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jsr166 |
1.1 |
/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
3 |
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* Expert Group and released to the public domain, as explained at |
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jsr166 |
1.48 |
* http://creativecommons.org/publicdomain/zero/1.0/ |
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jsr166 |
1.1 |
*/ |
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package java.util.concurrent; |
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import java.io.Serializable; |
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dl |
1.109 |
import java.lang.invoke.MethodHandles; |
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import java.lang.invoke.VarHandle; |
12 |
jsr166 |
1.90 |
import java.lang.ref.ReferenceQueue; |
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import java.lang.ref.WeakReference; |
14 |
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import java.lang.reflect.Constructor; |
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jsr166 |
1.1 |
import java.util.Collection; |
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import java.util.List; |
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jsr166 |
1.7 |
import java.util.RandomAccess; |
18 |
dl |
1.45 |
import java.util.concurrent.locks.ReentrantLock; |
19 |
jsr166 |
1.1 |
|
20 |
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/** |
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jsr166 |
1.6 |
* Abstract base class for tasks that run within a {@link ForkJoinPool}. |
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* A {@code ForkJoinTask} is a thread-like entity that is much |
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jsr166 |
1.1 |
* lighter weight than a normal thread. Huge numbers of tasks and |
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* subtasks may be hosted by a small number of actual threads in a |
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* ForkJoinPool, at the price of some usage limitations. |
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* |
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dl |
1.64 |
* <p>A "main" {@code ForkJoinTask} begins execution when it is |
28 |
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* explicitly submitted to a {@link ForkJoinPool}, or, if not already |
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* engaged in a ForkJoin computation, commenced in the {@link |
30 |
dl |
1.67 |
* ForkJoinPool#commonPool()} via {@link #fork}, {@link #invoke}, or |
31 |
dl |
1.64 |
* related methods. Once started, it will usually in turn start other |
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* subtasks. As indicated by the name of this class, many programs |
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* using {@code ForkJoinTask} employ only methods {@link #fork} and |
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* {@link #join}, or derivatives such as {@link |
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jsr166 |
1.27 |
* #invokeAll(ForkJoinTask...) invokeAll}. However, this class also |
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* provides a number of other methods that can come into play in |
37 |
dl |
1.64 |
* advanced usages, as well as extension mechanics that allow support |
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* of new forms of fork/join processing. |
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jsr166 |
1.1 |
* |
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jsr166 |
1.6 |
* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}. |
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* The efficiency of {@code ForkJoinTask}s stems from a set of |
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* restrictions (that are only partially statically enforceable) |
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dl |
1.54 |
* reflecting their main use as computational tasks calculating pure |
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* functions or operating on purely isolated objects. The primary |
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* coordination mechanisms are {@link #fork}, that arranges |
46 |
jsr166 |
1.6 |
* asynchronous execution, and {@link #join}, that doesn't proceed |
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* until the task's result has been computed. Computations should |
48 |
dl |
1.54 |
* ideally avoid {@code synchronized} methods or blocks, and should |
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* minimize other blocking synchronization apart from joining other |
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* tasks or using synchronizers such as Phasers that are advertised to |
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* cooperate with fork/join scheduling. Subdividable tasks should also |
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jsr166 |
1.68 |
* not perform blocking I/O, and should ideally access variables that |
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dl |
1.54 |
* are completely independent of those accessed by other running |
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* tasks. These guidelines are loosely enforced by not permitting |
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* checked exceptions such as {@code IOExceptions} to be |
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* thrown. However, computations may still encounter unchecked |
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* exceptions, that are rethrown to callers attempting to join |
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* them. These exceptions may additionally include {@link |
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* RejectedExecutionException} stemming from internal resource |
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* exhaustion, such as failure to allocate internal task |
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* queues. Rethrown exceptions behave in the same way as regular |
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* exceptions, but, when possible, contain stack traces (as displayed |
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* for example using {@code ex.printStackTrace()}) of both the thread |
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* that initiated the computation as well as the thread actually |
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* encountering the exception; minimally only the latter. |
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* |
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* <p>It is possible to define and use ForkJoinTasks that may block, |
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jsr166 |
1.110 |
* but doing so requires three further considerations: (1) Completion |
69 |
dl |
1.54 |
* of few if any <em>other</em> tasks should be dependent on a task |
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jsr166 |
1.68 |
* that blocks on external synchronization or I/O. Event-style async |
71 |
dl |
1.63 |
* tasks that are never joined (for example, those subclassing {@link |
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* CountedCompleter}) often fall into this category. (2) To minimize |
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* resource impact, tasks should be small; ideally performing only the |
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* (possibly) blocking action. (3) Unless the {@link |
75 |
dl |
1.54 |
* ForkJoinPool.ManagedBlocker} API is used, or the number of possibly |
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* blocked tasks is known to be less than the pool's {@link |
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* ForkJoinPool#getParallelism} level, the pool cannot guarantee that |
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* enough threads will be available to ensure progress or good |
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* performance. |
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jsr166 |
1.1 |
* |
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* <p>The primary method for awaiting completion and extracting |
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* results of a task is {@link #join}, but there are several variants: |
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* The {@link Future#get} methods support interruptible and/or timed |
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* waits for completion and report results using {@code Future} |
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dl |
1.16 |
* conventions. Method {@link #invoke} is semantically |
86 |
jsr166 |
1.8 |
* equivalent to {@code fork(); join()} but always attempts to begin |
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* execution in the current thread. The "<em>quiet</em>" forms of |
88 |
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* these methods do not extract results or report exceptions. These |
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jsr166 |
1.1 |
* may be useful when a set of tasks are being executed, and you need |
90 |
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* to delay processing of results or exceptions until all complete. |
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* Method {@code invokeAll} (available in multiple versions) |
92 |
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* performs the most common form of parallel invocation: forking a set |
93 |
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* of tasks and joining them all. |
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* |
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jsr166 |
1.57 |
* <p>In the most typical usages, a fork-join pair act like a call |
96 |
dl |
1.54 |
* (fork) and return (join) from a parallel recursive function. As is |
97 |
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* the case with other forms of recursive calls, returns (joins) |
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* should be performed innermost-first. For example, {@code a.fork(); |
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* b.fork(); b.join(); a.join();} is likely to be substantially more |
100 |
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* efficient than joining {@code a} before {@code b}. |
101 |
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* |
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jsr166 |
1.8 |
* <p>The execution status of tasks may be queried at several levels |
103 |
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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); |
105 |
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* {@link #isCompletedNormally} is true if a task completed without |
106 |
jsr166 |
1.10 |
* cancellation or encountering an exception; {@link #isCancelled} is |
107 |
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* true if the task was cancelled (in which case {@link #getException} |
108 |
jsr166 |
1.115 |
* returns a {@link CancellationException}); and |
109 |
jsr166 |
1.10 |
* {@link #isCompletedAbnormally} is true if a task was either |
110 |
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* cancelled or encountered an exception, in which case {@link |
111 |
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* #getException} will return either the encountered exception or |
112 |
jsr166 |
1.115 |
* {@link CancellationException}. |
113 |
jsr166 |
1.8 |
* |
114 |
jsr166 |
1.6 |
* <p>The ForkJoinTask class is not usually directly subclassed. |
115 |
jsr166 |
1.1 |
* Instead, you subclass one of the abstract classes that support a |
116 |
jsr166 |
1.6 |
* particular style of fork/join processing, typically {@link |
117 |
dl |
1.62 |
* RecursiveAction} for most computations that do not return results, |
118 |
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* {@link RecursiveTask} for those that do, and {@link |
119 |
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* CountedCompleter} for those in which completed actions trigger |
120 |
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* other actions. Normally, a concrete ForkJoinTask subclass declares |
121 |
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* fields comprising its parameters, established in a constructor, and |
122 |
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* then defines a {@code compute} method that somehow uses the control |
123 |
dl |
1.64 |
* methods supplied by this base class. |
124 |
jsr166 |
1.1 |
* |
125 |
dl |
1.38 |
* <p>Method {@link #join} and its variants are appropriate for use |
126 |
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* only when completion dependencies are acyclic; that is, the |
127 |
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* parallel computation can be described as a directed acyclic graph |
128 |
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* (DAG). Otherwise, executions may encounter a form of deadlock as |
129 |
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* tasks cyclically wait for each other. However, this framework |
130 |
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* supports other methods and techniques (for example the use of |
131 |
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* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that |
132 |
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* may be of use in constructing custom subclasses for problems that |
133 |
jsr166 |
1.79 |
* are not statically structured as DAGs. To support such usages, a |
134 |
dl |
1.63 |
* ForkJoinTask may be atomically <em>tagged</em> with a {@code short} |
135 |
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* value using {@link #setForkJoinTaskTag} or {@link |
136 |
dl |
1.60 |
* #compareAndSetForkJoinTaskTag} and checked using {@link |
137 |
dl |
1.63 |
* #getForkJoinTaskTag}. The ForkJoinTask implementation does not use |
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* these {@code protected} methods or tags for any purpose, but they |
139 |
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* may be of use in the construction of specialized subclasses. For |
140 |
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* example, parallel graph traversals can use the supplied methods to |
141 |
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* avoid revisiting nodes/tasks that have already been processed. |
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* (Method names for tagging are bulky in part to encourage definition |
143 |
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* of methods that reflect their usage patterns.) |
144 |
dl |
1.38 |
* |
145 |
jsr166 |
1.7 |
* <p>Most base support methods are {@code final}, to prevent |
146 |
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* overriding of implementations that are intrinsically tied to the |
147 |
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* underlying lightweight task scheduling framework. Developers |
148 |
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* creating new basic styles of fork/join processing should minimally |
149 |
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* implement {@code protected} methods {@link #exec}, {@link |
150 |
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* #setRawResult}, and {@link #getRawResult}, while also introducing |
151 |
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* an abstract computational method that can be implemented in its |
152 |
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* subclasses, possibly relying on other {@code protected} methods |
153 |
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* provided by this class. |
154 |
jsr166 |
1.1 |
* |
155 |
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* <p>ForkJoinTasks should perform relatively small amounts of |
156 |
jsr166 |
1.7 |
* computation. Large tasks should be split into smaller subtasks, |
157 |
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* usually via recursive decomposition. As a very rough rule of thumb, |
158 |
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* a task should perform more than 100 and less than 10000 basic |
159 |
dl |
1.40 |
* computational steps, and should avoid indefinite looping. If tasks |
160 |
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* are too big, then parallelism cannot improve throughput. If too |
161 |
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* small, then memory and internal task maintenance overhead may |
162 |
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* overwhelm processing. |
163 |
jsr166 |
1.1 |
* |
164 |
jsr166 |
1.8 |
* <p>This class provides {@code adapt} methods for {@link Runnable} |
165 |
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* and {@link Callable}, that may be of use when mixing execution of |
166 |
dl |
1.16 |
* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are |
167 |
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* of this form, consider using a pool constructed in <em>asyncMode</em>. |
168 |
jsr166 |
1.6 |
* |
169 |
jsr166 |
1.7 |
* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
170 |
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* used in extensions such as remote execution frameworks. It is |
171 |
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* sensible to serialize tasks only before or after, but not during, |
172 |
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* execution. Serialization is not relied on during execution itself. |
173 |
jsr166 |
1.1 |
* |
174 |
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* @since 1.7 |
175 |
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* @author Doug Lea |
176 |
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*/ |
177 |
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public abstract class ForkJoinTask<V> implements Future<V>, Serializable { |
178 |
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179 |
dl |
1.13 |
/* |
180 |
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* See the internal documentation of class ForkJoinPool for a |
181 |
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* general implementation overview. ForkJoinTasks are mainly |
182 |
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* responsible for maintaining their "status" field amidst relays |
183 |
jsr166 |
1.51 |
* to methods in ForkJoinWorkerThread and ForkJoinPool. |
184 |
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* |
185 |
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* The methods of this class are more-or-less layered into |
186 |
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* (1) basic status maintenance |
187 |
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* (2) execution and awaiting completion |
188 |
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* (3) user-level methods that additionally report results. |
189 |
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* This is sometimes hard to see because this file orders exported |
190 |
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* methods in a way that flows well in javadocs. |
191 |
dl |
1.13 |
*/ |
192 |
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|
193 |
dl |
1.118 |
/** |
194 |
dl |
1.17 |
* The status field holds run control status bits packed into a |
195 |
dl |
1.118 |
* single int to ensure atomicity. Status is initially zero, and |
196 |
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* takes on nonnegative values until completed, upon which it |
197 |
dl |
1.119 |
* holds (sign bit) DONE, possibly with ABNORMAL (cancelled or |
198 |
dl |
1.118 |
* exceptional) and THROWN (in which case an exception has been |
199 |
dl |
1.119 |
* stored). Tasks with dependent blocked waiting joiners have the |
200 |
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* SIGNAL bit set. Completion of a task with SIGNAL set awakens |
201 |
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* any waiters via notifyAll. (Waiters also help signal others |
202 |
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* upon completion.) |
203 |
dl |
1.60 |
* |
204 |
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* These control bits occupy only (some of) the upper half (16 |
205 |
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* bits) of status field. The lower bits are used for user-defined |
206 |
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* tags. |
207 |
jsr166 |
1.1 |
*/ |
208 |
dl |
1.118 |
volatile int status; // accessed directly by pool and workers |
209 |
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210 |
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private static final int DONE = 1 << 31; // must be negative |
211 |
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private static final int ABNORMAL = 1 << 18; // set atomically with DONE |
212 |
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private static final int THROWN = 1 << 17; // set atomically with ABNORMAL |
213 |
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private static final int SIGNAL = 1 << 16; // true if joiner waiting |
214 |
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private static final int SMASK = 0xffff; // short bits for tags |
215 |
dl |
1.17 |
|
216 |
dl |
1.118 |
static boolean isExceptionalStatus(int s) { // needed by subclasses |
217 |
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return (s & THROWN) != 0; |
218 |
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} |
219 |
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220 |
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/** |
221 |
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* Sets DONE status and wakes up threads waiting to join this task. |
222 |
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* |
223 |
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* @return status on exit |
224 |
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*/ |
225 |
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private int setDone() { |
226 |
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int s; |
227 |
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if (((s = (int)STATUS.getAndBitwiseOr(this, DONE)) & SIGNAL) != 0) |
228 |
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synchronized (this) { notifyAll(); } |
229 |
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return s | DONE; |
230 |
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} |
231 |
jsr166 |
1.1 |
|
232 |
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/** |
233 |
dl |
1.118 |
* Marks cancelled or exceptional completion unless already done. |
234 |
dl |
1.13 |
* |
235 |
dl |
1.118 |
* @param completion must be DONE | ABNORMAL, ORed with THROWN if exceptional |
236 |
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* @return status on exit |
237 |
jsr166 |
1.1 |
*/ |
238 |
dl |
1.118 |
private int abnormalCompletion(int completion) { |
239 |
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for (int s, ns;;) { |
240 |
dl |
1.45 |
if ((s = status) < 0) |
241 |
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return s; |
242 |
dl |
1.118 |
else if (STATUS.weakCompareAndSet(this, s, ns = s | completion)) { |
243 |
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if ((s & SIGNAL) != 0) |
244 |
dl |
1.13 |
synchronized (this) { notifyAll(); } |
245 |
dl |
1.118 |
return ns; |
246 |
dl |
1.13 |
} |
247 |
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} |
248 |
jsr166 |
1.1 |
} |
249 |
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|
250 |
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/** |
251 |
dl |
1.54 |
* Primary execution method for stolen tasks. Unless done, calls |
252 |
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* exec and records status if completed, but doesn't wait for |
253 |
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* completion otherwise. |
254 |
jsr166 |
1.24 |
* |
255 |
dl |
1.54 |
* @return status on exit from this method |
256 |
jsr166 |
1.1 |
*/ |
257 |
dl |
1.54 |
final int doExec() { |
258 |
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int s; boolean completed; |
259 |
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if ((s = status) >= 0) { |
260 |
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try { |
261 |
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completed = exec(); |
262 |
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} catch (Throwable rex) { |
263 |
dl |
1.118 |
completed = false; |
264 |
|
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s = setExceptionalCompletion(rex); |
265 |
dl |
1.54 |
} |
266 |
dl |
1.60 |
if (completed) |
267 |
dl |
1.118 |
s = setDone(); |
268 |
jsr166 |
1.1 |
} |
269 |
dl |
1.54 |
return s; |
270 |
jsr166 |
1.1 |
} |
271 |
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|
272 |
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/** |
273 |
dl |
1.87 |
* If not done, sets SIGNAL status and performs Object.wait(timeout). |
274 |
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* This task may or may not be done on exit. Ignores interrupts. |
275 |
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* |
276 |
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* @param timeout using Object.wait conventions. |
277 |
|
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*/ |
278 |
|
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final void internalWait(long timeout) { |
279 |
dl |
1.118 |
if ((int)STATUS.getAndBitwiseOr(this, SIGNAL) >= 0) { |
280 |
dl |
1.87 |
synchronized (this) { |
281 |
|
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if (status >= 0) |
282 |
|
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try { wait(timeout); } catch (InterruptedException ie) { } |
283 |
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else |
284 |
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notifyAll(); |
285 |
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} |
286 |
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} |
287 |
dl |
1.59 |
} |
288 |
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|
289 |
|
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/** |
290 |
dl |
1.40 |
* Blocks a non-worker-thread until completion. |
291 |
dl |
1.45 |
* @return status upon completion |
292 |
dl |
1.19 |
*/ |
293 |
dl |
1.45 |
private int externalAwaitDone() { |
294 |
dl |
1.118 |
int s = tryExternalHelp(); |
295 |
|
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if (s >= 0 && (s = (int)STATUS.getAndBitwiseOr(this, SIGNAL)) >= 0) { |
296 |
dl |
1.87 |
boolean interrupted = false; |
297 |
dl |
1.118 |
synchronized (this) { |
298 |
|
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for (;;) { |
299 |
|
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if ((s = status) >= 0) { |
300 |
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try { |
301 |
|
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wait(0L); |
302 |
|
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} catch (InterruptedException ie) { |
303 |
|
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interrupted = true; |
304 |
dl |
1.43 |
} |
305 |
dl |
1.118 |
} |
306 |
|
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else { |
307 |
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notifyAll(); |
308 |
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break; |
309 |
dl |
1.40 |
} |
310 |
dl |
1.87 |
} |
311 |
dl |
1.118 |
} |
312 |
dl |
1.87 |
if (interrupted) |
313 |
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Thread.currentThread().interrupt(); |
314 |
dl |
1.19 |
} |
315 |
dl |
1.45 |
return s; |
316 |
dl |
1.19 |
} |
317 |
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|
318 |
|
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/** |
319 |
dl |
1.59 |
* Blocks a non-worker-thread until completion or interruption. |
320 |
jsr166 |
1.1 |
*/ |
321 |
dl |
1.59 |
private int externalInterruptibleAwaitDone() throws InterruptedException { |
322 |
dl |
1.118 |
int s = tryExternalHelp(); |
323 |
|
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if (s >= 0 && (s = (int)STATUS.getAndBitwiseOr(this, SIGNAL)) >= 0) { |
324 |
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synchronized (this) { |
325 |
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for (;;) { |
326 |
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if ((s = status) >= 0) |
327 |
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wait(0L); |
328 |
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else { |
329 |
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notifyAll(); |
330 |
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break; |
331 |
dl |
1.87 |
} |
332 |
dl |
1.45 |
} |
333 |
|
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} |
334 |
|
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} |
335 |
dl |
1.118 |
else if (Thread.interrupted()) |
336 |
|
|
throw new InterruptedException(); |
337 |
dl |
1.45 |
return s; |
338 |
|
|
} |
339 |
|
|
|
340 |
|
|
/** |
341 |
dl |
1.118 |
* Tries to help with tasks allowed for external callers. |
342 |
|
|
* |
343 |
|
|
* @return current status |
344 |
|
|
*/ |
345 |
|
|
private int tryExternalHelp() { |
346 |
|
|
int s; |
347 |
|
|
return ((s = status) < 0 ? s: |
348 |
|
|
(this instanceof CountedCompleter) ? |
349 |
|
|
ForkJoinPool.common.externalHelpComplete( |
350 |
|
|
(CountedCompleter<?>)this, 0) : |
351 |
|
|
ForkJoinPool.common.tryExternalUnpush(this) ? |
352 |
|
|
doExec() : 0); |
353 |
|
|
} |
354 |
|
|
|
355 |
|
|
/** |
356 |
dl |
1.54 |
* Implementation for join, get, quietlyJoin. Directly handles |
357 |
|
|
* only cases of already-completed, external wait, and |
358 |
dl |
1.59 |
* unfork+exec. Others are relayed to ForkJoinPool.awaitJoin. |
359 |
dl |
1.54 |
* |
360 |
|
|
* @return status upon completion |
361 |
dl |
1.45 |
*/ |
362 |
dl |
1.54 |
private int doJoin() { |
363 |
|
|
int s; Thread t; ForkJoinWorkerThread wt; ForkJoinPool.WorkQueue w; |
364 |
dl |
1.64 |
return (s = status) < 0 ? s : |
365 |
|
|
((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
366 |
|
|
(w = (wt = (ForkJoinWorkerThread)t).workQueue). |
367 |
|
|
tryUnpush(this) && (s = doExec()) < 0 ? s : |
368 |
dl |
1.87 |
wt.pool.awaitJoin(w, this, 0L) : |
369 |
dl |
1.64 |
externalAwaitDone(); |
370 |
jsr166 |
1.1 |
} |
371 |
|
|
|
372 |
|
|
/** |
373 |
dl |
1.54 |
* Implementation for invoke, quietlyInvoke. |
374 |
|
|
* |
375 |
dl |
1.45 |
* @return status upon completion |
376 |
jsr166 |
1.1 |
*/ |
377 |
dl |
1.45 |
private int doInvoke() { |
378 |
dl |
1.59 |
int s; Thread t; ForkJoinWorkerThread wt; |
379 |
dl |
1.64 |
return (s = doExec()) < 0 ? s : |
380 |
|
|
((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
381 |
dl |
1.87 |
(wt = (ForkJoinWorkerThread)t).pool. |
382 |
|
|
awaitJoin(wt.workQueue, this, 0L) : |
383 |
dl |
1.64 |
externalAwaitDone(); |
384 |
dl |
1.45 |
} |
385 |
|
|
|
386 |
|
|
// Exception table support |
387 |
|
|
|
388 |
|
|
/** |
389 |
jsr166 |
1.113 |
* Hash table of exceptions thrown by tasks, to enable reporting |
390 |
|
|
* by callers. Because exceptions are rare, we don't directly keep |
391 |
dl |
1.45 |
* them with task objects, but instead use a weak ref table. Note |
392 |
|
|
* that cancellation exceptions don't appear in the table, but are |
393 |
|
|
* instead recorded as status values. |
394 |
|
|
* |
395 |
jsr166 |
1.113 |
* The exception table has a fixed capacity. |
396 |
dl |
1.45 |
*/ |
397 |
jsr166 |
1.113 |
private static final ExceptionNode[] exceptionTable |
398 |
|
|
= new ExceptionNode[32]; |
399 |
dl |
1.45 |
|
400 |
jsr166 |
1.113 |
/** Lock protecting access to exceptionTable. */ |
401 |
|
|
private static final ReentrantLock exceptionTableLock |
402 |
|
|
= new ReentrantLock(); |
403 |
|
|
|
404 |
|
|
/** Reference queue of stale exceptionally completed tasks. */ |
405 |
|
|
private static final ReferenceQueue<ForkJoinTask<?>> exceptionTableRefQueue |
406 |
jsr166 |
1.114 |
= new ReferenceQueue<>(); |
407 |
dl |
1.45 |
|
408 |
|
|
/** |
409 |
|
|
* Key-value nodes for exception table. The chained hash table |
410 |
|
|
* uses identity comparisons, full locking, and weak references |
411 |
|
|
* for keys. The table has a fixed capacity because it only |
412 |
|
|
* maintains task exceptions long enough for joiners to access |
413 |
|
|
* them, so should never become very large for sustained |
414 |
|
|
* periods. However, since we do not know when the last joiner |
415 |
|
|
* completes, we must use weak references and expunge them. We do |
416 |
|
|
* so on each operation (hence full locking). Also, some thread in |
417 |
dl |
1.47 |
* any ForkJoinPool will call helpExpungeStaleExceptions when its |
418 |
|
|
* pool becomes isQuiescent. |
419 |
dl |
1.45 |
*/ |
420 |
jsr166 |
1.58 |
static final class ExceptionNode extends WeakReference<ForkJoinTask<?>> { |
421 |
dl |
1.45 |
final Throwable ex; |
422 |
|
|
ExceptionNode next; |
423 |
dl |
1.47 |
final long thrower; // use id not ref to avoid weak cycles |
424 |
dl |
1.85 |
final int hashCode; // store task hashCode before weak ref disappears |
425 |
jsr166 |
1.98 |
ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next, |
426 |
jsr166 |
1.112 |
ReferenceQueue<ForkJoinTask<?>> exceptionTableRefQueue) { |
427 |
dl |
1.45 |
super(task, exceptionTableRefQueue); |
428 |
|
|
this.ex = ex; |
429 |
|
|
this.next = next; |
430 |
|
|
this.thrower = Thread.currentThread().getId(); |
431 |
dl |
1.85 |
this.hashCode = System.identityHashCode(task); |
432 |
dl |
1.45 |
} |
433 |
|
|
} |
434 |
|
|
|
435 |
|
|
/** |
436 |
dl |
1.63 |
* Records exception and sets status. |
437 |
dl |
1.45 |
* |
438 |
|
|
* @return status on exit |
439 |
|
|
*/ |
440 |
dl |
1.63 |
final int recordExceptionalCompletion(Throwable ex) { |
441 |
dl |
1.62 |
int s; |
442 |
|
|
if ((s = status) >= 0) { |
443 |
|
|
int h = System.identityHashCode(this); |
444 |
|
|
final ReentrantLock lock = exceptionTableLock; |
445 |
|
|
lock.lock(); |
446 |
|
|
try { |
447 |
|
|
expungeStaleExceptions(); |
448 |
|
|
ExceptionNode[] t = exceptionTable; |
449 |
|
|
int i = h & (t.length - 1); |
450 |
|
|
for (ExceptionNode e = t[i]; ; e = e.next) { |
451 |
|
|
if (e == null) { |
452 |
jsr166 |
1.98 |
t[i] = new ExceptionNode(this, ex, t[i], |
453 |
|
|
exceptionTableRefQueue); |
454 |
dl |
1.62 |
break; |
455 |
|
|
} |
456 |
|
|
if (e.get() == this) // already present |
457 |
|
|
break; |
458 |
dl |
1.45 |
} |
459 |
dl |
1.62 |
} finally { |
460 |
|
|
lock.unlock(); |
461 |
dl |
1.45 |
} |
462 |
dl |
1.118 |
s = abnormalCompletion(DONE | ABNORMAL | THROWN); |
463 |
dl |
1.45 |
} |
464 |
dl |
1.62 |
return s; |
465 |
|
|
} |
466 |
|
|
|
467 |
|
|
/** |
468 |
jsr166 |
1.70 |
* Records exception and possibly propagates. |
469 |
dl |
1.63 |
* |
470 |
|
|
* @return status on exit |
471 |
|
|
*/ |
472 |
|
|
private int setExceptionalCompletion(Throwable ex) { |
473 |
|
|
int s = recordExceptionalCompletion(ex); |
474 |
dl |
1.118 |
if ((s & THROWN) != 0) |
475 |
dl |
1.63 |
internalPropagateException(ex); |
476 |
|
|
return s; |
477 |
|
|
} |
478 |
|
|
|
479 |
|
|
/** |
480 |
|
|
* Hook for exception propagation support for tasks with completers. |
481 |
dl |
1.62 |
*/ |
482 |
dl |
1.63 |
void internalPropagateException(Throwable ex) { |
483 |
dl |
1.45 |
} |
484 |
|
|
|
485 |
|
|
/** |
486 |
dl |
1.54 |
* Cancels, ignoring any exceptions thrown by cancel. Used during |
487 |
|
|
* worker and pool shutdown. Cancel is spec'ed not to throw any |
488 |
|
|
* exceptions, but if it does anyway, we have no recourse during |
489 |
|
|
* shutdown, so guard against this case. |
490 |
|
|
*/ |
491 |
|
|
static final void cancelIgnoringExceptions(ForkJoinTask<?> t) { |
492 |
|
|
if (t != null && t.status >= 0) { |
493 |
|
|
try { |
494 |
|
|
t.cancel(false); |
495 |
|
|
} catch (Throwable ignore) { |
496 |
|
|
} |
497 |
|
|
} |
498 |
|
|
} |
499 |
|
|
|
500 |
|
|
/** |
501 |
jsr166 |
1.72 |
* Removes exception node and clears status. |
502 |
dl |
1.45 |
*/ |
503 |
|
|
private void clearExceptionalCompletion() { |
504 |
|
|
int h = System.identityHashCode(this); |
505 |
dl |
1.47 |
final ReentrantLock lock = exceptionTableLock; |
506 |
dl |
1.45 |
lock.lock(); |
507 |
|
|
try { |
508 |
|
|
ExceptionNode[] t = exceptionTable; |
509 |
|
|
int i = h & (t.length - 1); |
510 |
|
|
ExceptionNode e = t[i]; |
511 |
|
|
ExceptionNode pred = null; |
512 |
|
|
while (e != null) { |
513 |
|
|
ExceptionNode next = e.next; |
514 |
|
|
if (e.get() == this) { |
515 |
|
|
if (pred == null) |
516 |
|
|
t[i] = next; |
517 |
|
|
else |
518 |
|
|
pred.next = next; |
519 |
|
|
break; |
520 |
|
|
} |
521 |
|
|
pred = e; |
522 |
|
|
e = next; |
523 |
|
|
} |
524 |
|
|
expungeStaleExceptions(); |
525 |
|
|
status = 0; |
526 |
|
|
} finally { |
527 |
|
|
lock.unlock(); |
528 |
|
|
} |
529 |
|
|
} |
530 |
|
|
|
531 |
|
|
/** |
532 |
jsr166 |
1.105 |
* Returns a rethrowable exception for this task, if available. |
533 |
|
|
* To provide accurate stack traces, if the exception was not |
534 |
|
|
* thrown by the current thread, we try to create a new exception |
535 |
|
|
* of the same type as the one thrown, but with the recorded |
536 |
|
|
* exception as its cause. If there is no such constructor, we |
537 |
|
|
* instead try to use a no-arg constructor, followed by initCause, |
538 |
|
|
* to the same effect. If none of these apply, or any fail due to |
539 |
|
|
* other exceptions, we return the recorded exception, which is |
540 |
|
|
* still correct, although it may contain a misleading stack |
541 |
|
|
* trace. |
542 |
dl |
1.45 |
* |
543 |
|
|
* @return the exception, or null if none |
544 |
|
|
*/ |
545 |
|
|
private Throwable getThrowableException() { |
546 |
|
|
int h = System.identityHashCode(this); |
547 |
|
|
ExceptionNode e; |
548 |
dl |
1.47 |
final ReentrantLock lock = exceptionTableLock; |
549 |
dl |
1.45 |
lock.lock(); |
550 |
|
|
try { |
551 |
|
|
expungeStaleExceptions(); |
552 |
|
|
ExceptionNode[] t = exceptionTable; |
553 |
|
|
e = t[h & (t.length - 1)]; |
554 |
|
|
while (e != null && e.get() != this) |
555 |
|
|
e = e.next; |
556 |
|
|
} finally { |
557 |
|
|
lock.unlock(); |
558 |
|
|
} |
559 |
|
|
Throwable ex; |
560 |
|
|
if (e == null || (ex = e.ex) == null) |
561 |
|
|
return null; |
562 |
dl |
1.86 |
if (e.thrower != Thread.currentThread().getId()) { |
563 |
dl |
1.45 |
try { |
564 |
|
|
Constructor<?> noArgCtor = null; |
565 |
jsr166 |
1.106 |
// public ctors only |
566 |
|
|
for (Constructor<?> c : ex.getClass().getConstructors()) { |
567 |
dl |
1.45 |
Class<?>[] ps = c.getParameterTypes(); |
568 |
|
|
if (ps.length == 0) |
569 |
|
|
noArgCtor = c; |
570 |
jsr166 |
1.106 |
else if (ps.length == 1 && ps[0] == Throwable.class) |
571 |
|
|
return (Throwable)c.newInstance(ex); |
572 |
dl |
1.45 |
} |
573 |
|
|
if (noArgCtor != null) { |
574 |
jsr166 |
1.106 |
Throwable wx = (Throwable)noArgCtor.newInstance(); |
575 |
|
|
wx.initCause(ex); |
576 |
|
|
return wx; |
577 |
dl |
1.45 |
} |
578 |
|
|
} catch (Exception ignore) { |
579 |
|
|
} |
580 |
|
|
} |
581 |
|
|
return ex; |
582 |
|
|
} |
583 |
|
|
|
584 |
|
|
/** |
585 |
jsr166 |
1.101 |
* Polls stale refs and removes them. Call only while holding lock. |
586 |
dl |
1.45 |
*/ |
587 |
|
|
private static void expungeStaleExceptions() { |
588 |
|
|
for (Object x; (x = exceptionTableRefQueue.poll()) != null;) { |
589 |
|
|
if (x instanceof ExceptionNode) { |
590 |
|
|
ExceptionNode[] t = exceptionTable; |
591 |
jsr166 |
1.111 |
int i = ((ExceptionNode)x).hashCode & (t.length - 1); |
592 |
dl |
1.45 |
ExceptionNode e = t[i]; |
593 |
|
|
ExceptionNode pred = null; |
594 |
|
|
while (e != null) { |
595 |
|
|
ExceptionNode next = e.next; |
596 |
|
|
if (e == x) { |
597 |
|
|
if (pred == null) |
598 |
|
|
t[i] = next; |
599 |
|
|
else |
600 |
|
|
pred.next = next; |
601 |
|
|
break; |
602 |
|
|
} |
603 |
|
|
pred = e; |
604 |
|
|
e = next; |
605 |
|
|
} |
606 |
|
|
} |
607 |
|
|
} |
608 |
|
|
} |
609 |
|
|
|
610 |
|
|
/** |
611 |
jsr166 |
1.101 |
* If lock is available, polls stale refs and removes them. |
612 |
dl |
1.45 |
* Called from ForkJoinPool when pools become quiescent. |
613 |
|
|
*/ |
614 |
|
|
static final void helpExpungeStaleExceptions() { |
615 |
dl |
1.47 |
final ReentrantLock lock = exceptionTableLock; |
616 |
dl |
1.45 |
if (lock.tryLock()) { |
617 |
|
|
try { |
618 |
|
|
expungeStaleExceptions(); |
619 |
|
|
} finally { |
620 |
|
|
lock.unlock(); |
621 |
|
|
} |
622 |
jsr166 |
1.1 |
} |
623 |
dl |
1.45 |
} |
624 |
|
|
|
625 |
|
|
/** |
626 |
jsr166 |
1.99 |
* A version of "sneaky throw" to relay exceptions. |
627 |
dl |
1.65 |
*/ |
628 |
jsr166 |
1.78 |
static void rethrow(Throwable ex) { |
629 |
dl |
1.100 |
ForkJoinTask.<RuntimeException>uncheckedThrow(ex); |
630 |
dl |
1.65 |
} |
631 |
|
|
|
632 |
|
|
/** |
633 |
|
|
* The sneaky part of sneaky throw, relying on generics |
634 |
|
|
* limitations to evade compiler complaints about rethrowing |
635 |
jsr166 |
1.99 |
* unchecked exceptions. |
636 |
dl |
1.65 |
*/ |
637 |
|
|
@SuppressWarnings("unchecked") static <T extends Throwable> |
638 |
dl |
1.100 |
void uncheckedThrow(Throwable t) throws T { |
639 |
|
|
if (t != null) |
640 |
|
|
throw (T)t; // rely on vacuous cast |
641 |
|
|
else |
642 |
|
|
throw new Error("Unknown Exception"); |
643 |
dl |
1.65 |
} |
644 |
|
|
|
645 |
|
|
/** |
646 |
dl |
1.59 |
* Throws exception, if any, associated with the given status. |
647 |
dl |
1.45 |
*/ |
648 |
dl |
1.59 |
private void reportException(int s) { |
649 |
dl |
1.118 |
rethrow((s & THROWN) != 0 ? getThrowableException() : |
650 |
|
|
new CancellationException()); |
651 |
jsr166 |
1.1 |
} |
652 |
|
|
|
653 |
|
|
// public methods |
654 |
|
|
|
655 |
|
|
/** |
656 |
dl |
1.64 |
* Arranges to asynchronously execute this task in the pool the |
657 |
|
|
* current task is running in, if applicable, or using the {@link |
658 |
dl |
1.67 |
* ForkJoinPool#commonPool()} if not {@link #inForkJoinPool}. While |
659 |
dl |
1.64 |
* it is not necessarily enforced, it is a usage error to fork a |
660 |
|
|
* task more than once unless it has completed and been |
661 |
|
|
* reinitialized. Subsequent modifications to the state of this |
662 |
|
|
* task or any data it operates on are not necessarily |
663 |
|
|
* consistently observable by any thread other than the one |
664 |
|
|
* executing it unless preceded by a call to {@link #join} or |
665 |
|
|
* related methods, or a call to {@link #isDone} returning {@code |
666 |
|
|
* true}. |
667 |
jsr166 |
1.2 |
* |
668 |
jsr166 |
1.6 |
* @return {@code this}, to simplify usage |
669 |
jsr166 |
1.1 |
*/ |
670 |
jsr166 |
1.2 |
public final ForkJoinTask<V> fork() { |
671 |
dl |
1.64 |
Thread t; |
672 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
673 |
|
|
((ForkJoinWorkerThread)t).workQueue.push(this); |
674 |
|
|
else |
675 |
dl |
1.71 |
ForkJoinPool.common.externalPush(this); |
676 |
jsr166 |
1.2 |
return this; |
677 |
jsr166 |
1.1 |
} |
678 |
|
|
|
679 |
|
|
/** |
680 |
jsr166 |
1.115 |
* Returns the result of the computation when it |
681 |
|
|
* {@linkplain #isDone is done}. |
682 |
|
|
* This method differs from {@link #get()} in that abnormal |
683 |
|
|
* completion results in {@code RuntimeException} or {@code Error}, |
684 |
|
|
* not {@code ExecutionException}, and that interrupts of the |
685 |
|
|
* calling thread do <em>not</em> cause the method to abruptly |
686 |
|
|
* return by throwing {@code InterruptedException}. |
687 |
jsr166 |
1.1 |
* |
688 |
|
|
* @return the computed result |
689 |
|
|
*/ |
690 |
|
|
public final V join() { |
691 |
dl |
1.59 |
int s; |
692 |
dl |
1.118 |
if (((s = doJoin()) & ABNORMAL) != 0) |
693 |
dl |
1.59 |
reportException(s); |
694 |
|
|
return getRawResult(); |
695 |
jsr166 |
1.1 |
} |
696 |
|
|
|
697 |
|
|
/** |
698 |
|
|
* Commences performing this task, awaits its completion if |
699 |
jsr166 |
1.21 |
* necessary, and returns its result, or throws an (unchecked) |
700 |
dl |
1.20 |
* {@code RuntimeException} or {@code Error} if the underlying |
701 |
|
|
* computation did so. |
702 |
jsr166 |
1.1 |
* |
703 |
|
|
* @return the computed result |
704 |
|
|
*/ |
705 |
|
|
public final V invoke() { |
706 |
dl |
1.59 |
int s; |
707 |
dl |
1.118 |
if (((s = doInvoke()) & ABNORMAL) != 0) |
708 |
dl |
1.59 |
reportException(s); |
709 |
|
|
return getRawResult(); |
710 |
jsr166 |
1.1 |
} |
711 |
|
|
|
712 |
|
|
/** |
713 |
jsr166 |
1.8 |
* Forks the given tasks, returning when {@code isDone} holds for |
714 |
|
|
* each task or an (unchecked) exception is encountered, in which |
715 |
dl |
1.20 |
* case the exception is rethrown. If more than one task |
716 |
|
|
* encounters an exception, then this method throws any one of |
717 |
|
|
* these exceptions. If any task encounters an exception, the |
718 |
|
|
* other may be cancelled. However, the execution status of |
719 |
|
|
* individual tasks is not guaranteed upon exceptional return. The |
720 |
|
|
* status of each task may be obtained using {@link |
721 |
|
|
* #getException()} and related methods to check if they have been |
722 |
|
|
* cancelled, completed normally or exceptionally, or left |
723 |
|
|
* unprocessed. |
724 |
jsr166 |
1.6 |
* |
725 |
|
|
* @param t1 the first task |
726 |
|
|
* @param t2 the second task |
727 |
|
|
* @throws NullPointerException if any task is null |
728 |
jsr166 |
1.1 |
*/ |
729 |
jsr166 |
1.6 |
public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) { |
730 |
dl |
1.59 |
int s1, s2; |
731 |
jsr166 |
1.1 |
t2.fork(); |
732 |
dl |
1.118 |
if (((s1 = t1.doInvoke()) & ABNORMAL) != 0) |
733 |
dl |
1.59 |
t1.reportException(s1); |
734 |
dl |
1.118 |
if (((s2 = t2.doJoin()) & ABNORMAL) != 0) |
735 |
dl |
1.59 |
t2.reportException(s2); |
736 |
jsr166 |
1.1 |
} |
737 |
|
|
|
738 |
|
|
/** |
739 |
jsr166 |
1.6 |
* Forks the given tasks, returning when {@code isDone} holds for |
740 |
jsr166 |
1.8 |
* each task or an (unchecked) exception is encountered, in which |
741 |
dl |
1.20 |
* case the exception is rethrown. If more than one task |
742 |
|
|
* encounters an exception, then this method throws any one of |
743 |
|
|
* these exceptions. If any task encounters an exception, others |
744 |
|
|
* may be cancelled. However, the execution status of individual |
745 |
|
|
* tasks is not guaranteed upon exceptional return. The status of |
746 |
|
|
* each task may be obtained using {@link #getException()} and |
747 |
|
|
* related methods to check if they have been cancelled, completed |
748 |
|
|
* normally or exceptionally, or left unprocessed. |
749 |
jsr166 |
1.6 |
* |
750 |
|
|
* @param tasks the tasks |
751 |
jsr166 |
1.8 |
* @throws NullPointerException if any task is null |
752 |
jsr166 |
1.1 |
*/ |
753 |
|
|
public static void invokeAll(ForkJoinTask<?>... tasks) { |
754 |
|
|
Throwable ex = null; |
755 |
|
|
int last = tasks.length - 1; |
756 |
|
|
for (int i = last; i >= 0; --i) { |
757 |
|
|
ForkJoinTask<?> t = tasks[i]; |
758 |
|
|
if (t == null) { |
759 |
|
|
if (ex == null) |
760 |
|
|
ex = new NullPointerException(); |
761 |
|
|
} |
762 |
|
|
else if (i != 0) |
763 |
|
|
t.fork(); |
764 |
dl |
1.118 |
else if ((t.doInvoke() & ABNORMAL) != 0 && ex == null) |
765 |
dl |
1.45 |
ex = t.getException(); |
766 |
jsr166 |
1.1 |
} |
767 |
|
|
for (int i = 1; i <= last; ++i) { |
768 |
|
|
ForkJoinTask<?> t = tasks[i]; |
769 |
|
|
if (t != null) { |
770 |
|
|
if (ex != null) |
771 |
|
|
t.cancel(false); |
772 |
dl |
1.118 |
else if ((t.doJoin() & ABNORMAL) != 0) |
773 |
dl |
1.45 |
ex = t.getException(); |
774 |
jsr166 |
1.1 |
} |
775 |
|
|
} |
776 |
|
|
if (ex != null) |
777 |
dl |
1.65 |
rethrow(ex); |
778 |
jsr166 |
1.1 |
} |
779 |
|
|
|
780 |
|
|
/** |
781 |
jsr166 |
1.7 |
* Forks all tasks in the specified collection, returning when |
782 |
jsr166 |
1.8 |
* {@code isDone} holds for each task or an (unchecked) exception |
783 |
dl |
1.20 |
* is encountered, in which case the exception is rethrown. If |
784 |
|
|
* more than one task encounters an exception, then this method |
785 |
|
|
* throws any one of these exceptions. If any task encounters an |
786 |
|
|
* exception, others may be cancelled. However, the execution |
787 |
|
|
* status of individual tasks is not guaranteed upon exceptional |
788 |
|
|
* return. The status of each task may be obtained using {@link |
789 |
|
|
* #getException()} and related methods to check if they have been |
790 |
|
|
* cancelled, completed normally or exceptionally, or left |
791 |
|
|
* unprocessed. |
792 |
jsr166 |
1.6 |
* |
793 |
jsr166 |
1.1 |
* @param tasks the collection of tasks |
794 |
jsr166 |
1.82 |
* @param <T> the type of the values returned from the tasks |
795 |
jsr166 |
1.2 |
* @return the tasks argument, to simplify usage |
796 |
jsr166 |
1.1 |
* @throws NullPointerException if tasks or any element are null |
797 |
|
|
*/ |
798 |
jsr166 |
1.2 |
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
799 |
jsr166 |
1.7 |
if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) { |
800 |
jsr166 |
1.121 |
invokeAll(tasks.toArray(new ForkJoinTask<?>[0])); |
801 |
jsr166 |
1.2 |
return tasks; |
802 |
jsr166 |
1.1 |
} |
803 |
|
|
@SuppressWarnings("unchecked") |
804 |
|
|
List<? extends ForkJoinTask<?>> ts = |
805 |
|
|
(List<? extends ForkJoinTask<?>>) tasks; |
806 |
|
|
Throwable ex = null; |
807 |
|
|
int last = ts.size() - 1; |
808 |
|
|
for (int i = last; i >= 0; --i) { |
809 |
|
|
ForkJoinTask<?> t = ts.get(i); |
810 |
|
|
if (t == null) { |
811 |
|
|
if (ex == null) |
812 |
|
|
ex = new NullPointerException(); |
813 |
|
|
} |
814 |
|
|
else if (i != 0) |
815 |
|
|
t.fork(); |
816 |
dl |
1.118 |
else if ((t.doInvoke() & ABNORMAL) != 0 && ex == null) |
817 |
dl |
1.45 |
ex = t.getException(); |
818 |
jsr166 |
1.1 |
} |
819 |
|
|
for (int i = 1; i <= last; ++i) { |
820 |
|
|
ForkJoinTask<?> t = ts.get(i); |
821 |
|
|
if (t != null) { |
822 |
|
|
if (ex != null) |
823 |
|
|
t.cancel(false); |
824 |
dl |
1.118 |
else if ((t.doJoin() & ABNORMAL) != 0) |
825 |
dl |
1.45 |
ex = t.getException(); |
826 |
jsr166 |
1.1 |
} |
827 |
|
|
} |
828 |
|
|
if (ex != null) |
829 |
dl |
1.65 |
rethrow(ex); |
830 |
jsr166 |
1.2 |
return tasks; |
831 |
jsr166 |
1.1 |
} |
832 |
|
|
|
833 |
|
|
/** |
834 |
jsr166 |
1.7 |
* Attempts to cancel execution of this task. This attempt will |
835 |
jsr166 |
1.36 |
* fail if the task has already completed or could not be |
836 |
|
|
* cancelled for some other reason. If successful, and this task |
837 |
|
|
* has not started when {@code cancel} is called, execution of |
838 |
dl |
1.38 |
* this task is suppressed. After this method returns |
839 |
|
|
* successfully, unless there is an intervening call to {@link |
840 |
|
|
* #reinitialize}, subsequent calls to {@link #isCancelled}, |
841 |
|
|
* {@link #isDone}, and {@code cancel} will return {@code true} |
842 |
|
|
* and calls to {@link #join} and related methods will result in |
843 |
|
|
* {@code CancellationException}. |
844 |
jsr166 |
1.1 |
* |
845 |
|
|
* <p>This method may be overridden in subclasses, but if so, must |
846 |
dl |
1.38 |
* still ensure that these properties hold. In particular, the |
847 |
|
|
* {@code cancel} method itself must not throw exceptions. |
848 |
jsr166 |
1.1 |
* |
849 |
jsr166 |
1.6 |
* <p>This method is designed to be invoked by <em>other</em> |
850 |
jsr166 |
1.1 |
* tasks. To terminate the current task, you can just return or |
851 |
|
|
* throw an unchecked exception from its computation method, or |
852 |
jsr166 |
1.74 |
* invoke {@link #completeExceptionally(Throwable)}. |
853 |
jsr166 |
1.1 |
* |
854 |
dl |
1.38 |
* @param mayInterruptIfRunning this value has no effect in the |
855 |
|
|
* default implementation because interrupts are not used to |
856 |
|
|
* control cancellation. |
857 |
jsr166 |
1.1 |
* |
858 |
jsr166 |
1.4 |
* @return {@code true} if this task is now cancelled |
859 |
jsr166 |
1.1 |
*/ |
860 |
|
|
public boolean cancel(boolean mayInterruptIfRunning) { |
861 |
dl |
1.118 |
int s = abnormalCompletion(DONE | ABNORMAL); |
862 |
|
|
return (s & (ABNORMAL | THROWN)) == ABNORMAL; |
863 |
jsr166 |
1.1 |
} |
864 |
|
|
|
865 |
jsr166 |
1.8 |
public final boolean isDone() { |
866 |
|
|
return status < 0; |
867 |
|
|
} |
868 |
|
|
|
869 |
|
|
public final boolean isCancelled() { |
870 |
dl |
1.118 |
return (status & (ABNORMAL | THROWN)) == ABNORMAL; |
871 |
jsr166 |
1.8 |
} |
872 |
|
|
|
873 |
|
|
/** |
874 |
jsr166 |
1.4 |
* Returns {@code true} if this task threw an exception or was cancelled. |
875 |
jsr166 |
1.1 |
* |
876 |
jsr166 |
1.4 |
* @return {@code true} if this task threw an exception or was cancelled |
877 |
jsr166 |
1.1 |
*/ |
878 |
|
|
public final boolean isCompletedAbnormally() { |
879 |
dl |
1.118 |
return (status & ABNORMAL) != 0; |
880 |
jsr166 |
1.1 |
} |
881 |
|
|
|
882 |
|
|
/** |
883 |
jsr166 |
1.8 |
* Returns {@code true} if this task completed without throwing an |
884 |
|
|
* exception and was not cancelled. |
885 |
|
|
* |
886 |
|
|
* @return {@code true} if this task completed without throwing an |
887 |
|
|
* exception and was not cancelled |
888 |
|
|
*/ |
889 |
|
|
public final boolean isCompletedNormally() { |
890 |
dl |
1.118 |
return (status & (DONE | ABNORMAL)) == DONE; |
891 |
jsr166 |
1.8 |
} |
892 |
|
|
|
893 |
|
|
/** |
894 |
jsr166 |
1.1 |
* Returns the exception thrown by the base computation, or a |
895 |
jsr166 |
1.6 |
* {@code CancellationException} if cancelled, or {@code null} if |
896 |
|
|
* none or if the method has not yet completed. |
897 |
jsr166 |
1.1 |
* |
898 |
jsr166 |
1.4 |
* @return the exception, or {@code null} if none |
899 |
jsr166 |
1.1 |
*/ |
900 |
|
|
public final Throwable getException() { |
901 |
dl |
1.118 |
int s = status; |
902 |
|
|
return ((s & ABNORMAL) == 0 ? null : |
903 |
|
|
(s & THROWN) == 0 ? new CancellationException() : |
904 |
dl |
1.45 |
getThrowableException()); |
905 |
jsr166 |
1.1 |
} |
906 |
|
|
|
907 |
|
|
/** |
908 |
|
|
* Completes this task abnormally, and if not already aborted or |
909 |
|
|
* cancelled, causes it to throw the given exception upon |
910 |
|
|
* {@code join} and related operations. This method may be used |
911 |
|
|
* to induce exceptions in asynchronous tasks, or to force |
912 |
|
|
* completion of tasks that would not otherwise complete. Its use |
913 |
jsr166 |
1.6 |
* in other situations is discouraged. This method is |
914 |
jsr166 |
1.1 |
* overridable, but overridden versions must invoke {@code super} |
915 |
|
|
* implementation to maintain guarantees. |
916 |
|
|
* |
917 |
jsr166 |
1.11 |
* @param ex the exception to throw. If this exception is not a |
918 |
|
|
* {@code RuntimeException} or {@code Error}, the actual exception |
919 |
|
|
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
920 |
jsr166 |
1.1 |
*/ |
921 |
|
|
public void completeExceptionally(Throwable ex) { |
922 |
dl |
1.15 |
setExceptionalCompletion((ex instanceof RuntimeException) || |
923 |
|
|
(ex instanceof Error) ? ex : |
924 |
|
|
new RuntimeException(ex)); |
925 |
jsr166 |
1.1 |
} |
926 |
|
|
|
927 |
|
|
/** |
928 |
|
|
* Completes this task, and if not already aborted or cancelled, |
929 |
dl |
1.22 |
* returning the given value as the result of subsequent |
930 |
|
|
* invocations of {@code join} and related operations. This method |
931 |
|
|
* may be used to provide results for asynchronous tasks, or to |
932 |
|
|
* provide alternative handling for tasks that would not otherwise |
933 |
|
|
* complete normally. Its use in other situations is |
934 |
|
|
* discouraged. This method is overridable, but overridden |
935 |
|
|
* versions must invoke {@code super} implementation to maintain |
936 |
|
|
* guarantees. |
937 |
jsr166 |
1.1 |
* |
938 |
|
|
* @param value the result value for this task |
939 |
|
|
*/ |
940 |
|
|
public void complete(V value) { |
941 |
|
|
try { |
942 |
|
|
setRawResult(value); |
943 |
|
|
} catch (Throwable rex) { |
944 |
dl |
1.15 |
setExceptionalCompletion(rex); |
945 |
jsr166 |
1.1 |
return; |
946 |
|
|
} |
947 |
dl |
1.118 |
setDone(); |
948 |
jsr166 |
1.1 |
} |
949 |
|
|
|
950 |
jsr166 |
1.25 |
/** |
951 |
dl |
1.62 |
* Completes this task normally without setting a value. The most |
952 |
|
|
* recent value established by {@link #setRawResult} (or {@code |
953 |
|
|
* null} by default) will be returned as the result of subsequent |
954 |
|
|
* invocations of {@code join} and related operations. |
955 |
|
|
* |
956 |
|
|
* @since 1.8 |
957 |
dl |
1.60 |
*/ |
958 |
|
|
public final void quietlyComplete() { |
959 |
dl |
1.118 |
setDone(); |
960 |
dl |
1.60 |
} |
961 |
|
|
|
962 |
|
|
/** |
963 |
dl |
1.29 |
* Waits if necessary for the computation to complete, and then |
964 |
|
|
* retrieves its result. |
965 |
|
|
* |
966 |
|
|
* @return the computed result |
967 |
|
|
* @throws CancellationException if the computation was cancelled |
968 |
|
|
* @throws ExecutionException if the computation threw an |
969 |
|
|
* exception |
970 |
|
|
* @throws InterruptedException if the current thread is not a |
971 |
|
|
* member of a ForkJoinPool and was interrupted while waiting |
972 |
jsr166 |
1.25 |
*/ |
973 |
jsr166 |
1.1 |
public final V get() throws InterruptedException, ExecutionException { |
974 |
dl |
1.45 |
int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ? |
975 |
dl |
1.59 |
doJoin() : externalInterruptibleAwaitDone(); |
976 |
dl |
1.118 |
if ((s & THROWN) != 0) |
977 |
|
|
throw new ExecutionException(getThrowableException()); |
978 |
|
|
else if ((s & ABNORMAL) != 0) |
979 |
dl |
1.45 |
throw new CancellationException(); |
980 |
dl |
1.118 |
else |
981 |
|
|
return getRawResult(); |
982 |
jsr166 |
1.1 |
} |
983 |
dl |
1.14 |
|
984 |
jsr166 |
1.25 |
/** |
985 |
dl |
1.29 |
* Waits if necessary for at most the given time for the computation |
986 |
|
|
* to complete, and then retrieves its result, if available. |
987 |
|
|
* |
988 |
|
|
* @param timeout the maximum time to wait |
989 |
|
|
* @param unit the time unit of the timeout argument |
990 |
|
|
* @return the computed result |
991 |
|
|
* @throws CancellationException if the computation was cancelled |
992 |
|
|
* @throws ExecutionException if the computation threw an |
993 |
|
|
* exception |
994 |
|
|
* @throws InterruptedException if the current thread is not a |
995 |
|
|
* member of a ForkJoinPool and was interrupted while waiting |
996 |
|
|
* @throws TimeoutException if the wait timed out |
997 |
jsr166 |
1.25 |
*/ |
998 |
jsr166 |
1.1 |
public final V get(long timeout, TimeUnit unit) |
999 |
|
|
throws InterruptedException, ExecutionException, TimeoutException { |
1000 |
dl |
1.87 |
int s; |
1001 |
|
|
long nanos = unit.toNanos(timeout); |
1002 |
dl |
1.59 |
if (Thread.interrupted()) |
1003 |
|
|
throw new InterruptedException(); |
1004 |
dl |
1.87 |
if ((s = status) >= 0 && nanos > 0L) { |
1005 |
|
|
long d = System.nanoTime() + nanos; |
1006 |
jsr166 |
1.88 |
long deadline = (d == 0L) ? 1L : d; // avoid 0 |
1007 |
dl |
1.59 |
Thread t = Thread.currentThread(); |
1008 |
|
|
if (t instanceof ForkJoinWorkerThread) { |
1009 |
|
|
ForkJoinWorkerThread wt = (ForkJoinWorkerThread)t; |
1010 |
dl |
1.87 |
s = wt.pool.awaitJoin(wt.workQueue, this, deadline); |
1011 |
dl |
1.59 |
} |
1012 |
dl |
1.87 |
else if ((s = ((this instanceof CountedCompleter) ? |
1013 |
|
|
ForkJoinPool.common.externalHelpComplete( |
1014 |
|
|
(CountedCompleter<?>)this, 0) : |
1015 |
|
|
ForkJoinPool.common.tryExternalUnpush(this) ? |
1016 |
|
|
doExec() : 0)) >= 0) { |
1017 |
|
|
long ns, ms; // measure in nanosecs, but wait in millisecs |
1018 |
|
|
while ((s = status) >= 0 && |
1019 |
|
|
(ns = deadline - System.nanoTime()) > 0L) { |
1020 |
|
|
if ((ms = TimeUnit.NANOSECONDS.toMillis(ns)) > 0L && |
1021 |
dl |
1.118 |
(s = (int)STATUS.getAndBitwiseOr(this, SIGNAL)) >= 0) { |
1022 |
dl |
1.87 |
synchronized (this) { |
1023 |
|
|
if (status >= 0) |
1024 |
|
|
wait(ms); // OK to throw InterruptedException |
1025 |
|
|
else |
1026 |
|
|
notifyAll(); |
1027 |
dl |
1.54 |
} |
1028 |
dl |
1.45 |
} |
1029 |
|
|
} |
1030 |
|
|
} |
1031 |
|
|
} |
1032 |
dl |
1.87 |
if (s >= 0) |
1033 |
dl |
1.118 |
throw new TimeoutException(); |
1034 |
|
|
else if ((s & THROWN) != 0) |
1035 |
dl |
1.100 |
throw new ExecutionException(getThrowableException()); |
1036 |
dl |
1.118 |
else if ((s & ABNORMAL) != 0) |
1037 |
|
|
throw new CancellationException(); |
1038 |
|
|
else |
1039 |
|
|
return getRawResult(); |
1040 |
jsr166 |
1.1 |
} |
1041 |
|
|
|
1042 |
|
|
/** |
1043 |
dl |
1.17 |
* Joins this task, without returning its result or throwing its |
1044 |
jsr166 |
1.1 |
* exception. This method may be useful when processing |
1045 |
|
|
* collections of tasks when some have been cancelled or otherwise |
1046 |
|
|
* known to have aborted. |
1047 |
|
|
*/ |
1048 |
|
|
public final void quietlyJoin() { |
1049 |
dl |
1.45 |
doJoin(); |
1050 |
jsr166 |
1.1 |
} |
1051 |
|
|
|
1052 |
|
|
/** |
1053 |
|
|
* Commences performing this task and awaits its completion if |
1054 |
dl |
1.17 |
* necessary, without returning its result or throwing its |
1055 |
dl |
1.22 |
* exception. |
1056 |
jsr166 |
1.1 |
*/ |
1057 |
|
|
public final void quietlyInvoke() { |
1058 |
dl |
1.45 |
doInvoke(); |
1059 |
jsr166 |
1.1 |
} |
1060 |
|
|
|
1061 |
|
|
/** |
1062 |
|
|
* Possibly executes tasks until the pool hosting the current task |
1063 |
jsr166 |
1.104 |
* {@linkplain ForkJoinPool#isQuiescent is quiescent}. This |
1064 |
|
|
* method may be of use in designs in which many tasks are forked, |
1065 |
|
|
* but none are explicitly joined, instead executing them until |
1066 |
|
|
* all are processed. |
1067 |
jsr166 |
1.1 |
*/ |
1068 |
|
|
public static void helpQuiesce() { |
1069 |
dl |
1.64 |
Thread t; |
1070 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) { |
1071 |
|
|
ForkJoinWorkerThread wt = (ForkJoinWorkerThread)t; |
1072 |
|
|
wt.pool.helpQuiescePool(wt.workQueue); |
1073 |
|
|
} |
1074 |
|
|
else |
1075 |
dl |
1.71 |
ForkJoinPool.quiesceCommonPool(); |
1076 |
jsr166 |
1.1 |
} |
1077 |
|
|
|
1078 |
|
|
/** |
1079 |
|
|
* Resets the internal bookkeeping state of this task, allowing a |
1080 |
|
|
* subsequent {@code fork}. This method allows repeated reuse of |
1081 |
|
|
* this task, but only if reuse occurs when this task has either |
1082 |
|
|
* never been forked, or has been forked, then completed and all |
1083 |
|
|
* outstanding joins of this task have also completed. Effects |
1084 |
jsr166 |
1.6 |
* under any other usage conditions are not guaranteed. |
1085 |
|
|
* This method may be useful when executing |
1086 |
jsr166 |
1.1 |
* pre-constructed trees of subtasks in loops. |
1087 |
jsr166 |
1.34 |
* |
1088 |
dl |
1.33 |
* <p>Upon completion of this method, {@code isDone()} reports |
1089 |
|
|
* {@code false}, and {@code getException()} reports {@code |
1090 |
|
|
* null}. However, the value returned by {@code getRawResult} is |
1091 |
|
|
* unaffected. To clear this value, you can invoke {@code |
1092 |
|
|
* setRawResult(null)}. |
1093 |
jsr166 |
1.1 |
*/ |
1094 |
|
|
public void reinitialize() { |
1095 |
dl |
1.118 |
if ((status & THROWN) != 0) |
1096 |
dl |
1.45 |
clearExceptionalCompletion(); |
1097 |
|
|
else |
1098 |
|
|
status = 0; |
1099 |
jsr166 |
1.1 |
} |
1100 |
|
|
|
1101 |
|
|
/** |
1102 |
jsr166 |
1.103 |
* Returns the pool hosting the current thread, or {@code null} |
1103 |
|
|
* if the current thread is executing outside of any ForkJoinPool. |
1104 |
|
|
* |
1105 |
|
|
* <p>This method returns {@code null} if and only if {@link |
1106 |
|
|
* #inForkJoinPool} returns {@code false}. |
1107 |
jsr166 |
1.1 |
* |
1108 |
jsr166 |
1.97 |
* @return the pool, or {@code null} if none |
1109 |
jsr166 |
1.1 |
*/ |
1110 |
|
|
public static ForkJoinPool getPool() { |
1111 |
|
|
Thread t = Thread.currentThread(); |
1112 |
|
|
return (t instanceof ForkJoinWorkerThread) ? |
1113 |
|
|
((ForkJoinWorkerThread) t).pool : null; |
1114 |
|
|
} |
1115 |
|
|
|
1116 |
|
|
/** |
1117 |
dl |
1.42 |
* Returns {@code true} if the current thread is a {@link |
1118 |
|
|
* ForkJoinWorkerThread} executing as a ForkJoinPool computation. |
1119 |
jsr166 |
1.1 |
* |
1120 |
dl |
1.42 |
* @return {@code true} if the current thread is a {@link |
1121 |
|
|
* ForkJoinWorkerThread} executing as a ForkJoinPool computation, |
1122 |
|
|
* or {@code false} otherwise |
1123 |
jsr166 |
1.1 |
*/ |
1124 |
|
|
public static boolean inForkJoinPool() { |
1125 |
|
|
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
1126 |
|
|
} |
1127 |
|
|
|
1128 |
|
|
/** |
1129 |
|
|
* Tries to unschedule this task for execution. This method will |
1130 |
dl |
1.64 |
* typically (but is not guaranteed to) succeed if this task is |
1131 |
|
|
* the most recently forked task by the current thread, and has |
1132 |
|
|
* not commenced executing in another thread. This method may be |
1133 |
|
|
* useful when arranging alternative local processing of tasks |
1134 |
|
|
* that could have been, but were not, stolen. |
1135 |
jsr166 |
1.1 |
* |
1136 |
jsr166 |
1.4 |
* @return {@code true} if unforked |
1137 |
jsr166 |
1.1 |
*/ |
1138 |
|
|
public boolean tryUnfork() { |
1139 |
dl |
1.64 |
Thread t; |
1140 |
dl |
1.66 |
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1141 |
|
|
((ForkJoinWorkerThread)t).workQueue.tryUnpush(this) : |
1142 |
dl |
1.75 |
ForkJoinPool.common.tryExternalUnpush(this)); |
1143 |
jsr166 |
1.1 |
} |
1144 |
|
|
|
1145 |
|
|
/** |
1146 |
|
|
* Returns an estimate of the number of tasks that have been |
1147 |
|
|
* forked by the current worker thread but not yet executed. This |
1148 |
|
|
* value may be useful for heuristic decisions about whether to |
1149 |
|
|
* fork other tasks. |
1150 |
|
|
* |
1151 |
|
|
* @return the number of tasks |
1152 |
|
|
*/ |
1153 |
|
|
public static int getQueuedTaskCount() { |
1154 |
dl |
1.66 |
Thread t; ForkJoinPool.WorkQueue q; |
1155 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
1156 |
|
|
q = ((ForkJoinWorkerThread)t).workQueue; |
1157 |
|
|
else |
1158 |
|
|
q = ForkJoinPool.commonSubmitterQueue(); |
1159 |
|
|
return (q == null) ? 0 : q.queueSize(); |
1160 |
jsr166 |
1.1 |
} |
1161 |
|
|
|
1162 |
|
|
/** |
1163 |
|
|
* Returns an estimate of how many more locally queued tasks are |
1164 |
|
|
* held by the current worker thread than there are other worker |
1165 |
dl |
1.64 |
* threads that might steal them, or zero if this thread is not |
1166 |
|
|
* operating in a ForkJoinPool. This value may be useful for |
1167 |
jsr166 |
1.1 |
* heuristic decisions about whether to fork other tasks. In many |
1168 |
|
|
* usages of ForkJoinTasks, at steady state, each worker should |
1169 |
|
|
* aim to maintain a small constant surplus (for example, 3) of |
1170 |
|
|
* tasks, and to process computations locally if this threshold is |
1171 |
|
|
* exceeded. |
1172 |
|
|
* |
1173 |
|
|
* @return the surplus number of tasks, which may be negative |
1174 |
|
|
*/ |
1175 |
|
|
public static int getSurplusQueuedTaskCount() { |
1176 |
dl |
1.66 |
return ForkJoinPool.getSurplusQueuedTaskCount(); |
1177 |
jsr166 |
1.1 |
} |
1178 |
|
|
|
1179 |
|
|
// Extension methods |
1180 |
|
|
|
1181 |
|
|
/** |
1182 |
jsr166 |
1.4 |
* Returns the result that would be returned by {@link #join}, even |
1183 |
|
|
* if this task completed abnormally, or {@code null} if this task |
1184 |
|
|
* is not known to have been completed. This method is designed |
1185 |
|
|
* to aid debugging, as well as to support extensions. Its use in |
1186 |
|
|
* any other context is discouraged. |
1187 |
jsr166 |
1.1 |
* |
1188 |
jsr166 |
1.4 |
* @return the result, or {@code null} if not completed |
1189 |
jsr166 |
1.1 |
*/ |
1190 |
|
|
public abstract V getRawResult(); |
1191 |
|
|
|
1192 |
|
|
/** |
1193 |
|
|
* Forces the given value to be returned as a result. This method |
1194 |
|
|
* is designed to support extensions, and should not in general be |
1195 |
|
|
* called otherwise. |
1196 |
|
|
* |
1197 |
|
|
* @param value the value |
1198 |
|
|
*/ |
1199 |
|
|
protected abstract void setRawResult(V value); |
1200 |
|
|
|
1201 |
|
|
/** |
1202 |
dl |
1.62 |
* Immediately performs the base action of this task and returns |
1203 |
|
|
* true if, upon return from this method, this task is guaranteed |
1204 |
dl |
1.122 |
* to have completed. This method may return false otherwise, to |
1205 |
|
|
* indicate that this task is not necessarily complete (or is not |
1206 |
|
|
* known to be complete), for example in asynchronous actions that |
1207 |
|
|
* require explicit invocations of completion methods. This method |
1208 |
|
|
* may also throw an (unchecked) exception to indicate abnormal |
1209 |
|
|
* exit. This method is designed to support extensions, and should |
1210 |
|
|
* not in general be called otherwise. |
1211 |
jsr166 |
1.1 |
* |
1212 |
dl |
1.62 |
* @return {@code true} if this task is known to have completed normally |
1213 |
jsr166 |
1.1 |
*/ |
1214 |
|
|
protected abstract boolean exec(); |
1215 |
|
|
|
1216 |
|
|
/** |
1217 |
jsr166 |
1.5 |
* Returns, but does not unschedule or execute, a task queued by |
1218 |
|
|
* the current thread but not yet executed, if one is immediately |
1219 |
dl |
1.66 |
* available. There is no guarantee that this task will actually |
1220 |
|
|
* be polled or executed next. Conversely, this method may return |
1221 |
|
|
* null even if a task exists but cannot be accessed without |
1222 |
|
|
* contention with other threads. This method is designed |
1223 |
jsr166 |
1.5 |
* primarily to support extensions, and is unlikely to be useful |
1224 |
jsr166 |
1.6 |
* otherwise. |
1225 |
|
|
* |
1226 |
jsr166 |
1.4 |
* @return the next task, or {@code null} if none are available |
1227 |
jsr166 |
1.1 |
*/ |
1228 |
|
|
protected static ForkJoinTask<?> peekNextLocalTask() { |
1229 |
dl |
1.66 |
Thread t; ForkJoinPool.WorkQueue q; |
1230 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
1231 |
|
|
q = ((ForkJoinWorkerThread)t).workQueue; |
1232 |
|
|
else |
1233 |
|
|
q = ForkJoinPool.commonSubmitterQueue(); |
1234 |
|
|
return (q == null) ? null : q.peek(); |
1235 |
jsr166 |
1.1 |
} |
1236 |
|
|
|
1237 |
|
|
/** |
1238 |
|
|
* Unschedules and returns, without executing, the next task |
1239 |
dl |
1.64 |
* queued by the current thread but not yet executed, if the |
1240 |
|
|
* current thread is operating in a ForkJoinPool. This method is |
1241 |
|
|
* designed primarily to support extensions, and is unlikely to be |
1242 |
|
|
* useful otherwise. |
1243 |
jsr166 |
1.1 |
* |
1244 |
jsr166 |
1.4 |
* @return the next task, or {@code null} if none are available |
1245 |
jsr166 |
1.1 |
*/ |
1246 |
|
|
protected static ForkJoinTask<?> pollNextLocalTask() { |
1247 |
dl |
1.64 |
Thread t; |
1248 |
|
|
return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1249 |
|
|
((ForkJoinWorkerThread)t).workQueue.nextLocalTask() : |
1250 |
|
|
null; |
1251 |
jsr166 |
1.1 |
} |
1252 |
|
|
|
1253 |
|
|
/** |
1254 |
dl |
1.64 |
* If the current thread is operating in a ForkJoinPool, |
1255 |
|
|
* unschedules and returns, without executing, the next task |
1256 |
jsr166 |
1.1 |
* queued by the current thread but not yet executed, if one is |
1257 |
|
|
* available, or if not available, a task that was forked by some |
1258 |
|
|
* other thread, if available. Availability may be transient, so a |
1259 |
dl |
1.64 |
* {@code null} result does not necessarily imply quiescence of |
1260 |
|
|
* the pool this task is operating in. This method is designed |
1261 |
jsr166 |
1.1 |
* primarily to support extensions, and is unlikely to be useful |
1262 |
jsr166 |
1.6 |
* otherwise. |
1263 |
|
|
* |
1264 |
jsr166 |
1.4 |
* @return a task, or {@code null} if none are available |
1265 |
jsr166 |
1.1 |
*/ |
1266 |
|
|
protected static ForkJoinTask<?> pollTask() { |
1267 |
dl |
1.64 |
Thread t; ForkJoinWorkerThread wt; |
1268 |
|
|
return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1269 |
|
|
(wt = (ForkJoinWorkerThread)t).pool.nextTaskFor(wt.workQueue) : |
1270 |
|
|
null; |
1271 |
dl |
1.54 |
} |
1272 |
|
|
|
1273 |
dl |
1.94 |
/** |
1274 |
|
|
* If the current thread is operating in a ForkJoinPool, |
1275 |
|
|
* unschedules and returns, without executing, a task externally |
1276 |
|
|
* submitted to the pool, if one is available. Availability may be |
1277 |
|
|
* transient, so a {@code null} result does not necessarily imply |
1278 |
|
|
* quiescence of the pool. This method is designed primarily to |
1279 |
|
|
* support extensions, and is unlikely to be useful otherwise. |
1280 |
|
|
* |
1281 |
|
|
* @return a task, or {@code null} if none are available |
1282 |
jsr166 |
1.107 |
* @since 9 |
1283 |
dl |
1.94 |
*/ |
1284 |
|
|
protected static ForkJoinTask<?> pollSubmission() { |
1285 |
dl |
1.96 |
Thread t; |
1286 |
dl |
1.94 |
return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1287 |
dl |
1.96 |
((ForkJoinWorkerThread)t).pool.pollSubmission() : null; |
1288 |
dl |
1.94 |
} |
1289 |
|
|
|
1290 |
dl |
1.60 |
// tag operations |
1291 |
dl |
1.54 |
|
1292 |
|
|
/** |
1293 |
dl |
1.60 |
* Returns the tag for this task. |
1294 |
dl |
1.54 |
* |
1295 |
dl |
1.60 |
* @return the tag for this task |
1296 |
dl |
1.54 |
* @since 1.8 |
1297 |
|
|
*/ |
1298 |
dl |
1.60 |
public final short getForkJoinTaskTag() { |
1299 |
|
|
return (short)status; |
1300 |
dl |
1.54 |
} |
1301 |
|
|
|
1302 |
|
|
/** |
1303 |
jsr166 |
1.102 |
* Atomically sets the tag value for this task and returns the old value. |
1304 |
dl |
1.54 |
* |
1305 |
jsr166 |
1.102 |
* @param newValue the new tag value |
1306 |
dl |
1.60 |
* @return the previous value of the tag |
1307 |
dl |
1.54 |
* @since 1.8 |
1308 |
|
|
*/ |
1309 |
jsr166 |
1.102 |
public final short setForkJoinTaskTag(short newValue) { |
1310 |
dl |
1.54 |
for (int s;;) { |
1311 |
dl |
1.118 |
if (STATUS.weakCompareAndSet(this, s = status, |
1312 |
|
|
(s & ~SMASK) | (newValue & SMASK))) |
1313 |
dl |
1.60 |
return (short)s; |
1314 |
dl |
1.54 |
} |
1315 |
|
|
} |
1316 |
|
|
|
1317 |
|
|
/** |
1318 |
dl |
1.60 |
* Atomically conditionally sets the tag value for this task. |
1319 |
|
|
* Among other applications, tags can be used as visit markers |
1320 |
dl |
1.61 |
* in tasks operating on graphs, as in methods that check: {@code |
1321 |
dl |
1.60 |
* if (task.compareAndSetForkJoinTaskTag((short)0, (short)1))} |
1322 |
|
|
* before processing, otherwise exiting because the node has |
1323 |
|
|
* already been visited. |
1324 |
dl |
1.54 |
* |
1325 |
jsr166 |
1.102 |
* @param expect the expected tag value |
1326 |
|
|
* @param update the new tag value |
1327 |
jsr166 |
1.76 |
* @return {@code true} if successful; i.e., the current value was |
1328 |
jsr166 |
1.102 |
* equal to {@code expect} and was changed to {@code update}. |
1329 |
dl |
1.54 |
* @since 1.8 |
1330 |
|
|
*/ |
1331 |
jsr166 |
1.102 |
public final boolean compareAndSetForkJoinTaskTag(short expect, short update) { |
1332 |
dl |
1.54 |
for (int s;;) { |
1333 |
jsr166 |
1.102 |
if ((short)(s = status) != expect) |
1334 |
dl |
1.54 |
return false; |
1335 |
dl |
1.118 |
if (STATUS.weakCompareAndSet(this, s, |
1336 |
|
|
(s & ~SMASK) | (update & SMASK))) |
1337 |
dl |
1.54 |
return true; |
1338 |
|
|
} |
1339 |
jsr166 |
1.1 |
} |
1340 |
|
|
|
1341 |
jsr166 |
1.5 |
/** |
1342 |
jsr166 |
1.95 |
* Adapter for Runnables. This implements RunnableFuture |
1343 |
jsr166 |
1.5 |
* to be compliant with AbstractExecutorService constraints |
1344 |
|
|
* when used in ForkJoinPool. |
1345 |
|
|
*/ |
1346 |
|
|
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
1347 |
|
|
implements RunnableFuture<T> { |
1348 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1349 |
jsr166 |
1.5 |
final Runnable runnable; |
1350 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1351 |
jsr166 |
1.5 |
T result; |
1352 |
|
|
AdaptedRunnable(Runnable runnable, T result) { |
1353 |
|
|
if (runnable == null) throw new NullPointerException(); |
1354 |
|
|
this.runnable = runnable; |
1355 |
dl |
1.59 |
this.result = result; // OK to set this even before completion |
1356 |
jsr166 |
1.5 |
} |
1357 |
dl |
1.59 |
public final T getRawResult() { return result; } |
1358 |
|
|
public final void setRawResult(T v) { result = v; } |
1359 |
|
|
public final boolean exec() { runnable.run(); return true; } |
1360 |
|
|
public final void run() { invoke(); } |
1361 |
jsr166 |
1.116 |
public String toString() { |
1362 |
|
|
return super.toString() + "[Wrapped task = " + runnable + "]"; |
1363 |
|
|
} |
1364 |
dl |
1.59 |
private static final long serialVersionUID = 5232453952276885070L; |
1365 |
|
|
} |
1366 |
|
|
|
1367 |
|
|
/** |
1368 |
jsr166 |
1.99 |
* Adapter for Runnables without results. |
1369 |
dl |
1.59 |
*/ |
1370 |
|
|
static final class AdaptedRunnableAction extends ForkJoinTask<Void> |
1371 |
|
|
implements RunnableFuture<Void> { |
1372 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1373 |
dl |
1.59 |
final Runnable runnable; |
1374 |
|
|
AdaptedRunnableAction(Runnable runnable) { |
1375 |
|
|
if (runnable == null) throw new NullPointerException(); |
1376 |
|
|
this.runnable = runnable; |
1377 |
jsr166 |
1.5 |
} |
1378 |
dl |
1.59 |
public final Void getRawResult() { return null; } |
1379 |
|
|
public final void setRawResult(Void v) { } |
1380 |
|
|
public final boolean exec() { runnable.run(); return true; } |
1381 |
|
|
public final void run() { invoke(); } |
1382 |
jsr166 |
1.116 |
public String toString() { |
1383 |
|
|
return super.toString() + "[Wrapped task = " + runnable + "]"; |
1384 |
|
|
} |
1385 |
jsr166 |
1.5 |
private static final long serialVersionUID = 5232453952276885070L; |
1386 |
|
|
} |
1387 |
|
|
|
1388 |
|
|
/** |
1389 |
jsr166 |
1.99 |
* Adapter for Runnables in which failure forces worker exception. |
1390 |
dl |
1.73 |
*/ |
1391 |
|
|
static final class RunnableExecuteAction extends ForkJoinTask<Void> { |
1392 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1393 |
dl |
1.73 |
final Runnable runnable; |
1394 |
|
|
RunnableExecuteAction(Runnable runnable) { |
1395 |
|
|
if (runnable == null) throw new NullPointerException(); |
1396 |
|
|
this.runnable = runnable; |
1397 |
|
|
} |
1398 |
|
|
public final Void getRawResult() { return null; } |
1399 |
|
|
public final void setRawResult(Void v) { } |
1400 |
|
|
public final boolean exec() { runnable.run(); return true; } |
1401 |
|
|
void internalPropagateException(Throwable ex) { |
1402 |
|
|
rethrow(ex); // rethrow outside exec() catches. |
1403 |
|
|
} |
1404 |
|
|
private static final long serialVersionUID = 5232453952276885070L; |
1405 |
|
|
} |
1406 |
|
|
|
1407 |
|
|
/** |
1408 |
jsr166 |
1.99 |
* Adapter for Callables. |
1409 |
jsr166 |
1.5 |
*/ |
1410 |
|
|
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
1411 |
|
|
implements RunnableFuture<T> { |
1412 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1413 |
jsr166 |
1.6 |
final Callable<? extends T> callable; |
1414 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1415 |
jsr166 |
1.5 |
T result; |
1416 |
jsr166 |
1.6 |
AdaptedCallable(Callable<? extends T> callable) { |
1417 |
jsr166 |
1.5 |
if (callable == null) throw new NullPointerException(); |
1418 |
|
|
this.callable = callable; |
1419 |
|
|
} |
1420 |
dl |
1.59 |
public final T getRawResult() { return result; } |
1421 |
|
|
public final void setRawResult(T v) { result = v; } |
1422 |
|
|
public final boolean exec() { |
1423 |
jsr166 |
1.5 |
try { |
1424 |
|
|
result = callable.call(); |
1425 |
|
|
return true; |
1426 |
|
|
} catch (RuntimeException rex) { |
1427 |
|
|
throw rex; |
1428 |
|
|
} catch (Exception ex) { |
1429 |
|
|
throw new RuntimeException(ex); |
1430 |
|
|
} |
1431 |
|
|
} |
1432 |
dl |
1.59 |
public final void run() { invoke(); } |
1433 |
jsr166 |
1.116 |
public String toString() { |
1434 |
|
|
return super.toString() + "[Wrapped task = " + callable + "]"; |
1435 |
|
|
} |
1436 |
jsr166 |
1.117 |
private static final long serialVersionUID = 2838392045355241008L; |
1437 |
jsr166 |
1.5 |
} |
1438 |
jsr166 |
1.2 |
|
1439 |
|
|
/** |
1440 |
jsr166 |
1.6 |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1441 |
|
|
* method of the given {@code Runnable} as its action, and returns |
1442 |
|
|
* a null result upon {@link #join}. |
1443 |
jsr166 |
1.2 |
* |
1444 |
|
|
* @param runnable the runnable action |
1445 |
|
|
* @return the task |
1446 |
|
|
*/ |
1447 |
jsr166 |
1.6 |
public static ForkJoinTask<?> adapt(Runnable runnable) { |
1448 |
dl |
1.59 |
return new AdaptedRunnableAction(runnable); |
1449 |
jsr166 |
1.2 |
} |
1450 |
|
|
|
1451 |
|
|
/** |
1452 |
jsr166 |
1.6 |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1453 |
|
|
* method of the given {@code Runnable} as its action, and returns |
1454 |
|
|
* the given result upon {@link #join}. |
1455 |
jsr166 |
1.2 |
* |
1456 |
|
|
* @param runnable the runnable action |
1457 |
|
|
* @param result the result upon completion |
1458 |
jsr166 |
1.82 |
* @param <T> the type of the result |
1459 |
jsr166 |
1.2 |
* @return the task |
1460 |
|
|
*/ |
1461 |
|
|
public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) { |
1462 |
jsr166 |
1.5 |
return new AdaptedRunnable<T>(runnable, result); |
1463 |
jsr166 |
1.2 |
} |
1464 |
|
|
|
1465 |
|
|
/** |
1466 |
jsr166 |
1.6 |
* Returns a new {@code ForkJoinTask} that performs the {@code call} |
1467 |
|
|
* method of the given {@code Callable} as its action, and returns |
1468 |
|
|
* its result upon {@link #join}, translating any checked exceptions |
1469 |
|
|
* encountered into {@code RuntimeException}. |
1470 |
jsr166 |
1.2 |
* |
1471 |
|
|
* @param callable the callable action |
1472 |
jsr166 |
1.82 |
* @param <T> the type of the callable's result |
1473 |
jsr166 |
1.2 |
* @return the task |
1474 |
|
|
*/ |
1475 |
jsr166 |
1.6 |
public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) { |
1476 |
jsr166 |
1.5 |
return new AdaptedCallable<T>(callable); |
1477 |
jsr166 |
1.2 |
} |
1478 |
|
|
|
1479 |
jsr166 |
1.1 |
// Serialization support |
1480 |
|
|
|
1481 |
|
|
private static final long serialVersionUID = -7721805057305804111L; |
1482 |
|
|
|
1483 |
|
|
/** |
1484 |
jsr166 |
1.53 |
* Saves this task to a stream (that is, serializes it). |
1485 |
jsr166 |
1.1 |
* |
1486 |
jsr166 |
1.83 |
* @param s the stream |
1487 |
jsr166 |
1.84 |
* @throws java.io.IOException if an I/O error occurs |
1488 |
jsr166 |
1.1 |
* @serialData the current run status and the exception thrown |
1489 |
jsr166 |
1.4 |
* during execution, or {@code null} if none |
1490 |
jsr166 |
1.1 |
*/ |
1491 |
|
|
private void writeObject(java.io.ObjectOutputStream s) |
1492 |
|
|
throws java.io.IOException { |
1493 |
|
|
s.defaultWriteObject(); |
1494 |
|
|
s.writeObject(getException()); |
1495 |
|
|
} |
1496 |
|
|
|
1497 |
|
|
/** |
1498 |
jsr166 |
1.53 |
* Reconstitutes this task from a stream (that is, deserializes it). |
1499 |
jsr166 |
1.83 |
* @param s the stream |
1500 |
jsr166 |
1.84 |
* @throws ClassNotFoundException if the class of a serialized object |
1501 |
|
|
* could not be found |
1502 |
|
|
* @throws java.io.IOException if an I/O error occurs |
1503 |
jsr166 |
1.1 |
*/ |
1504 |
|
|
private void readObject(java.io.ObjectInputStream s) |
1505 |
|
|
throws java.io.IOException, ClassNotFoundException { |
1506 |
|
|
s.defaultReadObject(); |
1507 |
|
|
Object ex = s.readObject(); |
1508 |
|
|
if (ex != null) |
1509 |
dl |
1.45 |
setExceptionalCompletion((Throwable)ex); |
1510 |
jsr166 |
1.1 |
} |
1511 |
|
|
|
1512 |
dl |
1.109 |
// VarHandle mechanics |
1513 |
|
|
private static final VarHandle STATUS; |
1514 |
dl |
1.45 |
static { |
1515 |
jsr166 |
1.1 |
try { |
1516 |
dl |
1.109 |
MethodHandles.Lookup l = MethodHandles.lookup(); |
1517 |
|
|
STATUS = l.findVarHandle(ForkJoinTask.class, "status", int.class); |
1518 |
jsr166 |
1.91 |
} catch (ReflectiveOperationException e) { |
1519 |
jsr166 |
1.120 |
throw new ExceptionInInitializerError(e); |
1520 |
jsr166 |
1.1 |
} |
1521 |
|
|
} |
1522 |
dl |
1.45 |
|
1523 |
jsr166 |
1.1 |
} |