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jsr166 |
1.1 |
/* |
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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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jsr166 |
1.48 |
* http://creativecommons.org/publicdomain/zero/1.0/ |
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jsr166 |
1.1 |
*/ |
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package java.util.concurrent; |
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import java.io.Serializable; |
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dl |
1.109 |
import java.lang.invoke.MethodHandles; |
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import java.lang.invoke.VarHandle; |
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jsr166 |
1.90 |
import java.lang.ref.ReferenceQueue; |
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import java.lang.ref.WeakReference; |
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import java.lang.reflect.Constructor; |
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jsr166 |
1.1 |
import java.util.Collection; |
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import java.util.List; |
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jsr166 |
1.7 |
import java.util.RandomAccess; |
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dl |
1.45 |
import java.util.concurrent.locks.ReentrantLock; |
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jsr166 |
1.1 |
|
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/** |
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jsr166 |
1.6 |
* 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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jsr166 |
1.1 |
* 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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dl |
1.64 |
* <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 |
30 |
dl |
1.67 |
* ForkJoinPool#commonPool()} via {@link #fork}, {@link #invoke}, or |
31 |
dl |
1.64 |
* 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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jsr166 |
1.27 |
* #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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dl |
1.64 |
* 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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jsr166 |
1.1 |
* |
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jsr166 |
1.6 |
* <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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dl |
1.54 |
* 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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jsr166 |
1.6 |
* 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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dl |
1.54 |
* 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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jsr166 |
1.68 |
* not perform blocking I/O, and should ideally access variables that |
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dl |
1.54 |
* 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>It is possible to define and use ForkJoinTasks that may block, |
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jsr166 |
1.110 |
* but doing so requires three further considerations: (1) Completion |
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dl |
1.54 |
* of few if any <em>other</em> tasks should be dependent on a task |
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jsr166 |
1.68 |
* that blocks on external synchronization or I/O. Event-style async |
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dl |
1.63 |
* 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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dl |
1.54 |
* 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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jsr166 |
1.1 |
* |
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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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dl |
1.16 |
* conventions. Method {@link #invoke} is semantically |
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jsr166 |
1.8 |
* 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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jsr166 |
1.1 |
* 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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jsr166 |
1.57 |
* <p>In the most typical usages, a fork-join pair act like a call |
96 |
dl |
1.54 |
* (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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jsr166 |
1.8 |
* <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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jsr166 |
1.10 |
* 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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jsr166 |
1.115 |
* returns a {@link CancellationException}); and |
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jsr166 |
1.10 |
* {@link #isCompletedAbnormally} is true if a task was either |
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* cancelled or encountered an exception, in which case {@link |
111 |
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* #getException} will return either the encountered exception or |
112 |
jsr166 |
1.115 |
* {@link CancellationException}. |
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jsr166 |
1.8 |
* |
114 |
jsr166 |
1.6 |
* <p>The ForkJoinTask class is not usually directly subclassed. |
115 |
jsr166 |
1.1 |
* Instead, you subclass one of the abstract classes that support a |
116 |
jsr166 |
1.6 |
* particular style of fork/join processing, typically {@link |
117 |
dl |
1.62 |
* 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 |
122 |
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* then defines a {@code compute} method that somehow uses the control |
123 |
dl |
1.64 |
* methods supplied by this base class. |
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jsr166 |
1.1 |
* |
125 |
dl |
1.38 |
* <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 |
129 |
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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 |
132 |
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* may be of use in constructing custom subclasses for problems that |
133 |
jsr166 |
1.79 |
* are not statically structured as DAGs. To support such usages, a |
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dl |
1.63 |
* ForkJoinTask may be atomically <em>tagged</em> with a {@code short} |
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* value using {@link #setForkJoinTaskTag} or {@link |
136 |
dl |
1.60 |
* #compareAndSetForkJoinTaskTag} and checked using {@link |
137 |
dl |
1.63 |
* #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.) |
144 |
dl |
1.38 |
* |
145 |
jsr166 |
1.7 |
* <p>Most base support methods are {@code final}, to prevent |
146 |
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* overriding of implementations that are intrinsically tied to the |
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* underlying lightweight task scheduling framework. Developers |
148 |
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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 |
150 |
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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 |
152 |
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* subclasses, possibly relying on other {@code protected} methods |
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* provided by this class. |
154 |
jsr166 |
1.1 |
* |
155 |
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* <p>ForkJoinTasks should perform relatively small amounts of |
156 |
jsr166 |
1.7 |
* computation. Large tasks should be split into smaller subtasks, |
157 |
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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 |
159 |
dl |
1.40 |
* computational steps, and should avoid indefinite looping. If tasks |
160 |
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* are too big, then parallelism cannot improve throughput. If too |
161 |
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* small, then memory and internal task maintenance overhead may |
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* overwhelm processing. |
163 |
jsr166 |
1.1 |
* |
164 |
jsr166 |
1.8 |
* <p>This class provides {@code adapt} methods for {@link Runnable} |
165 |
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* and {@link Callable}, that may be of use when mixing execution of |
166 |
dl |
1.16 |
* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are |
167 |
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* of this form, consider using a pool constructed in <em>asyncMode</em>. |
168 |
jsr166 |
1.6 |
* |
169 |
jsr166 |
1.7 |
* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
170 |
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* used in extensions such as remote execution frameworks. It is |
171 |
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* sensible to serialize tasks only before or after, but not during, |
172 |
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* execution. Serialization is not relied on during execution itself. |
173 |
jsr166 |
1.1 |
* |
174 |
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* @since 1.7 |
175 |
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* @author Doug Lea |
176 |
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*/ |
177 |
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public abstract class ForkJoinTask<V> implements Future<V>, Serializable { |
178 |
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179 |
dl |
1.13 |
/* |
180 |
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* See the internal documentation of class ForkJoinPool for a |
181 |
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* general implementation overview. ForkJoinTasks are mainly |
182 |
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* responsible for maintaining their "status" field amidst relays |
183 |
jsr166 |
1.51 |
* to methods in ForkJoinWorkerThread and ForkJoinPool. |
184 |
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* |
185 |
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* The methods of this class are more-or-less layered into |
186 |
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* (1) basic status maintenance |
187 |
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* (2) execution and awaiting completion |
188 |
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* (3) user-level methods that additionally report results. |
189 |
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* This is sometimes hard to see because this file orders exported |
190 |
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* methods in a way that flows well in javadocs. |
191 |
dl |
1.13 |
*/ |
192 |
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193 |
dl |
1.17 |
/* |
194 |
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* The status field holds run control status bits packed into a |
195 |
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* single int to minimize footprint and to ensure atomicity (via |
196 |
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* CAS). Status is initially zero, and takes on nonnegative |
197 |
dl |
1.59 |
* values until completed, upon which status (anded with |
198 |
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* DONE_MASK) holds value NORMAL, CANCELLED, or EXCEPTIONAL. Tasks |
199 |
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* undergoing blocking waits by other threads have the SIGNAL bit |
200 |
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* set. Completion of a stolen task with SIGNAL set awakens any |
201 |
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* waiters via notifyAll. Even though suboptimal for some |
202 |
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* purposes, we use basic builtin wait/notify to take advantage of |
203 |
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* "monitor inflation" in JVMs that we would otherwise need to |
204 |
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* emulate to avoid adding further per-task bookkeeping overhead. |
205 |
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* We want these monitors to be "fat", i.e., not use biasing or |
206 |
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* thin-lock techniques, so use some odd coding idioms that tend |
207 |
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* to avoid them, mainly by arranging that every synchronized |
208 |
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* block performs a wait, notifyAll or both. |
209 |
dl |
1.60 |
* |
210 |
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* These control bits occupy only (some of) the upper half (16 |
211 |
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* bits) of status field. The lower bits are used for user-defined |
212 |
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* tags. |
213 |
jsr166 |
1.1 |
*/ |
214 |
dl |
1.17 |
|
215 |
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/** The run status of this task */ |
216 |
jsr166 |
1.1 |
volatile int status; // accessed directly by pool and workers |
217 |
dl |
1.59 |
static final int DONE_MASK = 0xf0000000; // mask out non-completion bits |
218 |
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static final int NORMAL = 0xf0000000; // must be negative |
219 |
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static final int CANCELLED = 0xc0000000; // must be < NORMAL |
220 |
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static final int EXCEPTIONAL = 0x80000000; // must be < CANCELLED |
221 |
dl |
1.60 |
static final int SIGNAL = 0x00010000; // must be >= 1 << 16 |
222 |
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static final int SMASK = 0x0000ffff; // short bits for tags |
223 |
jsr166 |
1.1 |
|
224 |
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/** |
225 |
dl |
1.54 |
* Marks completion and wakes up threads waiting to join this |
226 |
dl |
1.60 |
* task. |
227 |
dl |
1.13 |
* |
228 |
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* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL |
229 |
dl |
1.45 |
* @return completion status on exit |
230 |
jsr166 |
1.1 |
*/ |
231 |
dl |
1.45 |
private int setCompletion(int completion) { |
232 |
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for (int s;;) { |
233 |
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if ((s = status) < 0) |
234 |
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return s; |
235 |
dl |
1.109 |
if (STATUS.compareAndSet(this, s, s | completion)) { |
236 |
dl |
1.60 |
if ((s >>> 16) != 0) |
237 |
dl |
1.13 |
synchronized (this) { notifyAll(); } |
238 |
dl |
1.45 |
return completion; |
239 |
dl |
1.13 |
} |
240 |
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} |
241 |
jsr166 |
1.1 |
} |
242 |
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243 |
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/** |
244 |
dl |
1.54 |
* Primary execution method for stolen tasks. Unless done, calls |
245 |
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* exec and records status if completed, but doesn't wait for |
246 |
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* completion otherwise. |
247 |
jsr166 |
1.24 |
* |
248 |
dl |
1.54 |
* @return status on exit from this method |
249 |
jsr166 |
1.1 |
*/ |
250 |
dl |
1.54 |
final int doExec() { |
251 |
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int s; boolean completed; |
252 |
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if ((s = status) >= 0) { |
253 |
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try { |
254 |
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completed = exec(); |
255 |
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} catch (Throwable rex) { |
256 |
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return setExceptionalCompletion(rex); |
257 |
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} |
258 |
dl |
1.60 |
if (completed) |
259 |
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s = setCompletion(NORMAL); |
260 |
jsr166 |
1.1 |
} |
261 |
dl |
1.54 |
return s; |
262 |
jsr166 |
1.1 |
} |
263 |
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|
264 |
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/** |
265 |
dl |
1.87 |
* If not done, sets SIGNAL status and performs Object.wait(timeout). |
266 |
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* This task may or may not be done on exit. Ignores interrupts. |
267 |
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* |
268 |
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* @param timeout using Object.wait conventions. |
269 |
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*/ |
270 |
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final void internalWait(long timeout) { |
271 |
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int s; |
272 |
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if ((s = status) >= 0 && // force completer to issue notify |
273 |
dl |
1.109 |
STATUS.compareAndSet(this, s, s | SIGNAL)) { |
274 |
dl |
1.87 |
synchronized (this) { |
275 |
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if (status >= 0) |
276 |
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try { wait(timeout); } catch (InterruptedException ie) { } |
277 |
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else |
278 |
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notifyAll(); |
279 |
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} |
280 |
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} |
281 |
dl |
1.59 |
} |
282 |
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|
283 |
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/** |
284 |
dl |
1.40 |
* Blocks a non-worker-thread until completion. |
285 |
dl |
1.45 |
* @return status upon completion |
286 |
dl |
1.19 |
*/ |
287 |
dl |
1.45 |
private int externalAwaitDone() { |
288 |
dl |
1.87 |
int s = ((this instanceof CountedCompleter) ? // try helping |
289 |
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ForkJoinPool.common.externalHelpComplete( |
290 |
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(CountedCompleter<?>)this, 0) : |
291 |
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ForkJoinPool.common.tryExternalUnpush(this) ? doExec() : 0); |
292 |
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if (s >= 0 && (s = status) >= 0) { |
293 |
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boolean interrupted = false; |
294 |
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do { |
295 |
dl |
1.109 |
if (STATUS.compareAndSet(this, s, s | SIGNAL)) { |
296 |
dl |
1.87 |
synchronized (this) { |
297 |
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if (status >= 0) { |
298 |
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try { |
299 |
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wait(0L); |
300 |
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} catch (InterruptedException ie) { |
301 |
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interrupted = true; |
302 |
dl |
1.75 |
} |
303 |
dl |
1.43 |
} |
304 |
dl |
1.87 |
else |
305 |
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notifyAll(); |
306 |
dl |
1.40 |
} |
307 |
dl |
1.87 |
} |
308 |
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} while ((s = status) >= 0); |
309 |
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if (interrupted) |
310 |
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Thread.currentThread().interrupt(); |
311 |
dl |
1.19 |
} |
312 |
dl |
1.45 |
return s; |
313 |
dl |
1.19 |
} |
314 |
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|
315 |
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/** |
316 |
dl |
1.59 |
* Blocks a non-worker-thread until completion or interruption. |
317 |
jsr166 |
1.1 |
*/ |
318 |
dl |
1.59 |
private int externalInterruptibleAwaitDone() throws InterruptedException { |
319 |
dl |
1.66 |
int s; |
320 |
dl |
1.40 |
if (Thread.interrupted()) |
321 |
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throw new InterruptedException(); |
322 |
dl |
1.87 |
if ((s = status) >= 0 && |
323 |
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(s = ((this instanceof CountedCompleter) ? |
324 |
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ForkJoinPool.common.externalHelpComplete( |
325 |
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(CountedCompleter<?>)this, 0) : |
326 |
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ForkJoinPool.common.tryExternalUnpush(this) ? doExec() : |
327 |
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0)) >= 0) { |
328 |
|
|
while ((s = status) >= 0) { |
329 |
dl |
1.109 |
if (STATUS.compareAndSet(this, s, s | SIGNAL)) { |
330 |
dl |
1.87 |
synchronized (this) { |
331 |
|
|
if (status >= 0) |
332 |
|
|
wait(0L); |
333 |
|
|
else |
334 |
|
|
notifyAll(); |
335 |
|
|
} |
336 |
dl |
1.45 |
} |
337 |
|
|
} |
338 |
|
|
} |
339 |
|
|
return s; |
340 |
|
|
} |
341 |
|
|
|
342 |
|
|
/** |
343 |
dl |
1.54 |
* Implementation for join, get, quietlyJoin. Directly handles |
344 |
|
|
* only cases of already-completed, external wait, and |
345 |
dl |
1.59 |
* unfork+exec. Others are relayed to ForkJoinPool.awaitJoin. |
346 |
dl |
1.54 |
* |
347 |
|
|
* @return status upon completion |
348 |
dl |
1.45 |
*/ |
349 |
dl |
1.54 |
private int doJoin() { |
350 |
|
|
int s; Thread t; ForkJoinWorkerThread wt; ForkJoinPool.WorkQueue w; |
351 |
dl |
1.64 |
return (s = status) < 0 ? s : |
352 |
|
|
((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
353 |
|
|
(w = (wt = (ForkJoinWorkerThread)t).workQueue). |
354 |
|
|
tryUnpush(this) && (s = doExec()) < 0 ? s : |
355 |
dl |
1.87 |
wt.pool.awaitJoin(w, this, 0L) : |
356 |
dl |
1.64 |
externalAwaitDone(); |
357 |
jsr166 |
1.1 |
} |
358 |
|
|
|
359 |
|
|
/** |
360 |
dl |
1.54 |
* Implementation for invoke, quietlyInvoke. |
361 |
|
|
* |
362 |
dl |
1.45 |
* @return status upon completion |
363 |
jsr166 |
1.1 |
*/ |
364 |
dl |
1.45 |
private int doInvoke() { |
365 |
dl |
1.59 |
int s; Thread t; ForkJoinWorkerThread wt; |
366 |
dl |
1.64 |
return (s = doExec()) < 0 ? s : |
367 |
|
|
((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
368 |
dl |
1.87 |
(wt = (ForkJoinWorkerThread)t).pool. |
369 |
|
|
awaitJoin(wt.workQueue, this, 0L) : |
370 |
dl |
1.64 |
externalAwaitDone(); |
371 |
dl |
1.45 |
} |
372 |
|
|
|
373 |
|
|
// Exception table support |
374 |
|
|
|
375 |
|
|
/** |
376 |
jsr166 |
1.113 |
* Hash table of exceptions thrown by tasks, to enable reporting |
377 |
|
|
* by callers. Because exceptions are rare, we don't directly keep |
378 |
dl |
1.45 |
* them with task objects, but instead use a weak ref table. Note |
379 |
|
|
* that cancellation exceptions don't appear in the table, but are |
380 |
|
|
* instead recorded as status values. |
381 |
|
|
* |
382 |
jsr166 |
1.113 |
* The exception table has a fixed capacity. |
383 |
dl |
1.45 |
*/ |
384 |
jsr166 |
1.113 |
private static final ExceptionNode[] exceptionTable |
385 |
|
|
= new ExceptionNode[32]; |
386 |
dl |
1.45 |
|
387 |
jsr166 |
1.113 |
/** Lock protecting access to exceptionTable. */ |
388 |
|
|
private static final ReentrantLock exceptionTableLock |
389 |
|
|
= new ReentrantLock(); |
390 |
|
|
|
391 |
|
|
/** Reference queue of stale exceptionally completed tasks. */ |
392 |
|
|
private static final ReferenceQueue<ForkJoinTask<?>> exceptionTableRefQueue |
393 |
jsr166 |
1.114 |
= new ReferenceQueue<>(); |
394 |
dl |
1.45 |
|
395 |
|
|
/** |
396 |
|
|
* Key-value nodes for exception table. The chained hash table |
397 |
|
|
* uses identity comparisons, full locking, and weak references |
398 |
|
|
* for keys. The table has a fixed capacity because it only |
399 |
|
|
* maintains task exceptions long enough for joiners to access |
400 |
|
|
* them, so should never become very large for sustained |
401 |
|
|
* periods. However, since we do not know when the last joiner |
402 |
|
|
* completes, we must use weak references and expunge them. We do |
403 |
|
|
* so on each operation (hence full locking). Also, some thread in |
404 |
dl |
1.47 |
* any ForkJoinPool will call helpExpungeStaleExceptions when its |
405 |
|
|
* pool becomes isQuiescent. |
406 |
dl |
1.45 |
*/ |
407 |
jsr166 |
1.58 |
static final class ExceptionNode extends WeakReference<ForkJoinTask<?>> { |
408 |
dl |
1.45 |
final Throwable ex; |
409 |
|
|
ExceptionNode next; |
410 |
dl |
1.47 |
final long thrower; // use id not ref to avoid weak cycles |
411 |
dl |
1.85 |
final int hashCode; // store task hashCode before weak ref disappears |
412 |
jsr166 |
1.98 |
ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next, |
413 |
jsr166 |
1.112 |
ReferenceQueue<ForkJoinTask<?>> exceptionTableRefQueue) { |
414 |
dl |
1.45 |
super(task, exceptionTableRefQueue); |
415 |
|
|
this.ex = ex; |
416 |
|
|
this.next = next; |
417 |
|
|
this.thrower = Thread.currentThread().getId(); |
418 |
dl |
1.85 |
this.hashCode = System.identityHashCode(task); |
419 |
dl |
1.45 |
} |
420 |
|
|
} |
421 |
|
|
|
422 |
|
|
/** |
423 |
dl |
1.63 |
* Records exception and sets status. |
424 |
dl |
1.45 |
* |
425 |
|
|
* @return status on exit |
426 |
|
|
*/ |
427 |
dl |
1.63 |
final int recordExceptionalCompletion(Throwable ex) { |
428 |
dl |
1.62 |
int s; |
429 |
|
|
if ((s = status) >= 0) { |
430 |
|
|
int h = System.identityHashCode(this); |
431 |
|
|
final ReentrantLock lock = exceptionTableLock; |
432 |
|
|
lock.lock(); |
433 |
|
|
try { |
434 |
|
|
expungeStaleExceptions(); |
435 |
|
|
ExceptionNode[] t = exceptionTable; |
436 |
|
|
int i = h & (t.length - 1); |
437 |
|
|
for (ExceptionNode e = t[i]; ; e = e.next) { |
438 |
|
|
if (e == null) { |
439 |
jsr166 |
1.98 |
t[i] = new ExceptionNode(this, ex, t[i], |
440 |
|
|
exceptionTableRefQueue); |
441 |
dl |
1.62 |
break; |
442 |
|
|
} |
443 |
|
|
if (e.get() == this) // already present |
444 |
|
|
break; |
445 |
dl |
1.45 |
} |
446 |
dl |
1.62 |
} finally { |
447 |
|
|
lock.unlock(); |
448 |
dl |
1.45 |
} |
449 |
dl |
1.62 |
s = setCompletion(EXCEPTIONAL); |
450 |
dl |
1.45 |
} |
451 |
dl |
1.62 |
return s; |
452 |
|
|
} |
453 |
|
|
|
454 |
|
|
/** |
455 |
jsr166 |
1.70 |
* Records exception and possibly propagates. |
456 |
dl |
1.63 |
* |
457 |
|
|
* @return status on exit |
458 |
|
|
*/ |
459 |
|
|
private int setExceptionalCompletion(Throwable ex) { |
460 |
|
|
int s = recordExceptionalCompletion(ex); |
461 |
|
|
if ((s & DONE_MASK) == EXCEPTIONAL) |
462 |
|
|
internalPropagateException(ex); |
463 |
|
|
return s; |
464 |
|
|
} |
465 |
|
|
|
466 |
|
|
/** |
467 |
|
|
* Hook for exception propagation support for tasks with completers. |
468 |
dl |
1.62 |
*/ |
469 |
dl |
1.63 |
void internalPropagateException(Throwable ex) { |
470 |
dl |
1.45 |
} |
471 |
|
|
|
472 |
|
|
/** |
473 |
dl |
1.54 |
* Cancels, ignoring any exceptions thrown by cancel. Used during |
474 |
|
|
* worker and pool shutdown. Cancel is spec'ed not to throw any |
475 |
|
|
* exceptions, but if it does anyway, we have no recourse during |
476 |
|
|
* shutdown, so guard against this case. |
477 |
|
|
*/ |
478 |
|
|
static final void cancelIgnoringExceptions(ForkJoinTask<?> t) { |
479 |
|
|
if (t != null && t.status >= 0) { |
480 |
|
|
try { |
481 |
|
|
t.cancel(false); |
482 |
|
|
} catch (Throwable ignore) { |
483 |
|
|
} |
484 |
|
|
} |
485 |
|
|
} |
486 |
|
|
|
487 |
|
|
/** |
488 |
jsr166 |
1.72 |
* Removes exception node and clears status. |
489 |
dl |
1.45 |
*/ |
490 |
|
|
private void clearExceptionalCompletion() { |
491 |
|
|
int h = System.identityHashCode(this); |
492 |
dl |
1.47 |
final ReentrantLock lock = exceptionTableLock; |
493 |
dl |
1.45 |
lock.lock(); |
494 |
|
|
try { |
495 |
|
|
ExceptionNode[] t = exceptionTable; |
496 |
|
|
int i = h & (t.length - 1); |
497 |
|
|
ExceptionNode e = t[i]; |
498 |
|
|
ExceptionNode pred = null; |
499 |
|
|
while (e != null) { |
500 |
|
|
ExceptionNode next = e.next; |
501 |
|
|
if (e.get() == this) { |
502 |
|
|
if (pred == null) |
503 |
|
|
t[i] = next; |
504 |
|
|
else |
505 |
|
|
pred.next = next; |
506 |
|
|
break; |
507 |
|
|
} |
508 |
|
|
pred = e; |
509 |
|
|
e = next; |
510 |
|
|
} |
511 |
|
|
expungeStaleExceptions(); |
512 |
|
|
status = 0; |
513 |
|
|
} finally { |
514 |
|
|
lock.unlock(); |
515 |
|
|
} |
516 |
|
|
} |
517 |
|
|
|
518 |
|
|
/** |
519 |
jsr166 |
1.105 |
* Returns a rethrowable exception for this task, if available. |
520 |
|
|
* To provide accurate stack traces, if the exception was not |
521 |
|
|
* thrown by the current thread, we try to create a new exception |
522 |
|
|
* of the same type as the one thrown, but with the recorded |
523 |
|
|
* exception as its cause. If there is no such constructor, we |
524 |
|
|
* instead try to use a no-arg constructor, followed by initCause, |
525 |
|
|
* to the same effect. If none of these apply, or any fail due to |
526 |
|
|
* other exceptions, we return the recorded exception, which is |
527 |
|
|
* still correct, although it may contain a misleading stack |
528 |
|
|
* trace. |
529 |
dl |
1.45 |
* |
530 |
|
|
* @return the exception, or null if none |
531 |
|
|
*/ |
532 |
|
|
private Throwable getThrowableException() { |
533 |
|
|
int h = System.identityHashCode(this); |
534 |
|
|
ExceptionNode e; |
535 |
dl |
1.47 |
final ReentrantLock lock = exceptionTableLock; |
536 |
dl |
1.45 |
lock.lock(); |
537 |
|
|
try { |
538 |
|
|
expungeStaleExceptions(); |
539 |
|
|
ExceptionNode[] t = exceptionTable; |
540 |
|
|
e = t[h & (t.length - 1)]; |
541 |
|
|
while (e != null && e.get() != this) |
542 |
|
|
e = e.next; |
543 |
|
|
} finally { |
544 |
|
|
lock.unlock(); |
545 |
|
|
} |
546 |
|
|
Throwable ex; |
547 |
|
|
if (e == null || (ex = e.ex) == null) |
548 |
|
|
return null; |
549 |
dl |
1.86 |
if (e.thrower != Thread.currentThread().getId()) { |
550 |
dl |
1.45 |
try { |
551 |
|
|
Constructor<?> noArgCtor = null; |
552 |
jsr166 |
1.106 |
// public ctors only |
553 |
|
|
for (Constructor<?> c : ex.getClass().getConstructors()) { |
554 |
dl |
1.45 |
Class<?>[] ps = c.getParameterTypes(); |
555 |
|
|
if (ps.length == 0) |
556 |
|
|
noArgCtor = c; |
557 |
jsr166 |
1.106 |
else if (ps.length == 1 && ps[0] == Throwable.class) |
558 |
|
|
return (Throwable)c.newInstance(ex); |
559 |
dl |
1.45 |
} |
560 |
|
|
if (noArgCtor != null) { |
561 |
jsr166 |
1.106 |
Throwable wx = (Throwable)noArgCtor.newInstance(); |
562 |
|
|
wx.initCause(ex); |
563 |
|
|
return wx; |
564 |
dl |
1.45 |
} |
565 |
|
|
} catch (Exception ignore) { |
566 |
|
|
} |
567 |
|
|
} |
568 |
|
|
return ex; |
569 |
|
|
} |
570 |
|
|
|
571 |
|
|
/** |
572 |
jsr166 |
1.101 |
* Polls stale refs and removes them. Call only while holding lock. |
573 |
dl |
1.45 |
*/ |
574 |
|
|
private static void expungeStaleExceptions() { |
575 |
|
|
for (Object x; (x = exceptionTableRefQueue.poll()) != null;) { |
576 |
|
|
if (x instanceof ExceptionNode) { |
577 |
|
|
ExceptionNode[] t = exceptionTable; |
578 |
jsr166 |
1.111 |
int i = ((ExceptionNode)x).hashCode & (t.length - 1); |
579 |
dl |
1.45 |
ExceptionNode e = t[i]; |
580 |
|
|
ExceptionNode pred = null; |
581 |
|
|
while (e != null) { |
582 |
|
|
ExceptionNode next = e.next; |
583 |
|
|
if (e == x) { |
584 |
|
|
if (pred == null) |
585 |
|
|
t[i] = next; |
586 |
|
|
else |
587 |
|
|
pred.next = next; |
588 |
|
|
break; |
589 |
|
|
} |
590 |
|
|
pred = e; |
591 |
|
|
e = next; |
592 |
|
|
} |
593 |
|
|
} |
594 |
|
|
} |
595 |
|
|
} |
596 |
|
|
|
597 |
|
|
/** |
598 |
jsr166 |
1.101 |
* If lock is available, polls stale refs and removes them. |
599 |
dl |
1.45 |
* Called from ForkJoinPool when pools become quiescent. |
600 |
|
|
*/ |
601 |
|
|
static final void helpExpungeStaleExceptions() { |
602 |
dl |
1.47 |
final ReentrantLock lock = exceptionTableLock; |
603 |
dl |
1.45 |
if (lock.tryLock()) { |
604 |
|
|
try { |
605 |
|
|
expungeStaleExceptions(); |
606 |
|
|
} finally { |
607 |
|
|
lock.unlock(); |
608 |
|
|
} |
609 |
jsr166 |
1.1 |
} |
610 |
dl |
1.45 |
} |
611 |
|
|
|
612 |
|
|
/** |
613 |
jsr166 |
1.99 |
* A version of "sneaky throw" to relay exceptions. |
614 |
dl |
1.65 |
*/ |
615 |
jsr166 |
1.78 |
static void rethrow(Throwable ex) { |
616 |
dl |
1.100 |
ForkJoinTask.<RuntimeException>uncheckedThrow(ex); |
617 |
dl |
1.65 |
} |
618 |
|
|
|
619 |
|
|
/** |
620 |
|
|
* The sneaky part of sneaky throw, relying on generics |
621 |
|
|
* limitations to evade compiler complaints about rethrowing |
622 |
jsr166 |
1.99 |
* unchecked exceptions. |
623 |
dl |
1.65 |
*/ |
624 |
|
|
@SuppressWarnings("unchecked") static <T extends Throwable> |
625 |
dl |
1.100 |
void uncheckedThrow(Throwable t) throws T { |
626 |
|
|
if (t != null) |
627 |
|
|
throw (T)t; // rely on vacuous cast |
628 |
|
|
else |
629 |
|
|
throw new Error("Unknown Exception"); |
630 |
dl |
1.65 |
} |
631 |
|
|
|
632 |
|
|
/** |
633 |
dl |
1.59 |
* Throws exception, if any, associated with the given status. |
634 |
dl |
1.45 |
*/ |
635 |
dl |
1.59 |
private void reportException(int s) { |
636 |
dl |
1.65 |
if (s == CANCELLED) |
637 |
|
|
throw new CancellationException(); |
638 |
|
|
if (s == EXCEPTIONAL) |
639 |
|
|
rethrow(getThrowableException()); |
640 |
jsr166 |
1.1 |
} |
641 |
|
|
|
642 |
|
|
// public methods |
643 |
|
|
|
644 |
|
|
/** |
645 |
dl |
1.64 |
* Arranges to asynchronously execute this task in the pool the |
646 |
|
|
* current task is running in, if applicable, or using the {@link |
647 |
dl |
1.67 |
* ForkJoinPool#commonPool()} if not {@link #inForkJoinPool}. While |
648 |
dl |
1.64 |
* it is not necessarily enforced, it is a usage error to fork a |
649 |
|
|
* task more than once unless it has completed and been |
650 |
|
|
* reinitialized. Subsequent modifications to the state of this |
651 |
|
|
* task or any data it operates on are not necessarily |
652 |
|
|
* consistently observable by any thread other than the one |
653 |
|
|
* executing it unless preceded by a call to {@link #join} or |
654 |
|
|
* related methods, or a call to {@link #isDone} returning {@code |
655 |
|
|
* true}. |
656 |
jsr166 |
1.2 |
* |
657 |
jsr166 |
1.6 |
* @return {@code this}, to simplify usage |
658 |
jsr166 |
1.1 |
*/ |
659 |
jsr166 |
1.2 |
public final ForkJoinTask<V> fork() { |
660 |
dl |
1.64 |
Thread t; |
661 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
662 |
|
|
((ForkJoinWorkerThread)t).workQueue.push(this); |
663 |
|
|
else |
664 |
dl |
1.71 |
ForkJoinPool.common.externalPush(this); |
665 |
jsr166 |
1.2 |
return this; |
666 |
jsr166 |
1.1 |
} |
667 |
|
|
|
668 |
|
|
/** |
669 |
jsr166 |
1.115 |
* Returns the result of the computation when it |
670 |
|
|
* {@linkplain #isDone is done}. |
671 |
|
|
* This method differs from {@link #get()} in that abnormal |
672 |
|
|
* completion results in {@code RuntimeException} or {@code Error}, |
673 |
|
|
* not {@code ExecutionException}, and that interrupts of the |
674 |
|
|
* calling thread do <em>not</em> cause the method to abruptly |
675 |
|
|
* return by throwing {@code InterruptedException}. |
676 |
jsr166 |
1.1 |
* |
677 |
|
|
* @return the computed result |
678 |
|
|
*/ |
679 |
|
|
public final V join() { |
680 |
dl |
1.59 |
int s; |
681 |
|
|
if ((s = doJoin() & DONE_MASK) != NORMAL) |
682 |
|
|
reportException(s); |
683 |
|
|
return getRawResult(); |
684 |
jsr166 |
1.1 |
} |
685 |
|
|
|
686 |
|
|
/** |
687 |
|
|
* Commences performing this task, awaits its completion if |
688 |
jsr166 |
1.21 |
* necessary, and returns its result, or throws an (unchecked) |
689 |
dl |
1.20 |
* {@code RuntimeException} or {@code Error} if the underlying |
690 |
|
|
* computation did so. |
691 |
jsr166 |
1.1 |
* |
692 |
|
|
* @return the computed result |
693 |
|
|
*/ |
694 |
|
|
public final V invoke() { |
695 |
dl |
1.59 |
int s; |
696 |
|
|
if ((s = doInvoke() & DONE_MASK) != NORMAL) |
697 |
|
|
reportException(s); |
698 |
|
|
return getRawResult(); |
699 |
jsr166 |
1.1 |
} |
700 |
|
|
|
701 |
|
|
/** |
702 |
jsr166 |
1.8 |
* Forks the given tasks, returning when {@code isDone} holds for |
703 |
|
|
* each task or an (unchecked) exception is encountered, in which |
704 |
dl |
1.20 |
* case the exception is rethrown. If more than one task |
705 |
|
|
* encounters an exception, then this method throws any one of |
706 |
|
|
* these exceptions. If any task encounters an exception, the |
707 |
|
|
* other may be cancelled. However, the execution status of |
708 |
|
|
* individual tasks is not guaranteed upon exceptional return. The |
709 |
|
|
* status of each task may be obtained using {@link |
710 |
|
|
* #getException()} and related methods to check if they have been |
711 |
|
|
* cancelled, completed normally or exceptionally, or left |
712 |
|
|
* unprocessed. |
713 |
jsr166 |
1.6 |
* |
714 |
|
|
* @param t1 the first task |
715 |
|
|
* @param t2 the second task |
716 |
|
|
* @throws NullPointerException if any task is null |
717 |
jsr166 |
1.1 |
*/ |
718 |
jsr166 |
1.6 |
public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) { |
719 |
dl |
1.59 |
int s1, s2; |
720 |
jsr166 |
1.1 |
t2.fork(); |
721 |
dl |
1.59 |
if ((s1 = t1.doInvoke() & DONE_MASK) != NORMAL) |
722 |
|
|
t1.reportException(s1); |
723 |
|
|
if ((s2 = t2.doJoin() & DONE_MASK) != NORMAL) |
724 |
|
|
t2.reportException(s2); |
725 |
jsr166 |
1.1 |
} |
726 |
|
|
|
727 |
|
|
/** |
728 |
jsr166 |
1.6 |
* Forks the given tasks, returning when {@code isDone} holds for |
729 |
jsr166 |
1.8 |
* each task or an (unchecked) exception is encountered, in which |
730 |
dl |
1.20 |
* case the exception is rethrown. If more than one task |
731 |
|
|
* encounters an exception, then this method throws any one of |
732 |
|
|
* these exceptions. If any task encounters an exception, others |
733 |
|
|
* may be cancelled. However, the execution status of individual |
734 |
|
|
* tasks is not guaranteed upon exceptional return. The status of |
735 |
|
|
* each task may be obtained using {@link #getException()} and |
736 |
|
|
* related methods to check if they have been cancelled, completed |
737 |
|
|
* normally or exceptionally, or left unprocessed. |
738 |
jsr166 |
1.6 |
* |
739 |
|
|
* @param tasks the tasks |
740 |
jsr166 |
1.8 |
* @throws NullPointerException if any task is null |
741 |
jsr166 |
1.1 |
*/ |
742 |
|
|
public static void invokeAll(ForkJoinTask<?>... tasks) { |
743 |
|
|
Throwable ex = null; |
744 |
|
|
int last = tasks.length - 1; |
745 |
|
|
for (int i = last; i >= 0; --i) { |
746 |
|
|
ForkJoinTask<?> t = tasks[i]; |
747 |
|
|
if (t == null) { |
748 |
|
|
if (ex == null) |
749 |
|
|
ex = new NullPointerException(); |
750 |
|
|
} |
751 |
|
|
else if (i != 0) |
752 |
|
|
t.fork(); |
753 |
dl |
1.45 |
else if (t.doInvoke() < NORMAL && ex == null) |
754 |
|
|
ex = t.getException(); |
755 |
jsr166 |
1.1 |
} |
756 |
|
|
for (int i = 1; i <= last; ++i) { |
757 |
|
|
ForkJoinTask<?> t = tasks[i]; |
758 |
|
|
if (t != null) { |
759 |
|
|
if (ex != null) |
760 |
|
|
t.cancel(false); |
761 |
jsr166 |
1.52 |
else if (t.doJoin() < NORMAL) |
762 |
dl |
1.45 |
ex = t.getException(); |
763 |
jsr166 |
1.1 |
} |
764 |
|
|
} |
765 |
|
|
if (ex != null) |
766 |
dl |
1.65 |
rethrow(ex); |
767 |
jsr166 |
1.1 |
} |
768 |
|
|
|
769 |
|
|
/** |
770 |
jsr166 |
1.7 |
* Forks all tasks in the specified collection, returning when |
771 |
jsr166 |
1.8 |
* {@code isDone} holds for each task or an (unchecked) exception |
772 |
dl |
1.20 |
* is encountered, in which case the exception is rethrown. If |
773 |
|
|
* more than one task encounters an exception, then this method |
774 |
|
|
* throws any one of these exceptions. If any task encounters an |
775 |
|
|
* exception, others may be cancelled. However, the execution |
776 |
|
|
* status of individual tasks is not guaranteed upon exceptional |
777 |
|
|
* return. The status of each task may be obtained using {@link |
778 |
|
|
* #getException()} and related methods to check if they have been |
779 |
|
|
* cancelled, completed normally or exceptionally, or left |
780 |
|
|
* unprocessed. |
781 |
jsr166 |
1.6 |
* |
782 |
jsr166 |
1.1 |
* @param tasks the collection of tasks |
783 |
jsr166 |
1.82 |
* @param <T> the type of the values returned from the tasks |
784 |
jsr166 |
1.2 |
* @return the tasks argument, to simplify usage |
785 |
jsr166 |
1.1 |
* @throws NullPointerException if tasks or any element are null |
786 |
|
|
*/ |
787 |
jsr166 |
1.2 |
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
788 |
jsr166 |
1.7 |
if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) { |
789 |
jsr166 |
1.1 |
invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()])); |
790 |
jsr166 |
1.2 |
return tasks; |
791 |
jsr166 |
1.1 |
} |
792 |
|
|
@SuppressWarnings("unchecked") |
793 |
|
|
List<? extends ForkJoinTask<?>> ts = |
794 |
|
|
(List<? extends ForkJoinTask<?>>) tasks; |
795 |
|
|
Throwable ex = null; |
796 |
|
|
int last = ts.size() - 1; |
797 |
|
|
for (int i = last; i >= 0; --i) { |
798 |
|
|
ForkJoinTask<?> t = ts.get(i); |
799 |
|
|
if (t == null) { |
800 |
|
|
if (ex == null) |
801 |
|
|
ex = new NullPointerException(); |
802 |
|
|
} |
803 |
|
|
else if (i != 0) |
804 |
|
|
t.fork(); |
805 |
dl |
1.45 |
else if (t.doInvoke() < NORMAL && ex == null) |
806 |
|
|
ex = t.getException(); |
807 |
jsr166 |
1.1 |
} |
808 |
|
|
for (int i = 1; i <= last; ++i) { |
809 |
|
|
ForkJoinTask<?> t = ts.get(i); |
810 |
|
|
if (t != null) { |
811 |
|
|
if (ex != null) |
812 |
|
|
t.cancel(false); |
813 |
jsr166 |
1.52 |
else if (t.doJoin() < NORMAL) |
814 |
dl |
1.45 |
ex = t.getException(); |
815 |
jsr166 |
1.1 |
} |
816 |
|
|
} |
817 |
|
|
if (ex != null) |
818 |
dl |
1.65 |
rethrow(ex); |
819 |
jsr166 |
1.2 |
return tasks; |
820 |
jsr166 |
1.1 |
} |
821 |
|
|
|
822 |
|
|
/** |
823 |
jsr166 |
1.7 |
* Attempts to cancel execution of this task. This attempt will |
824 |
jsr166 |
1.36 |
* fail if the task has already completed or could not be |
825 |
|
|
* cancelled for some other reason. If successful, and this task |
826 |
|
|
* has not started when {@code cancel} is called, execution of |
827 |
dl |
1.38 |
* this task is suppressed. After this method returns |
828 |
|
|
* successfully, unless there is an intervening call to {@link |
829 |
|
|
* #reinitialize}, subsequent calls to {@link #isCancelled}, |
830 |
|
|
* {@link #isDone}, and {@code cancel} will return {@code true} |
831 |
|
|
* and calls to {@link #join} and related methods will result in |
832 |
|
|
* {@code CancellationException}. |
833 |
jsr166 |
1.1 |
* |
834 |
|
|
* <p>This method may be overridden in subclasses, but if so, must |
835 |
dl |
1.38 |
* still ensure that these properties hold. In particular, the |
836 |
|
|
* {@code cancel} method itself must not throw exceptions. |
837 |
jsr166 |
1.1 |
* |
838 |
jsr166 |
1.6 |
* <p>This method is designed to be invoked by <em>other</em> |
839 |
jsr166 |
1.1 |
* tasks. To terminate the current task, you can just return or |
840 |
|
|
* throw an unchecked exception from its computation method, or |
841 |
jsr166 |
1.74 |
* invoke {@link #completeExceptionally(Throwable)}. |
842 |
jsr166 |
1.1 |
* |
843 |
dl |
1.38 |
* @param mayInterruptIfRunning this value has no effect in the |
844 |
|
|
* default implementation because interrupts are not used to |
845 |
|
|
* control cancellation. |
846 |
jsr166 |
1.1 |
* |
847 |
jsr166 |
1.4 |
* @return {@code true} if this task is now cancelled |
848 |
jsr166 |
1.1 |
*/ |
849 |
|
|
public boolean cancel(boolean mayInterruptIfRunning) { |
850 |
dl |
1.59 |
return (setCompletion(CANCELLED) & DONE_MASK) == CANCELLED; |
851 |
jsr166 |
1.1 |
} |
852 |
|
|
|
853 |
jsr166 |
1.8 |
public final boolean isDone() { |
854 |
|
|
return status < 0; |
855 |
|
|
} |
856 |
|
|
|
857 |
|
|
public final boolean isCancelled() { |
858 |
dl |
1.59 |
return (status & DONE_MASK) == CANCELLED; |
859 |
jsr166 |
1.8 |
} |
860 |
|
|
|
861 |
|
|
/** |
862 |
jsr166 |
1.4 |
* Returns {@code true} if this task threw an exception or was cancelled. |
863 |
jsr166 |
1.1 |
* |
864 |
jsr166 |
1.4 |
* @return {@code true} if this task threw an exception or was cancelled |
865 |
jsr166 |
1.1 |
*/ |
866 |
|
|
public final boolean isCompletedAbnormally() { |
867 |
dl |
1.16 |
return status < NORMAL; |
868 |
jsr166 |
1.1 |
} |
869 |
|
|
|
870 |
|
|
/** |
871 |
jsr166 |
1.8 |
* Returns {@code true} if this task completed without throwing an |
872 |
|
|
* exception and was not cancelled. |
873 |
|
|
* |
874 |
|
|
* @return {@code true} if this task completed without throwing an |
875 |
|
|
* exception and was not cancelled |
876 |
|
|
*/ |
877 |
|
|
public final boolean isCompletedNormally() { |
878 |
dl |
1.59 |
return (status & DONE_MASK) == NORMAL; |
879 |
jsr166 |
1.8 |
} |
880 |
|
|
|
881 |
|
|
/** |
882 |
jsr166 |
1.1 |
* Returns the exception thrown by the base computation, or a |
883 |
jsr166 |
1.6 |
* {@code CancellationException} if cancelled, or {@code null} if |
884 |
|
|
* none or if the method has not yet completed. |
885 |
jsr166 |
1.1 |
* |
886 |
jsr166 |
1.4 |
* @return the exception, or {@code null} if none |
887 |
jsr166 |
1.1 |
*/ |
888 |
|
|
public final Throwable getException() { |
889 |
dl |
1.59 |
int s = status & DONE_MASK; |
890 |
jsr166 |
1.8 |
return ((s >= NORMAL) ? null : |
891 |
|
|
(s == CANCELLED) ? new CancellationException() : |
892 |
dl |
1.45 |
getThrowableException()); |
893 |
jsr166 |
1.1 |
} |
894 |
|
|
|
895 |
|
|
/** |
896 |
|
|
* Completes this task abnormally, and if not already aborted or |
897 |
|
|
* cancelled, causes it to throw the given exception upon |
898 |
|
|
* {@code join} and related operations. This method may be used |
899 |
|
|
* to induce exceptions in asynchronous tasks, or to force |
900 |
|
|
* completion of tasks that would not otherwise complete. Its use |
901 |
jsr166 |
1.6 |
* in other situations is discouraged. This method is |
902 |
jsr166 |
1.1 |
* overridable, but overridden versions must invoke {@code super} |
903 |
|
|
* implementation to maintain guarantees. |
904 |
|
|
* |
905 |
jsr166 |
1.11 |
* @param ex the exception to throw. If this exception is not a |
906 |
|
|
* {@code RuntimeException} or {@code Error}, the actual exception |
907 |
|
|
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
908 |
jsr166 |
1.1 |
*/ |
909 |
|
|
public void completeExceptionally(Throwable ex) { |
910 |
dl |
1.15 |
setExceptionalCompletion((ex instanceof RuntimeException) || |
911 |
|
|
(ex instanceof Error) ? ex : |
912 |
|
|
new RuntimeException(ex)); |
913 |
jsr166 |
1.1 |
} |
914 |
|
|
|
915 |
|
|
/** |
916 |
|
|
* Completes this task, and if not already aborted or cancelled, |
917 |
dl |
1.22 |
* returning the given value as the result of subsequent |
918 |
|
|
* invocations of {@code join} and related operations. This method |
919 |
|
|
* may be used to provide results for asynchronous tasks, or to |
920 |
|
|
* provide alternative handling for tasks that would not otherwise |
921 |
|
|
* complete normally. Its use in other situations is |
922 |
|
|
* discouraged. This method is overridable, but overridden |
923 |
|
|
* versions must invoke {@code super} implementation to maintain |
924 |
|
|
* guarantees. |
925 |
jsr166 |
1.1 |
* |
926 |
|
|
* @param value the result value for this task |
927 |
|
|
*/ |
928 |
|
|
public void complete(V value) { |
929 |
|
|
try { |
930 |
|
|
setRawResult(value); |
931 |
|
|
} catch (Throwable rex) { |
932 |
dl |
1.15 |
setExceptionalCompletion(rex); |
933 |
jsr166 |
1.1 |
return; |
934 |
|
|
} |
935 |
dl |
1.13 |
setCompletion(NORMAL); |
936 |
jsr166 |
1.1 |
} |
937 |
|
|
|
938 |
jsr166 |
1.25 |
/** |
939 |
dl |
1.62 |
* Completes this task normally without setting a value. The most |
940 |
|
|
* recent value established by {@link #setRawResult} (or {@code |
941 |
|
|
* null} by default) will be returned as the result of subsequent |
942 |
|
|
* invocations of {@code join} and related operations. |
943 |
|
|
* |
944 |
|
|
* @since 1.8 |
945 |
dl |
1.60 |
*/ |
946 |
|
|
public final void quietlyComplete() { |
947 |
|
|
setCompletion(NORMAL); |
948 |
|
|
} |
949 |
|
|
|
950 |
|
|
/** |
951 |
dl |
1.29 |
* Waits if necessary for the computation to complete, and then |
952 |
|
|
* retrieves its result. |
953 |
|
|
* |
954 |
|
|
* @return the computed result |
955 |
|
|
* @throws CancellationException if the computation was cancelled |
956 |
|
|
* @throws ExecutionException if the computation threw an |
957 |
|
|
* exception |
958 |
|
|
* @throws InterruptedException if the current thread is not a |
959 |
|
|
* member of a ForkJoinPool and was interrupted while waiting |
960 |
jsr166 |
1.25 |
*/ |
961 |
jsr166 |
1.1 |
public final V get() throws InterruptedException, ExecutionException { |
962 |
dl |
1.45 |
int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ? |
963 |
dl |
1.59 |
doJoin() : externalInterruptibleAwaitDone(); |
964 |
|
|
if ((s &= DONE_MASK) == CANCELLED) |
965 |
dl |
1.45 |
throw new CancellationException(); |
966 |
dl |
1.100 |
if (s == EXCEPTIONAL) |
967 |
|
|
throw new ExecutionException(getThrowableException()); |
968 |
dl |
1.15 |
return getRawResult(); |
969 |
jsr166 |
1.1 |
} |
970 |
dl |
1.14 |
|
971 |
jsr166 |
1.25 |
/** |
972 |
dl |
1.29 |
* Waits if necessary for at most the given time for the computation |
973 |
|
|
* to complete, and then retrieves its result, if available. |
974 |
|
|
* |
975 |
|
|
* @param timeout the maximum time to wait |
976 |
|
|
* @param unit the time unit of the timeout argument |
977 |
|
|
* @return the computed result |
978 |
|
|
* @throws CancellationException if the computation was cancelled |
979 |
|
|
* @throws ExecutionException if the computation threw an |
980 |
|
|
* exception |
981 |
|
|
* @throws InterruptedException if the current thread is not a |
982 |
|
|
* member of a ForkJoinPool and was interrupted while waiting |
983 |
|
|
* @throws TimeoutException if the wait timed out |
984 |
jsr166 |
1.25 |
*/ |
985 |
jsr166 |
1.1 |
public final V get(long timeout, TimeUnit unit) |
986 |
|
|
throws InterruptedException, ExecutionException, TimeoutException { |
987 |
dl |
1.87 |
int s; |
988 |
|
|
long nanos = unit.toNanos(timeout); |
989 |
dl |
1.59 |
if (Thread.interrupted()) |
990 |
|
|
throw new InterruptedException(); |
991 |
dl |
1.87 |
if ((s = status) >= 0 && nanos > 0L) { |
992 |
|
|
long d = System.nanoTime() + nanos; |
993 |
jsr166 |
1.88 |
long deadline = (d == 0L) ? 1L : d; // avoid 0 |
994 |
dl |
1.59 |
Thread t = Thread.currentThread(); |
995 |
|
|
if (t instanceof ForkJoinWorkerThread) { |
996 |
|
|
ForkJoinWorkerThread wt = (ForkJoinWorkerThread)t; |
997 |
dl |
1.87 |
s = wt.pool.awaitJoin(wt.workQueue, this, deadline); |
998 |
dl |
1.59 |
} |
999 |
dl |
1.87 |
else if ((s = ((this instanceof CountedCompleter) ? |
1000 |
|
|
ForkJoinPool.common.externalHelpComplete( |
1001 |
|
|
(CountedCompleter<?>)this, 0) : |
1002 |
|
|
ForkJoinPool.common.tryExternalUnpush(this) ? |
1003 |
|
|
doExec() : 0)) >= 0) { |
1004 |
|
|
long ns, ms; // measure in nanosecs, but wait in millisecs |
1005 |
|
|
while ((s = status) >= 0 && |
1006 |
|
|
(ns = deadline - System.nanoTime()) > 0L) { |
1007 |
|
|
if ((ms = TimeUnit.NANOSECONDS.toMillis(ns)) > 0L && |
1008 |
dl |
1.109 |
STATUS.compareAndSet(this, s, s | SIGNAL)) { |
1009 |
dl |
1.87 |
synchronized (this) { |
1010 |
|
|
if (status >= 0) |
1011 |
|
|
wait(ms); // OK to throw InterruptedException |
1012 |
|
|
else |
1013 |
|
|
notifyAll(); |
1014 |
dl |
1.54 |
} |
1015 |
dl |
1.45 |
} |
1016 |
|
|
} |
1017 |
|
|
} |
1018 |
|
|
} |
1019 |
dl |
1.87 |
if (s >= 0) |
1020 |
|
|
s = status; |
1021 |
dl |
1.59 |
if ((s &= DONE_MASK) != NORMAL) { |
1022 |
dl |
1.40 |
if (s == CANCELLED) |
1023 |
dl |
1.15 |
throw new CancellationException(); |
1024 |
dl |
1.45 |
if (s != EXCEPTIONAL) |
1025 |
|
|
throw new TimeoutException(); |
1026 |
dl |
1.100 |
throw new ExecutionException(getThrowableException()); |
1027 |
dl |
1.15 |
} |
1028 |
|
|
return getRawResult(); |
1029 |
jsr166 |
1.1 |
} |
1030 |
|
|
|
1031 |
|
|
/** |
1032 |
dl |
1.17 |
* Joins this task, without returning its result or throwing its |
1033 |
jsr166 |
1.1 |
* exception. This method may be useful when processing |
1034 |
|
|
* collections of tasks when some have been cancelled or otherwise |
1035 |
|
|
* known to have aborted. |
1036 |
|
|
*/ |
1037 |
|
|
public final void quietlyJoin() { |
1038 |
dl |
1.45 |
doJoin(); |
1039 |
jsr166 |
1.1 |
} |
1040 |
|
|
|
1041 |
|
|
/** |
1042 |
|
|
* Commences performing this task and awaits its completion if |
1043 |
dl |
1.17 |
* necessary, without returning its result or throwing its |
1044 |
dl |
1.22 |
* exception. |
1045 |
jsr166 |
1.1 |
*/ |
1046 |
|
|
public final void quietlyInvoke() { |
1047 |
dl |
1.45 |
doInvoke(); |
1048 |
jsr166 |
1.1 |
} |
1049 |
|
|
|
1050 |
|
|
/** |
1051 |
|
|
* Possibly executes tasks until the pool hosting the current task |
1052 |
jsr166 |
1.104 |
* {@linkplain ForkJoinPool#isQuiescent is quiescent}. This |
1053 |
|
|
* method may be of use in designs in which many tasks are forked, |
1054 |
|
|
* but none are explicitly joined, instead executing them until |
1055 |
|
|
* all are processed. |
1056 |
jsr166 |
1.1 |
*/ |
1057 |
|
|
public static void helpQuiesce() { |
1058 |
dl |
1.64 |
Thread t; |
1059 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) { |
1060 |
|
|
ForkJoinWorkerThread wt = (ForkJoinWorkerThread)t; |
1061 |
|
|
wt.pool.helpQuiescePool(wt.workQueue); |
1062 |
|
|
} |
1063 |
|
|
else |
1064 |
dl |
1.71 |
ForkJoinPool.quiesceCommonPool(); |
1065 |
jsr166 |
1.1 |
} |
1066 |
|
|
|
1067 |
|
|
/** |
1068 |
|
|
* Resets the internal bookkeeping state of this task, allowing a |
1069 |
|
|
* subsequent {@code fork}. This method allows repeated reuse of |
1070 |
|
|
* this task, but only if reuse occurs when this task has either |
1071 |
|
|
* never been forked, or has been forked, then completed and all |
1072 |
|
|
* outstanding joins of this task have also completed. Effects |
1073 |
jsr166 |
1.6 |
* under any other usage conditions are not guaranteed. |
1074 |
|
|
* This method may be useful when executing |
1075 |
jsr166 |
1.1 |
* pre-constructed trees of subtasks in loops. |
1076 |
jsr166 |
1.34 |
* |
1077 |
dl |
1.33 |
* <p>Upon completion of this method, {@code isDone()} reports |
1078 |
|
|
* {@code false}, and {@code getException()} reports {@code |
1079 |
|
|
* null}. However, the value returned by {@code getRawResult} is |
1080 |
|
|
* unaffected. To clear this value, you can invoke {@code |
1081 |
|
|
* setRawResult(null)}. |
1082 |
jsr166 |
1.1 |
*/ |
1083 |
|
|
public void reinitialize() { |
1084 |
dl |
1.59 |
if ((status & DONE_MASK) == EXCEPTIONAL) |
1085 |
dl |
1.45 |
clearExceptionalCompletion(); |
1086 |
|
|
else |
1087 |
|
|
status = 0; |
1088 |
jsr166 |
1.1 |
} |
1089 |
|
|
|
1090 |
|
|
/** |
1091 |
jsr166 |
1.103 |
* Returns the pool hosting the current thread, or {@code null} |
1092 |
|
|
* if the current thread is executing outside of any ForkJoinPool. |
1093 |
|
|
* |
1094 |
|
|
* <p>This method returns {@code null} if and only if {@link |
1095 |
|
|
* #inForkJoinPool} returns {@code false}. |
1096 |
jsr166 |
1.1 |
* |
1097 |
jsr166 |
1.97 |
* @return the pool, or {@code null} if none |
1098 |
jsr166 |
1.1 |
*/ |
1099 |
|
|
public static ForkJoinPool getPool() { |
1100 |
|
|
Thread t = Thread.currentThread(); |
1101 |
|
|
return (t instanceof ForkJoinWorkerThread) ? |
1102 |
|
|
((ForkJoinWorkerThread) t).pool : null; |
1103 |
|
|
} |
1104 |
|
|
|
1105 |
|
|
/** |
1106 |
dl |
1.42 |
* Returns {@code true} if the current thread is a {@link |
1107 |
|
|
* ForkJoinWorkerThread} executing as a ForkJoinPool computation. |
1108 |
jsr166 |
1.1 |
* |
1109 |
dl |
1.42 |
* @return {@code true} if the current thread is a {@link |
1110 |
|
|
* ForkJoinWorkerThread} executing as a ForkJoinPool computation, |
1111 |
|
|
* or {@code false} otherwise |
1112 |
jsr166 |
1.1 |
*/ |
1113 |
|
|
public static boolean inForkJoinPool() { |
1114 |
|
|
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
1115 |
|
|
} |
1116 |
|
|
|
1117 |
|
|
/** |
1118 |
|
|
* Tries to unschedule this task for execution. This method will |
1119 |
dl |
1.64 |
* typically (but is not guaranteed to) succeed if this task is |
1120 |
|
|
* the most recently forked task by the current thread, and has |
1121 |
|
|
* not commenced executing in another thread. This method may be |
1122 |
|
|
* useful when arranging alternative local processing of tasks |
1123 |
|
|
* that could have been, but were not, stolen. |
1124 |
jsr166 |
1.1 |
* |
1125 |
jsr166 |
1.4 |
* @return {@code true} if unforked |
1126 |
jsr166 |
1.1 |
*/ |
1127 |
|
|
public boolean tryUnfork() { |
1128 |
dl |
1.64 |
Thread t; |
1129 |
dl |
1.66 |
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1130 |
|
|
((ForkJoinWorkerThread)t).workQueue.tryUnpush(this) : |
1131 |
dl |
1.75 |
ForkJoinPool.common.tryExternalUnpush(this)); |
1132 |
jsr166 |
1.1 |
} |
1133 |
|
|
|
1134 |
|
|
/** |
1135 |
|
|
* Returns an estimate of the number of tasks that have been |
1136 |
|
|
* forked by the current worker thread but not yet executed. This |
1137 |
|
|
* value may be useful for heuristic decisions about whether to |
1138 |
|
|
* fork other tasks. |
1139 |
|
|
* |
1140 |
|
|
* @return the number of tasks |
1141 |
|
|
*/ |
1142 |
|
|
public static int getQueuedTaskCount() { |
1143 |
dl |
1.66 |
Thread t; ForkJoinPool.WorkQueue q; |
1144 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
1145 |
|
|
q = ((ForkJoinWorkerThread)t).workQueue; |
1146 |
|
|
else |
1147 |
|
|
q = ForkJoinPool.commonSubmitterQueue(); |
1148 |
|
|
return (q == null) ? 0 : q.queueSize(); |
1149 |
jsr166 |
1.1 |
} |
1150 |
|
|
|
1151 |
|
|
/** |
1152 |
|
|
* Returns an estimate of how many more locally queued tasks are |
1153 |
|
|
* held by the current worker thread than there are other worker |
1154 |
dl |
1.64 |
* threads that might steal them, or zero if this thread is not |
1155 |
|
|
* operating in a ForkJoinPool. This value may be useful for |
1156 |
jsr166 |
1.1 |
* heuristic decisions about whether to fork other tasks. In many |
1157 |
|
|
* usages of ForkJoinTasks, at steady state, each worker should |
1158 |
|
|
* aim to maintain a small constant surplus (for example, 3) of |
1159 |
|
|
* tasks, and to process computations locally if this threshold is |
1160 |
|
|
* exceeded. |
1161 |
|
|
* |
1162 |
|
|
* @return the surplus number of tasks, which may be negative |
1163 |
|
|
*/ |
1164 |
|
|
public static int getSurplusQueuedTaskCount() { |
1165 |
dl |
1.66 |
return ForkJoinPool.getSurplusQueuedTaskCount(); |
1166 |
jsr166 |
1.1 |
} |
1167 |
|
|
|
1168 |
|
|
// Extension methods |
1169 |
|
|
|
1170 |
|
|
/** |
1171 |
jsr166 |
1.4 |
* Returns the result that would be returned by {@link #join}, even |
1172 |
|
|
* if this task completed abnormally, or {@code null} if this task |
1173 |
|
|
* is not known to have been completed. This method is designed |
1174 |
|
|
* to aid debugging, as well as to support extensions. Its use in |
1175 |
|
|
* any other context is discouraged. |
1176 |
jsr166 |
1.1 |
* |
1177 |
jsr166 |
1.4 |
* @return the result, or {@code null} if not completed |
1178 |
jsr166 |
1.1 |
*/ |
1179 |
|
|
public abstract V getRawResult(); |
1180 |
|
|
|
1181 |
|
|
/** |
1182 |
|
|
* Forces the given value to be returned as a result. This method |
1183 |
|
|
* is designed to support extensions, and should not in general be |
1184 |
|
|
* called otherwise. |
1185 |
|
|
* |
1186 |
|
|
* @param value the value |
1187 |
|
|
*/ |
1188 |
|
|
protected abstract void setRawResult(V value); |
1189 |
|
|
|
1190 |
|
|
/** |
1191 |
dl |
1.62 |
* Immediately performs the base action of this task and returns |
1192 |
|
|
* true if, upon return from this method, this task is guaranteed |
1193 |
|
|
* to have completed normally. This method may return false |
1194 |
|
|
* otherwise, to indicate that this task is not necessarily |
1195 |
|
|
* complete (or is not known to be complete), for example in |
1196 |
jsr166 |
1.1 |
* asynchronous actions that require explicit invocations of |
1197 |
dl |
1.62 |
* completion methods. This method may also throw an (unchecked) |
1198 |
|
|
* exception to indicate abnormal exit. This method is designed to |
1199 |
|
|
* support extensions, and should not in general be called |
1200 |
|
|
* otherwise. |
1201 |
jsr166 |
1.1 |
* |
1202 |
dl |
1.62 |
* @return {@code true} if this task is known to have completed normally |
1203 |
jsr166 |
1.1 |
*/ |
1204 |
|
|
protected abstract boolean exec(); |
1205 |
|
|
|
1206 |
|
|
/** |
1207 |
jsr166 |
1.5 |
* Returns, but does not unschedule or execute, a task queued by |
1208 |
|
|
* the current thread but not yet executed, if one is immediately |
1209 |
dl |
1.66 |
* available. There is no guarantee that this task will actually |
1210 |
|
|
* be polled or executed next. Conversely, this method may return |
1211 |
|
|
* null even if a task exists but cannot be accessed without |
1212 |
|
|
* contention with other threads. This method is designed |
1213 |
jsr166 |
1.5 |
* primarily to support extensions, and is unlikely to be useful |
1214 |
jsr166 |
1.6 |
* otherwise. |
1215 |
|
|
* |
1216 |
jsr166 |
1.4 |
* @return the next task, or {@code null} if none are available |
1217 |
jsr166 |
1.1 |
*/ |
1218 |
|
|
protected static ForkJoinTask<?> peekNextLocalTask() { |
1219 |
dl |
1.66 |
Thread t; ForkJoinPool.WorkQueue q; |
1220 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
1221 |
|
|
q = ((ForkJoinWorkerThread)t).workQueue; |
1222 |
|
|
else |
1223 |
|
|
q = ForkJoinPool.commonSubmitterQueue(); |
1224 |
|
|
return (q == null) ? null : q.peek(); |
1225 |
jsr166 |
1.1 |
} |
1226 |
|
|
|
1227 |
|
|
/** |
1228 |
|
|
* Unschedules and returns, without executing, the next task |
1229 |
dl |
1.64 |
* queued by the current thread but not yet executed, if the |
1230 |
|
|
* current thread is operating in a ForkJoinPool. This method is |
1231 |
|
|
* designed primarily to support extensions, and is unlikely to be |
1232 |
|
|
* useful otherwise. |
1233 |
jsr166 |
1.1 |
* |
1234 |
jsr166 |
1.4 |
* @return the next task, or {@code null} if none are available |
1235 |
jsr166 |
1.1 |
*/ |
1236 |
|
|
protected static ForkJoinTask<?> pollNextLocalTask() { |
1237 |
dl |
1.64 |
Thread t; |
1238 |
|
|
return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1239 |
|
|
((ForkJoinWorkerThread)t).workQueue.nextLocalTask() : |
1240 |
|
|
null; |
1241 |
jsr166 |
1.1 |
} |
1242 |
|
|
|
1243 |
|
|
/** |
1244 |
dl |
1.64 |
* If the current thread is operating in a ForkJoinPool, |
1245 |
|
|
* unschedules and returns, without executing, the next task |
1246 |
jsr166 |
1.1 |
* queued by the current thread but not yet executed, if one is |
1247 |
|
|
* available, or if not available, a task that was forked by some |
1248 |
|
|
* other thread, if available. Availability may be transient, so a |
1249 |
dl |
1.64 |
* {@code null} result does not necessarily imply quiescence of |
1250 |
|
|
* the pool this task is operating in. This method is designed |
1251 |
jsr166 |
1.1 |
* primarily to support extensions, and is unlikely to be useful |
1252 |
jsr166 |
1.6 |
* otherwise. |
1253 |
|
|
* |
1254 |
jsr166 |
1.4 |
* @return a task, or {@code null} if none are available |
1255 |
jsr166 |
1.1 |
*/ |
1256 |
|
|
protected static ForkJoinTask<?> pollTask() { |
1257 |
dl |
1.64 |
Thread t; ForkJoinWorkerThread wt; |
1258 |
|
|
return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1259 |
|
|
(wt = (ForkJoinWorkerThread)t).pool.nextTaskFor(wt.workQueue) : |
1260 |
|
|
null; |
1261 |
dl |
1.54 |
} |
1262 |
|
|
|
1263 |
dl |
1.94 |
/** |
1264 |
|
|
* If the current thread is operating in a ForkJoinPool, |
1265 |
|
|
* unschedules and returns, without executing, a task externally |
1266 |
|
|
* submitted to the pool, if one is available. Availability may be |
1267 |
|
|
* transient, so a {@code null} result does not necessarily imply |
1268 |
|
|
* quiescence of the pool. This method is designed primarily to |
1269 |
|
|
* support extensions, and is unlikely to be useful otherwise. |
1270 |
|
|
* |
1271 |
|
|
* @return a task, or {@code null} if none are available |
1272 |
jsr166 |
1.107 |
* @since 9 |
1273 |
dl |
1.94 |
*/ |
1274 |
|
|
protected static ForkJoinTask<?> pollSubmission() { |
1275 |
dl |
1.96 |
Thread t; |
1276 |
dl |
1.94 |
return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1277 |
dl |
1.96 |
((ForkJoinWorkerThread)t).pool.pollSubmission() : null; |
1278 |
dl |
1.94 |
} |
1279 |
|
|
|
1280 |
dl |
1.60 |
// tag operations |
1281 |
dl |
1.54 |
|
1282 |
|
|
/** |
1283 |
dl |
1.60 |
* Returns the tag for this task. |
1284 |
dl |
1.54 |
* |
1285 |
dl |
1.60 |
* @return the tag for this task |
1286 |
dl |
1.54 |
* @since 1.8 |
1287 |
|
|
*/ |
1288 |
dl |
1.60 |
public final short getForkJoinTaskTag() { |
1289 |
|
|
return (short)status; |
1290 |
dl |
1.54 |
} |
1291 |
|
|
|
1292 |
|
|
/** |
1293 |
jsr166 |
1.102 |
* Atomically sets the tag value for this task and returns the old value. |
1294 |
dl |
1.54 |
* |
1295 |
jsr166 |
1.102 |
* @param newValue the new tag value |
1296 |
dl |
1.60 |
* @return the previous value of the tag |
1297 |
dl |
1.54 |
* @since 1.8 |
1298 |
|
|
*/ |
1299 |
jsr166 |
1.102 |
public final short setForkJoinTaskTag(short newValue) { |
1300 |
dl |
1.54 |
for (int s;;) { |
1301 |
dl |
1.109 |
if (STATUS.compareAndSet(this, s = status, |
1302 |
|
|
(s & ~SMASK) | (newValue & SMASK))) |
1303 |
dl |
1.60 |
return (short)s; |
1304 |
dl |
1.54 |
} |
1305 |
|
|
} |
1306 |
|
|
|
1307 |
|
|
/** |
1308 |
dl |
1.60 |
* Atomically conditionally sets the tag value for this task. |
1309 |
|
|
* Among other applications, tags can be used as visit markers |
1310 |
dl |
1.61 |
* in tasks operating on graphs, as in methods that check: {@code |
1311 |
dl |
1.60 |
* if (task.compareAndSetForkJoinTaskTag((short)0, (short)1))} |
1312 |
|
|
* before processing, otherwise exiting because the node has |
1313 |
|
|
* already been visited. |
1314 |
dl |
1.54 |
* |
1315 |
jsr166 |
1.102 |
* @param expect the expected tag value |
1316 |
|
|
* @param update the new tag value |
1317 |
jsr166 |
1.76 |
* @return {@code true} if successful; i.e., the current value was |
1318 |
jsr166 |
1.102 |
* equal to {@code expect} and was changed to {@code update}. |
1319 |
dl |
1.54 |
* @since 1.8 |
1320 |
|
|
*/ |
1321 |
jsr166 |
1.102 |
public final boolean compareAndSetForkJoinTaskTag(short expect, short update) { |
1322 |
dl |
1.54 |
for (int s;;) { |
1323 |
jsr166 |
1.102 |
if ((short)(s = status) != expect) |
1324 |
dl |
1.54 |
return false; |
1325 |
dl |
1.109 |
if (STATUS.compareAndSet(this, s, |
1326 |
|
|
(s & ~SMASK) | (update & SMASK))) |
1327 |
dl |
1.54 |
return true; |
1328 |
|
|
} |
1329 |
jsr166 |
1.1 |
} |
1330 |
|
|
|
1331 |
jsr166 |
1.5 |
/** |
1332 |
jsr166 |
1.95 |
* Adapter for Runnables. This implements RunnableFuture |
1333 |
jsr166 |
1.5 |
* to be compliant with AbstractExecutorService constraints |
1334 |
|
|
* when used in ForkJoinPool. |
1335 |
|
|
*/ |
1336 |
|
|
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
1337 |
|
|
implements RunnableFuture<T> { |
1338 |
|
|
final Runnable runnable; |
1339 |
|
|
T result; |
1340 |
|
|
AdaptedRunnable(Runnable runnable, T result) { |
1341 |
|
|
if (runnable == null) throw new NullPointerException(); |
1342 |
|
|
this.runnable = runnable; |
1343 |
dl |
1.59 |
this.result = result; // OK to set this even before completion |
1344 |
jsr166 |
1.5 |
} |
1345 |
dl |
1.59 |
public final T getRawResult() { return result; } |
1346 |
|
|
public final void setRawResult(T v) { result = v; } |
1347 |
|
|
public final boolean exec() { runnable.run(); return true; } |
1348 |
|
|
public final void run() { invoke(); } |
1349 |
|
|
private static final long serialVersionUID = 5232453952276885070L; |
1350 |
|
|
} |
1351 |
|
|
|
1352 |
|
|
/** |
1353 |
jsr166 |
1.99 |
* Adapter for Runnables without results. |
1354 |
dl |
1.59 |
*/ |
1355 |
|
|
static final class AdaptedRunnableAction extends ForkJoinTask<Void> |
1356 |
|
|
implements RunnableFuture<Void> { |
1357 |
|
|
final Runnable runnable; |
1358 |
|
|
AdaptedRunnableAction(Runnable runnable) { |
1359 |
|
|
if (runnable == null) throw new NullPointerException(); |
1360 |
|
|
this.runnable = runnable; |
1361 |
jsr166 |
1.5 |
} |
1362 |
dl |
1.59 |
public final Void getRawResult() { return null; } |
1363 |
|
|
public final void setRawResult(Void v) { } |
1364 |
|
|
public final boolean exec() { runnable.run(); return true; } |
1365 |
|
|
public final void run() { invoke(); } |
1366 |
jsr166 |
1.5 |
private static final long serialVersionUID = 5232453952276885070L; |
1367 |
|
|
} |
1368 |
|
|
|
1369 |
|
|
/** |
1370 |
jsr166 |
1.99 |
* Adapter for Runnables in which failure forces worker exception. |
1371 |
dl |
1.73 |
*/ |
1372 |
|
|
static final class RunnableExecuteAction extends ForkJoinTask<Void> { |
1373 |
|
|
final Runnable runnable; |
1374 |
|
|
RunnableExecuteAction(Runnable runnable) { |
1375 |
|
|
if (runnable == null) throw new NullPointerException(); |
1376 |
|
|
this.runnable = runnable; |
1377 |
|
|
} |
1378 |
|
|
public final Void getRawResult() { return null; } |
1379 |
|
|
public final void setRawResult(Void v) { } |
1380 |
|
|
public final boolean exec() { runnable.run(); return true; } |
1381 |
|
|
void internalPropagateException(Throwable ex) { |
1382 |
|
|
rethrow(ex); // rethrow outside exec() catches. |
1383 |
|
|
} |
1384 |
|
|
private static final long serialVersionUID = 5232453952276885070L; |
1385 |
|
|
} |
1386 |
|
|
|
1387 |
|
|
/** |
1388 |
jsr166 |
1.99 |
* Adapter for Callables. |
1389 |
jsr166 |
1.5 |
*/ |
1390 |
|
|
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
1391 |
|
|
implements RunnableFuture<T> { |
1392 |
jsr166 |
1.6 |
final Callable<? extends T> callable; |
1393 |
jsr166 |
1.5 |
T result; |
1394 |
jsr166 |
1.6 |
AdaptedCallable(Callable<? extends T> callable) { |
1395 |
jsr166 |
1.5 |
if (callable == null) throw new NullPointerException(); |
1396 |
|
|
this.callable = callable; |
1397 |
|
|
} |
1398 |
dl |
1.59 |
public final T getRawResult() { return result; } |
1399 |
|
|
public final void setRawResult(T v) { result = v; } |
1400 |
|
|
public final boolean exec() { |
1401 |
jsr166 |
1.5 |
try { |
1402 |
|
|
result = callable.call(); |
1403 |
|
|
return true; |
1404 |
|
|
} catch (RuntimeException rex) { |
1405 |
|
|
throw rex; |
1406 |
|
|
} catch (Exception ex) { |
1407 |
|
|
throw new RuntimeException(ex); |
1408 |
|
|
} |
1409 |
|
|
} |
1410 |
dl |
1.59 |
public final void run() { invoke(); } |
1411 |
jsr166 |
1.5 |
private static final long serialVersionUID = 2838392045355241008L; |
1412 |
|
|
} |
1413 |
jsr166 |
1.2 |
|
1414 |
|
|
/** |
1415 |
jsr166 |
1.6 |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1416 |
|
|
* method of the given {@code Runnable} as its action, and returns |
1417 |
|
|
* a null result upon {@link #join}. |
1418 |
jsr166 |
1.2 |
* |
1419 |
|
|
* @param runnable the runnable action |
1420 |
|
|
* @return the task |
1421 |
|
|
*/ |
1422 |
jsr166 |
1.6 |
public static ForkJoinTask<?> adapt(Runnable runnable) { |
1423 |
dl |
1.59 |
return new AdaptedRunnableAction(runnable); |
1424 |
jsr166 |
1.2 |
} |
1425 |
|
|
|
1426 |
|
|
/** |
1427 |
jsr166 |
1.6 |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1428 |
|
|
* method of the given {@code Runnable} as its action, and returns |
1429 |
|
|
* the given result upon {@link #join}. |
1430 |
jsr166 |
1.2 |
* |
1431 |
|
|
* @param runnable the runnable action |
1432 |
|
|
* @param result the result upon completion |
1433 |
jsr166 |
1.82 |
* @param <T> the type of the result |
1434 |
jsr166 |
1.2 |
* @return the task |
1435 |
|
|
*/ |
1436 |
|
|
public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) { |
1437 |
jsr166 |
1.5 |
return new AdaptedRunnable<T>(runnable, result); |
1438 |
jsr166 |
1.2 |
} |
1439 |
|
|
|
1440 |
|
|
/** |
1441 |
jsr166 |
1.6 |
* Returns a new {@code ForkJoinTask} that performs the {@code call} |
1442 |
|
|
* method of the given {@code Callable} as its action, and returns |
1443 |
|
|
* its result upon {@link #join}, translating any checked exceptions |
1444 |
|
|
* encountered into {@code RuntimeException}. |
1445 |
jsr166 |
1.2 |
* |
1446 |
|
|
* @param callable the callable action |
1447 |
jsr166 |
1.82 |
* @param <T> the type of the callable's result |
1448 |
jsr166 |
1.2 |
* @return the task |
1449 |
|
|
*/ |
1450 |
jsr166 |
1.6 |
public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) { |
1451 |
jsr166 |
1.5 |
return new AdaptedCallable<T>(callable); |
1452 |
jsr166 |
1.2 |
} |
1453 |
|
|
|
1454 |
jsr166 |
1.1 |
// Serialization support |
1455 |
|
|
|
1456 |
|
|
private static final long serialVersionUID = -7721805057305804111L; |
1457 |
|
|
|
1458 |
|
|
/** |
1459 |
jsr166 |
1.53 |
* Saves this task to a stream (that is, serializes it). |
1460 |
jsr166 |
1.1 |
* |
1461 |
jsr166 |
1.83 |
* @param s the stream |
1462 |
jsr166 |
1.84 |
* @throws java.io.IOException if an I/O error occurs |
1463 |
jsr166 |
1.1 |
* @serialData the current run status and the exception thrown |
1464 |
jsr166 |
1.4 |
* during execution, or {@code null} if none |
1465 |
jsr166 |
1.1 |
*/ |
1466 |
|
|
private void writeObject(java.io.ObjectOutputStream s) |
1467 |
|
|
throws java.io.IOException { |
1468 |
|
|
s.defaultWriteObject(); |
1469 |
|
|
s.writeObject(getException()); |
1470 |
|
|
} |
1471 |
|
|
|
1472 |
|
|
/** |
1473 |
jsr166 |
1.53 |
* Reconstitutes this task from a stream (that is, deserializes it). |
1474 |
jsr166 |
1.83 |
* @param s the stream |
1475 |
jsr166 |
1.84 |
* @throws ClassNotFoundException if the class of a serialized object |
1476 |
|
|
* could not be found |
1477 |
|
|
* @throws java.io.IOException if an I/O error occurs |
1478 |
jsr166 |
1.1 |
*/ |
1479 |
|
|
private void readObject(java.io.ObjectInputStream s) |
1480 |
|
|
throws java.io.IOException, ClassNotFoundException { |
1481 |
|
|
s.defaultReadObject(); |
1482 |
|
|
Object ex = s.readObject(); |
1483 |
|
|
if (ex != null) |
1484 |
dl |
1.45 |
setExceptionalCompletion((Throwable)ex); |
1485 |
jsr166 |
1.1 |
} |
1486 |
|
|
|
1487 |
dl |
1.109 |
// VarHandle mechanics |
1488 |
|
|
private static final VarHandle STATUS; |
1489 |
dl |
1.45 |
static { |
1490 |
jsr166 |
1.1 |
try { |
1491 |
dl |
1.109 |
MethodHandles.Lookup l = MethodHandles.lookup(); |
1492 |
|
|
STATUS = l.findVarHandle(ForkJoinTask.class, "status", int.class); |
1493 |
jsr166 |
1.91 |
} catch (ReflectiveOperationException e) { |
1494 |
dl |
1.45 |
throw new Error(e); |
1495 |
jsr166 |
1.1 |
} |
1496 |
|
|
} |
1497 |
dl |
1.45 |
|
1498 |
jsr166 |
1.1 |
} |