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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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package jsr166y; |
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import java.util.concurrent.*; |
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import java.io.Serializable; |
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import java.util.Collection; |
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import java.util.Collections; |
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import java.util.List; |
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import java.util.RandomAccess; |
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import java.util.Map; |
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import java.util.WeakHashMap; |
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import java.lang.ref.WeakReference; |
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import java.lang.ref.ReferenceQueue; |
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import java.util.concurrent.Callable; |
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import java.util.concurrent.CancellationException; |
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import java.util.concurrent.ExecutionException; |
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import java.util.concurrent.Future; |
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import java.util.concurrent.RejectedExecutionException; |
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import java.util.concurrent.RunnableFuture; |
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import java.util.concurrent.TimeUnit; |
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import java.util.concurrent.TimeoutException; |
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import java.util.concurrent.locks.ReentrantLock; |
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import java.lang.reflect.Constructor; |
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/** |
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* Abstract base class for tasks that run within a {@link ForkJoinPool}. |
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* start other subtasks. As indicated by the name of this class, |
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* many programs using {@code ForkJoinTask} employ only methods |
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* {@link #fork} and {@link #join}, or derivatives such as {@link |
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* #invokeAll}. However, this class also provides a number of other |
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* methods that can come into play in advanced usages, as well as |
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* extension mechanics that allow support of new forms of fork/join |
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* processing. |
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* #invokeAll(ForkJoinTask...) invokeAll}. However, this class also |
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* provides a number of other methods that can come into play in |
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* advanced usages, as well as extension mechanics that allow |
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* support of new forms of fork/join processing. |
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* |
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* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}. |
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* The efficiency of {@code ForkJoinTask}s stems from a set of |
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* 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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* internal task queues. Rethrown exceptions behave in the same way as |
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* regular exceptions, but, when possible, contain stack traces (as |
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* displayed for example using {@code ex.printStackTrace()}) of both |
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* the thread that initiated the computation as well as the thread |
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* actually encountering the exception; minimally only the latter. |
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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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* ForkJoinTasks (as may be determined using method {@link |
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* #inForkJoinPool}). Attempts to invoke them in other contexts |
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* result in exceptions or errors, possibly including |
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* ClassCastException. |
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* {@code ClassCastException}. |
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* |
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* <p>Method {@link #join} and its variants are appropriate for use |
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* only when completion dependencies are acyclic; that is, the |
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* parallel computation can be described as a directed acyclic graph |
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* (DAG). Otherwise, executions may encounter a form of deadlock as |
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* tasks cyclically wait for each other. However, this framework |
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* supports other methods and techniques (for example the use of |
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* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that |
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* may be of use in constructing custom subclasses for problems that |
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* are not statically structured as DAGs. |
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* |
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* <p>Most base support methods are {@code final}, to prevent |
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* overriding of implementations that are intrinsically tied to the |
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* computation. Large tasks should be split into smaller subtasks, |
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* usually via recursive decomposition. As a very rough rule of thumb, |
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* a task should perform more than 100 and less than 10000 basic |
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* computational steps. If tasks are too big, then parallelism cannot |
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* improve throughput. If too small, then memory and internal task |
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* maintenance overhead may overwhelm processing. |
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* computational steps, and should avoid indefinite looping. If tasks |
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* are too big, then parallelism cannot improve throughput. If too |
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* small, then memory and internal task maintenance overhead may |
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* overwhelm processing. |
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* |
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* <p>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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* See the internal documentation of class ForkJoinPool for a |
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* general implementation overview. ForkJoinTasks are mainly |
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* responsible for maintaining their "status" field amidst relays |
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* to methods in ForkJoinWorkerThread and ForkJoinPool. The |
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* methods of this class are more-or-less layered into (1) basic |
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* status maintenance (2) execution and awaiting completion (3) |
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* user-level methods that additionally report results. This is |
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* sometimes hard to see because this file orders exported methods |
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* in a way that flows well in javadocs. In particular, most |
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* join mechanics are in method quietlyJoin, below. |
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* to methods in ForkJoinWorkerThread and ForkJoinPool. |
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* |
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* The methods of this class are more-or-less layered into |
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* (1) basic status maintenance |
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* (2) execution and awaiting completion |
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* (3) user-level methods that additionally report results. |
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* This is sometimes hard to see because this file orders exported |
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* methods in a way that flows well in javadocs. |
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*/ |
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|
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/* |
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* single int to minimize footprint and to ensure atomicity (via |
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* CAS). Status is initially zero, and takes on nonnegative |
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* values until completed, upon which status holds value |
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* COMPLETED. CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking |
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* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking |
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* waits by other threads have the SIGNAL bit set. Completion of |
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* a stolen task with SIGNAL set awakens any waiters via |
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* notifyAll. Even though suboptimal for some purposes, we use |
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|
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/** The run status of this task */ |
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volatile int status; // accessed directly by pool and workers |
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|
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private static final int NORMAL = -1; |
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private static final int CANCELLED = -2; |
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private static final int EXCEPTIONAL = -3; |
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private static final int SIGNAL = 1; |
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|
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/** |
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* Table of exceptions thrown by tasks, to enable reporting by |
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* callers. Because exceptions are rare, we don't directly keep |
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* them with task objects, but instead use a weak ref table. Note |
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* that cancellation exceptions don't appear in the table, but are |
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* instead recorded as status values. |
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* TODO: Use ConcurrentReferenceHashMap |
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*/ |
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static final Map<ForkJoinTask<?>, Throwable> exceptionMap = |
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Collections.synchronizedMap |
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(new WeakHashMap<ForkJoinTask<?>, Throwable>()); |
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|
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// Maintaining completion status |
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|
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/** |
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* Marks completion and wakes up threads waiting to join this task, |
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* also clearing signal request bits. |
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* |
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* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL |
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* @return completion status on exit |
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*/ |
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private void setCompletion(int completion) { |
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int s; |
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while ((s = status) >= 0) { |
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private int setCompletion(int completion) { |
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for (int s;;) { |
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if ((s = status) < 0) |
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return s; |
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if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) { |
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if (s != 0) |
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synchronized (this) { notifyAll(); } |
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break; |
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return completion; |
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} |
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} |
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} |
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|
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/** |
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* Record exception and set exceptional completion |
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* @return status on exit |
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*/ |
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private void setExceptionalCompletion(Throwable rex) { |
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exceptionMap.put(this, rex); |
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setCompletion(EXCEPTIONAL); |
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} |
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|
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/** |
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* Blocks a worker thread until completion. Called only by pool. |
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* Tries to block a worker thread until completed or timed out. |
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* Uses Object.wait time argument conventions. |
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* May fail on contention or interrupt. |
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* |
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* @param millis if > 0, wait time. |
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*/ |
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final void internalAwaitDone() { |
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int s; // the odd construction reduces lock bias effects |
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while ((s = status) >= 0) { |
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try { |
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synchronized(this) { |
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if (UNSAFE.compareAndSwapInt(this, statusOffset, s,SIGNAL)) |
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wait(); |
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final void tryAwaitDone(long millis) { |
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int s; |
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try { |
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if (((s = status) > 0 || |
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(s == 0 && |
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UNSAFE.compareAndSwapInt(this, statusOffset, 0, SIGNAL))) && |
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status > 0) { |
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synchronized (this) { |
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if (status > 0) |
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wait(millis); |
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} |
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} catch (InterruptedException ie) { |
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cancelIfTerminating(); |
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} |
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} catch (InterruptedException ie) { |
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// caller must check termination |
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} |
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} |
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|
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/** |
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* Blocks a non-worker-thread until completion. |
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* @return status upon completion |
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*/ |
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private void externalAwaitDone() { |
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private int externalAwaitDone() { |
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int s; |
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while ((s = status) >= 0) { |
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synchronized(this) { |
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if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)){ |
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boolean interrupted = false; |
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while (status >= 0) { |
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if ((s = status) >= 0) { |
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boolean interrupted = false; |
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synchronized (this) { |
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while ((s = status) >= 0) { |
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if (s == 0) |
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UNSAFE.compareAndSwapInt(this, statusOffset, |
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0, SIGNAL); |
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else { |
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try { |
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wait(); |
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} catch (InterruptedException ie) { |
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interrupted = true; |
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} |
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} |
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if (interrupted) |
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Thread.currentThread().interrupt(); |
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break; |
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} |
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} |
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if (interrupted) |
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Thread.currentThread().interrupt(); |
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} |
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return s; |
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} |
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|
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/** |
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* Unless done, calls exec and records status if completed, but |
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* doesn't wait for completion otherwise. Primary execution method |
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* for ForkJoinWorkerThread. |
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* Blocks a non-worker-thread until completion or interruption or timeout. |
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*/ |
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final void quietlyExec() { |
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try { |
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if (status < 0 || !exec()) |
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> |
private int externalInterruptibleAwaitDone(long millis) |
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> |
throws InterruptedException { |
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> |
int s; |
275 |
> |
if (Thread.interrupted()) |
276 |
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throw new InterruptedException(); |
277 |
> |
if ((s = status) >= 0) { |
278 |
> |
synchronized (this) { |
279 |
> |
while ((s = status) >= 0) { |
280 |
> |
if (s == 0) |
281 |
> |
UNSAFE.compareAndSwapInt(this, statusOffset, |
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> |
0, SIGNAL); |
283 |
> |
else { |
284 |
> |
wait(millis); |
285 |
> |
if (millis > 0L) |
286 |
> |
break; |
287 |
> |
} |
288 |
> |
} |
289 |
> |
} |
290 |
> |
} |
291 |
> |
return s; |
292 |
> |
} |
293 |
> |
|
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> |
/** |
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* Primary execution method for stolen tasks. Unless done, calls |
296 |
> |
* exec and records status if completed, but doesn't wait for |
297 |
> |
* completion otherwise. |
298 |
> |
*/ |
299 |
> |
final void doExec() { |
300 |
> |
if (status >= 0) { |
301 |
> |
boolean completed; |
302 |
> |
try { |
303 |
> |
completed = exec(); |
304 |
> |
} catch (Throwable rex) { |
305 |
> |
setExceptionalCompletion(rex); |
306 |
|
return; |
307 |
+ |
} |
308 |
+ |
if (completed) |
309 |
+ |
setCompletion(NORMAL); // must be outside try block |
310 |
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} |
311 |
+ |
} |
312 |
+ |
|
313 |
+ |
/** |
314 |
+ |
* Primary mechanics for join, get, quietlyJoin. |
315 |
+ |
* @return status upon completion |
316 |
+ |
*/ |
317 |
+ |
private int doJoin() { |
318 |
+ |
Thread t; ForkJoinWorkerThread w; int s; boolean completed; |
319 |
+ |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) { |
320 |
+ |
if ((s = status) < 0) |
321 |
+ |
return s; |
322 |
+ |
if ((w = (ForkJoinWorkerThread)t).unpushTask(this)) { |
323 |
+ |
try { |
324 |
+ |
completed = exec(); |
325 |
+ |
} catch (Throwable rex) { |
326 |
+ |
return setExceptionalCompletion(rex); |
327 |
+ |
} |
328 |
+ |
if (completed) |
329 |
+ |
return setCompletion(NORMAL); |
330 |
+ |
} |
331 |
+ |
return w.joinTask(this); |
332 |
+ |
} |
333 |
+ |
else |
334 |
+ |
return externalAwaitDone(); |
335 |
+ |
} |
336 |
+ |
|
337 |
+ |
/** |
338 |
+ |
* Primary mechanics for invoke, quietlyInvoke. |
339 |
+ |
* @return status upon completion |
340 |
+ |
*/ |
341 |
+ |
private int doInvoke() { |
342 |
+ |
int s; boolean completed; |
343 |
+ |
if ((s = status) < 0) |
344 |
+ |
return s; |
345 |
+ |
try { |
346 |
+ |
completed = exec(); |
347 |
|
} catch (Throwable rex) { |
348 |
< |
setExceptionalCompletion(rex); |
349 |
< |
return; |
348 |
> |
return setExceptionalCompletion(rex); |
349 |
> |
} |
350 |
> |
if (completed) |
351 |
> |
return setCompletion(NORMAL); |
352 |
> |
else |
353 |
> |
return doJoin(); |
354 |
> |
} |
355 |
> |
|
356 |
> |
// Exception table support |
357 |
> |
|
358 |
> |
/** |
359 |
> |
* Table of exceptions thrown by tasks, to enable reporting by |
360 |
> |
* callers. Because exceptions are rare, we don't directly keep |
361 |
> |
* them with task objects, but instead use a weak ref table. Note |
362 |
> |
* that cancellation exceptions don't appear in the table, but are |
363 |
> |
* instead recorded as status values. |
364 |
> |
* |
365 |
> |
* Note: These statics are initialized below in static block. |
366 |
> |
*/ |
367 |
> |
private static final ExceptionNode[] exceptionTable; |
368 |
> |
private static final ReentrantLock exceptionTableLock; |
369 |
> |
private static final ReferenceQueue<Object> exceptionTableRefQueue; |
370 |
> |
|
371 |
> |
/** |
372 |
> |
* Fixed capacity for exceptionTable. |
373 |
> |
*/ |
374 |
> |
private static final int EXCEPTION_MAP_CAPACITY = 32; |
375 |
> |
|
376 |
> |
/** |
377 |
> |
* Key-value nodes for exception table. The chained hash table |
378 |
> |
* uses identity comparisons, full locking, and weak references |
379 |
> |
* for keys. The table has a fixed capacity because it only |
380 |
> |
* maintains task exceptions long enough for joiners to access |
381 |
> |
* them, so should never become very large for sustained |
382 |
> |
* periods. However, since we do not know when the last joiner |
383 |
> |
* completes, we must use weak references and expunge them. We do |
384 |
> |
* so on each operation (hence full locking). Also, some thread in |
385 |
> |
* any ForkJoinPool will call helpExpungeStaleExceptions when its |
386 |
> |
* pool becomes isQuiescent. |
387 |
> |
*/ |
388 |
> |
static final class ExceptionNode extends WeakReference<ForkJoinTask<?>>{ |
389 |
> |
final Throwable ex; |
390 |
> |
ExceptionNode next; |
391 |
> |
final long thrower; // use id not ref to avoid weak cycles |
392 |
> |
ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) { |
393 |
> |
super(task, exceptionTableRefQueue); |
394 |
> |
this.ex = ex; |
395 |
> |
this.next = next; |
396 |
> |
this.thrower = Thread.currentThread().getId(); |
397 |
> |
} |
398 |
> |
} |
399 |
> |
|
400 |
> |
/** |
401 |
> |
* Records exception and sets exceptional completion. |
402 |
> |
* |
403 |
> |
* @return status on exit |
404 |
> |
*/ |
405 |
> |
private int setExceptionalCompletion(Throwable ex) { |
406 |
> |
int h = System.identityHashCode(this); |
407 |
> |
final ReentrantLock lock = exceptionTableLock; |
408 |
> |
lock.lock(); |
409 |
> |
try { |
410 |
> |
expungeStaleExceptions(); |
411 |
> |
ExceptionNode[] t = exceptionTable; |
412 |
> |
int i = h & (t.length - 1); |
413 |
> |
for (ExceptionNode e = t[i]; ; e = e.next) { |
414 |
> |
if (e == null) { |
415 |
> |
t[i] = new ExceptionNode(this, ex, t[i]); |
416 |
> |
break; |
417 |
> |
} |
418 |
> |
if (e.get() == this) // already present |
419 |
> |
break; |
420 |
> |
} |
421 |
> |
} finally { |
422 |
> |
lock.unlock(); |
423 |
> |
} |
424 |
> |
return setCompletion(EXCEPTIONAL); |
425 |
> |
} |
426 |
> |
|
427 |
> |
/** |
428 |
> |
* Removes exception node and clears status |
429 |
> |
*/ |
430 |
> |
private void clearExceptionalCompletion() { |
431 |
> |
int h = System.identityHashCode(this); |
432 |
> |
final ReentrantLock lock = exceptionTableLock; |
433 |
> |
lock.lock(); |
434 |
> |
try { |
435 |
> |
ExceptionNode[] t = exceptionTable; |
436 |
> |
int i = h & (t.length - 1); |
437 |
> |
ExceptionNode e = t[i]; |
438 |
> |
ExceptionNode pred = null; |
439 |
> |
while (e != null) { |
440 |
> |
ExceptionNode next = e.next; |
441 |
> |
if (e.get() == this) { |
442 |
> |
if (pred == null) |
443 |
> |
t[i] = next; |
444 |
> |
else |
445 |
> |
pred.next = next; |
446 |
> |
break; |
447 |
> |
} |
448 |
> |
pred = e; |
449 |
> |
e = next; |
450 |
> |
} |
451 |
> |
expungeStaleExceptions(); |
452 |
> |
status = 0; |
453 |
> |
} finally { |
454 |
> |
lock.unlock(); |
455 |
> |
} |
456 |
> |
} |
457 |
> |
|
458 |
> |
/** |
459 |
> |
* Returns a rethrowable exception for the given task, if |
460 |
> |
* available. To provide accurate stack traces, if the exception |
461 |
> |
* was not thrown by the current thread, we try to create a new |
462 |
> |
* exception of the same type as the one thrown, but with the |
463 |
> |
* recorded exception as its cause. If there is no such |
464 |
> |
* constructor, we instead try to use a no-arg constructor, |
465 |
> |
* followed by initCause, to the same effect. If none of these |
466 |
> |
* apply, or any fail due to other exceptions, we return the |
467 |
> |
* recorded exception, which is still correct, although it may |
468 |
> |
* contain a misleading stack trace. |
469 |
> |
* |
470 |
> |
* @return the exception, or null if none |
471 |
> |
*/ |
472 |
> |
private Throwable getThrowableException() { |
473 |
> |
if (status != EXCEPTIONAL) |
474 |
> |
return null; |
475 |
> |
int h = System.identityHashCode(this); |
476 |
> |
ExceptionNode e; |
477 |
> |
final ReentrantLock lock = exceptionTableLock; |
478 |
> |
lock.lock(); |
479 |
> |
try { |
480 |
> |
expungeStaleExceptions(); |
481 |
> |
ExceptionNode[] t = exceptionTable; |
482 |
> |
e = t[h & (t.length - 1)]; |
483 |
> |
while (e != null && e.get() != this) |
484 |
> |
e = e.next; |
485 |
> |
} finally { |
486 |
> |
lock.unlock(); |
487 |
> |
} |
488 |
> |
Throwable ex; |
489 |
> |
if (e == null || (ex = e.ex) == null) |
490 |
> |
return null; |
491 |
> |
if (e.thrower != Thread.currentThread().getId()) { |
492 |
> |
Class<? extends Throwable> ec = ex.getClass(); |
493 |
> |
try { |
494 |
> |
Constructor<?> noArgCtor = null; |
495 |
> |
Constructor<?>[] cs = ec.getConstructors();// public ctors only |
496 |
> |
for (int i = 0; i < cs.length; ++i) { |
497 |
> |
Constructor<?> c = cs[i]; |
498 |
> |
Class<?>[] ps = c.getParameterTypes(); |
499 |
> |
if (ps.length == 0) |
500 |
> |
noArgCtor = c; |
501 |
> |
else if (ps.length == 1 && ps[0] == Throwable.class) |
502 |
> |
return (Throwable)(c.newInstance(ex)); |
503 |
> |
} |
504 |
> |
if (noArgCtor != null) { |
505 |
> |
Throwable wx = (Throwable)(noArgCtor.newInstance()); |
506 |
> |
wx.initCause(ex); |
507 |
> |
return wx; |
508 |
> |
} |
509 |
> |
} catch (Exception ignore) { |
510 |
> |
} |
511 |
|
} |
512 |
< |
setCompletion(NORMAL); // must be outside try block |
512 |
> |
return ex; |
513 |
> |
} |
514 |
> |
|
515 |
> |
/** |
516 |
> |
* Poll stale refs and remove them. Call only while holding lock. |
517 |
> |
*/ |
518 |
> |
private static void expungeStaleExceptions() { |
519 |
> |
for (Object x; (x = exceptionTableRefQueue.poll()) != null;) { |
520 |
> |
if (x instanceof ExceptionNode) { |
521 |
> |
ForkJoinTask<?> key = ((ExceptionNode)x).get(); |
522 |
> |
ExceptionNode[] t = exceptionTable; |
523 |
> |
int i = System.identityHashCode(key) & (t.length - 1); |
524 |
> |
ExceptionNode e = t[i]; |
525 |
> |
ExceptionNode pred = null; |
526 |
> |
while (e != null) { |
527 |
> |
ExceptionNode next = e.next; |
528 |
> |
if (e == x) { |
529 |
> |
if (pred == null) |
530 |
> |
t[i] = next; |
531 |
> |
else |
532 |
> |
pred.next = next; |
533 |
> |
break; |
534 |
> |
} |
535 |
> |
pred = e; |
536 |
> |
e = next; |
537 |
> |
} |
538 |
> |
} |
539 |
> |
} |
540 |
> |
} |
541 |
> |
|
542 |
> |
/** |
543 |
> |
* If lock is available, poll stale refs and remove them. |
544 |
> |
* Called from ForkJoinPool when pools become quiescent. |
545 |
> |
*/ |
546 |
> |
static final void helpExpungeStaleExceptions() { |
547 |
> |
final ReentrantLock lock = exceptionTableLock; |
548 |
> |
if (lock.tryLock()) { |
549 |
> |
try { |
550 |
> |
expungeStaleExceptions(); |
551 |
> |
} finally { |
552 |
> |
lock.unlock(); |
553 |
> |
} |
554 |
> |
} |
555 |
> |
} |
556 |
> |
|
557 |
> |
/** |
558 |
> |
* Report the result of invoke or join; called only upon |
559 |
> |
* non-normal return of internal versions. |
560 |
> |
*/ |
561 |
> |
private V reportResult() { |
562 |
> |
int s; Throwable ex; |
563 |
> |
if ((s = status) == CANCELLED) |
564 |
> |
throw new CancellationException(); |
565 |
> |
if (s == EXCEPTIONAL && (ex = getThrowableException()) != null) |
566 |
> |
UNSAFE.throwException(ex); |
567 |
> |
return getRawResult(); |
568 |
|
} |
569 |
|
|
570 |
|
// public methods |
580 |
|
* #isDone} returning {@code true}. |
581 |
|
* |
582 |
|
* <p>This method may be invoked only from within {@code |
583 |
< |
* ForkJoinTask} computations (as may be determined using method |
583 |
> |
* ForkJoinPool} computations (as may be determined using method |
584 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
585 |
|
* result in exceptions or errors, possibly including {@code |
586 |
|
* ClassCastException}. |
594 |
|
} |
595 |
|
|
596 |
|
/** |
597 |
< |
* Returns the result of the computation when it {@link #isDone is done}. |
598 |
< |
* This method differs from {@link #get()} in that |
597 |
> |
* Returns the result of the computation when it {@link #isDone is |
598 |
> |
* done}. This method differs from {@link #get()} in that |
599 |
|
* abnormal completion results in {@code RuntimeException} or |
600 |
< |
* {@code Error}, not {@code ExecutionException}. |
600 |
> |
* {@code Error}, not {@code ExecutionException}, and that |
601 |
> |
* interrupts of the calling thread do <em>not</em> cause the |
602 |
> |
* method to abruptly return by throwing {@code |
603 |
> |
* InterruptedException}. |
604 |
|
* |
605 |
|
* @return the computed result |
606 |
|
*/ |
607 |
|
public final V join() { |
608 |
< |
quietlyJoin(); |
609 |
< |
Throwable ex; |
610 |
< |
if (status < NORMAL && (ex = getException()) != null) |
611 |
< |
UNSAFE.throwException(ex); |
312 |
< |
return getRawResult(); |
608 |
> |
if (doJoin() != NORMAL) |
609 |
> |
return reportResult(); |
610 |
> |
else |
611 |
> |
return getRawResult(); |
612 |
|
} |
613 |
|
|
614 |
|
/** |
615 |
|
* Commences performing this task, awaits its completion if |
616 |
< |
* necessary, and return its result, or throws an (unchecked) |
617 |
< |
* exception if the underlying computation did so. |
616 |
> |
* necessary, and returns its result, or throws an (unchecked) |
617 |
> |
* {@code RuntimeException} or {@code Error} if the underlying |
618 |
> |
* computation did so. |
619 |
|
* |
620 |
|
* @return the computed result |
621 |
|
*/ |
622 |
|
public final V invoke() { |
623 |
< |
quietlyInvoke(); |
624 |
< |
Throwable ex; |
625 |
< |
if (status < NORMAL && (ex = getException()) != null) |
626 |
< |
UNSAFE.throwException(ex); |
327 |
< |
return getRawResult(); |
623 |
> |
if (doInvoke() != NORMAL) |
624 |
> |
return reportResult(); |
625 |
> |
else |
626 |
> |
return getRawResult(); |
627 |
|
} |
628 |
|
|
629 |
|
/** |
630 |
|
* Forks the given tasks, returning when {@code isDone} holds for |
631 |
|
* each task or an (unchecked) exception is encountered, in which |
632 |
< |
* case the exception is rethrown. If either task encounters an |
633 |
< |
* exception, the other one may be, but is not guaranteed to be, |
634 |
< |
* cancelled. If both tasks throw an exception, then this method |
635 |
< |
* throws one of them. The individual status of each task may be |
636 |
< |
* checked using {@link #getException()} and related methods. |
632 |
> |
* case the exception is rethrown. If more than one task |
633 |
> |
* encounters an exception, then this method throws any one of |
634 |
> |
* these exceptions. If any task encounters an exception, the |
635 |
> |
* other may be cancelled. However, the execution status of |
636 |
> |
* individual tasks is not guaranteed upon exceptional return. The |
637 |
> |
* status of each task may be obtained using {@link |
638 |
> |
* #getException()} and related methods to check if they have been |
639 |
> |
* cancelled, completed normally or exceptionally, or left |
640 |
> |
* unprocessed. |
641 |
|
* |
642 |
|
* <p>This method may be invoked only from within {@code |
643 |
< |
* ForkJoinTask} computations (as may be determined using method |
643 |
> |
* ForkJoinPool} computations (as may be determined using method |
644 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
645 |
|
* result in exceptions or errors, possibly including {@code |
646 |
|
* ClassCastException}. |
658 |
|
/** |
659 |
|
* Forks the given tasks, returning when {@code isDone} holds for |
660 |
|
* each task or an (unchecked) exception is encountered, in which |
661 |
< |
* case the exception is rethrown. If any task encounters an |
662 |
< |
* exception, others may be, but are not guaranteed to be, |
663 |
< |
* cancelled. If more than one task encounters an exception, then |
664 |
< |
* this method throws any one of these exceptions. The individual |
665 |
< |
* status of each task may be checked using {@link #getException()} |
666 |
< |
* and related methods. |
661 |
> |
* case the exception is rethrown. If more than one task |
662 |
> |
* encounters an exception, then this method throws any one of |
663 |
> |
* these exceptions. If any task encounters an exception, others |
664 |
> |
* may be cancelled. However, the execution status of individual |
665 |
> |
* tasks is not guaranteed upon exceptional return. The status of |
666 |
> |
* each task may be obtained using {@link #getException()} and |
667 |
> |
* related methods to check if they have been cancelled, completed |
668 |
> |
* normally or exceptionally, or left unprocessed. |
669 |
|
* |
670 |
|
* <p>This method may be invoked only from within {@code |
671 |
< |
* ForkJoinTask} computations (as may be determined using method |
671 |
> |
* ForkJoinPool} computations (as may be determined using method |
672 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
673 |
|
* result in exceptions or errors, possibly including {@code |
674 |
|
* ClassCastException}. |
687 |
|
} |
688 |
|
else if (i != 0) |
689 |
|
t.fork(); |
690 |
< |
else { |
691 |
< |
t.quietlyInvoke(); |
387 |
< |
if (ex == null && t.status < NORMAL) |
388 |
< |
ex = t.getException(); |
389 |
< |
} |
690 |
> |
else if (t.doInvoke() < NORMAL && ex == null) |
691 |
> |
ex = t.getException(); |
692 |
|
} |
693 |
|
for (int i = 1; i <= last; ++i) { |
694 |
|
ForkJoinTask<?> t = tasks[i]; |
695 |
|
if (t != null) { |
696 |
|
if (ex != null) |
697 |
|
t.cancel(false); |
698 |
< |
else { |
699 |
< |
t.quietlyJoin(); |
398 |
< |
if (ex == null && t.status < NORMAL) |
399 |
< |
ex = t.getException(); |
400 |
< |
} |
698 |
> |
else if (t.doJoin() < NORMAL) |
699 |
> |
ex = t.getException(); |
700 |
|
} |
701 |
|
} |
702 |
|
if (ex != null) |
706 |
|
/** |
707 |
|
* Forks all tasks in the specified collection, returning when |
708 |
|
* {@code isDone} holds for each task or an (unchecked) exception |
709 |
< |
* is encountered. If any task encounters an exception, others |
710 |
< |
* may be, but are not guaranteed to be, cancelled. If more than |
711 |
< |
* one task encounters an exception, then this method throws any |
712 |
< |
* one of these exceptions. The individual status of each task |
713 |
< |
* may be checked using {@link #getException()} and related |
714 |
< |
* methods. The behavior of this operation is undefined if the |
715 |
< |
* specified collection is modified while the operation is in |
716 |
< |
* progress. |
709 |
> |
* is encountered, in which case the exception is rethrown. If |
710 |
> |
* more than one task encounters an exception, then this method |
711 |
> |
* throws any one of these exceptions. If any task encounters an |
712 |
> |
* exception, others may be cancelled. However, the execution |
713 |
> |
* status of individual tasks is not guaranteed upon exceptional |
714 |
> |
* return. The status of each task may be obtained using {@link |
715 |
> |
* #getException()} and related methods to check if they have been |
716 |
> |
* cancelled, completed normally or exceptionally, or left |
717 |
> |
* unprocessed. |
718 |
|
* |
719 |
|
* <p>This method may be invoked only from within {@code |
720 |
< |
* ForkJoinTask} computations (as may be determined using method |
720 |
> |
* ForkJoinPool} computations (as may be determined using method |
721 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
722 |
|
* result in exceptions or errors, possibly including {@code |
723 |
|
* ClassCastException}. |
744 |
|
} |
745 |
|
else if (i != 0) |
746 |
|
t.fork(); |
747 |
< |
else { |
748 |
< |
t.quietlyInvoke(); |
449 |
< |
if (ex == null && t.status < NORMAL) |
450 |
< |
ex = t.getException(); |
451 |
< |
} |
747 |
> |
else if (t.doInvoke() < NORMAL && ex == null) |
748 |
> |
ex = t.getException(); |
749 |
|
} |
750 |
|
for (int i = 1; i <= last; ++i) { |
751 |
|
ForkJoinTask<?> t = ts.get(i); |
752 |
|
if (t != null) { |
753 |
|
if (ex != null) |
754 |
|
t.cancel(false); |
755 |
< |
else { |
756 |
< |
t.quietlyJoin(); |
460 |
< |
if (ex == null && t.status < NORMAL) |
461 |
< |
ex = t.getException(); |
462 |
< |
} |
755 |
> |
else if (t.doJoin() < NORMAL) |
756 |
> |
ex = t.getException(); |
757 |
|
} |
758 |
|
} |
759 |
|
if (ex != null) |
763 |
|
|
764 |
|
/** |
765 |
|
* Attempts to cancel execution of this task. This attempt will |
766 |
< |
* fail if the task has already completed, has already been |
767 |
< |
* cancelled, or could not be cancelled for some other reason. If |
768 |
< |
* successful, and this task has not started when cancel is |
769 |
< |
* called, execution of this task is suppressed, {@link |
770 |
< |
* #isCancelled} will report true, and {@link #join} will result |
771 |
< |
* in a {@code CancellationException} being thrown. |
766 |
> |
* fail if the task has already completed or could not be |
767 |
> |
* cancelled for some other reason. If successful, and this task |
768 |
> |
* has not started when {@code cancel} is called, execution of |
769 |
> |
* this task is suppressed. After this method returns |
770 |
> |
* successfully, unless there is an intervening call to {@link |
771 |
> |
* #reinitialize}, subsequent calls to {@link #isCancelled}, |
772 |
> |
* {@link #isDone}, and {@code cancel} will return {@code true} |
773 |
> |
* and calls to {@link #join} and related methods will result in |
774 |
> |
* {@code CancellationException}. |
775 |
|
* |
776 |
|
* <p>This method may be overridden in subclasses, but if so, must |
777 |
< |
* still ensure that these minimal properties hold. In particular, |
778 |
< |
* the {@code cancel} method itself must not throw exceptions. |
777 |
> |
* still ensure that these properties hold. In particular, the |
778 |
> |
* {@code cancel} method itself must not throw exceptions. |
779 |
|
* |
780 |
|
* <p>This method is designed to be invoked by <em>other</em> |
781 |
|
* tasks. To terminate the current task, you can just return or |
782 |
|
* throw an unchecked exception from its computation method, or |
783 |
|
* invoke {@link #completeExceptionally}. |
784 |
|
* |
785 |
< |
* @param mayInterruptIfRunning this value is ignored in the |
786 |
< |
* default implementation because tasks are not |
787 |
< |
* cancelled via interruption |
785 |
> |
* @param mayInterruptIfRunning this value has no effect in the |
786 |
> |
* default implementation because interrupts are not used to |
787 |
> |
* control cancellation. |
788 |
|
* |
789 |
|
* @return {@code true} if this task is now cancelled |
790 |
|
*/ |
791 |
|
public boolean cancel(boolean mayInterruptIfRunning) { |
792 |
< |
setCompletion(CANCELLED); |
496 |
< |
return status == CANCELLED; |
792 |
> |
return setCompletion(CANCELLED) == CANCELLED; |
793 |
|
} |
794 |
|
|
795 |
|
/** |
805 |
|
} |
806 |
|
} |
807 |
|
|
512 |
– |
/** |
513 |
– |
* Cancels ignoring exceptions if worker is terminating |
514 |
– |
*/ |
515 |
– |
final void cancelIfTerminating() { |
516 |
– |
Thread t = Thread.currentThread(); |
517 |
– |
if ((t instanceof ForkJoinWorkerThread) && |
518 |
– |
((ForkJoinWorkerThread) t).isTerminating()) { |
519 |
– |
try { |
520 |
– |
cancel(false); |
521 |
– |
} catch (Throwable ignore) { |
522 |
– |
} |
523 |
– |
} |
524 |
– |
} |
525 |
– |
|
808 |
|
public final boolean isDone() { |
809 |
|
return status < 0; |
810 |
|
} |
844 |
|
int s = status; |
845 |
|
return ((s >= NORMAL) ? null : |
846 |
|
(s == CANCELLED) ? new CancellationException() : |
847 |
< |
exceptionMap.get(this)); |
847 |
> |
getThrowableException()); |
848 |
|
} |
849 |
|
|
850 |
|
/** |
869 |
|
|
870 |
|
/** |
871 |
|
* Completes this task, and if not already aborted or cancelled, |
872 |
< |
* returning a {@code null} result upon {@code join} and related |
873 |
< |
* operations. This method may be used to provide results for |
874 |
< |
* asynchronous tasks, or to provide alternative handling for |
875 |
< |
* tasks that would not otherwise complete normally. Its use in |
876 |
< |
* other situations is discouraged. This method is |
877 |
< |
* overridable, but overridden versions must invoke {@code super} |
878 |
< |
* implementation to maintain guarantees. |
872 |
> |
* returning the given value as the result of subsequent |
873 |
> |
* invocations of {@code join} and related operations. This method |
874 |
> |
* may be used to provide results for asynchronous tasks, or to |
875 |
> |
* provide alternative handling for tasks that would not otherwise |
876 |
> |
* complete normally. Its use in other situations is |
877 |
> |
* discouraged. This method is overridable, but overridden |
878 |
> |
* versions must invoke {@code super} implementation to maintain |
879 |
> |
* guarantees. |
880 |
|
* |
881 |
|
* @param value the result value for this task |
882 |
|
*/ |
890 |
|
setCompletion(NORMAL); |
891 |
|
} |
892 |
|
|
893 |
+ |
/** |
894 |
+ |
* Waits if necessary for the computation to complete, and then |
895 |
+ |
* retrieves its result. |
896 |
+ |
* |
897 |
+ |
* @return the computed result |
898 |
+ |
* @throws CancellationException if the computation was cancelled |
899 |
+ |
* @throws ExecutionException if the computation threw an |
900 |
+ |
* exception |
901 |
+ |
* @throws InterruptedException if the current thread is not a |
902 |
+ |
* member of a ForkJoinPool and was interrupted while waiting |
903 |
+ |
*/ |
904 |
|
public final V get() throws InterruptedException, ExecutionException { |
905 |
< |
quietlyJoin(); |
906 |
< |
if (Thread.interrupted()) |
907 |
< |
throw new InterruptedException(); |
908 |
< |
int s = status; |
909 |
< |
if (s < NORMAL) { |
910 |
< |
Throwable ex; |
911 |
< |
if (s == CANCELLED) |
618 |
< |
throw new CancellationException(); |
619 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
620 |
< |
throw new ExecutionException(ex); |
621 |
< |
} |
905 |
> |
int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ? |
906 |
> |
doJoin() : externalInterruptibleAwaitDone(0L); |
907 |
> |
Throwable ex; |
908 |
> |
if (s == CANCELLED) |
909 |
> |
throw new CancellationException(); |
910 |
> |
if (s == EXCEPTIONAL && (ex = getThrowableException()) != null) |
911 |
> |
throw new ExecutionException(ex); |
912 |
|
return getRawResult(); |
913 |
|
} |
914 |
|
|
915 |
+ |
/** |
916 |
+ |
* Waits if necessary for at most the given time for the computation |
917 |
+ |
* to complete, and then retrieves its result, if available. |
918 |
+ |
* |
919 |
+ |
* @param timeout the maximum time to wait |
920 |
+ |
* @param unit the time unit of the timeout argument |
921 |
+ |
* @return the computed result |
922 |
+ |
* @throws CancellationException if the computation was cancelled |
923 |
+ |
* @throws ExecutionException if the computation threw an |
924 |
+ |
* exception |
925 |
+ |
* @throws InterruptedException if the current thread is not a |
926 |
+ |
* member of a ForkJoinPool and was interrupted while waiting |
927 |
+ |
* @throws TimeoutException if the wait timed out |
928 |
+ |
*/ |
929 |
|
public final V get(long timeout, TimeUnit unit) |
930 |
|
throws InterruptedException, ExecutionException, TimeoutException { |
931 |
|
Thread t = Thread.currentThread(); |
628 |
– |
ForkJoinPool pool; |
932 |
|
if (t instanceof ForkJoinWorkerThread) { |
933 |
|
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
934 |
< |
if (status >= 0 && w.unpushTask(this)) |
935 |
< |
quietlyExec(); |
936 |
< |
pool = w.pool; |
937 |
< |
} |
938 |
< |
else |
939 |
< |
pool = null; |
940 |
< |
/* |
941 |
< |
* Timed wait loop intermixes cases for FJ (pool != null) and |
639 |
< |
* non FJ threads. For FJ, decrement pool count but don't try |
640 |
< |
* for replacement; increment count on completion. For non-FJ, |
641 |
< |
* deal with interrupts. This is messy, but a little less so |
642 |
< |
* than is splitting the FJ and nonFJ cases. |
643 |
< |
*/ |
644 |
< |
boolean interrupted = false; |
645 |
< |
boolean dec = false; // true if pool count decremented |
646 |
< |
for (;;) { |
647 |
< |
if (Thread.interrupted() && pool == null) { |
648 |
< |
interrupted = true; |
649 |
< |
break; |
650 |
< |
} |
651 |
< |
int s = status; |
652 |
< |
if (s < 0) |
653 |
< |
break; |
654 |
< |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, SIGNAL)) { |
655 |
< |
long startTime = System.nanoTime(); |
656 |
< |
long nanos = unit.toNanos(timeout); |
657 |
< |
long nt; // wait time |
658 |
< |
while (status >= 0 && |
659 |
< |
(nt = nanos - (System.nanoTime() - startTime)) > 0) { |
660 |
< |
if (pool != null && !dec) |
661 |
< |
dec = pool.tryDecrementRunningCount(); |
662 |
< |
else { |
663 |
< |
long ms = nt / 1000000; |
664 |
< |
int ns = (int) (nt % 1000000); |
665 |
< |
try { |
666 |
< |
synchronized(this) { |
667 |
< |
if (status >= 0) |
668 |
< |
wait(ms, ns); |
669 |
< |
} |
670 |
< |
} catch (InterruptedException ie) { |
671 |
< |
if (pool != null) |
672 |
< |
cancelIfTerminating(); |
673 |
< |
else { |
674 |
< |
interrupted = true; |
675 |
< |
break; |
676 |
< |
} |
677 |
< |
} |
934 |
> |
long nanos = unit.toNanos(timeout); |
935 |
> |
if (status >= 0) { |
936 |
> |
boolean completed = false; |
937 |
> |
if (w.unpushTask(this)) { |
938 |
> |
try { |
939 |
> |
completed = exec(); |
940 |
> |
} catch (Throwable rex) { |
941 |
> |
setExceptionalCompletion(rex); |
942 |
|
} |
943 |
|
} |
944 |
< |
break; |
944 |
> |
if (completed) |
945 |
> |
setCompletion(NORMAL); |
946 |
> |
else if (status >= 0 && nanos > 0) |
947 |
> |
w.pool.timedAwaitJoin(this, nanos); |
948 |
|
} |
949 |
|
} |
950 |
< |
if (pool != null && dec) |
951 |
< |
pool.incrementRunningCount(); |
952 |
< |
if (interrupted) |
953 |
< |
throw new InterruptedException(); |
954 |
< |
int es = status; |
955 |
< |
if (es != NORMAL) { |
950 |
> |
else { |
951 |
> |
long millis = unit.toMillis(timeout); |
952 |
> |
if (millis > 0) |
953 |
> |
externalInterruptibleAwaitDone(millis); |
954 |
> |
} |
955 |
> |
int s = status; |
956 |
> |
if (s != NORMAL) { |
957 |
|
Throwable ex; |
958 |
< |
if (es == CANCELLED) |
958 |
> |
if (s == CANCELLED) |
959 |
|
throw new CancellationException(); |
960 |
< |
if (es == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
960 |
> |
if (s != EXCEPTIONAL) |
961 |
> |
throw new TimeoutException(); |
962 |
> |
if ((ex = getThrowableException()) != null) |
963 |
|
throw new ExecutionException(ex); |
694 |
– |
throw new TimeoutException(); |
964 |
|
} |
965 |
|
return getRawResult(); |
966 |
|
} |
972 |
|
* known to have aborted. |
973 |
|
*/ |
974 |
|
public final void quietlyJoin() { |
975 |
< |
Thread t; |
707 |
< |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) { |
708 |
< |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
709 |
< |
if (status >= 0) { |
710 |
< |
if (w.unpushTask(this)) { |
711 |
< |
boolean completed; |
712 |
< |
try { |
713 |
< |
completed = exec(); |
714 |
< |
} catch (Throwable rex) { |
715 |
< |
setExceptionalCompletion(rex); |
716 |
< |
return; |
717 |
< |
} |
718 |
< |
if (completed) { |
719 |
< |
setCompletion(NORMAL); |
720 |
< |
return; |
721 |
< |
} |
722 |
< |
} |
723 |
< |
w.joinTask(this); |
724 |
< |
} |
725 |
< |
} |
726 |
< |
else |
727 |
< |
externalAwaitDone(); |
975 |
> |
doJoin(); |
976 |
|
} |
977 |
|
|
978 |
|
/** |
979 |
|
* Commences performing this task and awaits its completion if |
980 |
|
* necessary, without returning its result or throwing its |
981 |
< |
* exception. This method may be useful when processing |
734 |
< |
* collections of tasks when some have been cancelled or otherwise |
735 |
< |
* known to have aborted. |
981 |
> |
* exception. |
982 |
|
*/ |
983 |
|
public final void quietlyInvoke() { |
984 |
< |
if (status >= 0) { |
739 |
< |
boolean completed; |
740 |
< |
try { |
741 |
< |
completed = exec(); |
742 |
< |
} catch (Throwable rex) { |
743 |
< |
setExceptionalCompletion(rex); |
744 |
< |
return; |
745 |
< |
} |
746 |
< |
if (completed) |
747 |
< |
setCompletion(NORMAL); |
748 |
< |
else |
749 |
< |
quietlyJoin(); |
750 |
< |
} |
984 |
> |
doInvoke(); |
985 |
|
} |
986 |
|
|
987 |
|
/** |
992 |
|
* processed. |
993 |
|
* |
994 |
|
* <p>This method may be invoked only from within {@code |
995 |
< |
* ForkJoinTask} computations (as may be determined using method |
995 |
> |
* ForkJoinPool} computations (as may be determined using method |
996 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
997 |
|
* result in exceptions or errors, possibly including {@code |
998 |
|
* ClassCastException}. |
1011 |
|
* under any other usage conditions are not guaranteed. |
1012 |
|
* This method may be useful when executing |
1013 |
|
* pre-constructed trees of subtasks in loops. |
1014 |
+ |
* |
1015 |
+ |
* <p>Upon completion of this method, {@code isDone()} reports |
1016 |
+ |
* {@code false}, and {@code getException()} reports {@code |
1017 |
+ |
* null}. However, the value returned by {@code getRawResult} is |
1018 |
+ |
* unaffected. To clear this value, you can invoke {@code |
1019 |
+ |
* setRawResult(null)}. |
1020 |
|
*/ |
1021 |
|
public void reinitialize() { |
1022 |
|
if (status == EXCEPTIONAL) |
1023 |
< |
exceptionMap.remove(this); |
1024 |
< |
status = 0; |
1023 |
> |
clearExceptionalCompletion(); |
1024 |
> |
else |
1025 |
> |
status = 0; |
1026 |
|
} |
1027 |
|
|
1028 |
|
/** |
1039 |
|
} |
1040 |
|
|
1041 |
|
/** |
1042 |
< |
* Returns {@code true} if the current thread is executing as a |
1043 |
< |
* ForkJoinPool computation. |
1042 |
> |
* Returns {@code true} if the current thread is a {@link |
1043 |
> |
* ForkJoinWorkerThread} executing as a ForkJoinPool computation. |
1044 |
|
* |
1045 |
< |
* @return {@code true} if the current thread is executing as a |
1046 |
< |
* ForkJoinPool computation, or false otherwise |
1045 |
> |
* @return {@code true} if the current thread is a {@link |
1046 |
> |
* ForkJoinWorkerThread} executing as a ForkJoinPool computation, |
1047 |
> |
* or {@code false} otherwise |
1048 |
|
*/ |
1049 |
|
public static boolean inForkJoinPool() { |
1050 |
|
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
1059 |
|
* were not, stolen. |
1060 |
|
* |
1061 |
|
* <p>This method may be invoked only from within {@code |
1062 |
< |
* ForkJoinTask} computations (as may be determined using method |
1062 |
> |
* ForkJoinPool} computations (as may be determined using method |
1063 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1064 |
|
* result in exceptions or errors, possibly including {@code |
1065 |
|
* ClassCastException}. |
1078 |
|
* fork other tasks. |
1079 |
|
* |
1080 |
|
* <p>This method may be invoked only from within {@code |
1081 |
< |
* ForkJoinTask} computations (as may be determined using method |
1081 |
> |
* ForkJoinPool} computations (as may be determined using method |
1082 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1083 |
|
* result in exceptions or errors, possibly including {@code |
1084 |
|
* ClassCastException}. |
1101 |
|
* exceeded. |
1102 |
|
* |
1103 |
|
* <p>This method may be invoked only from within {@code |
1104 |
< |
* ForkJoinTask} computations (as may be determined using method |
1104 |
> |
* ForkJoinPool} computations (as may be determined using method |
1105 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1106 |
|
* result in exceptions or errors, possibly including {@code |
1107 |
|
* ClassCastException}. |
1159 |
|
* otherwise. |
1160 |
|
* |
1161 |
|
* <p>This method may be invoked only from within {@code |
1162 |
< |
* ForkJoinTask} computations (as may be determined using method |
1162 |
> |
* ForkJoinPool} computations (as may be determined using method |
1163 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1164 |
|
* result in exceptions or errors, possibly including {@code |
1165 |
|
* ClassCastException}. |
1178 |
|
* be useful otherwise. |
1179 |
|
* |
1180 |
|
* <p>This method may be invoked only from within {@code |
1181 |
< |
* ForkJoinTask} computations (as may be determined using method |
1181 |
> |
* ForkJoinPool} computations (as may be determined using method |
1182 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1183 |
|
* result in exceptions or errors, possibly including {@code |
1184 |
|
* ClassCastException}. |
1201 |
|
* otherwise. |
1202 |
|
* |
1203 |
|
* <p>This method may be invoked only from within {@code |
1204 |
< |
* ForkJoinTask} computations (as may be determined using method |
1204 |
> |
* ForkJoinPool} computations (as may be determined using method |
1205 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1206 |
|
* result in exceptions or errors, possibly including {@code |
1207 |
|
* ClassCastException}. |
1311 |
|
private static final long serialVersionUID = -7721805057305804111L; |
1312 |
|
|
1313 |
|
/** |
1314 |
< |
* Saves the state to a stream. |
1314 |
> |
* Saves the state to a stream (that is, serializes it). |
1315 |
|
* |
1316 |
|
* @serialData the current run status and the exception thrown |
1317 |
|
* during execution, or {@code null} if none |
1324 |
|
} |
1325 |
|
|
1326 |
|
/** |
1327 |
< |
* Reconstitutes the instance from a stream. |
1327 |
> |
* Reconstitutes the instance from a stream (that is, deserializes it). |
1328 |
|
* |
1329 |
|
* @param s the stream |
1330 |
|
*/ |
1333 |
|
s.defaultReadObject(); |
1334 |
|
Object ex = s.readObject(); |
1335 |
|
if (ex != null) |
1336 |
< |
setExceptionalCompletion((Throwable) ex); |
1336 |
> |
setExceptionalCompletion((Throwable)ex); |
1337 |
|
} |
1338 |
|
|
1339 |
|
// Unsafe mechanics |
1340 |
< |
|
1341 |
< |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
1342 |
< |
private static final long statusOffset = |
1343 |
< |
objectFieldOffset("status", ForkJoinTask.class); |
1344 |
< |
|
1345 |
< |
private static long objectFieldOffset(String field, Class<?> klazz) { |
1340 |
> |
private static final sun.misc.Unsafe UNSAFE; |
1341 |
> |
private static final long statusOffset; |
1342 |
> |
static { |
1343 |
> |
exceptionTableLock = new ReentrantLock(); |
1344 |
> |
exceptionTableRefQueue = new ReferenceQueue<Object>(); |
1345 |
> |
exceptionTable = new ExceptionNode[EXCEPTION_MAP_CAPACITY]; |
1346 |
|
try { |
1347 |
< |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
1348 |
< |
} catch (NoSuchFieldException e) { |
1349 |
< |
// Convert Exception to corresponding Error |
1350 |
< |
NoSuchFieldError error = new NoSuchFieldError(field); |
1351 |
< |
error.initCause(e); |
1110 |
< |
throw error; |
1347 |
> |
UNSAFE = getUnsafe(); |
1348 |
> |
statusOffset = UNSAFE.objectFieldOffset |
1349 |
> |
(ForkJoinTask.class.getDeclaredField("status")); |
1350 |
> |
} catch (Exception e) { |
1351 |
> |
throw new Error(e); |
1352 |
|
} |
1353 |
|
} |
1354 |
|
|