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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.Executor; |
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import java.util.concurrent.ExecutorService; |
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import java.util.concurrent.Future; |
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import java.util.concurrent.RejectedExecutionException; |
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import java.util.concurrent.RunnableFuture; |
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import java.util.concurrent.TimeUnit; |
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import java.util.concurrent.TimeoutException; |
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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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* exceptions such as {@code IOExceptions} to be thrown. However, |
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* computations may still encounter unchecked exceptions, that are |
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* rethrown to callers attempting to join them. These exceptions may |
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* additionally include RejectedExecutionExceptions stemming from |
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* internal resource exhaustion such as failure to allocate internal |
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* task queues. |
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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. 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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* The {@link Future#get} methods support interruptible and/or timed |
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* waits for completion and report results using {@code Future} |
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* conventions. Method {@link #helpJoin} enables callers to actively |
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* execute other tasks while awaiting joins, which is sometimes more |
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* efficient but only applies when all subtasks are known to be |
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* strictly tree-structured. Method {@link #invoke} is semantically |
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* conventions. Method {@link #invoke} is semantically |
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* equivalent to {@code fork(); join()} but always attempts to begin |
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* execution in the current thread. The "<em>quiet</em>" forms of |
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* these methods do not extract results or report exceptions. These |
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* <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 #isCancelled} is true if completion was due to cancellation; |
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* {@link #isCompletedNormally} is true if a task completed without |
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* cancellation or encountering an exception; {@link |
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* #isCompletedExceptionally} is true if if the task encountered an |
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* exception (in which case {@link #getException} returns the |
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* exception); {@link #isCancelled} is true if the task was cancelled |
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* (in which case {@link #getException} returns a {@link |
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* java.util.concurrent.CancellationException}); and {@link |
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* #isCompletedAbnormally} is true if a task was either cancelled or |
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* encountered an exception. |
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* cancellation or encountering an exception; {@link #isCancelled} is |
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* true if the task was cancelled (in which case {@link #getException} |
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* returns a {@link java.util.concurrent.CancellationException}); and |
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* {@link #isCompletedAbnormally} is true if a task was either |
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* cancelled or encountered an exception, in which case {@link |
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* #getException} will return either the encountered exception or |
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* {@link java.util.concurrent.CancellationException}. |
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* |
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* <p>The ForkJoinTask class is not usually directly subclassed. |
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* Instead, you subclass one of the abstract classes that support a |
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* 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 |
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* java.lang.Runnable} and {@link java.util.concurrent.Callable}, that |
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* may be of use when mixing execution of ForkJoinTasks with other |
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* kinds of tasks. When all tasks are of this form, consider using a |
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* pool in {@link ForkJoinPool#setAsyncMode async mode}. |
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* <p>This class provides {@code adapt} methods for {@link Runnable} |
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* and {@link Callable}, that may be of use when mixing execution of |
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* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are |
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* of this form, consider using a pool constructed in <em>asyncMode</em>. |
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* |
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* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
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* used in extensions such as remote execution frameworks. It is |
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*/ |
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public abstract class ForkJoinTask<V> implements Future<V>, Serializable { |
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|
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/** |
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* Run control status bits packed into a single int to minimize |
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* footprint and to ensure atomicity (via CAS). Status is |
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* initially zero, and takes on nonnegative values until |
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* completed, upon which status holds COMPLETED. CANCELLED, or |
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* EXCEPTIONAL, which use the top 3 bits. Tasks undergoing |
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* blocking waits by other threads have SIGNAL_MASK bits set -- |
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* bit 15 for external (nonFJ) waits, and the rest a count of |
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* waiting FJ threads. (This representation relies on |
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* ForkJoinPool max thread limits). Completion of a stolen task |
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* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even |
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* though suboptimal for some purposes, we use basic builtin |
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* wait/notify to take advantage of "monitor inflation" in JVMs |
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* that we would otherwise need to emulate to avoid adding further |
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* per-task bookkeeping overhead. Note that bits 16-28 are |
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* currently unused. Also value 0x80000000 is available as spare |
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* completion value. |
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*/ |
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volatile int status; // accessed directly by pool and workers |
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|
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static final int COMPLETION_MASK = 0xe0000000; |
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static final int NORMAL = 0xe0000000; // == mask |
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static final int CANCELLED = 0xc0000000; |
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static final int EXCEPTIONAL = 0xa0000000; |
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static final int SIGNAL_MASK = 0x0000ffff; |
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static final int INTERNAL_SIGNAL_MASK = 0x00007fff; |
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static final int EXTERNAL_SIGNAL = 0x00008000; // top bit of low word |
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|
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/** |
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* Table of exceptions thrown by tasks, to enable reporting by |
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* callers. Because exceptions are rare, we don't directly keep |
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* them with task objects, but instead use a weak ref table. Note |
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* that cancellation exceptions don't appear in the table, but are |
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* instead recorded as status values. |
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* TODO: Use ConcurrentReferenceHashMap |
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*/ |
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static final Map<ForkJoinTask<?>, Throwable> exceptionMap = |
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Collections.synchronizedMap |
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(new WeakHashMap<ForkJoinTask<?>, Throwable>()); |
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|
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// within-package utilities |
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/** |
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* Gets current worker thread, or null if not a worker thread. |
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*/ |
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static ForkJoinWorkerThread getWorker() { |
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Thread t = Thread.currentThread(); |
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return ((t instanceof ForkJoinWorkerThread) ? |
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(ForkJoinWorkerThread) t : null); |
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} |
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|
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final boolean casStatus(int cmp, int val) { |
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return UNSAFE.compareAndSwapInt(this, statusOffset, cmp, val); |
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} |
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|
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/** |
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* Workaround for not being able to rethrow unchecked exceptions. |
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/* |
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* 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. |
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*/ |
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|
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/* |
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* The status field holds run control status bits packed into a |
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* single int to minimize footprint and to ensure atomicity (via |
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* CAS). Status is initially zero, and takes on nonnegative |
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* values until completed, upon which status holds value |
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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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* basic builtin wait/notify to take advantage of "monitor |
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* inflation" in JVMs that we would otherwise need to emulate to |
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* avoid adding further per-task bookkeeping overhead. We want |
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* these monitors to be "fat", i.e., not use biasing or thin-lock |
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* techniques, so use some odd coding idioms that tend to avoid |
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* them. |
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*/ |
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static void rethrowException(Throwable ex) { |
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if (ex != null) |
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UNSAFE.throwException(ex); |
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} |
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|
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// Setting completion status |
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/** The run status of this task */ |
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volatile int status; // accessed directly by pool and workers |
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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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* Marks completion and wakes up threads waiting to join this task. |
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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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final void setCompletion(int completion) { |
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ForkJoinPool pool = getPool(); |
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if (pool != null) { |
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int s; // Clear signal bits while setting completion status |
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do {} while ((s = status) >= 0 && !casStatus(s, completion)); |
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|
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if ((s & SIGNAL_MASK) != 0) { |
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if ((s &= INTERNAL_SIGNAL_MASK) != 0) |
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pool.updateRunningCount(s); |
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synchronized (this) { notifyAll(); } |
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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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return completion; |
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} |
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} |
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else |
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externallySetCompletion(completion); |
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} |
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|
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/** |
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* Version of setCompletion for non-FJ threads. Leaves signal |
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* bits for unblocked threads to adjust, and always notifies. |
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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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private void externallySetCompletion(int completion) { |
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final void tryAwaitDone(long millis) { |
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int s; |
236 |
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do {} while ((s = status) >= 0 && |
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!casStatus(s, (s & SIGNAL_MASK) | completion)); |
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synchronized (this) { notifyAll(); } |
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} |
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|
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/** |
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* Sets status to indicate normal completion. |
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*/ |
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final void setNormalCompletion() { |
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// Try typical fast case -- single CAS, no signal, not already done. |
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// Manually expand casStatus to improve chances of inlining it |
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if (!UNSAFE.compareAndSwapInt(this, statusOffset, 0, NORMAL)) |
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setCompletion(NORMAL); |
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} |
250 |
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|
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// internal waiting and notification |
252 |
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|
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/** |
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* Performs the actual monitor wait for awaitDone. |
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*/ |
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private void doAwaitDone() { |
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// Minimize lock bias and in/de-flation effects by maximizing |
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// chances of waiting inside sync |
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try { |
229 |
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while (status >= 0) |
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synchronized (this) { if (status >= 0) wait(); } |
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} catch (InterruptedException ie) { |
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onInterruptedWait(); |
233 |
< |
} |
234 |
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} |
235 |
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|
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/** |
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* Performs the actual timed monitor wait for awaitDone. |
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*/ |
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< |
private void doAwaitDone(long startTime, long nanos) { |
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synchronized (this) { |
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try { |
273 |
< |
while (status >= 0) { |
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< |
long nt = nanos - (System.nanoTime() - startTime); |
275 |
< |
if (nt <= 0) |
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< |
break; |
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< |
wait(nt / 1000000, (int) (nt % 1000000)); |
229 |
> |
if (((s = status) > 0 || |
230 |
> |
(s == 0 && |
231 |
> |
UNSAFE.compareAndSwapInt(this, statusOffset, 0, SIGNAL))) && |
232 |
> |
status > 0) { |
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synchronized (this) { |
234 |
> |
if (status > 0) |
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> |
wait(millis); |
236 |
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} |
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– |
} catch (InterruptedException ie) { |
280 |
– |
onInterruptedWait(); |
237 |
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} |
238 |
+ |
} catch (InterruptedException ie) { |
239 |
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// caller must check termination |
240 |
|
} |
241 |
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} |
242 |
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|
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– |
// Awaiting completion |
286 |
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|
243 |
|
/** |
244 |
< |
* Sets status to indicate there is joiner, then waits for join, |
245 |
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* surrounded with pool notifications. |
290 |
< |
* |
291 |
< |
* @return status upon exit |
244 |
> |
* Blocks a non-worker-thread until completion. |
245 |
> |
* @return status upon completion |
246 |
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*/ |
247 |
< |
private int awaitDone(ForkJoinWorkerThread w, |
294 |
< |
boolean maintainParallelism) { |
295 |
< |
ForkJoinPool pool = (w == null) ? null : w.pool; |
247 |
> |
private int externalAwaitDone() { |
248 |
|
int s; |
249 |
< |
while ((s = status) >= 0) { |
250 |
< |
if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) { |
251 |
< |
if (pool == null || !pool.preJoin(this, maintainParallelism)) |
252 |
< |
doAwaitDone(); |
253 |
< |
if (((s = status) & INTERNAL_SIGNAL_MASK) != 0) |
254 |
< |
adjustPoolCountsOnUnblock(pool); |
255 |
< |
break; |
249 |
> |
if ((s = status) >= 0) { |
250 |
> |
boolean interrupted = false; |
251 |
> |
synchronized (this) { |
252 |
> |
while ((s = status) >= 0) { |
253 |
> |
if (s == 0) |
254 |
> |
UNSAFE.compareAndSwapInt(this, statusOffset, |
255 |
> |
0, SIGNAL); |
256 |
> |
else { |
257 |
> |
try { |
258 |
> |
wait(); |
259 |
> |
} catch (InterruptedException ie) { |
260 |
> |
interrupted = true; |
261 |
> |
} |
262 |
> |
} |
263 |
> |
} |
264 |
|
} |
265 |
+ |
if (interrupted) |
266 |
+ |
Thread.currentThread().interrupt(); |
267 |
|
} |
268 |
|
return s; |
269 |
|
} |
270 |
|
|
271 |
|
/** |
272 |
< |
* Timed version of awaitDone |
311 |
< |
* |
312 |
< |
* @return status upon exit |
272 |
> |
* Blocks a non-worker-thread until completion or interruption or timeout. |
273 |
|
*/ |
274 |
< |
private int awaitDone(ForkJoinWorkerThread w, long nanos) { |
275 |
< |
ForkJoinPool pool = (w == null) ? null : w.pool; |
274 |
> |
private int externalInterruptibleAwaitDone(long millis) |
275 |
> |
throws InterruptedException { |
276 |
|
int s; |
277 |
< |
while ((s = status) >= 0) { |
278 |
< |
if (casStatus(s, (pool == null) ? s|EXTERNAL_SIGNAL : s+1)) { |
279 |
< |
long startTime = System.nanoTime(); |
280 |
< |
if (pool == null || !pool.preJoin(this, false)) |
281 |
< |
doAwaitDone(startTime, nanos); |
282 |
< |
if ((s = status) >= 0) { |
283 |
< |
adjustPoolCountsOnCancelledWait(pool); |
284 |
< |
s = status; |
277 |
> |
if (Thread.interrupted()) |
278 |
> |
throw new InterruptedException(); |
279 |
> |
if ((s = status) >= 0) { |
280 |
> |
synchronized (this) { |
281 |
> |
while ((s = status) >= 0) { |
282 |
> |
if (s == 0) |
283 |
> |
UNSAFE.compareAndSwapInt(this, statusOffset, |
284 |
> |
0, SIGNAL); |
285 |
> |
else { |
286 |
> |
wait(millis); |
287 |
> |
if (millis > 0L) |
288 |
> |
break; |
289 |
> |
} |
290 |
|
} |
326 |
– |
if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0) |
327 |
– |
adjustPoolCountsOnUnblock(pool); |
328 |
– |
break; |
291 |
|
} |
292 |
|
} |
293 |
|
return s; |
294 |
|
} |
295 |
|
|
296 |
|
/** |
297 |
< |
* Notifies pool that thread is unblocked. Called by signalled |
298 |
< |
* threads when woken by non-FJ threads (which is atypical). |
297 |
> |
* Primary execution method for stolen tasks. Unless done, calls |
298 |
> |
* exec and records status if completed, but doesn't wait for |
299 |
> |
* completion otherwise. |
300 |
|
*/ |
301 |
< |
private void adjustPoolCountsOnUnblock(ForkJoinPool pool) { |
302 |
< |
int s; |
303 |
< |
do {} while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK)); |
304 |
< |
if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0) |
305 |
< |
pool.updateRunningCount(s); |
301 |
> |
final void doExec() { |
302 |
> |
if (status >= 0) { |
303 |
> |
boolean completed; |
304 |
> |
try { |
305 |
> |
completed = exec(); |
306 |
> |
} catch (Throwable rex) { |
307 |
> |
setExceptionalCompletion(rex); |
308 |
> |
return; |
309 |
> |
} |
310 |
> |
if (completed) |
311 |
> |
setCompletion(NORMAL); // must be outside try block |
312 |
> |
} |
313 |
|
} |
314 |
|
|
315 |
|
/** |
316 |
< |
* Notifies pool to adjust counts on cancelled or timed out wait. |
316 |
> |
* Primary mechanics for join, get, quietlyJoin. |
317 |
> |
* @return status upon completion |
318 |
|
*/ |
319 |
< |
private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) { |
320 |
< |
if (pool != null) { |
321 |
< |
int s; |
322 |
< |
while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) { |
323 |
< |
if (casStatus(s, s - 1)) { |
324 |
< |
pool.updateRunningCount(1); |
325 |
< |
break; |
319 |
> |
private int doJoin() { |
320 |
> |
Thread t; ForkJoinWorkerThread w; int s; boolean completed; |
321 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) { |
322 |
> |
if ((s = status) < 0) |
323 |
> |
return s; |
324 |
> |
if ((w = (ForkJoinWorkerThread)t).unpushTask(this)) { |
325 |
> |
try { |
326 |
> |
completed = exec(); |
327 |
> |
} catch (Throwable rex) { |
328 |
> |
return setExceptionalCompletion(rex); |
329 |
|
} |
330 |
+ |
if (completed) |
331 |
+ |
return setCompletion(NORMAL); |
332 |
|
} |
333 |
+ |
return w.joinTask(this); |
334 |
|
} |
335 |
+ |
else |
336 |
+ |
return externalAwaitDone(); |
337 |
|
} |
338 |
|
|
339 |
|
/** |
340 |
< |
* Handles interruptions during waits. |
340 |
> |
* Primary mechanics for invoke, quietlyInvoke. |
341 |
> |
* @return status upon completion |
342 |
|
*/ |
343 |
< |
private void onInterruptedWait() { |
344 |
< |
ForkJoinWorkerThread w = getWorker(); |
345 |
< |
if (w == null) |
346 |
< |
Thread.currentThread().interrupt(); // re-interrupt |
347 |
< |
else if (w.isTerminating()) |
348 |
< |
cancelIgnoringExceptions(); |
349 |
< |
// else if FJworker, ignore interrupt |
343 |
> |
private int doInvoke() { |
344 |
> |
int s; boolean completed; |
345 |
> |
if ((s = status) < 0) |
346 |
> |
return s; |
347 |
> |
try { |
348 |
> |
completed = exec(); |
349 |
> |
} catch (Throwable rex) { |
350 |
> |
return setExceptionalCompletion(rex); |
351 |
> |
} |
352 |
> |
if (completed) |
353 |
> |
return setCompletion(NORMAL); |
354 |
> |
else |
355 |
> |
return doJoin(); |
356 |
|
} |
357 |
|
|
358 |
< |
// Recording and reporting exceptions |
373 |
< |
|
374 |
< |
private void setDoneExceptionally(Throwable rex) { |
375 |
< |
exceptionMap.put(this, rex); |
376 |
< |
setCompletion(EXCEPTIONAL); |
377 |
< |
} |
358 |
> |
// Exception table support |
359 |
|
|
360 |
|
/** |
361 |
< |
* Throws the exception associated with status s. |
361 |
> |
* Table of exceptions thrown by tasks, to enable reporting by |
362 |
> |
* callers. Because exceptions are rare, we don't directly keep |
363 |
> |
* them with task objects, but instead use a weak ref table. Note |
364 |
> |
* that cancellation exceptions don't appear in the table, but are |
365 |
> |
* instead recorded as status values. |
366 |
|
* |
367 |
< |
* @throws the exception |
367 |
> |
* Note: These statics are initialized below in static block. |
368 |
|
*/ |
369 |
< |
private void reportException(int s) { |
370 |
< |
if ((s &= COMPLETION_MASK) < NORMAL) { |
371 |
< |
if (s == CANCELLED) |
387 |
< |
throw new CancellationException(); |
388 |
< |
else |
389 |
< |
rethrowException(exceptionMap.get(this)); |
390 |
< |
} |
391 |
< |
} |
369 |
> |
private static final ExceptionNode[] exceptionTable; |
370 |
> |
private static final ReentrantLock exceptionTableLock; |
371 |
> |
private static final ReferenceQueue<Object> exceptionTableRefQueue; |
372 |
|
|
373 |
|
/** |
374 |
< |
* Returns result or throws exception using j.u.c.Future conventions. |
395 |
< |
* Only call when {@code isDone} known to be true. |
374 |
> |
* Fixed capacity for exceptionTable. |
375 |
|
*/ |
376 |
< |
private V reportFutureResult() |
398 |
< |
throws ExecutionException, InterruptedException { |
399 |
< |
if (Thread.interrupted()) |
400 |
< |
throw new InterruptedException(); |
401 |
< |
int s = status & COMPLETION_MASK; |
402 |
< |
if (s < NORMAL) { |
403 |
< |
Throwable ex; |
404 |
< |
if (s == CANCELLED) |
405 |
< |
throw new CancellationException(); |
406 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
407 |
< |
throw new ExecutionException(ex); |
408 |
< |
} |
409 |
< |
return getRawResult(); |
410 |
< |
} |
376 |
> |
private static final int EXCEPTION_MAP_CAPACITY = 32; |
377 |
|
|
378 |
|
/** |
379 |
< |
* Returns result or throws exception using j.u.c.Future conventions |
380 |
< |
* with timeouts. |
379 |
> |
* Key-value nodes for exception table. The chained hash table |
380 |
> |
* uses identity comparisons, full locking, and weak references |
381 |
> |
* for keys. The table has a fixed capacity because it only |
382 |
> |
* maintains task exceptions long enough for joiners to access |
383 |
> |
* them, so should never become very large for sustained |
384 |
> |
* periods. However, since we do not know when the last joiner |
385 |
> |
* completes, we must use weak references and expunge them. We do |
386 |
> |
* so on each operation (hence full locking). Also, some thread in |
387 |
> |
* any ForkJoinPool will call helpExpunge when its pool becomes |
388 |
> |
* isQuiescent. |
389 |
|
*/ |
390 |
< |
private V reportTimedFutureResult() |
391 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
392 |
< |
if (Thread.interrupted()) |
393 |
< |
throw new InterruptedException(); |
394 |
< |
Throwable ex; |
395 |
< |
int s = status & COMPLETION_MASK; |
396 |
< |
if (s == NORMAL) |
397 |
< |
return getRawResult(); |
398 |
< |
if (s == CANCELLED) |
399 |
< |
throw new CancellationException(); |
426 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
427 |
< |
throw new ExecutionException(ex); |
428 |
< |
throw new TimeoutException(); |
390 |
> |
static final class ExceptionNode extends WeakReference<ForkJoinTask<?>>{ |
391 |
> |
final Throwable ex; |
392 |
> |
ExceptionNode next; |
393 |
> |
final long thrower; |
394 |
> |
ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) { |
395 |
> |
super(task, exceptionTableRefQueue); |
396 |
> |
this.ex = ex; |
397 |
> |
this.next = next; |
398 |
> |
this.thrower = Thread.currentThread().getId(); |
399 |
> |
} |
400 |
|
} |
401 |
|
|
431 |
– |
// internal execution methods |
432 |
– |
|
402 |
|
/** |
403 |
< |
* Calls exec, recording completion, and rethrowing exception if |
435 |
< |
* encountered. Caller should normally check status before calling. |
403 |
> |
* Records exception and sets exceptional completion. |
404 |
|
* |
405 |
< |
* @return true if completed normally |
405 |
> |
* @return status on exit |
406 |
|
*/ |
407 |
< |
private boolean tryExec() { |
408 |
< |
try { // try block must contain only call to exec |
409 |
< |
if (!exec()) |
410 |
< |
return false; |
411 |
< |
} catch (Throwable rex) { |
412 |
< |
setDoneExceptionally(rex); |
413 |
< |
rethrowException(rex); |
414 |
< |
return false; // not reached |
407 |
> |
private int setExceptionalCompletion(Throwable ex) { |
408 |
> |
int h = System.identityHashCode(this); |
409 |
> |
ReentrantLock lock = exceptionTableLock; |
410 |
> |
lock.lock(); |
411 |
> |
try { |
412 |
> |
expungeStaleExceptions(); |
413 |
> |
ExceptionNode[] t = exceptionTable; |
414 |
> |
int i = h & (t.length - 1); |
415 |
> |
for (ExceptionNode e = t[i]; ; e = e.next) { |
416 |
> |
if (e == null) { |
417 |
> |
t[i] = new ExceptionNode(this, ex, t[i]); |
418 |
> |
break; |
419 |
> |
} |
420 |
> |
if (e.get() == this) // already present |
421 |
> |
break; |
422 |
> |
} |
423 |
> |
} finally { |
424 |
> |
lock.unlock(); |
425 |
|
} |
426 |
< |
setNormalCompletion(); |
449 |
< |
return true; |
426 |
> |
return setCompletion(EXCEPTIONAL); |
427 |
|
} |
428 |
|
|
429 |
|
/** |
430 |
< |
* Main execution method used by worker threads. Invokes |
454 |
< |
* base computation unless already complete. |
430 |
> |
* Removes exception node and clears status |
431 |
|
*/ |
432 |
< |
final void quietlyExec() { |
433 |
< |
if (status >= 0) { |
434 |
< |
try { |
435 |
< |
if (!exec()) |
436 |
< |
return; |
437 |
< |
} catch (Throwable rex) { |
438 |
< |
setDoneExceptionally(rex); |
439 |
< |
return; |
432 |
> |
private void clearExceptionalCompletion() { |
433 |
> |
int h = System.identityHashCode(this); |
434 |
> |
ReentrantLock lock = exceptionTableLock; |
435 |
> |
lock.lock(); |
436 |
> |
try { |
437 |
> |
ExceptionNode[] t = exceptionTable; |
438 |
> |
int i = h & (t.length - 1); |
439 |
> |
ExceptionNode e = t[i]; |
440 |
> |
ExceptionNode pred = null; |
441 |
> |
while (e != null) { |
442 |
> |
ExceptionNode next = e.next; |
443 |
> |
if (e.get() == this) { |
444 |
> |
if (pred == null) |
445 |
> |
t[i] = next; |
446 |
> |
else |
447 |
> |
pred.next = next; |
448 |
> |
break; |
449 |
> |
} |
450 |
> |
pred = e; |
451 |
> |
e = next; |
452 |
|
} |
453 |
< |
setNormalCompletion(); |
453 |
> |
expungeStaleExceptions(); |
454 |
> |
status = 0; |
455 |
> |
} finally { |
456 |
> |
lock.unlock(); |
457 |
|
} |
458 |
|
} |
459 |
|
|
460 |
|
/** |
461 |
< |
* Calls exec(), recording but not rethrowing exception. |
462 |
< |
* Caller should normally check status before calling. |
461 |
> |
* Returns a rethrowable exception for the given task, if |
462 |
> |
* available. To provide accurate stack traces, if the exception |
463 |
> |
* was not thrown by the current thread, we try to create a new |
464 |
> |
* exception of the same type as the one thrown, but with the |
465 |
> |
* recorded exception as its cause. If there is no such |
466 |
> |
* constructor, we instead try to use a no-arg constructor, |
467 |
> |
* followed by initCause, to the same effect. If none of these |
468 |
> |
* apply, or any fail due to other exceptions, we return the |
469 |
> |
* recorded exception, which is still correct, although it may |
470 |
> |
* contain a misleading stack trace. |
471 |
|
* |
472 |
< |
* @return true if completed normally |
472 |
> |
* @return the exception, or null if none |
473 |
|
*/ |
474 |
< |
private boolean tryQuietlyInvoke() { |
474 |
> |
private Throwable getThrowableException() { |
475 |
> |
if (status != EXCEPTIONAL) |
476 |
> |
return null; |
477 |
> |
int h = System.identityHashCode(this); |
478 |
> |
ExceptionNode e; |
479 |
> |
ReentrantLock lock = exceptionTableLock; |
480 |
> |
lock.lock(); |
481 |
|
try { |
482 |
< |
if (!exec()) |
483 |
< |
return false; |
484 |
< |
} catch (Throwable rex) { |
485 |
< |
setDoneExceptionally(rex); |
486 |
< |
return false; |
482 |
> |
expungeStaleExceptions(); |
483 |
> |
ExceptionNode[] t = exceptionTable; |
484 |
> |
e = t[h & (t.length - 1)]; |
485 |
> |
while (e != null && e.get() != this) |
486 |
> |
e = e.next; |
487 |
> |
} finally { |
488 |
> |
lock.unlock(); |
489 |
> |
} |
490 |
> |
Throwable ex; |
491 |
> |
if (e == null || (ex = e.ex) == null) |
492 |
> |
return null; |
493 |
> |
if (e.thrower != Thread.currentThread().getId()) { |
494 |
> |
Class ec = ex.getClass(); |
495 |
> |
try { |
496 |
> |
Constructor<?> noArgCtor = null; |
497 |
> |
Constructor<?>[] cs = ec.getConstructors();// public ctors only |
498 |
> |
for (int i = 0; i < cs.length; ++i) { |
499 |
> |
Constructor<?> c = cs[i]; |
500 |
> |
Class<?>[] ps = c.getParameterTypes(); |
501 |
> |
if (ps.length == 0) |
502 |
> |
noArgCtor = c; |
503 |
> |
else if (ps.length == 1 && ps[0] == Throwable.class) |
504 |
> |
return (Throwable)(c.newInstance(ex)); |
505 |
> |
} |
506 |
> |
if (noArgCtor != null) { |
507 |
> |
Throwable wx = (Throwable)(noArgCtor.newInstance()); |
508 |
> |
wx.initCause(ex); |
509 |
> |
return wx; |
510 |
> |
} |
511 |
> |
} catch (Exception ignore) { |
512 |
> |
} |
513 |
|
} |
514 |
< |
setNormalCompletion(); |
484 |
< |
return true; |
514 |
> |
return ex; |
515 |
|
} |
516 |
|
|
517 |
|
/** |
518 |
< |
* Cancels, ignoring any exceptions it throws. |
518 |
> |
* Poll stale refs and remove them. Call only while holding lock. |
519 |
|
*/ |
520 |
< |
final void cancelIgnoringExceptions() { |
521 |
< |
try { |
522 |
< |
cancel(false); |
523 |
< |
} catch (Throwable ignore) { |
520 |
> |
private static void expungeStaleExceptions() { |
521 |
> |
for (Object x; (x = exceptionTableRefQueue.poll()) != null;) { |
522 |
> |
if (x instanceof ExceptionNode) { |
523 |
> |
ForkJoinTask<?> key = ((ExceptionNode)x).get(); |
524 |
> |
ExceptionNode[] t = exceptionTable; |
525 |
> |
int i = System.identityHashCode(key) & (t.length - 1); |
526 |
> |
ExceptionNode e = t[i]; |
527 |
> |
ExceptionNode pred = null; |
528 |
> |
while (e != null) { |
529 |
> |
ExceptionNode next = e.next; |
530 |
> |
if (e == x) { |
531 |
> |
if (pred == null) |
532 |
> |
t[i] = next; |
533 |
> |
else |
534 |
> |
pred.next = next; |
535 |
> |
break; |
536 |
> |
} |
537 |
> |
pred = e; |
538 |
> |
e = next; |
539 |
> |
} |
540 |
> |
} |
541 |
|
} |
542 |
|
} |
543 |
|
|
544 |
|
/** |
545 |
< |
* Main implementation of helpJoin |
545 |
> |
* If lock is available, poll any stale refs and remove them. |
546 |
> |
* Called from ForkJoinPool when pools become quiescent. |
547 |
|
*/ |
548 |
< |
private int busyJoin(ForkJoinWorkerThread w) { |
549 |
< |
int s; |
550 |
< |
ForkJoinTask<?> t; |
551 |
< |
while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null) |
552 |
< |
t.quietlyExec(); |
553 |
< |
return (s >= 0) ? awaitDone(w, false) : s; // block if no work |
548 |
> |
static final void helpExpungeStaleExceptions() { |
549 |
> |
ReentrantLock lock = exceptionTableLock; |
550 |
> |
if (lock.tryLock()) { |
551 |
> |
try { |
552 |
> |
expungeStaleExceptions(); |
553 |
> |
} finally { |
554 |
> |
lock.unlock(); |
555 |
> |
} |
556 |
> |
} |
557 |
> |
} |
558 |
> |
|
559 |
> |
/** |
560 |
> |
* Report the result of invoke or join; called only upon |
561 |
> |
* non-normal return of internal versions. |
562 |
> |
*/ |
563 |
> |
private V reportResult() { |
564 |
> |
int s; Throwable ex; |
565 |
> |
if ((s = status) == CANCELLED) |
566 |
> |
throw new CancellationException(); |
567 |
> |
if (s == EXCEPTIONAL && (ex = getThrowableException()) != null) |
568 |
> |
UNSAFE.throwException(ex); |
569 |
> |
return getRawResult(); |
570 |
|
} |
571 |
|
|
572 |
|
// public methods |
575 |
|
* Arranges to asynchronously execute this task. While it is not |
576 |
|
* necessarily enforced, it is a usage error to fork a task more |
577 |
|
* than once unless it has completed and been reinitialized. |
578 |
+ |
* Subsequent modifications to the state of this task or any data |
579 |
+ |
* it operates on are not necessarily consistently observable by |
580 |
+ |
* any thread other than the one executing it unless preceded by a |
581 |
+ |
* call to {@link #join} or related methods, or a call to {@link |
582 |
+ |
* #isDone} returning {@code true}. |
583 |
|
* |
584 |
|
* <p>This method may be invoked only from within {@code |
585 |
< |
* ForkJoinTask} computations (as may be determined using method |
585 |
> |
* ForkJoinPool} computations (as may be determined using method |
586 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
587 |
|
* result in exceptions or errors, possibly including {@code |
588 |
|
* ClassCastException}. |
596 |
|
} |
597 |
|
|
598 |
|
/** |
599 |
< |
* Returns the result of the computation when it is ready. |
600 |
< |
* This method differs from {@link #get()} in that |
599 |
> |
* Returns the result of the computation when it {@link #isDone is |
600 |
> |
* done}. This method differs from {@link #get()} in that |
601 |
|
* abnormal completion results in {@code RuntimeException} or |
602 |
< |
* {@code Error}, not {@code ExecutionException}. |
602 |
> |
* {@code Error}, not {@code ExecutionException}, and that |
603 |
> |
* interrupts of the calling thread do <em>not</em> cause the |
604 |
> |
* method to abruptly return by throwing {@code |
605 |
> |
* InterruptedException}. |
606 |
|
* |
607 |
|
* @return the computed result |
608 |
|
*/ |
609 |
|
public final V join() { |
610 |
< |
ForkJoinWorkerThread w = getWorker(); |
611 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryExec()) |
612 |
< |
reportException(awaitDone(w, true)); |
613 |
< |
return getRawResult(); |
610 |
> |
if (doJoin() != NORMAL) |
611 |
> |
return reportResult(); |
612 |
> |
else |
613 |
> |
return getRawResult(); |
614 |
|
} |
615 |
|
|
616 |
|
/** |
617 |
|
* Commences performing this task, awaits its completion if |
618 |
< |
* necessary, and return its result, or throws an (unchecked) |
619 |
< |
* exception if the underlying computation did so. |
618 |
> |
* necessary, and returns its result, or throws an (unchecked) |
619 |
> |
* {@code RuntimeException} or {@code Error} if the underlying |
620 |
> |
* computation did so. |
621 |
|
* |
622 |
|
* @return the computed result |
623 |
|
*/ |
624 |
|
public final V invoke() { |
625 |
< |
if (status >= 0 && tryExec()) |
626 |
< |
return getRawResult(); |
625 |
> |
if (doInvoke() != NORMAL) |
626 |
> |
return reportResult(); |
627 |
|
else |
628 |
< |
return join(); |
628 |
> |
return getRawResult(); |
629 |
|
} |
630 |
|
|
631 |
|
/** |
632 |
|
* Forks the given tasks, returning when {@code isDone} holds for |
633 |
|
* each task or an (unchecked) exception is encountered, in which |
634 |
< |
* case the exception is rethrown. If more than one task |
634 |
> |
* case the exception is rethrown. If more than one task |
635 |
|
* encounters an exception, then this method throws any one of |
636 |
< |
* these exceptions. The individual status of each task may be |
637 |
< |
* checked using {@link #getException()} and related methods. |
636 |
> |
* these exceptions. If any task encounters an exception, the |
637 |
> |
* other may be cancelled. However, the execution status of |
638 |
> |
* individual tasks is not guaranteed upon exceptional return. The |
639 |
> |
* status of each task may be obtained using {@link |
640 |
> |
* #getException()} and related methods to check if they have been |
641 |
> |
* cancelled, completed normally or exceptionally, or left |
642 |
> |
* unprocessed. |
643 |
|
* |
644 |
|
* <p>This method may be invoked only from within {@code |
645 |
< |
* ForkJoinTask} computations (as may be determined using method |
645 |
> |
* ForkJoinPool} computations (as may be determined using method |
646 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
647 |
|
* result in exceptions or errors, possibly including {@code |
648 |
|
* ClassCastException}. |
660 |
|
/** |
661 |
|
* Forks the given tasks, returning when {@code isDone} holds for |
662 |
|
* each task or an (unchecked) exception is encountered, in which |
663 |
< |
* case the exception is rethrown. If any task encounters an |
664 |
< |
* exception, others may be, but are not guaranteed to be, |
665 |
< |
* cancelled. If more than one task encounters an exception, then |
666 |
< |
* this method throws any one of these exceptions. The individual |
667 |
< |
* status of each task may be checked using {@link #getException()} |
668 |
< |
* and related methods. |
663 |
> |
* case the exception is rethrown. If more than one task |
664 |
> |
* encounters an exception, then this method throws any one of |
665 |
> |
* these exceptions. If any task encounters an exception, others |
666 |
> |
* may be cancelled. However, the execution status of individual |
667 |
> |
* tasks is not guaranteed upon exceptional return. The status of |
668 |
> |
* each task may be obtained using {@link #getException()} and |
669 |
> |
* related methods to check if they have been cancelled, completed |
670 |
> |
* normally or exceptionally, or left unprocessed. |
671 |
|
* |
672 |
|
* <p>This method may be invoked only from within {@code |
673 |
< |
* ForkJoinTask} computations (as may be determined using method |
673 |
> |
* ForkJoinPool} computations (as may be determined using method |
674 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
675 |
|
* result in exceptions or errors, possibly including {@code |
676 |
|
* ClassCastException}. |
689 |
|
} |
690 |
|
else if (i != 0) |
691 |
|
t.fork(); |
692 |
< |
else { |
693 |
< |
t.quietlyInvoke(); |
614 |
< |
if (ex == null) |
615 |
< |
ex = t.getException(); |
616 |
< |
} |
692 |
> |
else if (t.doInvoke() < NORMAL && ex == null) |
693 |
> |
ex = t.getException(); |
694 |
|
} |
695 |
|
for (int i = 1; i <= last; ++i) { |
696 |
|
ForkJoinTask<?> t = tasks[i]; |
697 |
|
if (t != null) { |
698 |
|
if (ex != null) |
699 |
|
t.cancel(false); |
700 |
< |
else { |
701 |
< |
t.quietlyJoin(); |
625 |
< |
if (ex == null) |
626 |
< |
ex = t.getException(); |
627 |
< |
} |
700 |
> |
else if (t.doJoin() < NORMAL && ex == null) |
701 |
> |
ex = t.getException(); |
702 |
|
} |
703 |
|
} |
704 |
|
if (ex != null) |
705 |
< |
rethrowException(ex); |
705 |
> |
UNSAFE.throwException(ex); |
706 |
|
} |
707 |
|
|
708 |
|
/** |
709 |
|
* Forks all tasks in the specified collection, returning when |
710 |
|
* {@code isDone} holds for each task or an (unchecked) exception |
711 |
< |
* is encountered. If any task encounters an exception, others |
712 |
< |
* may be, but are not guaranteed to be, cancelled. If more than |
713 |
< |
* one task encounters an exception, then this method throws any |
714 |
< |
* one of these exceptions. The individual status of each task |
715 |
< |
* may be checked using {@link #getException()} and related |
716 |
< |
* methods. The behavior of this operation is undefined if the |
717 |
< |
* specified collection is modified while the operation is in |
718 |
< |
* progress. |
711 |
> |
* is encountered, in which case the exception is rethrown. If |
712 |
> |
* more than one task encounters an exception, then this method |
713 |
> |
* throws any one of these exceptions. If any task encounters an |
714 |
> |
* exception, others may be cancelled. However, the execution |
715 |
> |
* status of individual tasks is not guaranteed upon exceptional |
716 |
> |
* return. The status of each task may be obtained using {@link |
717 |
> |
* #getException()} and related methods to check if they have been |
718 |
> |
* cancelled, completed normally or exceptionally, or left |
719 |
> |
* unprocessed. |
720 |
|
* |
721 |
|
* <p>This method may be invoked only from within {@code |
722 |
< |
* ForkJoinTask} computations (as may be determined using method |
722 |
> |
* ForkJoinPool} computations (as may be determined using method |
723 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
724 |
|
* result in exceptions or errors, possibly including {@code |
725 |
|
* ClassCastException}. |
746 |
|
} |
747 |
|
else if (i != 0) |
748 |
|
t.fork(); |
749 |
< |
else { |
750 |
< |
t.quietlyInvoke(); |
676 |
< |
if (ex == null) |
677 |
< |
ex = t.getException(); |
678 |
< |
} |
749 |
> |
else if (t.doInvoke() < NORMAL && ex == null) |
750 |
> |
ex = t.getException(); |
751 |
|
} |
752 |
|
for (int i = 1; i <= last; ++i) { |
753 |
|
ForkJoinTask<?> t = ts.get(i); |
754 |
|
if (t != null) { |
755 |
|
if (ex != null) |
756 |
|
t.cancel(false); |
757 |
< |
else { |
758 |
< |
t.quietlyJoin(); |
687 |
< |
if (ex == null) |
688 |
< |
ex = t.getException(); |
689 |
< |
} |
757 |
> |
else if (t.doJoin() < NORMAL && ex == null) |
758 |
> |
ex = t.getException(); |
759 |
|
} |
760 |
|
} |
761 |
|
if (ex != null) |
762 |
< |
rethrowException(ex); |
762 |
> |
UNSAFE.throwException(ex); |
763 |
|
return tasks; |
764 |
|
} |
765 |
|
|
766 |
|
/** |
767 |
|
* Attempts to cancel execution of this task. This attempt will |
768 |
< |
* fail if the task has already completed, has already been |
769 |
< |
* cancelled, or could not be cancelled for some other reason. If |
770 |
< |
* successful, and this task has not started when cancel is |
771 |
< |
* called, execution of this task is suppressed, {@link |
772 |
< |
* #isCancelled} will report true, and {@link #join} will result |
773 |
< |
* in a {@code CancellationException} being thrown. |
768 |
> |
* fail if the task has already completed or could not be |
769 |
> |
* cancelled for some other reason. If successful, and this task |
770 |
> |
* has not started when {@code cancel} is called, execution of |
771 |
> |
* this task is suppressed. After this method returns |
772 |
> |
* successfully, unless there is an intervening call to {@link |
773 |
> |
* #reinitialize}, subsequent calls to {@link #isCancelled}, |
774 |
> |
* {@link #isDone}, and {@code cancel} will return {@code true} |
775 |
> |
* and calls to {@link #join} and related methods will result in |
776 |
> |
* {@code CancellationException}. |
777 |
|
* |
778 |
|
* <p>This method may be overridden in subclasses, but if so, must |
779 |
< |
* still ensure that these minimal properties hold. In particular, |
780 |
< |
* the {@code cancel} method itself must not throw exceptions. |
779 |
> |
* still ensure that these properties hold. In particular, the |
780 |
> |
* {@code cancel} method itself must not throw exceptions. |
781 |
|
* |
782 |
|
* <p>This method is designed to be invoked by <em>other</em> |
783 |
|
* tasks. To terminate the current task, you can just return or |
784 |
|
* throw an unchecked exception from its computation method, or |
785 |
|
* invoke {@link #completeExceptionally}. |
786 |
|
* |
787 |
< |
* @param mayInterruptIfRunning this value is ignored in the |
788 |
< |
* default implementation because tasks are not |
789 |
< |
* cancelled via interruption |
787 |
> |
* @param mayInterruptIfRunning this value has no effect in the |
788 |
> |
* default implementation because interrupts are not used to |
789 |
> |
* control cancellation. |
790 |
|
* |
791 |
|
* @return {@code true} if this task is now cancelled |
792 |
|
*/ |
793 |
|
public boolean cancel(boolean mayInterruptIfRunning) { |
794 |
< |
setCompletion(CANCELLED); |
723 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
794 |
> |
return setCompletion(CANCELLED) == CANCELLED; |
795 |
|
} |
796 |
|
|
797 |
|
/** |
798 |
< |
* Returns {@code true} if the computation performed by this task |
799 |
< |
* has completed (or has been cancelled). |
800 |
< |
* |
801 |
< |
* @return {@code true} if this computation has completed |
798 |
> |
* Cancels, ignoring any exceptions thrown by cancel. Used during |
799 |
> |
* worker and pool shutdown. Cancel is spec'ed not to throw any |
800 |
> |
* exceptions, but if it does anyway, we have no recourse during |
801 |
> |
* shutdown, so guard against this case. |
802 |
|
*/ |
803 |
+ |
final void cancelIgnoringExceptions() { |
804 |
+ |
try { |
805 |
+ |
cancel(false); |
806 |
+ |
} catch (Throwable ignore) { |
807 |
+ |
} |
808 |
+ |
} |
809 |
+ |
|
810 |
|
public final boolean isDone() { |
811 |
|
return status < 0; |
812 |
|
} |
813 |
|
|
736 |
– |
/** |
737 |
– |
* Returns {@code true} if this task was cancelled. |
738 |
– |
* |
739 |
– |
* @return {@code true} if this task was cancelled |
740 |
– |
*/ |
814 |
|
public final boolean isCancelled() { |
815 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
815 |
> |
return status == CANCELLED; |
816 |
|
} |
817 |
|
|
818 |
|
/** |
821 |
|
* @return {@code true} if this task threw an exception or was cancelled |
822 |
|
*/ |
823 |
|
public final boolean isCompletedAbnormally() { |
824 |
< |
return (status & COMPLETION_MASK) < NORMAL; |
824 |
> |
return status < NORMAL; |
825 |
|
} |
826 |
|
|
827 |
|
/** |
832 |
|
* exception and was not cancelled |
833 |
|
*/ |
834 |
|
public final boolean isCompletedNormally() { |
835 |
< |
return (status & COMPLETION_MASK) == NORMAL; |
763 |
< |
} |
764 |
< |
|
765 |
< |
/** |
766 |
< |
* Returns {@code true} if this task threw an exception. |
767 |
< |
* |
768 |
< |
* @return {@code true} if this task threw an exception |
769 |
< |
*/ |
770 |
< |
public final boolean isCompletedExceptionally() { |
771 |
< |
return (status & COMPLETION_MASK) == EXCEPTIONAL; |
835 |
> |
return status == NORMAL; |
836 |
|
} |
837 |
|
|
838 |
|
/** |
843 |
|
* @return the exception, or {@code null} if none |
844 |
|
*/ |
845 |
|
public final Throwable getException() { |
846 |
< |
int s = status & COMPLETION_MASK; |
847 |
< |
if (s >= NORMAL) |
848 |
< |
return null; |
849 |
< |
if (s == CANCELLED) |
786 |
< |
return new CancellationException(); |
787 |
< |
return exceptionMap.get(this); |
846 |
> |
int s = status; |
847 |
> |
return ((s >= NORMAL) ? null : |
848 |
> |
(s == CANCELLED) ? new CancellationException() : |
849 |
> |
getThrowableException()); |
850 |
|
} |
851 |
|
|
852 |
|
/** |
859 |
|
* overridable, but overridden versions must invoke {@code super} |
860 |
|
* implementation to maintain guarantees. |
861 |
|
* |
862 |
< |
* @param ex the exception to throw. If this exception is |
863 |
< |
* not a RuntimeException or Error, the actual exception thrown |
864 |
< |
* will be a RuntimeException with cause ex. |
862 |
> |
* @param ex the exception to throw. If this exception is not a |
863 |
> |
* {@code RuntimeException} or {@code Error}, the actual exception |
864 |
> |
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
865 |
|
*/ |
866 |
|
public void completeExceptionally(Throwable ex) { |
867 |
< |
setDoneExceptionally((ex instanceof RuntimeException) || |
868 |
< |
(ex instanceof Error) ? ex : |
869 |
< |
new RuntimeException(ex)); |
867 |
> |
setExceptionalCompletion((ex instanceof RuntimeException) || |
868 |
> |
(ex instanceof Error) ? ex : |
869 |
> |
new RuntimeException(ex)); |
870 |
|
} |
871 |
|
|
872 |
|
/** |
873 |
|
* Completes this task, and if not already aborted or cancelled, |
874 |
< |
* returning a {@code null} result upon {@code join} and related |
875 |
< |
* operations. This method may be used to provide results for |
876 |
< |
* asynchronous tasks, or to provide alternative handling for |
877 |
< |
* tasks that would not otherwise complete normally. Its use in |
878 |
< |
* other situations is discouraged. This method is |
879 |
< |
* overridable, but overridden versions must invoke {@code super} |
880 |
< |
* implementation to maintain guarantees. |
874 |
> |
* returning the given value as the result of subsequent |
875 |
> |
* invocations of {@code join} and related operations. This method |
876 |
> |
* may be used to provide results for asynchronous tasks, or to |
877 |
> |
* provide alternative handling for tasks that would not otherwise |
878 |
> |
* complete normally. Its use in other situations is |
879 |
> |
* discouraged. This method is overridable, but overridden |
880 |
> |
* versions must invoke {@code super} implementation to maintain |
881 |
> |
* guarantees. |
882 |
|
* |
883 |
|
* @param value the result value for this task |
884 |
|
*/ |
886 |
|
try { |
887 |
|
setRawResult(value); |
888 |
|
} catch (Throwable rex) { |
889 |
< |
setDoneExceptionally(rex); |
889 |
> |
setExceptionalCompletion(rex); |
890 |
|
return; |
891 |
|
} |
892 |
< |
setNormalCompletion(); |
830 |
< |
} |
831 |
< |
|
832 |
< |
public final V get() throws InterruptedException, ExecutionException { |
833 |
< |
ForkJoinWorkerThread w = getWorker(); |
834 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
835 |
< |
awaitDone(w, true); |
836 |
< |
return reportFutureResult(); |
837 |
< |
} |
838 |
< |
|
839 |
< |
public final V get(long timeout, TimeUnit unit) |
840 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
841 |
< |
long nanos = unit.toNanos(timeout); |
842 |
< |
ForkJoinWorkerThread w = getWorker(); |
843 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
844 |
< |
awaitDone(w, nanos); |
845 |
< |
return reportTimedFutureResult(); |
892 |
> |
setCompletion(NORMAL); |
893 |
|
} |
894 |
|
|
895 |
|
/** |
896 |
< |
* Possibly executes other tasks until this task is ready, then |
897 |
< |
* returns the result of the computation. This method may be more |
851 |
< |
* efficient than {@code join}, but is only applicable when |
852 |
< |
* there are no potential dependencies between continuation of the |
853 |
< |
* current task and that of any other task that might be executed |
854 |
< |
* while helping. (This usually holds for pure divide-and-conquer |
855 |
< |
* tasks). |
856 |
< |
* |
857 |
< |
* <p>This method may be invoked only from within {@code |
858 |
< |
* ForkJoinTask} computations (as may be determined using method |
859 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
860 |
< |
* result in exceptions or errors, possibly including {@code |
861 |
< |
* ClassCastException}. |
896 |
> |
* Waits if necessary for the computation to complete, and then |
897 |
> |
* retrieves its result. |
898 |
|
* |
899 |
|
* @return the computed result |
900 |
+ |
* @throws CancellationException if the computation was cancelled |
901 |
+ |
* @throws ExecutionException if the computation threw an |
902 |
+ |
* exception |
903 |
+ |
* @throws InterruptedException if the current thread is not a |
904 |
+ |
* member of a ForkJoinPool and was interrupted while waiting |
905 |
|
*/ |
906 |
< |
public final V helpJoin() { |
907 |
< |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) Thread.currentThread(); |
908 |
< |
if (status < 0 || !w.unpushTask(this) || !tryExec()) |
909 |
< |
reportException(busyJoin(w)); |
906 |
> |
public final V get() throws InterruptedException, ExecutionException { |
907 |
> |
int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ? |
908 |
> |
doJoin() : externalInterruptibleAwaitDone(0L); |
909 |
> |
Throwable ex; |
910 |
> |
if (s == CANCELLED) |
911 |
> |
throw new CancellationException(); |
912 |
> |
if (s == EXCEPTIONAL && (ex = getThrowableException()) != null) |
913 |
> |
throw new ExecutionException(ex); |
914 |
|
return getRawResult(); |
915 |
|
} |
916 |
|
|
917 |
|
/** |
918 |
< |
* Possibly executes other tasks until this task is ready. This |
919 |
< |
* method may be useful when processing collections of tasks when |
875 |
< |
* some have been cancelled or otherwise known to have aborted. |
918 |
> |
* Waits if necessary for at most the given time for the computation |
919 |
> |
* to complete, and then retrieves its result, if available. |
920 |
|
* |
921 |
< |
* <p>This method may be invoked only from within {@code |
922 |
< |
* ForkJoinTask} computations (as may be determined using method |
923 |
< |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
924 |
< |
* result in exceptions or errors, possibly including {@code |
925 |
< |
* ClassCastException}. |
921 |
> |
* @param timeout the maximum time to wait |
922 |
> |
* @param unit the time unit of the timeout argument |
923 |
> |
* @return the computed result |
924 |
> |
* @throws CancellationException if the computation was cancelled |
925 |
> |
* @throws ExecutionException if the computation threw an |
926 |
> |
* exception |
927 |
> |
* @throws InterruptedException if the current thread is not a |
928 |
> |
* member of a ForkJoinPool and was interrupted while waiting |
929 |
> |
* @throws TimeoutException if the wait timed out |
930 |
|
*/ |
931 |
< |
public final void quietlyHelpJoin() { |
932 |
< |
if (status >= 0) { |
933 |
< |
ForkJoinWorkerThread w = |
934 |
< |
(ForkJoinWorkerThread) Thread.currentThread(); |
935 |
< |
if (!w.unpushTask(this) || !tryQuietlyInvoke()) |
936 |
< |
busyJoin(w); |
931 |
> |
public final V get(long timeout, TimeUnit unit) |
932 |
> |
throws InterruptedException, ExecutionException, TimeoutException { |
933 |
> |
Thread t = Thread.currentThread(); |
934 |
> |
if (t instanceof ForkJoinWorkerThread) { |
935 |
> |
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
936 |
> |
long nanos = unit.toNanos(timeout); |
937 |
> |
if (status >= 0) { |
938 |
> |
boolean completed = false; |
939 |
> |
if (w.unpushTask(this)) { |
940 |
> |
try { |
941 |
> |
completed = exec(); |
942 |
> |
} catch (Throwable rex) { |
943 |
> |
setExceptionalCompletion(rex); |
944 |
> |
} |
945 |
> |
} |
946 |
> |
if (completed) |
947 |
> |
setCompletion(NORMAL); |
948 |
> |
else if (status >= 0 && nanos > 0) |
949 |
> |
w.pool.timedAwaitJoin(this, nanos); |
950 |
> |
} |
951 |
|
} |
952 |
+ |
else { |
953 |
+ |
long millis = unit.toMillis(timeout); |
954 |
+ |
if (millis > 0) |
955 |
+ |
externalInterruptibleAwaitDone(millis); |
956 |
+ |
} |
957 |
+ |
int s = status; |
958 |
+ |
if (s != NORMAL) { |
959 |
+ |
Throwable ex; |
960 |
+ |
if (s == CANCELLED) |
961 |
+ |
throw new CancellationException(); |
962 |
+ |
if (s != EXCEPTIONAL) |
963 |
+ |
throw new TimeoutException(); |
964 |
+ |
if ((ex = getThrowableException()) != null) |
965 |
+ |
throw new ExecutionException(ex); |
966 |
+ |
} |
967 |
+ |
return getRawResult(); |
968 |
|
} |
969 |
|
|
970 |
|
/** |
971 |
< |
* Joins this task, without returning its result or throwing an |
971 |
> |
* Joins this task, without returning its result or throwing its |
972 |
|
* exception. This method may be useful when processing |
973 |
|
* collections of tasks when some have been cancelled or otherwise |
974 |
|
* known to have aborted. |
975 |
|
*/ |
976 |
|
public final void quietlyJoin() { |
977 |
< |
if (status >= 0) { |
900 |
< |
ForkJoinWorkerThread w = getWorker(); |
901 |
< |
if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke()) |
902 |
< |
awaitDone(w, true); |
903 |
< |
} |
977 |
> |
doJoin(); |
978 |
|
} |
979 |
|
|
980 |
|
/** |
981 |
|
* Commences performing this task and awaits its completion if |
982 |
< |
* necessary, without returning its result or throwing an |
983 |
< |
* exception. This method may be useful when processing |
910 |
< |
* collections of tasks when some have been cancelled or otherwise |
911 |
< |
* known to have aborted. |
982 |
> |
* necessary, without returning its result or throwing its |
983 |
> |
* exception. |
984 |
|
*/ |
985 |
|
public final void quietlyInvoke() { |
986 |
< |
if (status >= 0 && !tryQuietlyInvoke()) |
915 |
< |
quietlyJoin(); |
986 |
> |
doInvoke(); |
987 |
|
} |
988 |
|
|
989 |
|
/** |
994 |
|
* processed. |
995 |
|
* |
996 |
|
* <p>This method may be invoked only from within {@code |
997 |
< |
* ForkJoinTask} computations (as may be determined using method |
997 |
> |
* ForkJoinPool} computations (as may be determined using method |
998 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
999 |
|
* result in exceptions or errors, possibly including {@code |
1000 |
|
* ClassCastException}. |
1013 |
|
* under any other usage conditions are not guaranteed. |
1014 |
|
* This method may be useful when executing |
1015 |
|
* pre-constructed trees of subtasks in loops. |
1016 |
+ |
* |
1017 |
+ |
* <p>Upon completion of this method, {@code isDone()} reports |
1018 |
+ |
* {@code false}, and {@code getException()} reports {@code |
1019 |
+ |
* null}. However, the value returned by {@code getRawResult} is |
1020 |
+ |
* unaffected. To clear this value, you can invoke {@code |
1021 |
+ |
* setRawResult(null)}. |
1022 |
|
*/ |
1023 |
|
public void reinitialize() { |
1024 |
< |
if ((status & COMPLETION_MASK) == EXCEPTIONAL) |
1025 |
< |
exceptionMap.remove(this); |
1026 |
< |
status = 0; |
1024 |
> |
if (status == EXCEPTIONAL) |
1025 |
> |
clearExceptionalCompletion(); |
1026 |
> |
else |
1027 |
> |
status = 0; |
1028 |
|
} |
1029 |
|
|
1030 |
|
/** |
1041 |
|
} |
1042 |
|
|
1043 |
|
/** |
1044 |
< |
* Returns {@code true} if the current thread is executing as a |
1045 |
< |
* ForkJoinPool computation. |
1044 |
> |
* Returns {@code true} if the current thread is a {@link |
1045 |
> |
* ForkJoinWorkerThread} executing as a ForkJoinPool computation. |
1046 |
|
* |
1047 |
< |
* @return {@code true} if the current thread is executing as a |
1048 |
< |
* ForkJoinPool computation, or false otherwise |
1047 |
> |
* @return {@code true} if the current thread is a {@link |
1048 |
> |
* ForkJoinWorkerThread} executing as a ForkJoinPool computation, |
1049 |
> |
* or {@code false} otherwise |
1050 |
|
*/ |
1051 |
|
public static boolean inForkJoinPool() { |
1052 |
|
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
1061 |
|
* were not, stolen. |
1062 |
|
* |
1063 |
|
* <p>This method may be invoked only from within {@code |
1064 |
< |
* ForkJoinTask} computations (as may be determined using method |
1064 |
> |
* ForkJoinPool} computations (as may be determined using method |
1065 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1066 |
|
* result in exceptions or errors, possibly including {@code |
1067 |
|
* ClassCastException}. |
1080 |
|
* fork other tasks. |
1081 |
|
* |
1082 |
|
* <p>This method may be invoked only from within {@code |
1083 |
< |
* ForkJoinTask} computations (as may be determined using method |
1083 |
> |
* ForkJoinPool} computations (as may be determined using method |
1084 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1085 |
|
* result in exceptions or errors, possibly including {@code |
1086 |
|
* ClassCastException}. |
1103 |
|
* exceeded. |
1104 |
|
* |
1105 |
|
* <p>This method may be invoked only from within {@code |
1106 |
< |
* ForkJoinTask} computations (as may be determined using method |
1106 |
> |
* ForkJoinPool} computations (as may be determined using method |
1107 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1108 |
|
* result in exceptions or errors, possibly including {@code |
1109 |
|
* ClassCastException}. |
1161 |
|
* otherwise. |
1162 |
|
* |
1163 |
|
* <p>This method may be invoked only from within {@code |
1164 |
< |
* ForkJoinTask} computations (as may be determined using method |
1164 |
> |
* ForkJoinPool} computations (as may be determined using method |
1165 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1166 |
|
* result in exceptions or errors, possibly including {@code |
1167 |
|
* ClassCastException}. |
1180 |
|
* be useful otherwise. |
1181 |
|
* |
1182 |
|
* <p>This method may be invoked only from within {@code |
1183 |
< |
* ForkJoinTask} computations (as may be determined using method |
1183 |
> |
* ForkJoinPool} computations (as may be determined using method |
1184 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1185 |
|
* result in exceptions or errors, possibly including {@code |
1186 |
|
* ClassCastException}. |
1203 |
|
* otherwise. |
1204 |
|
* |
1205 |
|
* <p>This method may be invoked only from within {@code |
1206 |
< |
* ForkJoinTask} computations (as may be determined using method |
1206 |
> |
* ForkJoinPool} computations (as may be determined using method |
1207 |
|
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1208 |
|
* result in exceptions or errors, possibly including {@code |
1209 |
|
* ClassCastException}. |
1313 |
|
private static final long serialVersionUID = -7721805057305804111L; |
1314 |
|
|
1315 |
|
/** |
1316 |
< |
* Save the state to a stream. |
1316 |
> |
* Saves the state to a stream (that is, serializes it). |
1317 |
|
* |
1318 |
|
* @serialData the current run status and the exception thrown |
1319 |
|
* during execution, or {@code null} if none |
1326 |
|
} |
1327 |
|
|
1328 |
|
/** |
1329 |
< |
* Reconstitute the instance from a stream. |
1329 |
> |
* Reconstitutes the instance from a stream (that is, deserializes it). |
1330 |
|
* |
1331 |
|
* @param s the stream |
1332 |
|
*/ |
1333 |
|
private void readObject(java.io.ObjectInputStream s) |
1334 |
|
throws java.io.IOException, ClassNotFoundException { |
1335 |
|
s.defaultReadObject(); |
1257 |
– |
status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts |
1258 |
– |
status |= EXTERNAL_SIGNAL; // conservatively set external signal |
1336 |
|
Object ex = s.readObject(); |
1337 |
|
if (ex != null) |
1338 |
< |
setDoneExceptionally((Throwable) ex); |
1338 |
> |
setExceptionalCompletion((Throwable)ex); |
1339 |
|
} |
1340 |
|
|
1341 |
|
// Unsafe mechanics |
1342 |
< |
|
1343 |
< |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
1344 |
< |
private static final long statusOffset = |
1345 |
< |
objectFieldOffset("status", ForkJoinTask.class); |
1346 |
< |
|
1347 |
< |
private static long objectFieldOffset(String field, Class<?> klazz) { |
1342 |
> |
private static final sun.misc.Unsafe UNSAFE; |
1343 |
> |
private static final long statusOffset; |
1344 |
> |
static { |
1345 |
> |
exceptionTableLock = new ReentrantLock(); |
1346 |
> |
exceptionTableRefQueue = new ReferenceQueue<Object>(); |
1347 |
> |
exceptionTable = new ExceptionNode[EXCEPTION_MAP_CAPACITY]; |
1348 |
|
try { |
1349 |
< |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
1350 |
< |
} catch (NoSuchFieldException e) { |
1351 |
< |
// Convert Exception to corresponding Error |
1352 |
< |
NoSuchFieldError error = new NoSuchFieldError(field); |
1353 |
< |
error.initCause(e); |
1277 |
< |
throw error; |
1349 |
> |
UNSAFE = getUnsafe(); |
1350 |
> |
statusOffset = UNSAFE.objectFieldOffset |
1351 |
> |
(ForkJoinTask.class.getDeclaredField("status")); |
1352 |
> |
} catch (Exception e) { |
1353 |
> |
throw new Error(e); |
1354 |
|
} |
1355 |
|
} |
1356 |
|
|