1 |
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 |
*/ |
6 |
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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; |
11 |
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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 |
1.124 |
import java.util.concurrent.locks.LockSupport; |
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}. |
22 |
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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 |
34 |
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* {@link #join}, or derivatives such as {@link |
35 |
jsr166 |
1.27 |
* #invokeAll(ForkJoinTask...) invokeAll}. However, this class also |
36 |
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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. |
39 |
jsr166 |
1.1 |
* |
40 |
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) |
43 |
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 |
45 |
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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 |
49 |
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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 |
52 |
jsr166 |
1.68 |
* not perform blocking I/O, and should ideally access variables that |
53 |
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 |
70 |
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 |
74 |
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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 |
77 |
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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} |
85 |
dl |
1.16 |
* conventions. Method {@link #invoke} is semantically |
86 |
jsr166 |
1.8 |
* equivalent to {@code fork(); join()} but always attempts to begin |
87 |
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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 |
89 |
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. |
91 |
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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. |
94 |
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* |
95 |
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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* |
102 |
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 |
104 |
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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 |
dl |
1.130 |
* <p>By default, method {@link #cancel} ignores its {@code |
115 |
dl |
1.131 |
* mayInterruptIfRunning} argument, separating task cancellation from |
116 |
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* the interruption status of threads running tasks. However, the |
117 |
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* method is overridable to accommodate cases in which running tasks |
118 |
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* must be cancelled using interrupts. This may arise when adapting |
119 |
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* Callables that cannot check {@code isCancelled()} task status. |
120 |
dl |
1.132 |
* Tasks constructed with the {@link #adaptInterruptible} adaptor |
121 |
dl |
1.131 |
* track and interrupt the running thread upon {@code |
122 |
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* cancel(true)}. Reliable usage requires awareness of potential |
123 |
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* consequences: Method bodies should ignore stray interrupts to cope |
124 |
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* with the inherent possibility that a late interrupt issued by |
125 |
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* another thread after a given task has completed may (inadvertently) |
126 |
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* interrupt some future task. Further, interruptible tasks should not |
127 |
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* in general create subtasks, because an interrupt intended for a |
128 |
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* given task may be consumed by one of its subtasks, or vice versa. |
129 |
dl |
1.130 |
* |
130 |
jsr166 |
1.6 |
* <p>The ForkJoinTask class is not usually directly subclassed. |
131 |
jsr166 |
1.1 |
* Instead, you subclass one of the abstract classes that support a |
132 |
jsr166 |
1.6 |
* particular style of fork/join processing, typically {@link |
133 |
dl |
1.62 |
* RecursiveAction} for most computations that do not return results, |
134 |
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* {@link RecursiveTask} for those that do, and {@link |
135 |
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* CountedCompleter} for those in which completed actions trigger |
136 |
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* other actions. Normally, a concrete ForkJoinTask subclass declares |
137 |
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* fields comprising its parameters, established in a constructor, and |
138 |
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* then defines a {@code compute} method that somehow uses the control |
139 |
dl |
1.64 |
* methods supplied by this base class. |
140 |
jsr166 |
1.1 |
* |
141 |
dl |
1.38 |
* <p>Method {@link #join} and its variants are appropriate for use |
142 |
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* only when completion dependencies are acyclic; that is, the |
143 |
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* parallel computation can be described as a directed acyclic graph |
144 |
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* (DAG). Otherwise, executions may encounter a form of deadlock as |
145 |
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* tasks cyclically wait for each other. However, this framework |
146 |
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* supports other methods and techniques (for example the use of |
147 |
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* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that |
148 |
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* may be of use in constructing custom subclasses for problems that |
149 |
jsr166 |
1.79 |
* are not statically structured as DAGs. To support such usages, a |
150 |
dl |
1.63 |
* ForkJoinTask may be atomically <em>tagged</em> with a {@code short} |
151 |
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* value using {@link #setForkJoinTaskTag} or {@link |
152 |
dl |
1.60 |
* #compareAndSetForkJoinTaskTag} and checked using {@link |
153 |
dl |
1.63 |
* #getForkJoinTaskTag}. The ForkJoinTask implementation does not use |
154 |
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* these {@code protected} methods or tags for any purpose, but they |
155 |
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* may be of use in the construction of specialized subclasses. For |
156 |
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* example, parallel graph traversals can use the supplied methods to |
157 |
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* avoid revisiting nodes/tasks that have already been processed. |
158 |
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* (Method names for tagging are bulky in part to encourage definition |
159 |
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* of methods that reflect their usage patterns.) |
160 |
dl |
1.38 |
* |
161 |
jsr166 |
1.7 |
* <p>Most base support methods are {@code final}, to prevent |
162 |
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* overriding of implementations that are intrinsically tied to the |
163 |
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* underlying lightweight task scheduling framework. Developers |
164 |
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* creating new basic styles of fork/join processing should minimally |
165 |
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* implement {@code protected} methods {@link #exec}, {@link |
166 |
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* #setRawResult}, and {@link #getRawResult}, while also introducing |
167 |
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* an abstract computational method that can be implemented in its |
168 |
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* subclasses, possibly relying on other {@code protected} methods |
169 |
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* provided by this class. |
170 |
jsr166 |
1.1 |
* |
171 |
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* <p>ForkJoinTasks should perform relatively small amounts of |
172 |
jsr166 |
1.7 |
* computation. Large tasks should be split into smaller subtasks, |
173 |
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* usually via recursive decomposition. As a very rough rule of thumb, |
174 |
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* a task should perform more than 100 and less than 10000 basic |
175 |
dl |
1.40 |
* computational steps, and should avoid indefinite looping. If tasks |
176 |
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* are too big, then parallelism cannot improve throughput. If too |
177 |
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* small, then memory and internal task maintenance overhead may |
178 |
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* overwhelm processing. |
179 |
jsr166 |
1.1 |
* |
180 |
jsr166 |
1.8 |
* <p>This class provides {@code adapt} methods for {@link Runnable} |
181 |
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* and {@link Callable}, that may be of use when mixing execution of |
182 |
dl |
1.16 |
* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are |
183 |
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* of this form, consider using a pool constructed in <em>asyncMode</em>. |
184 |
jsr166 |
1.6 |
* |
185 |
jsr166 |
1.7 |
* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
186 |
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* used in extensions such as remote execution frameworks. It is |
187 |
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* sensible to serialize tasks only before or after, but not during, |
188 |
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* execution. Serialization is not relied on during execution itself. |
189 |
jsr166 |
1.1 |
* |
190 |
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* @since 1.7 |
191 |
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* @author Doug Lea |
192 |
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*/ |
193 |
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public abstract class ForkJoinTask<V> implements Future<V>, Serializable { |
194 |
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|
195 |
dl |
1.13 |
/* |
196 |
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* See the internal documentation of class ForkJoinPool for a |
197 |
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* general implementation overview. ForkJoinTasks are mainly |
198 |
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* responsible for maintaining their "status" field amidst relays |
199 |
jsr166 |
1.51 |
* to methods in ForkJoinWorkerThread and ForkJoinPool. |
200 |
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* |
201 |
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* The methods of this class are more-or-less layered into |
202 |
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* (1) basic status maintenance |
203 |
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* (2) execution and awaiting completion |
204 |
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* (3) user-level methods that additionally report results. |
205 |
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* This is sometimes hard to see because this file orders exported |
206 |
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* methods in a way that flows well in javadocs. |
207 |
dl |
1.118 |
* |
208 |
dl |
1.124 |
* Revision notes: The use of "Aux" field replaces previous |
209 |
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* reliance on a table to hold exceptions and synchronized blocks |
210 |
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* and monitors to wait for completion. |
211 |
dl |
1.118 |
*/ |
212 |
jsr166 |
1.1 |
|
213 |
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/** |
214 |
dl |
1.124 |
* Nodes for threads waiting for completion, or holding a thrown |
215 |
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* exception (never both). Waiting threads prepend nodes |
216 |
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* Treiber-stack-style. Signallers detach and unpark |
217 |
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* waiters. Cancelled waiters try to unsplice. |
218 |
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*/ |
219 |
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static final class Aux { |
220 |
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final Thread thread; |
221 |
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final Throwable ex; // null if a waiter |
222 |
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Aux next; // accessed only via memory-acquire chains |
223 |
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Aux(Thread thread, Throwable ex) { |
224 |
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this.thread = thread; |
225 |
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this.ex = ex; |
226 |
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} |
227 |
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final boolean casNext(Aux c, Aux v) { // used only in cancellation |
228 |
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return NEXT.compareAndSet(this, c, v); |
229 |
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} |
230 |
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private static final VarHandle NEXT; |
231 |
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static { |
232 |
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try { |
233 |
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NEXT = MethodHandles.lookup() |
234 |
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.findVarHandle(Aux.class, "next", Aux.class); |
235 |
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} catch (ReflectiveOperationException e) { |
236 |
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throw new ExceptionInInitializerError(e); |
237 |
dl |
1.13 |
} |
238 |
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} |
239 |
jsr166 |
1.1 |
} |
240 |
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|
241 |
dl |
1.124 |
/* |
242 |
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* The status field holds bits packed into a single int to ensure |
243 |
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* atomicity. Status is initially zero, and takes on nonnegative |
244 |
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* values until completed, upon which it holds (sign bit) DONE, |
245 |
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* possibly with ABNORMAL (cancelled or exceptional) and THROWN |
246 |
dl |
1.128 |
* (in which case an exception has been stored). A value of |
247 |
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* ABNORMAL without DONE signifies an interrupted wait. These |
248 |
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* control bits occupy only (some of) the upper half (16 bits) of |
249 |
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* status field. The lower bits are used for user-defined tags. |
250 |
jsr166 |
1.1 |
*/ |
251 |
dl |
1.134 |
private static final int DONE = 1 << 31; // must be negative |
252 |
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private static final int ABNORMAL = 1 << 16; |
253 |
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private static final int THROWN = 1 << 17; |
254 |
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private static final int SMASK = 0xffff; // short bits for tags |
255 |
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private static final int UNCOMPENSATE = 1 << 16; // helpJoin return sentinel |
256 |
dl |
1.124 |
|
257 |
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// Fields |
258 |
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volatile int status; // accessed directly by pool and workers |
259 |
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private transient volatile Aux aux; // either waiters or thrown Exception |
260 |
dl |
1.128 |
|
261 |
dl |
1.124 |
// Support for atomic operations |
262 |
|
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private static final VarHandle STATUS; |
263 |
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private static final VarHandle AUX; |
264 |
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private int getAndBitwiseOrStatus(int v) { |
265 |
|
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return (int)STATUS.getAndBitwiseOr(this, v); |
266 |
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} |
267 |
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private boolean casStatus(int c, int v) { |
268 |
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return STATUS.weakCompareAndSet(this, c, v); |
269 |
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} |
270 |
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private boolean casAux(Aux c, Aux v) { |
271 |
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return AUX.compareAndSet(this, c, v); |
272 |
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} |
273 |
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|
274 |
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/** Removes and unparks waiters */ |
275 |
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private void signalWaiters() { |
276 |
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for (Aux a; (a = aux) != null && a.ex == null; ) { |
277 |
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if (casAux(a, null)) { // detach entire list |
278 |
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for (Thread t; a != null; a = a.next) { |
279 |
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if ((t = a.thread) != Thread.currentThread() && t != null) |
280 |
|
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LockSupport.unpark(t); // don't self-signal |
281 |
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} |
282 |
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break; |
283 |
dl |
1.54 |
} |
284 |
jsr166 |
1.1 |
} |
285 |
|
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} |
286 |
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|
287 |
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/** |
288 |
dl |
1.124 |
* Possibly blocks until task is done or interrupted or timed out. |
289 |
dl |
1.87 |
* |
290 |
dl |
1.124 |
* @param interruptible true if wait can be cancelled by interrupt |
291 |
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* @param deadline if non-zero use timed waits and possibly timeout |
292 |
dl |
1.134 |
* @param pool if nonnull pool to uncompensate after unblocking |
293 |
dl |
1.128 |
* @return status on exit, or ABNORMAL if interrupted while waiting |
294 |
dl |
1.124 |
*/ |
295 |
dl |
1.134 |
private int awaitDone(boolean interruptible, long deadline, |
296 |
dl |
1.126 |
ForkJoinPool pool) { |
297 |
dl |
1.134 |
int s; |
298 |
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boolean interrupted = false, queued = false, parked = false; |
299 |
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Aux node = null; |
300 |
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while ((s = status) >= 0) { |
301 |
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Aux a; long ns; |
302 |
|
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if (parked && Thread.interrupted()) { |
303 |
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if (interruptible) { |
304 |
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s = ABNORMAL; |
305 |
dl |
1.124 |
break; |
306 |
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} |
307 |
dl |
1.134 |
interrupted = true; |
308 |
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} |
309 |
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else if (queued) { |
310 |
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if (deadline != 0L) { |
311 |
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if ((ns = deadline - System.nanoTime()) <= 0L) |
312 |
dl |
1.126 |
break; |
313 |
dl |
1.134 |
LockSupport.parkNanos(ns); |
314 |
dl |
1.124 |
} |
315 |
dl |
1.128 |
else |
316 |
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LockSupport.park(); |
317 |
dl |
1.134 |
parked = true; |
318 |
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} |
319 |
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else if (node != null) { |
320 |
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if ((a = aux) != null && a.ex != null) |
321 |
|
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Thread.onSpinWait(); // exception in progress |
322 |
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else if (queued = casAux(node.next = a, node)) |
323 |
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LockSupport.setCurrentBlocker(this); |
324 |
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} |
325 |
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else { |
326 |
|
|
try { |
327 |
|
|
node = new Aux(Thread.currentThread(), null); |
328 |
|
|
} catch (Throwable ex) { // try to cancel if cannot create |
329 |
|
|
casStatus(s, s | (DONE | ABNORMAL)); |
330 |
|
|
} |
331 |
dl |
1.87 |
} |
332 |
dl |
1.128 |
} |
333 |
dl |
1.134 |
if (pool != null) |
334 |
|
|
pool.uncompensate(); |
335 |
|
|
|
336 |
dl |
1.128 |
if (queued) { |
337 |
|
|
LockSupport.setCurrentBlocker(null); |
338 |
dl |
1.134 |
if (s >= 0) { // cancellation similar to AbstractQueuedSynchronizer |
339 |
dl |
1.128 |
outer: for (Aux a; (a = aux) != null && a.ex == null; ) { |
340 |
|
|
for (Aux trail = null;;) { |
341 |
|
|
Aux next = a.next; |
342 |
|
|
if (a == node) { |
343 |
|
|
if (trail != null) |
344 |
|
|
trail.casNext(trail, next); |
345 |
|
|
else if (casAux(a, next)) |
346 |
|
|
break outer; // cannot be re-encountered |
347 |
|
|
break; // restart |
348 |
|
|
} else { |
349 |
|
|
trail = a; |
350 |
|
|
if ((a = next) == null) |
351 |
|
|
break outer; |
352 |
dl |
1.126 |
} |
353 |
dl |
1.40 |
} |
354 |
dl |
1.87 |
} |
355 |
dl |
1.118 |
} |
356 |
dl |
1.128 |
else { |
357 |
|
|
signalWaiters(); // help clean or signal |
358 |
|
|
if (interrupted) |
359 |
|
|
Thread.currentThread().interrupt(); |
360 |
|
|
} |
361 |
dl |
1.19 |
} |
362 |
dl |
1.45 |
return s; |
363 |
dl |
1.19 |
} |
364 |
|
|
|
365 |
|
|
/** |
366 |
dl |
1.124 |
* Sets DONE status and wakes up threads waiting to join this task. |
367 |
|
|
* @return status on exit |
368 |
jsr166 |
1.1 |
*/ |
369 |
dl |
1.124 |
private int setDone() { |
370 |
|
|
int s = getAndBitwiseOrStatus(DONE) | DONE; |
371 |
|
|
signalWaiters(); |
372 |
dl |
1.45 |
return s; |
373 |
|
|
} |
374 |
|
|
|
375 |
|
|
/** |
376 |
dl |
1.124 |
* Sets ABNORMAL DONE status unless already done, and wakes up threads |
377 |
|
|
* waiting to join this task. |
378 |
|
|
* @return status on exit |
379 |
dl |
1.118 |
*/ |
380 |
dl |
1.124 |
private int trySetCancelled() { |
381 |
dl |
1.118 |
int s; |
382 |
dl |
1.124 |
do {} while ((s = status) >= 0 && !casStatus(s, s |= (DONE | ABNORMAL))); |
383 |
|
|
signalWaiters(); |
384 |
|
|
return s; |
385 |
dl |
1.118 |
} |
386 |
|
|
|
387 |
|
|
/** |
388 |
dl |
1.124 |
* Records exception and sets ABNORMAL THROWN DONE status unless |
389 |
|
|
* already done, and wakes up threads waiting to join this task. |
390 |
|
|
* If losing a race with setDone or trySetCancelled, the exception |
391 |
|
|
* may be recorded but not reported. |
392 |
dl |
1.54 |
* |
393 |
dl |
1.124 |
* @return status on exit |
394 |
dl |
1.45 |
*/ |
395 |
dl |
1.124 |
final int trySetThrown(Throwable ex) { |
396 |
|
|
Aux h = new Aux(Thread.currentThread(), ex), p = null; |
397 |
|
|
boolean installed = false; |
398 |
|
|
int s; |
399 |
|
|
while ((s = status) >= 0) { |
400 |
|
|
Aux a; |
401 |
|
|
if (!installed && ((a = aux) == null || a.ex == null) && |
402 |
|
|
(installed = casAux(a, h))) |
403 |
|
|
p = a; // list of waiters replaced by h |
404 |
|
|
if (installed && casStatus(s, s |= (DONE | ABNORMAL | THROWN))) |
405 |
|
|
break; |
406 |
|
|
} |
407 |
|
|
for (; p != null; p = p.next) |
408 |
|
|
LockSupport.unpark(p.thread); |
409 |
|
|
return s; |
410 |
jsr166 |
1.1 |
} |
411 |
|
|
|
412 |
|
|
/** |
413 |
dl |
1.124 |
* Records exception unless already done. Overridable in subclasses. |
414 |
dl |
1.54 |
* |
415 |
dl |
1.124 |
* @return status on exit |
416 |
jsr166 |
1.1 |
*/ |
417 |
dl |
1.124 |
int trySetException(Throwable ex) { |
418 |
|
|
return trySetThrown(ex); |
419 |
dl |
1.45 |
} |
420 |
|
|
|
421 |
jsr166 |
1.139 |
/** |
422 |
|
|
* Constructor for subclasses to call. |
423 |
|
|
*/ |
424 |
|
|
public ForkJoinTask() {} |
425 |
|
|
|
426 |
dl |
1.124 |
static boolean isExceptionalStatus(int s) { // needed by subclasses |
427 |
|
|
return (s & THROWN) != 0; |
428 |
dl |
1.45 |
} |
429 |
|
|
|
430 |
|
|
/** |
431 |
dl |
1.124 |
* Unless done, calls exec and records status if completed, but |
432 |
|
|
* doesn't wait for completion otherwise. |
433 |
dl |
1.45 |
* |
434 |
dl |
1.124 |
* @return status on exit from this method |
435 |
dl |
1.45 |
*/ |
436 |
dl |
1.124 |
final int doExec() { |
437 |
|
|
int s; boolean completed; |
438 |
dl |
1.62 |
if ((s = status) >= 0) { |
439 |
|
|
try { |
440 |
dl |
1.124 |
completed = exec(); |
441 |
|
|
} catch (Throwable rex) { |
442 |
|
|
s = trySetException(rex); |
443 |
|
|
completed = false; |
444 |
dl |
1.45 |
} |
445 |
dl |
1.124 |
if (completed) |
446 |
|
|
s = setDone(); |
447 |
dl |
1.45 |
} |
448 |
dl |
1.62 |
return s; |
449 |
|
|
} |
450 |
|
|
|
451 |
|
|
/** |
452 |
dl |
1.134 |
* Helps and/or waits for completion from join, get, or invoke; |
453 |
|
|
* called from either internal or external threads. |
454 |
dl |
1.63 |
* |
455 |
dl |
1.128 |
* @param ran true if task known to have been exec'd |
456 |
dl |
1.134 |
* @param interruptible true if park interruptibly when external |
457 |
|
|
* @param timed true if use timed wait |
458 |
|
|
* @param nanos if timed, timeout value |
459 |
|
|
* @return ABNORMAL if interrupted, else status on exit |
460 |
|
|
*/ |
461 |
|
|
private int awaitJoin(boolean ran, boolean interruptible, boolean timed, |
462 |
|
|
long nanos) { |
463 |
|
|
boolean internal; ForkJoinPool p; ForkJoinPool.WorkQueue q; int s; |
464 |
dl |
1.124 |
Thread t; ForkJoinWorkerThread wt; |
465 |
dl |
1.134 |
if (internal = ((t = Thread.currentThread()) |
466 |
|
|
instanceof ForkJoinWorkerThread)) { |
467 |
dl |
1.124 |
p = (wt = (ForkJoinWorkerThread)t).pool; |
468 |
|
|
q = wt.workQueue; |
469 |
|
|
} |
470 |
dl |
1.126 |
else { |
471 |
|
|
p = ForkJoinPool.common; |
472 |
|
|
q = ForkJoinPool.commonQueue(); |
473 |
dl |
1.134 |
if (interruptible && Thread.interrupted()) |
474 |
|
|
return ABNORMAL; |
475 |
dl |
1.124 |
} |
476 |
dl |
1.134 |
if ((s = status) < 0) |
477 |
|
|
return s; |
478 |
|
|
long deadline = 0L; |
479 |
|
|
if (timed) { |
480 |
|
|
if (nanos <= 0L) |
481 |
|
|
return 0; |
482 |
|
|
else if ((deadline = nanos + System.nanoTime()) == 0L) |
483 |
|
|
deadline = 1L; |
484 |
dl |
1.128 |
} |
485 |
dl |
1.134 |
ForkJoinPool uncompensate = null; |
486 |
|
|
if (q != null && p != null) { // try helping |
487 |
dl |
1.128 |
if ((!timed || p.isSaturated()) && |
488 |
|
|
((this instanceof CountedCompleter) ? |
489 |
dl |
1.134 |
(s = p.helpComplete(this, q, internal)) < 0 : |
490 |
|
|
(q.tryRemove(this, internal) && (s = doExec()) < 0))) |
491 |
dl |
1.128 |
return s; |
492 |
dl |
1.134 |
if (internal) { |
493 |
dl |
1.128 |
if ((s = p.helpJoin(this, q)) < 0) |
494 |
|
|
return s; |
495 |
dl |
1.134 |
if (s == UNCOMPENSATE) |
496 |
|
|
uncompensate = p; |
497 |
|
|
interruptible = false; |
498 |
dl |
1.128 |
} |
499 |
|
|
} |
500 |
dl |
1.134 |
return awaitDone(interruptible, deadline, uncompensate); |
501 |
dl |
1.45 |
} |
502 |
|
|
|
503 |
|
|
/** |
504 |
dl |
1.128 |
* Cancels, ignoring any exceptions thrown by cancel. Cancel is |
505 |
|
|
* spec'ed not to throw any exceptions, but if it does anyway, we |
506 |
|
|
* have no recourse, so guard against this case. |
507 |
dl |
1.54 |
*/ |
508 |
dl |
1.128 |
static final void cancelIgnoringExceptions(Future<?> t) { |
509 |
dl |
1.124 |
if (t != null) { |
510 |
dl |
1.54 |
try { |
511 |
dl |
1.129 |
t.cancel(true); |
512 |
dl |
1.54 |
} catch (Throwable ignore) { |
513 |
|
|
} |
514 |
|
|
} |
515 |
|
|
} |
516 |
|
|
|
517 |
|
|
/** |
518 |
jsr166 |
1.105 |
* Returns a rethrowable exception for this task, if available. |
519 |
|
|
* To provide accurate stack traces, if the exception was not |
520 |
|
|
* thrown by the current thread, we try to create a new exception |
521 |
|
|
* of the same type as the one thrown, but with the recorded |
522 |
|
|
* exception as its cause. If there is no such constructor, we |
523 |
|
|
* instead try to use a no-arg constructor, followed by initCause, |
524 |
|
|
* to the same effect. If none of these apply, or any fail due to |
525 |
|
|
* other exceptions, we return the recorded exception, which is |
526 |
|
|
* still correct, although it may contain a misleading stack |
527 |
|
|
* trace. |
528 |
dl |
1.45 |
* |
529 |
|
|
* @return the exception, or null if none |
530 |
|
|
*/ |
531 |
|
|
private Throwable getThrowableException() { |
532 |
dl |
1.124 |
Throwable ex; Aux a; |
533 |
|
|
if ((a = aux) == null) |
534 |
|
|
ex = null; |
535 |
|
|
else if ((ex = a.ex) != null && a.thread != Thread.currentThread()) { |
536 |
dl |
1.45 |
try { |
537 |
dl |
1.124 |
Constructor<?> noArgCtor = null, oneArgCtor = null; |
538 |
jsr166 |
1.106 |
for (Constructor<?> c : ex.getClass().getConstructors()) { |
539 |
dl |
1.45 |
Class<?>[] ps = c.getParameterTypes(); |
540 |
|
|
if (ps.length == 0) |
541 |
|
|
noArgCtor = c; |
542 |
dl |
1.124 |
else if (ps.length == 1 && ps[0] == Throwable.class) { |
543 |
|
|
oneArgCtor = c; |
544 |
|
|
break; |
545 |
|
|
} |
546 |
dl |
1.45 |
} |
547 |
dl |
1.124 |
if (oneArgCtor != null) |
548 |
|
|
ex = (Throwable)oneArgCtor.newInstance(ex); |
549 |
|
|
else if (noArgCtor != null) { |
550 |
|
|
Throwable rx = (Throwable)noArgCtor.newInstance(); |
551 |
|
|
rx.initCause(ex); |
552 |
|
|
ex = rx; |
553 |
dl |
1.45 |
} |
554 |
|
|
} catch (Exception ignore) { |
555 |
|
|
} |
556 |
|
|
} |
557 |
|
|
return ex; |
558 |
|
|
} |
559 |
|
|
|
560 |
|
|
/** |
561 |
dl |
1.128 |
* Returns exception associated with the given status, or null if none. |
562 |
|
|
*/ |
563 |
|
|
private Throwable getException(int s) { |
564 |
|
|
Throwable ex = null; |
565 |
|
|
if ((s & ABNORMAL) != 0 && |
566 |
|
|
((s & THROWN) == 0 || (ex = getThrowableException()) == null)) |
567 |
|
|
ex = new CancellationException(); |
568 |
|
|
return ex; |
569 |
|
|
} |
570 |
|
|
|
571 |
|
|
/** |
572 |
dl |
1.124 |
* Throws exception associated with the given status, or |
573 |
|
|
* CancellationException if none recorded. |
574 |
dl |
1.45 |
*/ |
575 |
dl |
1.124 |
private void reportException(int s) { |
576 |
|
|
ForkJoinTask.<RuntimeException>uncheckedThrow( |
577 |
|
|
(s & THROWN) != 0 ? getThrowableException() : null); |
578 |
dl |
1.45 |
} |
579 |
|
|
|
580 |
|
|
/** |
581 |
dl |
1.129 |
* Throws exception for (timed or untimed) get, wrapping if |
582 |
|
|
* necessary in an ExecutionException. |
583 |
|
|
*/ |
584 |
dl |
1.134 |
private void reportExecutionException(int s) { |
585 |
dl |
1.129 |
Throwable ex = null; |
586 |
|
|
if (s == ABNORMAL) |
587 |
|
|
ex = new InterruptedException(); |
588 |
|
|
else if (s >= 0) |
589 |
|
|
ex = new TimeoutException(); |
590 |
|
|
else if ((s & THROWN) != 0 && (ex = getThrowableException()) != null) |
591 |
|
|
ex = new ExecutionException(ex); |
592 |
|
|
ForkJoinTask.<RuntimeException>uncheckedThrow(ex); |
593 |
|
|
} |
594 |
|
|
|
595 |
|
|
/** |
596 |
dl |
1.124 |
* A version of "sneaky throw" to relay exceptions in other |
597 |
|
|
* contexts. |
598 |
dl |
1.65 |
*/ |
599 |
jsr166 |
1.78 |
static void rethrow(Throwable ex) { |
600 |
dl |
1.100 |
ForkJoinTask.<RuntimeException>uncheckedThrow(ex); |
601 |
dl |
1.65 |
} |
602 |
|
|
|
603 |
|
|
/** |
604 |
|
|
* The sneaky part of sneaky throw, relying on generics |
605 |
|
|
* limitations to evade compiler complaints about rethrowing |
606 |
dl |
1.124 |
* unchecked exceptions. If argument null, throws |
607 |
|
|
* CancellationException. |
608 |
dl |
1.65 |
*/ |
609 |
|
|
@SuppressWarnings("unchecked") static <T extends Throwable> |
610 |
dl |
1.100 |
void uncheckedThrow(Throwable t) throws T { |
611 |
dl |
1.124 |
if (t == null) |
612 |
|
|
t = new CancellationException(); |
613 |
|
|
throw (T)t; // rely on vacuous cast |
614 |
jsr166 |
1.1 |
} |
615 |
|
|
|
616 |
|
|
// public methods |
617 |
|
|
|
618 |
|
|
/** |
619 |
dl |
1.64 |
* Arranges to asynchronously execute this task in the pool the |
620 |
|
|
* current task is running in, if applicable, or using the {@link |
621 |
dl |
1.67 |
* ForkJoinPool#commonPool()} if not {@link #inForkJoinPool}. While |
622 |
dl |
1.64 |
* it is not necessarily enforced, it is a usage error to fork a |
623 |
|
|
* task more than once unless it has completed and been |
624 |
|
|
* reinitialized. Subsequent modifications to the state of this |
625 |
|
|
* task or any data it operates on are not necessarily |
626 |
|
|
* consistently observable by any thread other than the one |
627 |
|
|
* executing it unless preceded by a call to {@link #join} or |
628 |
|
|
* related methods, or a call to {@link #isDone} returning {@code |
629 |
|
|
* true}. |
630 |
jsr166 |
1.2 |
* |
631 |
jsr166 |
1.6 |
* @return {@code this}, to simplify usage |
632 |
jsr166 |
1.1 |
*/ |
633 |
jsr166 |
1.2 |
public final ForkJoinTask<V> fork() { |
634 |
dl |
1.124 |
Thread t; ForkJoinWorkerThread w; |
635 |
dl |
1.64 |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
636 |
dl |
1.124 |
(w = (ForkJoinWorkerThread)t).workQueue.push(this, w.pool); |
637 |
dl |
1.64 |
else |
638 |
dl |
1.71 |
ForkJoinPool.common.externalPush(this); |
639 |
jsr166 |
1.2 |
return this; |
640 |
jsr166 |
1.1 |
} |
641 |
|
|
|
642 |
|
|
/** |
643 |
jsr166 |
1.115 |
* Returns the result of the computation when it |
644 |
|
|
* {@linkplain #isDone is done}. |
645 |
|
|
* This method differs from {@link #get()} in that abnormal |
646 |
|
|
* completion results in {@code RuntimeException} or {@code Error}, |
647 |
|
|
* not {@code ExecutionException}, and that interrupts of the |
648 |
|
|
* calling thread do <em>not</em> cause the method to abruptly |
649 |
|
|
* return by throwing {@code InterruptedException}. |
650 |
jsr166 |
1.1 |
* |
651 |
|
|
* @return the computed result |
652 |
|
|
*/ |
653 |
|
|
public final V join() { |
654 |
dl |
1.59 |
int s; |
655 |
dl |
1.124 |
if ((s = status) >= 0) |
656 |
dl |
1.134 |
s = awaitJoin(false, false, false, 0L); |
657 |
dl |
1.124 |
if ((s & ABNORMAL) != 0) |
658 |
dl |
1.59 |
reportException(s); |
659 |
|
|
return getRawResult(); |
660 |
jsr166 |
1.1 |
} |
661 |
|
|
|
662 |
|
|
/** |
663 |
|
|
* Commences performing this task, awaits its completion if |
664 |
jsr166 |
1.21 |
* necessary, and returns its result, or throws an (unchecked) |
665 |
dl |
1.20 |
* {@code RuntimeException} or {@code Error} if the underlying |
666 |
|
|
* computation did so. |
667 |
jsr166 |
1.1 |
* |
668 |
|
|
* @return the computed result |
669 |
|
|
*/ |
670 |
|
|
public final V invoke() { |
671 |
dl |
1.59 |
int s; |
672 |
dl |
1.124 |
if ((s = doExec()) >= 0) |
673 |
dl |
1.134 |
s = awaitJoin(true, false, false, 0L); |
674 |
dl |
1.124 |
if ((s & ABNORMAL) != 0) |
675 |
dl |
1.59 |
reportException(s); |
676 |
|
|
return getRawResult(); |
677 |
jsr166 |
1.1 |
} |
678 |
|
|
|
679 |
|
|
/** |
680 |
jsr166 |
1.8 |
* Forks the given tasks, returning when {@code isDone} holds for |
681 |
|
|
* each task or an (unchecked) exception is encountered, in which |
682 |
dl |
1.20 |
* case the exception is rethrown. If more than one task |
683 |
|
|
* encounters an exception, then this method throws any one of |
684 |
|
|
* these exceptions. If any task encounters an exception, the |
685 |
|
|
* other may be cancelled. However, the execution status of |
686 |
|
|
* individual tasks is not guaranteed upon exceptional return. The |
687 |
|
|
* status of each task may be obtained using {@link |
688 |
|
|
* #getException()} and related methods to check if they have been |
689 |
|
|
* cancelled, completed normally or exceptionally, or left |
690 |
|
|
* unprocessed. |
691 |
jsr166 |
1.6 |
* |
692 |
|
|
* @param t1 the first task |
693 |
|
|
* @param t2 the second task |
694 |
|
|
* @throws NullPointerException if any task is null |
695 |
jsr166 |
1.1 |
*/ |
696 |
jsr166 |
1.6 |
public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) { |
697 |
dl |
1.59 |
int s1, s2; |
698 |
dl |
1.124 |
if (t1 == null || t2 == null) |
699 |
|
|
throw new NullPointerException(); |
700 |
jsr166 |
1.1 |
t2.fork(); |
701 |
dl |
1.124 |
if ((s1 = t1.doExec()) >= 0) |
702 |
dl |
1.134 |
s1 = t1.awaitJoin(true, false, false, 0L); |
703 |
dl |
1.128 |
if ((s1 & ABNORMAL) != 0) { |
704 |
|
|
cancelIgnoringExceptions(t2); |
705 |
dl |
1.59 |
t1.reportException(s1); |
706 |
dl |
1.128 |
} |
707 |
dl |
1.134 |
else if (((s2 = t2.awaitJoin(false, false, false, 0L)) & ABNORMAL) != 0) |
708 |
|
|
t2.reportException(s2); |
709 |
jsr166 |
1.1 |
} |
710 |
|
|
|
711 |
|
|
/** |
712 |
jsr166 |
1.6 |
* Forks the given tasks, returning when {@code isDone} holds for |
713 |
jsr166 |
1.8 |
* each task or an (unchecked) exception is encountered, in which |
714 |
dl |
1.20 |
* case the exception is rethrown. If more than one task |
715 |
|
|
* encounters an exception, then this method throws any one of |
716 |
|
|
* these exceptions. If any task encounters an exception, others |
717 |
|
|
* may be cancelled. However, the execution status of individual |
718 |
|
|
* tasks is not guaranteed upon exceptional return. The status of |
719 |
|
|
* each task may be obtained using {@link #getException()} and |
720 |
|
|
* related methods to check if they have been cancelled, completed |
721 |
|
|
* normally or exceptionally, or left unprocessed. |
722 |
jsr166 |
1.6 |
* |
723 |
|
|
* @param tasks the tasks |
724 |
jsr166 |
1.8 |
* @throws NullPointerException if any task is null |
725 |
jsr166 |
1.1 |
*/ |
726 |
|
|
public static void invokeAll(ForkJoinTask<?>... tasks) { |
727 |
|
|
Throwable ex = null; |
728 |
|
|
int last = tasks.length - 1; |
729 |
dl |
1.124 |
for (int i = last, s; i >= 0; --i) { |
730 |
|
|
ForkJoinTask<?> t; |
731 |
|
|
if ((t = tasks[i]) == null) { |
732 |
|
|
ex = new NullPointerException(); |
733 |
|
|
break; |
734 |
jsr166 |
1.1 |
} |
735 |
dl |
1.124 |
if (i == 0) { |
736 |
|
|
if ((s = t.doExec()) >= 0) |
737 |
dl |
1.134 |
s = t.awaitJoin(true, false, false, 0L); |
738 |
dl |
1.124 |
if ((s & ABNORMAL) != 0) |
739 |
dl |
1.128 |
ex = t.getException(s); |
740 |
dl |
1.124 |
break; |
741 |
jsr166 |
1.1 |
} |
742 |
dl |
1.124 |
t.fork(); |
743 |
jsr166 |
1.1 |
} |
744 |
dl |
1.124 |
if (ex == null) { |
745 |
|
|
for (int i = 1, s; i <= last; ++i) { |
746 |
|
|
ForkJoinTask<?> t; |
747 |
|
|
if ((t = tasks[i]) != null) { |
748 |
|
|
if ((s = t.status) >= 0) |
749 |
dl |
1.134 |
s = t.awaitJoin(false, false, false, 0L); |
750 |
dl |
1.128 |
if ((s & ABNORMAL) != 0 && (ex = t.getException(s)) != null) |
751 |
dl |
1.124 |
break; |
752 |
|
|
} |
753 |
|
|
} |
754 |
|
|
} |
755 |
dl |
1.128 |
if (ex != null) { |
756 |
|
|
for (int i = 1, s; i <= last; ++i) |
757 |
|
|
cancelIgnoringExceptions(tasks[i]); |
758 |
dl |
1.65 |
rethrow(ex); |
759 |
dl |
1.128 |
} |
760 |
jsr166 |
1.1 |
} |
761 |
|
|
|
762 |
|
|
/** |
763 |
jsr166 |
1.7 |
* Forks all tasks in the specified collection, returning when |
764 |
jsr166 |
1.8 |
* {@code isDone} holds for each task or an (unchecked) exception |
765 |
dl |
1.20 |
* is encountered, in which case the exception is rethrown. If |
766 |
|
|
* more than one task encounters an exception, then this method |
767 |
|
|
* throws any one of these exceptions. If any task encounters an |
768 |
|
|
* exception, others may be cancelled. However, the execution |
769 |
|
|
* status of individual tasks is not guaranteed upon exceptional |
770 |
|
|
* return. The status of each task may be obtained using {@link |
771 |
|
|
* #getException()} and related methods to check if they have been |
772 |
|
|
* cancelled, completed normally or exceptionally, or left |
773 |
|
|
* unprocessed. |
774 |
jsr166 |
1.6 |
* |
775 |
jsr166 |
1.1 |
* @param tasks the collection of tasks |
776 |
jsr166 |
1.82 |
* @param <T> the type of the values returned from the tasks |
777 |
jsr166 |
1.2 |
* @return the tasks argument, to simplify usage |
778 |
jsr166 |
1.1 |
* @throws NullPointerException if tasks or any element are null |
779 |
|
|
*/ |
780 |
jsr166 |
1.2 |
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
781 |
jsr166 |
1.7 |
if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) { |
782 |
jsr166 |
1.121 |
invokeAll(tasks.toArray(new ForkJoinTask<?>[0])); |
783 |
jsr166 |
1.2 |
return tasks; |
784 |
jsr166 |
1.1 |
} |
785 |
|
|
@SuppressWarnings("unchecked") |
786 |
|
|
List<? extends ForkJoinTask<?>> ts = |
787 |
|
|
(List<? extends ForkJoinTask<?>>) tasks; |
788 |
|
|
Throwable ex = null; |
789 |
dl |
1.124 |
int last = ts.size() - 1; // nearly same as array version |
790 |
|
|
for (int i = last, s; i >= 0; --i) { |
791 |
|
|
ForkJoinTask<?> t; |
792 |
|
|
if ((t = ts.get(i)) == null) { |
793 |
|
|
ex = new NullPointerException(); |
794 |
|
|
break; |
795 |
jsr166 |
1.1 |
} |
796 |
dl |
1.124 |
if (i == 0) { |
797 |
|
|
if ((s = t.doExec()) >= 0) |
798 |
dl |
1.134 |
s = t.awaitJoin(true, false, false, 0L); |
799 |
dl |
1.124 |
if ((s & ABNORMAL) != 0) |
800 |
dl |
1.128 |
ex = t.getException(s); |
801 |
dl |
1.124 |
break; |
802 |
|
|
} |
803 |
|
|
t.fork(); |
804 |
|
|
} |
805 |
|
|
if (ex == null) { |
806 |
|
|
for (int i = 1, s; i <= last; ++i) { |
807 |
|
|
ForkJoinTask<?> t; |
808 |
|
|
if ((t = ts.get(i)) != null) { |
809 |
|
|
if ((s = t.status) >= 0) |
810 |
dl |
1.134 |
s = t.awaitJoin(false, false, false, 0L); |
811 |
dl |
1.128 |
if ((s & ABNORMAL) != 0 && (ex = t.getException(s)) != null) |
812 |
dl |
1.124 |
break; |
813 |
|
|
} |
814 |
jsr166 |
1.1 |
} |
815 |
|
|
} |
816 |
dl |
1.128 |
if (ex != null) { |
817 |
|
|
for (int i = 1, s; i <= last; ++i) |
818 |
|
|
cancelIgnoringExceptions(ts.get(i)); |
819 |
dl |
1.65 |
rethrow(ex); |
820 |
dl |
1.128 |
} |
821 |
jsr166 |
1.2 |
return tasks; |
822 |
jsr166 |
1.1 |
} |
823 |
jsr166 |
1.135 |
|
824 |
jsr166 |
1.1 |
/** |
825 |
jsr166 |
1.7 |
* Attempts to cancel execution of this task. This attempt will |
826 |
jsr166 |
1.36 |
* fail if the task has already completed or could not be |
827 |
|
|
* cancelled for some other reason. If successful, and this task |
828 |
|
|
* has not started when {@code cancel} is called, execution of |
829 |
dl |
1.38 |
* this task is suppressed. After this method returns |
830 |
|
|
* successfully, unless there is an intervening call to {@link |
831 |
|
|
* #reinitialize}, subsequent calls to {@link #isCancelled}, |
832 |
|
|
* {@link #isDone}, and {@code cancel} will return {@code true} |
833 |
|
|
* and calls to {@link #join} and related methods will result in |
834 |
|
|
* {@code CancellationException}. |
835 |
jsr166 |
1.1 |
* |
836 |
|
|
* <p>This method may be overridden in subclasses, but if so, must |
837 |
dl |
1.38 |
* still ensure that these properties hold. In particular, the |
838 |
|
|
* {@code cancel} method itself must not throw exceptions. |
839 |
jsr166 |
1.1 |
* |
840 |
jsr166 |
1.6 |
* <p>This method is designed to be invoked by <em>other</em> |
841 |
jsr166 |
1.1 |
* tasks. To terminate the current task, you can just return or |
842 |
|
|
* throw an unchecked exception from its computation method, or |
843 |
jsr166 |
1.74 |
* invoke {@link #completeExceptionally(Throwable)}. |
844 |
jsr166 |
1.1 |
* |
845 |
dl |
1.38 |
* @param mayInterruptIfRunning this value has no effect in the |
846 |
|
|
* default implementation because interrupts are not used to |
847 |
|
|
* control cancellation. |
848 |
jsr166 |
1.1 |
* |
849 |
jsr166 |
1.4 |
* @return {@code true} if this task is now cancelled |
850 |
jsr166 |
1.1 |
*/ |
851 |
|
|
public boolean cancel(boolean mayInterruptIfRunning) { |
852 |
dl |
1.124 |
return (trySetCancelled() & (ABNORMAL | THROWN)) == ABNORMAL; |
853 |
jsr166 |
1.1 |
} |
854 |
|
|
|
855 |
jsr166 |
1.8 |
public final boolean isDone() { |
856 |
|
|
return status < 0; |
857 |
|
|
} |
858 |
|
|
|
859 |
|
|
public final boolean isCancelled() { |
860 |
dl |
1.118 |
return (status & (ABNORMAL | THROWN)) == ABNORMAL; |
861 |
jsr166 |
1.8 |
} |
862 |
|
|
|
863 |
|
|
/** |
864 |
jsr166 |
1.4 |
* Returns {@code true} if this task threw an exception or was cancelled. |
865 |
jsr166 |
1.1 |
* |
866 |
jsr166 |
1.4 |
* @return {@code true} if this task threw an exception or was cancelled |
867 |
jsr166 |
1.1 |
*/ |
868 |
|
|
public final boolean isCompletedAbnormally() { |
869 |
dl |
1.118 |
return (status & ABNORMAL) != 0; |
870 |
jsr166 |
1.1 |
} |
871 |
|
|
|
872 |
|
|
/** |
873 |
jsr166 |
1.8 |
* Returns {@code true} if this task completed without throwing an |
874 |
|
|
* exception and was not cancelled. |
875 |
|
|
* |
876 |
|
|
* @return {@code true} if this task completed without throwing an |
877 |
|
|
* exception and was not cancelled |
878 |
|
|
*/ |
879 |
|
|
public final boolean isCompletedNormally() { |
880 |
dl |
1.118 |
return (status & (DONE | ABNORMAL)) == DONE; |
881 |
jsr166 |
1.8 |
} |
882 |
|
|
|
883 |
|
|
/** |
884 |
jsr166 |
1.1 |
* Returns the exception thrown by the base computation, or a |
885 |
jsr166 |
1.6 |
* {@code CancellationException} if cancelled, or {@code null} if |
886 |
|
|
* none or if the method has not yet completed. |
887 |
jsr166 |
1.1 |
* |
888 |
jsr166 |
1.4 |
* @return the exception, or {@code null} if none |
889 |
jsr166 |
1.1 |
*/ |
890 |
|
|
public final Throwable getException() { |
891 |
dl |
1.128 |
return getException(status); |
892 |
jsr166 |
1.1 |
} |
893 |
|
|
|
894 |
|
|
/** |
895 |
|
|
* Completes this task abnormally, and if not already aborted or |
896 |
|
|
* cancelled, causes it to throw the given exception upon |
897 |
|
|
* {@code join} and related operations. This method may be used |
898 |
|
|
* to induce exceptions in asynchronous tasks, or to force |
899 |
|
|
* completion of tasks that would not otherwise complete. Its use |
900 |
jsr166 |
1.6 |
* in other situations is discouraged. This method is |
901 |
jsr166 |
1.1 |
* overridable, but overridden versions must invoke {@code super} |
902 |
|
|
* implementation to maintain guarantees. |
903 |
|
|
* |
904 |
jsr166 |
1.11 |
* @param ex the exception to throw. If this exception is not a |
905 |
|
|
* {@code RuntimeException} or {@code Error}, the actual exception |
906 |
|
|
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
907 |
jsr166 |
1.1 |
*/ |
908 |
|
|
public void completeExceptionally(Throwable ex) { |
909 |
dl |
1.124 |
trySetException((ex instanceof RuntimeException) || |
910 |
|
|
(ex instanceof Error) ? ex : |
911 |
|
|
new RuntimeException(ex)); |
912 |
jsr166 |
1.1 |
} |
913 |
|
|
|
914 |
|
|
/** |
915 |
|
|
* Completes this task, and if not already aborted or cancelled, |
916 |
dl |
1.22 |
* returning the given value as the result of subsequent |
917 |
|
|
* invocations of {@code join} and related operations. This method |
918 |
|
|
* may be used to provide results for asynchronous tasks, or to |
919 |
|
|
* provide alternative handling for tasks that would not otherwise |
920 |
|
|
* complete normally. Its use in other situations is |
921 |
|
|
* discouraged. This method is overridable, but overridden |
922 |
|
|
* versions must invoke {@code super} implementation to maintain |
923 |
|
|
* guarantees. |
924 |
jsr166 |
1.1 |
* |
925 |
|
|
* @param value the result value for this task |
926 |
|
|
*/ |
927 |
|
|
public void complete(V value) { |
928 |
|
|
try { |
929 |
|
|
setRawResult(value); |
930 |
|
|
} catch (Throwable rex) { |
931 |
dl |
1.124 |
trySetException(rex); |
932 |
jsr166 |
1.1 |
return; |
933 |
|
|
} |
934 |
dl |
1.118 |
setDone(); |
935 |
jsr166 |
1.1 |
} |
936 |
|
|
|
937 |
jsr166 |
1.25 |
/** |
938 |
dl |
1.62 |
* Completes this task normally without setting a value. The most |
939 |
|
|
* recent value established by {@link #setRawResult} (or {@code |
940 |
|
|
* null} by default) will be returned as the result of subsequent |
941 |
|
|
* invocations of {@code join} and related operations. |
942 |
|
|
* |
943 |
|
|
* @since 1.8 |
944 |
dl |
1.60 |
*/ |
945 |
|
|
public final void quietlyComplete() { |
946 |
dl |
1.118 |
setDone(); |
947 |
dl |
1.60 |
} |
948 |
|
|
|
949 |
|
|
/** |
950 |
dl |
1.29 |
* Waits if necessary for the computation to complete, and then |
951 |
|
|
* retrieves its result. |
952 |
|
|
* |
953 |
|
|
* @return the computed result |
954 |
|
|
* @throws CancellationException if the computation was cancelled |
955 |
|
|
* @throws ExecutionException if the computation threw an |
956 |
|
|
* exception |
957 |
|
|
* @throws InterruptedException if the current thread is not a |
958 |
|
|
* member of a ForkJoinPool and was interrupted while waiting |
959 |
jsr166 |
1.25 |
*/ |
960 |
jsr166 |
1.1 |
public final V get() throws InterruptedException, ExecutionException { |
961 |
dl |
1.129 |
int s; |
962 |
dl |
1.134 |
if (((s = awaitJoin(false, true, false, 0L)) & ABNORMAL) != 0) |
963 |
|
|
reportExecutionException(s); |
964 |
dl |
1.129 |
return getRawResult(); |
965 |
jsr166 |
1.1 |
} |
966 |
dl |
1.14 |
|
967 |
jsr166 |
1.25 |
/** |
968 |
dl |
1.29 |
* Waits if necessary for at most the given time for the computation |
969 |
|
|
* to complete, and then retrieves its result, if available. |
970 |
|
|
* |
971 |
|
|
* @param timeout the maximum time to wait |
972 |
|
|
* @param unit the time unit of the timeout argument |
973 |
|
|
* @return the computed result |
974 |
|
|
* @throws CancellationException if the computation was cancelled |
975 |
|
|
* @throws ExecutionException if the computation threw an |
976 |
|
|
* exception |
977 |
|
|
* @throws InterruptedException if the current thread is not a |
978 |
|
|
* member of a ForkJoinPool and was interrupted while waiting |
979 |
|
|
* @throws TimeoutException if the wait timed out |
980 |
jsr166 |
1.25 |
*/ |
981 |
jsr166 |
1.1 |
public final V get(long timeout, TimeUnit unit) |
982 |
|
|
throws InterruptedException, ExecutionException, TimeoutException { |
983 |
dl |
1.129 |
int s; |
984 |
dl |
1.134 |
if ((s = awaitJoin(false, true, true, unit.toNanos(timeout))) >= 0 || |
985 |
|
|
(s & ABNORMAL) != 0) |
986 |
|
|
reportExecutionException(s); |
987 |
dl |
1.129 |
return getRawResult(); |
988 |
jsr166 |
1.1 |
} |
989 |
|
|
|
990 |
|
|
/** |
991 |
dl |
1.17 |
* Joins this task, without returning its result or throwing its |
992 |
jsr166 |
1.1 |
* exception. This method may be useful when processing |
993 |
|
|
* collections of tasks when some have been cancelled or otherwise |
994 |
|
|
* known to have aborted. |
995 |
|
|
*/ |
996 |
|
|
public final void quietlyJoin() { |
997 |
dl |
1.124 |
if (status >= 0) |
998 |
dl |
1.134 |
awaitJoin(false, false, false, 0L); |
999 |
jsr166 |
1.1 |
} |
1000 |
|
|
|
1001 |
|
|
/** |
1002 |
|
|
* Commences performing this task and awaits its completion if |
1003 |
dl |
1.17 |
* necessary, without returning its result or throwing its |
1004 |
dl |
1.22 |
* exception. |
1005 |
jsr166 |
1.1 |
*/ |
1006 |
|
|
public final void quietlyInvoke() { |
1007 |
dl |
1.124 |
if (doExec() >= 0) |
1008 |
dl |
1.134 |
awaitJoin(true, false, false, 0L); |
1009 |
jsr166 |
1.1 |
} |
1010 |
|
|
|
1011 |
|
|
/** |
1012 |
|
|
* Possibly executes tasks until the pool hosting the current task |
1013 |
jsr166 |
1.104 |
* {@linkplain ForkJoinPool#isQuiescent is quiescent}. This |
1014 |
|
|
* method may be of use in designs in which many tasks are forked, |
1015 |
|
|
* but none are explicitly joined, instead executing them until |
1016 |
|
|
* all are processed. |
1017 |
jsr166 |
1.1 |
*/ |
1018 |
|
|
public static void helpQuiesce() { |
1019 |
dl |
1.124 |
Thread t; ForkJoinWorkerThread w; ForkJoinPool p; |
1020 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread && |
1021 |
|
|
(p = (w = (ForkJoinWorkerThread)t).pool) != null) |
1022 |
dl |
1.128 |
p.helpQuiescePool(w.workQueue, Long.MAX_VALUE, false); |
1023 |
dl |
1.64 |
else |
1024 |
dl |
1.128 |
ForkJoinPool.common.externalHelpQuiescePool(Long.MAX_VALUE, false); |
1025 |
jsr166 |
1.1 |
} |
1026 |
|
|
|
1027 |
|
|
/** |
1028 |
|
|
* Resets the internal bookkeeping state of this task, allowing a |
1029 |
|
|
* subsequent {@code fork}. This method allows repeated reuse of |
1030 |
|
|
* this task, but only if reuse occurs when this task has either |
1031 |
|
|
* never been forked, or has been forked, then completed and all |
1032 |
|
|
* outstanding joins of this task have also completed. Effects |
1033 |
jsr166 |
1.6 |
* under any other usage conditions are not guaranteed. |
1034 |
|
|
* This method may be useful when executing |
1035 |
jsr166 |
1.1 |
* pre-constructed trees of subtasks in loops. |
1036 |
jsr166 |
1.34 |
* |
1037 |
dl |
1.33 |
* <p>Upon completion of this method, {@code isDone()} reports |
1038 |
|
|
* {@code false}, and {@code getException()} reports {@code |
1039 |
|
|
* null}. However, the value returned by {@code getRawResult} is |
1040 |
|
|
* unaffected. To clear this value, you can invoke {@code |
1041 |
|
|
* setRawResult(null)}. |
1042 |
jsr166 |
1.1 |
*/ |
1043 |
|
|
public void reinitialize() { |
1044 |
dl |
1.124 |
aux = null; |
1045 |
|
|
status = 0; |
1046 |
jsr166 |
1.1 |
} |
1047 |
|
|
|
1048 |
|
|
/** |
1049 |
jsr166 |
1.103 |
* Returns the pool hosting the current thread, or {@code null} |
1050 |
|
|
* if the current thread is executing outside of any ForkJoinPool. |
1051 |
|
|
* |
1052 |
|
|
* <p>This method returns {@code null} if and only if {@link |
1053 |
|
|
* #inForkJoinPool} returns {@code false}. |
1054 |
jsr166 |
1.1 |
* |
1055 |
jsr166 |
1.97 |
* @return the pool, or {@code null} if none |
1056 |
jsr166 |
1.1 |
*/ |
1057 |
|
|
public static ForkJoinPool getPool() { |
1058 |
dl |
1.124 |
Thread t; |
1059 |
|
|
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1060 |
|
|
((ForkJoinWorkerThread) t).pool : null); |
1061 |
jsr166 |
1.1 |
} |
1062 |
|
|
|
1063 |
|
|
/** |
1064 |
dl |
1.42 |
* Returns {@code true} if the current thread is a {@link |
1065 |
|
|
* ForkJoinWorkerThread} executing as a ForkJoinPool computation. |
1066 |
jsr166 |
1.1 |
* |
1067 |
dl |
1.42 |
* @return {@code true} if the current thread is a {@link |
1068 |
|
|
* ForkJoinWorkerThread} executing as a ForkJoinPool computation, |
1069 |
|
|
* or {@code false} otherwise |
1070 |
jsr166 |
1.1 |
*/ |
1071 |
|
|
public static boolean inForkJoinPool() { |
1072 |
|
|
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
1073 |
|
|
} |
1074 |
|
|
|
1075 |
|
|
/** |
1076 |
|
|
* Tries to unschedule this task for execution. This method will |
1077 |
dl |
1.64 |
* typically (but is not guaranteed to) succeed if this task is |
1078 |
|
|
* the most recently forked task by the current thread, and has |
1079 |
|
|
* not commenced executing in another thread. This method may be |
1080 |
|
|
* useful when arranging alternative local processing of tasks |
1081 |
|
|
* that could have been, but were not, stolen. |
1082 |
jsr166 |
1.1 |
* |
1083 |
jsr166 |
1.4 |
* @return {@code true} if unforked |
1084 |
jsr166 |
1.1 |
*/ |
1085 |
|
|
public boolean tryUnfork() { |
1086 |
dl |
1.134 |
Thread t; ForkJoinPool.WorkQueue q; |
1087 |
jsr166 |
1.136 |
return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
1088 |
|
|
? (q = ((ForkJoinWorkerThread)t).workQueue) != null |
1089 |
|
|
&& q.tryUnpush(this) |
1090 |
|
|
: (q = ForkJoinPool.commonQueue()) != null |
1091 |
|
|
&& q.externalTryUnpush(this); |
1092 |
jsr166 |
1.1 |
} |
1093 |
|
|
|
1094 |
|
|
/** |
1095 |
|
|
* Returns an estimate of the number of tasks that have been |
1096 |
|
|
* forked by the current worker thread but not yet executed. This |
1097 |
|
|
* value may be useful for heuristic decisions about whether to |
1098 |
|
|
* fork other tasks. |
1099 |
|
|
* |
1100 |
|
|
* @return the number of tasks |
1101 |
|
|
*/ |
1102 |
|
|
public static int getQueuedTaskCount() { |
1103 |
dl |
1.66 |
Thread t; ForkJoinPool.WorkQueue q; |
1104 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
1105 |
|
|
q = ((ForkJoinWorkerThread)t).workQueue; |
1106 |
|
|
else |
1107 |
dl |
1.124 |
q = ForkJoinPool.commonQueue(); |
1108 |
dl |
1.66 |
return (q == null) ? 0 : q.queueSize(); |
1109 |
jsr166 |
1.1 |
} |
1110 |
|
|
|
1111 |
|
|
/** |
1112 |
|
|
* Returns an estimate of how many more locally queued tasks are |
1113 |
|
|
* held by the current worker thread than there are other worker |
1114 |
dl |
1.64 |
* threads that might steal them, or zero if this thread is not |
1115 |
|
|
* operating in a ForkJoinPool. This value may be useful for |
1116 |
jsr166 |
1.1 |
* heuristic decisions about whether to fork other tasks. In many |
1117 |
|
|
* usages of ForkJoinTasks, at steady state, each worker should |
1118 |
|
|
* aim to maintain a small constant surplus (for example, 3) of |
1119 |
|
|
* tasks, and to process computations locally if this threshold is |
1120 |
|
|
* exceeded. |
1121 |
|
|
* |
1122 |
|
|
* @return the surplus number of tasks, which may be negative |
1123 |
|
|
*/ |
1124 |
|
|
public static int getSurplusQueuedTaskCount() { |
1125 |
dl |
1.66 |
return ForkJoinPool.getSurplusQueuedTaskCount(); |
1126 |
jsr166 |
1.1 |
} |
1127 |
|
|
|
1128 |
|
|
// Extension methods |
1129 |
|
|
|
1130 |
|
|
/** |
1131 |
jsr166 |
1.4 |
* Returns the result that would be returned by {@link #join}, even |
1132 |
|
|
* if this task completed abnormally, or {@code null} if this task |
1133 |
|
|
* is not known to have been completed. This method is designed |
1134 |
|
|
* to aid debugging, as well as to support extensions. Its use in |
1135 |
|
|
* any other context is discouraged. |
1136 |
jsr166 |
1.1 |
* |
1137 |
jsr166 |
1.4 |
* @return the result, or {@code null} if not completed |
1138 |
jsr166 |
1.1 |
*/ |
1139 |
|
|
public abstract V getRawResult(); |
1140 |
|
|
|
1141 |
|
|
/** |
1142 |
|
|
* Forces the given value to be returned as a result. This method |
1143 |
|
|
* is designed to support extensions, and should not in general be |
1144 |
|
|
* called otherwise. |
1145 |
|
|
* |
1146 |
|
|
* @param value the value |
1147 |
|
|
*/ |
1148 |
|
|
protected abstract void setRawResult(V value); |
1149 |
|
|
|
1150 |
|
|
/** |
1151 |
dl |
1.62 |
* Immediately performs the base action of this task and returns |
1152 |
|
|
* true if, upon return from this method, this task is guaranteed |
1153 |
dl |
1.122 |
* to have completed. This method may return false otherwise, to |
1154 |
|
|
* indicate that this task is not necessarily complete (or is not |
1155 |
|
|
* known to be complete), for example in asynchronous actions that |
1156 |
|
|
* require explicit invocations of completion methods. This method |
1157 |
|
|
* may also throw an (unchecked) exception to indicate abnormal |
1158 |
|
|
* exit. This method is designed to support extensions, and should |
1159 |
|
|
* not in general be called otherwise. |
1160 |
jsr166 |
1.1 |
* |
1161 |
dl |
1.62 |
* @return {@code true} if this task is known to have completed normally |
1162 |
jsr166 |
1.1 |
*/ |
1163 |
|
|
protected abstract boolean exec(); |
1164 |
|
|
|
1165 |
|
|
/** |
1166 |
jsr166 |
1.5 |
* Returns, but does not unschedule or execute, a task queued by |
1167 |
|
|
* the current thread but not yet executed, if one is immediately |
1168 |
dl |
1.66 |
* available. There is no guarantee that this task will actually |
1169 |
|
|
* be polled or executed next. Conversely, this method may return |
1170 |
|
|
* null even if a task exists but cannot be accessed without |
1171 |
|
|
* contention with other threads. This method is designed |
1172 |
jsr166 |
1.5 |
* primarily to support extensions, and is unlikely to be useful |
1173 |
jsr166 |
1.6 |
* otherwise. |
1174 |
|
|
* |
1175 |
jsr166 |
1.4 |
* @return the next task, or {@code null} if none are available |
1176 |
jsr166 |
1.1 |
*/ |
1177 |
|
|
protected static ForkJoinTask<?> peekNextLocalTask() { |
1178 |
dl |
1.66 |
Thread t; ForkJoinPool.WorkQueue q; |
1179 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
1180 |
|
|
q = ((ForkJoinWorkerThread)t).workQueue; |
1181 |
|
|
else |
1182 |
dl |
1.124 |
q = ForkJoinPool.commonQueue(); |
1183 |
dl |
1.66 |
return (q == null) ? null : q.peek(); |
1184 |
jsr166 |
1.1 |
} |
1185 |
|
|
|
1186 |
|
|
/** |
1187 |
|
|
* Unschedules and returns, without executing, the next task |
1188 |
dl |
1.64 |
* queued by the current thread but not yet executed, if the |
1189 |
|
|
* current thread is operating in a ForkJoinPool. This method is |
1190 |
|
|
* designed primarily to support extensions, and is unlikely to be |
1191 |
|
|
* useful otherwise. |
1192 |
jsr166 |
1.1 |
* |
1193 |
jsr166 |
1.4 |
* @return the next task, or {@code null} if none are available |
1194 |
jsr166 |
1.1 |
*/ |
1195 |
|
|
protected static ForkJoinTask<?> pollNextLocalTask() { |
1196 |
dl |
1.64 |
Thread t; |
1197 |
dl |
1.124 |
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1198 |
|
|
((ForkJoinWorkerThread)t).workQueue.nextLocalTask() : null); |
1199 |
jsr166 |
1.1 |
} |
1200 |
|
|
|
1201 |
|
|
/** |
1202 |
dl |
1.64 |
* If the current thread is operating in a ForkJoinPool, |
1203 |
|
|
* unschedules and returns, without executing, the next task |
1204 |
jsr166 |
1.1 |
* queued by the current thread but not yet executed, if one is |
1205 |
|
|
* available, or if not available, a task that was forked by some |
1206 |
|
|
* other thread, if available. Availability may be transient, so a |
1207 |
dl |
1.64 |
* {@code null} result does not necessarily imply quiescence of |
1208 |
|
|
* the pool this task is operating in. This method is designed |
1209 |
jsr166 |
1.1 |
* primarily to support extensions, and is unlikely to be useful |
1210 |
jsr166 |
1.6 |
* otherwise. |
1211 |
|
|
* |
1212 |
jsr166 |
1.4 |
* @return a task, or {@code null} if none are available |
1213 |
jsr166 |
1.1 |
*/ |
1214 |
|
|
protected static ForkJoinTask<?> pollTask() { |
1215 |
dl |
1.124 |
Thread t; ForkJoinWorkerThread w; |
1216 |
|
|
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1217 |
|
|
(w = (ForkJoinWorkerThread)t).pool.nextTaskFor(w.workQueue) : |
1218 |
|
|
null); |
1219 |
dl |
1.54 |
} |
1220 |
|
|
|
1221 |
dl |
1.94 |
/** |
1222 |
|
|
* If the current thread is operating in a ForkJoinPool, |
1223 |
|
|
* unschedules and returns, without executing, a task externally |
1224 |
|
|
* submitted to the pool, if one is available. Availability may be |
1225 |
|
|
* transient, so a {@code null} result does not necessarily imply |
1226 |
|
|
* quiescence of the pool. This method is designed primarily to |
1227 |
|
|
* support extensions, and is unlikely to be useful otherwise. |
1228 |
|
|
* |
1229 |
|
|
* @return a task, or {@code null} if none are available |
1230 |
jsr166 |
1.107 |
* @since 9 |
1231 |
dl |
1.94 |
*/ |
1232 |
|
|
protected static ForkJoinTask<?> pollSubmission() { |
1233 |
dl |
1.96 |
Thread t; |
1234 |
dl |
1.124 |
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1235 |
|
|
((ForkJoinWorkerThread)t).pool.pollSubmission() : null); |
1236 |
dl |
1.94 |
} |
1237 |
|
|
|
1238 |
dl |
1.60 |
// tag operations |
1239 |
dl |
1.54 |
|
1240 |
|
|
/** |
1241 |
dl |
1.60 |
* Returns the tag for this task. |
1242 |
dl |
1.54 |
* |
1243 |
dl |
1.60 |
* @return the tag for this task |
1244 |
dl |
1.54 |
* @since 1.8 |
1245 |
|
|
*/ |
1246 |
dl |
1.60 |
public final short getForkJoinTaskTag() { |
1247 |
|
|
return (short)status; |
1248 |
dl |
1.54 |
} |
1249 |
|
|
|
1250 |
|
|
/** |
1251 |
jsr166 |
1.102 |
* Atomically sets the tag value for this task and returns the old value. |
1252 |
dl |
1.54 |
* |
1253 |
jsr166 |
1.102 |
* @param newValue the new tag value |
1254 |
dl |
1.60 |
* @return the previous value of the tag |
1255 |
dl |
1.54 |
* @since 1.8 |
1256 |
|
|
*/ |
1257 |
jsr166 |
1.102 |
public final short setForkJoinTaskTag(short newValue) { |
1258 |
dl |
1.54 |
for (int s;;) { |
1259 |
dl |
1.124 |
if (casStatus(s = status, (s & ~SMASK) | (newValue & SMASK))) |
1260 |
dl |
1.60 |
return (short)s; |
1261 |
dl |
1.54 |
} |
1262 |
|
|
} |
1263 |
|
|
|
1264 |
|
|
/** |
1265 |
dl |
1.60 |
* Atomically conditionally sets the tag value for this task. |
1266 |
|
|
* Among other applications, tags can be used as visit markers |
1267 |
dl |
1.61 |
* in tasks operating on graphs, as in methods that check: {@code |
1268 |
dl |
1.60 |
* if (task.compareAndSetForkJoinTaskTag((short)0, (short)1))} |
1269 |
|
|
* before processing, otherwise exiting because the node has |
1270 |
|
|
* already been visited. |
1271 |
dl |
1.54 |
* |
1272 |
jsr166 |
1.102 |
* @param expect the expected tag value |
1273 |
|
|
* @param update the new tag value |
1274 |
jsr166 |
1.76 |
* @return {@code true} if successful; i.e., the current value was |
1275 |
jsr166 |
1.102 |
* equal to {@code expect} and was changed to {@code update}. |
1276 |
dl |
1.54 |
* @since 1.8 |
1277 |
|
|
*/ |
1278 |
jsr166 |
1.102 |
public final boolean compareAndSetForkJoinTaskTag(short expect, short update) { |
1279 |
dl |
1.54 |
for (int s;;) { |
1280 |
jsr166 |
1.102 |
if ((short)(s = status) != expect) |
1281 |
dl |
1.54 |
return false; |
1282 |
dl |
1.124 |
if (casStatus(s, (s & ~SMASK) | (update & SMASK))) |
1283 |
dl |
1.54 |
return true; |
1284 |
|
|
} |
1285 |
jsr166 |
1.1 |
} |
1286 |
|
|
|
1287 |
jsr166 |
1.5 |
/** |
1288 |
jsr166 |
1.95 |
* Adapter for Runnables. This implements RunnableFuture |
1289 |
jsr166 |
1.5 |
* to be compliant with AbstractExecutorService constraints |
1290 |
|
|
* when used in ForkJoinPool. |
1291 |
|
|
*/ |
1292 |
|
|
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
1293 |
|
|
implements RunnableFuture<T> { |
1294 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1295 |
jsr166 |
1.5 |
final Runnable runnable; |
1296 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1297 |
jsr166 |
1.5 |
T result; |
1298 |
|
|
AdaptedRunnable(Runnable runnable, T result) { |
1299 |
|
|
if (runnable == null) throw new NullPointerException(); |
1300 |
|
|
this.runnable = runnable; |
1301 |
dl |
1.59 |
this.result = result; // OK to set this even before completion |
1302 |
jsr166 |
1.5 |
} |
1303 |
dl |
1.59 |
public final T getRawResult() { return result; } |
1304 |
|
|
public final void setRawResult(T v) { result = v; } |
1305 |
|
|
public final boolean exec() { runnable.run(); return true; } |
1306 |
|
|
public final void run() { invoke(); } |
1307 |
jsr166 |
1.116 |
public String toString() { |
1308 |
|
|
return super.toString() + "[Wrapped task = " + runnable + "]"; |
1309 |
|
|
} |
1310 |
dl |
1.59 |
private static final long serialVersionUID = 5232453952276885070L; |
1311 |
|
|
} |
1312 |
|
|
|
1313 |
|
|
/** |
1314 |
jsr166 |
1.99 |
* Adapter for Runnables without results. |
1315 |
dl |
1.59 |
*/ |
1316 |
|
|
static final class AdaptedRunnableAction extends ForkJoinTask<Void> |
1317 |
|
|
implements RunnableFuture<Void> { |
1318 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1319 |
dl |
1.59 |
final Runnable runnable; |
1320 |
|
|
AdaptedRunnableAction(Runnable runnable) { |
1321 |
|
|
if (runnable == null) throw new NullPointerException(); |
1322 |
|
|
this.runnable = runnable; |
1323 |
jsr166 |
1.5 |
} |
1324 |
dl |
1.59 |
public final Void getRawResult() { return null; } |
1325 |
|
|
public final void setRawResult(Void v) { } |
1326 |
|
|
public final boolean exec() { runnable.run(); return true; } |
1327 |
|
|
public final void run() { invoke(); } |
1328 |
jsr166 |
1.116 |
public String toString() { |
1329 |
|
|
return super.toString() + "[Wrapped task = " + runnable + "]"; |
1330 |
|
|
} |
1331 |
jsr166 |
1.5 |
private static final long serialVersionUID = 5232453952276885070L; |
1332 |
|
|
} |
1333 |
|
|
|
1334 |
|
|
/** |
1335 |
jsr166 |
1.99 |
* Adapter for Runnables in which failure forces worker exception. |
1336 |
dl |
1.73 |
*/ |
1337 |
|
|
static final class RunnableExecuteAction extends ForkJoinTask<Void> { |
1338 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1339 |
dl |
1.73 |
final Runnable runnable; |
1340 |
|
|
RunnableExecuteAction(Runnable runnable) { |
1341 |
|
|
if (runnable == null) throw new NullPointerException(); |
1342 |
|
|
this.runnable = runnable; |
1343 |
|
|
} |
1344 |
|
|
public final Void getRawResult() { return null; } |
1345 |
|
|
public final void setRawResult(Void v) { } |
1346 |
|
|
public final boolean exec() { runnable.run(); return true; } |
1347 |
dl |
1.124 |
int trySetException(Throwable ex) { |
1348 |
dl |
1.126 |
int s; // if runnable has a handler, invoke it |
1349 |
|
|
if (isExceptionalStatus(s = trySetThrown(ex)) && |
1350 |
|
|
runnable instanceof java.lang.Thread.UncaughtExceptionHandler) { |
1351 |
|
|
try { |
1352 |
|
|
((java.lang.Thread.UncaughtExceptionHandler)runnable). |
1353 |
|
|
uncaughtException(Thread.currentThread(), ex); |
1354 |
|
|
} catch (Throwable ignore) { |
1355 |
|
|
} |
1356 |
|
|
} |
1357 |
dl |
1.124 |
return s; |
1358 |
dl |
1.73 |
} |
1359 |
|
|
private static final long serialVersionUID = 5232453952276885070L; |
1360 |
|
|
} |
1361 |
|
|
|
1362 |
|
|
/** |
1363 |
jsr166 |
1.99 |
* Adapter for Callables. |
1364 |
jsr166 |
1.5 |
*/ |
1365 |
|
|
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
1366 |
|
|
implements RunnableFuture<T> { |
1367 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1368 |
jsr166 |
1.6 |
final Callable<? extends T> callable; |
1369 |
jsr166 |
1.123 |
@SuppressWarnings("serial") // Conditionally serializable |
1370 |
jsr166 |
1.5 |
T result; |
1371 |
jsr166 |
1.6 |
AdaptedCallable(Callable<? extends T> callable) { |
1372 |
jsr166 |
1.5 |
if (callable == null) throw new NullPointerException(); |
1373 |
|
|
this.callable = callable; |
1374 |
|
|
} |
1375 |
dl |
1.59 |
public final T getRawResult() { return result; } |
1376 |
|
|
public final void setRawResult(T v) { result = v; } |
1377 |
|
|
public final boolean exec() { |
1378 |
jsr166 |
1.5 |
try { |
1379 |
|
|
result = callable.call(); |
1380 |
|
|
return true; |
1381 |
|
|
} catch (RuntimeException rex) { |
1382 |
|
|
throw rex; |
1383 |
|
|
} catch (Exception ex) { |
1384 |
|
|
throw new RuntimeException(ex); |
1385 |
|
|
} |
1386 |
|
|
} |
1387 |
dl |
1.59 |
public final void run() { invoke(); } |
1388 |
jsr166 |
1.116 |
public String toString() { |
1389 |
|
|
return super.toString() + "[Wrapped task = " + callable + "]"; |
1390 |
|
|
} |
1391 |
jsr166 |
1.117 |
private static final long serialVersionUID = 2838392045355241008L; |
1392 |
jsr166 |
1.5 |
} |
1393 |
jsr166 |
1.2 |
|
1394 |
dl |
1.129 |
static final class AdaptedInterruptibleCallable<T> extends ForkJoinTask<T> |
1395 |
|
|
implements RunnableFuture<T> { |
1396 |
|
|
@SuppressWarnings("serial") // Conditionally serializable |
1397 |
|
|
final Callable<? extends T> callable; |
1398 |
|
|
@SuppressWarnings("serial") // Conditionally serializable |
1399 |
|
|
transient volatile Thread runner; |
1400 |
|
|
T result; |
1401 |
|
|
AdaptedInterruptibleCallable(Callable<? extends T> callable) { |
1402 |
|
|
if (callable == null) throw new NullPointerException(); |
1403 |
|
|
this.callable = callable; |
1404 |
|
|
} |
1405 |
|
|
public final T getRawResult() { return result; } |
1406 |
|
|
public final void setRawResult(T v) { result = v; } |
1407 |
|
|
public final boolean exec() { |
1408 |
|
|
Thread.interrupted(); |
1409 |
|
|
runner = Thread.currentThread(); |
1410 |
|
|
try { |
1411 |
dl |
1.133 |
if (!isDone()) // recheck |
1412 |
|
|
result = callable.call(); |
1413 |
dl |
1.129 |
return true; |
1414 |
|
|
} catch (RuntimeException rex) { |
1415 |
|
|
throw rex; |
1416 |
|
|
} catch (Exception ex) { |
1417 |
|
|
throw new RuntimeException(ex); |
1418 |
|
|
} finally { |
1419 |
|
|
runner = null; |
1420 |
|
|
Thread.interrupted(); |
1421 |
|
|
} |
1422 |
|
|
} |
1423 |
|
|
public final void run() { invoke(); } |
1424 |
|
|
public final boolean cancel(boolean mayInterruptIfRunning) { |
1425 |
|
|
Thread t; |
1426 |
|
|
boolean stat = super.cancel(false); |
1427 |
|
|
if (mayInterruptIfRunning && (t = runner) != null) { |
1428 |
|
|
try { |
1429 |
|
|
t.interrupt(); |
1430 |
|
|
} catch (Throwable ignore) { |
1431 |
|
|
} |
1432 |
|
|
} |
1433 |
|
|
return stat; |
1434 |
|
|
} |
1435 |
|
|
public String toString() { |
1436 |
|
|
return super.toString() + "[Wrapped task = " + callable + "]"; |
1437 |
|
|
} |
1438 |
|
|
private static final long serialVersionUID = 2838392045355241008L; |
1439 |
|
|
} |
1440 |
|
|
|
1441 |
jsr166 |
1.2 |
/** |
1442 |
jsr166 |
1.6 |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1443 |
|
|
* method of the given {@code Runnable} as its action, and returns |
1444 |
|
|
* a null result upon {@link #join}. |
1445 |
jsr166 |
1.2 |
* |
1446 |
|
|
* @param runnable the runnable action |
1447 |
|
|
* @return the task |
1448 |
|
|
*/ |
1449 |
jsr166 |
1.6 |
public static ForkJoinTask<?> adapt(Runnable runnable) { |
1450 |
dl |
1.59 |
return new AdaptedRunnableAction(runnable); |
1451 |
jsr166 |
1.2 |
} |
1452 |
|
|
|
1453 |
|
|
/** |
1454 |
jsr166 |
1.6 |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1455 |
|
|
* method of the given {@code Runnable} as its action, and returns |
1456 |
|
|
* the given result upon {@link #join}. |
1457 |
jsr166 |
1.2 |
* |
1458 |
|
|
* @param runnable the runnable action |
1459 |
|
|
* @param result the result upon completion |
1460 |
jsr166 |
1.82 |
* @param <T> the type of the result |
1461 |
jsr166 |
1.2 |
* @return the task |
1462 |
|
|
*/ |
1463 |
|
|
public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) { |
1464 |
jsr166 |
1.5 |
return new AdaptedRunnable<T>(runnable, result); |
1465 |
jsr166 |
1.2 |
} |
1466 |
|
|
|
1467 |
|
|
/** |
1468 |
jsr166 |
1.6 |
* Returns a new {@code ForkJoinTask} that performs the {@code call} |
1469 |
|
|
* method of the given {@code Callable} as its action, and returns |
1470 |
|
|
* its result upon {@link #join}, translating any checked exceptions |
1471 |
|
|
* encountered into {@code RuntimeException}. |
1472 |
jsr166 |
1.2 |
* |
1473 |
|
|
* @param callable the callable action |
1474 |
jsr166 |
1.82 |
* @param <T> the type of the callable's result |
1475 |
jsr166 |
1.2 |
* @return the task |
1476 |
|
|
*/ |
1477 |
jsr166 |
1.6 |
public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) { |
1478 |
jsr166 |
1.5 |
return new AdaptedCallable<T>(callable); |
1479 |
jsr166 |
1.2 |
} |
1480 |
|
|
|
1481 |
dl |
1.129 |
/** |
1482 |
jsr166 |
1.138 |
* Returns a new {@code ForkJoinTask} that performs the {@code call} |
1483 |
|
|
* method of the given {@code Callable} as its action, and returns |
1484 |
|
|
* its result upon {@link #join}, translating any checked exceptions |
1485 |
|
|
* encountered into {@code RuntimeException}. Additionally, |
1486 |
|
|
* invocations of {@code cancel} with {@code mayInterruptIfRunning |
1487 |
|
|
* true} will attempt to interrupt the thread performing the task. |
1488 |
dl |
1.129 |
* |
1489 |
|
|
* @param callable the callable action |
1490 |
|
|
* @param <T> the type of the callable's result |
1491 |
|
|
* @return the task |
1492 |
|
|
* |
1493 |
jsr166 |
1.137 |
* @since 15 |
1494 |
dl |
1.129 |
*/ |
1495 |
|
|
public static <T> ForkJoinTask<T> adaptInterruptible(Callable<? extends T> callable) { |
1496 |
|
|
return new AdaptedInterruptibleCallable<T>(callable); |
1497 |
|
|
} |
1498 |
|
|
|
1499 |
jsr166 |
1.1 |
// Serialization support |
1500 |
|
|
|
1501 |
|
|
private static final long serialVersionUID = -7721805057305804111L; |
1502 |
|
|
|
1503 |
|
|
/** |
1504 |
jsr166 |
1.53 |
* Saves this task to a stream (that is, serializes it). |
1505 |
jsr166 |
1.1 |
* |
1506 |
jsr166 |
1.83 |
* @param s the stream |
1507 |
jsr166 |
1.84 |
* @throws java.io.IOException if an I/O error occurs |
1508 |
jsr166 |
1.1 |
* @serialData the current run status and the exception thrown |
1509 |
jsr166 |
1.4 |
* during execution, or {@code null} if none |
1510 |
jsr166 |
1.1 |
*/ |
1511 |
|
|
private void writeObject(java.io.ObjectOutputStream s) |
1512 |
|
|
throws java.io.IOException { |
1513 |
dl |
1.124 |
Aux a; |
1514 |
jsr166 |
1.1 |
s.defaultWriteObject(); |
1515 |
dl |
1.124 |
s.writeObject((a = aux) == null ? null : a.ex); |
1516 |
jsr166 |
1.1 |
} |
1517 |
|
|
|
1518 |
|
|
/** |
1519 |
jsr166 |
1.53 |
* Reconstitutes this task from a stream (that is, deserializes it). |
1520 |
jsr166 |
1.83 |
* @param s the stream |
1521 |
jsr166 |
1.84 |
* @throws ClassNotFoundException if the class of a serialized object |
1522 |
|
|
* could not be found |
1523 |
|
|
* @throws java.io.IOException if an I/O error occurs |
1524 |
jsr166 |
1.1 |
*/ |
1525 |
|
|
private void readObject(java.io.ObjectInputStream s) |
1526 |
|
|
throws java.io.IOException, ClassNotFoundException { |
1527 |
|
|
s.defaultReadObject(); |
1528 |
|
|
Object ex = s.readObject(); |
1529 |
|
|
if (ex != null) |
1530 |
dl |
1.124 |
trySetThrown((Throwable)ex); |
1531 |
jsr166 |
1.1 |
} |
1532 |
|
|
|
1533 |
dl |
1.45 |
static { |
1534 |
jsr166 |
1.1 |
try { |
1535 |
dl |
1.109 |
MethodHandles.Lookup l = MethodHandles.lookup(); |
1536 |
|
|
STATUS = l.findVarHandle(ForkJoinTask.class, "status", int.class); |
1537 |
dl |
1.124 |
AUX = l.findVarHandle(ForkJoinTask.class, "aux", Aux.class); |
1538 |
jsr166 |
1.91 |
} catch (ReflectiveOperationException e) { |
1539 |
jsr166 |
1.120 |
throw new ExceptionInInitializerError(e); |
1540 |
jsr166 |
1.1 |
} |
1541 |
|
|
} |
1542 |
dl |
1.45 |
|
1543 |
jsr166 |
1.1 |
} |