |
799 |
< |
t.quietlyInvoke(); |
603 |
< |
if (ex == null) |
604 |
< |
ex = t.getException(); |
605 |
< |
} |
798 |
> |
else if (t.doInvoke() < NORMAL && ex == null) |
799 |
> |
ex = t.getException(); |
800 |
|
} |
801 |
|
for (int i = 1; i <= last; ++i) { |
802 |
|
ForkJoinTask<?> t = ts.get(i); |
803 |
|
if (t != null) { |
804 |
|
if (ex != null) |
805 |
|
t.cancel(false); |
806 |
< |
else { |
807 |
< |
t.quietlyJoin(); |
614 |
< |
if (ex == null) |
615 |
< |
ex = t.getException(); |
616 |
< |
} |
806 |
> |
else if (t.doJoin() < NORMAL) |
807 |
> |
ex = t.getException(); |
808 |
|
} |
809 |
|
} |
810 |
|
if (ex != null) |
811 |
< |
rethrowException(ex); |
811 |
> |
U.throwException(ex); |
812 |
> |
return tasks; |
813 |
|
} |
814 |
|
|
815 |
|
/** |
816 |
< |
* Returns true if the computation performed by this task has |
817 |
< |
* completed (or has been cancelled). |
818 |
< |
* @return true if this computation has completed |
816 |
> |
* Attempts to cancel execution of this task. This attempt will |
817 |
> |
* fail if the task has already completed or could not be |
818 |
> |
* cancelled for some other reason. If successful, and this task |
819 |
> |
* has not started when {@code cancel} is called, execution of |
820 |
> |
* this task is suppressed. After this method returns |
821 |
> |
* successfully, unless there is an intervening call to {@link |
822 |
> |
* #reinitialize}, subsequent calls to {@link #isCancelled}, |
823 |
> |
* {@link #isDone}, and {@code cancel} will return {@code true} |
824 |
> |
* and calls to {@link #join} and related methods will result in |
825 |
> |
* {@code CancellationException}. |
826 |
> |
* |
827 |
> |
* <p>This method may be overridden in subclasses, but if so, must |
828 |
> |
* still ensure that these properties hold. In particular, the |
829 |
> |
* {@code cancel} method itself must not throw exceptions. |
830 |
> |
* |
831 |
> |
* <p>This method is designed to be invoked by <em>other</em> |
832 |
> |
* tasks. To terminate the current task, you can just return or |
833 |
> |
* throw an unchecked exception from its computation method, or |
834 |
> |
* invoke {@link #completeExceptionally}. |
835 |
> |
* |
836 |
> |
* @param mayInterruptIfRunning this value has no effect in the |
837 |
> |
* default implementation because interrupts are not used to |
838 |
> |
* control cancellation. |
839 |
> |
* |
840 |
> |
* @return {@code true} if this task is now cancelled |
841 |
|
*/ |
842 |
+ |
public boolean cancel(boolean mayInterruptIfRunning) { |
843 |
+ |
return (setCompletion(CANCELLED) & DONE_MASK) == CANCELLED; |
844 |
+ |
} |
845 |
+ |
|
846 |
|
public final boolean isDone() { |
847 |
|
return status < 0; |
848 |
|
} |
849 |
|
|
632 |
– |
/** |
633 |
– |
* Returns true if this task was cancelled. |
634 |
– |
* @return true if this task was cancelled |
635 |
– |
*/ |
850 |
|
public final boolean isCancelled() { |
851 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
851 |
> |
return (status & DONE_MASK) == CANCELLED; |
852 |
|
} |
853 |
|
|
854 |
|
/** |
855 |
< |
* Asserts that the results of this task's computation will not be |
642 |
< |
* used. If a cancellation occurs before atempting to execute this |
643 |
< |
* task, then execution will be suppressed, <code>isCancelled</code> |
644 |
< |
* will report true, and <code>join</code> will result in a |
645 |
< |
* <code>CancellationException</code> being thrown. Otherwise, when |
646 |
< |
* cancellation races with completion, there are no guarantees |
647 |
< |
* about whether <code>isCancelled</code> will report true, whether |
648 |
< |
* <code>join</code> will return normally or via an exception, or |
649 |
< |
* whether these behaviors will remain consistent upon repeated |
650 |
< |
* invocation. |
651 |
< |
* |
652 |
< |
* <p>This method may be overridden in subclasses, but if so, must |
653 |
< |
* still ensure that these minimal properties hold. In particular, |
654 |
< |
* the cancel method itself must not throw exceptions. |
655 |
< |
* |
656 |
< |
* <p> This method is designed to be invoked by <em>other</em> |
657 |
< |
* tasks. To terminate the current task, you can just return or |
658 |
< |
* throw an unchecked exception from its computation method, or |
659 |
< |
* invoke <code>completeExceptionally</code>. |
660 |
< |
* |
661 |
< |
* @param mayInterruptIfRunning this value is ignored in the |
662 |
< |
* default implementation because tasks are not in general |
663 |
< |
* cancelled via interruption. |
855 |
> |
* Returns {@code true} if this task threw an exception or was cancelled. |
856 |
|
* |
857 |
< |
* @return true if this task is now cancelled |
857 |
> |
* @return {@code true} if this task threw an exception or was cancelled |
858 |
|
*/ |
859 |
< |
public boolean cancel(boolean mayInterruptIfRunning) { |
860 |
< |
setCompletion(CANCELLED); |
669 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
859 |
> |
public final boolean isCompletedAbnormally() { |
860 |
> |
return status < NORMAL; |
861 |
|
} |
862 |
|
|
863 |
|
/** |
864 |
< |
* Returns true if this task threw an exception or was cancelled |
865 |
< |
* @return true if this task threw an exception or was cancelled |
864 |
> |
* Returns {@code true} if this task completed without throwing an |
865 |
> |
* exception and was not cancelled. |
866 |
> |
* |
867 |
> |
* @return {@code true} if this task completed without throwing an |
868 |
> |
* exception and was not cancelled |
869 |
|
*/ |
870 |
< |
public final boolean isCompletedAbnormally() { |
871 |
< |
return (status & COMPLETION_MASK) < NORMAL; |
870 |
> |
public final boolean isCompletedNormally() { |
871 |
> |
return (status & DONE_MASK) == NORMAL; |
872 |
|
} |
873 |
|
|
874 |
|
/** |
875 |
|
* Returns the exception thrown by the base computation, or a |
876 |
< |
* CancellationException if cancelled, or null if none or if the |
877 |
< |
* method has not yet completed. |
878 |
< |
* @return the exception, or null if none |
876 |
> |
* {@code CancellationException} if cancelled, or {@code null} if |
877 |
> |
* none or if the method has not yet completed. |
878 |
> |
* |
879 |
> |
* @return the exception, or {@code null} if none |
880 |
|
*/ |
881 |
|
public final Throwable getException() { |
882 |
< |
int s = status & COMPLETION_MASK; |
883 |
< |
if (s >= NORMAL) |
884 |
< |
return null; |
885 |
< |
if (s == CANCELLED) |
691 |
< |
return new CancellationException(); |
692 |
< |
return exceptionMap.get(this); |
882 |
> |
int s = status & DONE_MASK; |
883 |
> |
return ((s >= NORMAL) ? null : |
884 |
> |
(s == CANCELLED) ? new CancellationException() : |
885 |
> |
getThrowableException()); |
886 |
|
} |
887 |
|
|
888 |
|
/** |
889 |
|
* Completes this task abnormally, and if not already aborted or |
890 |
|
* cancelled, causes it to throw the given exception upon |
891 |
< |
* <code>join</code> and related operations. This method may be used |
891 |
> |
* {@code join} and related operations. This method may be used |
892 |
|
* to induce exceptions in asynchronous tasks, or to force |
893 |
|
* completion of tasks that would not otherwise complete. Its use |
894 |
< |
* in other situations is likely to be wrong. This method is |
895 |
< |
* overridable, but overridden versions must invoke <code>super</code> |
894 |
> |
* in other situations is discouraged. This method is |
895 |
> |
* overridable, but overridden versions must invoke {@code super} |
896 |
|
* implementation to maintain guarantees. |
897 |
|
* |
898 |
< |
* @param ex the exception to throw. If this exception is |
899 |
< |
* not a RuntimeException or Error, the actual exception thrown |
900 |
< |
* will be a RuntimeException with cause ex. |
898 |
> |
* @param ex the exception to throw. If this exception is not a |
899 |
> |
* {@code RuntimeException} or {@code Error}, the actual exception |
900 |
> |
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
901 |
|
*/ |
902 |
|
public void completeExceptionally(Throwable ex) { |
903 |
< |
setDoneExceptionally((ex instanceof RuntimeException) || |
904 |
< |
(ex instanceof Error)? ex : |
905 |
< |
new RuntimeException(ex)); |
903 |
> |
setExceptionalCompletion((ex instanceof RuntimeException) || |
904 |
> |
(ex instanceof Error) ? ex : |
905 |
> |
new RuntimeException(ex)); |
906 |
|
} |
907 |
|
|
908 |
|
/** |
909 |
|
* Completes this task, and if not already aborted or cancelled, |
910 |
< |
* returning a <code>null</code> result upon <code>join</code> and related |
911 |
< |
* operations. This method may be used to provide results for |
912 |
< |
* asynchronous tasks, or to provide alternative handling for |
913 |
< |
* tasks that would not otherwise complete normally. Its use in |
914 |
< |
* other situations is likely to be wrong. This method is |
915 |
< |
* overridable, but overridden versions must invoke <code>super</code> |
916 |
< |
* implementation to maintain guarantees. |
910 |
> |
* returning the given value as the result of subsequent |
911 |
> |
* invocations of {@code join} and related operations. This method |
912 |
> |
* may be used to provide results for asynchronous tasks, or to |
913 |
> |
* provide alternative handling for tasks that would not otherwise |
914 |
> |
* complete normally. Its use in other situations is |
915 |
> |
* discouraged. This method is overridable, but overridden |
916 |
> |
* versions must invoke {@code super} implementation to maintain |
917 |
> |
* guarantees. |
918 |
|
* |
919 |
< |
* @param value the result value for this task. |
919 |
> |
* @param value the result value for this task |
920 |
|
*/ |
921 |
|
public void complete(V value) { |
922 |
|
try { |
923 |
|
setRawResult(value); |
924 |
< |
} catch(Throwable rex) { |
925 |
< |
setDoneExceptionally(rex); |
924 |
> |
} catch (Throwable rex) { |
925 |
> |
setExceptionalCompletion(rex); |
926 |
|
return; |
927 |
|
} |
928 |
< |
setNormalCompletion(); |
735 |
< |
} |
736 |
< |
|
737 |
< |
public final V get() throws InterruptedException, ExecutionException { |
738 |
< |
ForkJoinWorkerThread w = getWorker(); |
739 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
740 |
< |
awaitDone(w, true); |
741 |
< |
return reportFutureResult(); |
928 |
> |
setCompletion(NORMAL); |
929 |
|
} |
930 |
|
|
931 |
< |
public final V get(long timeout, TimeUnit unit) |
932 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
933 |
< |
ForkJoinWorkerThread w = getWorker(); |
934 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
935 |
< |
awaitDone(w, unit.toNanos(timeout)); |
936 |
< |
return reportTimedFutureResult(); |
931 |
> |
/** |
932 |
> |
* Completes this task normally without setting a value. The most |
933 |
> |
* recent value established by {@link #setRawResult} (or {@code |
934 |
> |
* null} by default) will be returned as the result of subsequent |
935 |
> |
* invocations of {@code join} and related operations. |
936 |
> |
* |
937 |
> |
* @since 1.8 |
938 |
> |
*/ |
939 |
> |
public final void quietlyComplete() { |
940 |
> |
setCompletion(NORMAL); |
941 |
|
} |
942 |
|
|
943 |
|
/** |
944 |
< |
* Possibly executes other tasks until this task is ready, then |
945 |
< |
* returns the result of the computation. This method may be more |
946 |
< |
* efficient than <code>join</code>, but is only applicable when |
756 |
< |
* there are no potemtial dependencies between continuation of the |
757 |
< |
* current task and that of any other task that might be executed |
758 |
< |
* while helping. (This usually holds for pure divide-and-conquer |
759 |
< |
* tasks). This method may be invoked only from within |
760 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
761 |
< |
* resul!t in exceptions or errors possibly including ClassCastException. |
944 |
> |
* Waits if necessary for the computation to complete, and then |
945 |
> |
* retrieves its result. |
946 |
> |
* |
947 |
|
* @return the computed result |
948 |
+ |
* @throws CancellationException if the computation was cancelled |
949 |
+ |
* @throws ExecutionException if the computation threw an |
950 |
+ |
* exception |
951 |
+ |
* @throws InterruptedException if the current thread is not a |
952 |
+ |
* member of a ForkJoinPool and was interrupted while waiting |
953 |
|
*/ |
954 |
< |
public final V helpJoin() { |
955 |
< |
ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread()); |
956 |
< |
if (status < 0 || !w.unpushTask(this) || !tryExec()) |
957 |
< |
reportException(busyJoin(w)); |
954 |
> |
public final V get() throws InterruptedException, ExecutionException { |
955 |
> |
int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ? |
956 |
> |
doJoin() : externalInterruptibleAwaitDone(); |
957 |
> |
Throwable ex; |
958 |
> |
if ((s &= DONE_MASK) == CANCELLED) |
959 |
> |
throw new CancellationException(); |
960 |
> |
if (s == EXCEPTIONAL && (ex = getThrowableException()) != null) |
961 |
> |
throw new ExecutionException(ex); |
962 |
|
return getRawResult(); |
963 |
|
} |
964 |
|
|
965 |
|
/** |
966 |
< |
* Possibly executes other tasks until this task is ready. This |
967 |
< |
* method may be invoked only from within ForkJoinTask |
968 |
< |
* computations. Attempts to invoke in other contexts resul!t in |
969 |
< |
* exceptions or errors possibly including ClassCastException. |
966 |
> |
* Waits if necessary for at most the given time for the computation |
967 |
> |
* to complete, and then retrieves its result, if available. |
968 |
> |
* |
969 |
> |
* @param timeout the maximum time to wait |
970 |
> |
* @param unit the time unit of the timeout argument |
971 |
> |
* @return the computed result |
972 |
> |
* @throws CancellationException if the computation was cancelled |
973 |
> |
* @throws ExecutionException if the computation threw an |
974 |
> |
* exception |
975 |
> |
* @throws InterruptedException if the current thread is not a |
976 |
> |
* member of a ForkJoinPool and was interrupted while waiting |
977 |
> |
* @throws TimeoutException if the wait timed out |
978 |
|
*/ |
979 |
< |
public final void quietlyHelpJoin() { |
980 |
< |
if (status >= 0) { |
981 |
< |
ForkJoinWorkerThread w = |
982 |
< |
(ForkJoinWorkerThread)(Thread.currentThread()); |
983 |
< |
if (!w.unpushTask(this) || !tryQuietlyInvoke()) |
984 |
< |
busyJoin(w); |
979 |
> |
public final V get(long timeout, TimeUnit unit) |
980 |
> |
throws InterruptedException, ExecutionException, TimeoutException { |
981 |
> |
if (Thread.interrupted()) |
982 |
> |
throw new InterruptedException(); |
983 |
> |
// Messy in part because we measure in nanosecs, but wait in millisecs |
984 |
> |
int s; long ns, ms; |
985 |
> |
if ((s = status) >= 0 && (ns = unit.toNanos(timeout)) > 0L) { |
986 |
> |
long deadline = System.nanoTime() + ns; |
987 |
> |
ForkJoinPool p = null; |
988 |
> |
ForkJoinPool.WorkQueue w = null; |
989 |
> |
Thread t = Thread.currentThread(); |
990 |
> |
if (t instanceof ForkJoinWorkerThread) { |
991 |
> |
ForkJoinWorkerThread wt = (ForkJoinWorkerThread)t; |
992 |
> |
p = wt.pool; |
993 |
> |
w = wt.workQueue; |
994 |
> |
s = p.helpJoinOnce(w, this); // no retries on failure |
995 |
> |
} |
996 |
> |
boolean canBlock = false; |
997 |
> |
boolean interrupted = false; |
998 |
> |
try { |
999 |
> |
while ((s = status) >= 0) { |
1000 |
> |
if (w != null && w.runState < 0) |
1001 |
> |
cancelIgnoringExceptions(this); |
1002 |
> |
else if (!canBlock) { |
1003 |
> |
if (p == null || p.tryCompensate(this, null)) |
1004 |
> |
canBlock = true; |
1005 |
> |
} |
1006 |
> |
else { |
1007 |
> |
if ((ms = TimeUnit.NANOSECONDS.toMillis(ns)) > 0L && |
1008 |
> |
U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) { |
1009 |
> |
synchronized (this) { |
1010 |
> |
if (status >= 0) { |
1011 |
> |
try { |
1012 |
> |
wait(ms); |
1013 |
> |
} catch (InterruptedException ie) { |
1014 |
> |
if (p == null) |
1015 |
> |
interrupted = true; |
1016 |
> |
} |
1017 |
> |
} |
1018 |
> |
else |
1019 |
> |
notifyAll(); |
1020 |
> |
} |
1021 |
> |
} |
1022 |
> |
if ((s = status) < 0 || interrupted || |
1023 |
> |
(ns = deadline - System.nanoTime()) <= 0L) |
1024 |
> |
break; |
1025 |
> |
} |
1026 |
> |
} |
1027 |
> |
} finally { |
1028 |
> |
if (p != null && canBlock) |
1029 |
> |
p.incrementActiveCount(); |
1030 |
> |
} |
1031 |
> |
if (interrupted) |
1032 |
> |
throw new InterruptedException(); |
1033 |
> |
} |
1034 |
> |
if ((s &= DONE_MASK) != NORMAL) { |
1035 |
> |
Throwable ex; |
1036 |
> |
if (s == CANCELLED) |
1037 |
> |
throw new CancellationException(); |
1038 |
> |
if (s != EXCEPTIONAL) |
1039 |
> |
throw new TimeoutException(); |
1040 |
> |
if ((ex = getThrowableException()) != null) |
1041 |
> |
throw new ExecutionException(ex); |
1042 |
|
} |
1043 |
+ |
return getRawResult(); |
1044 |
|
} |
1045 |
|
|
1046 |
|
/** |
1047 |
< |
* Joins this task, without returning its result or throwing an |
1047 |
> |
* Joins this task, without returning its result or throwing its |
1048 |
|
* exception. This method may be useful when processing |
1049 |
|
* collections of tasks when some have been cancelled or otherwise |
1050 |
|
* known to have aborted. |
1051 |
|
*/ |
1052 |
|
public final void quietlyJoin() { |
1053 |
< |
if (status >= 0) { |
794 |
< |
ForkJoinWorkerThread w = getWorker(); |
795 |
< |
if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke()) |
796 |
< |
awaitDone(w, true); |
797 |
< |
} |
1053 |
> |
doJoin(); |
1054 |
|
} |
1055 |
|
|
1056 |
|
/** |
1057 |
|
* Commences performing this task and awaits its completion if |
1058 |
< |
* necessary, without returning its result or throwing an |
1059 |
< |
* exception. This method may be useful when processing |
804 |
< |
* collections of tasks when some have been cancelled or otherwise |
805 |
< |
* known to have aborted. |
1058 |
> |
* necessary, without returning its result or throwing its |
1059 |
> |
* exception. |
1060 |
|
*/ |
1061 |
|
public final void quietlyInvoke() { |
1062 |
< |
if (status >= 0 && !tryQuietlyInvoke()) |
809 |
< |
quietlyJoin(); |
1062 |
> |
doInvoke(); |
1063 |
|
} |
1064 |
|
|
1065 |
|
/** |
1066 |
|
* Possibly executes tasks until the pool hosting the current task |
1067 |
< |
* {@link ForkJoinPool#isQuiescent}. This method may be of use in |
1068 |
< |
* designs in which many tasks are forked, but none are explicitly |
1069 |
< |
* joined, instead executing them until all are processed. |
1067 |
> |
* {@link ForkJoinPool#isQuiescent is quiescent}. This method may |
1068 |
> |
* be of use in designs in which many tasks are forked, but none |
1069 |
> |
* are explicitly joined, instead executing them until all are |
1070 |
> |
* processed. |
1071 |
> |
* |
1072 |
> |
* <p>This method may be invoked only from within {@code |
1073 |
> |
* ForkJoinPool} computations (as may be determined using method |
1074 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1075 |
> |
* result in exceptions or errors, possibly including {@code |
1076 |
> |
* ClassCastException}. |
1077 |
|
*/ |
1078 |
|
public static void helpQuiesce() { |
1079 |
< |
((ForkJoinWorkerThread)(Thread.currentThread())). |
1080 |
< |
helpQuiescePool(); |
1079 |
> |
ForkJoinWorkerThread wt = |
1080 |
> |
(ForkJoinWorkerThread)Thread.currentThread(); |
1081 |
> |
wt.pool.helpQuiescePool(wt.workQueue); |
1082 |
|
} |
1083 |
|
|
1084 |
|
/** |
1085 |
|
* Resets the internal bookkeeping state of this task, allowing a |
1086 |
< |
* subsequent <code>fork</code>. This method allows repeated reuse of |
1086 |
> |
* subsequent {@code fork}. This method allows repeated reuse of |
1087 |
|
* this task, but only if reuse occurs when this task has either |
1088 |
|
* never been forked, or has been forked, then completed and all |
1089 |
|
* outstanding joins of this task have also completed. Effects |
1090 |
< |
* under any other usage conditions are not guaranteed, and are |
1091 |
< |
* almost surely wrong. This method may be useful when executing |
1090 |
> |
* under any other usage conditions are not guaranteed. |
1091 |
> |
* This method may be useful when executing |
1092 |
|
* pre-constructed trees of subtasks in loops. |
1093 |
+ |
* |
1094 |
+ |
* <p>Upon completion of this method, {@code isDone()} reports |
1095 |
+ |
* {@code false}, and {@code getException()} reports {@code |
1096 |
+ |
* null}. However, the value returned by {@code getRawResult} is |
1097 |
+ |
* unaffected. To clear this value, you can invoke {@code |
1098 |
+ |
* setRawResult(null)}. |
1099 |
|
*/ |
1100 |
|
public void reinitialize() { |
1101 |
< |
if ((status & COMPLETION_MASK) == EXCEPTIONAL) |
1102 |
< |
exceptionMap.remove(this); |
1103 |
< |
status = 0; |
1101 |
> |
if ((status & DONE_MASK) == EXCEPTIONAL) |
1102 |
> |
clearExceptionalCompletion(); |
1103 |
> |
else |
1104 |
> |
status = 0; |
1105 |
|
} |
1106 |
|
|
1107 |
|
/** |
1108 |
|
* Returns the pool hosting the current task execution, or null |
1109 |
< |
* if this task is executing outside of any pool. |
1110 |
< |
* @return the pool, or null if none. |
1109 |
> |
* if this task is executing outside of any ForkJoinPool. |
1110 |
> |
* |
1111 |
> |
* @see #inForkJoinPool |
1112 |
> |
* @return the pool, or {@code null} if none |
1113 |
|
*/ |
1114 |
|
public static ForkJoinPool getPool() { |
1115 |
|
Thread t = Thread.currentThread(); |
1116 |
< |
return ((t instanceof ForkJoinWorkerThread)? |
1117 |
< |
((ForkJoinWorkerThread)t).pool : null); |
1116 |
> |
return (t instanceof ForkJoinWorkerThread) ? |
1117 |
> |
((ForkJoinWorkerThread) t).pool : null; |
1118 |
> |
} |
1119 |
> |
|
1120 |
> |
/** |
1121 |
> |
* Returns {@code true} if the current thread is a {@link |
1122 |
> |
* ForkJoinWorkerThread} executing as a ForkJoinPool computation. |
1123 |
> |
* |
1124 |
> |
* @return {@code true} if the current thread is a {@link |
1125 |
> |
* ForkJoinWorkerThread} executing as a ForkJoinPool computation, |
1126 |
> |
* or {@code false} otherwise |
1127 |
> |
*/ |
1128 |
> |
public static boolean inForkJoinPool() { |
1129 |
> |
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
1130 |
|
} |
1131 |
|
|
1132 |
|
/** |
1135 |
|
* by the current thread, and has not commenced executing in |
1136 |
|
* another thread. This method may be useful when arranging |
1137 |
|
* alternative local processing of tasks that could have been, but |
1138 |
< |
* were not, stolen. This method may be invoked only from within |
1139 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
1140 |
< |
* result in exceptions or errors possibly including ClassCastException. |
1141 |
< |
* @return true if unforked |
1138 |
> |
* were not, stolen. |
1139 |
> |
* |
1140 |
> |
* <p>This method may be invoked only from within {@code |
1141 |
> |
* ForkJoinPool} computations (as may be determined using method |
1142 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1143 |
> |
* result in exceptions or errors, possibly including {@code |
1144 |
> |
* ClassCastException}. |
1145 |
> |
* |
1146 |
> |
* @return {@code true} if unforked |
1147 |
|
*/ |
1148 |
|
public boolean tryUnfork() { |
1149 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this); |
1149 |
> |
return ((ForkJoinWorkerThread)Thread.currentThread()) |
1150 |
> |
.workQueue.tryUnpush(this); |
1151 |
|
} |
1152 |
|
|
1153 |
|
/** |
1155 |
|
* forked by the current worker thread but not yet executed. This |
1156 |
|
* value may be useful for heuristic decisions about whether to |
1157 |
|
* fork other tasks. |
1158 |
+ |
* |
1159 |
+ |
* <p>This method may be invoked only from within {@code |
1160 |
+ |
* ForkJoinPool} computations (as may be determined using method |
1161 |
+ |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1162 |
+ |
* result in exceptions or errors, possibly including {@code |
1163 |
+ |
* ClassCastException}. |
1164 |
+ |
* |
1165 |
|
* @return the number of tasks |
1166 |
|
*/ |
1167 |
|
public static int getQueuedTaskCount() { |
1168 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
1169 |
< |
getQueueSize(); |
1168 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1169 |
> |
.workQueue.queueSize(); |
1170 |
|
} |
1171 |
|
|
1172 |
|
/** |
1173 |
< |
* Returns a estimate of how many more locally queued tasks are |
1173 |
> |
* Returns an estimate of how many more locally queued tasks are |
1174 |
|
* held by the current worker thread than there are other worker |
1175 |
|
* threads that might steal them. This value may be useful for |
1176 |
|
* heuristic decisions about whether to fork other tasks. In many |
1178 |
|
* aim to maintain a small constant surplus (for example, 3) of |
1179 |
|
* tasks, and to process computations locally if this threshold is |
1180 |
|
* exceeded. |
1181 |
+ |
* |
1182 |
+ |
* <p>This method may be invoked only from within {@code |
1183 |
+ |
* ForkJoinPool} computations (as may be determined using method |
1184 |
+ |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1185 |
+ |
* result in exceptions or errors, possibly including {@code |
1186 |
+ |
* ClassCastException}. |
1187 |
+ |
* |
1188 |
|
* @return the surplus number of tasks, which may be negative |
1189 |
|
*/ |
1190 |
|
public static int getSurplusQueuedTaskCount() { |
1191 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())) |
1192 |
< |
.getEstimatedSurplusTaskCount(); |
1191 |
> |
/* |
1192 |
> |
* The aim of this method is to return a cheap heuristic guide |
1193 |
> |
* for task partitioning when programmers, frameworks, tools, |
1194 |
> |
* or languages have little or no idea about task granularity. |
1195 |
> |
* In essence by offering this method, we ask users only about |
1196 |
> |
* tradeoffs in overhead vs expected throughput and its |
1197 |
> |
* variance, rather than how finely to partition tasks. |
1198 |
> |
* |
1199 |
> |
* In a steady state strict (tree-structured) computation, |
1200 |
> |
* each thread makes available for stealing enough tasks for |
1201 |
> |
* other threads to remain active. Inductively, if all threads |
1202 |
> |
* play by the same rules, each thread should make available |
1203 |
> |
* only a constant number of tasks. |
1204 |
> |
* |
1205 |
> |
* The minimum useful constant is just 1. But using a value of |
1206 |
> |
* 1 would require immediate replenishment upon each steal to |
1207 |
> |
* maintain enough tasks, which is infeasible. Further, |
1208 |
> |
* partitionings/granularities of offered tasks should |
1209 |
> |
* minimize steal rates, which in general means that threads |
1210 |
> |
* nearer the top of computation tree should generate more |
1211 |
> |
* than those nearer the bottom. In perfect steady state, each |
1212 |
> |
* thread is at approximately the same level of computation |
1213 |
> |
* tree. However, producing extra tasks amortizes the |
1214 |
> |
* uncertainty of progress and diffusion assumptions. |
1215 |
> |
* |
1216 |
> |
* So, users will want to use values larger, but not much |
1217 |
> |
* larger than 1 to both smooth over transient shortages and |
1218 |
> |
* hedge against uneven progress; as traded off against the |
1219 |
> |
* cost of extra task overhead. We leave the user to pick a |
1220 |
> |
* threshold value to compare with the results of this call to |
1221 |
> |
* guide decisions, but recommend values such as 3. |
1222 |
> |
* |
1223 |
> |
* When all threads are active, it is on average OK to |
1224 |
> |
* estimate surplus strictly locally. In steady-state, if one |
1225 |
> |
* thread is maintaining say 2 surplus tasks, then so are |
1226 |
> |
* others. So we can just use estimated queue length. |
1227 |
> |
* However, this strategy alone leads to serious mis-estimates |
1228 |
> |
* in some non-steady-state conditions (ramp-up, ramp-down, |
1229 |
> |
* other stalls). We can detect many of these by further |
1230 |
> |
* considering the number of "idle" threads, that are known to |
1231 |
> |
* have zero queued tasks, so compensate by a factor of |
1232 |
> |
* (#idle/#active) threads. |
1233 |
> |
*/ |
1234 |
> |
ForkJoinWorkerThread wt = |
1235 |
> |
(ForkJoinWorkerThread)Thread.currentThread(); |
1236 |
> |
return wt.workQueue.queueSize() - wt.pool.idlePerActive(); |
1237 |
|
} |
1238 |
|
|
1239 |
|
// Extension methods |
1240 |
|
|
1241 |
|
/** |
1242 |
< |
* Returns the result that would be returned by <code>join</code>, |
1243 |
< |
* even if this task completed abnormally, or null if this task is |
1244 |
< |
* not known to have been completed. This method is designed to |
1245 |
< |
* aid debugging, as well as to support extensions. Its use in any |
1246 |
< |
* other context is discouraged. |
1242 |
> |
* Returns the result that would be returned by {@link #join}, even |
1243 |
> |
* if this task completed abnormally, or {@code null} if this task |
1244 |
> |
* is not known to have been completed. This method is designed |
1245 |
> |
* to aid debugging, as well as to support extensions. Its use in |
1246 |
> |
* any other context is discouraged. |
1247 |
|
* |
1248 |
< |
* @return the result, or null if not completed. |
1248 |
> |
* @return the result, or {@code null} if not completed |
1249 |
|
*/ |
1250 |
|
public abstract V getRawResult(); |
1251 |
|
|
1259 |
|
protected abstract void setRawResult(V value); |
1260 |
|
|
1261 |
|
/** |
1262 |
< |
* Immediately performs the base action of this task. This method |
1263 |
< |
* is designed to support extensions, and should not in general be |
1264 |
< |
* called otherwise. The return value controls whether this task |
1265 |
< |
* is considered to be done normally. It may return false in |
1262 |
> |
* Immediately performs the base action of this task and returns |
1263 |
> |
* true if, upon return from this method, this task is guaranteed |
1264 |
> |
* to have completed normally. This method may return false |
1265 |
> |
* otherwise, to indicate that this task is not necessarily |
1266 |
> |
* complete (or is not known to be complete), for example in |
1267 |
|
* asynchronous actions that require explicit invocations of |
1268 |
< |
* <code>complete</code> to become joinable. It may throw exceptions |
1269 |
< |
* to indicate abnormal exit. |
1270 |
< |
* @return true if completed normally |
1271 |
< |
* @throws Error or RuntimeException if encountered during computation |
1268 |
> |
* completion methods. This method may also throw an (unchecked) |
1269 |
> |
* exception to indicate abnormal exit. This method is designed to |
1270 |
> |
* support extensions, and should not in general be called |
1271 |
> |
* otherwise. |
1272 |
> |
* |
1273 |
> |
* @return {@code true} if this task is known to have completed normally |
1274 |
|
*/ |
1275 |
|
protected abstract boolean exec(); |
1276 |
|
|
1277 |
|
/** |
1278 |
< |
* Returns, but does not unschedule or execute, the task queued by |
1279 |
< |
* the current thread but not yet executed, if one is |
1278 |
> |
* Returns, but does not unschedule or execute, a task queued by |
1279 |
> |
* the current thread but not yet executed, if one is immediately |
1280 |
|
* available. There is no guarantee that this task will actually |
1281 |
< |
* be polled or executed next. This method is designed primarily |
1282 |
< |
* to support extensions, and is unlikely to be useful otherwise. |
1283 |
< |
* This method may be invoked only from within ForkJoinTask |
1284 |
< |
* computations. Attempts to invoke in other contexts result in |
1285 |
< |
* exceptions or errors possibly including ClassCastException. |
1281 |
> |
* be polled or executed next. Conversely, this method may return |
1282 |
> |
* null even if a task exists but cannot be accessed without |
1283 |
> |
* contention with other threads. This method is designed |
1284 |
> |
* primarily to support extensions, and is unlikely to be useful |
1285 |
> |
* otherwise. |
1286 |
> |
* |
1287 |
> |
* <p>This method may be invoked only from within {@code |
1288 |
> |
* ForkJoinPool} computations (as may be determined using method |
1289 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1290 |
> |
* result in exceptions or errors, possibly including {@code |
1291 |
> |
* ClassCastException}. |
1292 |
|
* |
1293 |
< |
* @return the next task, or null if none are available |
1293 |
> |
* @return the next task, or {@code null} if none are available |
1294 |
|
*/ |
1295 |
|
protected static ForkJoinTask<?> peekNextLocalTask() { |
1296 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).peekTask(); |
1296 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()).workQueue.peek(); |
1297 |
|
} |
1298 |
|
|
1299 |
|
/** |
1300 |
|
* Unschedules and returns, without executing, the next task |
1301 |
|
* queued by the current thread but not yet executed. This method |
1302 |
|
* is designed primarily to support extensions, and is unlikely to |
1303 |
< |
* be useful otherwise. This method may be invoked only from |
1304 |
< |
* within ForkJoinTask computations. Attempts to invoke in other |
1305 |
< |
* contexts result in exceptions or errors possibly including |
1306 |
< |
* ClassCastException. |
1303 |
> |
* be useful otherwise. |
1304 |
> |
* |
1305 |
> |
* <p>This method may be invoked only from within {@code |
1306 |
> |
* ForkJoinPool} computations (as may be determined using method |
1307 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1308 |
> |
* result in exceptions or errors, possibly including {@code |
1309 |
> |
* ClassCastException}. |
1310 |
|
* |
1311 |
< |
* @return the next task, or null if none are available |
1311 |
> |
* @return the next task, or {@code null} if none are available |
1312 |
|
*/ |
1313 |
|
protected static ForkJoinTask<?> pollNextLocalTask() { |
1314 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).pollLocalTask(); |
1314 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1315 |
> |
.workQueue.nextLocalTask(); |
1316 |
|
} |
1317 |
|
|
1318 |
|
/** |
1320 |
|
* queued by the current thread but not yet executed, if one is |
1321 |
|
* available, or if not available, a task that was forked by some |
1322 |
|
* other thread, if available. Availability may be transient, so a |
1323 |
< |
* <code>null</code> result does not necessarily imply quiecence |
1323 |
> |
* {@code null} result does not necessarily imply quiescence |
1324 |
|
* of the pool this task is operating in. This method is designed |
1325 |
|
* primarily to support extensions, and is unlikely to be useful |
1326 |
< |
* otherwise. This method may be invoked only from within |
968 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
969 |
< |
* result in exceptions or errors possibly including |
970 |
< |
* ClassCastException. |
1326 |
> |
* otherwise. |
1327 |
|
* |
1328 |
< |
* @return a task, or null if none are available |
1328 |
> |
* <p>This method may be invoked only from within {@code |
1329 |
> |
* ForkJoinPool} computations (as may be determined using method |
1330 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1331 |
> |
* result in exceptions or errors, possibly including {@code |
1332 |
> |
* ClassCastException}. |
1333 |
> |
* |
1334 |
> |
* @return a task, or {@code null} if none are available |
1335 |
|
*/ |
1336 |
|
protected static ForkJoinTask<?> pollTask() { |
1337 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
1338 |
< |
pollTask(); |
1337 |
> |
ForkJoinWorkerThread wt = |
1338 |
> |
(ForkJoinWorkerThread)Thread.currentThread(); |
1339 |
> |
return wt.pool.nextTaskFor(wt.workQueue); |
1340 |
> |
} |
1341 |
> |
|
1342 |
> |
// tag operations |
1343 |
> |
|
1344 |
> |
/** |
1345 |
> |
* Returns the tag for this task. |
1346 |
> |
* |
1347 |
> |
* @return the tag for this task |
1348 |
> |
* @since 1.8 |
1349 |
> |
*/ |
1350 |
> |
public final short getForkJoinTaskTag() { |
1351 |
> |
return (short)status; |
1352 |
> |
} |
1353 |
> |
|
1354 |
> |
/** |
1355 |
> |
* Atomically sets the tag value for this task. |
1356 |
> |
* |
1357 |
> |
* @param tag the tag value |
1358 |
> |
* @return the previous value of the tag |
1359 |
> |
* @since 1.8 |
1360 |
> |
*/ |
1361 |
> |
public final short setForkJoinTaskTag(short tag) { |
1362 |
> |
for (int s;;) { |
1363 |
> |
if (U.compareAndSwapInt(this, STATUS, s = status, |
1364 |
> |
(s & ~SMASK) | (tag & SMASK))) |
1365 |
> |
return (short)s; |
1366 |
> |
} |
1367 |
> |
} |
1368 |
> |
|
1369 |
> |
/** |
1370 |
> |
* Atomically conditionally sets the tag value for this task. |
1371 |
> |
* Among other applications, tags can be used as visit markers |
1372 |
> |
* in tasks operating on graphs, as in methods that check: {@code |
1373 |
> |
* if (task.compareAndSetForkJoinTaskTag((short)0, (short)1))} |
1374 |
> |
* before processing, otherwise exiting because the node has |
1375 |
> |
* already been visited. |
1376 |
> |
* |
1377 |
> |
* @param e the expected tag value |
1378 |
> |
* @param tag the new tag value |
1379 |
> |
* @return true if successful; i.e., the current value was |
1380 |
> |
* equal to e and is now tag. |
1381 |
> |
* @since 1.8 |
1382 |
> |
*/ |
1383 |
> |
public final boolean compareAndSetForkJoinTaskTag(short e, short tag) { |
1384 |
> |
for (int s;;) { |
1385 |
> |
if ((short)(s = status) != e) |
1386 |
> |
return false; |
1387 |
> |
if (U.compareAndSwapInt(this, STATUS, s, |
1388 |
> |
(s & ~SMASK) | (tag & SMASK))) |
1389 |
> |
return true; |
1390 |
> |
} |
1391 |
> |
} |
1392 |
> |
|
1393 |
> |
/** |
1394 |
> |
* Adaptor for Runnables. This implements RunnableFuture |
1395 |
> |
* to be compliant with AbstractExecutorService constraints |
1396 |
> |
* when used in ForkJoinPool. |
1397 |
> |
*/ |
1398 |
> |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
1399 |
> |
implements RunnableFuture<T> { |
1400 |
> |
final Runnable runnable; |
1401 |
> |
T result; |
1402 |
> |
AdaptedRunnable(Runnable runnable, T result) { |
1403 |
> |
if (runnable == null) throw new NullPointerException(); |
1404 |
> |
this.runnable = runnable; |
1405 |
> |
this.result = result; // OK to set this even before completion |
1406 |
> |
} |
1407 |
> |
public final T getRawResult() { return result; } |
1408 |
> |
public final void setRawResult(T v) { result = v; } |
1409 |
> |
public final boolean exec() { runnable.run(); return true; } |
1410 |
> |
public final void run() { invoke(); } |
1411 |
> |
private static final long serialVersionUID = 5232453952276885070L; |
1412 |
> |
} |
1413 |
> |
|
1414 |
> |
/** |
1415 |
> |
* Adaptor for Runnables without results |
1416 |
> |
*/ |
1417 |
> |
static final class AdaptedRunnableAction extends ForkJoinTask<Void> |
1418 |
> |
implements RunnableFuture<Void> { |
1419 |
> |
final Runnable runnable; |
1420 |
> |
AdaptedRunnableAction(Runnable runnable) { |
1421 |
> |
if (runnable == null) throw new NullPointerException(); |
1422 |
> |
this.runnable = runnable; |
1423 |
> |
} |
1424 |
> |
public final Void getRawResult() { return null; } |
1425 |
> |
public final void setRawResult(Void v) { } |
1426 |
> |
public final boolean exec() { runnable.run(); return true; } |
1427 |
> |
public final void run() { invoke(); } |
1428 |
> |
private static final long serialVersionUID = 5232453952276885070L; |
1429 |
> |
} |
1430 |
> |
|
1431 |
> |
/** |
1432 |
> |
* Adaptor for Callables |
1433 |
> |
*/ |
1434 |
> |
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
1435 |
> |
implements RunnableFuture<T> { |
1436 |
> |
final Callable<? extends T> callable; |
1437 |
> |
T result; |
1438 |
> |
AdaptedCallable(Callable<? extends T> callable) { |
1439 |
> |
if (callable == null) throw new NullPointerException(); |
1440 |
> |
this.callable = callable; |
1441 |
> |
} |
1442 |
> |
public final T getRawResult() { return result; } |
1443 |
> |
public final void setRawResult(T v) { result = v; } |
1444 |
> |
public final boolean exec() { |
1445 |
> |
try { |
1446 |
> |
result = callable.call(); |
1447 |
> |
return true; |
1448 |
> |
} catch (Error err) { |
1449 |
> |
throw err; |
1450 |
> |
} catch (RuntimeException rex) { |
1451 |
> |
throw rex; |
1452 |
> |
} catch (Exception ex) { |
1453 |
> |
throw new RuntimeException(ex); |
1454 |
> |
} |
1455 |
> |
} |
1456 |
> |
public final void run() { invoke(); } |
1457 |
> |
private static final long serialVersionUID = 2838392045355241008L; |
1458 |
> |
} |
1459 |
> |
|
1460 |
> |
/** |
1461 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1462 |
> |
* method of the given {@code Runnable} as its action, and returns |
1463 |
> |
* a null result upon {@link #join}. |
1464 |
> |
* |
1465 |
> |
* @param runnable the runnable action |
1466 |
> |
* @return the task |
1467 |
> |
*/ |
1468 |
> |
public static ForkJoinTask<?> adapt(Runnable runnable) { |
1469 |
> |
return new AdaptedRunnableAction(runnable); |
1470 |
> |
} |
1471 |
> |
|
1472 |
> |
/** |
1473 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1474 |
> |
* method of the given {@code Runnable} as its action, and returns |
1475 |
> |
* the given result upon {@link #join}. |
1476 |
> |
* |
1477 |
> |
* @param runnable the runnable action |
1478 |
> |
* @param result the result upon completion |
1479 |
> |
* @return the task |
1480 |
> |
*/ |
1481 |
> |
public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) { |
1482 |
> |
return new AdaptedRunnable<T>(runnable, result); |
1483 |
> |
} |
1484 |
> |
|
1485 |
> |
/** |
1486 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code call} |
1487 |
> |
* method of the given {@code Callable} as its action, and returns |
1488 |
> |
* its result upon {@link #join}, translating any checked exceptions |
1489 |
> |
* encountered into {@code RuntimeException}. |
1490 |
> |
* |
1491 |
> |
* @param callable the callable action |
1492 |
> |
* @return the task |
1493 |
> |
*/ |
1494 |
> |
public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) { |
1495 |
> |
return new AdaptedCallable<T>(callable); |
1496 |
|
} |
1497 |
|
|
1498 |
|
// Serialization support |
1500 |
|
private static final long serialVersionUID = -7721805057305804111L; |
1501 |
|
|
1502 |
|
/** |
1503 |
< |
* Save the state to a stream. |
1503 |
> |
* Saves this task to a stream (that is, serializes it). |
1504 |
|
* |
1505 |
|
* @serialData the current run status and the exception thrown |
1506 |
< |
* during execution, or null if none. |
988 |
< |
* @param s the stream |
1506 |
> |
* during execution, or {@code null} if none |
1507 |
|
*/ |
1508 |
|
private void writeObject(java.io.ObjectOutputStream s) |
1509 |
|
throws java.io.IOException { |
1512 |
|
} |
1513 |
|
|
1514 |
|
/** |
1515 |
< |
* Reconstitute the instance from a stream. |
998 |
< |
* @param s the stream |
1515 |
> |
* Reconstitutes this task from a stream (that is, deserializes it). |
1516 |
|
*/ |
1517 |
|
private void readObject(java.io.ObjectInputStream s) |
1518 |
|
throws java.io.IOException, ClassNotFoundException { |
1519 |
|
s.defaultReadObject(); |
1003 |
– |
status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts |
1004 |
– |
status |= EXTERNAL_SIGNAL; // conservatively set external signal |
1520 |
|
Object ex = s.readObject(); |
1521 |
|
if (ex != null) |
1522 |
< |
setDoneExceptionally((Throwable)ex); |
1522 |
> |
setExceptionalCompletion((Throwable)ex); |
1523 |
|
} |
1524 |
|
|
1525 |
< |
// Temporary Unsafe mechanics for preliminary release |
1526 |
< |
private static Unsafe getUnsafe() throws Throwable { |
1525 |
> |
// Unsafe mechanics |
1526 |
> |
private static final sun.misc.Unsafe U; |
1527 |
> |
private static final long STATUS; |
1528 |
> |
static { |
1529 |
> |
exceptionTableLock = new ReentrantLock(); |
1530 |
> |
exceptionTableRefQueue = new ReferenceQueue<Object>(); |
1531 |
> |
exceptionTable = new ExceptionNode[EXCEPTION_MAP_CAPACITY]; |
1532 |
> |
try { |
1533 |
> |
U = getUnsafe(); |
1534 |
> |
STATUS = U.objectFieldOffset |
1535 |
> |
(ForkJoinTask.class.getDeclaredField("status")); |
1536 |
> |
} catch (Exception e) { |
1537 |
> |
throw new Error(e); |
1538 |
> |
} |
1539 |
> |
} |
1540 |
> |
|
1541 |
> |
/** |
1542 |
> |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1543 |
> |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1544 |
> |
* into a jdk. |
1545 |
> |
* |
1546 |
> |
* @return a sun.misc.Unsafe |
1547 |
> |
*/ |
1548 |
> |
private static sun.misc.Unsafe getUnsafe() { |
1549 |
|
try { |
1550 |
< |
return Unsafe.getUnsafe(); |
1550 |
> |
return sun.misc.Unsafe.getUnsafe(); |
1551 |
|
} catch (SecurityException se) { |
1552 |
|
try { |
1553 |
|
return java.security.AccessController.doPrivileged |
1554 |
< |
(new java.security.PrivilegedExceptionAction<Unsafe>() { |
1555 |
< |
public Unsafe run() throws Exception { |
1556 |
< |
return getUnsafePrivileged(); |
1554 |
> |
(new java.security |
1555 |
> |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1556 |
> |
public sun.misc.Unsafe run() throws Exception { |
1557 |
> |
java.lang.reflect.Field f = sun.misc |
1558 |
> |
.Unsafe.class.getDeclaredField("theUnsafe"); |
1559 |
> |
f.setAccessible(true); |
1560 |
> |
return (sun.misc.Unsafe) f.get(null); |
1561 |
|
}}); |
1562 |
|
} catch (java.security.PrivilegedActionException e) { |
1563 |
< |
throw e.getCause(); |
1563 |
> |
throw new RuntimeException("Could not initialize intrinsics", |
1564 |
> |
e.getCause()); |
1565 |
|
} |
1566 |
|
} |
1567 |
|
} |
1026 |
– |
|
1027 |
– |
private static Unsafe getUnsafePrivileged() |
1028 |
– |
throws NoSuchFieldException, IllegalAccessException { |
1029 |
– |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
1030 |
– |
f.setAccessible(true); |
1031 |
– |
return (Unsafe) f.get(null); |
1032 |
– |
} |
1033 |
– |
|
1034 |
– |
private static long fieldOffset(String fieldName) |
1035 |
– |
throws NoSuchFieldException { |
1036 |
– |
return _unsafe.objectFieldOffset |
1037 |
– |
(ForkJoinTask.class.getDeclaredField(fieldName)); |
1038 |
– |
} |
1039 |
– |
|
1040 |
– |
static final Unsafe _unsafe; |
1041 |
– |
static final long statusOffset; |
1042 |
– |
|
1043 |
– |
static { |
1044 |
– |
try { |
1045 |
– |
_unsafe = getUnsafe(); |
1046 |
– |
statusOffset = fieldOffset("status"); |
1047 |
– |
} catch (Throwable e) { |
1048 |
– |
throw new RuntimeException("Could not initialize intrinsics", e); |
1049 |
– |
} |
1050 |
– |
} |
1051 |
– |
|
1568 |
|
} |