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*/ |
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package jsr166y; |
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+ |
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import java.io.Serializable; |
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import java.util.*; |
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import java.util.concurrent.*; |
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< |
import java.util.concurrent.atomic.*; |
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import sun.misc.Unsafe; |
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import java.lang.reflect.*; |
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import java.util.Collection; |
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import java.util.Collections; |
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import java.util.List; |
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import java.util.RandomAccess; |
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import java.util.Map; |
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import java.util.WeakHashMap; |
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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.Executor; |
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import java.util.concurrent.ExecutorService; |
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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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|
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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 |
37 |
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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 |
40 |
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* of other methods that can come into play in advanced usages, as |
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* well as extension mechanics that allow support of new forms of |
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* fork/join processing. |
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* <p>A "main" {@code ForkJoinTask} begins execution when submitted |
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* to a {@link ForkJoinPool}. Once started, it will usually in turn |
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* start other subtasks. As indicated by the name of this class, |
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* many programs using {@code ForkJoinTask} employ only methods |
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* {@link #fork} and {@link #join}, or derivatives such as {@link |
39 |
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* #invokeAll(ForkJoinTask...) invokeAll}. However, this class also |
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* provides a number of other methods that can come into play in |
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* advanced usages, as well as extension mechanics that allow |
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* support of new forms of fork/join processing. |
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* |
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* <p>A 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. |
44 |
> |
* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}. |
45 |
> |
* The efficiency of {@code ForkJoinTask}s stems from a set of |
46 |
> |
* restrictions (that are only partially statically enforceable) |
47 |
> |
* reflecting their intended use as computational tasks calculating |
48 |
> |
* pure functions or operating on purely isolated objects. The |
49 |
> |
* primary 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 |
52 |
> |
* avoid {@code synchronized} methods or blocks, and should minimize |
53 |
> |
* other blocking synchronization apart from joining other tasks or |
54 |
> |
* using synchronizers such as Phasers that are advertised to |
55 |
> |
* cooperate with fork/join scheduling. Tasks should also not perform |
56 |
> |
* blocking IO, and should ideally access variables that are |
57 |
> |
* completely independent of those accessed by other running |
58 |
> |
* tasks. Minor breaches of these restrictions, for example using |
59 |
> |
* shared output streams, may be tolerable in practice, but frequent |
60 |
> |
* use may result in poor performance, and the potential to |
61 |
> |
* indefinitely stall if the number of threads not waiting for IO or |
62 |
> |
* other external synchronization becomes exhausted. This usage |
63 |
> |
* restriction is in part enforced by not permitting checked |
64 |
> |
* exceptions such as {@code IOExceptions} to be thrown. However, |
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* computations may still encounter unchecked exceptions, that are |
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* rethrown to callers attempting to join them. These exceptions may |
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* additionally include {@link RejectedExecutionException} stemming |
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* from internal resource exhaustion, such as failure to allocate |
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* internal task queues. |
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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>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. |
98 |
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* Instead, you subclass one of the abstract classes that support a |
99 |
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* particular style of fork/join processing. Normally, a concrete |
99 |
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* particular style of fork/join processing, typically {@link |
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* RecursiveAction} for computations that do not return results, or |
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* {@link RecursiveTask} for those that do. 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} |
104 |
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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 |
106 |
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* instances of different task subclasses to call each others |
106 |
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* instances of different task subclasses to call each other's |
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* methods), some of them may only be called from within other |
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* ForkJoinTasks. Attempts to invoke them in other contexts result in |
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* exceptions or errors possibly including ClassCastException. |
108 |
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* ForkJoinTasks (as may be determined using method {@link |
109 |
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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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* {@code ClassCastException}. |
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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 |
115 |
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* underlying lightweight task scheduling framework. Developers |
116 |
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* creating new basic styles of fork/join processing should minimally |
117 |
> |
* implement {@code protected} methods {@link #exec}, {@link |
118 |
> |
* #setRawResult}, and {@link #getRawResult}, while also introducing |
119 |
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* an abstract computational method that can be implemented in its |
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* subclasses, possibly relying on other {@code protected} methods |
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* provided by this class. |
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* |
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* <p>ForkJoinTasks should perform relatively small amounts of |
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* computations, othewise splitting into smaller tasks. As a very |
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* rough rule of thumb, a task should perform more than 100 and less |
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* than 10000 basic computational steps. If tasks are too big, then |
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* parellelism cannot improve throughput. If too small, then memory |
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* and internal task maintenance overhead may overwhelm processing. |
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* computation. Large tasks should be split into smaller subtasks, |
125 |
> |
* usually via recursive decomposition. As a very rough rule of thumb, |
126 |
> |
* a task should perform more than 100 and less than 10000 basic |
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> |
* computational steps. If tasks are too big, then parallelism cannot |
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* improve throughput. If too small, then memory and internal task |
129 |
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* maintenance overhead may overwhelm processing. |
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* |
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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 |
137 |
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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 |
139 |
< |
* not during execution. Serialization is not relied on during |
140 |
< |
* execution itself. |
136 |
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* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
137 |
> |
* used in extensions such as remote execution frameworks. It is |
138 |
> |
* sensible to serialize tasks only before or after, but not during, |
139 |
> |
* 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 { |
145 |
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|
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/** |
147 |
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* Run control status bits packed into a single int to minimize |
148 |
< |
* footprint and to ensure atomicity (via CAS). Status is |
149 |
< |
* initially zero, and takes on nonnegative values until |
150 |
< |
* completed, upon which status holds COMPLETED. CANCELLED, or |
151 |
< |
* EXCEPTIONAL, which use the top 3 bits. Tasks undergoing |
152 |
< |
* blocking waits by other threads have SIGNAL_MASK bits set -- |
153 |
< |
* bit 15 for external (nonFJ) waits, and the rest a count of |
154 |
< |
* waiting FJ threads. (This representation relies on |
155 |
< |
* ForkJoinPool max thread limits). Completion of a stolen task |
156 |
< |
* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even |
157 |
< |
* though suboptimal for some purposes, we use basic builtin |
158 |
< |
* wait/notify to take advantage of "monitor inflation" in JVMs |
159 |
< |
* that we would otherwise need to emulate to avoid adding further |
160 |
< |
* per-task bookkeeping overhead. Note that bits 16-28 are |
161 |
< |
* currently unused. Also value 0x80000000 is available as spare |
162 |
< |
* completion value. |
163 |
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*/ |
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volatile int status; // accessed directy by pool and workers |
165 |
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|
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static final int COMPLETION_MASK = 0xe0000000; |
167 |
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static final int NORMAL = 0xe0000000; // == mask |
168 |
< |
static final int CANCELLED = 0xc0000000; |
169 |
< |
static final int EXCEPTIONAL = 0xa0000000; |
170 |
< |
static final int SIGNAL_MASK = 0x0000ffff; |
171 |
< |
static final int INTERNAL_SIGNAL_MASK = 0x00007fff; |
172 |
< |
static final int EXTERNAL_SIGNAL = 0x00008000; // top bit of low word |
146 |
> |
/* |
147 |
> |
* See the internal documentation of class ForkJoinPool for a |
148 |
> |
* general implementation overview. ForkJoinTasks are mainly |
149 |
> |
* responsible for maintaining their "status" field amidst relays |
150 |
> |
* to methods in ForkJoinWorkerThread and ForkJoinPool. The |
151 |
> |
* methods of this class are more-or-less layered into (1) basic |
152 |
> |
* status maintenance (2) execution and awaiting completion (3) |
153 |
> |
* user-level methods that additionally report results. This is |
154 |
> |
* sometimes hard to see because this file orders exported methods |
155 |
> |
* in a way that flows well in javadocs. In particular, most |
156 |
> |
* join mechanics are in method quietlyJoin, below. |
157 |
> |
*/ |
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> |
|
159 |
> |
/* |
160 |
> |
* The status field holds run control status bits packed into a |
161 |
> |
* single int to minimize footprint and to ensure atomicity (via |
162 |
> |
* CAS). Status is initially zero, and takes on nonnegative |
163 |
> |
* values until completed, upon which status holds value |
164 |
> |
* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking |
165 |
> |
* waits by other threads have the SIGNAL bit set. Completion of |
166 |
> |
* a stolen task with SIGNAL set awakens any waiters via |
167 |
> |
* notifyAll. Even though suboptimal for some purposes, we use |
168 |
> |
* basic builtin wait/notify to take advantage of "monitor |
169 |
> |
* inflation" in JVMs that we would otherwise need to emulate to |
170 |
> |
* avoid adding further per-task bookkeeping overhead. We want |
171 |
> |
* these monitors to be "fat", i.e., not use biasing or thin-lock |
172 |
> |
* techniques, so use some odd coding idioms that tend to avoid |
173 |
> |
* them. |
174 |
> |
*/ |
175 |
> |
|
176 |
> |
/** The run status of this task */ |
177 |
> |
volatile int status; // accessed directly by pool and workers |
178 |
> |
|
179 |
> |
private static final int NORMAL = -1; |
180 |
> |
private static final int CANCELLED = -2; |
181 |
> |
private static final int EXCEPTIONAL = -3; |
182 |
> |
private static final int SIGNAL = 1; |
183 |
|
|
184 |
|
/** |
185 |
|
* Table of exceptions thrown by tasks, to enable reporting by |
186 |
|
* callers. Because exceptions are rare, we don't directly keep |
187 |
< |
* them with task objects, but instead us a weak ref table. Note |
187 |
> |
* them with task objects, but instead use a weak ref table. Note |
188 |
|
* that cancellation exceptions don't appear in the table, but are |
189 |
|
* instead recorded as status values. |
190 |
< |
* Todo: Use ConcurrentReferenceHashMap |
190 |
> |
* TODO: Use ConcurrentReferenceHashMap |
191 |
|
*/ |
192 |
|
static final Map<ForkJoinTask<?>, Throwable> exceptionMap = |
193 |
|
Collections.synchronizedMap |
194 |
|
(new WeakHashMap<ForkJoinTask<?>, Throwable>()); |
195 |
|
|
196 |
< |
// within-package utilities |
196 |
> |
// Maintaining completion status |
197 |
|
|
198 |
|
/** |
199 |
< |
* Get current worker thread, or null if not a worker thread |
200 |
< |
*/ |
201 |
< |
static ForkJoinWorkerThread getWorker() { |
159 |
< |
Thread t = Thread.currentThread(); |
160 |
< |
return ((t instanceof ForkJoinWorkerThread)? |
161 |
< |
(ForkJoinWorkerThread)t : null); |
162 |
< |
} |
163 |
< |
|
164 |
< |
final boolean casStatus(int cmp, int val) { |
165 |
< |
return _unsafe.compareAndSwapInt(this, statusOffset, cmp, val); |
166 |
< |
} |
167 |
< |
|
168 |
< |
/** |
169 |
< |
* Workaround for not being able to rethrow unchecked exceptions. |
170 |
< |
*/ |
171 |
< |
static void rethrowException(Throwable ex) { |
172 |
< |
if (ex != null) |
173 |
< |
_unsafe.throwException(ex); |
174 |
< |
} |
175 |
< |
|
176 |
< |
// Setting completion status |
177 |
< |
|
178 |
< |
/** |
179 |
< |
* Mark completion and wake up threads waiting to join this task. |
199 |
> |
* Marks completion and wakes up threads waiting to join this task, |
200 |
> |
* also clearing signal request bits. |
201 |
> |
* |
202 |
|
* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL |
203 |
|
*/ |
204 |
< |
final void setCompletion(int completion) { |
205 |
< |
ForkJoinPool pool = getPool(); |
206 |
< |
if (pool != null) { |
207 |
< |
int s; // Clear signal bits while setting completion status |
208 |
< |
do;while ((s = status) >= 0 && !casStatus(s, completion)); |
209 |
< |
|
210 |
< |
if ((s & SIGNAL_MASK) != 0) { |
189 |
< |
if ((s &= INTERNAL_SIGNAL_MASK) != 0) |
190 |
< |
pool.updateRunningCount(s); |
191 |
< |
synchronized(this) { notifyAll(); } |
204 |
> |
private void setCompletion(int completion) { |
205 |
> |
int s; |
206 |
> |
while ((s = status) >= 0) { |
207 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) { |
208 |
> |
if (s != 0) |
209 |
> |
synchronized (this) { notifyAll(); } |
210 |
> |
break; |
211 |
|
} |
212 |
|
} |
194 |
– |
else |
195 |
– |
externallySetCompletion(completion); |
196 |
– |
} |
197 |
– |
|
198 |
– |
/** |
199 |
– |
* Version of setCompletion for non-FJ threads. Leaves signal |
200 |
– |
* bits for unblocked threads to adjust, and always notifies. |
201 |
– |
*/ |
202 |
– |
private void externallySetCompletion(int completion) { |
203 |
– |
int s; |
204 |
– |
do;while ((s = status) >= 0 && |
205 |
– |
!casStatus(s, (s & SIGNAL_MASK) | completion)); |
206 |
– |
synchronized(this) { notifyAll(); } |
213 |
|
} |
214 |
|
|
215 |
|
/** |
216 |
< |
* Sets status to indicate normal completion |
217 |
< |
*/ |
218 |
< |
final void setNormalCompletion() { |
213 |
< |
// Try typical fast case -- single CAS, no signal, not already done. |
214 |
< |
// Manually expand casStatus to improve chances of inlining it |
215 |
< |
if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL)) |
216 |
< |
setCompletion(NORMAL); |
217 |
< |
} |
218 |
< |
|
219 |
< |
// internal waiting and notification |
220 |
< |
|
221 |
< |
/** |
222 |
< |
* Performs the actual monitor wait for awaitDone |
216 |
> |
* Records exception and sets exceptional completion. |
217 |
> |
* |
218 |
> |
* @return status on exit |
219 |
|
*/ |
220 |
< |
private void doAwaitDone() { |
221 |
< |
// Minimize lock bias and in/de-flation effects by maximizing |
222 |
< |
// chances of waiting inside sync |
227 |
< |
try { |
228 |
< |
while (status >= 0) |
229 |
< |
synchronized(this) { if (status >= 0) wait(); } |
230 |
< |
} catch (InterruptedException ie) { |
231 |
< |
onInterruptedWait(); |
232 |
< |
} |
220 |
> |
private void setExceptionalCompletion(Throwable rex) { |
221 |
> |
exceptionMap.put(this, rex); |
222 |
> |
setCompletion(EXCEPTIONAL); |
223 |
|
} |
224 |
|
|
225 |
|
/** |
226 |
< |
* Performs the actual monitor wait for awaitDone |
226 |
> |
* Blocks a worker thread until completion. Called only by |
227 |
> |
* pool. Currently unused -- pool-based waits use timeout |
228 |
> |
* version below. |
229 |
|
*/ |
230 |
< |
private void doAwaitDone(long startTime, long nanos) { |
231 |
< |
synchronized(this) { |
230 |
> |
final void internalAwaitDone() { |
231 |
> |
int s; // the odd construction reduces lock bias effects |
232 |
> |
while ((s = status) >= 0) { |
233 |
|
try { |
234 |
< |
while (status >= 0) { |
235 |
< |
long nt = nanos - System.nanoTime() - startTime; |
236 |
< |
if (nt <= 0) |
244 |
< |
break; |
245 |
< |
wait(nt / 1000000, (int)(nt % 1000000)); |
234 |
> |
synchronized (this) { |
235 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL)) |
236 |
> |
wait(); |
237 |
|
} |
238 |
|
} catch (InterruptedException ie) { |
239 |
< |
onInterruptedWait(); |
239 |
> |
cancelIfTerminating(); |
240 |
|
} |
241 |
|
} |
242 |
|
} |
243 |
|
|
253 |
– |
// Awaiting completion |
254 |
– |
|
244 |
|
/** |
245 |
< |
* Sets status to indicate there is joiner, then waits for join, |
246 |
< |
* surrounded with pool notifications. |
247 |
< |
* @return status upon exit |
248 |
< |
*/ |
260 |
< |
private int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) { |
261 |
< |
ForkJoinPool pool = w == null? null : w.pool; |
262 |
< |
int s; |
263 |
< |
while ((s = status) >= 0) { |
264 |
< |
if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) { |
265 |
< |
if (pool == null || !pool.preJoin(this, maintainParallelism)) |
266 |
< |
doAwaitDone(); |
267 |
< |
if (((s = status) & INTERNAL_SIGNAL_MASK) != 0) |
268 |
< |
adjustPoolCountsOnUnblock(pool); |
269 |
< |
break; |
270 |
< |
} |
271 |
< |
} |
272 |
< |
return s; |
273 |
< |
} |
274 |
< |
|
275 |
< |
/** |
276 |
< |
* Timed version of awaitDone |
277 |
< |
* @return status upon exit |
245 |
> |
* Blocks a worker thread until completed or timed out. Called |
246 |
> |
* only by pool. |
247 |
> |
* |
248 |
> |
* @return status on exit |
249 |
|
*/ |
250 |
< |
private int awaitDone(ForkJoinWorkerThread w, long nanos) { |
280 |
< |
ForkJoinPool pool = w == null? null : w.pool; |
250 |
> |
final int internalAwaitDone(long millis, int nanos) { |
251 |
|
int s; |
252 |
< |
while ((s = status) >= 0) { |
253 |
< |
if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) { |
254 |
< |
long startTime = System.nanoTime(); |
255 |
< |
if (pool == null || !pool.preJoin(this, false)) |
256 |
< |
doAwaitDone(startTime, nanos); |
287 |
< |
if ((s = status) >= 0) { |
288 |
< |
adjustPoolCountsOnCancelledWait(pool); |
289 |
< |
s = status; |
252 |
> |
if ((s = status) >= 0) { |
253 |
> |
try { |
254 |
> |
synchronized (this) { |
255 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL)) |
256 |
> |
wait(millis, nanos); |
257 |
|
} |
258 |
< |
if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0) |
259 |
< |
adjustPoolCountsOnUnblock(pool); |
293 |
< |
break; |
258 |
> |
} catch (InterruptedException ie) { |
259 |
> |
cancelIfTerminating(); |
260 |
|
} |
261 |
+ |
s = status; |
262 |
|
} |
263 |
|
return s; |
264 |
|
} |
265 |
|
|
266 |
|
/** |
267 |
< |
* Notify pool that thread is unblocked. Called by signalled |
301 |
< |
* threads when woken by non-FJ threads (which is atypical). |
267 |
> |
* Blocks a non-worker-thread until completion. |
268 |
|
*/ |
269 |
< |
private void adjustPoolCountsOnUnblock(ForkJoinPool pool) { |
269 |
> |
private void externalAwaitDone() { |
270 |
|
int s; |
271 |
< |
do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK)); |
272 |
< |
if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0) |
273 |
< |
pool.updateRunningCount(s); |
274 |
< |
} |
275 |
< |
|
276 |
< |
/** |
277 |
< |
* Notify pool to adjust counts on cancelled or timed out wait |
278 |
< |
*/ |
279 |
< |
private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) { |
280 |
< |
if (pool != null) { |
281 |
< |
int s; |
282 |
< |
while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) { |
283 |
< |
if (casStatus(s, s - 1)) { |
318 |
< |
pool.updateRunningCount(1); |
271 |
> |
while ((s = status) >= 0) { |
272 |
> |
synchronized (this) { |
273 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) { |
274 |
> |
boolean interrupted = false; |
275 |
> |
while (status >= 0) { |
276 |
> |
try { |
277 |
> |
wait(); |
278 |
> |
} catch (InterruptedException ie) { |
279 |
> |
interrupted = true; |
280 |
> |
} |
281 |
> |
} |
282 |
> |
if (interrupted) |
283 |
> |
Thread.currentThread().interrupt(); |
284 |
|
break; |
285 |
|
} |
286 |
|
} |
288 |
|
} |
289 |
|
|
290 |
|
/** |
291 |
< |
* Handle interruptions during waits. |
292 |
< |
*/ |
293 |
< |
private void onInterruptedWait() { |
329 |
< |
ForkJoinWorkerThread w = getWorker(); |
330 |
< |
if (w == null) |
331 |
< |
Thread.currentThread().interrupt(); // re-interrupt |
332 |
< |
else if (w.isTerminating()) |
333 |
< |
cancelIgnoringExceptions(); |
334 |
< |
// else if FJworker, ignore interrupt |
335 |
< |
} |
336 |
< |
|
337 |
< |
// Recording and reporting exceptions |
338 |
< |
|
339 |
< |
private void setDoneExceptionally(Throwable rex) { |
340 |
< |
exceptionMap.put(this, rex); |
341 |
< |
setCompletion(EXCEPTIONAL); |
342 |
< |
} |
343 |
< |
|
344 |
< |
/** |
345 |
< |
* Throws the exception associated with status s; |
346 |
< |
* @throws the exception |
347 |
< |
*/ |
348 |
< |
private void reportException(int s) { |
349 |
< |
if ((s &= COMPLETION_MASK) < NORMAL) { |
350 |
< |
if (s == CANCELLED) |
351 |
< |
throw new CancellationException(); |
352 |
< |
else |
353 |
< |
rethrowException(exceptionMap.get(this)); |
354 |
< |
} |
355 |
< |
} |
356 |
< |
|
357 |
< |
/** |
358 |
< |
* Returns result or throws exception using j.u.c.Future conventions |
359 |
< |
* Only call when isDone known to be true. |
360 |
< |
*/ |
361 |
< |
private V reportFutureResult() |
362 |
< |
throws ExecutionException, InterruptedException { |
363 |
< |
int s = status & COMPLETION_MASK; |
364 |
< |
if (s < NORMAL) { |
365 |
< |
Throwable ex; |
366 |
< |
if (s == CANCELLED) |
367 |
< |
throw new CancellationException(); |
368 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
369 |
< |
throw new ExecutionException(ex); |
370 |
< |
if (Thread.interrupted()) |
371 |
< |
throw new InterruptedException(); |
372 |
< |
} |
373 |
< |
return getRawResult(); |
374 |
< |
} |
375 |
< |
|
376 |
< |
/** |
377 |
< |
* Returns result or throws exception using j.u.c.Future conventions |
378 |
< |
* with timeouts |
379 |
< |
*/ |
380 |
< |
private V reportTimedFutureResult() |
381 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
382 |
< |
Throwable ex; |
383 |
< |
int s = status & COMPLETION_MASK; |
384 |
< |
if (s == NORMAL) |
385 |
< |
return getRawResult(); |
386 |
< |
if (s == CANCELLED) |
387 |
< |
throw new CancellationException(); |
388 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
389 |
< |
throw new ExecutionException(ex); |
390 |
< |
if (Thread.interrupted()) |
391 |
< |
throw new InterruptedException(); |
392 |
< |
throw new TimeoutException(); |
393 |
< |
} |
394 |
< |
|
395 |
< |
// internal execution methods |
396 |
< |
|
397 |
< |
/** |
398 |
< |
* Calls exec, recording completion, and rethrowing exception if |
399 |
< |
* encountered. Caller should normally check status before calling |
400 |
< |
* @return true if completed normally |
401 |
< |
*/ |
402 |
< |
private boolean tryExec() { |
403 |
< |
try { // try block must contain only call to exec |
404 |
< |
if (!exec()) |
405 |
< |
return false; |
406 |
< |
} catch (Throwable rex) { |
407 |
< |
setDoneExceptionally(rex); |
408 |
< |
rethrowException(rex); |
409 |
< |
return false; // not reached |
410 |
< |
} |
411 |
< |
setNormalCompletion(); |
412 |
< |
return true; |
413 |
< |
} |
414 |
< |
|
415 |
< |
/** |
416 |
< |
* Main execution method used by worker threads. Invokes |
417 |
< |
* base computation unless already complete |
291 |
> |
* Unless done, calls exec and records status if completed, but |
292 |
> |
* doesn't wait for completion otherwise. Primary execution method |
293 |
> |
* for ForkJoinWorkerThread. |
294 |
|
*/ |
295 |
|
final void quietlyExec() { |
420 |
– |
if (status >= 0) { |
421 |
– |
try { |
422 |
– |
if (!exec()) |
423 |
– |
return; |
424 |
– |
} catch(Throwable rex) { |
425 |
– |
setDoneExceptionally(rex); |
426 |
– |
return; |
427 |
– |
} |
428 |
– |
setNormalCompletion(); |
429 |
– |
} |
430 |
– |
} |
431 |
– |
|
432 |
– |
/** |
433 |
– |
* Calls exec, recording but not rethrowing exception |
434 |
– |
* Caller should normally check status before calling |
435 |
– |
* @return true if completed normally |
436 |
– |
*/ |
437 |
– |
private boolean tryQuietlyInvoke() { |
296 |
|
try { |
297 |
< |
if (!exec()) |
298 |
< |
return false; |
297 |
> |
if (status < 0 || !exec()) |
298 |
> |
return; |
299 |
|
} catch (Throwable rex) { |
300 |
< |
setDoneExceptionally(rex); |
301 |
< |
return false; |
444 |
< |
} |
445 |
< |
setNormalCompletion(); |
446 |
< |
return true; |
447 |
< |
} |
448 |
< |
|
449 |
< |
/** |
450 |
< |
* Cancel, ignoring any exceptions it throws |
451 |
< |
*/ |
452 |
< |
final void cancelIgnoringExceptions() { |
453 |
< |
try { |
454 |
< |
cancel(false); |
455 |
< |
} catch(Throwable ignore) { |
300 |
> |
setExceptionalCompletion(rex); |
301 |
> |
return; |
302 |
|
} |
303 |
< |
} |
458 |
< |
|
459 |
< |
/** |
460 |
< |
* Main implementation of helpJoin |
461 |
< |
*/ |
462 |
< |
private int busyJoin(ForkJoinWorkerThread w) { |
463 |
< |
int s; |
464 |
< |
ForkJoinTask<?> t; |
465 |
< |
while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null) |
466 |
< |
t.quietlyExec(); |
467 |
< |
return (s >= 0)? awaitDone(w, false) : s; // block if no work |
303 |
> |
setCompletion(NORMAL); // must be outside try block |
304 |
|
} |
305 |
|
|
306 |
|
// public methods |
308 |
|
/** |
309 |
|
* Arranges to asynchronously execute this task. While it is not |
310 |
|
* necessarily enforced, it is a usage error to fork a task more |
311 |
< |
* than once unless it has completed and been reinitialized. This |
312 |
< |
* method may be invoked only from within ForkJoinTask |
313 |
< |
* computations. Attempts to invoke in other contexts result in |
314 |
< |
* exceptions or errors possibly including ClassCastException. |
311 |
> |
* than once unless it has completed and been reinitialized. |
312 |
> |
* Subsequent modifications to the state of this task or any data |
313 |
> |
* it operates on are not necessarily consistently observable by |
314 |
> |
* any thread other than the one executing it unless preceded by a |
315 |
> |
* call to {@link #join} or related methods, or a call to {@link |
316 |
> |
* #isDone} returning {@code true}. |
317 |
> |
* |
318 |
> |
* <p>This method may be invoked only from within {@code |
319 |
> |
* ForkJoinTask} computations (as may be determined using method |
320 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
321 |
> |
* result in exceptions or errors, possibly including {@code |
322 |
> |
* ClassCastException}. |
323 |
> |
* |
324 |
> |
* @return {@code this}, to simplify usage |
325 |
|
*/ |
326 |
< |
public final void fork() { |
327 |
< |
((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this); |
326 |
> |
public final ForkJoinTask<V> fork() { |
327 |
> |
((ForkJoinWorkerThread) Thread.currentThread()) |
328 |
> |
.pushTask(this); |
329 |
> |
return this; |
330 |
|
} |
331 |
|
|
332 |
|
/** |
333 |
< |
* Returns the result of the computation when it is ready. |
334 |
< |
* This method differs from {@code get} in that abnormal |
335 |
< |
* completion results in RuntimeExceptions or Errors, not |
336 |
< |
* ExecutionExceptions. |
333 |
> |
* Returns the result of the computation when it {@link #isDone is done}. |
334 |
> |
* This method differs from {@link #get()} in that |
335 |
> |
* abnormal completion results in {@code RuntimeException} or |
336 |
> |
* {@code Error}, not {@code ExecutionException}. |
337 |
|
* |
338 |
|
* @return the computed result |
339 |
|
*/ |
340 |
|
public final V join() { |
341 |
< |
ForkJoinWorkerThread w = getWorker(); |
342 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryExec()) |
343 |
< |
reportException(awaitDone(w, true)); |
341 |
> |
quietlyJoin(); |
342 |
> |
Throwable ex; |
343 |
> |
if (status < NORMAL && (ex = getException()) != null) |
344 |
> |
UNSAFE.throwException(ex); |
345 |
|
return getRawResult(); |
346 |
|
} |
347 |
|
|
348 |
|
/** |
349 |
|
* Commences performing this task, awaits its completion if |
350 |
< |
* necessary, and return its result. |
351 |
< |
* @throws Throwable (a RuntimeException, Error, or unchecked |
352 |
< |
* exception) if the underlying computation did so. |
350 |
> |
* necessary, and returns its result, or throws an (unchecked) |
351 |
> |
* {@code RuntimeException} or {@code Error} if the underlying |
352 |
> |
* computation did so. |
353 |
> |
* |
354 |
|
* @return the computed result |
355 |
|
*/ |
356 |
|
public final V invoke() { |
357 |
< |
if (status >= 0 && tryExec()) |
358 |
< |
return getRawResult(); |
359 |
< |
else |
360 |
< |
return join(); |
357 |
> |
quietlyInvoke(); |
358 |
> |
Throwable ex; |
359 |
> |
if (status < NORMAL && (ex = getException()) != null) |
360 |
> |
UNSAFE.throwException(ex); |
361 |
> |
return getRawResult(); |
362 |
|
} |
363 |
|
|
364 |
|
/** |
365 |
< |
* Forks both tasks, returning when {@code isDone} holds for |
366 |
< |
* both of them or an exception is encountered. This method may be |
367 |
< |
* invoked only from within ForkJoinTask computations. Attempts to |
368 |
< |
* invoke in other contexts result in exceptions or errors |
369 |
< |
* possibly including ClassCastException. |
370 |
< |
* @param t1 one task |
371 |
< |
* @param t2 the other task |
372 |
< |
* @throws NullPointerException if t1 or t2 are null |
373 |
< |
* @throws RuntimeException or Error if either task did so. |
365 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
366 |
> |
* each task or an (unchecked) exception is encountered, in which |
367 |
> |
* case the exception is rethrown. If more than one task |
368 |
> |
* encounters an exception, then this method throws any one of |
369 |
> |
* these exceptions. If any task encounters an exception, the |
370 |
> |
* other may be cancelled. However, the execution status of |
371 |
> |
* individual tasks is not guaranteed upon exceptional return. The |
372 |
> |
* status of each task may be obtained using {@link |
373 |
> |
* #getException()} and related methods to check if they have been |
374 |
> |
* cancelled, completed normally or exceptionally, or left |
375 |
> |
* unprocessed. |
376 |
> |
* |
377 |
> |
* <p>This method may be invoked only from within {@code |
378 |
> |
* ForkJoinTask} computations (as may be determined using method |
379 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
380 |
> |
* result in exceptions or errors, possibly including {@code |
381 |
> |
* ClassCastException}. |
382 |
> |
* |
383 |
> |
* @param t1 the first task |
384 |
> |
* @param t2 the second task |
385 |
> |
* @throws NullPointerException if any task is null |
386 |
|
*/ |
387 |
< |
public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) { |
387 |
> |
public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) { |
388 |
|
t2.fork(); |
389 |
|
t1.invoke(); |
390 |
|
t2.join(); |
391 |
|
} |
392 |
|
|
393 |
|
/** |
394 |
< |
* Forks the given tasks, returning when {@code isDone} holds |
395 |
< |
* for all of them. If any task encounters an exception, others |
396 |
< |
* may be cancelled. This method may be invoked only from within |
397 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
398 |
< |
* result in exceptions or errors possibly including ClassCastException. |
399 |
< |
* @param tasks the array of tasks |
400 |
< |
* @throws NullPointerException if tasks or any element are null. |
401 |
< |
* @throws RuntimeException or Error if any task did so. |
394 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
395 |
> |
* each task or an (unchecked) exception is encountered, in which |
396 |
> |
* case the exception is rethrown. If more than one task |
397 |
> |
* encounters an exception, then this method throws any one of |
398 |
> |
* these exceptions. If any task encounters an exception, others |
399 |
> |
* may be cancelled. However, the execution status of individual |
400 |
> |
* tasks is not guaranteed upon exceptional return. The status of |
401 |
> |
* each task may be obtained using {@link #getException()} and |
402 |
> |
* related methods to check if they have been cancelled, completed |
403 |
> |
* normally or exceptionally, or left unprocessed. |
404 |
> |
* |
405 |
> |
* <p>This method may be invoked only from within {@code |
406 |
> |
* ForkJoinTask} computations (as may be determined using method |
407 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
408 |
> |
* result in exceptions or errors, possibly including {@code |
409 |
> |
* ClassCastException}. |
410 |
> |
* |
411 |
> |
* @param tasks the tasks |
412 |
> |
* @throws NullPointerException if any task is null |
413 |
|
*/ |
414 |
|
public static void invokeAll(ForkJoinTask<?>... tasks) { |
415 |
|
Throwable ex = null; |
424 |
|
t.fork(); |
425 |
|
else { |
426 |
|
t.quietlyInvoke(); |
427 |
< |
if (ex == null) |
427 |
> |
if (ex == null && t.status < NORMAL) |
428 |
|
ex = t.getException(); |
429 |
|
} |
430 |
|
} |
435 |
|
t.cancel(false); |
436 |
|
else { |
437 |
|
t.quietlyJoin(); |
438 |
< |
if (ex == null) |
438 |
> |
if (ex == null && t.status < NORMAL) |
439 |
|
ex = t.getException(); |
440 |
|
} |
441 |
|
} |
442 |
|
} |
443 |
|
if (ex != null) |
444 |
< |
rethrowException(ex); |
444 |
> |
UNSAFE.throwException(ex); |
445 |
|
} |
446 |
|
|
447 |
|
/** |
448 |
< |
* Forks all tasks in the collection, returning when |
449 |
< |
* {@code isDone} holds for all of them. If any task |
450 |
< |
* encounters an exception, others may be cancelled. This method |
451 |
< |
* may be invoked only from within ForkJoinTask |
452 |
< |
* computations. Attempts to invoke in other contexts resul!t in |
453 |
< |
* exceptions or errors possibly including ClassCastException. |
448 |
> |
* Forks all tasks in the specified collection, returning when |
449 |
> |
* {@code isDone} holds for each task or an (unchecked) exception |
450 |
> |
* is encountered, in which case the exception is rethrown. If |
451 |
> |
* more than one task encounters an exception, then this method |
452 |
> |
* throws any one of these exceptions. If any task encounters an |
453 |
> |
* exception, others may be cancelled. However, the execution |
454 |
> |
* status of individual tasks is not guaranteed upon exceptional |
455 |
> |
* return. The status of each task may be obtained using {@link |
456 |
> |
* #getException()} and related methods to check if they have been |
457 |
> |
* cancelled, completed normally or exceptionally, or left |
458 |
> |
* unprocessed. |
459 |
> |
* |
460 |
> |
* <p>This method may be invoked only from within {@code |
461 |
> |
* ForkJoinTask} computations (as may be determined using method |
462 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
463 |
> |
* result in exceptions or errors, possibly including {@code |
464 |
> |
* ClassCastException}. |
465 |
> |
* |
466 |
|
* @param tasks the collection of tasks |
467 |
< |
* @throws NullPointerException if tasks or any element are null. |
468 |
< |
* @throws RuntimeException or Error if any task did so. |
467 |
> |
* @return the tasks argument, to simplify usage |
468 |
> |
* @throws NullPointerException if tasks or any element are null |
469 |
|
*/ |
470 |
< |
public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) { |
471 |
< |
if (!(tasks instanceof List)) { |
472 |
< |
invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()])); |
473 |
< |
return; |
470 |
> |
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
471 |
> |
if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) { |
472 |
> |
invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()])); |
473 |
> |
return tasks; |
474 |
|
} |
475 |
+ |
@SuppressWarnings("unchecked") |
476 |
|
List<? extends ForkJoinTask<?>> ts = |
477 |
< |
(List<? extends ForkJoinTask<?>>)tasks; |
477 |
> |
(List<? extends ForkJoinTask<?>>) tasks; |
478 |
|
Throwable ex = null; |
479 |
|
int last = ts.size() - 1; |
480 |
|
for (int i = last; i >= 0; --i) { |
487 |
|
t.fork(); |
488 |
|
else { |
489 |
|
t.quietlyInvoke(); |
490 |
< |
if (ex == null) |
490 |
> |
if (ex == null && t.status < NORMAL) |
491 |
|
ex = t.getException(); |
492 |
|
} |
493 |
|
} |
498 |
|
t.cancel(false); |
499 |
|
else { |
500 |
|
t.quietlyJoin(); |
501 |
< |
if (ex == null) |
501 |
> |
if (ex == null && t.status < NORMAL) |
502 |
|
ex = t.getException(); |
503 |
|
} |
504 |
|
} |
505 |
|
} |
506 |
|
if (ex != null) |
507 |
< |
rethrowException(ex); |
508 |
< |
} |
622 |
< |
|
623 |
< |
/** |
624 |
< |
* Returns true if the computation performed by this task has |
625 |
< |
* completed (or has been cancelled). |
626 |
< |
* @return true if this computation has completed |
627 |
< |
*/ |
628 |
< |
public final boolean isDone() { |
629 |
< |
return status < 0; |
630 |
< |
} |
631 |
< |
|
632 |
< |
/** |
633 |
< |
* Returns true if this task was cancelled. |
634 |
< |
* @return true if this task was cancelled |
635 |
< |
*/ |
636 |
< |
public final boolean isCancelled() { |
637 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
507 |
> |
UNSAFE.throwException(ex); |
508 |
> |
return tasks; |
509 |
|
} |
510 |
|
|
511 |
|
/** |
512 |
< |
* Asserts that the results of this task's computation will not be |
513 |
< |
* used. If a cancellation occurs before atempting to execute this |
514 |
< |
* task, then execution will be suppressed, {@code isCancelled} |
515 |
< |
* will report true, and {@code join} will result in a |
516 |
< |
* {@code CancellationException} being thrown. Otherwise, when |
517 |
< |
* cancellation races with completion, there are no guarantees |
518 |
< |
* about whether {@code isCancelled} will report true, whether |
648 |
< |
* {@code join} will return normally or via an exception, or |
649 |
< |
* whether these behaviors will remain consistent upon repeated |
650 |
< |
* invocation. |
512 |
> |
* Attempts to cancel execution of this task. This attempt will |
513 |
> |
* fail if the task has already completed, has already been |
514 |
> |
* cancelled, or could not be cancelled for some other reason. If |
515 |
> |
* successful, and this task has not started when cancel is |
516 |
> |
* called, execution of this task is suppressed, {@link |
517 |
> |
* #isCancelled} will report true, and {@link #join} will result |
518 |
> |
* in a {@code CancellationException} being thrown. |
519 |
|
* |
520 |
|
* <p>This method may be overridden in subclasses, but if so, must |
521 |
|
* still ensure that these minimal properties hold. In particular, |
522 |
< |
* the cancel method itself must not throw exceptions. |
522 |
> |
* the {@code cancel} method itself must not throw exceptions. |
523 |
|
* |
524 |
< |
* <p> This method is designed to be invoked by <em>other</em> |
524 |
> |
* <p>This method is designed to be invoked by <em>other</em> |
525 |
|
* tasks. To terminate the current task, you can just return or |
526 |
|
* throw an unchecked exception from its computation method, or |
527 |
< |
* invoke {@code completeExceptionally}. |
527 |
> |
* invoke {@link #completeExceptionally}. |
528 |
|
* |
529 |
|
* @param mayInterruptIfRunning this value is ignored in the |
530 |
< |
* default implementation because tasks are not in general |
531 |
< |
* cancelled via interruption. |
530 |
> |
* default implementation because tasks are not |
531 |
> |
* cancelled via interruption |
532 |
|
* |
533 |
< |
* @return true if this task is now cancelled |
533 |
> |
* @return {@code true} if this task is now cancelled |
534 |
|
*/ |
535 |
|
public boolean cancel(boolean mayInterruptIfRunning) { |
536 |
|
setCompletion(CANCELLED); |
537 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
537 |
> |
return status == CANCELLED; |
538 |
> |
} |
539 |
> |
|
540 |
> |
/** |
541 |
> |
* Cancels, ignoring any exceptions thrown by cancel. Used during |
542 |
> |
* worker and pool shutdown. Cancel is spec'ed not to throw any |
543 |
> |
* exceptions, but if it does anyway, we have no recourse during |
544 |
> |
* shutdown, so guard against this case. |
545 |
> |
*/ |
546 |
> |
final void cancelIgnoringExceptions() { |
547 |
> |
try { |
548 |
> |
cancel(false); |
549 |
> |
} catch (Throwable ignore) { |
550 |
> |
} |
551 |
> |
} |
552 |
> |
|
553 |
> |
/** |
554 |
> |
* Cancels if current thread is a terminating worker thread, |
555 |
> |
* ignoring any exceptions thrown by cancel. |
556 |
> |
*/ |
557 |
> |
final void cancelIfTerminating() { |
558 |
> |
Thread t = Thread.currentThread(); |
559 |
> |
if ((t instanceof ForkJoinWorkerThread) && |
560 |
> |
((ForkJoinWorkerThread) t).isTerminating()) { |
561 |
> |
try { |
562 |
> |
cancel(false); |
563 |
> |
} catch (Throwable ignore) { |
564 |
> |
} |
565 |
> |
} |
566 |
> |
} |
567 |
> |
|
568 |
> |
public final boolean isDone() { |
569 |
> |
return status < 0; |
570 |
> |
} |
571 |
> |
|
572 |
> |
public final boolean isCancelled() { |
573 |
> |
return status == CANCELLED; |
574 |
|
} |
575 |
|
|
576 |
|
/** |
577 |
< |
* Returns true if this task threw an exception or was cancelled |
578 |
< |
* @return true if this task threw an exception or was cancelled |
577 |
> |
* Returns {@code true} if this task threw an exception or was cancelled. |
578 |
> |
* |
579 |
> |
* @return {@code true} if this task threw an exception or was cancelled |
580 |
|
*/ |
581 |
|
public final boolean isCompletedAbnormally() { |
582 |
< |
return (status & COMPLETION_MASK) < NORMAL; |
582 |
> |
return status < NORMAL; |
583 |
> |
} |
584 |
> |
|
585 |
> |
/** |
586 |
> |
* Returns {@code true} if this task completed without throwing an |
587 |
> |
* exception and was not cancelled. |
588 |
> |
* |
589 |
> |
* @return {@code true} if this task completed without throwing an |
590 |
> |
* exception and was not cancelled |
591 |
> |
*/ |
592 |
> |
public final boolean isCompletedNormally() { |
593 |
> |
return status == NORMAL; |
594 |
|
} |
595 |
|
|
596 |
|
/** |
597 |
|
* Returns the exception thrown by the base computation, or a |
598 |
< |
* CancellationException if cancelled, or null if none or if the |
599 |
< |
* method has not yet completed. |
600 |
< |
* @return the exception, or null if none |
598 |
> |
* {@code CancellationException} if cancelled, or {@code null} if |
599 |
> |
* none or if the method has not yet completed. |
600 |
> |
* |
601 |
> |
* @return the exception, or {@code null} if none |
602 |
|
*/ |
603 |
|
public final Throwable getException() { |
604 |
< |
int s = status & COMPLETION_MASK; |
605 |
< |
if (s >= NORMAL) |
606 |
< |
return null; |
607 |
< |
if (s == CANCELLED) |
691 |
< |
return new CancellationException(); |
692 |
< |
return exceptionMap.get(this); |
604 |
> |
int s = status; |
605 |
> |
return ((s >= NORMAL) ? null : |
606 |
> |
(s == CANCELLED) ? new CancellationException() : |
607 |
> |
exceptionMap.get(this)); |
608 |
|
} |
609 |
|
|
610 |
|
/** |
613 |
|
* {@code join} and related operations. This method may be used |
614 |
|
* to induce exceptions in asynchronous tasks, or to force |
615 |
|
* completion of tasks that would not otherwise complete. Its use |
616 |
< |
* in other situations is likely to be wrong. This method is |
616 |
> |
* in other situations is discouraged. This method is |
617 |
|
* overridable, but overridden versions must invoke {@code super} |
618 |
|
* implementation to maintain guarantees. |
619 |
|
* |
620 |
< |
* @param ex the exception to throw. If this exception is |
621 |
< |
* not a RuntimeException or Error, the actual exception thrown |
622 |
< |
* will be a RuntimeException with cause ex. |
620 |
> |
* @param ex the exception to throw. If this exception is not a |
621 |
> |
* {@code RuntimeException} or {@code Error}, the actual exception |
622 |
> |
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
623 |
|
*/ |
624 |
|
public void completeExceptionally(Throwable ex) { |
625 |
< |
setDoneExceptionally((ex instanceof RuntimeException) || |
626 |
< |
(ex instanceof Error)? ex : |
627 |
< |
new RuntimeException(ex)); |
625 |
> |
setExceptionalCompletion((ex instanceof RuntimeException) || |
626 |
> |
(ex instanceof Error) ? ex : |
627 |
> |
new RuntimeException(ex)); |
628 |
|
} |
629 |
|
|
630 |
|
/** |
631 |
|
* Completes this task, and if not already aborted or cancelled, |
632 |
< |
* returning a {@code null} result upon {@code join} and related |
633 |
< |
* operations. This method may be used to provide results for |
634 |
< |
* asynchronous tasks, or to provide alternative handling for |
635 |
< |
* tasks that would not otherwise complete normally. Its use in |
636 |
< |
* other situations is likely to be wrong. This method is |
637 |
< |
* overridable, but overridden versions must invoke {@code super} |
638 |
< |
* implementation to maintain guarantees. |
632 |
> |
* returning the given value as the result of subsequent |
633 |
> |
* invocations of {@code join} and related operations. This method |
634 |
> |
* may be used to provide results for asynchronous tasks, or to |
635 |
> |
* provide alternative handling for tasks that would not otherwise |
636 |
> |
* complete normally. Its use in other situations is |
637 |
> |
* discouraged. This method is overridable, but overridden |
638 |
> |
* versions must invoke {@code super} implementation to maintain |
639 |
> |
* guarantees. |
640 |
|
* |
641 |
< |
* @param value the result value for this task. |
641 |
> |
* @param value the result value for this task |
642 |
|
*/ |
643 |
|
public void complete(V value) { |
644 |
|
try { |
645 |
|
setRawResult(value); |
646 |
< |
} catch(Throwable rex) { |
647 |
< |
setDoneExceptionally(rex); |
646 |
> |
} catch (Throwable rex) { |
647 |
> |
setExceptionalCompletion(rex); |
648 |
|
return; |
649 |
|
} |
650 |
< |
setNormalCompletion(); |
735 |
< |
} |
736 |
< |
|
737 |
< |
public final V get() throws InterruptedException, ExecutionException { |
738 |
< |
ForkJoinWorkerThread w = getWorker(); |
739 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
740 |
< |
awaitDone(w, true); |
741 |
< |
return reportFutureResult(); |
742 |
< |
} |
743 |
< |
|
744 |
< |
public final V get(long timeout, TimeUnit unit) |
745 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
746 |
< |
ForkJoinWorkerThread w = getWorker(); |
747 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
748 |
< |
awaitDone(w, unit.toNanos(timeout)); |
749 |
< |
return reportTimedFutureResult(); |
650 |
> |
setCompletion(NORMAL); |
651 |
|
} |
652 |
|
|
653 |
|
/** |
654 |
< |
* Possibly executes other tasks until this task is ready, then |
655 |
< |
* returns the result of the computation. This method may be more |
656 |
< |
* efficient than {@code join}, but is only applicable when |
756 |
< |
* there are no potemtial dependencies between continuation of the |
757 |
< |
* current task and that of any other task that might be executed |
758 |
< |
* while helping. (This usually holds for pure divide-and-conquer |
759 |
< |
* tasks). This method may be invoked only from within |
760 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
761 |
< |
* resul!t in exceptions or errors possibly including ClassCastException. |
654 |
> |
* Waits if necessary for the computation to complete, and then |
655 |
> |
* retrieves its result. |
656 |
> |
* |
657 |
|
* @return the computed result |
658 |
+ |
* @throws CancellationException if the computation was cancelled |
659 |
+ |
* @throws ExecutionException if the computation threw an |
660 |
+ |
* exception |
661 |
+ |
* @throws InterruptedException if the current thread is not a |
662 |
+ |
* member of a ForkJoinPool and was interrupted while waiting |
663 |
|
*/ |
664 |
< |
public final V helpJoin() { |
665 |
< |
ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread()); |
666 |
< |
if (status < 0 || !w.unpushTask(this) || !tryExec()) |
667 |
< |
reportException(busyJoin(w)); |
664 |
> |
public final V get() throws InterruptedException, ExecutionException { |
665 |
> |
int s; |
666 |
> |
if (Thread.currentThread() instanceof ForkJoinWorkerThread) { |
667 |
> |
quietlyJoin(); |
668 |
> |
s = status; |
669 |
> |
} |
670 |
> |
else { |
671 |
> |
while ((s = status) >= 0) { |
672 |
> |
synchronized (this) { // interruptible form of awaitDone |
673 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, |
674 |
> |
s, SIGNAL)) { |
675 |
> |
while (status >= 0) |
676 |
> |
wait(); |
677 |
> |
} |
678 |
> |
} |
679 |
> |
} |
680 |
> |
} |
681 |
> |
if (s < NORMAL) { |
682 |
> |
Throwable ex; |
683 |
> |
if (s == CANCELLED) |
684 |
> |
throw new CancellationException(); |
685 |
> |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
686 |
> |
throw new ExecutionException(ex); |
687 |
> |
} |
688 |
|
return getRawResult(); |
689 |
|
} |
690 |
|
|
691 |
|
/** |
692 |
< |
* Possibly executes other tasks until this task is ready. This |
693 |
< |
* method may be invoked only from within ForkJoinTask |
694 |
< |
* computations. Attempts to invoke in other contexts resul!t in |
695 |
< |
* exceptions or errors possibly including ClassCastException. |
692 |
> |
* Waits if necessary for at most the given time for the computation |
693 |
> |
* to complete, and then retrieves its result, if available. |
694 |
> |
* |
695 |
> |
* @param timeout the maximum time to wait |
696 |
> |
* @param unit the time unit of the timeout argument |
697 |
> |
* @return the computed result |
698 |
> |
* @throws CancellationException if the computation was cancelled |
699 |
> |
* @throws ExecutionException if the computation threw an |
700 |
> |
* exception |
701 |
> |
* @throws InterruptedException if the current thread is not a |
702 |
> |
* member of a ForkJoinPool and was interrupted while waiting |
703 |
> |
* @throws TimeoutException if the wait timed out |
704 |
|
*/ |
705 |
< |
public final void quietlyHelpJoin() { |
705 |
> |
public final V get(long timeout, TimeUnit unit) |
706 |
> |
throws InterruptedException, ExecutionException, TimeoutException { |
707 |
> |
long nanos = unit.toNanos(timeout); |
708 |
|
if (status >= 0) { |
709 |
< |
ForkJoinWorkerThread w = |
710 |
< |
(ForkJoinWorkerThread)(Thread.currentThread()); |
711 |
< |
if (!w.unpushTask(this) || !tryQuietlyInvoke()) |
712 |
< |
busyJoin(w); |
709 |
> |
Thread t = Thread.currentThread(); |
710 |
> |
if (t instanceof ForkJoinWorkerThread) { |
711 |
> |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
712 |
> |
boolean completed = false; // timed variant of quietlyJoin |
713 |
> |
if (w.unpushTask(this)) { |
714 |
> |
try { |
715 |
> |
completed = exec(); |
716 |
> |
} catch (Throwable rex) { |
717 |
> |
setExceptionalCompletion(rex); |
718 |
> |
} |
719 |
> |
} |
720 |
> |
if (completed) |
721 |
> |
setCompletion(NORMAL); |
722 |
> |
else if (status >= 0) |
723 |
> |
w.joinTask(this, true, nanos); |
724 |
> |
} |
725 |
> |
else if (Thread.interrupted()) |
726 |
> |
throw new InterruptedException(); |
727 |
> |
else { |
728 |
> |
long startTime = System.nanoTime(); |
729 |
> |
int s; long nt; |
730 |
> |
while ((s = status) >= 0 && |
731 |
> |
(nt = nanos - (System.nanoTime() - startTime)) > 0) { |
732 |
> |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, |
733 |
> |
SIGNAL)) { |
734 |
> |
long ms = nt / 1000000; |
735 |
> |
int ns = (int) (nt % 1000000); |
736 |
> |
synchronized (this) { |
737 |
> |
if (status >= 0) |
738 |
> |
wait(ms, ns); // exit on IE throw |
739 |
> |
} |
740 |
> |
} |
741 |
> |
} |
742 |
> |
} |
743 |
> |
} |
744 |
> |
int es = status; |
745 |
> |
if (es != NORMAL) { |
746 |
> |
Throwable ex; |
747 |
> |
if (es == CANCELLED) |
748 |
> |
throw new CancellationException(); |
749 |
> |
if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
750 |
> |
throw new ExecutionException(ex); |
751 |
> |
throw new TimeoutException(); |
752 |
|
} |
753 |
+ |
return getRawResult(); |
754 |
|
} |
755 |
|
|
756 |
|
/** |
757 |
< |
* Joins this task, without returning its result or throwing an |
757 |
> |
* Joins this task, without returning its result or throwing its |
758 |
|
* exception. This method may be useful when processing |
759 |
|
* collections of tasks when some have been cancelled or otherwise |
760 |
|
* known to have aborted. |
761 |
|
*/ |
762 |
|
public final void quietlyJoin() { |
763 |
< |
if (status >= 0) { |
764 |
< |
ForkJoinWorkerThread w = getWorker(); |
765 |
< |
if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke()) |
766 |
< |
awaitDone(w, true); |
763 |
> |
Thread t; |
764 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) { |
765 |
> |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
766 |
> |
if (status >= 0) { |
767 |
> |
if (w.unpushTask(this)) { |
768 |
> |
boolean completed; |
769 |
> |
try { |
770 |
> |
completed = exec(); |
771 |
> |
} catch (Throwable rex) { |
772 |
> |
setExceptionalCompletion(rex); |
773 |
> |
return; |
774 |
> |
} |
775 |
> |
if (completed) { |
776 |
> |
setCompletion(NORMAL); |
777 |
> |
return; |
778 |
> |
} |
779 |
> |
} |
780 |
> |
w.joinTask(this, false, 0L); |
781 |
> |
} |
782 |
|
} |
783 |
+ |
else |
784 |
+ |
externalAwaitDone(); |
785 |
|
} |
786 |
|
|
787 |
|
/** |
788 |
|
* Commences performing this task and awaits its completion if |
789 |
< |
* necessary, without returning its result or throwing an |
790 |
< |
* exception. This method may be useful when processing |
804 |
< |
* collections of tasks when some have been cancelled or otherwise |
805 |
< |
* known to have aborted. |
789 |
> |
* necessary, without returning its result or throwing its |
790 |
> |
* exception. |
791 |
|
*/ |
792 |
|
public final void quietlyInvoke() { |
793 |
< |
if (status >= 0 && !tryQuietlyInvoke()) |
794 |
< |
quietlyJoin(); |
793 |
> |
if (status >= 0) { |
794 |
> |
boolean completed; |
795 |
> |
try { |
796 |
> |
completed = exec(); |
797 |
> |
} catch (Throwable rex) { |
798 |
> |
setExceptionalCompletion(rex); |
799 |
> |
return; |
800 |
> |
} |
801 |
> |
if (completed) |
802 |
> |
setCompletion(NORMAL); |
803 |
> |
else |
804 |
> |
quietlyJoin(); |
805 |
> |
} |
806 |
|
} |
807 |
|
|
808 |
|
/** |
809 |
|
* Possibly executes tasks until the pool hosting the current task |
810 |
< |
* {@link ForkJoinPool#isQuiescent}. This method may be of use in |
811 |
< |
* designs in which many tasks are forked, but none are explicitly |
812 |
< |
* joined, instead executing them until all are processed. |
810 |
> |
* {@link ForkJoinPool#isQuiescent is quiescent}. This method may |
811 |
> |
* be of use in designs in which many tasks are forked, but none |
812 |
> |
* are explicitly joined, instead executing them until all are |
813 |
> |
* processed. |
814 |
> |
* |
815 |
> |
* <p>This method may be invoked only from within {@code |
816 |
> |
* ForkJoinTask} computations (as may be determined using method |
817 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
818 |
> |
* result in exceptions or errors, possibly including {@code |
819 |
> |
* ClassCastException}. |
820 |
|
*/ |
821 |
|
public static void helpQuiesce() { |
822 |
< |
((ForkJoinWorkerThread)(Thread.currentThread())). |
823 |
< |
helpQuiescePool(); |
822 |
> |
((ForkJoinWorkerThread) Thread.currentThread()) |
823 |
> |
.helpQuiescePool(); |
824 |
|
} |
825 |
|
|
826 |
|
/** |
829 |
|
* this task, but only if reuse occurs when this task has either |
830 |
|
* never been forked, or has been forked, then completed and all |
831 |
|
* outstanding joins of this task have also completed. Effects |
832 |
< |
* under any other usage conditions are not guaranteed, and are |
833 |
< |
* almost surely wrong. This method may be useful when executing |
832 |
> |
* under any other usage conditions are not guaranteed. |
833 |
> |
* This method may be useful when executing |
834 |
|
* pre-constructed trees of subtasks in loops. |
835 |
+ |
* |
836 |
+ |
* <p>Upon completion of this method, {@code isDone()} reports |
837 |
+ |
* {@code false}, and {@code getException()} reports {@code |
838 |
+ |
* null}. However, the value returned by {@code getRawResult} is |
839 |
+ |
* unaffected. To clear this value, you can invoke {@code |
840 |
+ |
* setRawResult(null)}. |
841 |
|
*/ |
842 |
|
public void reinitialize() { |
843 |
< |
if ((status & COMPLETION_MASK) == EXCEPTIONAL) |
843 |
> |
if (status == EXCEPTIONAL) |
844 |
|
exceptionMap.remove(this); |
845 |
|
status = 0; |
846 |
|
} |
847 |
|
|
848 |
|
/** |
849 |
|
* Returns the pool hosting the current task execution, or null |
850 |
< |
* if this task is executing outside of any pool. |
851 |
< |
* @return the pool, or null if none. |
850 |
> |
* if this task is executing outside of any ForkJoinPool. |
851 |
> |
* |
852 |
> |
* @see #inForkJoinPool |
853 |
> |
* @return the pool, or {@code null} if none |
854 |
|
*/ |
855 |
|
public static ForkJoinPool getPool() { |
856 |
|
Thread t = Thread.currentThread(); |
857 |
< |
return ((t instanceof ForkJoinWorkerThread)? |
858 |
< |
((ForkJoinWorkerThread)t).pool : null); |
857 |
> |
return (t instanceof ForkJoinWorkerThread) ? |
858 |
> |
((ForkJoinWorkerThread) t).pool : null; |
859 |
> |
} |
860 |
> |
|
861 |
> |
/** |
862 |
> |
* Returns {@code true} if the current thread is executing as a |
863 |
> |
* ForkJoinPool computation. |
864 |
> |
* |
865 |
> |
* @return {@code true} if the current thread is executing as a |
866 |
> |
* ForkJoinPool computation, or false otherwise |
867 |
> |
*/ |
868 |
> |
public static boolean inForkJoinPool() { |
869 |
> |
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
870 |
|
} |
871 |
|
|
872 |
|
/** |
875 |
|
* by the current thread, and has not commenced executing in |
876 |
|
* another thread. This method may be useful when arranging |
877 |
|
* alternative local processing of tasks that could have been, but |
878 |
< |
* were not, stolen. This method may be invoked only from within |
879 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
880 |
< |
* result in exceptions or errors possibly including ClassCastException. |
881 |
< |
* @return true if unforked |
878 |
> |
* were not, stolen. |
879 |
> |
* |
880 |
> |
* <p>This method may be invoked only from within {@code |
881 |
> |
* ForkJoinTask} computations (as may be determined using method |
882 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
883 |
> |
* result in exceptions or errors, possibly including {@code |
884 |
> |
* ClassCastException}. |
885 |
> |
* |
886 |
> |
* @return {@code true} if unforked |
887 |
|
*/ |
888 |
|
public boolean tryUnfork() { |
889 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this); |
889 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
890 |
> |
.unpushTask(this); |
891 |
|
} |
892 |
|
|
893 |
|
/** |
895 |
|
* forked by the current worker thread but not yet executed. This |
896 |
|
* value may be useful for heuristic decisions about whether to |
897 |
|
* fork other tasks. |
898 |
+ |
* |
899 |
+ |
* <p>This method may be invoked only from within {@code |
900 |
+ |
* ForkJoinTask} computations (as may be determined using method |
901 |
+ |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
902 |
+ |
* result in exceptions or errors, possibly including {@code |
903 |
+ |
* ClassCastException}. |
904 |
+ |
* |
905 |
|
* @return the number of tasks |
906 |
|
*/ |
907 |
|
public static int getQueuedTaskCount() { |
908 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
909 |
< |
getQueueSize(); |
908 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
909 |
> |
.getQueueSize(); |
910 |
|
} |
911 |
|
|
912 |
|
/** |
913 |
< |
* Returns a estimate of how many more locally queued tasks are |
913 |
> |
* Returns an estimate of how many more locally queued tasks are |
914 |
|
* held by the current worker thread than there are other worker |
915 |
|
* threads that might steal them. This value may be useful for |
916 |
|
* heuristic decisions about whether to fork other tasks. In many |
918 |
|
* aim to maintain a small constant surplus (for example, 3) of |
919 |
|
* tasks, and to process computations locally if this threshold is |
920 |
|
* exceeded. |
921 |
+ |
* |
922 |
+ |
* <p>This method may be invoked only from within {@code |
923 |
+ |
* ForkJoinTask} computations (as may be determined using method |
924 |
+ |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
925 |
+ |
* result in exceptions or errors, possibly including {@code |
926 |
+ |
* ClassCastException}. |
927 |
+ |
* |
928 |
|
* @return the surplus number of tasks, which may be negative |
929 |
|
*/ |
930 |
|
public static int getSurplusQueuedTaskCount() { |
931 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())) |
931 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
932 |
|
.getEstimatedSurplusTaskCount(); |
933 |
|
} |
934 |
|
|
935 |
|
// Extension methods |
936 |
|
|
937 |
|
/** |
938 |
< |
* Returns the result that would be returned by {@code join}, |
939 |
< |
* even if this task completed abnormally, or null if this task is |
940 |
< |
* not known to have been completed. This method is designed to |
941 |
< |
* aid debugging, as well as to support extensions. Its use in any |
942 |
< |
* other context is discouraged. |
938 |
> |
* Returns the result that would be returned by {@link #join}, even |
939 |
> |
* if this task completed abnormally, or {@code null} if this task |
940 |
> |
* is not known to have been completed. This method is designed |
941 |
> |
* to aid debugging, as well as to support extensions. Its use in |
942 |
> |
* any other context is discouraged. |
943 |
|
* |
944 |
< |
* @return the result, or null if not completed. |
944 |
> |
* @return the result, or {@code null} if not completed |
945 |
|
*/ |
946 |
|
public abstract V getRawResult(); |
947 |
|
|
960 |
|
* called otherwise. The return value controls whether this task |
961 |
|
* is considered to be done normally. It may return false in |
962 |
|
* asynchronous actions that require explicit invocations of |
963 |
< |
* {@code complete} to become joinable. It may throw exceptions |
964 |
< |
* to indicate abnormal exit. |
965 |
< |
* @return true if completed normally |
966 |
< |
* @throws Error or RuntimeException if encountered during computation |
963 |
> |
* {@link #complete} to become joinable. It may also throw an |
964 |
> |
* (unchecked) exception to indicate abnormal exit. |
965 |
> |
* |
966 |
> |
* @return {@code true} if completed normally |
967 |
|
*/ |
968 |
|
protected abstract boolean exec(); |
969 |
|
|
970 |
|
/** |
971 |
< |
* Returns, but does not unschedule or execute, the task queued by |
972 |
< |
* the current thread but not yet executed, if one is |
971 |
> |
* Returns, but does not unschedule or execute, a task queued by |
972 |
> |
* the current thread but not yet executed, if one is immediately |
973 |
|
* available. There is no guarantee that this task will actually |
974 |
< |
* be polled or executed next. This method is designed primarily |
975 |
< |
* to support extensions, and is unlikely to be useful otherwise. |
976 |
< |
* This method may be invoked only from within ForkJoinTask |
977 |
< |
* computations. Attempts to invoke in other contexts result in |
978 |
< |
* exceptions or errors possibly including ClassCastException. |
974 |
> |
* be polled or executed next. Conversely, this method may return |
975 |
> |
* null even if a task exists but cannot be accessed without |
976 |
> |
* contention with other threads. This method is designed |
977 |
> |
* primarily to support extensions, and is unlikely to be useful |
978 |
> |
* otherwise. |
979 |
> |
* |
980 |
> |
* <p>This method may be invoked only from within {@code |
981 |
> |
* ForkJoinTask} computations (as may be determined using method |
982 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
983 |
> |
* result in exceptions or errors, possibly including {@code |
984 |
> |
* ClassCastException}. |
985 |
|
* |
986 |
< |
* @return the next task, or null if none are available |
986 |
> |
* @return the next task, or {@code null} if none are available |
987 |
|
*/ |
988 |
|
protected static ForkJoinTask<?> peekNextLocalTask() { |
989 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).peekTask(); |
989 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
990 |
> |
.peekTask(); |
991 |
|
} |
992 |
|
|
993 |
|
/** |
994 |
|
* Unschedules and returns, without executing, the next task |
995 |
|
* queued by the current thread but not yet executed. This method |
996 |
|
* is designed primarily to support extensions, and is unlikely to |
997 |
< |
* be useful otherwise. This method may be invoked only from |
949 |
< |
* within ForkJoinTask computations. Attempts to invoke in other |
950 |
< |
* contexts result in exceptions or errors possibly including |
951 |
< |
* ClassCastException. |
997 |
> |
* be useful otherwise. |
998 |
|
* |
999 |
< |
* @return the next task, or null if none are available |
999 |
> |
* <p>This method may be invoked only from within {@code |
1000 |
> |
* ForkJoinTask} computations (as may be determined using method |
1001 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1002 |
> |
* result in exceptions or errors, possibly including {@code |
1003 |
> |
* ClassCastException}. |
1004 |
> |
* |
1005 |
> |
* @return the next task, or {@code null} if none are available |
1006 |
|
*/ |
1007 |
|
protected static ForkJoinTask<?> pollNextLocalTask() { |
1008 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).pollLocalTask(); |
1008 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1009 |
> |
.pollLocalTask(); |
1010 |
|
} |
1011 |
|
|
1012 |
|
/** |
1014 |
|
* queued by the current thread but not yet executed, if one is |
1015 |
|
* available, or if not available, a task that was forked by some |
1016 |
|
* other thread, if available. Availability may be transient, so a |
1017 |
< |
* {@code null} result does not necessarily imply quiecence |
1017 |
> |
* {@code null} result does not necessarily imply quiescence |
1018 |
|
* of the pool this task is operating in. This method is designed |
1019 |
|
* primarily to support extensions, and is unlikely to be useful |
1020 |
< |
* otherwise. This method may be invoked only from within |
1021 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
1022 |
< |
* result in exceptions or errors possibly including |
1023 |
< |
* ClassCastException. |
1020 |
> |
* otherwise. |
1021 |
> |
* |
1022 |
> |
* <p>This method may be invoked only from within {@code |
1023 |
> |
* ForkJoinTask} computations (as may be determined using method |
1024 |
> |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1025 |
> |
* result in exceptions or errors, possibly including {@code |
1026 |
> |
* ClassCastException}. |
1027 |
|
* |
1028 |
< |
* @return a task, or null if none are available |
1028 |
> |
* @return a task, or {@code null} if none are available |
1029 |
|
*/ |
1030 |
|
protected static ForkJoinTask<?> pollTask() { |
1031 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
1032 |
< |
pollTask(); |
1031 |
> |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1032 |
> |
.pollTask(); |
1033 |
> |
} |
1034 |
> |
|
1035 |
> |
/** |
1036 |
> |
* Adaptor for Runnables. This implements RunnableFuture |
1037 |
> |
* to be compliant with AbstractExecutorService constraints |
1038 |
> |
* when used in ForkJoinPool. |
1039 |
> |
*/ |
1040 |
> |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
1041 |
> |
implements RunnableFuture<T> { |
1042 |
> |
final Runnable runnable; |
1043 |
> |
final T resultOnCompletion; |
1044 |
> |
T result; |
1045 |
> |
AdaptedRunnable(Runnable runnable, T result) { |
1046 |
> |
if (runnable == null) throw new NullPointerException(); |
1047 |
> |
this.runnable = runnable; |
1048 |
> |
this.resultOnCompletion = result; |
1049 |
> |
} |
1050 |
> |
public T getRawResult() { return result; } |
1051 |
> |
public void setRawResult(T v) { result = v; } |
1052 |
> |
public boolean exec() { |
1053 |
> |
runnable.run(); |
1054 |
> |
result = resultOnCompletion; |
1055 |
> |
return true; |
1056 |
> |
} |
1057 |
> |
public void run() { invoke(); } |
1058 |
> |
private static final long serialVersionUID = 5232453952276885070L; |
1059 |
> |
} |
1060 |
> |
|
1061 |
> |
/** |
1062 |
> |
* Adaptor for Callables |
1063 |
> |
*/ |
1064 |
> |
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
1065 |
> |
implements RunnableFuture<T> { |
1066 |
> |
final Callable<? extends T> callable; |
1067 |
> |
T result; |
1068 |
> |
AdaptedCallable(Callable<? extends T> callable) { |
1069 |
> |
if (callable == null) throw new NullPointerException(); |
1070 |
> |
this.callable = callable; |
1071 |
> |
} |
1072 |
> |
public T getRawResult() { return result; } |
1073 |
> |
public void setRawResult(T v) { result = v; } |
1074 |
> |
public boolean exec() { |
1075 |
> |
try { |
1076 |
> |
result = callable.call(); |
1077 |
> |
return true; |
1078 |
> |
} catch (Error err) { |
1079 |
> |
throw err; |
1080 |
> |
} catch (RuntimeException rex) { |
1081 |
> |
throw rex; |
1082 |
> |
} catch (Exception ex) { |
1083 |
> |
throw new RuntimeException(ex); |
1084 |
> |
} |
1085 |
> |
} |
1086 |
> |
public void run() { invoke(); } |
1087 |
> |
private static final long serialVersionUID = 2838392045355241008L; |
1088 |
> |
} |
1089 |
> |
|
1090 |
> |
/** |
1091 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1092 |
> |
* method of the given {@code Runnable} as its action, and returns |
1093 |
> |
* a null result upon {@link #join}. |
1094 |
> |
* |
1095 |
> |
* @param runnable the runnable action |
1096 |
> |
* @return the task |
1097 |
> |
*/ |
1098 |
> |
public static ForkJoinTask<?> adapt(Runnable runnable) { |
1099 |
> |
return new AdaptedRunnable<Void>(runnable, null); |
1100 |
> |
} |
1101 |
> |
|
1102 |
> |
/** |
1103 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1104 |
> |
* method of the given {@code Runnable} as its action, and returns |
1105 |
> |
* the given result upon {@link #join}. |
1106 |
> |
* |
1107 |
> |
* @param runnable the runnable action |
1108 |
> |
* @param result the result upon completion |
1109 |
> |
* @return the task |
1110 |
> |
*/ |
1111 |
> |
public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) { |
1112 |
> |
return new AdaptedRunnable<T>(runnable, result); |
1113 |
> |
} |
1114 |
> |
|
1115 |
> |
/** |
1116 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code call} |
1117 |
> |
* method of the given {@code Callable} as its action, and returns |
1118 |
> |
* its result upon {@link #join}, translating any checked exceptions |
1119 |
> |
* encountered into {@code RuntimeException}. |
1120 |
> |
* |
1121 |
> |
* @param callable the callable action |
1122 |
> |
* @return the task |
1123 |
> |
*/ |
1124 |
> |
public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) { |
1125 |
> |
return new AdaptedCallable<T>(callable); |
1126 |
|
} |
1127 |
|
|
1128 |
|
// Serialization support |
1130 |
|
private static final long serialVersionUID = -7721805057305804111L; |
1131 |
|
|
1132 |
|
/** |
1133 |
< |
* Save the state to a stream. |
1133 |
> |
* Saves the state to a stream (that is, serializes it). |
1134 |
|
* |
1135 |
|
* @serialData the current run status and the exception thrown |
1136 |
< |
* during execution, or null if none. |
1136 |
> |
* during execution, or {@code null} if none |
1137 |
|
* @param s the stream |
1138 |
|
*/ |
1139 |
|
private void writeObject(java.io.ObjectOutputStream s) |
1143 |
|
} |
1144 |
|
|
1145 |
|
/** |
1146 |
< |
* Reconstitute the instance from a stream. |
1146 |
> |
* Reconstitutes the instance from a stream (that is, deserializes it). |
1147 |
> |
* |
1148 |
|
* @param s the stream |
1149 |
|
*/ |
1150 |
|
private void readObject(java.io.ObjectInputStream s) |
1151 |
|
throws java.io.IOException, ClassNotFoundException { |
1152 |
|
s.defaultReadObject(); |
1003 |
– |
status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts |
1004 |
– |
status |= EXTERNAL_SIGNAL; // conservatively set external signal |
1153 |
|
Object ex = s.readObject(); |
1154 |
|
if (ex != null) |
1155 |
< |
setDoneExceptionally((Throwable)ex); |
1155 |
> |
setExceptionalCompletion((Throwable) ex); |
1156 |
|
} |
1157 |
|
|
1158 |
< |
// Temporary Unsafe mechanics for preliminary release |
1159 |
< |
private static Unsafe getUnsafe() throws Throwable { |
1158 |
> |
// Unsafe mechanics |
1159 |
> |
|
1160 |
> |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
1161 |
> |
private static final long statusOffset = |
1162 |
> |
objectFieldOffset("status", ForkJoinTask.class); |
1163 |
> |
|
1164 |
> |
private static long objectFieldOffset(String field, Class<?> klazz) { |
1165 |
|
try { |
1166 |
< |
return Unsafe.getUnsafe(); |
1166 |
> |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
1167 |
> |
} catch (NoSuchFieldException e) { |
1168 |
> |
// Convert Exception to corresponding Error |
1169 |
> |
NoSuchFieldError error = new NoSuchFieldError(field); |
1170 |
> |
error.initCause(e); |
1171 |
> |
throw error; |
1172 |
> |
} |
1173 |
> |
} |
1174 |
> |
|
1175 |
> |
/** |
1176 |
> |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1177 |
> |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1178 |
> |
* into a jdk. |
1179 |
> |
* |
1180 |
> |
* @return a sun.misc.Unsafe |
1181 |
> |
*/ |
1182 |
> |
private static sun.misc.Unsafe getUnsafe() { |
1183 |
> |
try { |
1184 |
> |
return sun.misc.Unsafe.getUnsafe(); |
1185 |
|
} catch (SecurityException se) { |
1186 |
|
try { |
1187 |
|
return java.security.AccessController.doPrivileged |
1188 |
< |
(new java.security.PrivilegedExceptionAction<Unsafe>() { |
1189 |
< |
public Unsafe run() throws Exception { |
1190 |
< |
return getUnsafePrivileged(); |
1188 |
> |
(new java.security |
1189 |
> |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1190 |
> |
public sun.misc.Unsafe run() throws Exception { |
1191 |
> |
java.lang.reflect.Field f = sun.misc |
1192 |
> |
.Unsafe.class.getDeclaredField("theUnsafe"); |
1193 |
> |
f.setAccessible(true); |
1194 |
> |
return (sun.misc.Unsafe) f.get(null); |
1195 |
|
}}); |
1196 |
|
} catch (java.security.PrivilegedActionException e) { |
1197 |
< |
throw e.getCause(); |
1197 |
> |
throw new RuntimeException("Could not initialize intrinsics", |
1198 |
> |
e.getCause()); |
1199 |
|
} |
1200 |
|
} |
1201 |
|
} |
1026 |
– |
|
1027 |
– |
private static Unsafe getUnsafePrivileged() |
1028 |
– |
throws NoSuchFieldException, IllegalAccessException { |
1029 |
– |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
1030 |
– |
f.setAccessible(true); |
1031 |
– |
return (Unsafe) f.get(null); |
1032 |
– |
} |
1033 |
– |
|
1034 |
– |
private static long fieldOffset(String fieldName) |
1035 |
– |
throws NoSuchFieldException { |
1036 |
– |
return _unsafe.objectFieldOffset |
1037 |
– |
(ForkJoinTask.class.getDeclaredField(fieldName)); |
1038 |
– |
} |
1039 |
– |
|
1040 |
– |
static final Unsafe _unsafe; |
1041 |
– |
static final long statusOffset; |
1042 |
– |
|
1043 |
– |
static { |
1044 |
– |
try { |
1045 |
– |
_unsafe = getUnsafe(); |
1046 |
– |
statusOffset = fieldOffset("status"); |
1047 |
– |
} catch (Throwable e) { |
1048 |
– |
throw new RuntimeException("Could not initialize intrinsics", e); |
1049 |
– |
} |
1050 |
– |
} |
1051 |
– |
|
1202 |
|
} |