1 |
|
/* |
2 |
|
* Written by Doug Lea with assistance from members of JCP JSR-166 |
3 |
|
* Expert Group and released to the public domain, as explained at |
4 |
< |
* http://creativecommons.org/licenses/publicdomain |
4 |
> |
* http://creativecommons.org/publicdomain/zero/1.0/ |
5 |
|
*/ |
6 |
|
|
7 |
|
package jsr166y; |
8 |
+ |
|
9 |
|
import java.io.Serializable; |
10 |
< |
import java.util.*; |
11 |
< |
import java.util.concurrent.*; |
12 |
< |
import java.util.concurrent.atomic.*; |
13 |
< |
import sun.misc.Unsafe; |
14 |
< |
import java.lang.reflect.*; |
10 |
> |
import java.util.Collection; |
11 |
> |
import java.util.List; |
12 |
> |
import java.util.RandomAccess; |
13 |
> |
import java.lang.ref.WeakReference; |
14 |
> |
import java.lang.ref.ReferenceQueue; |
15 |
> |
import java.util.concurrent.Callable; |
16 |
> |
import java.util.concurrent.CancellationException; |
17 |
> |
import java.util.concurrent.ExecutionException; |
18 |
> |
import java.util.concurrent.Future; |
19 |
> |
import java.util.concurrent.RejectedExecutionException; |
20 |
> |
import java.util.concurrent.RunnableFuture; |
21 |
> |
import java.util.concurrent.TimeUnit; |
22 |
> |
import java.util.concurrent.TimeoutException; |
23 |
> |
import java.util.concurrent.locks.ReentrantLock; |
24 |
> |
import java.lang.reflect.Constructor; |
25 |
|
|
26 |
|
/** |
27 |
< |
* Abstract base class for tasks that run within a {@link |
28 |
< |
* ForkJoinPool}. A ForkJoinTask is a thread-like entity that is much |
27 |
> |
* Abstract base class for tasks that run within a {@link ForkJoinPool}. |
28 |
> |
* A {@code ForkJoinTask} is a thread-like entity that is much |
29 |
|
* lighter weight than a normal thread. Huge numbers of tasks and |
30 |
|
* subtasks may be hosted by a small number of actual threads in a |
31 |
|
* ForkJoinPool, at the price of some usage limitations. |
32 |
|
* |
33 |
< |
* <p> A "main" ForkJoinTask begins execution when submitted to a |
34 |
< |
* {@link ForkJoinPool}. Once started, it will usually in turn start |
35 |
< |
* other subtasks. As indicated by the name of this class, many |
36 |
< |
* programs using ForkJoinTasks employ only methods <code>fork</code> |
37 |
< |
* and <code>join</code>, or derivatives such as |
38 |
< |
* <code>invokeAll</code>. However, this class also provides a number |
39 |
< |
* of other methods that can come into play in advanced usages, as |
40 |
< |
* well as extension mechanics that allow support of new forms of |
41 |
< |
* fork/join processing. |
33 |
> |
* <p>A "main" {@code ForkJoinTask} begins execution when it is |
34 |
> |
* explicitly submitted to a {@link ForkJoinPool}, or, if not already |
35 |
> |
* engaged in a ForkJoin computation, commenced in the {@link |
36 |
> |
* ForkJoinPool#commonPool()} via {@link #fork}, {@link #invoke}, or |
37 |
> |
* related methods. Once started, it will usually in turn start other |
38 |
> |
* subtasks. As indicated by the name of this class, many programs |
39 |
> |
* using {@code ForkJoinTask} employ only methods {@link #fork} and |
40 |
> |
* {@link #join}, or derivatives such as {@link |
41 |
> |
* #invokeAll(ForkJoinTask...) invokeAll}. However, this class also |
42 |
> |
* provides a number of other methods that can come into play in |
43 |
> |
* advanced usages, as well as extension mechanics that allow support |
44 |
> |
* of new forms of fork/join processing. |
45 |
> |
* |
46 |
> |
* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}. |
47 |
> |
* The efficiency of {@code ForkJoinTask}s stems from a set of |
48 |
> |
* restrictions (that are only partially statically enforceable) |
49 |
> |
* reflecting their main use as computational tasks calculating pure |
50 |
> |
* functions or operating on purely isolated objects. The primary |
51 |
> |
* coordination mechanisms are {@link #fork}, that arranges |
52 |
> |
* asynchronous execution, and {@link #join}, that doesn't proceed |
53 |
> |
* until the task's result has been computed. Computations should |
54 |
> |
* ideally avoid {@code synchronized} methods or blocks, and should |
55 |
> |
* minimize other blocking synchronization apart from joining other |
56 |
> |
* tasks or using synchronizers such as Phasers that are advertised to |
57 |
> |
* cooperate with fork/join scheduling. Subdividable tasks should also |
58 |
> |
* not perform blocking I/O, and should ideally access variables that |
59 |
> |
* are completely independent of those accessed by other running |
60 |
> |
* tasks. These guidelines are loosely enforced by not permitting |
61 |
> |
* checked exceptions such as {@code IOExceptions} to be |
62 |
> |
* thrown. However, computations may still encounter unchecked |
63 |
> |
* exceptions, that are rethrown to callers attempting to join |
64 |
> |
* them. These exceptions may additionally include {@link |
65 |
> |
* RejectedExecutionException} stemming from internal resource |
66 |
> |
* exhaustion, such as failure to allocate internal task |
67 |
> |
* queues. Rethrown exceptions behave in the same way as regular |
68 |
> |
* exceptions, but, when possible, contain stack traces (as displayed |
69 |
> |
* for example using {@code ex.printStackTrace()}) of both the thread |
70 |
> |
* that initiated the computation as well as the thread actually |
71 |
> |
* encountering the exception; minimally only the latter. |
72 |
|
* |
73 |
< |
* <p>A ForkJoinTask is a lightweight form of {@link Future}. The |
74 |
< |
* efficiency of ForkJoinTasks stems from a set of restrictions (that |
75 |
< |
* are only partially statically enforceable) reflecting their |
76 |
< |
* intended use as computational tasks calculating pure functions or |
77 |
< |
* operating on purely isolated objects. The primary coordination |
78 |
< |
* mechanisms are {@link #fork}, that arranges asynchronous execution, |
79 |
< |
* and {@link #join}, that doesn't proceed until the task's result has |
80 |
< |
* been computed. Computations should avoid <code>synchronized</code> |
81 |
< |
* methods or blocks, and should minimize other blocking |
82 |
< |
* synchronization apart from joining other tasks or using |
83 |
< |
* synchronizers such as Phasers that are advertised to cooperate with |
84 |
< |
* fork/join scheduling. Tasks should also not perform blocking IO, |
85 |
< |
* and should ideally access variables that are completely independent |
45 |
< |
* of those accessed by other running tasks. Minor breaches of these |
46 |
< |
* restrictions, for example using shared output streams, may be |
47 |
< |
* tolerable in practice, but frequent use may result in poor |
48 |
< |
* performance, and the potential to indefinitely stall if the number |
49 |
< |
* of threads not waiting for IO or other external synchronization |
50 |
< |
* becomes exhausted. This usage restriction is in part enforced by |
51 |
< |
* not permitting checked exceptions such as <code>IOExceptions</code> |
52 |
< |
* to be thrown. However, computations may still encounter unchecked |
53 |
< |
* exceptions, that are rethrown to callers attempting join |
54 |
< |
* them. These exceptions may additionally include |
55 |
< |
* RejectedExecutionExceptions stemming from internal resource |
56 |
< |
* exhaustion such as failure to allocate internal task queues. |
73 |
> |
* <p>It is possible to define and use ForkJoinTasks that may block, |
74 |
> |
* but doing do requires three further considerations: (1) Completion |
75 |
> |
* of few if any <em>other</em> tasks should be dependent on a task |
76 |
> |
* that blocks on external synchronization or I/O. Event-style async |
77 |
> |
* tasks that are never joined (for example, those subclassing {@link |
78 |
> |
* CountedCompleter}) often fall into this category. (2) To minimize |
79 |
> |
* resource impact, tasks should be small; ideally performing only the |
80 |
> |
* (possibly) blocking action. (3) Unless the {@link |
81 |
> |
* ForkJoinPool.ManagedBlocker} API is used, or the number of possibly |
82 |
> |
* blocked tasks is known to be less than the pool's {@link |
83 |
> |
* ForkJoinPool#getParallelism} level, the pool cannot guarantee that |
84 |
> |
* enough threads will be available to ensure progress or good |
85 |
> |
* performance. |
86 |
|
* |
87 |
|
* <p>The primary method for awaiting completion and extracting |
88 |
|
* results of a task is {@link #join}, but there are several variants: |
89 |
|
* The {@link Future#get} methods support interruptible and/or timed |
90 |
< |
* waits for completion and report results using <code>Future</code> |
91 |
< |
* conventions. Method {@link #helpJoin} enables callers to actively |
92 |
< |
* execute other tasks while awaiting joins, which is sometimes more |
93 |
< |
* efficient but only applies when all subtasks are known to be |
94 |
< |
* strictly tree-structured. Method {@link #invoke} is semantically |
66 |
< |
* equivalent to <code>fork(); join()</code> but always attempts to |
67 |
< |
* begin execution in the current thread. The "<em>quiet</em>" forms |
68 |
< |
* of these methods do not extract results or report exceptions. These |
90 |
> |
* waits for completion and report results using {@code Future} |
91 |
> |
* conventions. Method {@link #invoke} is semantically |
92 |
> |
* equivalent to {@code fork(); join()} but always attempts to begin |
93 |
> |
* execution in the current thread. The "<em>quiet</em>" forms of |
94 |
> |
* these methods do not extract results or report exceptions. These |
95 |
|
* may be useful when a set of tasks are being executed, and you need |
96 |
|
* to delay processing of results or exceptions until all complete. |
97 |
< |
* Method <code>invokeAll</code> (available in multiple versions) |
97 |
> |
* Method {@code invokeAll} (available in multiple versions) |
98 |
|
* performs the most common form of parallel invocation: forking a set |
99 |
|
* of tasks and joining them all. |
100 |
|
* |
101 |
< |
* <p> The ForkJoinTask class is not usually directly subclassed. |
101 |
> |
* <p>In the most typical usages, a fork-join pair act like a call |
102 |
> |
* (fork) and return (join) from a parallel recursive function. As is |
103 |
> |
* the case with other forms of recursive calls, returns (joins) |
104 |
> |
* should be performed innermost-first. For example, {@code a.fork(); |
105 |
> |
* b.fork(); b.join(); a.join();} is likely to be substantially more |
106 |
> |
* efficient than joining {@code a} before {@code b}. |
107 |
> |
* |
108 |
> |
* <p>The execution status of tasks may be queried at several levels |
109 |
> |
* of detail: {@link #isDone} is true if a task completed in any way |
110 |
> |
* (including the case where a task was cancelled without executing); |
111 |
> |
* {@link #isCompletedNormally} is true if a task completed without |
112 |
> |
* cancellation or encountering an exception; {@link #isCancelled} is |
113 |
> |
* true if the task was cancelled (in which case {@link #getException} |
114 |
> |
* returns a {@link java.util.concurrent.CancellationException}); and |
115 |
> |
* {@link #isCompletedAbnormally} is true if a task was either |
116 |
> |
* cancelled or encountered an exception, in which case {@link |
117 |
> |
* #getException} will return either the encountered exception or |
118 |
> |
* {@link java.util.concurrent.CancellationException}. |
119 |
> |
* |
120 |
> |
* <p>The ForkJoinTask class is not usually directly subclassed. |
121 |
|
* Instead, you subclass one of the abstract classes that support a |
122 |
< |
* particular style of fork/join processing. Normally, a concrete |
123 |
< |
* ForkJoinTask subclass declares fields comprising its parameters, |
124 |
< |
* established in a constructor, and then defines a <code>compute</code> |
125 |
< |
* method that somehow uses the control methods supplied by this base |
126 |
< |
* class. While these methods have <code>public</code> access (to allow |
127 |
< |
* instances of different task subclasses to call each others |
128 |
< |
* methods), some of them may only be called from within other |
129 |
< |
* ForkJoinTasks. Attempts to invoke them in other contexts result in |
130 |
< |
* exceptions or errors possibly including ClassCastException. |
122 |
> |
* particular style of fork/join processing, typically {@link |
123 |
> |
* RecursiveAction} for most computations that do not return results, |
124 |
> |
* {@link RecursiveTask} for those that do, and {@link |
125 |
> |
* CountedCompleter} for those in which completed actions trigger |
126 |
> |
* other actions. Normally, a concrete ForkJoinTask subclass declares |
127 |
> |
* fields comprising its parameters, established in a constructor, and |
128 |
> |
* then defines a {@code compute} method that somehow uses the control |
129 |
> |
* methods supplied by this base class. |
130 |
> |
* |
131 |
> |
* <p>Method {@link #join} and its variants are appropriate for use |
132 |
> |
* only when completion dependencies are acyclic; that is, the |
133 |
> |
* parallel computation can be described as a directed acyclic graph |
134 |
> |
* (DAG). Otherwise, executions may encounter a form of deadlock as |
135 |
> |
* tasks cyclically wait for each other. However, this framework |
136 |
> |
* supports other methods and techniques (for example the use of |
137 |
> |
* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that |
138 |
> |
* may be of use in constructing custom subclasses for problems that |
139 |
> |
* are not statically structured as DAGs. To support such usages a |
140 |
> |
* ForkJoinTask may be atomically <em>tagged</em> with a {@code short} |
141 |
> |
* value using {@link #setForkJoinTaskTag} or {@link |
142 |
> |
* #compareAndSetForkJoinTaskTag} and checked using {@link |
143 |
> |
* #getForkJoinTaskTag}. The ForkJoinTask implementation does not use |
144 |
> |
* these {@code protected} methods or tags for any purpose, but they |
145 |
> |
* may be of use in the construction of specialized subclasses. For |
146 |
> |
* example, parallel graph traversals can use the supplied methods to |
147 |
> |
* avoid revisiting nodes/tasks that have already been processed. |
148 |
> |
* (Method names for tagging are bulky in part to encourage definition |
149 |
> |
* of methods that reflect their usage patterns.) |
150 |
|
* |
151 |
< |
* <p>Most base support methods are <code>final</code> because their |
152 |
< |
* implementations are intrinsically tied to the underlying |
153 |
< |
* lightweight task scheduling framework, and so cannot be overridden. |
154 |
< |
* Developers creating new basic styles of fork/join processing should |
155 |
< |
* minimally implement <code>protected</code> methods |
156 |
< |
* <code>exec</code>, <code>setRawResult</code>, and |
157 |
< |
* <code>getRawResult</code>, while also introducing an abstract |
158 |
< |
* computational method that can be implemented in its subclasses, |
159 |
< |
* possibly relying on other <code>protected</code> methods provided |
96 |
< |
* by this class. |
151 |
> |
* <p>Most base support methods are {@code final}, to prevent |
152 |
> |
* overriding of implementations that are intrinsically tied to the |
153 |
> |
* underlying lightweight task scheduling framework. Developers |
154 |
> |
* creating new basic styles of fork/join processing should minimally |
155 |
> |
* implement {@code protected} methods {@link #exec}, {@link |
156 |
> |
* #setRawResult}, and {@link #getRawResult}, while also introducing |
157 |
> |
* an abstract computational method that can be implemented in its |
158 |
> |
* subclasses, possibly relying on other {@code protected} methods |
159 |
> |
* provided by this class. |
160 |
|
* |
161 |
|
* <p>ForkJoinTasks should perform relatively small amounts of |
162 |
< |
* computations, othewise splitting into smaller tasks. As a very |
163 |
< |
* rough rule of thumb, a task should perform more than 100 and less |
164 |
< |
* than 10000 basic computational steps. If tasks are too big, then |
165 |
< |
* parellelism cannot improve throughput. If too small, then memory |
166 |
< |
* and internal task maintenance overhead may overwhelm processing. |
162 |
> |
* computation. Large tasks should be split into smaller subtasks, |
163 |
> |
* usually via recursive decomposition. As a very rough rule of thumb, |
164 |
> |
* a task should perform more than 100 and less than 10000 basic |
165 |
> |
* computational steps, and should avoid indefinite looping. If tasks |
166 |
> |
* are too big, then parallelism cannot improve throughput. If too |
167 |
> |
* small, then memory and internal task maintenance overhead may |
168 |
> |
* overwhelm processing. |
169 |
|
* |
170 |
< |
* <p>ForkJoinTasks are <code>Serializable</code>, which enables them |
171 |
< |
* to be used in extensions such as remote execution frameworks. It is |
172 |
< |
* in general sensible to serialize tasks only before or after, but |
173 |
< |
* not during execution. Serialization is not relied on during |
174 |
< |
* execution itself. |
170 |
> |
* <p>This class provides {@code adapt} methods for {@link Runnable} |
171 |
> |
* and {@link Callable}, that may be of use when mixing execution of |
172 |
> |
* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are |
173 |
> |
* of this form, consider using a pool constructed in <em>asyncMode</em>. |
174 |
> |
* |
175 |
> |
* <p>ForkJoinTasks are {@code Serializable}, which enables them to be |
176 |
> |
* used in extensions such as remote execution frameworks. It is |
177 |
> |
* sensible to serialize tasks only before or after, but not during, |
178 |
> |
* execution. Serialization is not relied on during execution itself. |
179 |
> |
* |
180 |
> |
* @since 1.7 |
181 |
> |
* @author Doug Lea |
182 |
|
*/ |
183 |
|
public abstract class ForkJoinTask<V> implements Future<V>, Serializable { |
184 |
|
|
185 |
< |
/** |
186 |
< |
* Run control status bits packed into a single int to minimize |
187 |
< |
* footprint and to ensure atomicity (via CAS). Status is |
188 |
< |
* initially zero, and takes on nonnegative values until |
189 |
< |
* completed, upon which status holds COMPLETED. CANCELLED, or |
190 |
< |
* EXCEPTIONAL, which use the top 3 bits. Tasks undergoing |
191 |
< |
* blocking waits by other threads have SIGNAL_MASK bits set -- |
192 |
< |
* bit 15 for external (nonFJ) waits, and the rest a count of |
193 |
< |
* waiting FJ threads. (This representation relies on |
194 |
< |
* ForkJoinPool max thread limits). Completion of a stolen task |
195 |
< |
* with SIGNAL_MASK bits set awakens waiter via notifyAll. Even |
196 |
< |
* though suboptimal for some purposes, we use basic builtin |
197 |
< |
* wait/notify to take advantage of "monitor inflation" in JVMs |
198 |
< |
* that we would otherwise need to emulate to avoid adding further |
199 |
< |
* per-task bookkeeping overhead. Note that bits 16-28 are |
200 |
< |
* currently unused. Also value 0x80000000 is available as spare |
201 |
< |
* completion value. |
202 |
< |
*/ |
203 |
< |
volatile int status; // accessed directy by pool and workers |
204 |
< |
|
205 |
< |
static final int COMPLETION_MASK = 0xe0000000; |
206 |
< |
static final int NORMAL = 0xe0000000; // == mask |
207 |
< |
static final int CANCELLED = 0xc0000000; |
208 |
< |
static final int EXCEPTIONAL = 0xa0000000; |
209 |
< |
static final int SIGNAL_MASK = 0x0000ffff; |
210 |
< |
static final int INTERNAL_SIGNAL_MASK = 0x00007fff; |
211 |
< |
static final int EXTERNAL_SIGNAL = 0x00008000; // top bit of low word |
185 |
> |
/* |
186 |
> |
* See the internal documentation of class ForkJoinPool for a |
187 |
> |
* general implementation overview. ForkJoinTasks are mainly |
188 |
> |
* responsible for maintaining their "status" field amidst relays |
189 |
> |
* to methods in ForkJoinWorkerThread and ForkJoinPool. |
190 |
> |
* |
191 |
> |
* The methods of this class are more-or-less layered into |
192 |
> |
* (1) basic status maintenance |
193 |
> |
* (2) execution and awaiting completion |
194 |
> |
* (3) user-level methods that additionally report results. |
195 |
> |
* This is sometimes hard to see because this file orders exported |
196 |
> |
* methods in a way that flows well in javadocs. |
197 |
> |
*/ |
198 |
> |
|
199 |
> |
/* |
200 |
> |
* The status field holds run control status bits packed into a |
201 |
> |
* single int to minimize footprint and to ensure atomicity (via |
202 |
> |
* CAS). Status is initially zero, and takes on nonnegative |
203 |
> |
* values until completed, upon which status (anded with |
204 |
> |
* DONE_MASK) holds value NORMAL, CANCELLED, or EXCEPTIONAL. Tasks |
205 |
> |
* undergoing blocking waits by other threads have the SIGNAL bit |
206 |
> |
* set. Completion of a stolen task with SIGNAL set awakens any |
207 |
> |
* waiters via notifyAll. Even though suboptimal for some |
208 |
> |
* purposes, we use basic builtin wait/notify to take advantage of |
209 |
> |
* "monitor inflation" in JVMs that we would otherwise need to |
210 |
> |
* emulate to avoid adding further per-task bookkeeping overhead. |
211 |
> |
* We want these monitors to be "fat", i.e., not use biasing or |
212 |
> |
* thin-lock techniques, so use some odd coding idioms that tend |
213 |
> |
* to avoid them, mainly by arranging that every synchronized |
214 |
> |
* block performs a wait, notifyAll or both. |
215 |
> |
* |
216 |
> |
* These control bits occupy only (some of) the upper half (16 |
217 |
> |
* bits) of status field. The lower bits are used for user-defined |
218 |
> |
* tags. |
219 |
> |
*/ |
220 |
> |
|
221 |
> |
/** The run status of this task */ |
222 |
> |
volatile int status; // accessed directly by pool and workers |
223 |
> |
static final int DONE_MASK = 0xf0000000; // mask out non-completion bits |
224 |
> |
static final int NORMAL = 0xf0000000; // must be negative |
225 |
> |
static final int CANCELLED = 0xc0000000; // must be < NORMAL |
226 |
> |
static final int EXCEPTIONAL = 0x80000000; // must be < CANCELLED |
227 |
> |
static final int SIGNAL = 0x00010000; // must be >= 1 << 16 |
228 |
> |
static final int SMASK = 0x0000ffff; // short bits for tags |
229 |
|
|
230 |
|
/** |
231 |
< |
* Table of exceptions thrown by tasks, to enable reporting by |
232 |
< |
* callers. Because exceptions are rare, we don't directly keep |
233 |
< |
* them with task objects, but instead us a weak ref table. Note |
234 |
< |
* that cancellation exceptions don't appear in the table, but are |
235 |
< |
* instead recorded as status values. |
147 |
< |
* Todo: Use ConcurrentReferenceHashMap |
231 |
> |
* Marks completion and wakes up threads waiting to join this |
232 |
> |
* task. |
233 |
> |
* |
234 |
> |
* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL |
235 |
> |
* @return completion status on exit |
236 |
|
*/ |
237 |
< |
static final Map<ForkJoinTask<?>, Throwable> exceptionMap = |
238 |
< |
Collections.synchronizedMap |
239 |
< |
(new WeakHashMap<ForkJoinTask<?>, Throwable>()); |
240 |
< |
|
241 |
< |
// within-package utilities |
237 |
> |
private int setCompletion(int completion) { |
238 |
> |
for (int s;;) { |
239 |
> |
if ((s = status) < 0) |
240 |
> |
return s; |
241 |
> |
if (U.compareAndSwapInt(this, STATUS, s, s | completion)) { |
242 |
> |
if ((s >>> 16) != 0) |
243 |
> |
synchronized (this) { notifyAll(); } |
244 |
> |
return completion; |
245 |
> |
} |
246 |
> |
} |
247 |
> |
} |
248 |
|
|
249 |
|
/** |
250 |
< |
* Get current worker thread, or null if not a worker thread |
250 |
> |
* Primary execution method for stolen tasks. Unless done, calls |
251 |
> |
* exec and records status if completed, but doesn't wait for |
252 |
> |
* completion otherwise. |
253 |
> |
* |
254 |
> |
* @return status on exit from this method |
255 |
|
*/ |
256 |
< |
static ForkJoinWorkerThread getWorker() { |
257 |
< |
Thread t = Thread.currentThread(); |
258 |
< |
return ((t instanceof ForkJoinWorkerThread)? |
259 |
< |
(ForkJoinWorkerThread)t : null); |
260 |
< |
} |
261 |
< |
|
262 |
< |
final boolean casStatus(int cmp, int val) { |
263 |
< |
return _unsafe.compareAndSwapInt(this, statusOffset, cmp, val); |
256 |
> |
final int doExec() { |
257 |
> |
int s; boolean completed; |
258 |
> |
if ((s = status) >= 0) { |
259 |
> |
try { |
260 |
> |
completed = exec(); |
261 |
> |
} catch (Throwable rex) { |
262 |
> |
return setExceptionalCompletion(rex); |
263 |
> |
} |
264 |
> |
if (completed) |
265 |
> |
s = setCompletion(NORMAL); |
266 |
> |
} |
267 |
> |
return s; |
268 |
|
} |
269 |
|
|
270 |
|
/** |
271 |
< |
* Workaround for not being able to rethrow unchecked exceptions. |
271 |
> |
* Tries to set SIGNAL status unless already completed. Used by |
272 |
> |
* ForkJoinPool. Other variants are directly incorporated into |
273 |
> |
* externalAwaitDone etc. |
274 |
> |
* |
275 |
> |
* @return true if successful |
276 |
|
*/ |
277 |
< |
static void rethrowException(Throwable ex) { |
278 |
< |
if (ex != null) |
279 |
< |
_unsafe.throwException(ex); |
277 |
> |
final boolean trySetSignal() { |
278 |
> |
int s = status; |
279 |
> |
return s >= 0 && U.compareAndSwapInt(this, STATUS, s, s | SIGNAL); |
280 |
|
} |
281 |
|
|
176 |
– |
// Setting completion status |
177 |
– |
|
282 |
|
/** |
283 |
< |
* Mark completion and wake up threads waiting to join this task. |
284 |
< |
* @param completion one of NORMAL, CANCELLED, EXCEPTIONAL |
283 |
> |
* Blocks a non-worker-thread until completion. |
284 |
> |
* @return status upon completion |
285 |
|
*/ |
286 |
< |
final void setCompletion(int completion) { |
287 |
< |
ForkJoinPool pool = getPool(); |
288 |
< |
if (pool != null) { |
289 |
< |
int s; // Clear signal bits while setting completion status |
290 |
< |
do;while ((s = status) >= 0 && !casStatus(s, completion)); |
291 |
< |
|
292 |
< |
if ((s & SIGNAL_MASK) != 0) { |
293 |
< |
if ((s &= INTERNAL_SIGNAL_MASK) != 0) |
294 |
< |
pool.updateRunningCount(s); |
295 |
< |
synchronized(this) { notifyAll(); } |
286 |
> |
private int externalAwaitDone() { |
287 |
> |
int s; |
288 |
> |
ForkJoinPool.externalHelpJoin(this); |
289 |
> |
boolean interrupted = false; |
290 |
> |
while ((s = status) >= 0) { |
291 |
> |
if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) { |
292 |
> |
synchronized (this) { |
293 |
> |
if (status >= 0) { |
294 |
> |
try { |
295 |
> |
wait(); |
296 |
> |
} catch (InterruptedException ie) { |
297 |
> |
interrupted = true; |
298 |
> |
} |
299 |
> |
} |
300 |
> |
else |
301 |
> |
notifyAll(); |
302 |
> |
} |
303 |
|
} |
304 |
|
} |
305 |
< |
else |
306 |
< |
externallySetCompletion(completion); |
305 |
> |
if (interrupted) |
306 |
> |
Thread.currentThread().interrupt(); |
307 |
> |
return s; |
308 |
|
} |
309 |
|
|
310 |
|
/** |
311 |
< |
* Version of setCompletion for non-FJ threads. Leaves signal |
200 |
< |
* bits for unblocked threads to adjust, and always notifies. |
311 |
> |
* Blocks a non-worker-thread until completion or interruption. |
312 |
|
*/ |
313 |
< |
private void externallySetCompletion(int completion) { |
313 |
> |
private int externalInterruptibleAwaitDone() throws InterruptedException { |
314 |
|
int s; |
315 |
< |
do;while ((s = status) >= 0 && |
316 |
< |
!casStatus(s, (s & SIGNAL_MASK) | completion)); |
317 |
< |
synchronized(this) { notifyAll(); } |
318 |
< |
} |
319 |
< |
|
320 |
< |
/** |
321 |
< |
* Sets status to indicate normal completion |
322 |
< |
*/ |
323 |
< |
final void setNormalCompletion() { |
324 |
< |
// Try typical fast case -- single CAS, no signal, not already done. |
325 |
< |
// Manually expand casStatus to improve chances of inlining it |
326 |
< |
if (!_unsafe.compareAndSwapInt(this, statusOffset, 0, NORMAL)) |
327 |
< |
setCompletion(NORMAL); |
315 |
> |
if (Thread.interrupted()) |
316 |
> |
throw new InterruptedException(); |
317 |
> |
ForkJoinPool.externalHelpJoin(this); |
318 |
> |
while ((s = status) >= 0) { |
319 |
> |
if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) { |
320 |
> |
synchronized (this) { |
321 |
> |
if (status >= 0) |
322 |
> |
wait(); |
323 |
> |
else |
324 |
> |
notifyAll(); |
325 |
> |
} |
326 |
> |
} |
327 |
> |
} |
328 |
> |
return s; |
329 |
|
} |
330 |
|
|
219 |
– |
// internal waiting and notification |
331 |
|
|
332 |
|
/** |
333 |
< |
* Performs the actual monitor wait for awaitDone |
333 |
> |
* Implementation for join, get, quietlyJoin. Directly handles |
334 |
> |
* only cases of already-completed, external wait, and |
335 |
> |
* unfork+exec. Others are relayed to ForkJoinPool.awaitJoin. |
336 |
> |
* |
337 |
> |
* @return status upon completion |
338 |
|
*/ |
339 |
< |
private void doAwaitDone() { |
340 |
< |
// Minimize lock bias and in/de-flation effects by maximizing |
341 |
< |
// chances of waiting inside sync |
342 |
< |
try { |
343 |
< |
while (status >= 0) |
344 |
< |
synchronized(this) { if (status >= 0) wait(); } |
345 |
< |
} catch (InterruptedException ie) { |
346 |
< |
onInterruptedWait(); |
232 |
< |
} |
339 |
> |
private int doJoin() { |
340 |
> |
int s; Thread t; ForkJoinWorkerThread wt; ForkJoinPool.WorkQueue w; |
341 |
> |
return (s = status) < 0 ? s : |
342 |
> |
((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
343 |
> |
(w = (wt = (ForkJoinWorkerThread)t).workQueue). |
344 |
> |
tryUnpush(this) && (s = doExec()) < 0 ? s : |
345 |
> |
wt.pool.awaitJoin(w, this) : |
346 |
> |
externalAwaitDone(); |
347 |
|
} |
348 |
|
|
349 |
|
/** |
350 |
< |
* Performs the actual monitor wait for awaitDone |
350 |
> |
* Implementation for invoke, quietlyInvoke. |
351 |
> |
* |
352 |
> |
* @return status upon completion |
353 |
|
*/ |
354 |
< |
private void doAwaitDone(long startTime, long nanos) { |
355 |
< |
synchronized(this) { |
356 |
< |
try { |
357 |
< |
while (status >= 0) { |
358 |
< |
long nt = nanos - System.nanoTime() - startTime; |
359 |
< |
if (nt <= 0) |
244 |
< |
break; |
245 |
< |
wait(nt / 1000000, (int)(nt % 1000000)); |
246 |
< |
} |
247 |
< |
} catch (InterruptedException ie) { |
248 |
< |
onInterruptedWait(); |
249 |
< |
} |
250 |
< |
} |
354 |
> |
private int doInvoke() { |
355 |
> |
int s; Thread t; ForkJoinWorkerThread wt; |
356 |
> |
return (s = doExec()) < 0 ? s : |
357 |
> |
((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
358 |
> |
(wt = (ForkJoinWorkerThread)t).pool.awaitJoin(wt.workQueue, this) : |
359 |
> |
externalAwaitDone(); |
360 |
|
} |
361 |
|
|
362 |
< |
// Awaiting completion |
362 |
> |
// Exception table support |
363 |
|
|
364 |
|
/** |
365 |
< |
* Sets status to indicate there is joiner, then waits for join, |
366 |
< |
* surrounded with pool notifications. |
367 |
< |
* @return status upon exit |
365 |
> |
* Table of exceptions thrown by tasks, to enable reporting by |
366 |
> |
* callers. Because exceptions are rare, we don't directly keep |
367 |
> |
* them with task objects, but instead use a weak ref table. Note |
368 |
> |
* that cancellation exceptions don't appear in the table, but are |
369 |
> |
* instead recorded as status values. |
370 |
> |
* |
371 |
> |
* Note: These statics are initialized below in static block. |
372 |
|
*/ |
373 |
< |
private int awaitDone(ForkJoinWorkerThread w, boolean maintainParallelism) { |
374 |
< |
ForkJoinPool pool = w == null? null : w.pool; |
375 |
< |
int s; |
376 |
< |
while ((s = status) >= 0) { |
377 |
< |
if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) { |
378 |
< |
if (pool == null || !pool.preJoin(this, maintainParallelism)) |
379 |
< |
doAwaitDone(); |
380 |
< |
if (((s = status) & INTERNAL_SIGNAL_MASK) != 0) |
381 |
< |
adjustPoolCountsOnUnblock(pool); |
382 |
< |
break; |
383 |
< |
} |
373 |
> |
private static final ExceptionNode[] exceptionTable; |
374 |
> |
private static final ReentrantLock exceptionTableLock; |
375 |
> |
private static final ReferenceQueue<Object> exceptionTableRefQueue; |
376 |
> |
|
377 |
> |
/** |
378 |
> |
* Fixed capacity for exceptionTable. |
379 |
> |
*/ |
380 |
> |
private static final int EXCEPTION_MAP_CAPACITY = 32; |
381 |
> |
|
382 |
> |
/** |
383 |
> |
* Key-value nodes for exception table. The chained hash table |
384 |
> |
* uses identity comparisons, full locking, and weak references |
385 |
> |
* for keys. The table has a fixed capacity because it only |
386 |
> |
* maintains task exceptions long enough for joiners to access |
387 |
> |
* them, so should never become very large for sustained |
388 |
> |
* periods. However, since we do not know when the last joiner |
389 |
> |
* completes, we must use weak references and expunge them. We do |
390 |
> |
* so on each operation (hence full locking). Also, some thread in |
391 |
> |
* any ForkJoinPool will call helpExpungeStaleExceptions when its |
392 |
> |
* pool becomes isQuiescent. |
393 |
> |
*/ |
394 |
> |
static final class ExceptionNode extends WeakReference<ForkJoinTask<?>> { |
395 |
> |
final Throwable ex; |
396 |
> |
ExceptionNode next; |
397 |
> |
final long thrower; // use id not ref to avoid weak cycles |
398 |
> |
ExceptionNode(ForkJoinTask<?> task, Throwable ex, ExceptionNode next) { |
399 |
> |
super(task, exceptionTableRefQueue); |
400 |
> |
this.ex = ex; |
401 |
> |
this.next = next; |
402 |
> |
this.thrower = Thread.currentThread().getId(); |
403 |
|
} |
272 |
– |
return s; |
404 |
|
} |
405 |
|
|
406 |
|
/** |
407 |
< |
* Timed version of awaitDone |
408 |
< |
* @return status upon exit |
407 |
> |
* Records exception and sets status. |
408 |
> |
* |
409 |
> |
* @return status on exit |
410 |
|
*/ |
411 |
< |
private int awaitDone(ForkJoinWorkerThread w, long nanos) { |
280 |
< |
ForkJoinPool pool = w == null? null : w.pool; |
411 |
> |
final int recordExceptionalCompletion(Throwable ex) { |
412 |
|
int s; |
413 |
< |
while ((s = status) >= 0) { |
414 |
< |
if (casStatus(s, pool == null? s|EXTERNAL_SIGNAL : s+1)) { |
415 |
< |
long startTime = System.nanoTime(); |
416 |
< |
if (pool == null || !pool.preJoin(this, false)) |
417 |
< |
doAwaitDone(startTime, nanos); |
418 |
< |
if ((s = status) >= 0) { |
419 |
< |
adjustPoolCountsOnCancelledWait(pool); |
420 |
< |
s = status; |
413 |
> |
if ((s = status) >= 0) { |
414 |
> |
int h = System.identityHashCode(this); |
415 |
> |
final ReentrantLock lock = exceptionTableLock; |
416 |
> |
lock.lock(); |
417 |
> |
try { |
418 |
> |
expungeStaleExceptions(); |
419 |
> |
ExceptionNode[] t = exceptionTable; |
420 |
> |
int i = h & (t.length - 1); |
421 |
> |
for (ExceptionNode e = t[i]; ; e = e.next) { |
422 |
> |
if (e == null) { |
423 |
> |
t[i] = new ExceptionNode(this, ex, t[i]); |
424 |
> |
break; |
425 |
> |
} |
426 |
> |
if (e.get() == this) // already present |
427 |
> |
break; |
428 |
|
} |
429 |
< |
if (s < 0 && (s & INTERNAL_SIGNAL_MASK) != 0) |
430 |
< |
adjustPoolCountsOnUnblock(pool); |
293 |
< |
break; |
429 |
> |
} finally { |
430 |
> |
lock.unlock(); |
431 |
|
} |
432 |
+ |
s = setCompletion(EXCEPTIONAL); |
433 |
|
} |
434 |
|
return s; |
435 |
|
} |
436 |
|
|
437 |
|
/** |
438 |
< |
* Notify pool that thread is unblocked. Called by signalled |
439 |
< |
* threads when woken by non-FJ threads (which is atypical). |
440 |
< |
*/ |
303 |
< |
private void adjustPoolCountsOnUnblock(ForkJoinPool pool) { |
304 |
< |
int s; |
305 |
< |
do;while ((s = status) < 0 && !casStatus(s, s & COMPLETION_MASK)); |
306 |
< |
if (pool != null && (s &= INTERNAL_SIGNAL_MASK) != 0) |
307 |
< |
pool.updateRunningCount(s); |
308 |
< |
} |
309 |
< |
|
310 |
< |
/** |
311 |
< |
* Notify pool to adjust counts on cancelled or timed out wait |
438 |
> |
* Records exception and possibly propagates. |
439 |
> |
* |
440 |
> |
* @return status on exit |
441 |
|
*/ |
442 |
< |
private void adjustPoolCountsOnCancelledWait(ForkJoinPool pool) { |
443 |
< |
if (pool != null) { |
444 |
< |
int s; |
445 |
< |
while ((s = status) >= 0 && (s & INTERNAL_SIGNAL_MASK) != 0) { |
446 |
< |
if (casStatus(s, s - 1)) { |
318 |
< |
pool.updateRunningCount(1); |
319 |
< |
break; |
320 |
< |
} |
321 |
< |
} |
322 |
< |
} |
442 |
> |
private int setExceptionalCompletion(Throwable ex) { |
443 |
> |
int s = recordExceptionalCompletion(ex); |
444 |
> |
if ((s & DONE_MASK) == EXCEPTIONAL) |
445 |
> |
internalPropagateException(ex); |
446 |
> |
return s; |
447 |
|
} |
448 |
|
|
449 |
|
/** |
450 |
< |
* Handle interruptions during waits. |
450 |
> |
* Hook for exception propagation support for tasks with completers. |
451 |
|
*/ |
452 |
< |
private void onInterruptedWait() { |
329 |
< |
ForkJoinWorkerThread w = getWorker(); |
330 |
< |
if (w == null) |
331 |
< |
Thread.currentThread().interrupt(); // re-interrupt |
332 |
< |
else if (w.isTerminating()) |
333 |
< |
cancelIgnoringExceptions(); |
334 |
< |
// else if FJworker, ignore interrupt |
335 |
< |
} |
336 |
< |
|
337 |
< |
// Recording and reporting exceptions |
338 |
< |
|
339 |
< |
private void setDoneExceptionally(Throwable rex) { |
340 |
< |
exceptionMap.put(this, rex); |
341 |
< |
setCompletion(EXCEPTIONAL); |
452 |
> |
void internalPropagateException(Throwable ex) { |
453 |
|
} |
454 |
|
|
455 |
|
/** |
456 |
< |
* Throws the exception associated with status s; |
457 |
< |
* @throws the exception |
456 |
> |
* Cancels, ignoring any exceptions thrown by cancel. Used during |
457 |
> |
* worker and pool shutdown. Cancel is spec'ed not to throw any |
458 |
> |
* exceptions, but if it does anyway, we have no recourse during |
459 |
> |
* shutdown, so guard against this case. |
460 |
|
*/ |
461 |
< |
private void reportException(int s) { |
462 |
< |
if ((s &= COMPLETION_MASK) < NORMAL) { |
463 |
< |
if (s == CANCELLED) |
464 |
< |
throw new CancellationException(); |
465 |
< |
else |
466 |
< |
rethrowException(exceptionMap.get(this)); |
461 |
> |
static final void cancelIgnoringExceptions(ForkJoinTask<?> t) { |
462 |
> |
if (t != null && t.status >= 0) { |
463 |
> |
try { |
464 |
> |
t.cancel(false); |
465 |
> |
} catch (Throwable ignore) { |
466 |
> |
} |
467 |
|
} |
468 |
|
} |
469 |
|
|
470 |
|
/** |
471 |
< |
* Returns result or throws exception using j.u.c.Future conventions |
359 |
< |
* Only call when isDone known to be true. |
471 |
> |
* Removes exception node and clears status |
472 |
|
*/ |
473 |
< |
private V reportFutureResult() |
474 |
< |
throws ExecutionException, InterruptedException { |
475 |
< |
int s = status & COMPLETION_MASK; |
476 |
< |
if (s < NORMAL) { |
477 |
< |
Throwable ex; |
478 |
< |
if (s == CANCELLED) |
479 |
< |
throw new CancellationException(); |
480 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
481 |
< |
throw new ExecutionException(ex); |
482 |
< |
if (Thread.interrupted()) |
483 |
< |
throw new InterruptedException(); |
473 |
> |
private void clearExceptionalCompletion() { |
474 |
> |
int h = System.identityHashCode(this); |
475 |
> |
final ReentrantLock lock = exceptionTableLock; |
476 |
> |
lock.lock(); |
477 |
> |
try { |
478 |
> |
ExceptionNode[] t = exceptionTable; |
479 |
> |
int i = h & (t.length - 1); |
480 |
> |
ExceptionNode e = t[i]; |
481 |
> |
ExceptionNode pred = null; |
482 |
> |
while (e != null) { |
483 |
> |
ExceptionNode next = e.next; |
484 |
> |
if (e.get() == this) { |
485 |
> |
if (pred == null) |
486 |
> |
t[i] = next; |
487 |
> |
else |
488 |
> |
pred.next = next; |
489 |
> |
break; |
490 |
> |
} |
491 |
> |
pred = e; |
492 |
> |
e = next; |
493 |
> |
} |
494 |
> |
expungeStaleExceptions(); |
495 |
> |
status = 0; |
496 |
> |
} finally { |
497 |
> |
lock.unlock(); |
498 |
|
} |
373 |
– |
return getRawResult(); |
499 |
|
} |
500 |
|
|
501 |
|
/** |
502 |
< |
* Returns result or throws exception using j.u.c.Future conventions |
503 |
< |
* with timeouts |
502 |
> |
* Returns a rethrowable exception for the given task, if |
503 |
> |
* available. To provide accurate stack traces, if the exception |
504 |
> |
* was not thrown by the current thread, we try to create a new |
505 |
> |
* exception of the same type as the one thrown, but with the |
506 |
> |
* recorded exception as its cause. If there is no such |
507 |
> |
* constructor, we instead try to use a no-arg constructor, |
508 |
> |
* followed by initCause, to the same effect. If none of these |
509 |
> |
* apply, or any fail due to other exceptions, we return the |
510 |
> |
* recorded exception, which is still correct, although it may |
511 |
> |
* contain a misleading stack trace. |
512 |
> |
* |
513 |
> |
* @return the exception, or null if none |
514 |
|
*/ |
515 |
< |
private V reportTimedFutureResult() |
516 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
515 |
> |
private Throwable getThrowableException() { |
516 |
> |
if ((status & DONE_MASK) != EXCEPTIONAL) |
517 |
> |
return null; |
518 |
> |
int h = System.identityHashCode(this); |
519 |
> |
ExceptionNode e; |
520 |
> |
final ReentrantLock lock = exceptionTableLock; |
521 |
> |
lock.lock(); |
522 |
> |
try { |
523 |
> |
expungeStaleExceptions(); |
524 |
> |
ExceptionNode[] t = exceptionTable; |
525 |
> |
e = t[h & (t.length - 1)]; |
526 |
> |
while (e != null && e.get() != this) |
527 |
> |
e = e.next; |
528 |
> |
} finally { |
529 |
> |
lock.unlock(); |
530 |
> |
} |
531 |
|
Throwable ex; |
532 |
< |
int s = status & COMPLETION_MASK; |
533 |
< |
if (s == NORMAL) |
534 |
< |
return getRawResult(); |
535 |
< |
if (s == CANCELLED) |
536 |
< |
throw new CancellationException(); |
537 |
< |
if (s == EXCEPTIONAL && (ex = exceptionMap.get(this)) != null) |
538 |
< |
throw new ExecutionException(ex); |
539 |
< |
if (Thread.interrupted()) |
540 |
< |
throw new InterruptedException(); |
541 |
< |
throw new TimeoutException(); |
532 |
> |
if (e == null || (ex = e.ex) == null) |
533 |
> |
return null; |
534 |
> |
if (false && e.thrower != Thread.currentThread().getId()) { |
535 |
> |
Class<? extends Throwable> ec = ex.getClass(); |
536 |
> |
try { |
537 |
> |
Constructor<?> noArgCtor = null; |
538 |
> |
Constructor<?>[] cs = ec.getConstructors();// public ctors only |
539 |
> |
for (int i = 0; i < cs.length; ++i) { |
540 |
> |
Constructor<?> c = cs[i]; |
541 |
> |
Class<?>[] ps = c.getParameterTypes(); |
542 |
> |
if (ps.length == 0) |
543 |
> |
noArgCtor = c; |
544 |
> |
else if (ps.length == 1 && ps[0] == Throwable.class) |
545 |
> |
return (Throwable)(c.newInstance(ex)); |
546 |
> |
} |
547 |
> |
if (noArgCtor != null) { |
548 |
> |
Throwable wx = (Throwable)(noArgCtor.newInstance()); |
549 |
> |
wx.initCause(ex); |
550 |
> |
return wx; |
551 |
> |
} |
552 |
> |
} catch (Exception ignore) { |
553 |
> |
} |
554 |
> |
} |
555 |
> |
return ex; |
556 |
|
} |
557 |
|
|
395 |
– |
// internal execution methods |
396 |
– |
|
558 |
|
/** |
559 |
< |
* Calls exec, recording completion, and rethrowing exception if |
399 |
< |
* encountered. Caller should normally check status before calling |
400 |
< |
* @return true if completed normally |
559 |
> |
* Poll stale refs and remove them. Call only while holding lock. |
560 |
|
*/ |
561 |
< |
private boolean tryExec() { |
562 |
< |
try { // try block must contain only call to exec |
563 |
< |
if (!exec()) |
564 |
< |
return false; |
565 |
< |
} catch (Throwable rex) { |
566 |
< |
setDoneExceptionally(rex); |
567 |
< |
rethrowException(rex); |
568 |
< |
return false; // not reached |
561 |
> |
private static void expungeStaleExceptions() { |
562 |
> |
for (Object x; (x = exceptionTableRefQueue.poll()) != null;) { |
563 |
> |
if (x instanceof ExceptionNode) { |
564 |
> |
ForkJoinTask<?> key = ((ExceptionNode)x).get(); |
565 |
> |
ExceptionNode[] t = exceptionTable; |
566 |
> |
int i = System.identityHashCode(key) & (t.length - 1); |
567 |
> |
ExceptionNode e = t[i]; |
568 |
> |
ExceptionNode pred = null; |
569 |
> |
while (e != null) { |
570 |
> |
ExceptionNode next = e.next; |
571 |
> |
if (e == x) { |
572 |
> |
if (pred == null) |
573 |
> |
t[i] = next; |
574 |
> |
else |
575 |
> |
pred.next = next; |
576 |
> |
break; |
577 |
> |
} |
578 |
> |
pred = e; |
579 |
> |
e = next; |
580 |
> |
} |
581 |
> |
} |
582 |
|
} |
411 |
– |
setNormalCompletion(); |
412 |
– |
return true; |
583 |
|
} |
584 |
|
|
585 |
|
/** |
586 |
< |
* Main execution method used by worker threads. Invokes |
587 |
< |
* base computation unless already complete |
586 |
> |
* If lock is available, poll stale refs and remove them. |
587 |
> |
* Called from ForkJoinPool when pools become quiescent. |
588 |
|
*/ |
589 |
< |
final void quietlyExec() { |
590 |
< |
if (status >= 0) { |
589 |
> |
static final void helpExpungeStaleExceptions() { |
590 |
> |
final ReentrantLock lock = exceptionTableLock; |
591 |
> |
if (lock.tryLock()) { |
592 |
|
try { |
593 |
< |
if (!exec()) |
594 |
< |
return; |
595 |
< |
} catch(Throwable rex) { |
425 |
< |
setDoneExceptionally(rex); |
426 |
< |
return; |
593 |
> |
expungeStaleExceptions(); |
594 |
> |
} finally { |
595 |
> |
lock.unlock(); |
596 |
|
} |
428 |
– |
setNormalCompletion(); |
597 |
|
} |
598 |
|
} |
599 |
|
|
600 |
|
/** |
601 |
< |
* Calls exec, recording but not rethrowing exception |
434 |
< |
* Caller should normally check status before calling |
435 |
< |
* @return true if completed normally |
601 |
> |
* A version of "sneaky throw" to relay exceptions |
602 |
|
*/ |
603 |
< |
private boolean tryQuietlyInvoke() { |
604 |
< |
try { |
605 |
< |
if (!exec()) |
606 |
< |
return false; |
607 |
< |
} catch (Throwable rex) { |
608 |
< |
setDoneExceptionally(rex); |
609 |
< |
return false; |
603 |
> |
static void rethrow(final Throwable ex) { |
604 |
> |
if (ex != null) { |
605 |
> |
if (ex instanceof Error) |
606 |
> |
throw (Error)ex; |
607 |
> |
if (ex instanceof RuntimeException) |
608 |
> |
throw (RuntimeException)ex; |
609 |
> |
ForkJoinTask.<RuntimeException>uncheckedThrow(ex); |
610 |
|
} |
445 |
– |
setNormalCompletion(); |
446 |
– |
return true; |
611 |
|
} |
612 |
|
|
613 |
|
/** |
614 |
< |
* Cancel, ignoring any exceptions it throws |
614 |
> |
* The sneaky part of sneaky throw, relying on generics |
615 |
> |
* limitations to evade compiler complaints about rethrowing |
616 |
> |
* unchecked exceptions |
617 |
|
*/ |
618 |
< |
final void cancelIgnoringExceptions() { |
619 |
< |
try { |
620 |
< |
cancel(false); |
621 |
< |
} catch(Throwable ignore) { |
456 |
< |
} |
618 |
> |
@SuppressWarnings("unchecked") static <T extends Throwable> |
619 |
> |
void uncheckedThrow(Throwable t) throws T { |
620 |
> |
if (t != null) |
621 |
> |
throw (T)t; // rely on vacuous cast |
622 |
|
} |
623 |
|
|
624 |
|
/** |
625 |
< |
* Main implementation of helpJoin |
625 |
> |
* Throws exception, if any, associated with the given status. |
626 |
|
*/ |
627 |
< |
private int busyJoin(ForkJoinWorkerThread w) { |
628 |
< |
int s; |
629 |
< |
ForkJoinTask<?> t; |
630 |
< |
while ((s = status) >= 0 && (t = w.scanWhileJoining(this)) != null) |
631 |
< |
t.quietlyExec(); |
467 |
< |
return (s >= 0)? awaitDone(w, false) : s; // block if no work |
627 |
> |
private void reportException(int s) { |
628 |
> |
if (s == CANCELLED) |
629 |
> |
throw new CancellationException(); |
630 |
> |
if (s == EXCEPTIONAL) |
631 |
> |
rethrow(getThrowableException()); |
632 |
|
} |
633 |
|
|
634 |
|
// public methods |
635 |
|
|
636 |
|
/** |
637 |
< |
* Arranges to asynchronously execute this task. While it is not |
638 |
< |
* necessarily enforced, it is a usage error to fork a task more |
639 |
< |
* than once unless it has completed and been reinitialized. This |
640 |
< |
* method may be invoked only from within ForkJoinTask |
641 |
< |
* computations. Attempts to invoke in other contexts result in |
642 |
< |
* exceptions or errors possibly including ClassCastException. |
643 |
< |
*/ |
644 |
< |
public final void fork() { |
645 |
< |
((ForkJoinWorkerThread)(Thread.currentThread())).pushTask(this); |
637 |
> |
* Arranges to asynchronously execute this task in the pool the |
638 |
> |
* current task is running in, if applicable, or using the {@link |
639 |
> |
* ForkJoinPool#commonPool()} if not {@link #inForkJoinPool}. While |
640 |
> |
* it is not necessarily enforced, it is a usage error to fork a |
641 |
> |
* task more than once unless it has completed and been |
642 |
> |
* reinitialized. Subsequent modifications to the state of this |
643 |
> |
* task or any data it operates on are not necessarily |
644 |
> |
* consistently observable by any thread other than the one |
645 |
> |
* executing it unless preceded by a call to {@link #join} or |
646 |
> |
* related methods, or a call to {@link #isDone} returning {@code |
647 |
> |
* true}. |
648 |
> |
* |
649 |
> |
* @return {@code this}, to simplify usage |
650 |
> |
*/ |
651 |
> |
public final ForkJoinTask<V> fork() { |
652 |
> |
Thread t; |
653 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
654 |
> |
((ForkJoinWorkerThread)t).workQueue.push(this); |
655 |
> |
else |
656 |
> |
ForkJoinPool.common.externalPush(this); |
657 |
> |
return this; |
658 |
|
} |
659 |
|
|
660 |
|
/** |
661 |
< |
* Returns the result of the computation when it is ready. |
662 |
< |
* This method differs from <code>get</code> in that abnormal |
663 |
< |
* completion results in RuntimeExceptions or Errors, not |
664 |
< |
* ExecutionExceptions. |
661 |
> |
* Returns the result of the computation when it {@link #isDone is |
662 |
> |
* done}. This method differs from {@link #get()} in that |
663 |
> |
* abnormal completion results in {@code RuntimeException} or |
664 |
> |
* {@code Error}, not {@code ExecutionException}, and that |
665 |
> |
* interrupts of the calling thread do <em>not</em> cause the |
666 |
> |
* method to abruptly return by throwing {@code |
667 |
> |
* InterruptedException}. |
668 |
|
* |
669 |
|
* @return the computed result |
670 |
|
*/ |
671 |
|
public final V join() { |
672 |
< |
ForkJoinWorkerThread w = getWorker(); |
673 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryExec()) |
674 |
< |
reportException(awaitDone(w, true)); |
672 |
> |
int s; |
673 |
> |
if ((s = doJoin() & DONE_MASK) != NORMAL) |
674 |
> |
reportException(s); |
675 |
|
return getRawResult(); |
676 |
|
} |
677 |
|
|
678 |
|
/** |
679 |
|
* Commences performing this task, awaits its completion if |
680 |
< |
* necessary, and return its result. |
681 |
< |
* @throws Throwable (a RuntimeException, Error, or unchecked |
682 |
< |
* exception) if the underlying computation did so. |
680 |
> |
* necessary, and returns its result, or throws an (unchecked) |
681 |
> |
* {@code RuntimeException} or {@code Error} if the underlying |
682 |
> |
* computation did so. |
683 |
> |
* |
684 |
|
* @return the computed result |
685 |
|
*/ |
686 |
|
public final V invoke() { |
687 |
< |
if (status >= 0 && tryExec()) |
688 |
< |
return getRawResult(); |
689 |
< |
else |
690 |
< |
return join(); |
687 |
> |
int s; |
688 |
> |
if ((s = doInvoke() & DONE_MASK) != NORMAL) |
689 |
> |
reportException(s); |
690 |
> |
return getRawResult(); |
691 |
|
} |
692 |
|
|
693 |
|
/** |
694 |
< |
* Forks both tasks, returning when <code>isDone</code> holds for |
695 |
< |
* both of them or an exception is encountered. This method may be |
696 |
< |
* invoked only from within ForkJoinTask computations. Attempts to |
697 |
< |
* invoke in other contexts result in exceptions or errors |
698 |
< |
* possibly including ClassCastException. |
699 |
< |
* @param t1 one task |
700 |
< |
* @param t2 the other task |
701 |
< |
* @throws NullPointerException if t1 or t2 are null |
702 |
< |
* @throws RuntimeException or Error if either task did so. |
694 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
695 |
> |
* each task or an (unchecked) exception is encountered, in which |
696 |
> |
* case the exception is rethrown. If more than one task |
697 |
> |
* encounters an exception, then this method throws any one of |
698 |
> |
* these exceptions. If any task encounters an exception, the |
699 |
> |
* other may be cancelled. However, the execution status of |
700 |
> |
* individual tasks is not guaranteed upon exceptional return. The |
701 |
> |
* status of each task may be obtained using {@link |
702 |
> |
* #getException()} and related methods to check if they have been |
703 |
> |
* cancelled, completed normally or exceptionally, or left |
704 |
> |
* unprocessed. |
705 |
> |
* |
706 |
> |
* @param t1 the first task |
707 |
> |
* @param t2 the second task |
708 |
> |
* @throws NullPointerException if any task is null |
709 |
|
*/ |
710 |
< |
public static void invokeAll(ForkJoinTask<?>t1, ForkJoinTask<?> t2) { |
710 |
> |
public static void invokeAll(ForkJoinTask<?> t1, ForkJoinTask<?> t2) { |
711 |
> |
int s1, s2; |
712 |
|
t2.fork(); |
713 |
< |
t1.invoke(); |
714 |
< |
t2.join(); |
713 |
> |
if ((s1 = t1.doInvoke() & DONE_MASK) != NORMAL) |
714 |
> |
t1.reportException(s1); |
715 |
> |
if ((s2 = t2.doJoin() & DONE_MASK) != NORMAL) |
716 |
> |
t2.reportException(s2); |
717 |
|
} |
718 |
|
|
719 |
|
/** |
720 |
< |
* Forks the given tasks, returning when <code>isDone</code> holds |
721 |
< |
* for all of them. If any task encounters an exception, others |
722 |
< |
* may be cancelled. This method may be invoked only from within |
723 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
724 |
< |
* result in exceptions or errors possibly including ClassCastException. |
725 |
< |
* @param tasks the array of tasks |
726 |
< |
* @throws NullPointerException if tasks or any element are null. |
727 |
< |
* @throws RuntimeException or Error if any task did so. |
720 |
> |
* Forks the given tasks, returning when {@code isDone} holds for |
721 |
> |
* each task or an (unchecked) exception is encountered, in which |
722 |
> |
* case the exception is rethrown. If more than one task |
723 |
> |
* encounters an exception, then this method throws any one of |
724 |
> |
* these exceptions. If any task encounters an exception, others |
725 |
> |
* may be cancelled. However, the execution status of individual |
726 |
> |
* tasks is not guaranteed upon exceptional return. The status of |
727 |
> |
* each task may be obtained using {@link #getException()} and |
728 |
> |
* related methods to check if they have been cancelled, completed |
729 |
> |
* normally or exceptionally, or left unprocessed. |
730 |
> |
* |
731 |
> |
* @param tasks the tasks |
732 |
> |
* @throws NullPointerException if any task is null |
733 |
|
*/ |
734 |
|
public static void invokeAll(ForkJoinTask<?>... tasks) { |
735 |
|
Throwable ex = null; |
742 |
|
} |
743 |
|
else if (i != 0) |
744 |
|
t.fork(); |
745 |
< |
else { |
746 |
< |
t.quietlyInvoke(); |
553 |
< |
if (ex == null) |
554 |
< |
ex = t.getException(); |
555 |
< |
} |
745 |
> |
else if (t.doInvoke() < NORMAL && ex == null) |
746 |
> |
ex = t.getException(); |
747 |
|
} |
748 |
|
for (int i = 1; i <= last; ++i) { |
749 |
|
ForkJoinTask<?> t = tasks[i]; |
750 |
|
if (t != null) { |
751 |
|
if (ex != null) |
752 |
|
t.cancel(false); |
753 |
< |
else { |
754 |
< |
t.quietlyJoin(); |
564 |
< |
if (ex == null) |
565 |
< |
ex = t.getException(); |
566 |
< |
} |
753 |
> |
else if (t.doJoin() < NORMAL) |
754 |
> |
ex = t.getException(); |
755 |
|
} |
756 |
|
} |
757 |
|
if (ex != null) |
758 |
< |
rethrowException(ex); |
758 |
> |
rethrow(ex); |
759 |
|
} |
760 |
|
|
761 |
|
/** |
762 |
< |
* Forks all tasks in the collection, returning when |
763 |
< |
* <code>isDone</code> holds for all of them. If any task |
764 |
< |
* encounters an exception, others may be cancelled. This method |
765 |
< |
* may be invoked only from within ForkJoinTask |
766 |
< |
* computations. Attempts to invoke in other contexts resul!t in |
767 |
< |
* exceptions or errors possibly including ClassCastException. |
762 |
> |
* Forks all tasks in the specified collection, returning when |
763 |
> |
* {@code isDone} holds for each task or an (unchecked) exception |
764 |
> |
* is encountered, in which case the exception is rethrown. If |
765 |
> |
* more than one task encounters an exception, then this method |
766 |
> |
* throws any one of these exceptions. If any task encounters an |
767 |
> |
* exception, others may be cancelled. However, the execution |
768 |
> |
* status of individual tasks is not guaranteed upon exceptional |
769 |
> |
* return. The status of each task may be obtained using {@link |
770 |
> |
* #getException()} and related methods to check if they have been |
771 |
> |
* cancelled, completed normally or exceptionally, or left |
772 |
> |
* unprocessed. |
773 |
> |
* |
774 |
|
* @param tasks the collection of tasks |
775 |
< |
* @throws NullPointerException if tasks or any element are null. |
776 |
< |
* @throws RuntimeException or Error if any task did so. |
775 |
> |
* @return the tasks argument, to simplify usage |
776 |
> |
* @throws NullPointerException if tasks or any element are null |
777 |
|
*/ |
778 |
< |
public static void invokeAll(Collection<? extends ForkJoinTask<?>> tasks) { |
779 |
< |
if (!(tasks instanceof List)) { |
780 |
< |
invokeAll(tasks.toArray(new ForkJoinTask[tasks.size()])); |
781 |
< |
return; |
778 |
> |
public static <T extends ForkJoinTask<?>> Collection<T> invokeAll(Collection<T> tasks) { |
779 |
> |
if (!(tasks instanceof RandomAccess) || !(tasks instanceof List<?>)) { |
780 |
> |
invokeAll(tasks.toArray(new ForkJoinTask<?>[tasks.size()])); |
781 |
> |
return tasks; |
782 |
|
} |
783 |
+ |
@SuppressWarnings("unchecked") |
784 |
|
List<? extends ForkJoinTask<?>> ts = |
785 |
< |
(List<? extends ForkJoinTask<?>>)tasks; |
785 |
> |
(List<? extends ForkJoinTask<?>>) tasks; |
786 |
|
Throwable ex = null; |
787 |
|
int last = ts.size() - 1; |
788 |
|
for (int i = last; i >= 0; --i) { |
793 |
|
} |
794 |
|
else if (i != 0) |
795 |
|
t.fork(); |
796 |
< |
else { |
797 |
< |
t.quietlyInvoke(); |
603 |
< |
if (ex == null) |
604 |
< |
ex = t.getException(); |
605 |
< |
} |
796 |
> |
else if (t.doInvoke() < NORMAL && ex == null) |
797 |
> |
ex = t.getException(); |
798 |
|
} |
799 |
|
for (int i = 1; i <= last; ++i) { |
800 |
|
ForkJoinTask<?> t = ts.get(i); |
801 |
|
if (t != null) { |
802 |
|
if (ex != null) |
803 |
|
t.cancel(false); |
804 |
< |
else { |
805 |
< |
t.quietlyJoin(); |
614 |
< |
if (ex == null) |
615 |
< |
ex = t.getException(); |
616 |
< |
} |
804 |
> |
else if (t.doJoin() < NORMAL) |
805 |
> |
ex = t.getException(); |
806 |
|
} |
807 |
|
} |
808 |
|
if (ex != null) |
809 |
< |
rethrowException(ex); |
809 |
> |
rethrow(ex); |
810 |
> |
return tasks; |
811 |
|
} |
812 |
|
|
813 |
|
/** |
814 |
< |
* Returns true if the computation performed by this task has |
815 |
< |
* completed (or has been cancelled). |
816 |
< |
* @return true if this computation has completed |
814 |
> |
* Attempts to cancel execution of this task. This attempt will |
815 |
> |
* fail if the task has already completed or could not be |
816 |
> |
* cancelled for some other reason. If successful, and this task |
817 |
> |
* has not started when {@code cancel} is called, execution of |
818 |
> |
* this task is suppressed. After this method returns |
819 |
> |
* successfully, unless there is an intervening call to {@link |
820 |
> |
* #reinitialize}, subsequent calls to {@link #isCancelled}, |
821 |
> |
* {@link #isDone}, and {@code cancel} will return {@code true} |
822 |
> |
* and calls to {@link #join} and related methods will result in |
823 |
> |
* {@code CancellationException}. |
824 |
> |
* |
825 |
> |
* <p>This method may be overridden in subclasses, but if so, must |
826 |
> |
* still ensure that these properties hold. In particular, the |
827 |
> |
* {@code cancel} method itself must not throw exceptions. |
828 |
> |
* |
829 |
> |
* <p>This method is designed to be invoked by <em>other</em> |
830 |
> |
* tasks. To terminate the current task, you can just return or |
831 |
> |
* throw an unchecked exception from its computation method, or |
832 |
> |
* invoke {@link #completeExceptionally}. |
833 |
> |
* |
834 |
> |
* @param mayInterruptIfRunning this value has no effect in the |
835 |
> |
* default implementation because interrupts are not used to |
836 |
> |
* control cancellation. |
837 |
> |
* |
838 |
> |
* @return {@code true} if this task is now cancelled |
839 |
|
*/ |
840 |
+ |
public boolean cancel(boolean mayInterruptIfRunning) { |
841 |
+ |
return (setCompletion(CANCELLED) & DONE_MASK) == CANCELLED; |
842 |
+ |
} |
843 |
+ |
|
844 |
|
public final boolean isDone() { |
845 |
|
return status < 0; |
846 |
|
} |
847 |
|
|
632 |
– |
/** |
633 |
– |
* Returns true if this task was cancelled. |
634 |
– |
* @return true if this task was cancelled |
635 |
– |
*/ |
848 |
|
public final boolean isCancelled() { |
849 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
849 |
> |
return (status & DONE_MASK) == CANCELLED; |
850 |
|
} |
851 |
|
|
852 |
|
/** |
853 |
< |
* Asserts that the results of this task's computation will not be |
642 |
< |
* used. If a cancellation occurs before atempting to execute this |
643 |
< |
* task, then execution will be suppressed, <code>isCancelled</code> |
644 |
< |
* will report true, and <code>join</code> will result in a |
645 |
< |
* <code>CancellationException</code> being thrown. Otherwise, when |
646 |
< |
* cancellation races with completion, there are no guarantees |
647 |
< |
* about whether <code>isCancelled</code> will report true, whether |
648 |
< |
* <code>join</code> will return normally or via an exception, or |
649 |
< |
* whether these behaviors will remain consistent upon repeated |
650 |
< |
* invocation. |
651 |
< |
* |
652 |
< |
* <p>This method may be overridden in subclasses, but if so, must |
653 |
< |
* still ensure that these minimal properties hold. In particular, |
654 |
< |
* the cancel method itself must not throw exceptions. |
853 |
> |
* Returns {@code true} if this task threw an exception or was cancelled. |
854 |
|
* |
855 |
< |
* <p> This method is designed to be invoked by <em>other</em> |
657 |
< |
* tasks. To terminate the current task, you can just return or |
658 |
< |
* throw an unchecked exception from its computation method, or |
659 |
< |
* invoke <code>completeExceptionally</code>. |
660 |
< |
* |
661 |
< |
* @param mayInterruptIfRunning this value is ignored in the |
662 |
< |
* default implementation because tasks are not in general |
663 |
< |
* cancelled via interruption. |
664 |
< |
* |
665 |
< |
* @return true if this task is now cancelled |
855 |
> |
* @return {@code true} if this task threw an exception or was cancelled |
856 |
|
*/ |
857 |
< |
public boolean cancel(boolean mayInterruptIfRunning) { |
858 |
< |
setCompletion(CANCELLED); |
669 |
< |
return (status & COMPLETION_MASK) == CANCELLED; |
857 |
> |
public final boolean isCompletedAbnormally() { |
858 |
> |
return status < NORMAL; |
859 |
|
} |
860 |
|
|
861 |
|
/** |
862 |
< |
* Returns true if this task threw an exception or was cancelled |
863 |
< |
* @return true if this task threw an exception or was cancelled |
862 |
> |
* Returns {@code true} if this task completed without throwing an |
863 |
> |
* exception and was not cancelled. |
864 |
> |
* |
865 |
> |
* @return {@code true} if this task completed without throwing an |
866 |
> |
* exception and was not cancelled |
867 |
|
*/ |
868 |
< |
public final boolean isCompletedAbnormally() { |
869 |
< |
return (status & COMPLETION_MASK) < NORMAL; |
868 |
> |
public final boolean isCompletedNormally() { |
869 |
> |
return (status & DONE_MASK) == NORMAL; |
870 |
|
} |
871 |
|
|
872 |
|
/** |
873 |
|
* Returns the exception thrown by the base computation, or a |
874 |
< |
* CancellationException if cancelled, or null if none or if the |
875 |
< |
* method has not yet completed. |
876 |
< |
* @return the exception, or null if none |
874 |
> |
* {@code CancellationException} if cancelled, or {@code null} if |
875 |
> |
* none or if the method has not yet completed. |
876 |
> |
* |
877 |
> |
* @return the exception, or {@code null} if none |
878 |
|
*/ |
879 |
|
public final Throwable getException() { |
880 |
< |
int s = status & COMPLETION_MASK; |
881 |
< |
if (s >= NORMAL) |
882 |
< |
return null; |
883 |
< |
if (s == CANCELLED) |
691 |
< |
return new CancellationException(); |
692 |
< |
return exceptionMap.get(this); |
880 |
> |
int s = status & DONE_MASK; |
881 |
> |
return ((s >= NORMAL) ? null : |
882 |
> |
(s == CANCELLED) ? new CancellationException() : |
883 |
> |
getThrowableException()); |
884 |
|
} |
885 |
|
|
886 |
|
/** |
887 |
|
* Completes this task abnormally, and if not already aborted or |
888 |
|
* cancelled, causes it to throw the given exception upon |
889 |
< |
* <code>join</code> and related operations. This method may be used |
889 |
> |
* {@code join} and related operations. This method may be used |
890 |
|
* to induce exceptions in asynchronous tasks, or to force |
891 |
|
* completion of tasks that would not otherwise complete. Its use |
892 |
< |
* in other situations is likely to be wrong. This method is |
893 |
< |
* overridable, but overridden versions must invoke <code>super</code> |
892 |
> |
* in other situations is discouraged. This method is |
893 |
> |
* overridable, but overridden versions must invoke {@code super} |
894 |
|
* implementation to maintain guarantees. |
895 |
|
* |
896 |
< |
* @param ex the exception to throw. If this exception is |
897 |
< |
* not a RuntimeException or Error, the actual exception thrown |
898 |
< |
* will be a RuntimeException with cause ex. |
896 |
> |
* @param ex the exception to throw. If this exception is not a |
897 |
> |
* {@code RuntimeException} or {@code Error}, the actual exception |
898 |
> |
* thrown will be a {@code RuntimeException} with cause {@code ex}. |
899 |
|
*/ |
900 |
|
public void completeExceptionally(Throwable ex) { |
901 |
< |
setDoneExceptionally((ex instanceof RuntimeException) || |
902 |
< |
(ex instanceof Error)? ex : |
903 |
< |
new RuntimeException(ex)); |
901 |
> |
setExceptionalCompletion((ex instanceof RuntimeException) || |
902 |
> |
(ex instanceof Error) ? ex : |
903 |
> |
new RuntimeException(ex)); |
904 |
|
} |
905 |
|
|
906 |
|
/** |
907 |
|
* Completes this task, and if not already aborted or cancelled, |
908 |
< |
* returning a <code>null</code> result upon <code>join</code> and related |
909 |
< |
* operations. This method may be used to provide results for |
910 |
< |
* asynchronous tasks, or to provide alternative handling for |
911 |
< |
* tasks that would not otherwise complete normally. Its use in |
912 |
< |
* other situations is likely to be wrong. This method is |
913 |
< |
* overridable, but overridden versions must invoke <code>super</code> |
914 |
< |
* implementation to maintain guarantees. |
908 |
> |
* returning the given value as the result of subsequent |
909 |
> |
* invocations of {@code join} and related operations. This method |
910 |
> |
* may be used to provide results for asynchronous tasks, or to |
911 |
> |
* provide alternative handling for tasks that would not otherwise |
912 |
> |
* complete normally. Its use in other situations is |
913 |
> |
* discouraged. This method is overridable, but overridden |
914 |
> |
* versions must invoke {@code super} implementation to maintain |
915 |
> |
* guarantees. |
916 |
|
* |
917 |
< |
* @param value the result value for this task. |
917 |
> |
* @param value the result value for this task |
918 |
|
*/ |
919 |
|
public void complete(V value) { |
920 |
|
try { |
921 |
|
setRawResult(value); |
922 |
< |
} catch(Throwable rex) { |
923 |
< |
setDoneExceptionally(rex); |
922 |
> |
} catch (Throwable rex) { |
923 |
> |
setExceptionalCompletion(rex); |
924 |
|
return; |
925 |
|
} |
926 |
< |
setNormalCompletion(); |
926 |
> |
setCompletion(NORMAL); |
927 |
|
} |
928 |
|
|
929 |
< |
public final V get() throws InterruptedException, ExecutionException { |
930 |
< |
ForkJoinWorkerThread w = getWorker(); |
931 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
932 |
< |
awaitDone(w, true); |
933 |
< |
return reportFutureResult(); |
934 |
< |
} |
935 |
< |
|
936 |
< |
public final V get(long timeout, TimeUnit unit) |
937 |
< |
throws InterruptedException, ExecutionException, TimeoutException { |
938 |
< |
ForkJoinWorkerThread w = getWorker(); |
747 |
< |
if (w == null || status < 0 || !w.unpushTask(this) || !tryQuietlyInvoke()) |
748 |
< |
awaitDone(w, unit.toNanos(timeout)); |
749 |
< |
return reportTimedFutureResult(); |
929 |
> |
/** |
930 |
> |
* Completes this task normally without setting a value. The most |
931 |
> |
* recent value established by {@link #setRawResult} (or {@code |
932 |
> |
* null} by default) will be returned as the result of subsequent |
933 |
> |
* invocations of {@code join} and related operations. |
934 |
> |
* |
935 |
> |
* @since 1.8 |
936 |
> |
*/ |
937 |
> |
public final void quietlyComplete() { |
938 |
> |
setCompletion(NORMAL); |
939 |
|
} |
940 |
|
|
941 |
|
/** |
942 |
< |
* Possibly executes other tasks until this task is ready, then |
943 |
< |
* returns the result of the computation. This method may be more |
944 |
< |
* efficient than <code>join</code>, but is only applicable when |
756 |
< |
* there are no potemtial dependencies between continuation of the |
757 |
< |
* current task and that of any other task that might be executed |
758 |
< |
* while helping. (This usually holds for pure divide-and-conquer |
759 |
< |
* tasks). This method may be invoked only from within |
760 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
761 |
< |
* resul!t in exceptions or errors possibly including ClassCastException. |
942 |
> |
* Waits if necessary for the computation to complete, and then |
943 |
> |
* retrieves its result. |
944 |
> |
* |
945 |
|
* @return the computed result |
946 |
+ |
* @throws CancellationException if the computation was cancelled |
947 |
+ |
* @throws ExecutionException if the computation threw an |
948 |
+ |
* exception |
949 |
+ |
* @throws InterruptedException if the current thread is not a |
950 |
+ |
* member of a ForkJoinPool and was interrupted while waiting |
951 |
|
*/ |
952 |
< |
public final V helpJoin() { |
953 |
< |
ForkJoinWorkerThread w = (ForkJoinWorkerThread)(Thread.currentThread()); |
954 |
< |
if (status < 0 || !w.unpushTask(this) || !tryExec()) |
955 |
< |
reportException(busyJoin(w)); |
952 |
> |
public final V get() throws InterruptedException, ExecutionException { |
953 |
> |
int s = (Thread.currentThread() instanceof ForkJoinWorkerThread) ? |
954 |
> |
doJoin() : externalInterruptibleAwaitDone(); |
955 |
> |
Throwable ex; |
956 |
> |
if ((s &= DONE_MASK) == CANCELLED) |
957 |
> |
throw new CancellationException(); |
958 |
> |
if (s == EXCEPTIONAL && (ex = getThrowableException()) != null) |
959 |
> |
throw new ExecutionException(ex); |
960 |
|
return getRawResult(); |
961 |
|
} |
962 |
|
|
963 |
|
/** |
964 |
< |
* Possibly executes other tasks until this task is ready. This |
965 |
< |
* method may be invoked only from within ForkJoinTask |
966 |
< |
* computations. Attempts to invoke in other contexts resul!t in |
967 |
< |
* exceptions or errors possibly including ClassCastException. |
964 |
> |
* Waits if necessary for at most the given time for the computation |
965 |
> |
* to complete, and then retrieves its result, if available. |
966 |
> |
* |
967 |
> |
* @param timeout the maximum time to wait |
968 |
> |
* @param unit the time unit of the timeout argument |
969 |
> |
* @return the computed result |
970 |
> |
* @throws CancellationException if the computation was cancelled |
971 |
> |
* @throws ExecutionException if the computation threw an |
972 |
> |
* exception |
973 |
> |
* @throws InterruptedException if the current thread is not a |
974 |
> |
* member of a ForkJoinPool and was interrupted while waiting |
975 |
> |
* @throws TimeoutException if the wait timed out |
976 |
|
*/ |
977 |
< |
public final void quietlyHelpJoin() { |
978 |
< |
if (status >= 0) { |
979 |
< |
ForkJoinWorkerThread w = |
980 |
< |
(ForkJoinWorkerThread)(Thread.currentThread()); |
981 |
< |
if (!w.unpushTask(this) || !tryQuietlyInvoke()) |
982 |
< |
busyJoin(w); |
977 |
> |
public final V get(long timeout, TimeUnit unit) |
978 |
> |
throws InterruptedException, ExecutionException, TimeoutException { |
979 |
> |
if (Thread.interrupted()) |
980 |
> |
throw new InterruptedException(); |
981 |
> |
// Messy in part because we measure in nanosecs, but wait in millisecs |
982 |
> |
int s; long ms; |
983 |
> |
long ns = unit.toNanos(timeout); |
984 |
> |
if ((s = status) >= 0 && ns > 0L) { |
985 |
> |
long deadline = System.nanoTime() + ns; |
986 |
> |
ForkJoinPool p = null; |
987 |
> |
ForkJoinPool.WorkQueue w = null; |
988 |
> |
Thread t = Thread.currentThread(); |
989 |
> |
if (t instanceof ForkJoinWorkerThread) { |
990 |
> |
ForkJoinWorkerThread wt = (ForkJoinWorkerThread)t; |
991 |
> |
p = wt.pool; |
992 |
> |
w = wt.workQueue; |
993 |
> |
p.helpJoinOnce(w, this); // no retries on failure |
994 |
> |
} |
995 |
> |
else |
996 |
> |
ForkJoinPool.externalHelpJoin(this); |
997 |
> |
boolean canBlock = false; |
998 |
> |
boolean interrupted = false; |
999 |
> |
try { |
1000 |
> |
while ((s = status) >= 0) { |
1001 |
> |
if (w != null && w.qlock < 0) |
1002 |
> |
cancelIgnoringExceptions(this); |
1003 |
> |
else if (!canBlock) { |
1004 |
> |
if (p == null || p.tryCompensate()) |
1005 |
> |
canBlock = true; |
1006 |
> |
} |
1007 |
> |
else { |
1008 |
> |
if ((ms = TimeUnit.NANOSECONDS.toMillis(ns)) > 0L && |
1009 |
> |
U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) { |
1010 |
> |
synchronized (this) { |
1011 |
> |
if (status >= 0) { |
1012 |
> |
try { |
1013 |
> |
wait(ms); |
1014 |
> |
} catch (InterruptedException ie) { |
1015 |
> |
if (p == null) |
1016 |
> |
interrupted = true; |
1017 |
> |
} |
1018 |
> |
} |
1019 |
> |
else |
1020 |
> |
notifyAll(); |
1021 |
> |
} |
1022 |
> |
} |
1023 |
> |
if ((s = status) < 0 || interrupted || |
1024 |
> |
(ns = deadline - System.nanoTime()) <= 0L) |
1025 |
> |
break; |
1026 |
> |
} |
1027 |
> |
} |
1028 |
> |
} finally { |
1029 |
> |
if (p != null && canBlock) |
1030 |
> |
p.incrementActiveCount(); |
1031 |
> |
} |
1032 |
> |
if (interrupted) |
1033 |
> |
throw new InterruptedException(); |
1034 |
> |
} |
1035 |
> |
if ((s &= DONE_MASK) != NORMAL) { |
1036 |
> |
Throwable ex; |
1037 |
> |
if (s == CANCELLED) |
1038 |
> |
throw new CancellationException(); |
1039 |
> |
if (s != EXCEPTIONAL) |
1040 |
> |
throw new TimeoutException(); |
1041 |
> |
if ((ex = getThrowableException()) != null) |
1042 |
> |
throw new ExecutionException(ex); |
1043 |
|
} |
1044 |
+ |
return getRawResult(); |
1045 |
|
} |
1046 |
|
|
1047 |
|
/** |
1048 |
< |
* Joins this task, without returning its result or throwing an |
1048 |
> |
* Joins this task, without returning its result or throwing its |
1049 |
|
* exception. This method may be useful when processing |
1050 |
|
* collections of tasks when some have been cancelled or otherwise |
1051 |
|
* known to have aborted. |
1052 |
|
*/ |
1053 |
|
public final void quietlyJoin() { |
1054 |
< |
if (status >= 0) { |
794 |
< |
ForkJoinWorkerThread w = getWorker(); |
795 |
< |
if (w == null || !w.unpushTask(this) || !tryQuietlyInvoke()) |
796 |
< |
awaitDone(w, true); |
797 |
< |
} |
1054 |
> |
doJoin(); |
1055 |
|
} |
1056 |
|
|
1057 |
|
/** |
1058 |
|
* Commences performing this task and awaits its completion if |
1059 |
< |
* necessary, without returning its result or throwing an |
1060 |
< |
* exception. This method may be useful when processing |
804 |
< |
* collections of tasks when some have been cancelled or otherwise |
805 |
< |
* known to have aborted. |
1059 |
> |
* necessary, without returning its result or throwing its |
1060 |
> |
* exception. |
1061 |
|
*/ |
1062 |
|
public final void quietlyInvoke() { |
1063 |
< |
if (status >= 0 && !tryQuietlyInvoke()) |
809 |
< |
quietlyJoin(); |
1063 |
> |
doInvoke(); |
1064 |
|
} |
1065 |
|
|
1066 |
|
/** |
1067 |
|
* Possibly executes tasks until the pool hosting the current task |
1068 |
< |
* {@link ForkJoinPool#isQuiescent}. This method may be of use in |
1069 |
< |
* designs in which many tasks are forked, but none are explicitly |
1070 |
< |
* joined, instead executing them until all are processed. |
1068 |
> |
* {@link ForkJoinPool#isQuiescent is quiescent}. This method may |
1069 |
> |
* be of use in designs in which many tasks are forked, but none |
1070 |
> |
* are explicitly joined, instead executing them until all are |
1071 |
> |
* processed. |
1072 |
|
*/ |
1073 |
|
public static void helpQuiesce() { |
1074 |
< |
((ForkJoinWorkerThread)(Thread.currentThread())). |
1075 |
< |
helpQuiescePool(); |
1074 |
> |
Thread t; |
1075 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) { |
1076 |
> |
ForkJoinWorkerThread wt = (ForkJoinWorkerThread)t; |
1077 |
> |
wt.pool.helpQuiescePool(wt.workQueue); |
1078 |
> |
} |
1079 |
> |
else |
1080 |
> |
ForkJoinPool.quiesceCommonPool(); |
1081 |
|
} |
1082 |
|
|
1083 |
|
/** |
1084 |
|
* Resets the internal bookkeeping state of this task, allowing a |
1085 |
< |
* subsequent <code>fork</code>. This method allows repeated reuse of |
1085 |
> |
* subsequent {@code fork}. This method allows repeated reuse of |
1086 |
|
* this task, but only if reuse occurs when this task has either |
1087 |
|
* never been forked, or has been forked, then completed and all |
1088 |
|
* outstanding joins of this task have also completed. Effects |
1089 |
< |
* under any other usage conditions are not guaranteed, and are |
1090 |
< |
* almost surely wrong. This method may be useful when executing |
1089 |
> |
* under any other usage conditions are not guaranteed. |
1090 |
> |
* This method may be useful when executing |
1091 |
|
* pre-constructed trees of subtasks in loops. |
1092 |
+ |
* |
1093 |
+ |
* <p>Upon completion of this method, {@code isDone()} reports |
1094 |
+ |
* {@code false}, and {@code getException()} reports {@code |
1095 |
+ |
* null}. However, the value returned by {@code getRawResult} is |
1096 |
+ |
* unaffected. To clear this value, you can invoke {@code |
1097 |
+ |
* setRawResult(null)}. |
1098 |
|
*/ |
1099 |
|
public void reinitialize() { |
1100 |
< |
if ((status & COMPLETION_MASK) == EXCEPTIONAL) |
1101 |
< |
exceptionMap.remove(this); |
1102 |
< |
status = 0; |
1100 |
> |
if ((status & DONE_MASK) == EXCEPTIONAL) |
1101 |
> |
clearExceptionalCompletion(); |
1102 |
> |
else |
1103 |
> |
status = 0; |
1104 |
|
} |
1105 |
|
|
1106 |
|
/** |
1107 |
|
* Returns the pool hosting the current task execution, or null |
1108 |
< |
* if this task is executing outside of any pool. |
1109 |
< |
* @return the pool, or null if none. |
1108 |
> |
* if this task is executing outside of any ForkJoinPool. |
1109 |
> |
* |
1110 |
> |
* @see #inForkJoinPool |
1111 |
> |
* @return the pool, or {@code null} if none |
1112 |
|
*/ |
1113 |
|
public static ForkJoinPool getPool() { |
1114 |
|
Thread t = Thread.currentThread(); |
1115 |
< |
return ((t instanceof ForkJoinWorkerThread)? |
1116 |
< |
((ForkJoinWorkerThread)t).pool : null); |
1115 |
> |
return (t instanceof ForkJoinWorkerThread) ? |
1116 |
> |
((ForkJoinWorkerThread) t).pool : null; |
1117 |
> |
} |
1118 |
> |
|
1119 |
> |
/** |
1120 |
> |
* Returns {@code true} if the current thread is a {@link |
1121 |
> |
* ForkJoinWorkerThread} executing as a ForkJoinPool computation. |
1122 |
> |
* |
1123 |
> |
* @return {@code true} if the current thread is a {@link |
1124 |
> |
* ForkJoinWorkerThread} executing as a ForkJoinPool computation, |
1125 |
> |
* or {@code false} otherwise |
1126 |
> |
*/ |
1127 |
> |
public static boolean inForkJoinPool() { |
1128 |
> |
return Thread.currentThread() instanceof ForkJoinWorkerThread; |
1129 |
|
} |
1130 |
|
|
1131 |
|
/** |
1132 |
|
* Tries to unschedule this task for execution. This method will |
1133 |
< |
* typically succeed if this task is the most recently forked task |
1134 |
< |
* by the current thread, and has not commenced executing in |
1135 |
< |
* another thread. This method may be useful when arranging |
1136 |
< |
* alternative local processing of tasks that could have been, but |
1137 |
< |
* were not, stolen. This method may be invoked only from within |
1138 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
1139 |
< |
* result in exceptions or errors possibly including ClassCastException. |
859 |
< |
* @return true if unforked |
1133 |
> |
* typically (but is not guaranteed to) succeed if this task is |
1134 |
> |
* the most recently forked task by the current thread, and has |
1135 |
> |
* not commenced executing in another thread. This method may be |
1136 |
> |
* useful when arranging alternative local processing of tasks |
1137 |
> |
* that could have been, but were not, stolen. |
1138 |
> |
* |
1139 |
> |
* @return {@code true} if unforked |
1140 |
|
*/ |
1141 |
|
public boolean tryUnfork() { |
1142 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).unpushTask(this); |
1142 |
> |
Thread t; |
1143 |
> |
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1144 |
> |
((ForkJoinWorkerThread)t).workQueue.tryUnpush(this) : |
1145 |
> |
ForkJoinPool.tryExternalUnpush(this)); |
1146 |
|
} |
1147 |
|
|
1148 |
|
/** |
1150 |
|
* forked by the current worker thread but not yet executed. This |
1151 |
|
* value may be useful for heuristic decisions about whether to |
1152 |
|
* fork other tasks. |
1153 |
+ |
* |
1154 |
|
* @return the number of tasks |
1155 |
|
*/ |
1156 |
|
public static int getQueuedTaskCount() { |
1157 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
1158 |
< |
getQueueSize(); |
1157 |
> |
Thread t; ForkJoinPool.WorkQueue q; |
1158 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
1159 |
> |
q = ((ForkJoinWorkerThread)t).workQueue; |
1160 |
> |
else |
1161 |
> |
q = ForkJoinPool.commonSubmitterQueue(); |
1162 |
> |
return (q == null) ? 0 : q.queueSize(); |
1163 |
|
} |
1164 |
|
|
1165 |
|
/** |
1166 |
< |
* Returns a estimate of how many more locally queued tasks are |
1166 |
> |
* Returns an estimate of how many more locally queued tasks are |
1167 |
|
* held by the current worker thread than there are other worker |
1168 |
< |
* threads that might steal them. This value may be useful for |
1168 |
> |
* threads that might steal them, or zero if this thread is not |
1169 |
> |
* operating in a ForkJoinPool. This value may be useful for |
1170 |
|
* heuristic decisions about whether to fork other tasks. In many |
1171 |
|
* usages of ForkJoinTasks, at steady state, each worker should |
1172 |
|
* aim to maintain a small constant surplus (for example, 3) of |
1173 |
|
* tasks, and to process computations locally if this threshold is |
1174 |
|
* exceeded. |
1175 |
+ |
* |
1176 |
|
* @return the surplus number of tasks, which may be negative |
1177 |
|
*/ |
1178 |
|
public static int getSurplusQueuedTaskCount() { |
1179 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())) |
890 |
< |
.getEstimatedSurplusTaskCount(); |
1179 |
> |
return ForkJoinPool.getSurplusQueuedTaskCount(); |
1180 |
|
} |
1181 |
|
|
1182 |
|
// Extension methods |
1183 |
|
|
1184 |
|
/** |
1185 |
< |
* Returns the result that would be returned by <code>join</code>, |
1186 |
< |
* even if this task completed abnormally, or null if this task is |
1187 |
< |
* not known to have been completed. This method is designed to |
1188 |
< |
* aid debugging, as well as to support extensions. Its use in any |
1189 |
< |
* other context is discouraged. |
1185 |
> |
* Returns the result that would be returned by {@link #join}, even |
1186 |
> |
* if this task completed abnormally, or {@code null} if this task |
1187 |
> |
* is not known to have been completed. This method is designed |
1188 |
> |
* to aid debugging, as well as to support extensions. Its use in |
1189 |
> |
* any other context is discouraged. |
1190 |
|
* |
1191 |
< |
* @return the result, or null if not completed. |
1191 |
> |
* @return the result, or {@code null} if not completed |
1192 |
|
*/ |
1193 |
|
public abstract V getRawResult(); |
1194 |
|
|
1202 |
|
protected abstract void setRawResult(V value); |
1203 |
|
|
1204 |
|
/** |
1205 |
< |
* Immediately performs the base action of this task. This method |
1206 |
< |
* is designed to support extensions, and should not in general be |
1207 |
< |
* called otherwise. The return value controls whether this task |
1208 |
< |
* is considered to be done normally. It may return false in |
1205 |
> |
* Immediately performs the base action of this task and returns |
1206 |
> |
* true if, upon return from this method, this task is guaranteed |
1207 |
> |
* to have completed normally. This method may return false |
1208 |
> |
* otherwise, to indicate that this task is not necessarily |
1209 |
> |
* complete (or is not known to be complete), for example in |
1210 |
|
* asynchronous actions that require explicit invocations of |
1211 |
< |
* <code>complete</code> to become joinable. It may throw exceptions |
1212 |
< |
* to indicate abnormal exit. |
1213 |
< |
* @return true if completed normally |
1214 |
< |
* @throws Error or RuntimeException if encountered during computation |
1211 |
> |
* completion methods. This method may also throw an (unchecked) |
1212 |
> |
* exception to indicate abnormal exit. This method is designed to |
1213 |
> |
* support extensions, and should not in general be called |
1214 |
> |
* otherwise. |
1215 |
> |
* |
1216 |
> |
* @return {@code true} if this task is known to have completed normally |
1217 |
|
*/ |
1218 |
|
protected abstract boolean exec(); |
1219 |
|
|
1220 |
|
/** |
1221 |
< |
* Returns, but does not unschedule or execute, the task most |
1222 |
< |
* recently forked by the current thread but not yet executed, if |
1223 |
< |
* one is available. There is no guarantee that this task will |
1224 |
< |
* actually be polled or executed next. |
1225 |
< |
* This method is designed primarily to support extensions, |
1226 |
< |
* and is unlikely to be useful otherwise. |
1227 |
< |
* This method may be invoked only from within |
1228 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
937 |
< |
* result in exceptions or errors possibly including ClassCastException. |
1221 |
> |
* Returns, but does not unschedule or execute, a task queued by |
1222 |
> |
* the current thread but not yet executed, if one is immediately |
1223 |
> |
* available. There is no guarantee that this task will actually |
1224 |
> |
* be polled or executed next. Conversely, this method may return |
1225 |
> |
* null even if a task exists but cannot be accessed without |
1226 |
> |
* contention with other threads. This method is designed |
1227 |
> |
* primarily to support extensions, and is unlikely to be useful |
1228 |
> |
* otherwise. |
1229 |
|
* |
1230 |
< |
* @return the next task, or null if none are available |
1230 |
> |
* @return the next task, or {@code null} if none are available |
1231 |
|
*/ |
1232 |
|
protected static ForkJoinTask<?> peekNextLocalTask() { |
1233 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).peekTask(); |
1233 |
> |
Thread t; ForkJoinPool.WorkQueue q; |
1234 |
> |
if ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) |
1235 |
> |
q = ((ForkJoinWorkerThread)t).workQueue; |
1236 |
> |
else |
1237 |
> |
q = ForkJoinPool.commonSubmitterQueue(); |
1238 |
> |
return (q == null) ? null : q.peek(); |
1239 |
|
} |
1240 |
|
|
1241 |
|
/** |
1242 |
< |
* Unschedules and returns, without executing, the task most |
1243 |
< |
* recently forked by the current thread but not yet executed. |
1244 |
< |
* This method is designed primarily to support extensions, |
1245 |
< |
* and is unlikely to be useful otherwise. |
1246 |
< |
* This method may be invoked only from within |
951 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
952 |
< |
* result in exceptions or errors possibly including ClassCastException. |
1242 |
> |
* Unschedules and returns, without executing, the next task |
1243 |
> |
* queued by the current thread but not yet executed, if the |
1244 |
> |
* current thread is operating in a ForkJoinPool. This method is |
1245 |
> |
* designed primarily to support extensions, and is unlikely to be |
1246 |
> |
* useful otherwise. |
1247 |
|
* |
1248 |
< |
* @return the next task, or null if none are available |
1248 |
> |
* @return the next task, or {@code null} if none are available |
1249 |
|
*/ |
1250 |
|
protected static ForkJoinTask<?> pollNextLocalTask() { |
1251 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())).popTask(); |
1251 |
> |
Thread t; |
1252 |
> |
return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1253 |
> |
((ForkJoinWorkerThread)t).workQueue.nextLocalTask() : |
1254 |
> |
null; |
1255 |
|
} |
1256 |
|
|
1257 |
|
/** |
1258 |
< |
* Unschedules and returns, without executing, the task most |
1259 |
< |
* recently forked by the current thread but not yet executed, if |
1260 |
< |
* one is available, or if not available, a task that was forked |
1261 |
< |
* by some other thread, if available. Availability may be |
1262 |
< |
* transient, so a <code>null</code> result does not necessarily |
1263 |
< |
* imply quiecence of the pool this task is operating in. |
1264 |
< |
* This method is designed primarily to support extensions, |
1265 |
< |
* and is unlikely to be useful otherwise. |
1266 |
< |
* This method may be invoked only from within |
970 |
< |
* ForkJoinTask computations. Attempts to invoke in other contexts |
971 |
< |
* result in exceptions or errors possibly including ClassCastException. |
1258 |
> |
* If the current thread is operating in a ForkJoinPool, |
1259 |
> |
* unschedules and returns, without executing, the next task |
1260 |
> |
* queued by the current thread but not yet executed, if one is |
1261 |
> |
* available, or if not available, a task that was forked by some |
1262 |
> |
* other thread, if available. Availability may be transient, so a |
1263 |
> |
* {@code null} result does not necessarily imply quiescence of |
1264 |
> |
* the pool this task is operating in. This method is designed |
1265 |
> |
* primarily to support extensions, and is unlikely to be useful |
1266 |
> |
* otherwise. |
1267 |
|
* |
1268 |
< |
* @return a task, or null if none are available |
1268 |
> |
* @return a task, or {@code null} if none are available |
1269 |
|
*/ |
1270 |
|
protected static ForkJoinTask<?> pollTask() { |
1271 |
< |
return ((ForkJoinWorkerThread)(Thread.currentThread())). |
1272 |
< |
pollTask(); |
1271 |
> |
Thread t; ForkJoinWorkerThread wt; |
1272 |
> |
return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ? |
1273 |
> |
(wt = (ForkJoinWorkerThread)t).pool.nextTaskFor(wt.workQueue) : |
1274 |
> |
null; |
1275 |
> |
} |
1276 |
> |
|
1277 |
> |
// tag operations |
1278 |
> |
|
1279 |
> |
/** |
1280 |
> |
* Returns the tag for this task. |
1281 |
> |
* |
1282 |
> |
* @return the tag for this task |
1283 |
> |
* @since 1.8 |
1284 |
> |
*/ |
1285 |
> |
public final short getForkJoinTaskTag() { |
1286 |
> |
return (short)status; |
1287 |
> |
} |
1288 |
> |
|
1289 |
> |
/** |
1290 |
> |
* Atomically sets the tag value for this task. |
1291 |
> |
* |
1292 |
> |
* @param tag the tag value |
1293 |
> |
* @return the previous value of the tag |
1294 |
> |
* @since 1.8 |
1295 |
> |
*/ |
1296 |
> |
public final short setForkJoinTaskTag(short tag) { |
1297 |
> |
for (int s;;) { |
1298 |
> |
if (U.compareAndSwapInt(this, STATUS, s = status, |
1299 |
> |
(s & ~SMASK) | (tag & SMASK))) |
1300 |
> |
return (short)s; |
1301 |
> |
} |
1302 |
> |
} |
1303 |
> |
|
1304 |
> |
/** |
1305 |
> |
* Atomically conditionally sets the tag value for this task. |
1306 |
> |
* Among other applications, tags can be used as visit markers |
1307 |
> |
* in tasks operating on graphs, as in methods that check: {@code |
1308 |
> |
* if (task.compareAndSetForkJoinTaskTag((short)0, (short)1))} |
1309 |
> |
* before processing, otherwise exiting because the node has |
1310 |
> |
* already been visited. |
1311 |
> |
* |
1312 |
> |
* @param e the expected tag value |
1313 |
> |
* @param tag the new tag value |
1314 |
> |
* @return true if successful; i.e., the current value was |
1315 |
> |
* equal to e and is now tag. |
1316 |
> |
* @since 1.8 |
1317 |
> |
*/ |
1318 |
> |
public final boolean compareAndSetForkJoinTaskTag(short e, short tag) { |
1319 |
> |
for (int s;;) { |
1320 |
> |
if ((short)(s = status) != e) |
1321 |
> |
return false; |
1322 |
> |
if (U.compareAndSwapInt(this, STATUS, s, |
1323 |
> |
(s & ~SMASK) | (tag & SMASK))) |
1324 |
> |
return true; |
1325 |
> |
} |
1326 |
> |
} |
1327 |
> |
|
1328 |
> |
/** |
1329 |
> |
* Adaptor for Runnables. This implements RunnableFuture |
1330 |
> |
* to be compliant with AbstractExecutorService constraints |
1331 |
> |
* when used in ForkJoinPool. |
1332 |
> |
*/ |
1333 |
> |
static final class AdaptedRunnable<T> extends ForkJoinTask<T> |
1334 |
> |
implements RunnableFuture<T> { |
1335 |
> |
final Runnable runnable; |
1336 |
> |
T result; |
1337 |
> |
AdaptedRunnable(Runnable runnable, T result) { |
1338 |
> |
if (runnable == null) throw new NullPointerException(); |
1339 |
> |
this.runnable = runnable; |
1340 |
> |
this.result = result; // OK to set this even before completion |
1341 |
> |
} |
1342 |
> |
public final T getRawResult() { return result; } |
1343 |
> |
public final void setRawResult(T v) { result = v; } |
1344 |
> |
public final boolean exec() { runnable.run(); return true; } |
1345 |
> |
public final void run() { invoke(); } |
1346 |
> |
private static final long serialVersionUID = 5232453952276885070L; |
1347 |
> |
} |
1348 |
> |
|
1349 |
> |
/** |
1350 |
> |
* Adaptor for Runnables without results |
1351 |
> |
*/ |
1352 |
> |
static final class AdaptedRunnableAction extends ForkJoinTask<Void> |
1353 |
> |
implements RunnableFuture<Void> { |
1354 |
> |
final Runnable runnable; |
1355 |
> |
AdaptedRunnableAction(Runnable runnable) { |
1356 |
> |
if (runnable == null) throw new NullPointerException(); |
1357 |
> |
this.runnable = runnable; |
1358 |
> |
} |
1359 |
> |
public final Void getRawResult() { return null; } |
1360 |
> |
public final void setRawResult(Void v) { } |
1361 |
> |
public final boolean exec() { runnable.run(); return true; } |
1362 |
> |
public final void run() { invoke(); } |
1363 |
> |
private static final long serialVersionUID = 5232453952276885070L; |
1364 |
> |
} |
1365 |
> |
|
1366 |
> |
/** |
1367 |
> |
* Adaptor for Callables |
1368 |
> |
*/ |
1369 |
> |
static final class AdaptedCallable<T> extends ForkJoinTask<T> |
1370 |
> |
implements RunnableFuture<T> { |
1371 |
> |
final Callable<? extends T> callable; |
1372 |
> |
T result; |
1373 |
> |
AdaptedCallable(Callable<? extends T> callable) { |
1374 |
> |
if (callable == null) throw new NullPointerException(); |
1375 |
> |
this.callable = callable; |
1376 |
> |
} |
1377 |
> |
public final T getRawResult() { return result; } |
1378 |
> |
public final void setRawResult(T v) { result = v; } |
1379 |
> |
public final boolean exec() { |
1380 |
> |
try { |
1381 |
> |
result = callable.call(); |
1382 |
> |
return true; |
1383 |
> |
} catch (Error err) { |
1384 |
> |
throw err; |
1385 |
> |
} catch (RuntimeException rex) { |
1386 |
> |
throw rex; |
1387 |
> |
} catch (Exception ex) { |
1388 |
> |
throw new RuntimeException(ex); |
1389 |
> |
} |
1390 |
> |
} |
1391 |
> |
public final void run() { invoke(); } |
1392 |
> |
private static final long serialVersionUID = 2838392045355241008L; |
1393 |
> |
} |
1394 |
> |
|
1395 |
> |
/** |
1396 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1397 |
> |
* method of the given {@code Runnable} as its action, and returns |
1398 |
> |
* a null result upon {@link #join}. |
1399 |
> |
* |
1400 |
> |
* @param runnable the runnable action |
1401 |
> |
* @return the task |
1402 |
> |
*/ |
1403 |
> |
public static ForkJoinTask<?> adapt(Runnable runnable) { |
1404 |
> |
return new AdaptedRunnableAction(runnable); |
1405 |
> |
} |
1406 |
> |
|
1407 |
> |
/** |
1408 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code run} |
1409 |
> |
* method of the given {@code Runnable} as its action, and returns |
1410 |
> |
* the given result upon {@link #join}. |
1411 |
> |
* |
1412 |
> |
* @param runnable the runnable action |
1413 |
> |
* @param result the result upon completion |
1414 |
> |
* @return the task |
1415 |
> |
*/ |
1416 |
> |
public static <T> ForkJoinTask<T> adapt(Runnable runnable, T result) { |
1417 |
> |
return new AdaptedRunnable<T>(runnable, result); |
1418 |
> |
} |
1419 |
> |
|
1420 |
> |
/** |
1421 |
> |
* Returns a new {@code ForkJoinTask} that performs the {@code call} |
1422 |
> |
* method of the given {@code Callable} as its action, and returns |
1423 |
> |
* its result upon {@link #join}, translating any checked exceptions |
1424 |
> |
* encountered into {@code RuntimeException}. |
1425 |
> |
* |
1426 |
> |
* @param callable the callable action |
1427 |
> |
* @return the task |
1428 |
> |
*/ |
1429 |
> |
public static <T> ForkJoinTask<T> adapt(Callable<? extends T> callable) { |
1430 |
> |
return new AdaptedCallable<T>(callable); |
1431 |
|
} |
1432 |
|
|
1433 |
|
// Serialization support |
1435 |
|
private static final long serialVersionUID = -7721805057305804111L; |
1436 |
|
|
1437 |
|
/** |
1438 |
< |
* Save the state to a stream. |
1438 |
> |
* Saves this task to a stream (that is, serializes it). |
1439 |
|
* |
1440 |
|
* @serialData the current run status and the exception thrown |
1441 |
< |
* during execution, or null if none. |
989 |
< |
* @param s the stream |
1441 |
> |
* during execution, or {@code null} if none |
1442 |
|
*/ |
1443 |
|
private void writeObject(java.io.ObjectOutputStream s) |
1444 |
|
throws java.io.IOException { |
1447 |
|
} |
1448 |
|
|
1449 |
|
/** |
1450 |
< |
* Reconstitute the instance from a stream. |
999 |
< |
* @param s the stream |
1450 |
> |
* Reconstitutes this task from a stream (that is, deserializes it). |
1451 |
|
*/ |
1452 |
|
private void readObject(java.io.ObjectInputStream s) |
1453 |
|
throws java.io.IOException, ClassNotFoundException { |
1454 |
|
s.defaultReadObject(); |
1004 |
– |
status &= ~INTERNAL_SIGNAL_MASK; // clear internal signal counts |
1005 |
– |
status |= EXTERNAL_SIGNAL; // conservatively set external signal |
1455 |
|
Object ex = s.readObject(); |
1456 |
|
if (ex != null) |
1457 |
< |
setDoneExceptionally((Throwable)ex); |
1457 |
> |
setExceptionalCompletion((Throwable)ex); |
1458 |
|
} |
1459 |
|
|
1460 |
< |
// Temporary Unsafe mechanics for preliminary release |
1461 |
< |
|
1462 |
< |
static final Unsafe _unsafe; |
1014 |
< |
static final long statusOffset; |
1460 |
> |
// Unsafe mechanics |
1461 |
> |
private static final sun.misc.Unsafe U; |
1462 |
> |
private static final long STATUS; |
1463 |
|
|
1464 |
|
static { |
1465 |
+ |
exceptionTableLock = new ReentrantLock(); |
1466 |
+ |
exceptionTableRefQueue = new ReferenceQueue<Object>(); |
1467 |
+ |
exceptionTable = new ExceptionNode[EXCEPTION_MAP_CAPACITY]; |
1468 |
|
try { |
1469 |
< |
if (ForkJoinTask.class.getClassLoader() != null) { |
1470 |
< |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
1471 |
< |
f.setAccessible(true); |
1472 |
< |
_unsafe = (Unsafe)f.get(null); |
1473 |
< |
} |
1474 |
< |
else |
1475 |
< |
_unsafe = Unsafe.getUnsafe(); |
1025 |
< |
statusOffset = _unsafe.objectFieldOffset |
1026 |
< |
(ForkJoinTask.class.getDeclaredField("status")); |
1027 |
< |
} catch (Exception ex) { throw new Error(ex); } |
1469 |
> |
U = getUnsafe(); |
1470 |
> |
Class<?> k = ForkJoinTask.class; |
1471 |
> |
STATUS = U.objectFieldOffset |
1472 |
> |
(k.getDeclaredField("status")); |
1473 |
> |
} catch (Exception e) { |
1474 |
> |
throw new Error(e); |
1475 |
> |
} |
1476 |
|
} |
1477 |
|
|
1478 |
+ |
/** |
1479 |
+ |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1480 |
+ |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1481 |
+ |
* into a jdk. |
1482 |
+ |
* |
1483 |
+ |
* @return a sun.misc.Unsafe |
1484 |
+ |
*/ |
1485 |
+ |
private static sun.misc.Unsafe getUnsafe() { |
1486 |
+ |
try { |
1487 |
+ |
return sun.misc.Unsafe.getUnsafe(); |
1488 |
+ |
} catch (SecurityException tryReflectionInstead) {} |
1489 |
+ |
try { |
1490 |
+ |
return java.security.AccessController.doPrivileged |
1491 |
+ |
(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1492 |
+ |
public sun.misc.Unsafe run() throws Exception { |
1493 |
+ |
Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class; |
1494 |
+ |
for (java.lang.reflect.Field f : k.getDeclaredFields()) { |
1495 |
+ |
f.setAccessible(true); |
1496 |
+ |
Object x = f.get(null); |
1497 |
+ |
if (k.isInstance(x)) |
1498 |
+ |
return k.cast(x); |
1499 |
+ |
} |
1500 |
+ |
throw new NoSuchFieldError("the Unsafe"); |
1501 |
+ |
}}); |
1502 |
+ |
} catch (java.security.PrivilegedActionException e) { |
1503 |
+ |
throw new RuntimeException("Could not initialize intrinsics", |
1504 |
+ |
e.getCause()); |
1505 |
+ |
} |
1506 |
+ |
} |
1507 |
|
} |