| 12 |
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import java.util.concurrent.RejectedExecutionException; |
| 13 |
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|
| 14 |
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/** |
| 15 |
< |
* A thread managed by a {@link ForkJoinPool}. This class is |
| 16 |
< |
* subclassable solely for the sake of adding functionality -- there |
| 17 |
< |
* are no overridable methods dealing with scheduling or execution. |
| 18 |
< |
* However, you can override initialization and termination methods |
| 19 |
< |
* surrounding the main task processing loop. If you do create such a |
| 20 |
< |
* subclass, you will also need to supply a custom {@link |
| 21 |
< |
* ForkJoinPool.ForkJoinWorkerThreadFactory} to use it in a {@code |
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< |
* ForkJoinPool}. |
| 15 |
> |
* A thread managed by a {@link ForkJoinPool}, which executes |
| 16 |
> |
* {@link ForkJoinTask}s. |
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> |
* This class is subclassable solely for the sake of adding |
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> |
* functionality -- there are no overridable methods dealing with |
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> |
* scheduling or execution. However, you can override initialization |
| 20 |
> |
* and termination methods surrounding the main task processing loop. |
| 21 |
> |
* If you do create such a subclass, you will also need to supply a |
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> |
* custom {@link ForkJoinPool.ForkJoinWorkerThreadFactory} to use it |
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> |
* in a {@code ForkJoinPool}. |
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* |
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* @since 1.7 |
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* @author Doug Lea |
| 349 |
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/** |
| 350 |
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* Initializes internal state after construction but before |
| 351 |
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* processing any tasks. If you override this method, you must |
| 352 |
< |
* invoke @code{super.onStart()} at the beginning of the method. |
| 352 |
> |
* invoke {@code super.onStart()} at the beginning of the method. |
| 353 |
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* Initialization requires care: Most fields must have legal |
| 354 |
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* default values, to ensure that attempted accesses from other |
| 355 |
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* threads work correctly even before this thread starts |
| 357 |
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*/ |
| 358 |
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protected void onStart() { |
| 359 |
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int rs = seedGenerator.nextInt(); |
| 360 |
< |
seed = rs == 0? 1 : rs; // seed must be nonzero |
| 360 |
> |
seed = (rs == 0) ? 1 : rs; // seed must be nonzero |
| 361 |
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|
| 362 |
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// Allocate name string and arrays in this thread |
| 363 |
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String pid = Integer.toString(pool.getPoolNumber()); |
| 399 |
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/** |
| 400 |
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* This method is required to be public, but should never be |
| 401 |
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* called explicitly. It performs the main run loop to execute |
| 402 |
< |
* ForkJoinTasks. |
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> |
* {@link ForkJoinTask}s. |
| 403 |
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*/ |
| 404 |
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public void run() { |
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Throwable exception = null; |
| 601 |
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if (t == null) // lost to stealer |
| 602 |
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break; |
| 603 |
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if (UNSAFE.compareAndSwapObject(q, u, t, null)) { |
| 604 |
+ |
/* |
| 605 |
+ |
* Note: here and in related methods, as a |
| 606 |
+ |
* performance (not correctness) issue, we'd like |
| 607 |
+ |
* to encourage compiler not to arbitrarily |
| 608 |
+ |
* postpone setting sp after successful CAS. |
| 609 |
+ |
* Currently there is no intrinsic for arranging |
| 610 |
+ |
* this, but using Unsafe putOrderedInt may be a |
| 611 |
+ |
* preferable strategy on some compilers even |
| 612 |
+ |
* though its main effect is a pre-, not post- |
| 613 |
+ |
* fence. To simplify possible changes, the option |
| 614 |
+ |
* is left in comments next to the associated |
| 615 |
+ |
* assignments. |
| 616 |
+ |
*/ |
| 617 |
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sp = s; // putOrderedInt may encourage more timely write |
| 618 |
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// UNSAFE.putOrderedInt(this, spOffset, s); |
| 619 |
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return t; |
| 870 |
|
*/ |
| 871 |
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final void cancelTasks() { |
| 872 |
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ForkJoinTask<?> cj = currentJoin; // try to cancel ongoing tasks |
| 873 |
< |
if (cj != null) { |
| 860 |
< |
currentJoin = null; |
| 873 |
> |
if (cj != null && cj.status >= 0) { |
| 874 |
|
cj.cancelIgnoringExceptions(); |
| 875 |
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try { |
| 876 |
|
this.interrupt(); // awaken wait |
| 878 |
|
} |
| 879 |
|
} |
| 880 |
|
ForkJoinTask<?> cs = currentSteal; |
| 881 |
< |
if (cs != null) { |
| 869 |
< |
currentSteal = null; |
| 881 |
> |
if (cs != null && cs.status >= 0) |
| 882 |
|
cs.cancelIgnoringExceptions(); |
| 871 |
– |
} |
| 883 |
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while (base != sp) { |
| 884 |
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ForkJoinTask<?> t = deqTask(); |
| 885 |
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if (t != null) |
| 949 |
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// currentJoin only written by this thread; only need ordered store |
| 950 |
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ForkJoinTask<?> prevJoin = currentJoin; |
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UNSAFE.putOrderedObject(this, currentJoinOffset, joinMe); |
| 952 |
< |
if (isTerminating()) // cancel if shutting down |
| 942 |
< |
joinMe.cancelIgnoringExceptions(); |
| 943 |
< |
else |
| 944 |
< |
pool.awaitJoin(joinMe, this, timed, nanos); |
| 952 |
> |
pool.awaitJoin(joinMe, this, timed, nanos); |
| 953 |
|
UNSAFE.putOrderedObject(this, currentJoinOffset, prevJoin); |
| 954 |
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} |
| 955 |
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|
| 956 |
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/** |
| 949 |
– |
* Run tasks in local queue until given task is done. |
| 950 |
– |
* Not currently used because it complicates semantics. |
| 951 |
– |
* |
| 952 |
– |
* @param joinMe the task to join |
| 953 |
– |
*/ |
| 954 |
– |
private void localHelpJoinTask(ForkJoinTask<?> joinMe) { |
| 955 |
– |
int s; |
| 956 |
– |
ForkJoinTask<?>[] q; |
| 957 |
– |
while (joinMe.status >= 0 && (s = sp) != base && (q = queue) != null) { |
| 958 |
– |
int i = (q.length - 1) & --s; |
| 959 |
– |
long u = (i << qShift) + qBase; // raw offset |
| 960 |
– |
ForkJoinTask<?> t = q[i]; |
| 961 |
– |
if (t == null) // lost to a stealer |
| 962 |
– |
break; |
| 963 |
– |
if (UNSAFE.compareAndSwapObject(q, u, t, null)) { |
| 964 |
– |
/* |
| 965 |
– |
* This recheck (and similarly in helpJoinTask) |
| 966 |
– |
* handles cases where joinMe is independently |
| 967 |
– |
* cancelled or forced even though there is other work |
| 968 |
– |
* available. Back out of the pop by putting t back |
| 969 |
– |
* into slot before we commit by writing sp. |
| 970 |
– |
*/ |
| 971 |
– |
if (joinMe.status < 0) { |
| 972 |
– |
UNSAFE.putObjectVolatile(q, u, t); |
| 973 |
– |
break; |
| 974 |
– |
} |
| 975 |
– |
sp = s; |
| 976 |
– |
// UNSAFE.putOrderedInt(this, spOffset, s); |
| 977 |
– |
t.quietlyExec(); |
| 978 |
– |
} |
| 979 |
– |
} |
| 980 |
– |
} |
| 981 |
– |
|
| 982 |
– |
/** |
| 957 |
|
* Tries to locate and help perform tasks for a stealer of the |
| 958 |
|
* given task, or in turn one of its stealers. Traces |
| 959 |
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* currentSteal->currentJoin links looking for a thread working on |
| 968 |
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* don't work out. |
| 969 |
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* |
| 970 |
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* @param joinMe the task to join |
| 971 |
< |
*/ |
| 972 |
< |
final void helpJoinTask(ForkJoinTask<?> joinMe) { |
| 973 |
< |
ForkJoinWorkerThread[] ws; |
| 974 |
< |
int n; |
| 975 |
< |
if (joinMe.status < 0) // already done |
| 976 |
< |
return; |
| 977 |
< |
if ((ws = pool.workers) == null || (n = ws.length) <= 1) |
| 978 |
< |
return; // need at least 2 workers |
| 979 |
< |
|
| 980 |
< |
ForkJoinTask<?> task = joinMe; // base of chain |
| 981 |
< |
ForkJoinWorkerThread thread = this; // thread with stolen task |
| 982 |
< |
for (int d = 0; d < MAX_HELP_DEPTH; ++d) { // chain length |
| 983 |
< |
// Try to find v, the stealer of task, by first using hint |
| 984 |
< |
ForkJoinWorkerThread v = ws[thread.stealHint & (n - 1)]; |
| 985 |
< |
if (v == null || v.currentSteal != task) { |
| 986 |
< |
for (int j = 0; ; ++j) { // search array |
| 987 |
< |
if (j < n) { |
| 988 |
< |
ForkJoinTask<?> vs; |
| 989 |
< |
if ((v = ws[j]) != null && v != this && |
| 990 |
< |
(vs = v.currentSteal) != null) { |
| 991 |
< |
if (joinMe.status < 0 || task.status < 0) |
| 992 |
< |
return; // stale or done |
| 993 |
< |
if (vs == task) { |
| 994 |
< |
thread.stealHint = j; |
| 995 |
< |
break; // save hint for next time |
| 971 |
> |
* @param running if false, then must update pool count upon |
| 972 |
> |
* running a task |
| 973 |
> |
* @return value of running on exit |
| 974 |
> |
*/ |
| 975 |
> |
final boolean helpJoinTask(ForkJoinTask<?> joinMe, boolean running) { |
| 976 |
> |
/* |
| 977 |
> |
* Initial checks to (1) abort if terminating; (2) clean out |
| 978 |
> |
* old cancelled tasks from local queue; (3) if joinMe is next |
| 979 |
> |
* task, run it; (4) omit scan if local queue nonempty (since |
| 980 |
> |
* it may contain non-descendents of joinMe). |
| 981 |
> |
*/ |
| 982 |
> |
ForkJoinPool p = pool; |
| 983 |
> |
for (;;) { |
| 984 |
> |
ForkJoinTask<?>[] q; |
| 985 |
> |
int s; |
| 986 |
> |
if (joinMe.status < 0) |
| 987 |
> |
return running; |
| 988 |
> |
else if ((runState & TERMINATING) != 0) { |
| 989 |
> |
joinMe.cancelIgnoringExceptions(); |
| 990 |
> |
return running; |
| 991 |
> |
} |
| 992 |
> |
else if ((s = sp) == base || (q = queue) == null) |
| 993 |
> |
break; // queue empty |
| 994 |
> |
else { |
| 995 |
> |
int i = (q.length - 1) & --s; |
| 996 |
> |
long u = (i << qShift) + qBase; // raw offset |
| 997 |
> |
ForkJoinTask<?> t = q[i]; |
| 998 |
> |
if (t == null) |
| 999 |
> |
break; // lost to a stealer |
| 1000 |
> |
else if (t != joinMe && t.status >= 0) |
| 1001 |
> |
return running; // cannot safely help |
| 1002 |
> |
else if ((running || |
| 1003 |
> |
(running = p.tryIncrementRunningCount())) && |
| 1004 |
> |
UNSAFE.compareAndSwapObject(q, u, t, null)) { |
| 1005 |
> |
sp = s; // putOrderedInt may encourage more timely write |
| 1006 |
> |
// UNSAFE.putOrderedInt(this, spOffset, s); |
| 1007 |
> |
t.quietlyExec(); |
| 1008 |
> |
} |
| 1009 |
> |
} |
| 1010 |
> |
} |
| 1011 |
> |
|
| 1012 |
> |
int n; // worker array size |
| 1013 |
> |
ForkJoinWorkerThread[] ws = p.workers; |
| 1014 |
> |
if (ws != null && (n = ws.length) > 1) { // need at least 2 workers |
| 1015 |
> |
ForkJoinTask<?> task = joinMe; // base of chain |
| 1016 |
> |
ForkJoinWorkerThread thread = this; // thread with stolen task |
| 1017 |
> |
|
| 1018 |
> |
outer:for (int d = 0; d < MAX_HELP_DEPTH; ++d) { // chain length |
| 1019 |
> |
// Try to find v, the stealer of task, by first using hint |
| 1020 |
> |
ForkJoinWorkerThread v = ws[thread.stealHint & (n - 1)]; |
| 1021 |
> |
if (v == null || v.currentSteal != task) { |
| 1022 |
> |
for (int j = 0; ; ++j) { // search array |
| 1023 |
> |
if (j < n) { |
| 1024 |
> |
ForkJoinTask<?> vs; |
| 1025 |
> |
if ((v = ws[j]) != null && |
| 1026 |
> |
(vs = v.currentSteal) != null) { |
| 1027 |
> |
if (joinMe.status < 0) |
| 1028 |
> |
break outer; |
| 1029 |
> |
if (vs == task) { |
| 1030 |
> |
if (task.status < 0) |
| 1031 |
> |
break outer; // stale |
| 1032 |
> |
thread.stealHint = j; |
| 1033 |
> |
break; // save hint for next time |
| 1034 |
> |
} |
| 1035 |
|
} |
| 1036 |
|
} |
| 1037 |
+ |
else |
| 1038 |
+ |
break outer; // no stealer |
| 1039 |
|
} |
| 1025 |
– |
else |
| 1026 |
– |
return; // no stealer |
| 1040 |
|
} |
| 1041 |
< |
} |
| 1042 |
< |
for (;;) { // Try to help v, using specialized form of deqTask |
| 1043 |
< |
if (joinMe.status < 0) |
| 1044 |
< |
return; |
| 1045 |
< |
int b = v.base; |
| 1046 |
< |
ForkJoinTask<?>[] q = v.queue; |
| 1047 |
< |
if (b == v.sp || q == null) |
| 1048 |
< |
break; |
| 1049 |
< |
int i = (q.length - 1) & b; |
| 1050 |
< |
long u = (i << qShift) + qBase; |
| 1051 |
< |
ForkJoinTask<?> t = q[i]; |
| 1052 |
< |
int pid = poolIndex; |
| 1053 |
< |
ForkJoinTask<?> ps = currentSteal; |
| 1054 |
< |
if (task.status < 0) |
| 1055 |
< |
return; // stale or done |
| 1056 |
< |
if (t != null && v.base == b++ && |
| 1057 |
< |
UNSAFE.compareAndSwapObject(q, u, t, null)) { |
| 1058 |
< |
if (joinMe.status < 0) { |
| 1059 |
< |
UNSAFE.putObjectVolatile(q, u, t); |
| 1060 |
< |
return; // back out on cancel |
| 1041 |
> |
|
| 1042 |
> |
// Try to help v, using specialized form of deqTask |
| 1043 |
> |
for (;;) { |
| 1044 |
> |
if (joinMe.status < 0) |
| 1045 |
> |
break outer; |
| 1046 |
> |
int b = v.base; |
| 1047 |
> |
ForkJoinTask<?>[] q = v.queue; |
| 1048 |
> |
if (b == v.sp || q == null) |
| 1049 |
> |
break; // empty |
| 1050 |
> |
int i = (q.length - 1) & b; |
| 1051 |
> |
long u = (i << qShift) + qBase; |
| 1052 |
> |
ForkJoinTask<?> t = q[i]; |
| 1053 |
> |
if (task.status < 0) |
| 1054 |
> |
break outer; // stale |
| 1055 |
> |
if (t != null && |
| 1056 |
> |
(running || |
| 1057 |
> |
(running = p.tryIncrementRunningCount())) && |
| 1058 |
> |
v.base == b++ && |
| 1059 |
> |
UNSAFE.compareAndSwapObject(q, u, t, null)) { |
| 1060 |
> |
if (t != joinMe && joinMe.status < 0) { |
| 1061 |
> |
UNSAFE.putObjectVolatile(q, u, t); |
| 1062 |
> |
break outer; // joinMe cancelled; back out |
| 1063 |
> |
} |
| 1064 |
> |
v.base = b; |
| 1065 |
> |
if (t.status >= 0) { |
| 1066 |
> |
ForkJoinTask<?> ps = currentSteal; |
| 1067 |
> |
int pid = poolIndex; |
| 1068 |
> |
v.stealHint = pid; |
| 1069 |
> |
UNSAFE.putOrderedObject(this, |
| 1070 |
> |
currentStealOffset, t); |
| 1071 |
> |
t.quietlyExec(); |
| 1072 |
> |
UNSAFE.putOrderedObject(this, |
| 1073 |
> |
currentStealOffset, ps); |
| 1074 |
> |
} |
| 1075 |
> |
} |
| 1076 |
> |
else if ((runState & TERMINATING) != 0) { |
| 1077 |
> |
joinMe.cancelIgnoringExceptions(); |
| 1078 |
> |
break outer; |
| 1079 |
|
} |
| 1049 |
– |
v.base = b; |
| 1050 |
– |
v.stealHint = pid; |
| 1051 |
– |
UNSAFE.putOrderedObject(this, currentStealOffset, t); |
| 1052 |
– |
t.quietlyExec(); |
| 1053 |
– |
UNSAFE.putOrderedObject(this, currentStealOffset, ps); |
| 1080 |
|
} |
| 1081 |
+ |
|
| 1082 |
+ |
// Try to descend to find v's stealer |
| 1083 |
+ |
ForkJoinTask<?> next = v.currentJoin; |
| 1084 |
+ |
if (task.status < 0 || next == null || next == task || |
| 1085 |
+ |
joinMe.status < 0) |
| 1086 |
+ |
break; // done, stale, dead-end, or cyclic |
| 1087 |
+ |
task = next; |
| 1088 |
+ |
thread = v; |
| 1089 |
|
} |
| 1056 |
– |
// Try to descend to find v's stealer |
| 1057 |
– |
ForkJoinTask<?> next = v.currentJoin; |
| 1058 |
– |
if (task.status < 0 || next == null || next == task || |
| 1059 |
– |
joinMe.status < 0) |
| 1060 |
– |
return; |
| 1061 |
– |
task = next; |
| 1062 |
– |
thread = v; |
| 1090 |
|
} |
| 1091 |
+ |
return running; |
| 1092 |
|
} |
| 1093 |
|
|
| 1094 |
|
/** |
