5 |
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*/ |
6 |
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7 |
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package jsr166y; |
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import jsr166y.forkjoin.*; |
8 |
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import java.util.concurrent.*; |
9 |
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import java.util.concurrent.atomic.*; |
10 |
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import java.util.concurrent.locks.LockSupport; |
11 |
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import sun.misc.Unsafe; |
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import java.lang.reflect.*; |
13 |
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|
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/** |
15 |
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* A reusable synchronization barrier, similar in functionality to a |
16 |
< |
* {@link java.util.concurrent.CyclicBarrier}, but supporting more |
17 |
< |
* flexible usage. |
16 |
> |
* {@link java.util.concurrent.CyclicBarrier} and {@link |
17 |
> |
* java.util.concurrent.CountDownLatch} but supporting more flexible |
18 |
> |
* usage. |
19 |
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* |
20 |
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* <ul> |
21 |
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* |
22 |
< |
* <li> The number of parties synchronizing on the barrier may vary |
23 |
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* over time. A task may register to be a party in a barrier at any |
24 |
< |
* time, and may deregister upon arriving at the barrier. As is the |
25 |
< |
* case with most basic synchronization constructs, registration |
26 |
< |
* and deregistration affect only internal counts; they do not |
27 |
< |
* establish any further internal bookkeeping, so tasks cannot query |
28 |
< |
* whether they are registered. |
22 |
> |
* <li> The number of parties synchronizing on a phaser may vary over |
23 |
> |
* time. A task may register to be a party at any time, and may |
24 |
> |
* deregister upon arriving at the barrier. As is the case with most |
25 |
> |
* basic synchronization constructs, registration and deregistration |
26 |
> |
* affect only internal counts; they do not establish any further |
27 |
> |
* internal bookkeeping, so tasks cannot query whether they are |
28 |
> |
* registered. (However, you can introduce such bookkeeping in by |
29 |
> |
* subclassing this class.) |
30 |
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* |
31 |
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* <li> Each generation has an associated phase value, starting at |
32 |
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* zero, and advancing when all parties reach the barrier (wrapping |
33 |
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* around to zero after reaching <tt>Integer.MAX_VALUE</tt>). |
34 |
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* |
34 |
> |
* |
35 |
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* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited. |
36 |
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* Method <tt>arriveAndAwaitAdvance</tt> has effect analogous to |
37 |
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* <tt>CyclicBarrier.await</tt>. However, Phasers separate two |
38 |
< |
* aspects of coordination, that may be invoked independently: |
38 |
> |
* aspects of coordination, that may also be invoked independently: |
39 |
|
* |
40 |
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* <ul> |
41 |
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* |
42 |
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* <li> Arriving at a barrier. Methods <tt>arrive</tt> and |
43 |
< |
* <tt>arriveAndDeregister</tt> do not block, but return |
44 |
< |
* the phase value on entry to the method. |
43 |
> |
* <tt>arriveAndDeregister</tt> do not block, but return |
44 |
> |
* the phase value current upon entry to the method. |
45 |
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* |
46 |
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* <li> Awaiting others. Method <tt>awaitAdvance</tt> requires an |
47 |
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* argument indicating the entry phase, and returns when the |
52 |
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* <li> Barrier actions, performed by the task triggering a phase |
53 |
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* advance while others may be waiting, are arranged by overriding |
54 |
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* method <tt>onAdvance</tt>, that also controls termination. |
55 |
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* Overriding this method may be used to similar but more flexible |
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* effect as providing a barrier action to a CyclicBarrier. |
57 |
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* |
58 |
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* <li> Phasers may enter a <em>termination</em> state in which all |
59 |
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* await actions immediately return, indicating (via a negative phase |
60 |
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* value) that execution is complete. Termination is triggered by |
61 |
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* executing the overridable <tt>onAdvance</tt> method that is invoked |
62 |
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* each time the barrier is tripped. When a Phaser is controlling an |
63 |
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* action with a fixed number of iterations, it is often convenient to |
64 |
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* override this method to cause termination when the current phase |
65 |
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* number reaches a threshold. Method <tt>forceTermination</tt> is |
66 |
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* also available to assist recovery actions upon failure. |
67 |
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* |
68 |
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* <li> Unlike most synchronizers, a Phaser may also be used with |
69 |
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* ForkJoinTasks (as well as plain threads). |
70 |
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* |
62 |
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* each time the barrier is about to be tripped. When a Phaser is |
63 |
> |
* controlling an action with a fixed number of iterations, it is |
64 |
> |
* often convenient to override this method to cause termination when |
65 |
> |
* the current phase number reaches a threshold. Method |
66 |
> |
* <tt>forceTermination</tt> is also available to abruptly release |
67 |
> |
* waiting threads and allow them to terminate. |
68 |
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* |
69 |
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* <li> Phasers may be tiered to reduce contention. Phasers with large |
70 |
> |
* numbers of parties that would otherwise experience heavy |
71 |
> |
* synchronization contention costs may instead be arranged in trees. |
72 |
> |
* This will typically greatly increase throughput even though it |
73 |
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* incurs somewhat greater per-operation overhead. |
74 |
> |
* |
75 |
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* <li> By default, <tt>awaitAdvance</tt> continues to wait even if |
76 |
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* the current thread is interrupted. And unlike the case in |
76 |
> |
* the waiting thread is interrupted. And unlike the case in |
77 |
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* CyclicBarriers, exceptions encountered while tasks wait |
78 |
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* interruptibly or with timeout do not change the state of the |
79 |
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* barrier. If necessary, you can perform any associated recovery |
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* within handlers of those exceptions. |
80 |
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* within handlers of those exceptions, often after invoking |
81 |
> |
* <tt>forceTermination</tt>. |
82 |
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* |
83 |
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* </ul> |
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* |
85 |
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* <p><b>Sample usage:</b> |
85 |
> |
* <p><b>Sample usages:</b> |
86 |
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* |
87 |
< |
* <p>[todo: non-FJ example] |
88 |
< |
* |
89 |
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* <p> A Phaser may be used to support a style of programming in |
90 |
< |
* which a task waits for others to complete, without otherwise |
81 |
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* needing to keep track of which tasks it is waiting for. This is |
82 |
< |
* similar to the "sync" construct in Cilk and "clocks" in X10. |
83 |
< |
* Special constructions based on such barriers are available using |
84 |
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* the <tt>LinkedAsyncAction</tt> and <tt>CyclicAction</tt> classes, |
85 |
< |
* but they can be useful in other contexts as well. For a simple |
86 |
< |
* (but not very useful) example, here is a variant of Fibonacci: |
87 |
> |
* <p>A Phaser may be used instead of a <tt>CountdownLatch</tt> to control |
88 |
> |
* a one-shot action serving a variable number of parties. The typical |
89 |
> |
* idiom is for the method setting this up to first register, then |
90 |
> |
* start the actions, then deregister, as in: |
91 |
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* |
92 |
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* <pre> |
93 |
< |
* class BarrierFibonacci extends RecursiveAction { |
94 |
< |
* int argument, result; |
95 |
< |
* final Phaser parentBarrier; |
96 |
< |
* BarrierFibonacci(int n, Phaser parentBarrier) { |
97 |
< |
* this.argument = n; |
98 |
< |
* this.parentBarrier = parentBarrier; |
99 |
< |
* parentBarrier.register(); |
93 |
> |
* void runTasks(List<Runnable> list) { |
94 |
> |
* final Phaser phaser = new Phaser(1); // "1" to register self |
95 |
> |
* for (Runnable r : list) { |
96 |
> |
* phaser.register(); |
97 |
> |
* new Thread() { |
98 |
> |
* public void run() { |
99 |
> |
* phaser.arriveAndAwaitAdvance(); // await all creation |
100 |
> |
* r.run(); |
101 |
> |
* phaser.arriveAndDeregister(); // signal completion |
102 |
> |
* } |
103 |
> |
* }.start(); |
104 |
|
* } |
105 |
< |
* protected void compute() { |
106 |
< |
* int n = argument; |
107 |
< |
* if (n <= 1) |
108 |
< |
* result = n; |
109 |
< |
* else { |
110 |
< |
* Phaser childBarrier = new Phaser(1); |
111 |
< |
* BarrierFibonacci f1 = new BarrierFibonacci(n - 1, childBarrier); |
112 |
< |
* BarrierFibonacci f2 = new BarrierFibonacci(n - 2, childBarrier); |
113 |
< |
* f1.fork(); |
114 |
< |
* f2.fork(); |
115 |
< |
* childBarrier.arriveAndAwait(); |
116 |
< |
* result = f1.result + f2.result; |
117 |
< |
* } |
118 |
< |
* parentBarrier.arriveAndDeregister(); |
105 |
> |
* phaser.arrive(); // allow threads to start |
106 |
> |
* int p = phaser.arriveAndDeregister(); // deregister self |
107 |
> |
* otherActions(); // do other things while tasks execute |
108 |
> |
* phaser.awaitAdvance(p); // wait for all tasks to arrive |
109 |
> |
* } |
110 |
> |
* </pre> |
111 |
> |
* |
112 |
> |
* <p>One way to cause a set of threads to repeatedly perform actions |
113 |
> |
* for a given number of iterations is to override <tt>onAdvance</tt>: |
114 |
> |
* |
115 |
> |
* <pre> |
116 |
> |
* void startTasks(List<Runnable> list, final int iterations) { |
117 |
> |
* final Phaser phaser = new Phaser() { |
118 |
> |
* public boolean onAdvance(int phase, int registeredParties) { |
119 |
> |
* return phase >= iterations || registeredParties == 0; |
120 |
> |
* } |
121 |
> |
* }; |
122 |
> |
* phaser.register(); |
123 |
> |
* for (Runnable r : list) { |
124 |
> |
* phaser.register(); |
125 |
> |
* new Thread() { |
126 |
> |
* public void run() { |
127 |
> |
* do { |
128 |
> |
* r.run(); |
129 |
> |
* phaser.arriveAndAwaitAdvance(); |
130 |
> |
* } while(!phaser.isTerminated(); |
131 |
> |
* } |
132 |
> |
* }.start(); |
133 |
|
* } |
134 |
+ |
* phaser.arriveAndDeregister(); // deregister self, don't wait |
135 |
|
* } |
136 |
|
* </pre> |
137 |
|
* |
138 |
+ |
* <p> To create a set of tasks using a tree of Phasers, |
139 |
+ |
* you could use code of the following form, assuming a |
140 |
+ |
* Task class with a constructor accepting a Phaser that |
141 |
+ |
* it registers for upon construction: |
142 |
+ |
* <pre> |
143 |
+ |
* void build(Task[] actions, int lo, int hi, Phaser b) { |
144 |
+ |
* int step = (hi - lo) / TASKS_PER_PHASER; |
145 |
+ |
* if (step > 1) { |
146 |
+ |
* int i = lo; |
147 |
+ |
* while (i < hi) { |
148 |
+ |
* int r = Math.min(i + step, hi); |
149 |
+ |
* build(actions, i, r, new Phaser(b)); |
150 |
+ |
* i = r; |
151 |
+ |
* } |
152 |
+ |
* } |
153 |
+ |
* else { |
154 |
+ |
* for (int i = lo; i < hi; ++i) |
155 |
+ |
* actions[i] = new Task(b); |
156 |
+ |
* // assumes new Task(b) performs b.register() |
157 |
+ |
* } |
158 |
+ |
* } |
159 |
+ |
* // .. initially called, for n tasks via |
160 |
+ |
* build(new Task[n], 0, n, new Phaser()); |
161 |
+ |
* </pre> |
162 |
+ |
* |
163 |
+ |
* The best value of <tt>TASKS_PER_PHASER</tt> depends mainly on |
164 |
+ |
* expected barrier synchronization rates. A value as low as four may |
165 |
+ |
* be appropriate for extremely small per-barrier task bodies (thus |
166 |
+ |
* high rates), or up to hundreds for extremely large ones. |
167 |
+ |
* |
168 |
+ |
* </pre> |
169 |
+ |
* |
170 |
|
* <p><b>Implementation notes</b>: This implementation restricts the |
171 |
< |
* maximum number of parties to 65535. Attempts to register |
172 |
< |
* additional parties result in IllegalStateExceptions. |
171 |
> |
* maximum number of parties to 65535. Attempts to register additional |
172 |
> |
* parties result in IllegalStateExceptions. However, you can and |
173 |
> |
* should create tiered phasers to accommodate arbitrarily large sets |
174 |
> |
* of participants. |
175 |
|
*/ |
176 |
|
public class Phaser { |
177 |
|
/* |
178 |
|
* This class implements an extension of X10 "clocks". Thanks to |
179 |
< |
* Vijay Saraswat for the idea of applying it to ForkJoinTasks, |
180 |
< |
* and to Vivek Sarkar for enhancements to extend functionality. |
179 |
> |
* Vijay Saraswat for the idea, and to Vivek Sarkar for |
180 |
> |
* enhancements to extend functionality. |
181 |
|
*/ |
182 |
|
|
183 |
|
/** |
184 |
|
* Barrier state representation. Conceptually, a barrier contains |
185 |
|
* four values: |
186 |
< |
* |
186 |
> |
* |
187 |
|
* * parties -- the number of parties to wait (16 bits) |
188 |
|
* * unarrived -- the number of parties yet to hit barrier (16 bits) |
189 |
|
* * phase -- the generation of the barrier (31 bits) |
190 |
|
* * terminated -- set if barrier is terminated (1 bit) |
191 |
|
* |
192 |
|
* However, to efficiently maintain atomicity, these values are |
193 |
< |
* packed into a single AtomicLong. Termination uses the sign bit |
194 |
< |
* of 32 bit representation of phase, so phase is set to -1 on |
195 |
< |
* termination. |
196 |
< |
*/ |
197 |
< |
private final AtomicLong state; |
198 |
< |
|
199 |
< |
/** |
143 |
< |
* Head of Treiber stack for waiting nonFJ threads. |
193 |
> |
* packed into a single (atomic) long. Termination uses the sign |
194 |
> |
* bit of 32 bit representation of phase, so phase is set to -1 on |
195 |
> |
* termination. Good performace relies on keeping state decoding |
196 |
> |
* and encoding simple, and keeping race windows short. |
197 |
> |
* |
198 |
> |
* Note: there are some cheats in arrive() that rely on unarrived |
199 |
> |
* being lowest 16 bits. |
200 |
|
*/ |
201 |
< |
private final AtomicReference<QNode> head = new AtomicReference<QNode>(); |
201 |
> |
private volatile long state; |
202 |
|
|
203 |
|
private static final int ushortBits = 16; |
204 |
|
private static final int ushortMask = (1 << ushortBits) - 1; |
224 |
|
return (((long)phase) << 32) | ((parties << 16) | unarrived); |
225 |
|
} |
226 |
|
|
227 |
+ |
private static long trippedStateFor(int phase, int parties) { |
228 |
+ |
return (((long)phase) << 32) | ((parties << 16) | parties); |
229 |
+ |
} |
230 |
+ |
|
231 |
|
private static IllegalStateException badBounds(int parties, int unarrived) { |
232 |
< |
return new IllegalStateException("Attempt to set " + unarrived + |
233 |
< |
" unarrived of " + parties + " parties"); |
232 |
> |
return new IllegalStateException |
233 |
> |
("Attempt to set " + unarrived + |
234 |
> |
" unarrived of " + parties + " parties"); |
235 |
> |
} |
236 |
> |
|
237 |
> |
/** |
238 |
> |
* The parent of this phaser, or null if none |
239 |
> |
*/ |
240 |
> |
private final Phaser parent; |
241 |
> |
|
242 |
> |
/** |
243 |
> |
* The root of Phaser tree. Equals this if not in a tree. Used to |
244 |
> |
* support faster state push-down. |
245 |
> |
*/ |
246 |
> |
private final Phaser root; |
247 |
> |
|
248 |
> |
// Wait queues |
249 |
> |
|
250 |
> |
/** |
251 |
> |
* Heads of Treiber stacks waiting for nonFJ threads. To eliminate |
252 |
> |
* contention while releasing some threads while adding others, we |
253 |
> |
* use two of them, alternating across even and odd phases. |
254 |
> |
*/ |
255 |
> |
private final AtomicReference<QNode> evenQ = new AtomicReference<QNode>(); |
256 |
> |
private final AtomicReference<QNode> oddQ = new AtomicReference<QNode>(); |
257 |
> |
|
258 |
> |
private AtomicReference<QNode> queueFor(int phase) { |
259 |
> |
return (phase & 1) == 0? evenQ : oddQ; |
260 |
> |
} |
261 |
> |
|
262 |
> |
/** |
263 |
> |
* Returns current state, first resolving lagged propagation from |
264 |
> |
* root if necessary. |
265 |
> |
*/ |
266 |
> |
private long getReconciledState() { |
267 |
> |
return parent == null? state : reconcileState(); |
268 |
> |
} |
269 |
> |
|
270 |
> |
/** |
271 |
> |
* Recursively resolves state. |
272 |
> |
*/ |
273 |
> |
private long reconcileState() { |
274 |
> |
Phaser p = parent; |
275 |
> |
long s = state; |
276 |
> |
if (p != null) { |
277 |
> |
while (unarrivedOf(s) == 0 && phaseOf(s) != phaseOf(root.state)) { |
278 |
> |
long parentState = p.getReconciledState(); |
279 |
> |
int parentPhase = phaseOf(parentState); |
280 |
> |
int phase = phaseOf(s = state); |
281 |
> |
if (phase != parentPhase) { |
282 |
> |
long next = trippedStateFor(parentPhase, partiesOf(s)); |
283 |
> |
if (casState(s, next)) { |
284 |
> |
releaseWaiters(phase); |
285 |
> |
s = next; |
286 |
> |
} |
287 |
> |
} |
288 |
> |
} |
289 |
> |
} |
290 |
> |
return s; |
291 |
|
} |
292 |
|
|
293 |
|
/** |
294 |
|
* Creates a new Phaser without any initially registered parties, |
295 |
< |
* and initial phase number 0. |
295 |
> |
* initial phase number 0, and no parent. |
296 |
|
*/ |
297 |
|
public Phaser() { |
298 |
< |
state = new AtomicLong(stateFor(0, 0, 0)); |
298 |
> |
this(null); |
299 |
|
} |
300 |
|
|
301 |
|
/** |
302 |
|
* Creates a new Phaser with the given numbers of registered |
303 |
< |
* unarrived parties and initial phase number 0. |
303 |
> |
* unarrived parties, initial phase number 0, and no parent. |
304 |
|
* @param parties the number of parties required to trip barrier. |
305 |
|
* @throws IllegalArgumentException if parties less than zero |
306 |
|
* or greater than the maximum number of parties supported. |
307 |
|
*/ |
308 |
|
public Phaser(int parties) { |
309 |
+ |
this(null, parties); |
310 |
+ |
} |
311 |
+ |
|
312 |
+ |
/** |
313 |
+ |
* Creates a new Phaser with the given parent, without any |
314 |
+ |
* initially registered parties. If parent is non-null this phaser |
315 |
+ |
* is registered with the parent and its initial phase number is |
316 |
+ |
* the same as that of parent phaser. |
317 |
+ |
* @param parent the parent phaser. |
318 |
+ |
*/ |
319 |
+ |
public Phaser(Phaser parent) { |
320 |
+ |
int phase = 0; |
321 |
+ |
this.parent = parent; |
322 |
+ |
if (parent != null) { |
323 |
+ |
this.root = parent.root; |
324 |
+ |
phase = parent.register(); |
325 |
+ |
} |
326 |
+ |
else |
327 |
+ |
this.root = this; |
328 |
+ |
this.state = trippedStateFor(phase, 0); |
329 |
+ |
} |
330 |
+ |
|
331 |
+ |
/** |
332 |
+ |
* Creates a new Phaser with the given parent and numbers of |
333 |
+ |
* registered unarrived parties. If parent is non-null this phaser |
334 |
+ |
* is registered with the parent and its initial phase number is |
335 |
+ |
* the same as that of parent phaser. |
336 |
+ |
* @param parent the parent phaser. |
337 |
+ |
* @param parties the number of parties required to trip barrier. |
338 |
+ |
* @throws IllegalArgumentException if parties less than zero |
339 |
+ |
* or greater than the maximum number of parties supported. |
340 |
+ |
*/ |
341 |
+ |
public Phaser(Phaser parent, int parties) { |
342 |
|
if (parties < 0 || parties > ushortMask) |
343 |
|
throw new IllegalArgumentException("Illegal number of parties"); |
344 |
< |
state = new AtomicLong(stateFor(0, parties, parties)); |
344 |
> |
int phase = 0; |
345 |
> |
this.parent = parent; |
346 |
> |
if (parent != null) { |
347 |
> |
this.root = parent.root; |
348 |
> |
phase = parent.register(); |
349 |
> |
} |
350 |
> |
else |
351 |
> |
this.root = this; |
352 |
> |
this.state = trippedStateFor(phase, parties); |
353 |
|
} |
354 |
|
|
355 |
|
/** |
358 |
|
* @throws IllegalStateException if attempting to register more |
359 |
|
* than the maximum supported number of parties. |
360 |
|
*/ |
361 |
< |
public int register() { // increment both parties and unarrived |
362 |
< |
final AtomicLong state = this.state; |
361 |
> |
public int register() { |
362 |
> |
return doRegister(1); |
363 |
> |
} |
364 |
> |
|
365 |
> |
/** |
366 |
> |
* Adds the given number of new unarrived parties to this phaser. |
367 |
> |
* @param parties the number of parties required to trip barrier. |
368 |
> |
* @return the current barrier phase number upon registration |
369 |
> |
* @throws IllegalStateException if attempting to register more |
370 |
> |
* than the maximum supported number of parties. |
371 |
> |
*/ |
372 |
> |
public int bulkRegister(int parties) { |
373 |
> |
if (parties < 0) |
374 |
> |
throw new IllegalArgumentException(); |
375 |
> |
if (parties == 0) |
376 |
> |
return getPhase(); |
377 |
> |
return doRegister(parties); |
378 |
> |
} |
379 |
> |
|
380 |
> |
/** |
381 |
> |
* Shared code for register, bulkRegister |
382 |
> |
*/ |
383 |
> |
private int doRegister(int registrations) { |
384 |
> |
int phase; |
385 |
|
for (;;) { |
386 |
< |
long s = state.get(); |
387 |
< |
int phase = phaseOf(s); |
388 |
< |
int parties = partiesOf(s) + 1; |
389 |
< |
int unarrived = unarrivedOf(s) + 1; |
386 |
> |
long s = getReconciledState(); |
387 |
> |
phase = phaseOf(s); |
388 |
> |
int unarrived = unarrivedOf(s) + registrations; |
389 |
> |
int parties = partiesOf(s) + registrations; |
390 |
> |
if (phase < 0) |
391 |
> |
break; |
392 |
|
if (parties > ushortMask || unarrived > ushortMask) |
393 |
|
throw badBounds(parties, unarrived); |
394 |
< |
if (state.compareAndSet(s, stateFor(phase, parties, unarrived))) |
395 |
< |
return phase; |
394 |
> |
if (phase == phaseOf(root.state) && |
395 |
> |
casState(s, stateFor(phase, parties, unarrived))) |
396 |
> |
break; |
397 |
|
} |
398 |
+ |
return phase; |
399 |
|
} |
400 |
|
|
401 |
|
/** |
402 |
|
* Arrives at the barrier, but does not wait for others. (You can |
403 |
|
* in turn wait for others via {@link #awaitAdvance}). |
404 |
|
* |
405 |
< |
* @return the current barrier phase number upon entry to |
406 |
< |
* this method, or a negative value if terminated; |
407 |
< |
* @throws IllegalStateException if the number of unarrived |
408 |
< |
* parties would become negative. |
405 |
> |
* @return the barrier phase number upon entry to this method, or a |
406 |
> |
* negative value if terminated; |
407 |
> |
* @throws IllegalStateException if not terminated and the number |
408 |
> |
* of unarrived parties would become negative. |
409 |
|
*/ |
410 |
< |
public int arrive() { // decrement unarrived. If zero, trip |
411 |
< |
final AtomicLong state = this.state; |
410 |
> |
public int arrive() { |
411 |
> |
int phase; |
412 |
|
for (;;) { |
413 |
< |
long s = state.get(); |
414 |
< |
int phase = phaseOf(s); |
413 |
> |
long s = state; |
414 |
> |
phase = phaseOf(s); |
415 |
|
int parties = partiesOf(s); |
416 |
|
int unarrived = unarrivedOf(s) - 1; |
417 |
< |
if (unarrived < 0) |
418 |
< |
throw badBounds(parties, unarrived); |
419 |
< |
if (unarrived == 0 && phase >= 0) { |
420 |
< |
trip(phase, parties); |
421 |
< |
return phase; |
417 |
> |
if (unarrived > 0) { // Not the last arrival |
418 |
> |
if (casState(s, s - 1)) // s-1 adds one arrival |
419 |
> |
break; |
420 |
> |
} |
421 |
> |
else if (unarrived == 0) { // the last arrival |
422 |
> |
Phaser par = parent; |
423 |
> |
if (par == null) { // directly trip |
424 |
> |
if (casState |
425 |
> |
(s, |
426 |
> |
trippedStateFor(onAdvance(phase, parties)? -1 : |
427 |
> |
((phase + 1) & phaseMask), parties))) { |
428 |
> |
releaseWaiters(phase); |
429 |
> |
break; |
430 |
> |
} |
431 |
> |
} |
432 |
> |
else { // cascade to parent |
433 |
> |
if (casState(s, s - 1)) { // zeroes unarrived |
434 |
> |
par.arrive(); |
435 |
> |
reconcileState(); |
436 |
> |
break; |
437 |
> |
} |
438 |
> |
} |
439 |
|
} |
440 |
< |
if (state.compareAndSet(s, stateFor(phase, parties, unarrived))) |
441 |
< |
return phase; |
440 |
> |
else if (phase < 0) // Don't throw exception if terminated |
441 |
> |
break; |
442 |
> |
else if (phase != phaseOf(root.state)) // or if unreconciled |
443 |
> |
reconcileState(); |
444 |
> |
else |
445 |
> |
throw badBounds(parties, unarrived); |
446 |
|
} |
447 |
+ |
return phase; |
448 |
|
} |
449 |
|
|
450 |
|
/** |
451 |
|
* Arrives at the barrier, and deregisters from it, without |
452 |
< |
* waiting for others. |
452 |
> |
* waiting for others. Deregistration reduces number of parties |
453 |
> |
* required to trip the barrier in future phases. If this phaser |
454 |
> |
* has a parent, and deregistration causes this phaser to have |
455 |
> |
* zero parties, this phaser is also deregistered from its parent. |
456 |
|
* |
457 |
|
* @return the current barrier phase number upon entry to |
458 |
|
* this method, or a negative value if terminated; |
459 |
< |
* @throws IllegalStateException if the number of registered or |
460 |
< |
* unarrived parties would become negative. |
459 |
> |
* @throws IllegalStateException if not terminated and the number |
460 |
> |
* of registered or unarrived parties would become negative. |
461 |
|
*/ |
462 |
< |
public int arriveAndDeregister() { // Same as arrive, plus decrement parties |
463 |
< |
final AtomicLong state = this.state; |
462 |
> |
public int arriveAndDeregister() { |
463 |
> |
// similar code to arrive, but too different to merge |
464 |
> |
Phaser par = parent; |
465 |
> |
int phase; |
466 |
|
for (;;) { |
467 |
< |
long s = state.get(); |
468 |
< |
int phase = phaseOf(s); |
467 |
> |
long s = state; |
468 |
> |
phase = phaseOf(s); |
469 |
|
int parties = partiesOf(s) - 1; |
470 |
|
int unarrived = unarrivedOf(s) - 1; |
471 |
< |
if (parties < 0 || unarrived < 0) |
472 |
< |
throw badBounds(parties, unarrived); |
473 |
< |
if (unarrived == 0 && phase >= 0) { |
474 |
< |
trip(phase, parties); |
475 |
< |
return phase; |
471 |
> |
if (parties >= 0) { |
472 |
> |
if (unarrived > 0 || (unarrived == 0 && par != null)) { |
473 |
> |
if (casState |
474 |
> |
(s, |
475 |
> |
stateFor(phase, parties, unarrived))) { |
476 |
> |
if (unarrived == 0) { |
477 |
> |
par.arriveAndDeregister(); |
478 |
> |
reconcileState(); |
479 |
> |
} |
480 |
> |
break; |
481 |
> |
} |
482 |
> |
continue; |
483 |
> |
} |
484 |
> |
if (unarrived == 0) { |
485 |
> |
if (casState |
486 |
> |
(s, |
487 |
> |
trippedStateFor(onAdvance(phase, parties)? -1 : |
488 |
> |
((phase + 1) & phaseMask), parties))) { |
489 |
> |
releaseWaiters(phase); |
490 |
> |
break; |
491 |
> |
} |
492 |
> |
continue; |
493 |
> |
} |
494 |
> |
if (phase < 0) |
495 |
> |
break; |
496 |
> |
if (par != null && phase != phaseOf(root.state)) { |
497 |
> |
reconcileState(); |
498 |
> |
continue; |
499 |
> |
} |
500 |
|
} |
501 |
< |
if (state.compareAndSet(s, stateFor(phase, parties, unarrived))) |
267 |
< |
return phase; |
501 |
> |
throw badBounds(parties, unarrived); |
502 |
|
} |
503 |
+ |
return phase; |
504 |
|
} |
505 |
|
|
506 |
|
/** |
507 |
< |
* Arrives at the barrier and awaits others. Unlike other arrival |
508 |
< |
* methods, this method returns the arrival index of the |
509 |
< |
* caller. The caller tripping the barrier returns zero, the |
510 |
< |
* previous caller 1, and so on. |
511 |
< |
* @return the arrival index |
512 |
< |
* @throws IllegalStateException if the number of unarrived |
513 |
< |
* parties would become negative. |
507 |
> |
* Arrives at the barrier and awaits others. Equivalent in effect |
508 |
> |
* to <tt>awaitAdvance(arrive())</tt>. If you instead need to |
509 |
> |
* await with interruption of timeout, and/or deregister upon |
510 |
> |
* arrival, you can arrange them using analogous constructions. |
511 |
> |
* @return the phase on entry to this method |
512 |
> |
* @throws IllegalStateException if not terminated and the number |
513 |
> |
* of unarrived parties would become negative. |
514 |
|
*/ |
515 |
|
public int arriveAndAwaitAdvance() { |
516 |
< |
final AtomicLong state = this.state; |
282 |
< |
for (;;) { |
283 |
< |
long s = state.get(); |
284 |
< |
int phase = phaseOf(s); |
285 |
< |
int parties = partiesOf(s); |
286 |
< |
int unarrived = unarrivedOf(s) - 1; |
287 |
< |
if (unarrived < 0) |
288 |
< |
throw badBounds(parties, unarrived); |
289 |
< |
if (unarrived == 0 && phase >= 0) { |
290 |
< |
trip(phase, parties); |
291 |
< |
return 0; |
292 |
< |
} |
293 |
< |
if (state.compareAndSet(s, stateFor(phase, parties, unarrived))) { |
294 |
< |
awaitAdvance(phase); |
295 |
< |
return unarrived; |
296 |
< |
} |
297 |
< |
} |
516 |
> |
return awaitAdvance(arrive()); |
517 |
|
} |
518 |
|
|
519 |
|
/** |
520 |
|
* Awaits the phase of the barrier to advance from the given |
521 |
< |
* value, or returns immediately if this barrier is terminated |
521 |
> |
* value, or returns immediately if argument is negative or this |
522 |
> |
* barrier is terminated. |
523 |
|
* @param phase the phase on entry to this method |
524 |
|
* @return the phase on exit from this method |
525 |
|
*/ |
526 |
|
public int awaitAdvance(int phase) { |
527 |
|
if (phase < 0) |
528 |
|
return phase; |
529 |
< |
Thread current = Thread.currentThread(); |
530 |
< |
if (current instanceof ForkJoinWorkerThread) |
531 |
< |
return helpingWait(phase); |
532 |
< |
if (untimedWait(current, phase, false)) |
533 |
< |
current.interrupt(); |
534 |
< |
return phaseOf(state.get()); |
529 |
> |
long s = getReconciledState(); |
530 |
> |
int p = phaseOf(s); |
531 |
> |
if (p != phase) |
532 |
> |
return p; |
533 |
> |
if (unarrivedOf(s) == 0) |
534 |
> |
parent.awaitAdvance(phase); |
535 |
> |
// Fall here even if parent waited, to reconcile and help release |
536 |
> |
return untimedWait(phase); |
537 |
|
} |
538 |
|
|
539 |
|
/** |
540 |
|
* Awaits the phase of the barrier to advance from the given |
541 |
< |
* value, or returns immediately if this barrier is terminated, or |
542 |
< |
* throws InterruptedException if interrupted while waiting. |
541 |
> |
* value, or returns immediately if argumet is negative or this |
542 |
> |
* barrier is terminated, or throws InterruptedException if |
543 |
> |
* interrupted while waiting. |
544 |
|
* @param phase the phase on entry to this method |
545 |
|
* @return the phase on exit from this method |
546 |
|
* @throws InterruptedException if thread interrupted while waiting |
548 |
|
public int awaitAdvanceInterruptibly(int phase) throws InterruptedException { |
549 |
|
if (phase < 0) |
550 |
|
return phase; |
551 |
< |
Thread current = Thread.currentThread(); |
552 |
< |
if (current instanceof ForkJoinWorkerThread) |
553 |
< |
return helpingWait(phase); |
554 |
< |
else if (Thread.interrupted() || untimedWait(current, phase, true)) |
555 |
< |
throw new InterruptedException(); |
556 |
< |
else |
557 |
< |
return phaseOf(state.get()); |
551 |
> |
long s = getReconciledState(); |
552 |
> |
int p = phaseOf(s); |
553 |
> |
if (p != phase) |
554 |
> |
return p; |
555 |
> |
if (unarrivedOf(s) != 0) |
556 |
> |
parent.awaitAdvanceInterruptibly(phase); |
557 |
> |
return interruptibleWait(phase); |
558 |
|
} |
559 |
|
|
560 |
|
/** |
561 |
|
* Awaits the phase of the barrier to advance from the given value |
562 |
< |
* or the given timeout elapses, or returns immediately if this |
563 |
< |
* barrier is terminated |
562 |
> |
* or the given timeout elapses, or returns immediately if |
563 |
> |
* argument is negative or this barrier is terminated. |
564 |
|
* @param phase the phase on entry to this method |
565 |
|
* @return the phase on exit from this method |
566 |
|
* @throws InterruptedException if thread interrupted while waiting |
567 |
|
* @throws TimeoutException if timed out while waiting |
568 |
|
*/ |
569 |
< |
public int awaitAdvanceInterruptibly(int phase, long timeout, TimeUnit unit) |
569 |
> |
public int awaitAdvanceInterruptibly(int phase, long timeout, TimeUnit unit) |
570 |
|
throws InterruptedException, TimeoutException { |
571 |
|
if (phase < 0) |
572 |
|
return phase; |
573 |
< |
long nanos = unit.toNanos(timeout); |
574 |
< |
Thread current = Thread.currentThread(); |
575 |
< |
if (current instanceof ForkJoinWorkerThread) |
576 |
< |
return timedHelpingWait(phase, nanos); |
577 |
< |
timedWait(current, phase, nanos); |
578 |
< |
return phaseOf(state.get()); |
573 |
> |
long s = getReconciledState(); |
574 |
> |
int p = phaseOf(s); |
575 |
> |
if (p != phase) |
576 |
> |
return p; |
577 |
> |
if (unarrivedOf(s) == 0) |
578 |
> |
parent.awaitAdvanceInterruptibly(phase, timeout, unit); |
579 |
> |
return timedWait(phase, unit.toNanos(timeout)); |
580 |
|
} |
581 |
|
|
582 |
|
/** |
583 |
|
* Forces this barrier to enter termination state. Counts of |
584 |
< |
* arrived and registered parties are unaffected. This method may |
585 |
< |
* be useful for coordinating recovery after one or more tasks |
586 |
< |
* encounter unexpected exceptions. |
584 |
> |
* arrived and registered parties are unaffected. If this phaser |
585 |
> |
* has a parent, it too is terminated. This method may be useful |
586 |
> |
* for coordinating recovery after one or more tasks encounter |
587 |
> |
* unexpected exceptions. |
588 |
|
*/ |
589 |
|
public void forceTermination() { |
365 |
– |
final AtomicLong state = this.state; |
590 |
|
for (;;) { |
591 |
< |
long s = state.get(); |
591 |
> |
long s = getReconciledState(); |
592 |
|
int phase = phaseOf(s); |
593 |
|
int parties = partiesOf(s); |
594 |
|
int unarrived = unarrivedOf(s); |
595 |
|
if (phase < 0 || |
596 |
< |
state.compareAndSet(s, stateFor(-1, parties, unarrived))) { |
597 |
< |
if (head.get() != null) |
598 |
< |
releaseWaiters(-1); |
596 |
> |
casState(s, stateFor(-1, parties, unarrived))) { |
597 |
> |
releaseWaiters(0); |
598 |
> |
releaseWaiters(1); |
599 |
> |
if (parent != null) |
600 |
> |
parent.forceTermination(); |
601 |
|
return; |
602 |
|
} |
603 |
|
} |
604 |
|
} |
605 |
|
|
606 |
|
/** |
381 |
– |
* Resets the barrier with the given numbers of registered unarrived |
382 |
– |
* parties and phase number 0. This method allows repeated reuse |
383 |
– |
* of this barrier, but only if it is somehow known not to be in |
384 |
– |
* use for other purposes. |
385 |
– |
* @param parties the number of parties required to trip barrier. |
386 |
– |
* @throws IllegalArgumentException if parties less than zero |
387 |
– |
* or greater than the maximum number of parties supported. |
388 |
– |
*/ |
389 |
– |
public void reset(int parties) { |
390 |
– |
if (parties < 0 || parties > ushortMask) |
391 |
– |
throw new IllegalArgumentException("Illegal number of parties"); |
392 |
– |
state.set(stateFor(0, parties, parties)); |
393 |
– |
if (head.get() != null) |
394 |
– |
releaseWaiters(0); |
395 |
– |
} |
396 |
– |
|
397 |
– |
/** |
607 |
|
* Returns the current phase number. The maximum phase number is |
608 |
|
* <tt>Integer.MAX_VALUE</tt>, after which it restarts at |
609 |
|
* zero. Upon termination, the phase number is negative. |
610 |
|
* @return the phase number, or a negative value if terminated |
611 |
|
*/ |
612 |
< |
public int getPhase() { |
613 |
< |
return phaseOf(state.get()); |
612 |
> |
public final int getPhase() { |
613 |
> |
return phaseOf(getReconciledState()); |
614 |
> |
} |
615 |
> |
|
616 |
> |
/** |
617 |
> |
* Returns true if the current phase number equals the given phase. |
618 |
> |
* @param phase the phase |
619 |
> |
* @return true if the current phase number equals the given phase. |
620 |
> |
*/ |
621 |
> |
public final boolean hasPhase(int phase) { |
622 |
> |
return phaseOf(getReconciledState()) == phase; |
623 |
|
} |
624 |
|
|
625 |
|
/** |
627 |
|
* @return the number of parties |
628 |
|
*/ |
629 |
|
public int getRegisteredParties() { |
630 |
< |
return partiesOf(state.get()); |
630 |
> |
return partiesOf(state); |
631 |
|
} |
632 |
|
|
633 |
|
/** |
636 |
|
* @return the number of arrived parties |
637 |
|
*/ |
638 |
|
public int getArrivedParties() { |
639 |
< |
return arrivedOf(state.get()); |
639 |
> |
return arrivedOf(state); |
640 |
|
} |
641 |
|
|
642 |
|
/** |
645 |
|
* @return the number of unarrived parties |
646 |
|
*/ |
647 |
|
public int getUnarrivedParties() { |
648 |
< |
return unarrivedOf(state.get()); |
648 |
> |
return unarrivedOf(state); |
649 |
> |
} |
650 |
> |
|
651 |
> |
/** |
652 |
> |
* Returns the parent of this phaser, or null if none. |
653 |
> |
* @return the parent of this phaser, or null if none. |
654 |
> |
*/ |
655 |
> |
public Phaser getParent() { |
656 |
> |
return parent; |
657 |
|
} |
658 |
|
|
659 |
|
/** |
660 |
< |
* Returns true if this barrier has been terminated |
660 |
> |
* Returns the root ancestor of this phaser, which is the same as |
661 |
> |
* this phaser if it has no parent. |
662 |
> |
* @return the root ancestor of this phaser. |
663 |
> |
*/ |
664 |
> |
public Phaser getRoot() { |
665 |
> |
return root; |
666 |
> |
} |
667 |
> |
|
668 |
> |
/** |
669 |
> |
* Returns true if this barrier has been terminated. |
670 |
|
* @return true if this barrier has been terminated |
671 |
|
*/ |
672 |
|
public boolean isTerminated() { |
673 |
< |
return phaseOf(state.get()) < 0; |
673 |
> |
return getPhase() < 0; |
674 |
|
} |
675 |
|
|
676 |
|
/** |
681 |
|
* phase number, this barrier will be set to a final termination |
682 |
|
* state, and subsequent calls to <tt>isTerminated</tt> will |
683 |
|
* return true. |
684 |
< |
* |
684 |
> |
* |
685 |
|
* <p> The default version returns true when the number of |
686 |
|
* registered parties is zero. Normally, overrides that arrange |
687 |
|
* termination for other reasons should also preserve this |
688 |
|
* property. |
689 |
|
* |
690 |
+ |
* <p> You may override this method to perform an action with side |
691 |
+ |
* effects visible to participating tasks, but it is in general |
692 |
+ |
* only sensible to do so in designs where all parties register |
693 |
+ |
* before any arrive, and all <tt>awaitAdvance</tt> at each phase. |
694 |
+ |
* Otherwise, you cannot ensure lack of interference. In |
695 |
+ |
* particular, this method may be invoked more than once per |
696 |
+ |
* transition if other parties successfully register while the |
697 |
+ |
* invocation of this method is in progress, thus postponing the |
698 |
+ |
* transition until those parties also arrive, re-triggering this |
699 |
+ |
* method. |
700 |
+ |
* |
701 |
|
* @param phase the phase number on entering the barrier |
702 |
|
* @param registeredParties the current number of registered |
703 |
|
* parties. |
708 |
|
} |
709 |
|
|
710 |
|
/** |
711 |
< |
* Returns a string identifying this barrier, as well as its |
711 |
> |
* Returns a string identifying this phaser, as well as its |
712 |
|
* state. The state, in brackets, includes the String {@code |
713 |
|
* "phase ="} followed by the phase number, {@code "parties ="} |
714 |
|
* followed by the number of registered parties, and {@code |
717 |
|
* @return a string identifying this barrier, as well as its state |
718 |
|
*/ |
719 |
|
public String toString() { |
720 |
< |
long s = state.get(); |
720 |
> |
long s = getReconciledState(); |
721 |
|
return super.toString() + "[phase = " + phaseOf(s) + " parties = " + partiesOf(s) + " arrived = " + arrivedOf(s) + "]"; |
722 |
|
} |
723 |
|
|
724 |
< |
// methods for tripping and waiting |
479 |
< |
|
480 |
< |
/** |
481 |
< |
* Advance the current phase (or terminate) |
482 |
< |
*/ |
483 |
< |
private void trip(int phase, int parties) { |
484 |
< |
int next = onAdvance(phase, parties)? -1 : ((phase + 1) & phaseMask); |
485 |
< |
state.set(stateFor(next, parties, parties)); |
486 |
< |
if (head.get() != null) |
487 |
< |
releaseWaiters(next); |
488 |
< |
} |
489 |
< |
|
490 |
< |
private int helpingWait(int phase) { |
491 |
< |
final AtomicLong state = this.state; |
492 |
< |
int p; |
493 |
< |
while ((p = phaseOf(state.get())) == phase) { |
494 |
< |
ForkJoinTask<?> t = ForkJoinWorkerThread.pollTask(); |
495 |
< |
if (t != null) { |
496 |
< |
if ((p = phaseOf(state.get())) == phase) |
497 |
< |
t.exec(); |
498 |
< |
else { // push task and exit if barrier advanced |
499 |
< |
t.fork(); |
500 |
< |
break; |
501 |
< |
} |
502 |
< |
} |
503 |
< |
} |
504 |
< |
return p; |
505 |
< |
} |
506 |
< |
|
507 |
< |
private int timedHelpingWait(int phase, long nanos) throws TimeoutException { |
508 |
< |
final AtomicLong state = this.state; |
509 |
< |
long lastTime = System.nanoTime(); |
510 |
< |
int p; |
511 |
< |
while ((p = phaseOf(state.get())) == phase) { |
512 |
< |
long now = System.nanoTime(); |
513 |
< |
nanos -= now - lastTime; |
514 |
< |
lastTime = now; |
515 |
< |
if (nanos <= 0) { |
516 |
< |
if ((p = phaseOf(state.get())) == phase) |
517 |
< |
throw new TimeoutException(); |
518 |
< |
else |
519 |
< |
break; |
520 |
< |
} |
521 |
< |
ForkJoinTask<?> t = ForkJoinWorkerThread.pollTask(); |
522 |
< |
if (t != null) { |
523 |
< |
if ((p = phaseOf(state.get())) == phase) |
524 |
< |
t.exec(); |
525 |
< |
else { // push task and exit if barrier advanced |
526 |
< |
t.fork(); |
527 |
< |
break; |
528 |
< |
} |
529 |
< |
} |
530 |
< |
} |
531 |
< |
return p; |
532 |
< |
} |
533 |
< |
|
534 |
< |
/** |
535 |
< |
* Wait nodes for Treiber stack representing wait queue for non-FJ |
536 |
< |
* tasks. The waiting scheme is an adaptation of the one used in |
537 |
< |
* forkjoin.PoolBarrier. |
538 |
< |
*/ |
539 |
< |
static final class QNode { |
540 |
< |
QNode next; |
541 |
< |
volatile Thread thread; // nulled to cancel wait |
542 |
< |
final int phase; |
543 |
< |
QNode(Thread t, int c) { |
544 |
< |
thread = t; |
545 |
< |
phase = c; |
546 |
< |
} |
547 |
< |
} |
548 |
< |
|
549 |
< |
private void releaseWaiters(int currentPhase) { |
550 |
< |
final AtomicReference<QNode> head = this.head; |
551 |
< |
QNode p; |
552 |
< |
while ((p = head.get()) != null && p.phase != currentPhase) { |
553 |
< |
if (head.compareAndSet(p, null)) { |
554 |
< |
do { |
555 |
< |
Thread t = p.thread; |
556 |
< |
if (t != null) { |
557 |
< |
p.thread = null; |
558 |
< |
LockSupport.unpark(t); |
559 |
< |
} |
560 |
< |
} while ((p = p.next) != null); |
561 |
< |
} |
562 |
< |
} |
563 |
< |
} |
724 |
> |
// methods for waiting |
725 |
|
|
726 |
|
/** The number of CPUs, for spin control */ |
727 |
|
static final int NCPUS = Runtime.getRuntime().availableProcessors(); |
728 |
|
|
729 |
|
/** |
730 |
|
* The number of times to spin before blocking in timed waits. |
731 |
< |
* The value is empirically derived |
731 |
> |
* The value is empirically derived. |
732 |
|
*/ |
733 |
< |
static final int maxTimedSpins = (NCPUS < 2)? 0 : 32; |
733 |
> |
static final int maxTimedSpins = (NCPUS < 2)? 0 : 32; |
734 |
|
|
735 |
|
/** |
736 |
|
* The number of times to spin before blocking in untimed waits. |
746 |
|
static final long spinForTimeoutThreshold = 1000L; |
747 |
|
|
748 |
|
/** |
749 |
+ |
* Wait nodes for Treiber stack representing wait queue for non-FJ |
750 |
+ |
* tasks. |
751 |
+ |
*/ |
752 |
+ |
static final class QNode { |
753 |
+ |
QNode next; |
754 |
+ |
volatile Thread thread; // nulled to cancel wait |
755 |
+ |
QNode() { |
756 |
+ |
thread = Thread.currentThread(); |
757 |
+ |
} |
758 |
+ |
void signal() { |
759 |
+ |
Thread t = thread; |
760 |
+ |
if (t != null) { |
761 |
+ |
thread = null; |
762 |
+ |
LockSupport.unpark(t); |
763 |
+ |
} |
764 |
+ |
} |
765 |
+ |
} |
766 |
+ |
|
767 |
+ |
/** |
768 |
+ |
* Removes and signals waiting threads from wait queue |
769 |
+ |
*/ |
770 |
+ |
private void releaseWaiters(int phase) { |
771 |
+ |
AtomicReference<QNode> head = queueFor(phase); |
772 |
+ |
QNode q; |
773 |
+ |
while ((q = head.get()) != null) { |
774 |
+ |
if (head.compareAndSet(q, q.next)) |
775 |
+ |
q.signal(); |
776 |
+ |
} |
777 |
+ |
} |
778 |
+ |
|
779 |
+ |
/** |
780 |
|
* Enqueues node and waits unless aborted or signalled. |
781 |
|
*/ |
782 |
< |
private boolean untimedWait(Thread thread, int currentPhase, |
783 |
< |
boolean abortOnInterrupt) { |
592 |
< |
final AtomicReference<QNode> head = this.head; |
593 |
< |
final AtomicLong state = this.state; |
594 |
< |
boolean wasInterrupted = false; |
782 |
> |
private int untimedWait(int phase) { |
783 |
> |
int spins = maxUntimedSpins; |
784 |
|
QNode node = null; |
785 |
+ |
boolean interrupted = false; |
786 |
|
boolean queued = false; |
787 |
< |
int spins = maxUntimedSpins; |
788 |
< |
while (phaseOf(state.get()) == currentPhase) { |
789 |
< |
QNode h; |
790 |
< |
if (node != null && queued) { |
791 |
< |
if (node.thread != null) { |
792 |
< |
LockSupport.park(); |
793 |
< |
if (Thread.interrupted()) { |
604 |
< |
wasInterrupted = true; |
605 |
< |
if (abortOnInterrupt) |
606 |
< |
break; |
607 |
< |
} |
787 |
> |
int p; |
788 |
> |
while ((p = getPhase()) == phase) { |
789 |
> |
interrupted = Thread.interrupted(); |
790 |
> |
if (node != null) { |
791 |
> |
if (!queued) { |
792 |
> |
AtomicReference<QNode> head = queueFor(phase); |
793 |
> |
queued = head.compareAndSet(node.next = head.get(), node); |
794 |
|
} |
795 |
+ |
else if (node.thread != null) |
796 |
+ |
LockSupport.park(this); |
797 |
|
} |
798 |
< |
else if ((h = head.get()) != null && h.phase != currentPhase) { |
799 |
< |
if (phaseOf(state.get()) == currentPhase) { // must recheck |
800 |
< |
if (head.compareAndSet(h, h.next)) { |
801 |
< |
Thread t = h.thread; // help clear out old waiters |
802 |
< |
if (t != null) { |
803 |
< |
h.thread = null; |
804 |
< |
LockSupport.unpark(t); |
805 |
< |
} |
806 |
< |
} |
798 |
> |
else if (spins <= 0) |
799 |
> |
node = new QNode(); |
800 |
> |
else |
801 |
> |
--spins; |
802 |
> |
} |
803 |
> |
if (node != null) |
804 |
> |
node.thread = null; |
805 |
> |
if (interrupted) |
806 |
> |
Thread.currentThread().interrupt(); |
807 |
> |
releaseWaiters(phase); |
808 |
> |
return p; |
809 |
> |
} |
810 |
> |
|
811 |
> |
/** |
812 |
> |
* Messier interruptible version |
813 |
> |
*/ |
814 |
> |
private int interruptibleWait(int phase) throws InterruptedException { |
815 |
> |
int spins = maxUntimedSpins; |
816 |
> |
QNode node = null; |
817 |
> |
boolean queued = false; |
818 |
> |
boolean interrupted = false; |
819 |
> |
int p; |
820 |
> |
while ((p = getPhase()) == phase) { |
821 |
> |
if (interrupted = Thread.interrupted()) |
822 |
> |
break; |
823 |
> |
if (node != null) { |
824 |
> |
if (!queued) { |
825 |
> |
AtomicReference<QNode> head = queueFor(phase); |
826 |
> |
queued = head.compareAndSet(node.next = head.get(), node); |
827 |
|
} |
828 |
< |
else |
829 |
< |
break; |
828 |
> |
else if (node.thread != null) |
829 |
> |
LockSupport.park(this); |
830 |
|
} |
623 |
– |
else if (node != null) |
624 |
– |
queued = head.compareAndSet(node.next = h, node); |
831 |
|
else if (spins <= 0) |
832 |
< |
node = new QNode(thread, currentPhase); |
832 |
> |
node = new QNode(); |
833 |
|
else |
834 |
|
--spins; |
835 |
|
} |
836 |
|
if (node != null) |
837 |
|
node.thread = null; |
838 |
< |
return wasInterrupted; |
838 |
> |
if (interrupted) |
839 |
> |
throw new InterruptedException(); |
840 |
> |
releaseWaiters(phase); |
841 |
> |
return p; |
842 |
|
} |
843 |
|
|
844 |
|
/** |
845 |
< |
* Messier timeout version |
845 |
> |
* Even messier timeout version. |
846 |
|
*/ |
847 |
< |
private void timedWait(Thread thread, int currentPhase, long nanos) |
847 |
> |
private int timedWait(int phase, long nanos) |
848 |
|
throws InterruptedException, TimeoutException { |
849 |
< |
final AtomicReference<QNode> head = this.head; |
850 |
< |
final AtomicLong state = this.state; |
851 |
< |
long lastTime = System.nanoTime(); |
852 |
< |
QNode node = null; |
853 |
< |
boolean queued = false; |
854 |
< |
int spins = maxTimedSpins; |
855 |
< |
while (phaseOf(state.get()) == currentPhase) { |
856 |
< |
QNode h; |
857 |
< |
long now = System.nanoTime(); |
649 |
< |
nanos -= now - lastTime; |
650 |
< |
lastTime = now; |
651 |
< |
if (nanos <= 0) { |
652 |
< |
if (node != null) |
653 |
< |
node.thread = null; |
654 |
< |
if (phaseOf(state.get()) == currentPhase) |
655 |
< |
throw new TimeoutException(); |
656 |
< |
else |
849 |
> |
int p; |
850 |
> |
if ((p = getPhase()) == phase) { |
851 |
> |
long lastTime = System.nanoTime(); |
852 |
> |
int spins = maxTimedSpins; |
853 |
> |
QNode node = null; |
854 |
> |
boolean queued = false; |
855 |
> |
boolean interrupted = false; |
856 |
> |
while ((p = getPhase()) == phase) { |
857 |
> |
if (interrupted = Thread.interrupted()) |
858 |
|
break; |
859 |
< |
} |
860 |
< |
else if (node != null && queued) { |
861 |
< |
if (node.thread != null && |
862 |
< |
nanos > spinForTimeoutThreshold) { |
863 |
< |
// LockSupport.parkNanos(this, nanos); |
864 |
< |
LockSupport.parkNanos(nanos); |
865 |
< |
if (Thread.interrupted()) { |
866 |
< |
node.thread = null; |
666 |
< |
throw new InterruptedException(); |
859 |
> |
long now = System.nanoTime(); |
860 |
> |
if ((nanos -= now - lastTime) <= 0) |
861 |
> |
break; |
862 |
> |
lastTime = now; |
863 |
> |
if (node != null) { |
864 |
> |
if (!queued) { |
865 |
> |
AtomicReference<QNode> head = queueFor(phase); |
866 |
> |
queued = head.compareAndSet(node.next = head.get(), node); |
867 |
|
} |
868 |
< |
} |
869 |
< |
} |
870 |
< |
else if ((h = head.get()) != null && h.phase != currentPhase) { |
671 |
< |
if (phaseOf(state.get()) == currentPhase) { // must recheck |
672 |
< |
if (head.compareAndSet(h, h.next)) { |
673 |
< |
Thread t = h.thread; // help clear out old waiters |
674 |
< |
if (t != null) { |
675 |
< |
h.thread = null; |
676 |
< |
LockSupport.unpark(t); |
677 |
< |
} |
868 |
> |
else if (node.thread != null && |
869 |
> |
nanos > spinForTimeoutThreshold) { |
870 |
> |
LockSupport.parkNanos(this, nanos); |
871 |
|
} |
872 |
|
} |
873 |
+ |
else if (spins <= 0) |
874 |
+ |
node = new QNode(); |
875 |
|
else |
876 |
< |
break; |
876 |
> |
--spins; |
877 |
> |
} |
878 |
> |
if (node != null) |
879 |
> |
node.thread = null; |
880 |
> |
if (interrupted) |
881 |
> |
throw new InterruptedException(); |
882 |
> |
if (p == phase && (p = getPhase()) == phase) |
883 |
> |
throw new TimeoutException(); |
884 |
> |
} |
885 |
> |
releaseWaiters(phase); |
886 |
> |
return p; |
887 |
> |
} |
888 |
> |
|
889 |
> |
// Temporary Unsafe mechanics for preliminary release |
890 |
> |
|
891 |
> |
static final Unsafe _unsafe; |
892 |
> |
static final long stateOffset; |
893 |
> |
|
894 |
> |
static { |
895 |
> |
try { |
896 |
> |
if (Phaser.class.getClassLoader() != null) { |
897 |
> |
Field f = Unsafe.class.getDeclaredField("theUnsafe"); |
898 |
> |
f.setAccessible(true); |
899 |
> |
_unsafe = (Unsafe)f.get(null); |
900 |
|
} |
683 |
– |
else if (node != null) |
684 |
– |
queued = head.compareAndSet(node.next = h, node); |
685 |
– |
else if (spins <= 0) |
686 |
– |
node = new QNode(thread, currentPhase); |
901 |
|
else |
902 |
< |
--spins; |
902 |
> |
_unsafe = Unsafe.getUnsafe(); |
903 |
> |
stateOffset = _unsafe.objectFieldOffset |
904 |
> |
(Phaser.class.getDeclaredField("state")); |
905 |
> |
} catch (Exception e) { |
906 |
> |
throw new RuntimeException("Could not initialize intrinsics", e); |
907 |
|
} |
690 |
– |
if (node != null) |
691 |
– |
node.thread = null; |
908 |
|
} |
909 |
|
|
910 |
+ |
final boolean casState(long cmp, long val) { |
911 |
+ |
return _unsafe.compareAndSwapLong(this, stateOffset, cmp, val); |
912 |
+ |
} |
913 |
|
} |
695 |
– |
|