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dl |
1.1 |
/* |
2 |
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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 |
1.77 |
* http://creativecommons.org/publicdomain/zero/1.0/ |
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dl |
1.1 |
*/ |
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package jsr166y; |
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jsr166 |
1.17 |
|
9 |
dl |
1.1 |
import java.io.Serializable; |
10 |
jsr166 |
1.17 |
import java.util.Collection; |
11 |
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import java.util.List; |
12 |
dl |
1.32 |
import java.util.RandomAccess; |
13 |
dl |
1.74 |
import java.lang.ref.WeakReference; |
14 |
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import java.lang.ref.ReferenceQueue; |
15 |
dl |
1.66 |
import java.util.concurrent.Callable; |
16 |
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import java.util.concurrent.CancellationException; |
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import java.util.concurrent.ExecutionException; |
18 |
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import java.util.concurrent.Future; |
19 |
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import java.util.concurrent.RejectedExecutionException; |
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import java.util.concurrent.RunnableFuture; |
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import java.util.concurrent.TimeUnit; |
22 |
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import java.util.concurrent.TimeoutException; |
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dl |
1.74 |
import java.util.concurrent.locks.ReentrantLock; |
24 |
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import java.lang.reflect.Constructor; |
25 |
dl |
1.1 |
|
26 |
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/** |
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jsr166 |
1.26 |
* Abstract base class for tasks that run within a {@link ForkJoinPool}. |
28 |
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* A {@code ForkJoinTask} is a thread-like entity that is much |
29 |
dl |
1.2 |
* lighter weight than a normal thread. Huge numbers of tasks and |
30 |
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* subtasks may be hosted by a small number of actual threads in a |
31 |
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* ForkJoinPool, at the price of some usage limitations. |
32 |
dl |
1.4 |
* |
33 |
jsr166 |
1.28 |
* <p>A "main" {@code ForkJoinTask} begins execution when submitted |
34 |
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* to a {@link ForkJoinPool}. Once started, it will usually in turn |
35 |
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* start other subtasks. As indicated by the name of this class, |
36 |
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* many programs using {@code ForkJoinTask} employ only methods |
37 |
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* {@link #fork} and {@link #join}, or derivatives such as {@link |
38 |
dl |
1.62 |
* #invokeAll(ForkJoinTask...) invokeAll}. However, this class also |
39 |
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* provides a number of other methods that can come into play in |
40 |
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* advanced usages, as well as extension mechanics that allow |
41 |
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* support of new forms of fork/join processing. |
42 |
dl |
1.4 |
* |
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jsr166 |
1.28 |
* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}. |
44 |
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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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* reflecting their intended use as computational tasks calculating |
47 |
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* pure functions or operating on purely isolated objects. The |
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* primary coordination mechanisms are {@link #fork}, that arranges |
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* asynchronous execution, and {@link #join}, that doesn't proceed |
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* until the task's result has been computed. Computations should |
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* avoid {@code synchronized} methods or blocks, and should minimize |
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* other blocking synchronization apart from joining other tasks or |
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* using synchronizers such as Phasers that are advertised to |
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* cooperate with fork/join scheduling. Tasks should also not perform |
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* blocking IO, and should ideally access variables that are |
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* completely independent of those accessed by other running |
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* tasks. Minor breaches of these restrictions, for example using |
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* shared output streams, may be tolerable in practice, but frequent |
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* use may result in poor performance, and the potential to |
60 |
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* indefinitely stall if the number of threads not waiting for IO or |
61 |
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* other external synchronization becomes exhausted. This usage |
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* restriction is in part enforced by not permitting checked |
63 |
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* exceptions such as {@code IOExceptions} to be thrown. However, |
64 |
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* computations may still encounter unchecked exceptions, that are |
65 |
dl |
1.32 |
* rethrown to callers attempting to join them. These exceptions may |
66 |
jsr166 |
1.44 |
* additionally include {@link RejectedExecutionException} stemming |
67 |
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* from internal resource exhaustion, such as failure to allocate |
68 |
dl |
1.74 |
* internal task queues. Rethrown exceptions behave in the same way as |
69 |
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* regular exceptions, but, when possible, contain stack traces (as |
70 |
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* displayed for example using {@code ex.printStackTrace()}) of both |
71 |
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* the thread that initiated the computation as well as the thread |
72 |
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* actually encountering the exception; minimally only the latter. |
73 |
dl |
1.1 |
* |
74 |
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1.2 |
* <p>The primary method for awaiting completion and extracting |
75 |
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* results of a task is {@link #join}, but there are several variants: |
76 |
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* The {@link Future#get} methods support interruptible and/or timed |
77 |
jsr166 |
1.8 |
* waits for completion and report results using {@code Future} |
78 |
dl |
1.49 |
* conventions. Method {@link #invoke} is semantically |
79 |
dl |
1.35 |
* equivalent to {@code fork(); join()} but always attempts to begin |
80 |
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* execution in the current thread. The "<em>quiet</em>" forms of |
81 |
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* these methods do not extract results or report exceptions. These |
82 |
dl |
1.2 |
* may be useful when a set of tasks are being executed, and you need |
83 |
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* to delay processing of results or exceptions until all complete. |
84 |
jsr166 |
1.8 |
* Method {@code invokeAll} (available in multiple versions) |
85 |
dl |
1.2 |
* performs the most common form of parallel invocation: forking a set |
86 |
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* of tasks and joining them all. |
87 |
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* |
88 |
dl |
1.35 |
* <p>The execution status of tasks may be queried at several levels |
89 |
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* of detail: {@link #isDone} is true if a task completed in any way |
90 |
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* (including the case where a task was cancelled without executing); |
91 |
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* {@link #isCompletedNormally} is true if a task completed without |
92 |
dl |
1.42 |
* cancellation or encountering an exception; {@link #isCancelled} is |
93 |
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* true if the task was cancelled (in which case {@link #getException} |
94 |
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* returns a {@link java.util.concurrent.CancellationException}); and |
95 |
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* {@link #isCompletedAbnormally} is true if a task was either |
96 |
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* cancelled or encountered an exception, in which case {@link |
97 |
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* #getException} will return either the encountered exception or |
98 |
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* {@link java.util.concurrent.CancellationException}. |
99 |
dl |
1.35 |
* |
100 |
jsr166 |
1.28 |
* <p>The ForkJoinTask class is not usually directly subclassed. |
101 |
dl |
1.2 |
* Instead, you subclass one of the abstract classes that support a |
102 |
dl |
1.27 |
* particular style of fork/join processing, typically {@link |
103 |
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* RecursiveAction} for computations that do not return results, or |
104 |
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* {@link RecursiveTask} for those that do. Normally, a concrete |
105 |
dl |
1.2 |
* ForkJoinTask subclass declares fields comprising its parameters, |
106 |
jsr166 |
1.8 |
* established in a constructor, and then defines a {@code compute} |
107 |
dl |
1.2 |
* method that somehow uses the control methods supplied by this base |
108 |
jsr166 |
1.8 |
* class. While these methods have {@code public} access (to allow |
109 |
dl |
1.32 |
* instances of different task subclasses to call each other's |
110 |
dl |
1.2 |
* methods), some of them may only be called from within other |
111 |
dl |
1.13 |
* ForkJoinTasks (as may be determined using method {@link |
112 |
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* #inForkJoinPool}). Attempts to invoke them in other contexts |
113 |
jsr166 |
1.14 |
* result in exceptions or errors, possibly including |
114 |
dl |
1.57 |
* {@code ClassCastException}. |
115 |
dl |
1.1 |
* |
116 |
dl |
1.69 |
* <p>Method {@link #join} and its variants are appropriate for use |
117 |
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* only when completion dependencies are acyclic; that is, the |
118 |
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* parallel computation can be described as a directed acyclic graph |
119 |
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* (DAG). Otherwise, executions may encounter a form of deadlock as |
120 |
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* tasks cyclically wait for each other. However, this framework |
121 |
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* supports other methods and techniques (for example the use of |
122 |
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* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that |
123 |
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* may be of use in constructing custom subclasses for problems that |
124 |
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* are not statically structured as DAGs. |
125 |
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* |
126 |
dl |
1.32 |
* <p>Most base support methods are {@code final}, to prevent |
127 |
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* overriding of implementations that are intrinsically tied to the |
128 |
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* underlying lightweight task scheduling framework. Developers |
129 |
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* creating new basic styles of fork/join processing should minimally |
130 |
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* implement {@code protected} methods {@link #exec}, {@link |
131 |
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* #setRawResult}, and {@link #getRawResult}, while also introducing |
132 |
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* an abstract computational method that can be implemented in its |
133 |
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* subclasses, possibly relying on other {@code protected} methods |
134 |
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* provided by this class. |
135 |
dl |
1.1 |
* |
136 |
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* <p>ForkJoinTasks should perform relatively small amounts of |
137 |
dl |
1.32 |
* computation. Large tasks should be split into smaller subtasks, |
138 |
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* usually via recursive decomposition. As a very rough rule of thumb, |
139 |
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* a task should perform more than 100 and less than 10000 basic |
140 |
dl |
1.70 |
* computational steps, and should avoid indefinite looping. If tasks |
141 |
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* are too big, then parallelism cannot improve throughput. If too |
142 |
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* small, then memory and internal task maintenance overhead may |
143 |
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* overwhelm processing. |
144 |
dl |
1.1 |
* |
145 |
jsr166 |
1.37 |
* <p>This class provides {@code adapt} methods for {@link Runnable} |
146 |
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* and {@link Callable}, that may be of use when mixing execution of |
147 |
dl |
1.49 |
* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are |
148 |
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* of this form, consider using a pool constructed in <em>asyncMode</em>. |
149 |
dl |
1.27 |
* |
150 |
dl |
1.32 |
* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
151 |
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* used in extensions such as remote execution frameworks. It is |
152 |
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* sensible to serialize tasks only before or after, but not during, |
153 |
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* execution. Serialization is not relied on during execution itself. |
154 |
jsr166 |
1.12 |
* |
155 |
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* @since 1.7 |
156 |
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* @author Doug Lea |
157 |
dl |
1.1 |
*/ |
158 |
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public abstract class ForkJoinTask<V> implements Future<V>, Serializable { |
159 |
dl |
1.2 |
|
160 |
dl |
1.46 |
/* |
161 |
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* See the internal documentation of class ForkJoinPool for a |
162 |
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* general implementation overview. ForkJoinTasks are mainly |
163 |
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* responsible for maintaining their "status" field amidst relays |
164 |
jsr166 |
1.80 |
* to methods in ForkJoinWorkerThread and ForkJoinPool. |
165 |
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* |
166 |
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* The methods of this class are more-or-less layered into |
167 |
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* (1) basic status maintenance |
168 |
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* (2) execution and awaiting completion |
169 |
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* (3) user-level methods that additionally report results. |
170 |
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* This is sometimes hard to see because this file orders exported |
171 |
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* methods in a way that flows well in javadocs. |
172 |
dl |
1.46 |
*/ |
173 |
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|
174 |
dl |
1.50 |
/* |
175 |
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* The status field holds run control status bits packed into a |
176 |
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* single int to minimize footprint and to ensure atomicity (via |
177 |
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* CAS). Status is initially zero, and takes on nonnegative |
178 |
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* values until completed, upon which status holds value |
179 |
jsr166 |
1.59 |
* NORMAL, CANCELLED, or EXCEPTIONAL. Tasks undergoing blocking |
180 |
dl |
1.50 |
* waits by other threads have the SIGNAL bit set. Completion of |
181 |
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* a stolen task with SIGNAL set awakens any waiters via |
182 |
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* notifyAll. Even though suboptimal for some purposes, we use |
183 |
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* basic builtin wait/notify to take advantage of "monitor |
184 |
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* inflation" in JVMs that we would otherwise need to emulate to |
185 |
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* avoid adding further per-task bookkeeping overhead. We want |
186 |
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* these monitors to be "fat", i.e., not use biasing or thin-lock |
187 |
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* techniques, so use some odd coding idioms that tend to avoid |
188 |
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* them. |
189 |
dl |
1.1 |
*/ |
190 |
dl |
1.50 |
|
191 |
dl |
1.53 |
/** The run status of this task */ |
192 |
jsr166 |
1.9 |
volatile int status; // accessed directly by pool and workers |
193 |
dl |
1.49 |
private static final int NORMAL = -1; |
194 |
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private static final int CANCELLED = -2; |
195 |
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private static final int EXCEPTIONAL = -3; |
196 |
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private static final int SIGNAL = 1; |
197 |
dl |
1.1 |
|
198 |
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/** |
199 |
dl |
1.46 |
* Marks completion and wakes up threads waiting to join this task, |
200 |
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* also clearing signal request bits. |
201 |
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* |
202 |
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* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL |
203 |
dl |
1.74 |
* @return completion status on exit |
204 |
dl |
1.1 |
*/ |
205 |
dl |
1.74 |
private int setCompletion(int completion) { |
206 |
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for (int s;;) { |
207 |
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if ((s = status) < 0) |
208 |
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return s; |
209 |
dl |
1.46 |
if (UNSAFE.compareAndSwapInt(this, statusOffset, s, completion)) { |
210 |
dl |
1.51 |
if (s != 0) |
211 |
dl |
1.46 |
synchronized (this) { notifyAll(); } |
212 |
dl |
1.74 |
return completion; |
213 |
dl |
1.46 |
} |
214 |
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} |
215 |
dl |
1.1 |
} |
216 |
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|
217 |
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/** |
218 |
dl |
1.74 |
* Tries to block a worker thread until completed or timed out. |
219 |
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* Uses Object.wait time argument conventions. |
220 |
|
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* May fail on contention or interrupt. |
221 |
jsr166 |
1.60 |
* |
222 |
dl |
1.74 |
* @param millis if > 0, wait time. |
223 |
dl |
1.1 |
*/ |
224 |
dl |
1.74 |
final void tryAwaitDone(long millis) { |
225 |
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int s; |
226 |
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try { |
227 |
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if (((s = status) > 0 || |
228 |
|
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(s == 0 && |
229 |
|
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UNSAFE.compareAndSwapInt(this, statusOffset, 0, SIGNAL))) && |
230 |
|
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status > 0) { |
231 |
jsr166 |
1.61 |
synchronized (this) { |
232 |
dl |
1.72 |
if (status > 0) |
233 |
dl |
1.74 |
wait(millis); |
234 |
dl |
1.1 |
} |
235 |
|
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} |
236 |
dl |
1.74 |
} catch (InterruptedException ie) { |
237 |
|
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// caller must check termination |
238 |
dl |
1.1 |
} |
239 |
|
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} |
240 |
|
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|
241 |
|
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/** |
242 |
dl |
1.70 |
* Blocks a non-worker-thread until completion. |
243 |
dl |
1.74 |
* @return status upon completion |
244 |
dl |
1.55 |
*/ |
245 |
dl |
1.74 |
private int externalAwaitDone() { |
246 |
|
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int s; |
247 |
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if ((s = status) >= 0) { |
248 |
dl |
1.70 |
boolean interrupted = false; |
249 |
jsr166 |
1.73 |
synchronized (this) { |
250 |
dl |
1.74 |
while ((s = status) >= 0) { |
251 |
dl |
1.72 |
if (s == 0) |
252 |
|
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UNSAFE.compareAndSwapInt(this, statusOffset, |
253 |
|
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0, SIGNAL); |
254 |
|
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else { |
255 |
|
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try { |
256 |
|
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wait(); |
257 |
|
|
} catch (InterruptedException ie) { |
258 |
|
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interrupted = true; |
259 |
|
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} |
260 |
dl |
1.70 |
} |
261 |
dl |
1.55 |
} |
262 |
|
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} |
263 |
dl |
1.70 |
if (interrupted) |
264 |
|
|
Thread.currentThread().interrupt(); |
265 |
dl |
1.55 |
} |
266 |
dl |
1.74 |
return s; |
267 |
dl |
1.55 |
} |
268 |
|
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|
269 |
|
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/** |
270 |
dl |
1.71 |
* Blocks a non-worker-thread until completion or interruption or timeout. |
271 |
dl |
1.1 |
*/ |
272 |
dl |
1.74 |
private int externalInterruptibleAwaitDone(long millis) |
273 |
dl |
1.70 |
throws InterruptedException { |
274 |
dl |
1.74 |
int s; |
275 |
dl |
1.70 |
if (Thread.interrupted()) |
276 |
|
|
throw new InterruptedException(); |
277 |
dl |
1.74 |
if ((s = status) >= 0) { |
278 |
jsr166 |
1.73 |
synchronized (this) { |
279 |
dl |
1.74 |
while ((s = status) >= 0) { |
280 |
dl |
1.72 |
if (s == 0) |
281 |
|
|
UNSAFE.compareAndSwapInt(this, statusOffset, |
282 |
|
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0, SIGNAL); |
283 |
dl |
1.75 |
else { |
284 |
dl |
1.74 |
wait(millis); |
285 |
dl |
1.75 |
if (millis > 0L) |
286 |
|
|
break; |
287 |
|
|
} |
288 |
dl |
1.74 |
} |
289 |
|
|
} |
290 |
|
|
} |
291 |
|
|
return s; |
292 |
|
|
} |
293 |
|
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|
294 |
|
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/** |
295 |
|
|
* Primary execution method for stolen tasks. Unless done, calls |
296 |
|
|
* exec and records status if completed, but doesn't wait for |
297 |
|
|
* completion otherwise. |
298 |
|
|
*/ |
299 |
|
|
final void doExec() { |
300 |
|
|
if (status >= 0) { |
301 |
|
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boolean completed; |
302 |
|
|
try { |
303 |
|
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completed = exec(); |
304 |
|
|
} catch (Throwable rex) { |
305 |
|
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setExceptionalCompletion(rex); |
306 |
|
|
return; |
307 |
|
|
} |
308 |
|
|
if (completed) |
309 |
|
|
setCompletion(NORMAL); // must be outside try block |
310 |
|
|
} |
311 |
|
|
} |
312 |
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|
313 |
|
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/** |
314 |
|
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* Primary mechanics for join, get, quietlyJoin. |
315 |
|
|
* @return status upon completion |
316 |
|
|
*/ |
317 |
|
|
private int doJoin() { |
318 |
|
|
Thread t; ForkJoinWorkerThread w; int s; boolean completed; |
319 |
|
|
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) { |
320 |
|
|
if ((s = status) < 0) |
321 |
|
|
return s; |
322 |
|
|
if ((w = (ForkJoinWorkerThread)t).unpushTask(this)) { |
323 |
|
|
try { |
324 |
|
|
completed = exec(); |
325 |
|
|
} catch (Throwable rex) { |
326 |
|
|
return setExceptionalCompletion(rex); |
327 |
dl |
1.46 |
} |
328 |
dl |
1.74 |
if (completed) |
329 |
|
|
return setCompletion(NORMAL); |
330 |
dl |
1.1 |
} |
331 |
dl |
1.74 |
return w.joinTask(this); |
332 |
dl |
1.1 |
} |
333 |
dl |
1.74 |
else |
334 |
|
|
return externalAwaitDone(); |
335 |
dl |
1.1 |
} |
336 |
|
|
|
337 |
|
|
/** |
338 |
dl |
1.74 |
* Primary mechanics for invoke, quietlyInvoke. |
339 |
|
|
* @return status upon completion |
340 |
dl |
1.1 |
*/ |
341 |
dl |
1.74 |
private int doInvoke() { |
342 |
|
|
int s; boolean completed; |
343 |
|
|
if ((s = status) < 0) |
344 |
|
|
return s; |
345 |
dl |
1.48 |
try { |
346 |
dl |
1.74 |
completed = exec(); |
347 |
dl |
1.48 |
} catch (Throwable rex) { |
348 |
dl |
1.74 |
return setExceptionalCompletion(rex); |
349 |
|
|
} |
350 |
|
|
if (completed) |
351 |
|
|
return setCompletion(NORMAL); |
352 |
|
|
else |
353 |
|
|
return doJoin(); |
354 |
|
|
} |
355 |
|
|
|
356 |
|
|
// Exception table support |
357 |
|
|
|
358 |
|
|
/** |
359 |
|
|
* Table of exceptions thrown by tasks, to enable reporting by |
360 |
|
|
* callers. Because exceptions are rare, we don't directly keep |
361 |
|
|
* them with task objects, but instead use a weak ref table. Note |
362 |
|
|
* that cancellation exceptions don't appear in the table, but are |
363 |
|
|
* instead recorded as status values. |
364 |
|
|
* |
365 |
|
|
* Note: These statics are initialized below in static block. |
366 |
|
|
*/ |
367 |
|
|
private static final ExceptionNode[] exceptionTable; |
368 |
|
|
private static final ReentrantLock exceptionTableLock; |
369 |
|
|
private static final ReferenceQueue<Object> exceptionTableRefQueue; |
370 |
|
|
|
371 |
|
|
/** |
372 |
|
|
* Fixed capacity for exceptionTable. |
373 |
|
|
*/ |
374 |
|
|
private static final int EXCEPTION_MAP_CAPACITY = 32; |
375 |
|
|
|
376 |
|
|
/** |
377 |
|
|
* Key-value nodes for exception table. The chained hash table |
378 |
|
|
* uses identity comparisons, full locking, and weak references |
379 |
|
|
* for keys. The table has a fixed capacity because it only |
380 |
|
|
* maintains task exceptions long enough for joiners to access |
381 |
|
|
* them, so should never become very large for sustained |
382 |
|
|
* periods. However, since we do not know when the last joiner |
383 |
|
|
* completes, we must use weak references and expunge them. We do |
384 |
|
|
* so on each operation (hence full locking). Also, some thread in |
385 |
dl |
1.76 |
* any ForkJoinPool will call helpExpungeStaleExceptions when its |
386 |
|
|
* pool becomes isQuiescent. |
387 |
dl |
1.74 |
*/ |
388 |
|
|
static final class ExceptionNode extends WeakReference<ForkJoinTask<?>>{ |
389 |
|
|
final Throwable ex; |
390 |
|
|
ExceptionNode next; |
391 |
dl |
1.76 |
final long thrower; // use id not ref to avoid weak cycles |
392 |
dl |
1.74 |
ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) { |
393 |
|
|
super(task, exceptionTableRefQueue); |
394 |
|
|
this.ex = ex; |
395 |
|
|
this.next = next; |
396 |
|
|
this.thrower = Thread.currentThread().getId(); |
397 |
|
|
} |
398 |
|
|
} |
399 |
|
|
|
400 |
|
|
/** |
401 |
|
|
* Records exception and sets exceptional completion. |
402 |
|
|
* |
403 |
|
|
* @return status on exit |
404 |
|
|
*/ |
405 |
|
|
private int setExceptionalCompletion(Throwable ex) { |
406 |
|
|
int h = System.identityHashCode(this); |
407 |
dl |
1.76 |
final ReentrantLock lock = exceptionTableLock; |
408 |
dl |
1.74 |
lock.lock(); |
409 |
|
|
try { |
410 |
|
|
expungeStaleExceptions(); |
411 |
|
|
ExceptionNode[] t = exceptionTable; |
412 |
|
|
int i = h & (t.length - 1); |
413 |
|
|
for (ExceptionNode e = t[i]; ; e = e.next) { |
414 |
|
|
if (e == null) { |
415 |
|
|
t[i] = new ExceptionNode(this, ex, t[i]); |
416 |
|
|
break; |
417 |
|
|
} |
418 |
|
|
if (e.get() == this) // already present |
419 |
|
|
break; |
420 |
|
|
} |
421 |
|
|
} finally { |
422 |
|
|
lock.unlock(); |
423 |
|
|
} |
424 |
|
|
return setCompletion(EXCEPTIONAL); |
425 |
|
|
} |
426 |
|
|
|
427 |
|
|
/** |
428 |
|
|
* Removes exception node and clears status |
429 |
|
|
*/ |
430 |
|
|
private void clearExceptionalCompletion() { |
431 |
|
|
int h = System.identityHashCode(this); |
432 |
dl |
1.76 |
final ReentrantLock lock = exceptionTableLock; |
433 |
dl |
1.74 |
lock.lock(); |
434 |
|
|
try { |
435 |
|
|
ExceptionNode[] t = exceptionTable; |
436 |
|
|
int i = h & (t.length - 1); |
437 |
|
|
ExceptionNode e = t[i]; |
438 |
|
|
ExceptionNode pred = null; |
439 |
|
|
while (e != null) { |
440 |
|
|
ExceptionNode next = e.next; |
441 |
|
|
if (e.get() == this) { |
442 |
|
|
if (pred == null) |
443 |
|
|
t[i] = next; |
444 |
|
|
else |
445 |
|
|
pred.next = next; |
446 |
|
|
break; |
447 |
|
|
} |
448 |
|
|
pred = e; |
449 |
|
|
e = next; |
450 |
|
|
} |
451 |
|
|
expungeStaleExceptions(); |
452 |
|
|
status = 0; |
453 |
|
|
} finally { |
454 |
|
|
lock.unlock(); |
455 |
|
|
} |
456 |
|
|
} |
457 |
|
|
|
458 |
|
|
/** |
459 |
|
|
* Returns a rethrowable exception for the given task, if |
460 |
|
|
* available. To provide accurate stack traces, if the exception |
461 |
|
|
* was not thrown by the current thread, we try to create a new |
462 |
|
|
* exception of the same type as the one thrown, but with the |
463 |
|
|
* recorded exception as its cause. If there is no such |
464 |
|
|
* constructor, we instead try to use a no-arg constructor, |
465 |
|
|
* followed by initCause, to the same effect. If none of these |
466 |
|
|
* apply, or any fail due to other exceptions, we return the |
467 |
|
|
* recorded exception, which is still correct, although it may |
468 |
|
|
* contain a misleading stack trace. |
469 |
|
|
* |
470 |
|
|
* @return the exception, or null if none |
471 |
|
|
*/ |
472 |
|
|
private Throwable getThrowableException() { |
473 |
|
|
if (status != EXCEPTIONAL) |
474 |
|
|
return null; |
475 |
|
|
int h = System.identityHashCode(this); |
476 |
|
|
ExceptionNode e; |
477 |
dl |
1.76 |
final ReentrantLock lock = exceptionTableLock; |
478 |
dl |
1.74 |
lock.lock(); |
479 |
|
|
try { |
480 |
|
|
expungeStaleExceptions(); |
481 |
|
|
ExceptionNode[] t = exceptionTable; |
482 |
|
|
e = t[h & (t.length - 1)]; |
483 |
|
|
while (e != null && e.get() != this) |
484 |
|
|
e = e.next; |
485 |
|
|
} finally { |
486 |
|
|
lock.unlock(); |
487 |
|
|
} |
488 |
|
|
Throwable ex; |
489 |
|
|
if (e == null || (ex = e.ex) == null) |
490 |
|
|
return null; |
491 |
|
|
if (e.thrower != Thread.currentThread().getId()) { |
492 |
jsr166 |
1.78 |
Class<? extends Throwable> ec = ex.getClass(); |
493 |
dl |
1.74 |
try { |
494 |
|
|
Constructor<?> noArgCtor = null; |
495 |
|
|
Constructor<?>[] cs = ec.getConstructors();// public ctors only |
496 |
|
|
for (int i = 0; i < cs.length; ++i) { |
497 |
|
|
Constructor<?> c = cs[i]; |
498 |
|
|
Class<?>[] ps = c.getParameterTypes(); |
499 |
|
|
if (ps.length == 0) |
500 |
|
|
noArgCtor = c; |
501 |
|
|
else if (ps.length == 1 && ps[0] == Throwable.class) |
502 |
|
|
return (Throwable)(c.newInstance(ex)); |
503 |
|
|
} |
504 |
|
|
if (noArgCtor != null) { |
505 |
|
|
Throwable wx = (Throwable)(noArgCtor.newInstance()); |
506 |
|
|
wx.initCause(ex); |
507 |
|
|
return wx; |
508 |
|
|
} |
509 |
|
|
} catch (Exception ignore) { |
510 |
|
|
} |
511 |
|
|
} |
512 |
|
|
return ex; |
513 |
|
|
} |
514 |
|
|
|
515 |
|
|
/** |
516 |
|
|
* Poll stale refs and remove them. Call only while holding lock. |
517 |
|
|
*/ |
518 |
|
|
private static void expungeStaleExceptions() { |
519 |
|
|
for (Object x; (x = exceptionTableRefQueue.poll()) != null;) { |
520 |
|
|
if (x instanceof ExceptionNode) { |
521 |
|
|
ForkJoinTask<?> key = ((ExceptionNode)x).get(); |
522 |
|
|
ExceptionNode[] t = exceptionTable; |
523 |
|
|
int i = System.identityHashCode(key) & (t.length - 1); |
524 |
|
|
ExceptionNode e = t[i]; |
525 |
|
|
ExceptionNode pred = null; |
526 |
|
|
while (e != null) { |
527 |
|
|
ExceptionNode next = e.next; |
528 |
|
|
if (e == x) { |
529 |
|
|
if (pred == null) |
530 |
|
|
t[i] = next; |
531 |
|
|
else |
532 |
|
|
pred.next = next; |
533 |
|
|
break; |
534 |
|
|
} |
535 |
|
|
pred = e; |
536 |
|
|
e = next; |
537 |
|
|
} |
538 |
|
|
} |
539 |
|
|
} |
540 |
|
|
} |
541 |
|
|
|
542 |
|
|
/** |
543 |
dl |
1.76 |
* If lock is available, poll stale refs and remove them. |
544 |
dl |
1.74 |
* Called from ForkJoinPool when pools become quiescent. |
545 |
|
|
*/ |
546 |
|
|
static final void helpExpungeStaleExceptions() { |
547 |
dl |
1.76 |
final ReentrantLock lock = exceptionTableLock; |
548 |
dl |
1.74 |
if (lock.tryLock()) { |
549 |
|
|
try { |
550 |
|
|
expungeStaleExceptions(); |
551 |
|
|
} finally { |
552 |
|
|
lock.unlock(); |
553 |
|
|
} |
554 |
dl |
1.1 |
} |
555 |
dl |
1.74 |
} |
556 |
|
|
|
557 |
|
|
/** |
558 |
|
|
* Report the result of invoke or join; called only upon |
559 |
|
|
* non-normal return of internal versions. |
560 |
|
|
*/ |
561 |
|
|
private V reportResult() { |
562 |
|
|
int s; Throwable ex; |
563 |
|
|
if ((s = status) == CANCELLED) |
564 |
|
|
throw new CancellationException(); |
565 |
|
|
if (s == EXCEPTIONAL && (ex = getThrowableException()) != null) |
566 |
|
|
UNSAFE.throwException(ex); |
567 |
|
|
return getRawResult(); |
568 |
dl |
1.1 |
} |
569 |
|
|
|
570 |
|
|
// public methods |
571 |
|
|
|
572 |
|
|
/** |
573 |
|
|
* Arranges to asynchronously execute this task. While it is not |
574 |
|
|
* necessarily enforced, it is a usage error to fork a task more |
575 |
jsr166 |
1.31 |
* than once unless it has completed and been reinitialized. |
576 |
dl |
1.43 |
* Subsequent modifications to the state of this task or any data |
577 |
|
|
* it operates on are not necessarily consistently observable by |
578 |
|
|
* any thread other than the one executing it unless preceded by a |
579 |
|
|
* call to {@link #join} or related methods, or a call to {@link |
580 |
|
|
* #isDone} returning {@code true}. |
581 |
dl |
1.18 |
* |
582 |
jsr166 |
1.31 |
* <p>This method may be invoked only from within {@code |
583 |
dl |
1.70 |
* ForkJoinPool} computations (as may be determined using method |
584 |
jsr166 |
1.31 |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
585 |
|
|
* result in exceptions or errors, possibly including {@code |
586 |
|
|
* ClassCastException}. |
587 |
|
|
* |
588 |
|
|
* @return {@code this}, to simplify usage |
589 |
dl |
1.1 |
*/ |
590 |
dl |
1.18 |
public final ForkJoinTask<V> fork() { |
591 |
jsr166 |
1.14 |
((ForkJoinWorkerThread) Thread.currentThread()) |
592 |
|
|
.pushTask(this); |
593 |
dl |
1.18 |
return this; |
594 |
dl |
1.1 |
} |
595 |
|
|
|
596 |
|
|
/** |
597 |
dl |
1.69 |
* Returns the result of the computation when it {@link #isDone is |
598 |
|
|
* done}. This method differs from {@link #get()} in that |
599 |
jsr166 |
1.31 |
* abnormal completion results in {@code RuntimeException} or |
600 |
dl |
1.69 |
* {@code Error}, not {@code ExecutionException}, and that |
601 |
|
|
* interrupts of the calling thread do <em>not</em> cause the |
602 |
|
|
* method to abruptly return by throwing {@code |
603 |
|
|
* InterruptedException}. |
604 |
dl |
1.1 |
* |
605 |
|
|
* @return the computed result |
606 |
|
|
*/ |
607 |
|
|
public final V join() { |
608 |
dl |
1.74 |
if (doJoin() != NORMAL) |
609 |
|
|
return reportResult(); |
610 |
|
|
else |
611 |
|
|
return getRawResult(); |
612 |
dl |
1.1 |
} |
613 |
|
|
|
614 |
|
|
/** |
615 |
dl |
1.2 |
* Commences performing this task, awaits its completion if |
616 |
jsr166 |
1.56 |
* necessary, and returns its result, or throws an (unchecked) |
617 |
dl |
1.57 |
* {@code RuntimeException} or {@code Error} if the underlying |
618 |
|
|
* computation did so. |
619 |
jsr166 |
1.10 |
* |
620 |
dl |
1.1 |
* @return the computed result |
621 |
|
|
*/ |
622 |
|
|
public final V invoke() { |
623 |
dl |
1.74 |
if (doInvoke() != NORMAL) |
624 |
|
|
return reportResult(); |
625 |
|
|
else |
626 |
|
|
return getRawResult(); |
627 |
dl |
1.1 |
} |
628 |
|
|
|
629 |
|
|
/** |
630 |
dl |
1.34 |
* Forks the given tasks, returning when {@code isDone} holds for |
631 |
|
|
* each task or an (unchecked) exception is encountered, in which |
632 |
dl |
1.57 |
* case the exception is rethrown. If more than one task |
633 |
|
|
* encounters an exception, then this method throws any one of |
634 |
|
|
* these exceptions. If any task encounters an exception, the |
635 |
|
|
* other may be cancelled. However, the execution status of |
636 |
|
|
* individual tasks is not guaranteed upon exceptional return. The |
637 |
|
|
* status of each task may be obtained using {@link |
638 |
|
|
* #getException()} and related methods to check if they have been |
639 |
|
|
* cancelled, completed normally or exceptionally, or left |
640 |
|
|
* unprocessed. |
641 |
jsr166 |
1.31 |
* |
642 |
|
|
* <p>This method may be invoked only from within {@code |
643 |
dl |
1.69 |
* ForkJoinPool} computations (as may be determined using method |
644 |
jsr166 |
1.31 |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
645 |
|
|
* result in exceptions or errors, possibly including {@code |
646 |
|
|
* ClassCastException}. |
647 |
jsr166 |
1.10 |
* |
648 |
dl |
1.27 |
* @param t1 the first task |
649 |
|
|
* @param t2 the second task |
650 |
|
|
* @throws NullPointerException if any task is null |
651 |
dl |
1.1 |
*/ |
652 |
jsr166 |
1.31 |
public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) { |
653 |
dl |
1.2 |
t2.fork(); |
654 |
|
|
t1.invoke(); |
655 |
|
|
t2.join(); |
656 |
dl |
1.1 |
} |
657 |
|
|
|
658 |
|
|
/** |
659 |
dl |
1.27 |
* Forks the given tasks, returning when {@code isDone} holds for |
660 |
dl |
1.34 |
* each task or an (unchecked) exception is encountered, in which |
661 |
dl |
1.57 |
* case the exception is rethrown. If more than one task |
662 |
|
|
* encounters an exception, then this method throws any one of |
663 |
|
|
* these exceptions. If any task encounters an exception, others |
664 |
|
|
* may be cancelled. However, the execution status of individual |
665 |
|
|
* tasks is not guaranteed upon exceptional return. The status of |
666 |
|
|
* each task may be obtained using {@link #getException()} and |
667 |
|
|
* related methods to check if they have been cancelled, completed |
668 |
|
|
* normally or exceptionally, or left unprocessed. |
669 |
jsr166 |
1.31 |
* |
670 |
|
|
* <p>This method may be invoked only from within {@code |
671 |
dl |
1.69 |
* ForkJoinPool} computations (as may be determined using method |
672 |
jsr166 |
1.31 |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
673 |
|
|
* result in exceptions or errors, possibly including {@code |
674 |
|
|
* ClassCastException}. |
675 |
jsr166 |
1.14 |
* |
676 |
dl |
1.27 |
* @param tasks the tasks |
677 |
dl |
1.34 |
* @throws NullPointerException if any task is null |
678 |
dl |
1.1 |
*/ |
679 |
dl |
1.2 |
public static void invokeAll(ForkJoinTask<?>... tasks) { |
680 |
|
|
Throwable ex = null; |
681 |
|
|
int last = tasks.length - 1; |
682 |
|
|
for (int i = last; i >= 0; --i) { |
683 |
|
|
ForkJoinTask<?> t = tasks[i]; |
684 |
|
|
if (t == null) { |
685 |
|
|
if (ex == null) |
686 |
|
|
ex = new NullPointerException(); |
687 |
|
|
} |
688 |
|
|
else if (i != 0) |
689 |
|
|
t.fork(); |
690 |
dl |
1.74 |
else if (t.doInvoke() < NORMAL && ex == null) |
691 |
|
|
ex = t.getException(); |
692 |
dl |
1.2 |
} |
693 |
|
|
for (int i = 1; i <= last; ++i) { |
694 |
|
|
ForkJoinTask<?> t = tasks[i]; |
695 |
|
|
if (t != null) { |
696 |
|
|
if (ex != null) |
697 |
|
|
t.cancel(false); |
698 |
jsr166 |
1.80 |
else if (t.doJoin() < NORMAL) |
699 |
dl |
1.74 |
ex = t.getException(); |
700 |
dl |
1.2 |
} |
701 |
dl |
1.1 |
} |
702 |
dl |
1.2 |
if (ex != null) |
703 |
dl |
1.46 |
UNSAFE.throwException(ex); |
704 |
dl |
1.1 |
} |
705 |
|
|
|
706 |
|
|
/** |
707 |
dl |
1.32 |
* Forks all tasks in the specified collection, returning when |
708 |
dl |
1.34 |
* {@code isDone} holds for each task or an (unchecked) exception |
709 |
dl |
1.57 |
* is encountered, in which case the exception is rethrown. If |
710 |
|
|
* more than one task encounters an exception, then this method |
711 |
|
|
* throws any one of these exceptions. If any task encounters an |
712 |
|
|
* exception, others may be cancelled. However, the execution |
713 |
|
|
* status of individual tasks is not guaranteed upon exceptional |
714 |
|
|
* return. The status of each task may be obtained using {@link |
715 |
|
|
* #getException()} and related methods to check if they have been |
716 |
|
|
* cancelled, completed normally or exceptionally, or left |
717 |
|
|
* unprocessed. |
718 |
jsr166 |
1.31 |
* |
719 |
|
|
* <p>This method may be invoked only from within {@code |
720 |
dl |
1.69 |
* ForkJoinPool} computations (as may be determined using method |
721 |
jsr166 |
1.31 |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
722 |
|
|
* result in exceptions or errors, possibly including {@code |
723 |
|
|
* ClassCastException}. |
724 |
jsr166 |
1.10 |
* |
725 |
dl |
1.2 |
* @param tasks the collection of tasks |
726 |
dl |
1.19 |
* @return the tasks argument, to simplify usage |
727 |
jsr166 |
1.10 |
* @throws NullPointerException if tasks or any element are null |
728 |
dl |
1.1 |
*/ |
729 |
dl |
1.19 |
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
730 |
dl |
1.32 |
if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) { |
731 |
jsr166 |
1.14 |
invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()])); |
732 |
dl |
1.19 |
return tasks; |
733 |
dl |
1.2 |
} |
734 |
jsr166 |
1.15 |
@SuppressWarnings("unchecked") |
735 |
dl |
1.2 |
List<? extends ForkJoinTask<?>> ts = |
736 |
jsr166 |
1.14 |
(List<? extends ForkJoinTask<?>>) tasks; |
737 |
dl |
1.2 |
Throwable ex = null; |
738 |
|
|
int last = ts.size() - 1; |
739 |
|
|
for (int i = last; i >= 0; --i) { |
740 |
|
|
ForkJoinTask<?> t = ts.get(i); |
741 |
|
|
if (t == null) { |
742 |
|
|
if (ex == null) |
743 |
|
|
ex = new NullPointerException(); |
744 |
|
|
} |
745 |
|
|
else if (i != 0) |
746 |
|
|
t.fork(); |
747 |
dl |
1.74 |
else if (t.doInvoke() < NORMAL && ex == null) |
748 |
|
|
ex = t.getException(); |
749 |
dl |
1.2 |
} |
750 |
|
|
for (int i = 1; i <= last; ++i) { |
751 |
|
|
ForkJoinTask<?> t = ts.get(i); |
752 |
|
|
if (t != null) { |
753 |
|
|
if (ex != null) |
754 |
|
|
t.cancel(false); |
755 |
jsr166 |
1.80 |
else if (t.doJoin() < NORMAL) |
756 |
dl |
1.74 |
ex = t.getException(); |
757 |
dl |
1.2 |
} |
758 |
|
|
} |
759 |
|
|
if (ex != null) |
760 |
dl |
1.46 |
UNSAFE.throwException(ex); |
761 |
dl |
1.19 |
return tasks; |
762 |
dl |
1.1 |
} |
763 |
|
|
|
764 |
|
|
/** |
765 |
dl |
1.33 |
* Attempts to cancel execution of this task. This attempt will |
766 |
dl |
1.69 |
* fail if the task has already completed or could not be |
767 |
|
|
* cancelled for some other reason. If successful, and this task |
768 |
|
|
* has not started when {@code cancel} is called, execution of |
769 |
|
|
* this task is suppressed. After this method returns |
770 |
|
|
* successfully, unless there is an intervening call to {@link |
771 |
|
|
* #reinitialize}, subsequent calls to {@link #isCancelled}, |
772 |
|
|
* {@link #isDone}, and {@code cancel} will return {@code true} |
773 |
|
|
* and calls to {@link #join} and related methods will result in |
774 |
|
|
* {@code CancellationException}. |
775 |
dl |
1.1 |
* |
776 |
|
|
* <p>This method may be overridden in subclasses, but if so, must |
777 |
dl |
1.69 |
* still ensure that these properties hold. In particular, the |
778 |
|
|
* {@code cancel} method itself must not throw exceptions. |
779 |
dl |
1.1 |
* |
780 |
jsr166 |
1.28 |
* <p>This method is designed to be invoked by <em>other</em> |
781 |
dl |
1.1 |
* tasks. To terminate the current task, you can just return or |
782 |
|
|
* throw an unchecked exception from its computation method, or |
783 |
jsr166 |
1.24 |
* invoke {@link #completeExceptionally}. |
784 |
dl |
1.1 |
* |
785 |
dl |
1.69 |
* @param mayInterruptIfRunning this value has no effect in the |
786 |
|
|
* default implementation because interrupts are not used to |
787 |
|
|
* control cancellation. |
788 |
dl |
1.1 |
* |
789 |
jsr166 |
1.23 |
* @return {@code true} if this task is now cancelled |
790 |
dl |
1.1 |
*/ |
791 |
|
|
public boolean cancel(boolean mayInterruptIfRunning) { |
792 |
dl |
1.74 |
return setCompletion(CANCELLED) == CANCELLED; |
793 |
dl |
1.1 |
} |
794 |
|
|
|
795 |
dl |
1.46 |
/** |
796 |
dl |
1.52 |
* Cancels, ignoring any exceptions thrown by cancel. Used during |
797 |
|
|
* worker and pool shutdown. Cancel is spec'ed not to throw any |
798 |
|
|
* exceptions, but if it does anyway, we have no recourse during |
799 |
|
|
* shutdown, so guard against this case. |
800 |
dl |
1.46 |
*/ |
801 |
|
|
final void cancelIgnoringExceptions() { |
802 |
|
|
try { |
803 |
|
|
cancel(false); |
804 |
|
|
} catch (Throwable ignore) { |
805 |
|
|
} |
806 |
|
|
} |
807 |
|
|
|
808 |
dl |
1.34 |
public final boolean isDone() { |
809 |
|
|
return status < 0; |
810 |
|
|
} |
811 |
|
|
|
812 |
|
|
public final boolean isCancelled() { |
813 |
dl |
1.49 |
return status == CANCELLED; |
814 |
dl |
1.34 |
} |
815 |
|
|
|
816 |
|
|
/** |
817 |
jsr166 |
1.23 |
* Returns {@code true} if this task threw an exception or was cancelled. |
818 |
jsr166 |
1.10 |
* |
819 |
jsr166 |
1.23 |
* @return {@code true} if this task threw an exception or was cancelled |
820 |
dl |
1.3 |
*/ |
821 |
|
|
public final boolean isCompletedAbnormally() { |
822 |
dl |
1.49 |
return status < NORMAL; |
823 |
dl |
1.3 |
} |
824 |
|
|
|
825 |
|
|
/** |
826 |
dl |
1.34 |
* Returns {@code true} if this task completed without throwing an |
827 |
|
|
* exception and was not cancelled. |
828 |
|
|
* |
829 |
|
|
* @return {@code true} if this task completed without throwing an |
830 |
|
|
* exception and was not cancelled |
831 |
|
|
*/ |
832 |
|
|
public final boolean isCompletedNormally() { |
833 |
dl |
1.49 |
return status == NORMAL; |
834 |
dl |
1.34 |
} |
835 |
|
|
|
836 |
|
|
/** |
837 |
dl |
1.3 |
* Returns the exception thrown by the base computation, or a |
838 |
jsr166 |
1.29 |
* {@code CancellationException} if cancelled, or {@code null} if |
839 |
|
|
* none or if the method has not yet completed. |
840 |
jsr166 |
1.10 |
* |
841 |
jsr166 |
1.23 |
* @return the exception, or {@code null} if none |
842 |
dl |
1.3 |
*/ |
843 |
|
|
public final Throwable getException() { |
844 |
dl |
1.49 |
int s = status; |
845 |
jsr166 |
1.37 |
return ((s >= NORMAL) ? null : |
846 |
|
|
(s == CANCELLED) ? new CancellationException() : |
847 |
dl |
1.74 |
getThrowableException()); |
848 |
dl |
1.3 |
} |
849 |
|
|
|
850 |
|
|
/** |
851 |
dl |
1.1 |
* Completes this task abnormally, and if not already aborted or |
852 |
|
|
* cancelled, causes it to throw the given exception upon |
853 |
jsr166 |
1.8 |
* {@code join} and related operations. This method may be used |
854 |
dl |
1.1 |
* to induce exceptions in asynchronous tasks, or to force |
855 |
dl |
1.2 |
* completion of tasks that would not otherwise complete. Its use |
856 |
dl |
1.27 |
* in other situations is discouraged. This method is |
857 |
jsr166 |
1.8 |
* overridable, but overridden versions must invoke {@code super} |
858 |
dl |
1.2 |
* implementation to maintain guarantees. |
859 |
|
|
* |
860 |
jsr166 |
1.44 |
* @param ex the exception to throw. If this exception is not a |
861 |
|
|
* {@code RuntimeException} or {@code Error}, the actual exception |
862 |
|
|
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
863 |
dl |
1.1 |
*/ |
864 |
|
|
public void completeExceptionally(Throwable ex) { |
865 |
dl |
1.48 |
setExceptionalCompletion((ex instanceof RuntimeException) || |
866 |
|
|
(ex instanceof Error) ? ex : |
867 |
|
|
new RuntimeException(ex)); |
868 |
dl |
1.1 |
} |
869 |
|
|
|
870 |
|
|
/** |
871 |
|
|
* Completes this task, and if not already aborted or cancelled, |
872 |
dl |
1.58 |
* returning the given value as the result of subsequent |
873 |
|
|
* invocations of {@code join} and related operations. This method |
874 |
|
|
* may be used to provide results for asynchronous tasks, or to |
875 |
|
|
* provide alternative handling for tasks that would not otherwise |
876 |
|
|
* complete normally. Its use in other situations is |
877 |
|
|
* discouraged. This method is overridable, but overridden |
878 |
|
|
* versions must invoke {@code super} implementation to maintain |
879 |
|
|
* guarantees. |
880 |
dl |
1.1 |
* |
881 |
jsr166 |
1.10 |
* @param value the result value for this task |
882 |
dl |
1.1 |
*/ |
883 |
|
|
public void complete(V value) { |
884 |
|
|
try { |
885 |
|
|
setRawResult(value); |
886 |
jsr166 |
1.14 |
} catch (Throwable rex) { |
887 |
dl |
1.48 |
setExceptionalCompletion(rex); |
888 |
dl |
1.1 |
return; |
889 |
|
|
} |
890 |
dl |
1.46 |
setCompletion(NORMAL); |
891 |
dl |
1.1 |
} |
892 |
|
|
|
893 |
dl |
1.62 |
/** |
894 |
dl |
1.63 |
* Waits if necessary for the computation to complete, and then |
895 |
|
|
* retrieves its result. |
896 |
|
|
* |
897 |
|
|
* @return the computed result |
898 |
|
|
* @throws CancellationException if the computation was cancelled |
899 |
|
|
* @throws ExecutionException if the computation threw an |
900 |
|
|
* exception |
901 |
|
|
* @throws InterruptedException if the current thread is not a |
902 |
|
|
* member of a ForkJoinPool and was interrupted while waiting |
903 |
dl |
1.62 |
*/ |
904 |
dl |
1.3 |
public final V get() throws InterruptedException, ExecutionException { |
905 |
dl |
1.74 |
int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ? |
906 |
|
|
doJoin() : externalInterruptibleAwaitDone(0L); |
907 |
|
|
Throwable ex; |
908 |
|
|
if (s == CANCELLED) |
909 |
|
|
throw new CancellationException(); |
910 |
|
|
if (s == EXCEPTIONAL && (ex = getThrowableException()) != null) |
911 |
|
|
throw new ExecutionException(ex); |
912 |
dl |
1.48 |
return getRawResult(); |
913 |
dl |
1.3 |
} |
914 |
dl |
1.47 |
|
915 |
dl |
1.62 |
/** |
916 |
dl |
1.63 |
* Waits if necessary for at most the given time for the computation |
917 |
|
|
* to complete, and then retrieves its result, if available. |
918 |
|
|
* |
919 |
|
|
* @param timeout the maximum time to wait |
920 |
|
|
* @param unit the time unit of the timeout argument |
921 |
|
|
* @return the computed result |
922 |
|
|
* @throws CancellationException if the computation was cancelled |
923 |
|
|
* @throws ExecutionException if the computation threw an |
924 |
|
|
* exception |
925 |
|
|
* @throws InterruptedException if the current thread is not a |
926 |
|
|
* member of a ForkJoinPool and was interrupted while waiting |
927 |
|
|
* @throws TimeoutException if the wait timed out |
928 |
dl |
1.62 |
*/ |
929 |
dl |
1.3 |
public final V get(long timeout, TimeUnit unit) |
930 |
|
|
throws InterruptedException, ExecutionException, TimeoutException { |
931 |
dl |
1.70 |
Thread t = Thread.currentThread(); |
932 |
dl |
1.74 |
if (t instanceof ForkJoinWorkerThread) { |
933 |
|
|
ForkJoinWorkerThread w = (ForkJoinWorkerThread) t; |
934 |
|
|
long nanos = unit.toNanos(timeout); |
935 |
|
|
if (status >= 0) { |
936 |
|
|
boolean completed = false; |
937 |
|
|
if (w.unpushTask(this)) { |
938 |
|
|
try { |
939 |
|
|
completed = exec(); |
940 |
|
|
} catch (Throwable rex) { |
941 |
|
|
setExceptionalCompletion(rex); |
942 |
|
|
} |
943 |
|
|
} |
944 |
|
|
if (completed) |
945 |
|
|
setCompletion(NORMAL); |
946 |
|
|
else if (status >= 0 && nanos > 0) |
947 |
|
|
w.pool.timedAwaitJoin(this, nanos); |
948 |
|
|
} |
949 |
|
|
} |
950 |
|
|
else { |
951 |
|
|
long millis = unit.toMillis(timeout); |
952 |
|
|
if (millis > 0) |
953 |
|
|
externalInterruptibleAwaitDone(millis); |
954 |
|
|
} |
955 |
dl |
1.70 |
int s = status; |
956 |
|
|
if (s != NORMAL) { |
957 |
dl |
1.48 |
Throwable ex; |
958 |
dl |
1.70 |
if (s == CANCELLED) |
959 |
dl |
1.48 |
throw new CancellationException(); |
960 |
dl |
1.74 |
if (s != EXCEPTIONAL) |
961 |
|
|
throw new TimeoutException(); |
962 |
|
|
if ((ex = getThrowableException()) != null) |
963 |
dl |
1.48 |
throw new ExecutionException(ex); |
964 |
|
|
} |
965 |
|
|
return getRawResult(); |
966 |
dl |
1.3 |
} |
967 |
|
|
|
968 |
dl |
1.1 |
/** |
969 |
dl |
1.53 |
* Joins this task, without returning its result or throwing its |
970 |
dl |
1.2 |
* exception. This method may be useful when processing |
971 |
|
|
* collections of tasks when some have been cancelled or otherwise |
972 |
|
|
* known to have aborted. |
973 |
|
|
*/ |
974 |
|
|
public final void quietlyJoin() { |
975 |
dl |
1.74 |
doJoin(); |
976 |
dl |
1.2 |
} |
977 |
|
|
|
978 |
|
|
/** |
979 |
|
|
* Commences performing this task and awaits its completion if |
980 |
dl |
1.53 |
* necessary, without returning its result or throwing its |
981 |
dl |
1.58 |
* exception. |
982 |
dl |
1.2 |
*/ |
983 |
|
|
public final void quietlyInvoke() { |
984 |
dl |
1.74 |
doInvoke(); |
985 |
dl |
1.2 |
} |
986 |
|
|
|
987 |
|
|
/** |
988 |
dl |
1.3 |
* Possibly executes tasks until the pool hosting the current task |
989 |
dl |
1.33 |
* {@link ForkJoinPool#isQuiescent is quiescent}. This method may |
990 |
|
|
* be of use in designs in which many tasks are forked, but none |
991 |
|
|
* are explicitly joined, instead executing them until all are |
992 |
|
|
* processed. |
993 |
jsr166 |
1.31 |
* |
994 |
|
|
* <p>This method may be invoked only from within {@code |
995 |
dl |
1.69 |
* ForkJoinPool} computations (as may be determined using method |
996 |
jsr166 |
1.31 |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
997 |
|
|
* result in exceptions or errors, possibly including {@code |
998 |
|
|
* ClassCastException}. |
999 |
dl |
1.3 |
*/ |
1000 |
|
|
public static void helpQuiesce() { |
1001 |
jsr166 |
1.14 |
((ForkJoinWorkerThread) Thread.currentThread()) |
1002 |
|
|
.helpQuiescePool(); |
1003 |
dl |
1.3 |
} |
1004 |
|
|
|
1005 |
|
|
/** |
1006 |
dl |
1.1 |
* Resets the internal bookkeeping state of this task, allowing a |
1007 |
jsr166 |
1.8 |
* subsequent {@code fork}. This method allows repeated reuse of |
1008 |
dl |
1.1 |
* this task, but only if reuse occurs when this task has either |
1009 |
|
|
* never been forked, or has been forked, then completed and all |
1010 |
|
|
* outstanding joins of this task have also completed. Effects |
1011 |
dl |
1.30 |
* under any other usage conditions are not guaranteed. |
1012 |
|
|
* This method may be useful when executing |
1013 |
dl |
1.1 |
* pre-constructed trees of subtasks in loops. |
1014 |
jsr166 |
1.68 |
* |
1015 |
dl |
1.67 |
* <p>Upon completion of this method, {@code isDone()} reports |
1016 |
|
|
* {@code false}, and {@code getException()} reports {@code |
1017 |
|
|
* null}. However, the value returned by {@code getRawResult} is |
1018 |
|
|
* unaffected. To clear this value, you can invoke {@code |
1019 |
|
|
* setRawResult(null)}. |
1020 |
dl |
1.1 |
*/ |
1021 |
|
|
public void reinitialize() { |
1022 |
dl |
1.49 |
if (status == EXCEPTIONAL) |
1023 |
dl |
1.74 |
clearExceptionalCompletion(); |
1024 |
|
|
else |
1025 |
|
|
status = 0; |
1026 |
dl |
1.1 |
} |
1027 |
|
|
|
1028 |
|
|
/** |
1029 |
dl |
1.2 |
* Returns the pool hosting the current task execution, or null |
1030 |
dl |
1.13 |
* if this task is executing outside of any ForkJoinPool. |
1031 |
jsr166 |
1.10 |
* |
1032 |
dl |
1.27 |
* @see #inForkJoinPool |
1033 |
jsr166 |
1.23 |
* @return the pool, or {@code null} if none |
1034 |
dl |
1.1 |
*/ |
1035 |
dl |
1.2 |
public static ForkJoinPool getPool() { |
1036 |
|
|
Thread t = Thread.currentThread(); |
1037 |
jsr166 |
1.15 |
return (t instanceof ForkJoinWorkerThread) ? |
1038 |
|
|
((ForkJoinWorkerThread) t).pool : null; |
1039 |
dl |
1.1 |
} |
1040 |
|
|
|
1041 |
|
|
/** |
1042 |
dl |
1.71 |
* Returns {@code true} if the current thread is a {@link |
1043 |
|
|
* ForkJoinWorkerThread} executing as a ForkJoinPool computation. |
1044 |
jsr166 |
1.14 |
* |
1045 |
dl |
1.71 |
* @return {@code true} if the current thread is a {@link |
1046 |
|
|
* ForkJoinWorkerThread} executing as a ForkJoinPool computation, |
1047 |
|
|
* or {@code false} otherwise |
1048 |
dl |
1.13 |
*/ |
1049 |
|
|
public static boolean inForkJoinPool() { |
1050 |
|
|
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
1051 |
|
|
} |
1052 |
|
|
|
1053 |
|
|
/** |
1054 |
dl |
1.2 |
* Tries to unschedule this task for execution. This method will |
1055 |
|
|
* typically succeed if this task is the most recently forked task |
1056 |
|
|
* by the current thread, and has not commenced executing in |
1057 |
|
|
* another thread. This method may be useful when arranging |
1058 |
|
|
* alternative local processing of tasks that could have been, but |
1059 |
jsr166 |
1.31 |
* were not, stolen. |
1060 |
|
|
* |
1061 |
|
|
* <p>This method may be invoked only from within {@code |
1062 |
dl |
1.69 |
* ForkJoinPool} computations (as may be determined using method |
1063 |
jsr166 |
1.31 |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1064 |
|
|
* result in exceptions or errors, possibly including {@code |
1065 |
|
|
* ClassCastException}. |
1066 |
jsr166 |
1.10 |
* |
1067 |
jsr166 |
1.23 |
* @return {@code true} if unforked |
1068 |
dl |
1.1 |
*/ |
1069 |
dl |
1.2 |
public boolean tryUnfork() { |
1070 |
jsr166 |
1.14 |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1071 |
|
|
.unpushTask(this); |
1072 |
dl |
1.1 |
} |
1073 |
|
|
|
1074 |
|
|
/** |
1075 |
dl |
1.2 |
* Returns an estimate of the number of tasks that have been |
1076 |
|
|
* forked by the current worker thread but not yet executed. This |
1077 |
|
|
* value may be useful for heuristic decisions about whether to |
1078 |
jsr166 |
1.31 |
* fork other tasks. |
1079 |
|
|
* |
1080 |
|
|
* <p>This method may be invoked only from within {@code |
1081 |
dl |
1.69 |
* ForkJoinPool} computations (as may be determined using method |
1082 |
jsr166 |
1.31 |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1083 |
|
|
* result in exceptions or errors, possibly including {@code |
1084 |
|
|
* ClassCastException}. |
1085 |
|
|
* |
1086 |
dl |
1.2 |
* @return the number of tasks |
1087 |
|
|
*/ |
1088 |
|
|
public static int getQueuedTaskCount() { |
1089 |
jsr166 |
1.14 |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1090 |
|
|
.getQueueSize(); |
1091 |
dl |
1.2 |
} |
1092 |
|
|
|
1093 |
|
|
/** |
1094 |
jsr166 |
1.10 |
* Returns an estimate of how many more locally queued tasks are |
1095 |
dl |
1.1 |
* held by the current worker thread than there are other worker |
1096 |
dl |
1.2 |
* threads that might steal them. This value may be useful for |
1097 |
|
|
* heuristic decisions about whether to fork other tasks. In many |
1098 |
|
|
* usages of ForkJoinTasks, at steady state, each worker should |
1099 |
|
|
* aim to maintain a small constant surplus (for example, 3) of |
1100 |
|
|
* tasks, and to process computations locally if this threshold is |
1101 |
jsr166 |
1.31 |
* exceeded. |
1102 |
|
|
* |
1103 |
|
|
* <p>This method may be invoked only from within {@code |
1104 |
dl |
1.69 |
* ForkJoinPool} computations (as may be determined using method |
1105 |
jsr166 |
1.31 |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1106 |
|
|
* result in exceptions or errors, possibly including {@code |
1107 |
|
|
* ClassCastException}. |
1108 |
|
|
* |
1109 |
dl |
1.1 |
* @return the surplus number of tasks, which may be negative |
1110 |
|
|
*/ |
1111 |
dl |
1.2 |
public static int getSurplusQueuedTaskCount() { |
1112 |
jsr166 |
1.14 |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1113 |
dl |
1.1 |
.getEstimatedSurplusTaskCount(); |
1114 |
|
|
} |
1115 |
|
|
|
1116 |
dl |
1.2 |
// Extension methods |
1117 |
dl |
1.1 |
|
1118 |
|
|
/** |
1119 |
jsr166 |
1.23 |
* Returns the result that would be returned by {@link #join}, even |
1120 |
|
|
* if this task completed abnormally, or {@code null} if this task |
1121 |
|
|
* is not known to have been completed. This method is designed |
1122 |
|
|
* to aid debugging, as well as to support extensions. Its use in |
1123 |
|
|
* any other context is discouraged. |
1124 |
dl |
1.1 |
* |
1125 |
jsr166 |
1.23 |
* @return the result, or {@code null} if not completed |
1126 |
dl |
1.1 |
*/ |
1127 |
|
|
public abstract V getRawResult(); |
1128 |
|
|
|
1129 |
|
|
/** |
1130 |
|
|
* Forces the given value to be returned as a result. This method |
1131 |
|
|
* is designed to support extensions, and should not in general be |
1132 |
|
|
* called otherwise. |
1133 |
|
|
* |
1134 |
|
|
* @param value the value |
1135 |
|
|
*/ |
1136 |
|
|
protected abstract void setRawResult(V value); |
1137 |
|
|
|
1138 |
|
|
/** |
1139 |
|
|
* Immediately performs the base action of this task. This method |
1140 |
|
|
* is designed to support extensions, and should not in general be |
1141 |
|
|
* called otherwise. The return value controls whether this task |
1142 |
|
|
* is considered to be done normally. It may return false in |
1143 |
|
|
* asynchronous actions that require explicit invocations of |
1144 |
dl |
1.34 |
* {@link #complete} to become joinable. It may also throw an |
1145 |
|
|
* (unchecked) exception to indicate abnormal exit. |
1146 |
jsr166 |
1.10 |
* |
1147 |
jsr166 |
1.23 |
* @return {@code true} if completed normally |
1148 |
dl |
1.1 |
*/ |
1149 |
|
|
protected abstract boolean exec(); |
1150 |
|
|
|
1151 |
dl |
1.2 |
/** |
1152 |
dl |
1.25 |
* Returns, but does not unschedule or execute, a task queued by |
1153 |
|
|
* the current thread but not yet executed, if one is immediately |
1154 |
dl |
1.6 |
* available. There is no guarantee that this task will actually |
1155 |
dl |
1.25 |
* be polled or executed next. Conversely, this method may return |
1156 |
|
|
* null even if a task exists but cannot be accessed without |
1157 |
|
|
* contention with other threads. This method is designed |
1158 |
|
|
* primarily to support extensions, and is unlikely to be useful |
1159 |
jsr166 |
1.31 |
* otherwise. |
1160 |
|
|
* |
1161 |
|
|
* <p>This method may be invoked only from within {@code |
1162 |
dl |
1.69 |
* ForkJoinPool} computations (as may be determined using method |
1163 |
jsr166 |
1.31 |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1164 |
|
|
* result in exceptions or errors, possibly including {@code |
1165 |
|
|
* ClassCastException}. |
1166 |
dl |
1.2 |
* |
1167 |
jsr166 |
1.23 |
* @return the next task, or {@code null} if none are available |
1168 |
dl |
1.2 |
*/ |
1169 |
|
|
protected static ForkJoinTask<?> peekNextLocalTask() { |
1170 |
jsr166 |
1.14 |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1171 |
|
|
.peekTask(); |
1172 |
dl |
1.2 |
} |
1173 |
|
|
|
1174 |
|
|
/** |
1175 |
dl |
1.6 |
* Unschedules and returns, without executing, the next task |
1176 |
|
|
* queued by the current thread but not yet executed. This method |
1177 |
|
|
* is designed primarily to support extensions, and is unlikely to |
1178 |
jsr166 |
1.31 |
* be useful otherwise. |
1179 |
|
|
* |
1180 |
|
|
* <p>This method may be invoked only from within {@code |
1181 |
dl |
1.69 |
* ForkJoinPool} computations (as may be determined using method |
1182 |
jsr166 |
1.31 |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1183 |
|
|
* result in exceptions or errors, possibly including {@code |
1184 |
|
|
* ClassCastException}. |
1185 |
dl |
1.2 |
* |
1186 |
jsr166 |
1.23 |
* @return the next task, or {@code null} if none are available |
1187 |
dl |
1.2 |
*/ |
1188 |
|
|
protected static ForkJoinTask<?> pollNextLocalTask() { |
1189 |
jsr166 |
1.14 |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1190 |
|
|
.pollLocalTask(); |
1191 |
dl |
1.2 |
} |
1192 |
jsr166 |
1.7 |
|
1193 |
dl |
1.2 |
/** |
1194 |
dl |
1.6 |
* Unschedules and returns, without executing, the next task |
1195 |
|
|
* queued by the current thread but not yet executed, if one is |
1196 |
|
|
* available, or if not available, a task that was forked by some |
1197 |
|
|
* other thread, if available. Availability may be transient, so a |
1198 |
jsr166 |
1.9 |
* {@code null} result does not necessarily imply quiescence |
1199 |
dl |
1.6 |
* of the pool this task is operating in. This method is designed |
1200 |
|
|
* primarily to support extensions, and is unlikely to be useful |
1201 |
jsr166 |
1.31 |
* otherwise. |
1202 |
|
|
* |
1203 |
|
|
* <p>This method may be invoked only from within {@code |
1204 |
dl |
1.69 |
* ForkJoinPool} computations (as may be determined using method |
1205 |
jsr166 |
1.31 |
* {@link #inForkJoinPool}). Attempts to invoke in other contexts |
1206 |
|
|
* result in exceptions or errors, possibly including {@code |
1207 |
|
|
* ClassCastException}. |
1208 |
dl |
1.4 |
* |
1209 |
jsr166 |
1.23 |
* @return a task, or {@code null} if none are available |
1210 |
dl |
1.2 |
*/ |
1211 |
|
|
protected static ForkJoinTask<?> pollTask() { |
1212 |
jsr166 |
1.14 |
return ((ForkJoinWorkerThread) Thread.currentThread()) |
1213 |
|
|
.pollTask(); |
1214 |
dl |
1.2 |
} |
1215 |
|
|
|
1216 |
dl |
1.25 |
/** |
1217 |
|
|
* Adaptor for Runnables. This implements RunnableFuture |
1218 |
|
|
* to be compliant with AbstractExecutorService constraints |
1219 |
|
|
* when used in ForkJoinPool. |
1220 |
|
|
*/ |
1221 |
|
|
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
1222 |
|
|
implements RunnableFuture<T> { |
1223 |
|
|
final Runnable runnable; |
1224 |
|
|
final T resultOnCompletion; |
1225 |
|
|
T result; |
1226 |
|
|
AdaptedRunnable(Runnable runnable, T result) { |
1227 |
|
|
if (runnable == null) throw new NullPointerException(); |
1228 |
|
|
this.runnable = runnable; |
1229 |
|
|
this.resultOnCompletion = result; |
1230 |
|
|
} |
1231 |
|
|
public T getRawResult() { return result; } |
1232 |
|
|
public void setRawResult(T v) { result = v; } |
1233 |
|
|
public boolean exec() { |
1234 |
|
|
runnable.run(); |
1235 |
|
|
result = resultOnCompletion; |
1236 |
|
|
return true; |
1237 |
|
|
} |
1238 |
|
|
public void run() { invoke(); } |
1239 |
|
|
private static final long serialVersionUID = 5232453952276885070L; |
1240 |
|
|
} |
1241 |
|
|
|
1242 |
|
|
/** |
1243 |
|
|
* Adaptor for Callables |
1244 |
|
|
*/ |
1245 |
|
|
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
1246 |
|
|
implements RunnableFuture<T> { |
1247 |
dl |
1.27 |
final Callable<? extends T> callable; |
1248 |
dl |
1.25 |
T result; |
1249 |
dl |
1.27 |
AdaptedCallable(Callable<? extends T> callable) { |
1250 |
dl |
1.25 |
if (callable == null) throw new NullPointerException(); |
1251 |
|
|
this.callable = callable; |
1252 |
|
|
} |
1253 |
|
|
public T getRawResult() { return result; } |
1254 |
|
|
public void setRawResult(T v) { result = v; } |
1255 |
|
|
public boolean exec() { |
1256 |
|
|
try { |
1257 |
|
|
result = callable.call(); |
1258 |
|
|
return true; |
1259 |
|
|
} catch (Error err) { |
1260 |
|
|
throw err; |
1261 |
|
|
} catch (RuntimeException rex) { |
1262 |
|
|
throw rex; |
1263 |
|
|
} catch (Exception ex) { |
1264 |
|
|
throw new RuntimeException(ex); |
1265 |
|
|
} |
1266 |
|
|
} |
1267 |
|
|
public void run() { invoke(); } |
1268 |
|
|
private static final long serialVersionUID = 2838392045355241008L; |
1269 |
|
|
} |
1270 |
dl |
1.18 |
|
1271 |
|
|
/** |
1272 |
jsr166 |
1.31 |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1273 |
|
|
* method of the given {@code Runnable} as its action, and returns |
1274 |
|
|
* a null result upon {@link #join}. |
1275 |
dl |
1.18 |
* |
1276 |
|
|
* @param runnable the runnable action |
1277 |
|
|
* @return the task |
1278 |
|
|
*/ |
1279 |
dl |
1.27 |
public static ForkJoinTask<?> adapt(Runnable runnable) { |
1280 |
dl |
1.25 |
return new AdaptedRunnable<Void>(runnable, null); |
1281 |
dl |
1.18 |
} |
1282 |
|
|
|
1283 |
|
|
/** |
1284 |
jsr166 |
1.31 |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1285 |
|
|
* method of the given {@code Runnable} as its action, and returns |
1286 |
|
|
* the given result upon {@link #join}. |
1287 |
dl |
1.18 |
* |
1288 |
|
|
* @param runnable the runnable action |
1289 |
|
|
* @param result the result upon completion |
1290 |
|
|
* @return the task |
1291 |
|
|
*/ |
1292 |
|
|
public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) { |
1293 |
dl |
1.25 |
return new AdaptedRunnable<T>(runnable, result); |
1294 |
dl |
1.18 |
} |
1295 |
|
|
|
1296 |
|
|
/** |
1297 |
jsr166 |
1.31 |
* Returns a new {@code ForkJoinTask} that performs the {@code call} |
1298 |
|
|
* method of the given {@code Callable} as its action, and returns |
1299 |
|
|
* its result upon {@link #join}, translating any checked exceptions |
1300 |
|
|
* encountered into {@code RuntimeException}. |
1301 |
dl |
1.18 |
* |
1302 |
|
|
* @param callable the callable action |
1303 |
|
|
* @return the task |
1304 |
|
|
*/ |
1305 |
dl |
1.27 |
public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) { |
1306 |
dl |
1.25 |
return new AdaptedCallable<T>(callable); |
1307 |
dl |
1.18 |
} |
1308 |
|
|
|
1309 |
dl |
1.1 |
// Serialization support |
1310 |
|
|
|
1311 |
|
|
private static final long serialVersionUID = -7721805057305804111L; |
1312 |
|
|
|
1313 |
|
|
/** |
1314 |
jsr166 |
1.56 |
* Saves the state to a stream (that is, serializes it). |
1315 |
dl |
1.1 |
* |
1316 |
|
|
* @serialData the current run status and the exception thrown |
1317 |
jsr166 |
1.23 |
* during execution, or {@code null} if none |
1318 |
dl |
1.1 |
* @param s the stream |
1319 |
|
|
*/ |
1320 |
|
|
private void writeObject(java.io.ObjectOutputStream s) |
1321 |
|
|
throws java.io.IOException { |
1322 |
|
|
s.defaultWriteObject(); |
1323 |
|
|
s.writeObject(getException()); |
1324 |
|
|
} |
1325 |
|
|
|
1326 |
|
|
/** |
1327 |
jsr166 |
1.56 |
* Reconstitutes the instance from a stream (that is, deserializes it). |
1328 |
jsr166 |
1.10 |
* |
1329 |
dl |
1.1 |
* @param s the stream |
1330 |
|
|
*/ |
1331 |
|
|
private void readObject(java.io.ObjectInputStream s) |
1332 |
|
|
throws java.io.IOException, ClassNotFoundException { |
1333 |
|
|
s.defaultReadObject(); |
1334 |
|
|
Object ex = s.readObject(); |
1335 |
|
|
if (ex != null) |
1336 |
dl |
1.74 |
setExceptionalCompletion((Throwable)ex); |
1337 |
dl |
1.1 |
} |
1338 |
|
|
|
1339 |
jsr166 |
1.22 |
// Unsafe mechanics |
1340 |
dl |
1.74 |
private static final sun.misc.Unsafe UNSAFE; |
1341 |
|
|
private static final long statusOffset; |
1342 |
|
|
static { |
1343 |
|
|
exceptionTableLock = new ReentrantLock(); |
1344 |
|
|
exceptionTableRefQueue = new ReferenceQueue<Object>(); |
1345 |
|
|
exceptionTable = new ExceptionNode[EXCEPTION_MAP_CAPACITY]; |
1346 |
jsr166 |
1.22 |
try { |
1347 |
dl |
1.74 |
UNSAFE = getUnsafe(); |
1348 |
|
|
statusOffset = UNSAFE.objectFieldOffset |
1349 |
|
|
(ForkJoinTask.class.getDeclaredField("status")); |
1350 |
|
|
} catch (Exception e) { |
1351 |
|
|
throw new Error(e); |
1352 |
jsr166 |
1.22 |
} |
1353 |
|
|
} |
1354 |
|
|
|
1355 |
|
|
/** |
1356 |
|
|
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1357 |
|
|
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1358 |
|
|
* into a jdk. |
1359 |
|
|
* |
1360 |
|
|
* @return a sun.misc.Unsafe |
1361 |
|
|
*/ |
1362 |
jsr166 |
1.16 |
private static sun.misc.Unsafe getUnsafe() { |
1363 |
jsr166 |
1.5 |
try { |
1364 |
jsr166 |
1.16 |
return sun.misc.Unsafe.getUnsafe(); |
1365 |
jsr166 |
1.5 |
} catch (SecurityException se) { |
1366 |
|
|
try { |
1367 |
|
|
return java.security.AccessController.doPrivileged |
1368 |
jsr166 |
1.22 |
(new java.security |
1369 |
|
|
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1370 |
jsr166 |
1.16 |
public sun.misc.Unsafe run() throws Exception { |
1371 |
jsr166 |
1.22 |
java.lang.reflect.Field f = sun.misc |
1372 |
|
|
.Unsafe.class.getDeclaredField("theUnsafe"); |
1373 |
|
|
f.setAccessible(true); |
1374 |
|
|
return (sun.misc.Unsafe) f.get(null); |
1375 |
jsr166 |
1.5 |
}}); |
1376 |
|
|
} catch (java.security.PrivilegedActionException e) { |
1377 |
jsr166 |
1.16 |
throw new RuntimeException("Could not initialize intrinsics", |
1378 |
|
|
e.getCause()); |
1379 |
jsr166 |
1.5 |
} |
1380 |
|
|
} |
1381 |
|
|
} |
1382 |
dl |
1.1 |
} |