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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.util.concurrent.*; |
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import java.io.Serializable; |
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import java.util.Collection; |
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import java.util.Collections; |
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import java.util.List; |
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import java.util.Map; |
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import java.util.WeakHashMap; |
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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} |
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* and {@code join}, or derivatives such as |
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* {@code invokeAll}. 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 it is |
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* explicitly submitted to a {@link ForkJoinPool}, or, if not already |
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* engaged in a ForkJoin computation, commenced in the {@link |
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* ForkJoinPool#commonPool()} via {@link #fork}, {@link #invoke}, or |
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* related methods. Once started, it will usually in turn start other |
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* subtasks. As indicated by the name of this class, many programs |
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* using {@code ForkJoinTask} employ only methods {@link #fork} and |
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* {@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 support |
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* 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 I/O, 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} |
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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} |
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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 I/O. 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} |
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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()} 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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* 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} (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} |
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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} 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 (as may be determined using method {@link |
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* #inForkJoinPool}). Attempts to invoke them in other contexts |
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* result in exceptions or errors, possibly including |
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* 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. |
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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} 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} methods |
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* {@code exec}, {@code setRawResult}, and |
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* {@code getRawResult}, 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} 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, otherwise 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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* parallelism 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}, 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 directly 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 use 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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* 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 |
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* block performs a wait, notifyAll or both. |
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* |
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* These control bits occupy only (some of) the upper half (16 |
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* bits) of status field. The lower bits are used for user-defined |
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* tags. |
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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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/** The run status of this task */ |
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volatile int status; // accessed directly by pool and workers |
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static final int DONE_MASK = 0xf0000000; // mask out non-completion bits |
| 224 |
> |
static final int NORMAL = 0xf0000000; // must be negative |
| 225 |
> |
static final int CANCELLED = 0xc0000000; // must be < NORMAL |
| 226 |
> |
static final int EXCEPTIONAL = 0x80000000; // must be < CANCELLED |
| 227 |
> |
static final int SIGNAL = 0x00010000; // must be >= 1 << 16 |
| 228 |
> |
static final int SMASK = 0x0000ffff; // short bits for tags |
| 229 |
|
|
| 230 |
|
/** |
| 231 |
< |
* Gets current worker thread, or null if not a worker thread. |
| 231 |
> |
* Marks completion and wakes up threads waiting to join this |
| 232 |
> |
* task. |
| 233 |
> |
* |
| 234 |
> |
* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL |
| 235 |
> |
* @return completion status on exit |
| 236 |
|
*/ |
| 237 |
< |
static ForkJoinWorkerThread getWorker() { |
| 238 |
< |
Thread t = Thread.currentThread(); |
| 239 |
< |
return ((t instanceof ForkJoinWorkerThread) ? |
| 240 |
< |
(ForkJoinWorkerThread) t : null); |
| 237 |
> |
private int setCompletion(int completion) { |
| 238 |
> |
for (int s;;) { |
| 239 |
> |
if ((s = status) < 0) |
| 240 |
> |
return s; |
| 241 |
> |
if (U.compareAndSwapInt(this, STATUS, s, s | completion)) { |
| 242 |
> |
if ((s >>> 16) != 0) |
| 243 |
> |
synchronized (this) { notifyAll(); } |
| 244 |
> |
return completion; |
| 245 |
> |
} |
| 246 |
> |
} |
| 247 |
|
} |
| 248 |
|
|
| 249 |
< |
final boolean casStatus(int cmp, int val) { |
| 250 |
< |
return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val); |
| 249 |
> |
/** |
| 250 |
> |
* Primary execution method for stolen tasks. Unless done, calls |
| 251 |
> |
* exec and records status if completed, but doesn't wait for |
| 252 |
> |
* completion otherwise. |
| 253 |
> |
* |
| 254 |
> |
* @return status on exit from this method |
| 255 |
> |
*/ |
| 256 |
> |
final int doExec() { |
| 257 |
> |
int s; boolean completed; |
| 258 |
> |
if ((s = status) >= 0) { |
| 259 |
> |
try { |
| 260 |
> |
completed = exec(); |
| 261 |
> |
} catch (Throwable rex) { |
| 262 |
> |
return setExceptionalCompletion(rex); |
| 263 |
> |
} |
| 264 |
> |
if (completed) |
| 265 |
> |
s = setCompletion(NORMAL); |
| 266 |
> |
} |
| 267 |
> |
return s; |
| 268 |
|
} |
| 269 |
|
|
| 270 |
|
/** |
| 271 |
< |
* Workaround for not being able to rethrow unchecked exceptions. |
| 271 |
> |
* Tries to set SIGNAL status unless already completed. Used by |
| 272 |
> |
* ForkJoinPool. Other variants are directly incorporated into |
| 273 |
> |
* externalAwaitDone etc. |
| 274 |
> |
* |
| 275 |
> |
* @return true if successful |
| 276 |
|
*/ |
| 277 |
< |
static void rethrowException(Throwable ex) { |
| 278 |
< |
if (ex != null) |
| 279 |
< |
UNSAFE.throwException(ex); |
| 277 |
> |
final boolean trySetSignal() { |
| 278 |
> |
int s = status; |
| 279 |
> |
return s >= 0 && U.compareAndSwapInt(this, STATUS, s, s | SIGNAL); |
| 280 |
|
} |
| 281 |
|
|
| 184 |
– |
// Setting completion status |
| 185 |
– |
|
| 282 |
|
/** |
| 283 |
< |
* Marks completion and wakes up threads waiting to join this task. |
| 284 |
< |
* |
| 189 |
< |
* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL |
| 283 |
> |
* Blocks a non-worker-thread until completion. |
| 284 |
> |
* @return status upon completion |
| 285 |
|
*/ |
| 286 |
< |
final void setCompletion(int completion) { |
| 287 |
< |
ForkJoinPool pool = getPool(); |
| 288 |
< |
if (pool != null) { |
| 289 |
< |
int s; // Clear signal bits while setting completion status |
| 290 |
< |
do {} while ((s = status) >= 0 && !casStatus(s, completion)); |
| 291 |
< |
|
| 292 |
< |
if ((s & SIGNAL_MASK) != 0) { |
| 293 |
< |
if ((s &= INTERNAL_SIGNAL_MASK) != 0) |
| 294 |
< |
pool.updateRunningCount(s); |
| 295 |
< |
synchronized (this) { notifyAll(); } |
| 286 |
> |
private int externalAwaitDone() { |
| 287 |
> |
int s; |
| 288 |
> |
ForkJoinPool.externalHelpJoin(this); |
| 289 |
> |
boolean interrupted = false; |
| 290 |
> |
while ((s = status) >= 0) { |
| 291 |
> |
if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) { |
| 292 |
> |
synchronized (this) { |
| 293 |
> |
if (status >= 0) { |
| 294 |
> |
try { |
| 295 |
> |
wait(); |
| 296 |
> |
} catch (InterruptedException ie) { |
| 297 |
> |
interrupted = true; |
| 298 |
> |
} |
| 299 |
> |
} |
| 300 |
> |
else |
| 301 |
> |
notifyAll(); |
| 302 |
> |
} |
| 303 |
|
} |
| 304 |
|
} |
| 305 |
< |
else |
| 306 |
< |
externallySetCompletion(completion); |
| 305 |
> |
if (interrupted) |
| 306 |
> |
Thread.currentThread().interrupt(); |
| 307 |
> |
return s; |
| 308 |
|
} |
| 309 |
|
|
| 310 |
|
/** |
| 311 |
< |
* Version of setCompletion for non-FJ threads. Leaves signal |
| 209 |
< |
* bits for unblocked threads to adjust, and always notifies. |
| 311 |
> |
* Blocks a non-worker-thread until completion or interruption. |
| 312 |
|
*/ |
| 313 |
< |
private void externallySetCompletion(int completion) { |
| 313 |
> |
private int externalInterruptibleAwaitDone() throws InterruptedException { |
| 314 |
|
int s; |
| 315 |
< |
do {} while ((s = status) >= 0 && |
| 316 |
< |
!casStatus(s, (s & SIGNAL_MASK) | completion)); |
| 317 |
< |
synchronized (this) { notifyAll(); } |
| 315 |
> |
if (Thread.interrupted()) |
| 316 |
> |
throw new InterruptedException(); |
| 317 |
> |
ForkJoinPool.externalHelpJoin(this); |
| 318 |
> |
while ((s = status) >= 0) { |
| 319 |
> |
if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) { |
| 320 |
> |
synchronized (this) { |
| 321 |
> |
if (status >= 0) |
| 322 |
> |
wait(); |
| 323 |
> |
else |
| 324 |
> |
notifyAll(); |
| 325 |
> |
} |
| 326 |
> |
} |
| 327 |
> |
} |
| 328 |
> |
return s; |
| 329 |
|
} |
| 330 |
|
|
| 331 |
+ |
|
| 332 |
|
/** |
| 333 |
< |
* Sets status to indicate normal completion. |
| 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 |
< |
final void setNormalCompletion() { |
| 340 |
< |
// Try typical fast case -- single CAS, no signal, not already done. |
| 341 |
< |
// Manually expand casStatus to improve chances of inlining it |
| 342 |
< |
if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL)) |
| 343 |
< |
setCompletion(NORMAL); |
| 339 |
> |
private int doJoin() { |
| 340 |
> |
int s; Thread t; ForkJoinWorkerThread wt; ForkJoinPool.WorkQueue w; |
| 341 |
> |
return (s = status) < 0 ? s : |
| 342 |
> |
((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
| 343 |
> |
(w = (wt = (ForkJoinWorkerThread)t).workQueue). |
| 344 |
> |
tryUnpush(this) && (s = doExec()) < 0 ? s : |
| 345 |
> |
wt.pool.awaitJoin(w, this) : |
| 346 |
> |
externalAwaitDone(); |
| 347 |
|
} |
| 348 |
|
|
| 228 |
– |
// internal waiting and notification |
| 229 |
– |
|
| 349 |
|
/** |
| 350 |
< |
* Performs the actual monitor wait for awaitDone. |
| 350 |
> |
* Implementation for invoke, quietlyInvoke. |
| 351 |
> |
* |
| 352 |
> |
* @return status upon completion |
| 353 |
|
*/ |
| 354 |
< |
private void doAwaitDone() { |
| 355 |
< |
// Minimize lock bias and in/de-flation effects by maximizing |
| 356 |
< |
// chances of waiting inside sync |
| 357 |
< |
try { |
| 358 |
< |
while (status >= 0) |
| 359 |
< |
synchronized (this) { if (status >= 0) wait(); } |
| 239 |
< |
} catch (InterruptedException ie) { |
| 240 |
< |
onInterruptedWait(); |
| 241 |
< |
} |
| 354 |
> |
private int doInvoke() { |
| 355 |
> |
int s; Thread t; ForkJoinWorkerThread wt; |
| 356 |
> |
return (s = doExec()) < 0 ? s : |
| 357 |
> |
((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
| 358 |
> |
(wt = (ForkJoinWorkerThread)t).pool.awaitJoin(wt.workQueue, this) : |
| 359 |
> |
externalAwaitDone(); |
| 360 |
|
} |
| 361 |
|
|
| 362 |
+ |
// Exception table support |
| 363 |
+ |
|
| 364 |
|
/** |
| 365 |
< |
* Performs the actual timed monitor wait for awaitDone. |
| 365 |
> |
* Table of exceptions thrown by tasks, to enable reporting by |
| 366 |
> |
* callers. Because exceptions are rare, we don't directly keep |
| 367 |
> |
* them with task objects, but instead use a weak ref table. Note |
| 368 |
> |
* that cancellation exceptions don't appear in the table, but are |
| 369 |
> |
* instead recorded as status values. |
| 370 |
> |
* |
| 371 |
> |
* Note: These statics are initialized below in static block. |
| 372 |
|
*/ |
| 373 |
< |
private void doAwaitDone(long startTime, long nanos) { |
| 374 |
< |
synchronized (this) { |
| 375 |
< |
try { |
| 250 |
< |
while (status >= 0) { |
| 251 |
< |
long nt = nanos - System.nanoTime() - startTime; |
| 252 |
< |
if (nt <= 0) |
| 253 |
< |
break; |
| 254 |
< |
wait(nt / 1000000, (int) (nt % 1000000)); |
| 255 |
< |
} |
| 256 |
< |
} catch (InterruptedException ie) { |
| 257 |
< |
onInterruptedWait(); |
| 258 |
< |
} |
| 259 |
< |
} |
| 260 |
< |
} |
| 373 |
> |
private static final ExceptionNode[] exceptionTable; |
| 374 |
> |
private static final ReentrantLock exceptionTableLock; |
| 375 |
> |
private static final ReferenceQueue<Object> exceptionTableRefQueue; |
| 376 |
|
|
| 377 |
< |
// Awaiting completion |
| 377 |
> |
/** |
| 378 |
> |
* Fixed capacity for exceptionTable. |
| 379 |
> |
*/ |
| 380 |
> |
private static final int EXCEPTION_MAP_CAPACITY = 32; |
| 381 |
|
|
| 382 |
|
/** |
| 383 |
< |
* Sets status to indicate there is joiner, then waits for join, |
| 384 |
< |
* surrounded with pool notifications. |
| 385 |
< |
* |
| 386 |
< |
* @return status upon exit |
| 383 |
> |
* Key-value nodes for exception table. The chained hash table |
| 384 |
> |
* uses identity comparisons, full locking, and weak references |
| 385 |
> |
* for keys. The table has a fixed capacity because it only |
| 386 |
> |
* maintains task exceptions long enough for joiners to access |
| 387 |
> |
* them, so should never become very large for sustained |
| 388 |
> |
* periods. However, since we do not know when the last joiner |
| 389 |
> |
* completes, we must use weak references and expunge them. We do |
| 390 |
> |
* so on each operation (hence full locking). Also, some thread in |
| 391 |
> |
* any ForkJoinPool will call helpExpungeStaleExceptions when its |
| 392 |
> |
* pool becomes isQuiescent. |
| 393 |
|
*/ |
| 394 |
< |
private int awaitDone(ForkJoinWorkerThread w, |
| 395 |
< |
boolean maintainParallelism) { |
| 396 |
< |
ForkJoinPool pool = (w == null) ? null : w.pool; |
| 397 |
< |
int s; |
| 398 |
< |
while ((s = status) >= 0) { |
| 399 |
< |
if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) { |
| 400 |
< |
if (pool == null || !pool.preJoin(this, maintainParallelism)) |
| 401 |
< |
doAwaitDone(); |
| 402 |
< |
if (((s = status) & INTERNAL_SIGNAL_MASK) != 0) |
| 279 |
< |
adjustPoolCountsOnUnblock(pool); |
| 280 |
< |
break; |
| 281 |
< |
} |
| 394 |
> |
static final class ExceptionNode extends WeakReference<ForkJoinTask<?>> { |
| 395 |
> |
final Throwable ex; |
| 396 |
> |
ExceptionNode next; |
| 397 |
> |
final long thrower; // use id not ref to avoid weak cycles |
| 398 |
> |
ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) { |
| 399 |
> |
super(task, exceptionTableRefQueue); |
| 400 |
> |
this.ex = ex; |
| 401 |
> |
this.next = next; |
| 402 |
> |
this.thrower = Thread.currentThread().getId(); |
| 403 |
|
} |
| 283 |
– |
return s; |
| 404 |
|
} |
| 405 |
|
|
| 406 |
|
/** |
| 407 |
< |
* Timed version of awaitDone |
| 407 |
> |
* Records exception and sets status. |
| 408 |
|
* |
| 409 |
< |
* @return status upon exit |
| 409 |
> |
* @return status on exit |
| 410 |
|
*/ |
| 411 |
< |
private int awaitDone(ForkJoinWorkerThread w, long nanos) { |
| 292 |
< |
ForkJoinPool pool = (w == null) ? null : w.pool; |
| 411 |
> |
final int recordExceptionalCompletion(Throwable ex) { |
| 412 |
|
int s; |
| 413 |
< |
while ((s = status) >= 0) { |
| 414 |
< |
if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) { |
| 415 |
< |
long startTime = System.nanoTime(); |
| 416 |
< |
if (pool == null || !pool.preJoin(this, false)) |
| 417 |
< |
doAwaitDone(startTime, nanos); |
| 418 |
< |
if ((s = status) >= 0) { |
| 419 |
< |
adjustPoolCountsOnCancelledWait(pool); |
| 420 |
< |
s = status; |
| 413 |
> |
if ((s = status) >= 0) { |
| 414 |
> |
int h = System.identityHashCode(this); |
| 415 |
> |
final ReentrantLock lock = exceptionTableLock; |
| 416 |
> |
lock.lock(); |
| 417 |
> |
try { |
| 418 |
> |
expungeStaleExceptions(); |
| 419 |
> |
ExceptionNode[] t = exceptionTable; |
| 420 |
> |
int i = h & (t.length - 1); |
| 421 |
> |
for (ExceptionNode e = t[i]; ; e = e.next) { |
| 422 |
> |
if (e == null) { |
| 423 |
> |
t[i] = new ExceptionNode(this, ex, t[i]); |
| 424 |
> |
break; |
| 425 |
> |
} |
| 426 |
> |
if (e.get() == this) // already present |
| 427 |
> |
break; |
| 428 |
|
} |
| 429 |
< |
if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0) |
| 430 |
< |
adjustPoolCountsOnUnblock(pool); |
| 305 |
< |
break; |
| 429 |
> |
} finally { |
| 430 |
> |
lock.unlock(); |
| 431 |
|
} |
| 432 |
+ |
s = setCompletion(EXCEPTIONAL); |
| 433 |
|
} |
| 434 |
|
return s; |
| 435 |
|
} |
| 436 |
|
|
| 437 |
|
/** |
| 438 |
< |
* Notifies pool that thread is unblocked. Called by signalled |
| 439 |
< |
* threads when woken by non-FJ threads (which is atypical). |
| 438 |
> |
* Records exception and possibly propagates |
| 439 |
> |
* |
| 440 |
> |
* @return status on exit |
| 441 |
|
*/ |
| 442 |
< |
private void adjustPoolCountsOnUnblock(ForkJoinPool pool) { |
| 443 |
< |
int s; |
| 444 |
< |
do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK)); |
| 445 |
< |
if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0) |
| 446 |
< |
pool.updateRunningCount(s); |
| 442 |
> |
private int setExceptionalCompletion(Throwable ex) { |
| 443 |
> |
int s = recordExceptionalCompletion(ex); |
| 444 |
> |
if ((s & DONE_MASK) == EXCEPTIONAL) |
| 445 |
> |
internalPropagateException(ex); |
| 446 |
> |
return s; |
| 447 |
|
} |
| 448 |
|
|
| 449 |
|
/** |
| 450 |
< |
* Notifies pool to adjust counts on cancelled or timed out wait. |
| 450 |
> |
* Hook for exception propagation support for tasks with completers. |
| 451 |
|
*/ |
| 452 |
< |
private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) { |
| 326 |
< |
if (pool != null) { |
| 327 |
< |
int s; |
| 328 |
< |
while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) { |
| 329 |
< |
if (casStatus(s, s - 1)) { |
| 330 |
< |
pool.updateRunningCount(1); |
| 331 |
< |
break; |
| 332 |
< |
} |
| 333 |
< |
} |
| 334 |
< |
} |
| 452 |
> |
void internalPropagateException(Throwable ex) { |
| 453 |
|
} |
| 454 |
|
|
| 455 |
|
/** |
| 456 |
< |
* Handles interruptions during waits. |
| 456 |
> |
* Cancels, ignoring any exceptions thrown by cancel. Used during |
| 457 |
> |
* worker and pool shutdown. Cancel is spec'ed not to throw any |
| 458 |
> |
* exceptions, but if it does anyway, we have no recourse during |
| 459 |
> |
* shutdown, so guard against this case. |
| 460 |
|
*/ |
| 461 |
< |
private void onInterruptedWait() { |
| 462 |
< |
ForkJoinWorkerThread w = getWorker(); |
| 463 |
< |
if (w == null) |
| 464 |
< |
Thread.currentThread().interrupt(); // re-interrupt |
| 465 |
< |
else if (w.isTerminating()) |
| 466 |
< |
cancelIgnoringExceptions(); |
| 346 |
< |
// else if FJworker, ignore interrupt |
| 347 |
< |
} |
| 348 |
< |
|
| 349 |
< |
// Recording and reporting exceptions |
| 350 |
< |
|
| 351 |
< |
private void setDoneExceptionally(Throwable rex) { |
| 352 |
< |
exceptionMap.put(this, rex); |
| 353 |
< |
setCompletion(EXCEPTIONAL); |
| 354 |
< |
} |
| 355 |
< |
|
| 356 |
< |
/** |
| 357 |
< |
* Throws the exception associated with status s. |
| 358 |
< |
* |
| 359 |
< |
* @throws the exception |
| 360 |
< |
*/ |
| 361 |
< |
private void reportException(int s) { |
| 362 |
< |
if ((s &= COMPLETION_MASK) < NORMAL) { |
| 363 |
< |
if (s == CANCELLED) |
| 364 |
< |
throw new CancellationException(); |
| 365 |
< |
else |
| 366 |
< |
rethrowException(exceptionMap.get(this)); |
| 461 |
> |
static final void cancelIgnoringExceptions(ForkJoinTask<?> t) { |
| 462 |
> |
if (t != null && t.status >= 0) { |
| 463 |
> |
try { |
| 464 |
> |
t.cancel(false); |
| 465 |
> |
} catch (Throwable ignore) { |
| 466 |
> |
} |
| 467 |
|
} |
| 468 |
|
} |
| 469 |
|
|
| 470 |
|
/** |
| 471 |
< |
* Returns result or throws exception using j.u.c.Future conventions. |
| 372 |
< |
* Only call when {@code isDone} known to be true. |
| 471 |
> |
* Removes exception node and clears status |
| 472 |
|
*/ |
| 473 |
< |
private V reportFutureResult() |
| 474 |
< |
throws ExecutionException, InterruptedException { |
| 475 |
< |
int s = status & COMPLETION_MASK; |
| 476 |
< |
if (s < NORMAL) { |
| 477 |
< |
Throwable ex; |
| 478 |
< |
if (s == CANCELLED) |
| 479 |
< |
throw new CancellationException(); |
| 480 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
| 481 |
< |
throw new ExecutionException(ex); |
| 482 |
< |
if (Thread.interrupted()) |
| 483 |
< |
throw new InterruptedException(); |
| 473 |
> |
private void clearExceptionalCompletion() { |
| 474 |
> |
int h = System.identityHashCode(this); |
| 475 |
> |
final ReentrantLock lock = exceptionTableLock; |
| 476 |
> |
lock.lock(); |
| 477 |
> |
try { |
| 478 |
> |
ExceptionNode[] t = exceptionTable; |
| 479 |
> |
int i = h & (t.length - 1); |
| 480 |
> |
ExceptionNode e = t[i]; |
| 481 |
> |
ExceptionNode pred = null; |
| 482 |
> |
while (e != null) { |
| 483 |
> |
ExceptionNode next = e.next; |
| 484 |
> |
if (e.get() == this) { |
| 485 |
> |
if (pred == null) |
| 486 |
> |
t[i] = next; |
| 487 |
> |
else |
| 488 |
> |
pred.next = next; |
| 489 |
> |
break; |
| 490 |
> |
} |
| 491 |
> |
pred = e; |
| 492 |
> |
e = next; |
| 493 |
> |
} |
| 494 |
> |
expungeStaleExceptions(); |
| 495 |
> |
status = 0; |
| 496 |
> |
} finally { |
| 497 |
> |
lock.unlock(); |
| 498 |
|
} |
| 386 |
– |
return getRawResult(); |
| 499 |
|
} |
| 500 |
|
|
| 501 |
|
/** |
| 502 |
< |
* Returns result or throws exception using j.u.c.Future conventions |
| 503 |
< |
* with timeouts. |
| 502 |
> |
* Returns a rethrowable exception for the given task, if |
| 503 |
> |
* available. To provide accurate stack traces, if the exception |
| 504 |
> |
* was not thrown by the current thread, we try to create a new |
| 505 |
> |
* exception of the same type as the one thrown, but with the |
| 506 |
> |
* recorded exception as its cause. If there is no such |
| 507 |
> |
* constructor, we instead try to use a no-arg constructor, |
| 508 |
> |
* followed by initCause, to the same effect. If none of these |
| 509 |
> |
* apply, or any fail due to other exceptions, we return the |
| 510 |
> |
* recorded exception, which is still correct, although it may |
| 511 |
> |
* contain a misleading stack trace. |
| 512 |
> |
* |
| 513 |
> |
* @return the exception, or null if none |
| 514 |
|
*/ |
| 515 |
< |
private V reportTimedFutureResult() |
| 516 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
| 515 |
> |
private Throwable getThrowableException() { |
| 516 |
> |
if ((status & DONE_MASK) != EXCEPTIONAL) |
| 517 |
> |
return null; |
| 518 |
> |
int h = System.identityHashCode(this); |
| 519 |
> |
ExceptionNode e; |
| 520 |
> |
final ReentrantLock lock = exceptionTableLock; |
| 521 |
> |
lock.lock(); |
| 522 |
> |
try { |
| 523 |
> |
expungeStaleExceptions(); |
| 524 |
> |
ExceptionNode[] t = exceptionTable; |
| 525 |
> |
e = t[h & (t.length - 1)]; |
| 526 |
> |
while (e != null && e.get() != this) |
| 527 |
> |
e = e.next; |
| 528 |
> |
} finally { |
| 529 |
> |
lock.unlock(); |
| 530 |
> |
} |
| 531 |
|
Throwable ex; |
| 532 |
< |
int s = status & COMPLETION_MASK; |
| 533 |
< |
if (s == NORMAL) |
| 534 |
< |
return getRawResult(); |
| 535 |
< |
if (s == CANCELLED) |
| 536 |
< |
throw new CancellationException(); |
| 537 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
| 538 |
< |
throw new ExecutionException(ex); |
| 539 |
< |
if (Thread.interrupted()) |
| 540 |
< |
throw new InterruptedException(); |
| 541 |
< |
throw new TimeoutException(); |
| 532 |
> |
if (e == null || (ex = e.ex) == null) |
| 533 |
> |
return null; |
| 534 |
> |
if (false && e.thrower != Thread.currentThread().getId()) { |
| 535 |
> |
Class<? extends Throwable> ec = ex.getClass(); |
| 536 |
> |
try { |
| 537 |
> |
Constructor<?> noArgCtor = null; |
| 538 |
> |
Constructor<?>[] cs = ec.getConstructors();// public ctors only |
| 539 |
> |
for (int i = 0; i < cs.length; ++i) { |
| 540 |
> |
Constructor<?> c = cs[i]; |
| 541 |
> |
Class<?>[] ps = c.getParameterTypes(); |
| 542 |
> |
if (ps.length == 0) |
| 543 |
> |
noArgCtor = c; |
| 544 |
> |
else if (ps.length == 1 && ps[0] == Throwable.class) |
| 545 |
> |
return (Throwable)(c.newInstance(ex)); |
| 546 |
> |
} |
| 547 |
> |
if (noArgCtor != null) { |
| 548 |
> |
Throwable wx = (Throwable)(noArgCtor.newInstance()); |
| 549 |
> |
wx.initCause(ex); |
| 550 |
> |
return wx; |
| 551 |
> |
} |
| 552 |
> |
} catch (Exception ignore) { |
| 553 |
> |
} |
| 554 |
> |
} |
| 555 |
> |
return ex; |
| 556 |
|
} |
| 557 |
|
|
| 408 |
– |
// internal execution methods |
| 409 |
– |
|
| 558 |
|
/** |
| 559 |
< |
* Calls exec, recording completion, and rethrowing exception if |
| 412 |
< |
* encountered. Caller should normally check status before calling. |
| 413 |
< |
* |
| 414 |
< |
* @return true if completed normally |
| 559 |
> |
* Poll stale refs and remove them. Call only while holding lock. |
| 560 |
|
*/ |
| 561 |
< |
private boolean tryExec() { |
| 562 |
< |
try { // try block must contain only call to exec |
| 563 |
< |
if (!exec()) |
| 564 |
< |
return false; |
| 565 |
< |
} catch (Throwable rex) { |
| 566 |
< |
setDoneExceptionally(rex); |
| 567 |
< |
rethrowException(rex); |
| 568 |
< |
return false; // not reached |
| 561 |
> |
private static void expungeStaleExceptions() { |
| 562 |
> |
for (Object x; (x = exceptionTableRefQueue.poll()) != null;) { |
| 563 |
> |
if (x instanceof ExceptionNode) { |
| 564 |
> |
ForkJoinTask<?> key = ((ExceptionNode)x).get(); |
| 565 |
> |
ExceptionNode[] t = exceptionTable; |
| 566 |
> |
int i = System.identityHashCode(key) & (t.length - 1); |
| 567 |
> |
ExceptionNode e = t[i]; |
| 568 |
> |
ExceptionNode pred = null; |
| 569 |
> |
while (e != null) { |
| 570 |
> |
ExceptionNode next = e.next; |
| 571 |
> |
if (e == x) { |
| 572 |
> |
if (pred == null) |
| 573 |
> |
t[i] = next; |
| 574 |
> |
else |
| 575 |
> |
pred.next = next; |
| 576 |
> |
break; |
| 577 |
> |
} |
| 578 |
> |
pred = e; |
| 579 |
> |
e = next; |
| 580 |
> |
} |
| 581 |
> |
} |
| 582 |
|
} |
| 425 |
– |
setNormalCompletion(); |
| 426 |
– |
return true; |
| 583 |
|
} |
| 584 |
|
|
| 585 |
|
/** |
| 586 |
< |
* Main execution method used by worker threads. Invokes |
| 587 |
< |
* base computation unless already complete. |
| 586 |
> |
* If lock is available, poll stale refs and remove them. |
| 587 |
> |
* Called from ForkJoinPool when pools become quiescent. |
| 588 |
|
*/ |
| 589 |
< |
final void quietlyExec() { |
| 590 |
< |
if (status >= 0) { |
| 589 |
> |
static final void helpExpungeStaleExceptions() { |
| 590 |
> |
final ReentrantLock lock = exceptionTableLock; |
| 591 |
> |
if (lock.tryLock()) { |
| 592 |
|
try { |
| 593 |
< |
if (!exec()) |
| 594 |
< |
return; |
| 595 |
< |
} catch (Throwable rex) { |
| 439 |
< |
setDoneExceptionally(rex); |
| 440 |
< |
return; |
| 593 |
> |
expungeStaleExceptions(); |
| 594 |
> |
} finally { |
| 595 |
> |
lock.unlock(); |
| 596 |
|
} |
| 442 |
– |
setNormalCompletion(); |
| 597 |
|
} |
| 598 |
|
} |
| 599 |
|
|
| 600 |
|
/** |
| 601 |
< |
* Calls exec(), recording but not rethrowing exception. |
| 448 |
< |
* Caller should normally check status before calling. |
| 449 |
< |
* |
| 450 |
< |
* @return true if completed normally |
| 601 |
> |
* A version of "sneaky throw" to relay exceptions |
| 602 |
|
*/ |
| 603 |
< |
private boolean tryQuietlyInvoke() { |
| 604 |
< |
try { |
| 605 |
< |
if (!exec()) |
| 606 |
< |
return false; |
| 607 |
< |
} catch (Throwable rex) { |
| 608 |
< |
setDoneExceptionally(rex); |
| 609 |
< |
return false; |
| 603 |
> |
static void rethrow(final Throwable ex) { |
| 604 |
> |
if (ex != null) { |
| 605 |
> |
if (ex instanceof Error) |
| 606 |
> |
throw (Error)ex; |
| 607 |
> |
if (ex instanceof RuntimeException) |
| 608 |
> |
throw (RuntimeException)ex; |
| 609 |
> |
throw uncheckedThrowable(ex, RuntimeException.class); |
| 610 |
|
} |
| 460 |
– |
setNormalCompletion(); |
| 461 |
– |
return true; |
| 611 |
|
} |
| 612 |
|
|
| 613 |
|
/** |
| 614 |
< |
* Cancels, ignoring any exceptions it throws. |
| 614 |
> |
* The sneaky part of sneaky throw, relying on generics |
| 615 |
> |
* limitations to evade compiler complaints about rethrowing |
| 616 |
> |
* unchecked exceptions |
| 617 |
|
*/ |
| 618 |
< |
final void cancelIgnoringExceptions() { |
| 619 |
< |
try { |
| 620 |
< |
cancel(false); |
| 470 |
< |
} catch (Throwable ignore) { |
| 471 |
< |
} |
| 618 |
> |
@SuppressWarnings("unchecked") static <T extends Throwable> |
| 619 |
> |
T uncheckedThrowable(final Throwable t, final Class<T> c) { |
| 620 |
> |
return (T)t; // rely on vacuous cast |
| 621 |
|
} |
| 622 |
|
|
| 623 |
|
/** |
| 624 |
< |
* Main implementation of helpJoin |
| 624 |
> |
* Throws exception, if any, associated with the given status. |
| 625 |
|
*/ |
| 626 |
< |
private int busyJoin(ForkJoinWorkerThread w) { |
| 627 |
< |
int s; |
| 628 |
< |
ForkJoinTask<?> t; |
| 629 |
< |
while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null) |
| 630 |
< |
t.quietlyExec(); |
| 482 |
< |
return (s >= 0) ? awaitDone(w, false) : s; // block if no work |
| 626 |
> |
private void reportException(int s) { |
| 627 |
> |
if (s == CANCELLED) |
| 628 |
> |
throw new CancellationException(); |
| 629 |
> |
if (s == EXCEPTIONAL) |
| 630 |
> |
rethrow(getThrowableException()); |
| 631 |
|
} |
| 632 |
|
|
| 633 |
|
// public methods |
| 634 |
|
|
| 635 |
|
/** |
| 636 |
< |
* Arranges to asynchronously execute this task. While it is not |
| 637 |
< |
* necessarily enforced, it is a usage error to fork a task more |
| 638 |
< |
* than once unless it has completed and been reinitialized. This |
| 639 |
< |
* method may be invoked only from within ForkJoinTask |
| 640 |
< |
* computations (as may be determined using method {@link |
| 641 |
< |
* #inForkJoinPool}). Attempts to invoke in other contexts result |
| 642 |
< |
* in exceptions or errors, possibly including ClassCastException. |
| 636 |
> |
* Arranges to asynchronously execute this task in the pool the |
| 637 |
> |
* current task is running in, if applicable, or using the {@link |
| 638 |
> |
* ForkJoinPool#commonPool()} if not {@link #inForkJoinPool}. While |
| 639 |
> |
* it is not necessarily enforced, it is a usage error to fork a |
| 640 |
> |
* task more than once unless it has completed and been |
| 641 |
> |
* reinitialized. Subsequent modifications to the state of this |
| 642 |
> |
* task or any data it operates on are not necessarily |
| 643 |
> |
* consistently observable by any thread other than the one |
| 644 |
> |
* executing it unless preceded by a call to {@link #join} or |
| 645 |
> |
* related methods, or a call to {@link #isDone} returning {@code |
| 646 |
> |
* true}. |
| 647 |
|
* |
| 648 |
< |
* @return <code>this</code>, to simplify usage. |
| 648 |
> |
* @return {@code this}, to simplify usage |
| 649 |
|
*/ |
| 650 |
|
public final ForkJoinTask<V> fork() { |
| 651 |
< |
((ForkJoinWorkerThread) Thread.currentThread()) |
| 652 |
< |
.pushTask(this); |
| 651 |
> |
Thread t; |
| 652 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
| 653 |
> |
((ForkJoinWorkerThread)t).workQueue.push(this); |
| 654 |
> |
else |
| 655 |
> |
ForkJoinPool.commonPool.externalPush(this); |
| 656 |
|
return this; |
| 657 |
|
} |
| 658 |
|
|
| 659 |
|
/** |
| 660 |
< |
* Returns the result of the computation when it is ready. |
| 661 |
< |
* This method differs from {@code get} in that abnormal |
| 662 |
< |
* completion results in RuntimeExceptions or Errors, not |
| 663 |
< |
* ExecutionExceptions. |
| 660 |
> |
* Returns the result of the computation when it {@link #isDone is |
| 661 |
> |
* done}. This method differs from {@link #get()} in that |
| 662 |
> |
* abnormal completion results in {@code RuntimeException} or |
| 663 |
> |
* {@code Error}, not {@code ExecutionException}, and that |
| 664 |
> |
* interrupts of the calling thread do <em>not</em> cause the |
| 665 |
> |
* method to abruptly return by throwing {@code |
| 666 |
> |
* InterruptedException}. |
| 667 |
|
* |
| 668 |
|
* @return the computed result |
| 669 |
|
*/ |
| 670 |
|
public final V join() { |
| 671 |
< |
ForkJoinWorkerThread w = getWorker(); |
| 672 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryExec()) |
| 673 |
< |
reportException(awaitDone(w, true)); |
| 671 |
> |
int s; |
| 672 |
> |
if ((s = doJoin() & DONE_MASK) != NORMAL) |
| 673 |
> |
reportException(s); |
| 674 |
|
return getRawResult(); |
| 675 |
|
} |
| 676 |
|
|
| 677 |
|
/** |
| 678 |
|
* Commences performing this task, awaits its completion if |
| 679 |
< |
* necessary, and return its result. |
| 679 |
> |
* necessary, and returns its result, or throws an (unchecked) |
| 680 |
> |
* {@code RuntimeException} or {@code Error} if the underlying |
| 681 |
> |
* computation did so. |
| 682 |
|
* |
| 523 |
– |
* @throws Throwable (a RuntimeException, Error, or unchecked |
| 524 |
– |
* exception) if the underlying computation did so |
| 683 |
|
* @return the computed result |
| 684 |
|
*/ |
| 685 |
|
public final V invoke() { |
| 686 |
< |
if (status >= 0 && tryExec()) |
| 687 |
< |
return getRawResult(); |
| 688 |
< |
else |
| 689 |
< |
return join(); |
| 686 |
> |
int s; |
| 687 |
> |
if ((s = doInvoke() & DONE_MASK) != NORMAL) |
| 688 |
> |
reportException(s); |
| 689 |
> |
return getRawResult(); |
| 690 |
|
} |
| 691 |
|
|
| 692 |
|
/** |
| 693 |
< |
* Forks both tasks, returning when {@code isDone} holds for |
| 694 |
< |
* both of them or an exception is encountered. This method may be |
| 695 |
< |
* invoked only from within ForkJoinTask computations (as may be |
| 696 |
< |
* determined using method {@link #inForkJoinPool}). Attempts to |
| 697 |
< |
* invoke in other contexts result in exceptions or errors, |
| 698 |
< |
* possibly including ClassCastException. |
| 699 |
< |
* |
| 700 |
< |
* @param t1 one task |
| 701 |
< |
* @param t2 the other task |
| 702 |
< |
* @throws NullPointerException if t1 or t2 are null |
| 703 |
< |
* @throws RuntimeException or Error if either task did so |
| 693 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
| 694 |
> |
* each task or an (unchecked) exception is encountered, in which |
| 695 |
> |
* case the exception is rethrown. If more than one task |
| 696 |
> |
* encounters an exception, then this method throws any one of |
| 697 |
> |
* these exceptions. If any task encounters an exception, the |
| 698 |
> |
* other may be cancelled. However, the execution status of |
| 699 |
> |
* individual tasks is not guaranteed upon exceptional return. The |
| 700 |
> |
* status of each task may be obtained using {@link |
| 701 |
> |
* #getException()} and related methods to check if they have been |
| 702 |
> |
* cancelled, completed normally or exceptionally, or left |
| 703 |
> |
* unprocessed. |
| 704 |
> |
* |
| 705 |
> |
* @param t1 the first task |
| 706 |
> |
* @param t2 the second task |
| 707 |
> |
* @throws NullPointerException if any task is null |
| 708 |
|
*/ |
| 709 |
< |
public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) { |
| 709 |
> |
public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) { |
| 710 |
> |
int s1, s2; |
| 711 |
|
t2.fork(); |
| 712 |
< |
t1.invoke(); |
| 713 |
< |
t2.join(); |
| 712 |
> |
if ((s1 = t1.doInvoke() & DONE_MASK) != NORMAL) |
| 713 |
> |
t1.reportException(s1); |
| 714 |
> |
if ((s2 = t2.doJoin() & DONE_MASK) != NORMAL) |
| 715 |
> |
t2.reportException(s2); |
| 716 |
|
} |
| 717 |
|
|
| 718 |
|
/** |
| 719 |
< |
* Forks the given tasks, returning when {@code isDone} holds |
| 720 |
< |
* for all of them. If any task encounters an exception, others |
| 721 |
< |
* may be cancelled. This method may be invoked only from within |
| 722 |
< |
* ForkJoinTask computations (as may be determined using method |
| 723 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
| 724 |
< |
* result in exceptions or errors, possibly including |
| 725 |
< |
* ClassCastException. |
| 719 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
| 720 |
> |
* each task or an (unchecked) exception is encountered, in which |
| 721 |
> |
* case the exception is rethrown. If more than one task |
| 722 |
> |
* encounters an exception, then this method throws any one of |
| 723 |
> |
* these exceptions. If any task encounters an exception, others |
| 724 |
> |
* may be cancelled. However, the execution status of individual |
| 725 |
> |
* tasks is not guaranteed upon exceptional return. The status of |
| 726 |
> |
* each task may be obtained using {@link #getException()} and |
| 727 |
> |
* related methods to check if they have been cancelled, completed |
| 728 |
> |
* normally or exceptionally, or left unprocessed. |
| 729 |
|
* |
| 730 |
< |
* @param tasks the array of tasks |
| 731 |
< |
* @throws NullPointerException if tasks or any element are null |
| 564 |
< |
* @throws RuntimeException or Error if any task did so |
| 730 |
> |
* @param tasks the tasks |
| 731 |
> |
* @throws NullPointerException if any task is null |
| 732 |
|
*/ |
| 733 |
|
public static void invokeAll(ForkJoinTask<?>... tasks) { |
| 734 |
|
Throwable ex = null; |
| 741 |
|
} |
| 742 |
|
else if (i != 0) |
| 743 |
|
t.fork(); |
| 744 |
< |
else { |
| 745 |
< |
t.quietlyInvoke(); |
| 579 |
< |
if (ex == null) |
| 580 |
< |
ex = t.getException(); |
| 581 |
< |
} |
| 744 |
> |
else if (t.doInvoke() < NORMAL && ex == null) |
| 745 |
> |
ex = t.getException(); |
| 746 |
|
} |
| 747 |
|
for (int i = 1; i <= last; ++i) { |
| 748 |
|
ForkJoinTask<?> t = tasks[i]; |
| 749 |
|
if (t != null) { |
| 750 |
|
if (ex != null) |
| 751 |
|
t.cancel(false); |
| 752 |
< |
else { |
| 753 |
< |
t.quietlyJoin(); |
| 590 |
< |
if (ex == null) |
| 591 |
< |
ex = t.getException(); |
| 592 |
< |
} |
| 752 |
> |
else if (t.doJoin() < NORMAL) |
| 753 |
> |
ex = t.getException(); |
| 754 |
|
} |
| 755 |
|
} |
| 756 |
|
if (ex != null) |
| 757 |
< |
rethrowException(ex); |
| 757 |
> |
rethrow(ex); |
| 758 |
|
} |
| 759 |
|
|
| 760 |
|
/** |
| 761 |
< |
* Forks all tasks in the collection, returning when |
| 762 |
< |
* {@code isDone} holds for all of them. If any task |
| 763 |
< |
* encounters an exception, others may be cancelled. This method |
| 764 |
< |
* may be invoked only from within ForkJoinTask computations (as |
| 765 |
< |
* may be determined using method {@link |
| 766 |
< |
* #inForkJoinPool}). Attempts to invoke in other contexts result |
| 767 |
< |
* in exceptions or errors, possibly including ClassCastException. |
| 761 |
> |
* Forks all tasks in the specified collection, returning when |
| 762 |
> |
* {@code isDone} holds for each task or an (unchecked) exception |
| 763 |
> |
* is encountered, in which case the exception is rethrown. If |
| 764 |
> |
* more than one task encounters an exception, then this method |
| 765 |
> |
* throws any one of these exceptions. If any task encounters an |
| 766 |
> |
* exception, others may be cancelled. However, the execution |
| 767 |
> |
* status of individual tasks is not guaranteed upon exceptional |
| 768 |
> |
* return. The status of each task may be obtained using {@link |
| 769 |
> |
* #getException()} and related methods to check if they have been |
| 770 |
> |
* cancelled, completed normally or exceptionally, or left |
| 771 |
> |
* unprocessed. |
| 772 |
|
* |
| 773 |
|
* @param tasks the collection of tasks |
| 774 |
|
* @return the tasks argument, to simplify usage |
| 775 |
|
* @throws NullPointerException if tasks or any element are null |
| 611 |
– |
* @throws RuntimeException or Error if any task did so |
| 776 |
|
*/ |
| 777 |
|
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
| 778 |
< |
if (!(tasks instanceof List<?>)) { |
| 778 |
> |
if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) { |
| 779 |
|
invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()])); |
| 780 |
|
return tasks; |
| 781 |
|
} |
| 792 |
|
} |
| 793 |
|
else if (i != 0) |
| 794 |
|
t.fork(); |
| 795 |
< |
else { |
| 796 |
< |
t.quietlyInvoke(); |
| 633 |
< |
if (ex == null) |
| 634 |
< |
ex = t.getException(); |
| 635 |
< |
} |
| 795 |
> |
else if (t.doInvoke() < NORMAL && ex == null) |
| 796 |
> |
ex = t.getException(); |
| 797 |
|
} |
| 798 |
|
for (int i = 1; i <= last; ++i) { |
| 799 |
|
ForkJoinTask<?> t = ts.get(i); |
| 800 |
|
if (t != null) { |
| 801 |
|
if (ex != null) |
| 802 |
|
t.cancel(false); |
| 803 |
< |
else { |
| 804 |
< |
t.quietlyJoin(); |
| 644 |
< |
if (ex == null) |
| 645 |
< |
ex = t.getException(); |
| 646 |
< |
} |
| 803 |
> |
else if (t.doJoin() < NORMAL) |
| 804 |
> |
ex = t.getException(); |
| 805 |
|
} |
| 806 |
|
} |
| 807 |
|
if (ex != null) |
| 808 |
< |
rethrowException(ex); |
| 808 |
> |
rethrow(ex); |
| 809 |
|
return tasks; |
| 810 |
|
} |
| 811 |
|
|
| 812 |
|
/** |
| 813 |
< |
* Returns true if the computation performed by this task has |
| 814 |
< |
* completed (or has been cancelled). |
| 813 |
> |
* Attempts to cancel execution of this task. This attempt will |
| 814 |
> |
* fail if the task has already completed or could not be |
| 815 |
> |
* cancelled for some other reason. If successful, and this task |
| 816 |
> |
* has not started when {@code cancel} is called, execution of |
| 817 |
> |
* this task is suppressed. After this method returns |
| 818 |
> |
* successfully, unless there is an intervening call to {@link |
| 819 |
> |
* #reinitialize}, subsequent calls to {@link #isCancelled}, |
| 820 |
> |
* {@link #isDone}, and {@code cancel} will return {@code true} |
| 821 |
> |
* and calls to {@link #join} and related methods will result in |
| 822 |
> |
* {@code CancellationException}. |
| 823 |
|
* |
| 824 |
< |
* @return true if this computation has completed |
| 824 |
> |
* <p>This method may be overridden in subclasses, but if so, must |
| 825 |
> |
* still ensure that these properties hold. In particular, the |
| 826 |
> |
* {@code cancel} method itself must not throw exceptions. |
| 827 |
> |
* |
| 828 |
> |
* <p>This method is designed to be invoked by <em>other</em> |
| 829 |
> |
* tasks. To terminate the current task, you can just return or |
| 830 |
> |
* throw an unchecked exception from its computation method, or |
| 831 |
> |
* invoke {@link #completeExceptionally}. |
| 832 |
> |
* |
| 833 |
> |
* @param mayInterruptIfRunning this value has no effect in the |
| 834 |
> |
* default implementation because interrupts are not used to |
| 835 |
> |
* control cancellation. |
| 836 |
> |
* |
| 837 |
> |
* @return {@code true} if this task is now cancelled |
| 838 |
|
*/ |
| 839 |
+ |
public boolean cancel(boolean mayInterruptIfRunning) { |
| 840 |
+ |
return (setCompletion(CANCELLED) & DONE_MASK) == CANCELLED; |
| 841 |
+ |
} |
| 842 |
+ |
|
| 843 |
|
public final boolean isDone() { |
| 844 |
|
return status < 0; |
| 845 |
|
} |
| 846 |
|
|
| 664 |
– |
/** |
| 665 |
– |
* Returns true if this task was cancelled. |
| 666 |
– |
* |
| 667 |
– |
* @return true if this task was cancelled |
| 668 |
– |
*/ |
| 847 |
|
public final boolean isCancelled() { |
| 848 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
| 848 |
> |
return (status & DONE_MASK) == CANCELLED; |
| 849 |
|
} |
| 850 |
|
|
| 851 |
|
/** |
| 852 |
< |
* Asserts that the results of this task's computation will not be |
| 675 |
< |
* used. If a cancellation occurs before attempting to execute this |
| 676 |
< |
* task, then execution will be suppressed, {@code isCancelled} |
| 677 |
< |
* will report true, and {@code join} will result in a |
| 678 |
< |
* {@code CancellationException} being thrown. Otherwise, when |
| 679 |
< |
* cancellation races with completion, there are no guarantees |
| 680 |
< |
* about whether {@code isCancelled} will report true, whether |
| 681 |
< |
* {@code join} will return normally or via an exception, or |
| 682 |
< |
* whether these behaviors will remain consistent upon repeated |
| 683 |
< |
* invocation. |
| 684 |
< |
* |
| 685 |
< |
* <p>This method may be overridden in subclasses, but if so, must |
| 686 |
< |
* still ensure that these minimal properties hold. In particular, |
| 687 |
< |
* the cancel method itself must not throw exceptions. |
| 688 |
< |
* |
| 689 |
< |
* <p> This method is designed to be invoked by <em>other</em> |
| 690 |
< |
* tasks. To terminate the current task, you can just return or |
| 691 |
< |
* throw an unchecked exception from its computation method, or |
| 692 |
< |
* invoke {@code completeExceptionally}. |
| 852 |
> |
* Returns {@code true} if this task threw an exception or was cancelled. |
| 853 |
|
* |
| 854 |
< |
* @param mayInterruptIfRunning this value is ignored in the |
| 695 |
< |
* default implementation because tasks are not in general |
| 696 |
< |
* cancelled via interruption |
| 697 |
< |
* |
| 698 |
< |
* @return true if this task is now cancelled |
| 854 |
> |
* @return {@code true} if this task threw an exception or was cancelled |
| 855 |
|
*/ |
| 856 |
< |
public boolean cancel(boolean mayInterruptIfRunning) { |
| 857 |
< |
setCompletion(CANCELLED); |
| 702 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
| 856 |
> |
public final boolean isCompletedAbnormally() { |
| 857 |
> |
return status < NORMAL; |
| 858 |
|
} |
| 859 |
|
|
| 860 |
|
/** |
| 861 |
< |
* Returns true if this task threw an exception or was cancelled. |
| 861 |
> |
* Returns {@code true} if this task completed without throwing an |
| 862 |
> |
* exception and was not cancelled. |
| 863 |
|
* |
| 864 |
< |
* @return true if this task threw an exception or was cancelled |
| 864 |
> |
* @return {@code true} if this task completed without throwing an |
| 865 |
> |
* exception and was not cancelled |
| 866 |
|
*/ |
| 867 |
< |
public final boolean isCompletedAbnormally() { |
| 868 |
< |
return (status & COMPLETION_MASK) < NORMAL; |
| 867 |
> |
public final boolean isCompletedNormally() { |
| 868 |
> |
return (status & DONE_MASK) == NORMAL; |
| 869 |
|
} |
| 870 |
|
|
| 871 |
|
/** |
| 872 |
|
* Returns the exception thrown by the base computation, or a |
| 873 |
< |
* CancellationException if cancelled, or null if none or if the |
| 874 |
< |
* method has not yet completed. |
| 873 |
> |
* {@code CancellationException} if cancelled, or {@code null} if |
| 874 |
> |
* none or if the method has not yet completed. |
| 875 |
|
* |
| 876 |
< |
* @return the exception, or null if none |
| 876 |
> |
* @return the exception, or {@code null} if none |
| 877 |
|
*/ |
| 878 |
|
public final Throwable getException() { |
| 879 |
< |
int s = status & COMPLETION_MASK; |
| 880 |
< |
if (s >= NORMAL) |
| 881 |
< |
return null; |
| 882 |
< |
if (s == CANCELLED) |
| 726 |
< |
return new CancellationException(); |
| 727 |
< |
return exceptionMap.get(this); |
| 879 |
> |
int s = status & DONE_MASK; |
| 880 |
> |
return ((s >= NORMAL) ? null : |
| 881 |
> |
(s == CANCELLED) ? new CancellationException() : |
| 882 |
> |
getThrowableException()); |
| 883 |
|
} |
| 884 |
|
|
| 885 |
|
/** |
| 888 |
|
* {@code join} and related operations. This method may be used |
| 889 |
|
* to induce exceptions in asynchronous tasks, or to force |
| 890 |
|
* completion of tasks that would not otherwise complete. Its use |
| 891 |
< |
* in other situations is likely to be wrong. This method is |
| 891 |
> |
* in other situations is discouraged. This method is |
| 892 |
|
* overridable, but overridden versions must invoke {@code super} |
| 893 |
|
* implementation to maintain guarantees. |
| 894 |
|
* |
| 895 |
< |
* @param ex the exception to throw. If this exception is |
| 896 |
< |
* not a RuntimeException or Error, the actual exception thrown |
| 897 |
< |
* will be a RuntimeException with cause ex. |
| 895 |
> |
* @param ex the exception to throw. If this exception is not a |
| 896 |
> |
* {@code RuntimeException} or {@code Error}, the actual exception |
| 897 |
> |
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
| 898 |
|
*/ |
| 899 |
|
public void completeExceptionally(Throwable ex) { |
| 900 |
< |
setDoneExceptionally((ex instanceof RuntimeException) || |
| 901 |
< |
(ex instanceof Error) ? ex : |
| 902 |
< |
new RuntimeException(ex)); |
| 900 |
> |
setExceptionalCompletion((ex instanceof RuntimeException) || |
| 901 |
> |
(ex instanceof Error) ? ex : |
| 902 |
> |
new RuntimeException(ex)); |
| 903 |
|
} |
| 904 |
|
|
| 905 |
|
/** |
| 906 |
|
* Completes this task, and if not already aborted or cancelled, |
| 907 |
< |
* returning a {@code null} result upon {@code join} and related |
| 908 |
< |
* operations. This method may be used to provide results for |
| 909 |
< |
* asynchronous tasks, or to provide alternative handling for |
| 910 |
< |
* tasks that would not otherwise complete normally. Its use in |
| 911 |
< |
* other situations is likely to be wrong. This method is |
| 912 |
< |
* overridable, but overridden versions must invoke {@code super} |
| 913 |
< |
* implementation to maintain guarantees. |
| 907 |
> |
* returning the given value as the result of subsequent |
| 908 |
> |
* invocations of {@code join} and related operations. This method |
| 909 |
> |
* may be used to provide results for asynchronous tasks, or to |
| 910 |
> |
* provide alternative handling for tasks that would not otherwise |
| 911 |
> |
* complete normally. Its use in other situations is |
| 912 |
> |
* discouraged. This method is overridable, but overridden |
| 913 |
> |
* versions must invoke {@code super} implementation to maintain |
| 914 |
> |
* guarantees. |
| 915 |
|
* |
| 916 |
|
* @param value the result value for this task |
| 917 |
|
*/ |
| 919 |
|
try { |
| 920 |
|
setRawResult(value); |
| 921 |
|
} catch (Throwable rex) { |
| 922 |
< |
setDoneExceptionally(rex); |
| 922 |
> |
setExceptionalCompletion(rex); |
| 923 |
|
return; |
| 924 |
|
} |
| 925 |
< |
setNormalCompletion(); |
| 925 |
> |
setCompletion(NORMAL); |
| 926 |
|
} |
| 927 |
|
|
| 928 |
< |
public final V get() throws InterruptedException, ExecutionException { |
| 929 |
< |
ForkJoinWorkerThread w = getWorker(); |
| 930 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
| 931 |
< |
awaitDone(w, true); |
| 932 |
< |
return reportFutureResult(); |
| 933 |
< |
} |
| 934 |
< |
|
| 935 |
< |
public final V get(long timeout, TimeUnit unit) |
| 936 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
| 937 |
< |
ForkJoinWorkerThread w = getWorker(); |
| 782 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
| 783 |
< |
awaitDone(w, unit.toNanos(timeout)); |
| 784 |
< |
return reportTimedFutureResult(); |
| 928 |
> |
/** |
| 929 |
> |
* Completes this task normally without setting a value. The most |
| 930 |
> |
* recent value established by {@link #setRawResult} (or {@code |
| 931 |
> |
* null} by default) will be returned as the result of subsequent |
| 932 |
> |
* invocations of {@code join} and related operations. |
| 933 |
> |
* |
| 934 |
> |
* @since 1.8 |
| 935 |
> |
*/ |
| 936 |
> |
public final void quietlyComplete() { |
| 937 |
> |
setCompletion(NORMAL); |
| 938 |
|
} |
| 939 |
|
|
| 940 |
|
/** |
| 941 |
< |
* Possibly executes other tasks until this task is ready, then |
| 942 |
< |
* returns the result of the computation. This method may be more |
| 790 |
< |
* efficient than {@code join}, but is only applicable when |
| 791 |
< |
* there are no potential dependencies between continuation of the |
| 792 |
< |
* current task and that of any other task that might be executed |
| 793 |
< |
* while helping. (This usually holds for pure divide-and-conquer |
| 794 |
< |
* tasks). This method may be invoked only from within |
| 795 |
< |
* ForkJoinTask computations (as may be determined using method |
| 796 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
| 797 |
< |
* result in exceptions or errors, possibly including |
| 798 |
< |
* ClassCastException. |
| 941 |
> |
* Waits if necessary for the computation to complete, and then |
| 942 |
> |
* retrieves its result. |
| 943 |
|
* |
| 944 |
|
* @return the computed result |
| 945 |
+ |
* @throws CancellationException if the computation was cancelled |
| 946 |
+ |
* @throws ExecutionException if the computation threw an |
| 947 |
+ |
* exception |
| 948 |
+ |
* @throws InterruptedException if the current thread is not a |
| 949 |
+ |
* member of a ForkJoinPool and was interrupted while waiting |
| 950 |
|
*/ |
| 951 |
< |
public final V helpJoin() { |
| 952 |
< |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread(); |
| 953 |
< |
if (status < 0 || !w.unpushTask(this) || !tryExec()) |
| 954 |
< |
reportException(busyJoin(w)); |
| 951 |
> |
public final V get() throws InterruptedException, ExecutionException { |
| 952 |
> |
int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ? |
| 953 |
> |
doJoin() : externalInterruptibleAwaitDone(); |
| 954 |
> |
Throwable ex; |
| 955 |
> |
if ((s &= DONE_MASK) == CANCELLED) |
| 956 |
> |
throw new CancellationException(); |
| 957 |
> |
if (s == EXCEPTIONAL && (ex = getThrowableException()) != null) |
| 958 |
> |
throw new ExecutionException(ex); |
| 959 |
|
return getRawResult(); |
| 960 |
|
} |
| 961 |
|
|
| 962 |
|
/** |
| 963 |
< |
* Possibly executes other tasks until this task is ready. This |
| 964 |
< |
* method may be invoked only from within ForkJoinTask |
| 965 |
< |
* computations (as may be determined using method {@link |
| 966 |
< |
* #inForkJoinPool}). Attempts to invoke in other contexts result |
| 967 |
< |
* in exceptions or errors, possibly including ClassCastException. |
| 963 |
> |
* Waits if necessary for at most the given time for the computation |
| 964 |
> |
* to complete, and then retrieves its result, if available. |
| 965 |
> |
* |
| 966 |
> |
* @param timeout the maximum time to wait |
| 967 |
> |
* @param unit the time unit of the timeout argument |
| 968 |
> |
* @return the computed result |
| 969 |
> |
* @throws CancellationException if the computation was cancelled |
| 970 |
> |
* @throws ExecutionException if the computation threw an |
| 971 |
> |
* exception |
| 972 |
> |
* @throws InterruptedException if the current thread is not a |
| 973 |
> |
* member of a ForkJoinPool and was interrupted while waiting |
| 974 |
> |
* @throws TimeoutException if the wait timed out |
| 975 |
|
*/ |
| 976 |
< |
public final void quietlyHelpJoin() { |
| 977 |
< |
if (status >= 0) { |
| 978 |
< |
ForkJoinWorkerThread w = |
| 979 |
< |
(ForkJoinWorkerThread) Thread.currentThread(); |
| 980 |
< |
if (!w.unpushTask(this) || !tryQuietlyInvoke()) |
| 981 |
< |
busyJoin(w); |
| 976 |
> |
public final V get(long timeout, TimeUnit unit) |
| 977 |
> |
throws InterruptedException, ExecutionException, TimeoutException { |
| 978 |
> |
if (Thread.interrupted()) |
| 979 |
> |
throw new InterruptedException(); |
| 980 |
> |
// Messy in part because we measure in nanosecs, but wait in millisecs |
| 981 |
> |
int s; long ns, ms; |
| 982 |
> |
if ((s = status) >= 0 && (ns = unit.toNanos(timeout)) > 0L) { |
| 983 |
> |
long deadline = System.nanoTime() + ns; |
| 984 |
> |
ForkJoinPool p = null; |
| 985 |
> |
ForkJoinPool.WorkQueue w = null; |
| 986 |
> |
Thread t = Thread.currentThread(); |
| 987 |
> |
if (t instanceof ForkJoinWorkerThread) { |
| 988 |
> |
ForkJoinWorkerThread wt = (ForkJoinWorkerThread)t; |
| 989 |
> |
p = wt.pool; |
| 990 |
> |
w = wt.workQueue; |
| 991 |
> |
p.helpJoinOnce(w, this); // no retries on failure |
| 992 |
> |
} |
| 993 |
> |
else |
| 994 |
> |
ForkJoinPool.externalHelpJoin(this); |
| 995 |
> |
boolean canBlock = false; |
| 996 |
> |
boolean interrupted = false; |
| 997 |
> |
try { |
| 998 |
> |
while ((s = status) >= 0) { |
| 999 |
> |
if (w != null && w.qlock < 0) |
| 1000 |
> |
cancelIgnoringExceptions(this); |
| 1001 |
> |
else if (!canBlock) { |
| 1002 |
> |
if (p == null || p.tryCompensate()) |
| 1003 |
> |
canBlock = true; |
| 1004 |
> |
} |
| 1005 |
> |
else { |
| 1006 |
> |
if ((ms = TimeUnit.NANOSECONDS.toMillis(ns)) > 0L && |
| 1007 |
> |
U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) { |
| 1008 |
> |
synchronized (this) { |
| 1009 |
> |
if (status >= 0) { |
| 1010 |
> |
try { |
| 1011 |
> |
wait(ms); |
| 1012 |
> |
} catch (InterruptedException ie) { |
| 1013 |
> |
if (p == null) |
| 1014 |
> |
interrupted = true; |
| 1015 |
> |
} |
| 1016 |
> |
} |
| 1017 |
> |
else |
| 1018 |
> |
notifyAll(); |
| 1019 |
> |
} |
| 1020 |
> |
} |
| 1021 |
> |
if ((s = status) < 0 || interrupted || |
| 1022 |
> |
(ns = deadline - System.nanoTime()) <= 0L) |
| 1023 |
> |
break; |
| 1024 |
> |
} |
| 1025 |
> |
} |
| 1026 |
> |
} finally { |
| 1027 |
> |
if (p != null && canBlock) |
| 1028 |
> |
p.incrementActiveCount(); |
| 1029 |
> |
} |
| 1030 |
> |
if (interrupted) |
| 1031 |
> |
throw new InterruptedException(); |
| 1032 |
> |
} |
| 1033 |
> |
if ((s &= DONE_MASK) != NORMAL) { |
| 1034 |
> |
Throwable ex; |
| 1035 |
> |
if (s == CANCELLED) |
| 1036 |
> |
throw new CancellationException(); |
| 1037 |
> |
if (s != EXCEPTIONAL) |
| 1038 |
> |
throw new TimeoutException(); |
| 1039 |
> |
if ((ex = getThrowableException()) != null) |
| 1040 |
> |
throw new ExecutionException(ex); |
| 1041 |
|
} |
| 1042 |
+ |
return getRawResult(); |
| 1043 |
|
} |
| 1044 |
|
|
| 1045 |
|
/** |
| 1046 |
< |
* Joins this task, without returning its result or throwing an |
| 1046 |
> |
* Joins this task, without returning its result or throwing its |
| 1047 |
|
* exception. This method may be useful when processing |
| 1048 |
|
* collections of tasks when some have been cancelled or otherwise |
| 1049 |
|
* known to have aborted. |
| 1050 |
|
*/ |
| 1051 |
|
public final void quietlyJoin() { |
| 1052 |
< |
if (status >= 0) { |
| 833 |
< |
ForkJoinWorkerThread w = getWorker(); |
| 834 |
< |
if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke()) |
| 835 |
< |
awaitDone(w, true); |
| 836 |
< |
} |
| 1052 |
> |
doJoin(); |
| 1053 |
|
} |
| 1054 |
|
|
| 1055 |
|
/** |
| 1056 |
|
* Commences performing this task and awaits its completion if |
| 1057 |
< |
* necessary, without returning its result or throwing an |
| 1058 |
< |
* exception. This method may be useful when processing |
| 843 |
< |
* collections of tasks when some have been cancelled or otherwise |
| 844 |
< |
* known to have aborted. |
| 1057 |
> |
* necessary, without returning its result or throwing its |
| 1058 |
> |
* exception. |
| 1059 |
|
*/ |
| 1060 |
|
public final void quietlyInvoke() { |
| 1061 |
< |
if (status >= 0 && !tryQuietlyInvoke()) |
| 848 |
< |
quietlyJoin(); |
| 1061 |
> |
doInvoke(); |
| 1062 |
|
} |
| 1063 |
|
|
| 1064 |
|
/** |
| 1065 |
|
* Possibly executes tasks until the pool hosting the current task |
| 1066 |
< |
* {@link ForkJoinPool#isQuiescent}. This method may be of use in |
| 1067 |
< |
* designs in which many tasks are forked, but none are explicitly |
| 1068 |
< |
* joined, instead executing them until all are processed. |
| 1066 |
> |
* {@link ForkJoinPool#isQuiescent is quiescent}. This method may |
| 1067 |
> |
* be of use in designs in which many tasks are forked, but none |
| 1068 |
> |
* are explicitly joined, instead executing them until all are |
| 1069 |
> |
* processed. |
| 1070 |
|
*/ |
| 1071 |
|
public static void helpQuiesce() { |
| 1072 |
< |
((ForkJoinWorkerThread) Thread.currentThread()) |
| 1073 |
< |
.helpQuiescePool(); |
| 1072 |
> |
Thread t; |
| 1073 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) { |
| 1074 |
> |
ForkJoinWorkerThread wt = (ForkJoinWorkerThread)t; |
| 1075 |
> |
wt.pool.helpQuiescePool(wt.workQueue); |
| 1076 |
> |
} |
| 1077 |
> |
else |
| 1078 |
> |
ForkJoinPool.externalHelpQuiescePool(); |
| 1079 |
|
} |
| 1080 |
|
|
| 1081 |
|
/** |
| 1084 |
|
* this task, but only if reuse occurs when this task has either |
| 1085 |
|
* never been forked, or has been forked, then completed and all |
| 1086 |
|
* outstanding joins of this task have also completed. Effects |
| 1087 |
< |
* under any other usage conditions are not guaranteed, and are |
| 1088 |
< |
* almost surely wrong. This method may be useful when executing |
| 1087 |
> |
* under any other usage conditions are not guaranteed. |
| 1088 |
> |
* This method may be useful when executing |
| 1089 |
|
* pre-constructed trees of subtasks in loops. |
| 1090 |
+ |
* |
| 1091 |
+ |
* <p>Upon completion of this method, {@code isDone()} reports |
| 1092 |
+ |
* {@code false}, and {@code getException()} reports {@code |
| 1093 |
+ |
* null}. However, the value returned by {@code getRawResult} is |
| 1094 |
+ |
* unaffected. To clear this value, you can invoke {@code |
| 1095 |
+ |
* setRawResult(null)}. |
| 1096 |
|
*/ |
| 1097 |
|
public void reinitialize() { |
| 1098 |
< |
if ((status & COMPLETION_MASK) == EXCEPTIONAL) |
| 1099 |
< |
exceptionMap.remove(this); |
| 1100 |
< |
status = 0; |
| 1098 |
> |
if ((status & DONE_MASK) == EXCEPTIONAL) |
| 1099 |
> |
clearExceptionalCompletion(); |
| 1100 |
> |
else |
| 1101 |
> |
status = 0; |
| 1102 |
|
} |
| 1103 |
|
|
| 1104 |
|
/** |
| 1105 |
|
* Returns the pool hosting the current task execution, or null |
| 1106 |
|
* if this task is executing outside of any ForkJoinPool. |
| 1107 |
|
* |
| 1108 |
< |
* @return the pool, or null if none |
| 1108 |
> |
* @see #inForkJoinPool |
| 1109 |
> |
* @return the pool, or {@code null} if none |
| 1110 |
|
*/ |
| 1111 |
|
public static ForkJoinPool getPool() { |
| 1112 |
|
Thread t = Thread.currentThread(); |
| 1115 |
|
} |
| 1116 |
|
|
| 1117 |
|
/** |
| 1118 |
< |
* Returns {@code true} if the current thread is executing as a |
| 1119 |
< |
* ForkJoinPool computation. |
| 1118 |
> |
* Returns {@code true} if the current thread is a {@link |
| 1119 |
> |
* ForkJoinWorkerThread} executing as a ForkJoinPool computation. |
| 1120 |
|
* |
| 1121 |
< |
* @return {@code true} if the current thread is executing as a |
| 1122 |
< |
* ForkJoinPool computation, or false otherwise |
| 1121 |
> |
* @return {@code true} if the current thread is a {@link |
| 1122 |
> |
* ForkJoinWorkerThread} executing as a ForkJoinPool computation, |
| 1123 |
> |
* or {@code false} otherwise |
| 1124 |
|
*/ |
| 1125 |
|
public static boolean inForkJoinPool() { |
| 1126 |
|
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
| 1128 |
|
|
| 1129 |
|
/** |
| 1130 |
|
* Tries to unschedule this task for execution. This method will |
| 1131 |
< |
* typically succeed if this task is the most recently forked task |
| 1132 |
< |
* by the current thread, and has not commenced executing in |
| 1133 |
< |
* another thread. This method may be useful when arranging |
| 1134 |
< |
* alternative local processing of tasks that could have been, but |
| 1135 |
< |
* were not, stolen. This method may be invoked only from within |
| 908 |
< |
* ForkJoinTask computations (as may be determined using method |
| 909 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
| 910 |
< |
* result in exceptions or errors, possibly including |
| 911 |
< |
* ClassCastException. |
| 1131 |
> |
* typically (but is not guaranteed to) succeed if this task is |
| 1132 |
> |
* the most recently forked task by the current thread, and has |
| 1133 |
> |
* not commenced executing in another thread. This method may be |
| 1134 |
> |
* useful when arranging alternative local processing of tasks |
| 1135 |
> |
* that could have been, but were not, stolen. |
| 1136 |
|
* |
| 1137 |
< |
* @return true if unforked |
| 1137 |
> |
* @return {@code true} if unforked |
| 1138 |
|
*/ |
| 1139 |
|
public boolean tryUnfork() { |
| 1140 |
< |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
| 1141 |
< |
.unpushTask(this); |
| 1140 |
> |
Thread t; |
| 1141 |
> |
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
| 1142 |
> |
((ForkJoinWorkerThread)t).workQueue.tryUnpush(this) : |
| 1143 |
> |
ForkJoinPool.tryExternalUnpush(this)); |
| 1144 |
|
} |
| 1145 |
|
|
| 1146 |
|
/** |
| 1152 |
|
* @return the number of tasks |
| 1153 |
|
*/ |
| 1154 |
|
public static int getQueuedTaskCount() { |
| 1155 |
< |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
| 1156 |
< |
.getQueueSize(); |
| 1155 |
> |
Thread t; ForkJoinPool.WorkQueue q; |
| 1156 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
| 1157 |
> |
q = ((ForkJoinWorkerThread)t).workQueue; |
| 1158 |
> |
else |
| 1159 |
> |
q = ForkJoinPool.commonSubmitterQueue(); |
| 1160 |
> |
return (q == null) ? 0 : q.queueSize(); |
| 1161 |
|
} |
| 1162 |
|
|
| 1163 |
|
/** |
| 1164 |
|
* Returns an estimate of how many more locally queued tasks are |
| 1165 |
|
* held by the current worker thread than there are other worker |
| 1166 |
< |
* threads that might steal them. This value may be useful for |
| 1166 |
> |
* threads that might steal them, or zero if this thread is not |
| 1167 |
> |
* operating in a ForkJoinPool. This value may be useful for |
| 1168 |
|
* heuristic decisions about whether to fork other tasks. In many |
| 1169 |
|
* usages of ForkJoinTasks, at steady state, each worker should |
| 1170 |
|
* aim to maintain a small constant surplus (for example, 3) of |
| 1174 |
|
* @return the surplus number of tasks, which may be negative |
| 1175 |
|
*/ |
| 1176 |
|
public static int getSurplusQueuedTaskCount() { |
| 1177 |
< |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
| 947 |
< |
.getEstimatedSurplusTaskCount(); |
| 1177 |
> |
return ForkJoinPool.getSurplusQueuedTaskCount(); |
| 1178 |
|
} |
| 1179 |
|
|
| 1180 |
|
// Extension methods |
| 1181 |
|
|
| 1182 |
|
/** |
| 1183 |
< |
* Returns the result that would be returned by {@code join}, |
| 1184 |
< |
* even if this task completed abnormally, or null if this task is |
| 1185 |
< |
* not known to have been completed. This method is designed to |
| 1186 |
< |
* aid debugging, as well as to support extensions. Its use in any |
| 1187 |
< |
* other context is discouraged. |
| 1183 |
> |
* Returns the result that would be returned by {@link #join}, even |
| 1184 |
> |
* if this task completed abnormally, or {@code null} if this task |
| 1185 |
> |
* is not known to have been completed. This method is designed |
| 1186 |
> |
* to aid debugging, as well as to support extensions. Its use in |
| 1187 |
> |
* any other context is discouraged. |
| 1188 |
|
* |
| 1189 |
< |
* @return the result, or null if not completed |
| 1189 |
> |
* @return the result, or {@code null} if not completed |
| 1190 |
|
*/ |
| 1191 |
|
public abstract V getRawResult(); |
| 1192 |
|
|
| 1200 |
|
protected abstract void setRawResult(V value); |
| 1201 |
|
|
| 1202 |
|
/** |
| 1203 |
< |
* Immediately performs the base action of this task. This method |
| 1204 |
< |
* is designed to support extensions, and should not in general be |
| 1205 |
< |
* called otherwise. The return value controls whether this task |
| 1206 |
< |
* is considered to be done normally. It may return false in |
| 1203 |
> |
* Immediately performs the base action of this task and returns |
| 1204 |
> |
* true if, upon return from this method, this task is guaranteed |
| 1205 |
> |
* to have completed normally. This method may return false |
| 1206 |
> |
* otherwise, to indicate that this task is not necessarily |
| 1207 |
> |
* complete (or is not known to be complete), for example in |
| 1208 |
|
* asynchronous actions that require explicit invocations of |
| 1209 |
< |
* {@code complete} to become joinable. It may throw exceptions |
| 1210 |
< |
* to indicate abnormal exit. |
| 1209 |
> |
* completion methods. This method may also throw an (unchecked) |
| 1210 |
> |
* exception to indicate abnormal exit. This method is designed to |
| 1211 |
> |
* support extensions, and should not in general be called |
| 1212 |
> |
* otherwise. |
| 1213 |
|
* |
| 1214 |
< |
* @return true if completed normally |
| 982 |
< |
* @throws Error or RuntimeException if encountered during computation |
| 1214 |
> |
* @return {@code true} if this task is known to have completed normally |
| 1215 |
|
*/ |
| 1216 |
|
protected abstract boolean exec(); |
| 1217 |
|
|
| 1218 |
|
/** |
| 1219 |
< |
* Returns, but does not unschedule or execute, the task queued by |
| 1220 |
< |
* the current thread but not yet executed, if one is |
| 1219 |
> |
* Returns, but does not unschedule or execute, a task queued by |
| 1220 |
> |
* the current thread but not yet executed, if one is immediately |
| 1221 |
|
* available. There is no guarantee that this task will actually |
| 1222 |
< |
* be polled or executed next. This method is designed primarily |
| 1223 |
< |
* to support extensions, and is unlikely to be useful otherwise. |
| 1224 |
< |
* This method may be invoked only from within ForkJoinTask |
| 1225 |
< |
* computations (as may be determined using method {@link |
| 1226 |
< |
* #inForkJoinPool}). Attempts to invoke in other contexts result |
| 995 |
< |
* in exceptions or errors, possibly including ClassCastException. |
| 1222 |
> |
* be polled or executed next. Conversely, this method may return |
| 1223 |
> |
* null even if a task exists but cannot be accessed without |
| 1224 |
> |
* contention with other threads. This method is designed |
| 1225 |
> |
* primarily to support extensions, and is unlikely to be useful |
| 1226 |
> |
* otherwise. |
| 1227 |
|
* |
| 1228 |
< |
* @return the next task, or null if none are available |
| 1228 |
> |
* @return the next task, or {@code null} if none are available |
| 1229 |
|
*/ |
| 1230 |
|
protected static ForkJoinTask<?> peekNextLocalTask() { |
| 1231 |
< |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
| 1232 |
< |
.peekTask(); |
| 1231 |
> |
Thread t; ForkJoinPool.WorkQueue q; |
| 1232 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
| 1233 |
> |
q = ((ForkJoinWorkerThread)t).workQueue; |
| 1234 |
> |
else |
| 1235 |
> |
q = ForkJoinPool.commonSubmitterQueue(); |
| 1236 |
> |
return (q == null) ? null : q.peek(); |
| 1237 |
|
} |
| 1238 |
|
|
| 1239 |
|
/** |
| 1240 |
|
* Unschedules and returns, without executing, the next task |
| 1241 |
< |
* queued by the current thread but not yet executed. This method |
| 1242 |
< |
* is designed primarily to support extensions, and is unlikely to |
| 1243 |
< |
* be useful otherwise. This method may be invoked only from |
| 1244 |
< |
* within ForkJoinTask computations (as may be determined using |
| 1010 |
< |
* method {@link #inForkJoinPool}). Attempts to invoke in other |
| 1011 |
< |
* contexts result in exceptions or errors, possibly including |
| 1012 |
< |
* ClassCastException. |
| 1241 |
> |
* queued by the current thread but not yet executed, if the |
| 1242 |
> |
* current thread is operating in a ForkJoinPool. This method is |
| 1243 |
> |
* designed primarily to support extensions, and is unlikely to be |
| 1244 |
> |
* useful otherwise. |
| 1245 |
|
* |
| 1246 |
< |
* @return the next task, or null if none are available |
| 1246 |
> |
* @return the next task, or {@code null} if none are available |
| 1247 |
|
*/ |
| 1248 |
|
protected static ForkJoinTask<?> pollNextLocalTask() { |
| 1249 |
< |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
| 1250 |
< |
.pollLocalTask(); |
| 1249 |
> |
Thread t; |
| 1250 |
> |
return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
| 1251 |
> |
((ForkJoinWorkerThread)t).workQueue.nextLocalTask() : |
| 1252 |
> |
null; |
| 1253 |
|
} |
| 1254 |
|
|
| 1255 |
|
/** |
| 1256 |
< |
* Unschedules and returns, without executing, the next task |
| 1256 |
> |
* If the current thread is operating in a ForkJoinPool, |
| 1257 |
> |
* unschedules and returns, without executing, the next task |
| 1258 |
|
* queued by the current thread but not yet executed, if one is |
| 1259 |
|
* available, or if not available, a task that was forked by some |
| 1260 |
|
* other thread, if available. Availability may be transient, so a |
| 1261 |
< |
* {@code null} result does not necessarily imply quiescence |
| 1262 |
< |
* of the pool this task is operating in. This method is designed |
| 1261 |
> |
* {@code null} result does not necessarily imply quiescence of |
| 1262 |
> |
* the pool this task is operating in. This method is designed |
| 1263 |
|
* primarily to support extensions, and is unlikely to be useful |
| 1264 |
< |
* otherwise. This method may be invoked only from within |
| 1030 |
< |
* ForkJoinTask computations (as may be determined using method |
| 1031 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
| 1032 |
< |
* result in exceptions or errors, possibly including |
| 1033 |
< |
* ClassCastException. |
| 1264 |
> |
* otherwise. |
| 1265 |
|
* |
| 1266 |
< |
* @return a task, or null if none are available |
| 1266 |
> |
* @return a task, or {@code null} if none are available |
| 1267 |
|
*/ |
| 1268 |
|
protected static ForkJoinTask<?> pollTask() { |
| 1269 |
< |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
| 1270 |
< |
.pollTask(); |
| 1269 |
> |
Thread t; ForkJoinWorkerThread wt; |
| 1270 |
> |
return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
| 1271 |
> |
(wt = (ForkJoinWorkerThread)t).pool.nextTaskFor(wt.workQueue) : |
| 1272 |
> |
null; |
| 1273 |
> |
} |
| 1274 |
> |
|
| 1275 |
> |
// tag operations |
| 1276 |
> |
|
| 1277 |
> |
/** |
| 1278 |
> |
* Returns the tag for this task. |
| 1279 |
> |
* |
| 1280 |
> |
* @return the tag for this task |
| 1281 |
> |
* @since 1.8 |
| 1282 |
> |
*/ |
| 1283 |
> |
public final short getForkJoinTaskTag() { |
| 1284 |
> |
return (short)status; |
| 1285 |
> |
} |
| 1286 |
> |
|
| 1287 |
> |
/** |
| 1288 |
> |
* Atomically sets the tag value for this task. |
| 1289 |
> |
* |
| 1290 |
> |
* @param tag the tag value |
| 1291 |
> |
* @return the previous value of the tag |
| 1292 |
> |
* @since 1.8 |
| 1293 |
> |
*/ |
| 1294 |
> |
public final short setForkJoinTaskTag(short tag) { |
| 1295 |
> |
for (int s;;) { |
| 1296 |
> |
if (U.compareAndSwapInt(this, STATUS, s = status, |
| 1297 |
> |
(s & ~SMASK) | (tag & SMASK))) |
| 1298 |
> |
return (short)s; |
| 1299 |
> |
} |
| 1300 |
> |
} |
| 1301 |
> |
|
| 1302 |
> |
/** |
| 1303 |
> |
* Atomically conditionally sets the tag value for this task. |
| 1304 |
> |
* Among other applications, tags can be used as visit markers |
| 1305 |
> |
* in tasks operating on graphs, as in methods that check: {@code |
| 1306 |
> |
* if (task.compareAndSetForkJoinTaskTag((short)0, (short)1))} |
| 1307 |
> |
* before processing, otherwise exiting because the node has |
| 1308 |
> |
* already been visited. |
| 1309 |
> |
* |
| 1310 |
> |
* @param e the expected tag value |
| 1311 |
> |
* @param tag the new tag value |
| 1312 |
> |
* @return true if successful; i.e., the current value was |
| 1313 |
> |
* equal to e and is now tag. |
| 1314 |
> |
* @since 1.8 |
| 1315 |
> |
*/ |
| 1316 |
> |
public final boolean compareAndSetForkJoinTaskTag(short e, short tag) { |
| 1317 |
> |
for (int s;;) { |
| 1318 |
> |
if ((short)(s = status) != e) |
| 1319 |
> |
return false; |
| 1320 |
> |
if (U.compareAndSwapInt(this, STATUS, s, |
| 1321 |
> |
(s & ~SMASK) | (tag & SMASK))) |
| 1322 |
> |
return true; |
| 1323 |
> |
} |
| 1324 |
> |
} |
| 1325 |
> |
|
| 1326 |
> |
/** |
| 1327 |
> |
* Adaptor for Runnables. This implements RunnableFuture |
| 1328 |
> |
* to be compliant with AbstractExecutorService constraints |
| 1329 |
> |
* when used in ForkJoinPool. |
| 1330 |
> |
*/ |
| 1331 |
> |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
| 1332 |
> |
implements RunnableFuture<T> { |
| 1333 |
> |
final Runnable runnable; |
| 1334 |
> |
T result; |
| 1335 |
> |
AdaptedRunnable(Runnable runnable, T result) { |
| 1336 |
> |
if (runnable == null) throw new NullPointerException(); |
| 1337 |
> |
this.runnable = runnable; |
| 1338 |
> |
this.result = result; // OK to set this even before completion |
| 1339 |
> |
} |
| 1340 |
> |
public final T getRawResult() { return result; } |
| 1341 |
> |
public final void setRawResult(T v) { result = v; } |
| 1342 |
> |
public final boolean exec() { runnable.run(); return true; } |
| 1343 |
> |
public final void run() { invoke(); } |
| 1344 |
> |
private static final long serialVersionUID = 5232453952276885070L; |
| 1345 |
> |
} |
| 1346 |
> |
|
| 1347 |
> |
/** |
| 1348 |
> |
* Adaptor for Runnables without results |
| 1349 |
> |
*/ |
| 1350 |
> |
static final class AdaptedRunnableAction extends ForkJoinTask<Void> |
| 1351 |
> |
implements RunnableFuture<Void> { |
| 1352 |
> |
final Runnable runnable; |
| 1353 |
> |
AdaptedRunnableAction(Runnable runnable) { |
| 1354 |
> |
if (runnable == null) throw new NullPointerException(); |
| 1355 |
> |
this.runnable = runnable; |
| 1356 |
> |
} |
| 1357 |
> |
public final Void getRawResult() { return null; } |
| 1358 |
> |
public final void setRawResult(Void v) { } |
| 1359 |
> |
public final boolean exec() { runnable.run(); return true; } |
| 1360 |
> |
public final void run() { invoke(); } |
| 1361 |
> |
private static final long serialVersionUID = 5232453952276885070L; |
| 1362 |
|
} |
| 1363 |
|
|
| 1364 |
< |
// adaptors |
| 1364 |
> |
/** |
| 1365 |
> |
* Adaptor for Callables |
| 1366 |
> |
*/ |
| 1367 |
> |
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
| 1368 |
> |
implements RunnableFuture<T> { |
| 1369 |
> |
final Callable<? extends T> callable; |
| 1370 |
> |
T result; |
| 1371 |
> |
AdaptedCallable(Callable<? extends T> callable) { |
| 1372 |
> |
if (callable == null) throw new NullPointerException(); |
| 1373 |
> |
this.callable = callable; |
| 1374 |
> |
} |
| 1375 |
> |
public final T getRawResult() { return result; } |
| 1376 |
> |
public final void setRawResult(T v) { result = v; } |
| 1377 |
> |
public final boolean exec() { |
| 1378 |
> |
try { |
| 1379 |
> |
result = callable.call(); |
| 1380 |
> |
return true; |
| 1381 |
> |
} catch (Error err) { |
| 1382 |
> |
throw err; |
| 1383 |
> |
} catch (RuntimeException rex) { |
| 1384 |
> |
throw rex; |
| 1385 |
> |
} catch (Exception ex) { |
| 1386 |
> |
throw new RuntimeException(ex); |
| 1387 |
> |
} |
| 1388 |
> |
} |
| 1389 |
> |
public final void run() { invoke(); } |
| 1390 |
> |
private static final long serialVersionUID = 2838392045355241008L; |
| 1391 |
> |
} |
| 1392 |
|
|
| 1393 |
|
/** |
| 1394 |
< |
* Returns a new ForkJoinTask that performs the <code>run</code> |
| 1395 |
< |
* method of the given Runnable as its action, and returns a null |
| 1396 |
< |
* result upon <code>join</code>. |
| 1394 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
| 1395 |
> |
* method of the given {@code Runnable} as its action, and returns |
| 1396 |
> |
* a null result upon {@link #join}. |
| 1397 |
|
* |
| 1398 |
|
* @param runnable the runnable action |
| 1399 |
|
* @return the task |
| 1400 |
|
*/ |
| 1401 |
< |
public static ForkJoinTask<Void> adapt(Runnable runnable) { |
| 1402 |
< |
return new ForkJoinPool.AdaptedRunnable<Void>(runnable, null); |
| 1401 |
> |
public static ForkJoinTask<?> adapt(Runnable runnable) { |
| 1402 |
> |
return new AdaptedRunnableAction(runnable); |
| 1403 |
|
} |
| 1404 |
|
|
| 1405 |
|
/** |
| 1406 |
< |
* Returns a new ForkJoinTask that performs the <code>run</code> |
| 1407 |
< |
* method of the given Runnable as its action, and returns the |
| 1408 |
< |
* given result upon <code>join</code>. |
| 1406 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
| 1407 |
> |
* method of the given {@code Runnable} as its action, and returns |
| 1408 |
> |
* the given result upon {@link #join}. |
| 1409 |
|
* |
| 1410 |
|
* @param runnable the runnable action |
| 1411 |
|
* @param result the result upon completion |
| 1412 |
|
* @return the task |
| 1413 |
|
*/ |
| 1414 |
|
public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) { |
| 1415 |
< |
return new ForkJoinPool.AdaptedRunnable<T>(runnable, result); |
| 1415 |
> |
return new AdaptedRunnable<T>(runnable, result); |
| 1416 |
|
} |
| 1417 |
|
|
| 1418 |
|
/** |
| 1419 |
< |
* Returns a new ForkJoinTask that performs the <code>call</code> |
| 1420 |
< |
* method of the given Callable as its action, and returns its |
| 1421 |
< |
* result upon <code>join</code>, translating any checked |
| 1422 |
< |
* exceptions encountered into <code>RuntimeException<code>. |
| 1419 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code call} |
| 1420 |
> |
* method of the given {@code Callable} as its action, and returns |
| 1421 |
> |
* its result upon {@link #join}, translating any checked exceptions |
| 1422 |
> |
* encountered into {@code RuntimeException}. |
| 1423 |
|
* |
| 1424 |
|
* @param callable the callable action |
| 1425 |
|
* @return the task |
| 1426 |
|
*/ |
| 1427 |
< |
public static <T> ForkJoinTask<T> adapt(Callable<T> callable) { |
| 1428 |
< |
return new ForkJoinPool.AdaptedCallable<T>(callable); |
| 1427 |
> |
public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) { |
| 1428 |
> |
return new AdaptedCallable<T>(callable); |
| 1429 |
|
} |
| 1430 |
|
|
| 1431 |
|
// Serialization support |
| 1433 |
|
private static final long serialVersionUID = -7721805057305804111L; |
| 1434 |
|
|
| 1435 |
|
/** |
| 1436 |
< |
* Save the state to a stream. |
| 1436 |
> |
* Saves this task to a stream (that is, serializes it). |
| 1437 |
|
* |
| 1438 |
|
* @serialData the current run status and the exception thrown |
| 1439 |
< |
* during execution, or null if none |
| 1091 |
< |
* @param s the stream |
| 1439 |
> |
* during execution, or {@code null} if none |
| 1440 |
|
*/ |
| 1441 |
|
private void writeObject(java.io.ObjectOutputStream s) |
| 1442 |
|
throws java.io.IOException { |
| 1445 |
|
} |
| 1446 |
|
|
| 1447 |
|
/** |
| 1448 |
< |
* Reconstitute the instance from a stream. |
| 1101 |
< |
* |
| 1102 |
< |
* @param s the stream |
| 1448 |
> |
* Reconstitutes this task from a stream (that is, deserializes it). |
| 1449 |
|
*/ |
| 1450 |
|
private void readObject(java.io.ObjectInputStream s) |
| 1451 |
|
throws java.io.IOException, ClassNotFoundException { |
| 1452 |
|
s.defaultReadObject(); |
| 1107 |
– |
status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts |
| 1108 |
– |
status |= EXTERNAL_SIGNAL; // conservatively set external signal |
| 1453 |
|
Object ex = s.readObject(); |
| 1454 |
|
if (ex != null) |
| 1455 |
< |
setDoneExceptionally((Throwable) ex); |
| 1455 |
> |
setExceptionalCompletion((Throwable)ex); |
| 1456 |
|
} |
| 1457 |
|
|
| 1458 |
< |
// Unsafe mechanics for jsr166y 3rd party package. |
| 1458 |
> |
// Unsafe mechanics |
| 1459 |
> |
private static final sun.misc.Unsafe U; |
| 1460 |
> |
private static final long STATUS; |
| 1461 |
> |
|
| 1462 |
> |
static { |
| 1463 |
> |
exceptionTableLock = new ReentrantLock(); |
| 1464 |
> |
exceptionTableRefQueue = new ReferenceQueue<Object>(); |
| 1465 |
> |
exceptionTable = new ExceptionNode[EXCEPTION_MAP_CAPACITY]; |
| 1466 |
> |
try { |
| 1467 |
> |
U = getUnsafe(); |
| 1468 |
> |
Class<?> k = ForkJoinTask.class; |
| 1469 |
> |
STATUS = U.objectFieldOffset |
| 1470 |
> |
(k.getDeclaredField("status")); |
| 1471 |
> |
} catch (Exception e) { |
| 1472 |
> |
throw new Error(e); |
| 1473 |
> |
} |
| 1474 |
> |
} |
| 1475 |
> |
|
| 1476 |
> |
/** |
| 1477 |
> |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
| 1478 |
> |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
| 1479 |
> |
* into a jdk. |
| 1480 |
> |
* |
| 1481 |
> |
* @return a sun.misc.Unsafe |
| 1482 |
> |
*/ |
| 1483 |
|
private static sun.misc.Unsafe getUnsafe() { |
| 1484 |
|
try { |
| 1485 |
|
return sun.misc.Unsafe.getUnsafe(); |
| 1486 |
|
} catch (SecurityException se) { |
| 1487 |
|
try { |
| 1488 |
|
return java.security.AccessController.doPrivileged |
| 1489 |
< |
(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
| 1489 |
> |
(new java.security |
| 1490 |
> |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
| 1491 |
|
public sun.misc.Unsafe run() throws Exception { |
| 1492 |
< |
return getUnsafeByReflection(); |
| 1492 |
> |
java.lang.reflect.Field f = sun.misc |
| 1493 |
> |
.Unsafe.class.getDeclaredField("theUnsafe"); |
| 1494 |
> |
f.setAccessible(true); |
| 1495 |
> |
return (sun.misc.Unsafe) f.get(null); |
| 1496 |
|
}}); |
| 1497 |
|
} catch (java.security.PrivilegedActionException e) { |
| 1498 |
|
throw new RuntimeException("Could not initialize intrinsics", |
| 1500 |
|
} |
| 1501 |
|
} |
| 1502 |
|
} |
| 1131 |
– |
|
| 1132 |
– |
private static sun.misc.Unsafe getUnsafeByReflection() |
| 1133 |
– |
throws NoSuchFieldException, IllegalAccessException { |
| 1134 |
– |
java.lang.reflect.Field f = |
| 1135 |
– |
sun.misc.Unsafe.class.getDeclaredField("theUnsafe"); |
| 1136 |
– |
f.setAccessible(true); |
| 1137 |
– |
return (sun.misc.Unsafe) f.get(null); |
| 1138 |
– |
} |
| 1139 |
– |
|
| 1140 |
– |
private static long fieldOffset(String fieldName, Class<?> klazz) { |
| 1141 |
– |
try { |
| 1142 |
– |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(fieldName)); |
| 1143 |
– |
} catch (NoSuchFieldException e) { |
| 1144 |
– |
// Convert Exception to Error |
| 1145 |
– |
NoSuchFieldError error = new NoSuchFieldError(fieldName); |
| 1146 |
– |
error.initCause(e); |
| 1147 |
– |
throw error; |
| 1148 |
– |
} |
| 1149 |
– |
} |
| 1150 |
– |
|
| 1151 |
– |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
| 1152 |
– |
private static final long statusOffset = |
| 1153 |
– |
fieldOffset("status", ForkJoinTask.class); |
| 1154 |
– |
|
| 1503 |
|
} |
