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package jsr166y; |
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import java.util.concurrent.*; |
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import java.util.concurrent.TimeUnit; |
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import java.util.concurrent.TimeoutException; |
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import java.util.concurrent.atomic.AtomicReference; |
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import java.util.concurrent.locks.LockSupport; |
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/** |
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* A reusable synchronization barrier, similar in functionality to a |
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* A reusable synchronization barrier, similar in functionality to |
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* {@link java.util.concurrent.CyclicBarrier CyclicBarrier} and |
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* {@link java.util.concurrent.CountDownLatch CountDownLatch} |
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* but supporting more flexible usage. |
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* |
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* <ul> |
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* |
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* <li> The number of parties synchronizing on a phaser may vary over |
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* time. A task may register to be a party at any time, and may |
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* deregister upon arriving at the barrier. As is the case with most |
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* basic synchronization constructs, registration and deregistration |
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* affect only internal counts; they do not establish any further |
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* internal bookkeeping, so tasks cannot query whether they are |
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* registered. (However, you can introduce such bookkeeping by |
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* subclassing this class.) |
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* |
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* <li> Each generation has an associated phase value, starting at |
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* zero, and advancing when all parties reach the barrier (wrapping |
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* around to zero after reaching {@code Integer.MAX_VALUE}). |
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* |
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* <li> Like a CyclicBarrier, a Phaser may be repeatedly awaited. |
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* Method {@code arriveAndAwaitAdvance} has effect analogous to |
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* {@code CyclicBarrier.await}. However, Phasers separate two |
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* aspects of coordination, that may also be invoked independently: |
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* <p> <b>Registration.</b> Unlike the case for other barriers, the |
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* number of parties <em>registered</em> to synchronize on a phaser |
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* may vary over time. Tasks may be registered at any time (using |
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* methods {@link #register}, {@link #bulkRegister}, or forms of |
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* constructors establishing initial numbers of parties), and |
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* optionally deregistered upon any arrival (using {@link |
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* #arriveAndDeregister}). As is the case with most basic |
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* synchronization constructs, registration and deregistration affect |
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* only internal counts; they do not establish any further internal |
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* bookkeeping, so tasks cannot query whether they are registered. |
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* (However, you can introduce such bookkeeping by subclassing this |
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* class.) |
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* |
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* <p> <b>Synchronization.</b> Like a {@code CyclicBarrier}, a {@code |
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* Phaser} may be repeatedly awaited. Method {@link |
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* #arriveAndAwaitAdvance} has effect analogous to {@link |
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* java.util.concurrent.CyclicBarrier#await CyclicBarrier.await}. Each |
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* generation of a phaser has an associated phase number. The phase |
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* number starts at zero, and advances when all parties arrive at the |
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* phaser, wrapping around to zero after reaching {@code |
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* Integer.MAX_VALUE}. The use of phase numbers enables independent |
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* control of actions upon arrival at a phaser and upon awaiting |
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* others, via two kinds of methods that may be invoked by any |
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* registered party: |
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* |
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* <ul> |
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* |
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* <li> Arriving at a barrier. Methods {@code arrive} and |
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* {@code arriveAndDeregister} do not block, but return |
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* the phase value current upon entry to the method. |
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* |
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* <li> Awaiting others. Method {@code awaitAdvance} requires an |
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* argument indicating the entry phase, and returns when the |
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* barrier advances to a new phase. |
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* </ul> |
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* |
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* |
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* <li> Barrier actions, performed by the task triggering a phase |
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* advance while others may be waiting, are arranged by overriding |
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* method {@code onAdvance}, that also controls termination. |
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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. |
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* |
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* <li> Phasers may enter a <em>termination</em> state in which all |
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* actions immediately return without updating phaser state or waiting |
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* for advance, and indicating (via a negative phase value) that |
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* execution is complete. Termination is triggered by executing the |
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* overridable {@code onAdvance} method that is invoked each time the |
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* barrier is about to be tripped. When a Phaser is controlling an |
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* action with a fixed number of iterations, it is often convenient to |
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* override this method to cause termination when the current phase |
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* number reaches a threshold. Method {@code forceTermination} is also |
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* available to abruptly release waiting threads and allow them to |
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* terminate. |
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* |
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* <li> Phasers may be tiered to reduce contention. Phasers with large |
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* numbers of parties that would otherwise experience heavy |
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* synchronization contention costs may instead be arranged in trees. |
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* This will typically greatly increase throughput even though it |
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* incurs somewhat greater per-operation overhead. |
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* |
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* <li> By default, {@code awaitAdvance} continues to wait even if |
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* the waiting thread is interrupted. And unlike the case in |
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* CyclicBarriers, exceptions encountered while tasks wait |
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* interruptibly or with timeout do not change the state of the |
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* barrier. If necessary, you can perform any associated recovery |
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* within handlers of those exceptions, often after invoking |
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* {@code forceTermination}. |
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* |
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* <li>Phasers ensure lack of starvation when used by ForkJoinTasks. |
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* <li> <b>Arrival.</b> Methods {@link #arrive} and |
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* {@link #arriveAndDeregister} record arrival. These methods |
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* do not block, but return an associated <em>arrival phase |
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* number</em>; that is, the phase number of the phaser to which |
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* the arrival applied. When the final party for a given phase |
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* arrives, an optional action is performed and the phase |
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* advances. These actions are performed by the party |
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* triggering a phase advance, and are arranged by overriding |
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* method {@link #onAdvance(int, int)}, which also controls |
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* termination. Overriding this method is similar to, but more |
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* flexible than, providing a barrier action to a {@code |
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* CyclicBarrier}. |
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* |
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* <li> <b>Waiting.</b> Method {@link #awaitAdvance} requires an |
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* argument indicating an arrival phase number, and returns when |
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* the phaser advances to (or is already at) a different phase. |
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* Unlike similar constructions using {@code CyclicBarrier}, |
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* method {@code awaitAdvance} continues to wait even if the |
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* waiting thread is interrupted. Interruptible and timeout |
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* versions are also available, but exceptions encountered while |
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* tasks wait interruptibly or with timeout do not change the |
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* state of the phaser. If necessary, you can perform any |
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* associated recovery within handlers of those exceptions, |
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* often after invoking {@code forceTermination}. Phasers may |
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* also be used by tasks executing in a {@link ForkJoinPool}, |
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* which will ensure sufficient parallelism to execute tasks |
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* when others are blocked waiting for a phase to advance. |
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* |
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* </ul> |
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* |
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* <p> <b>Termination.</b> A phaser may enter a <em>termination</em> |
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* state, that may be checked using method {@link #isTerminated}. Upon |
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* termination, all synchronization methods immediately return without |
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* waiting for advance, as indicated by a negative return value. |
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* Similarly, attempts to register upon termination have no effect. |
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* Termination is triggered when an invocation of {@code onAdvance} |
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* returns {@code true}. The default implementation returns {@code |
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* true} if a deregistration has caused the number of registered |
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* parties to become zero. As illustrated below, when phasers control |
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* actions with a fixed number of iterations, it is often convenient |
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* to override this method to cause termination when the current phase |
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* number reaches a threshold. Method {@link #forceTermination} is |
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* also available to abruptly release waiting threads and allow them |
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* to terminate. |
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* |
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* <p> <b>Tiering.</b> Phasers may be <em>tiered</em> (i.e., |
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* constructed in tree structures) to reduce contention. Phasers with |
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* large numbers of parties that would otherwise experience heavy |
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* synchronization contention costs may instead be set up so that |
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* groups of sub-phasers share a common parent. This may greatly |
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* increase throughput even though it incurs greater per-operation |
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* overhead. |
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* |
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* <p>In a tree of tiered phasers, registration and deregistration of |
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* child phasers with their parent are managed automatically. |
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* Whenever the number of registered parties of a child phaser becomes |
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* non-zero (as established in the {@link #Phaser(Phaser,int)} |
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* constructor, {@link #register}, or {@link #bulkRegister}), the |
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* child phaser is registered with its parent. Whenever the number of |
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* registered parties becomes zero as the result of an invocation of |
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* {@link #arriveAndDeregister}, the child phaser is deregistered |
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* from its parent. |
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* |
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* <p><b>Monitoring.</b> While synchronization methods may be invoked |
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* only by registered parties, the current state of a phaser may be |
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* monitored by any caller. At any given moment there are {@link |
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* #getRegisteredParties} parties in total, of which {@link |
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* #getArrivedParties} have arrived at the current phase ({@link |
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* #getPhase}). When the remaining ({@link #getUnarrivedParties}) |
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* parties arrive, the phase advances. The values returned by these |
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* methods may reflect transient states and so are not in general |
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* useful for synchronization control. Method {@link #toString} |
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* returns snapshots of these state queries in a form convenient for |
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* informal monitoring. |
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* |
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* <p><b>Sample usages:</b> |
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* |
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* <p>A Phaser may be used instead of a {@code CountDownLatch} to control |
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* a one-shot action serving a variable number of parties. The typical |
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* idiom is for the method setting this up to first register, then |
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* start the actions, then deregister, as in: |
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* <p>A {@code Phaser} may be used instead of a {@code CountDownLatch} |
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* to control a one-shot action serving a variable number of parties. |
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* The typical idiom is for the method setting this up to first |
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* register, then start the actions, then deregister, as in: |
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* |
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* <pre> {@code |
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* void runTasks(List<Runnable> list) { |
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* void runTasks(List<Runnable> tasks) { |
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* final Phaser phaser = new Phaser(1); // "1" to register self |
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* for (Runnable r : list) { |
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* // create and start threads |
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* for (Runnable task : tasks) { |
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* phaser.register(); |
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* new Thread() { |
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* public void run() { |
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* phaser.arriveAndAwaitAdvance(); // await all creation |
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* r.run(); |
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* phaser.arriveAndDeregister(); // signal completion |
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* task.run(); |
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* } |
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* }.start(); |
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* } |
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* |
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* doSomethingOnBehalfOfWorkers(); |
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* phaser.arrive(); // allow threads to start |
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* int p = phaser.arriveAndDeregister(); // deregister self ... |
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* p = phaser.awaitAdvance(p); // ... and await arrival |
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* otherActions(); // do other things while tasks execute |
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* phaser.awaitAdvance(p); // await final completion |
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* // allow threads to start and deregister self |
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* phaser.arriveAndDeregister(); |
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* }}</pre> |
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* |
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* <p>One way to cause a set of threads to repeatedly perform actions |
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* for a given number of iterations is to override {@code onAdvance}: |
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* |
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* <pre> {@code |
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* void startTasks(List<Runnable> list, final int iterations) { |
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* void startTasks(List<Runnable> tasks, final int iterations) { |
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* final Phaser phaser = new Phaser() { |
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* public boolean onAdvance(int phase, int registeredParties) { |
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* protected boolean onAdvance(int phase, int registeredParties) { |
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* return phase >= iterations || registeredParties == 0; |
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* } |
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* }; |
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* phaser.register(); |
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* for (Runnable r : list) { |
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* for (final Runnable task : tasks) { |
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* phaser.register(); |
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* new Thread() { |
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* public void run() { |
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* do { |
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* r.run(); |
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* task.run(); |
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* phaser.arriveAndAwaitAdvance(); |
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* } while(!phaser.isTerminated(); |
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* } while (!phaser.isTerminated()); |
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* } |
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* }.start(); |
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* } |
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* phaser.arriveAndDeregister(); // deregister self, don't wait |
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* }}</pre> |
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* |
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* <p> To create a set of tasks using a tree of Phasers, |
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* you could use code of the following form, assuming a |
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* Task class with a constructor accepting a Phaser that |
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* it registers for upon construction: |
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* If the main task must later await termination, it |
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* may re-register and then execute a similar loop: |
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* <pre> {@code |
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* // ... |
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* phaser.register(); |
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* while (!phaser.isTerminated()) |
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* phaser.arriveAndAwaitAdvance();}</pre> |
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* |
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* <p>Related constructions may be used to await particular phase numbers |
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* in contexts where you are sure that the phase will never wrap around |
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* {@code Integer.MAX_VALUE}. For example: |
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* |
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* <pre> {@code |
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* void awaitPhase(Phaser phaser, int phase) { |
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* int p = phaser.register(); // assumes caller not already registered |
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* while (p < phase) { |
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* if (phaser.isTerminated()) |
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* // ... deal with unexpected termination |
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* else |
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* p = phaser.arriveAndAwaitAdvance(); |
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* } |
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* phaser.arriveAndDeregister(); |
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* }}</pre> |
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* |
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* |
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* <p>To create a set of {@code n} tasks using a tree of phasers, you |
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* could use code of the following form, assuming a Task class with a |
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* constructor accepting a {@code Phaser} that it registers with upon |
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* construction. After invocation of {@code build(new Task[n], 0, n, |
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* new Phaser())}, these tasks could then be started, for example by |
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* submitting to a pool: |
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* |
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* <pre> {@code |
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* void build(Task[] actions, int lo, int hi, Phaser b) { |
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* int step = (hi - lo) / TASKS_PER_PHASER; |
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* if (step > 1) { |
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* int i = lo; |
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* while (i < hi) { |
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* int r = Math.min(i + step, hi); |
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* build(actions, i, r, new Phaser(b)); |
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* i = r; |
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* void build(Task[] tasks, int lo, int hi, Phaser ph) { |
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* if (hi - lo > TASKS_PER_PHASER) { |
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* for (int i = lo; i < hi; i += TASKS_PER_PHASER) { |
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* int j = Math.min(i + TASKS_PER_PHASER, hi); |
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* build(tasks, i, j, new Phaser(ph)); |
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* } |
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* } else { |
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* for (int i = lo; i < hi; ++i) |
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* actions[i] = new Task(b); |
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* // assumes new Task(b) performs b.register() |
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* tasks[i] = new Task(ph); |
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* // assumes new Task(ph) performs ph.register() |
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* } |
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* } |
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* // .. initially called, for n tasks via |
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* build(new Task[n], 0, n, new Phaser());}</pre> |
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* }}</pre> |
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* |
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* The best value of {@code TASKS_PER_PHASER} depends mainly on |
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* expected barrier synchronization rates. A value as low as four may |
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* be appropriate for extremely small per-barrier task bodies (thus |
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* expected synchronization rates. A value as low as four may |
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* be appropriate for extremely small per-phase task bodies (thus |
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* high rates), or up to hundreds for extremely large ones. |
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* |
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* </pre> |
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* |
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* <p><b>Implementation notes</b>: This implementation restricts the |
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* maximum number of parties to 65535. Attempts to register additional |
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* parties result in IllegalStateExceptions. However, you can and |
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* parties result in {@code IllegalStateException}. However, you can and |
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* should create tiered phasers to accommodate arbitrarily large sets |
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* of participants. |
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* |
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*/ |
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|
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/** |
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* Barrier state representation. Conceptually, a barrier contains |
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* four values: |
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* |
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* * parties -- the number of parties to wait (16 bits) |
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* * unarrived -- the number of parties yet to hit barrier (16 bits) |
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* * phase -- the generation of the barrier (31 bits) |
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* * terminated -- set if barrier is terminated (1 bit) |
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* |
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* However, to efficiently maintain atomicity, these values are |
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* packed into a single (atomic) long. Termination uses the sign |
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* bit of 32 bit representation of phase, so phase is set to -1 on |
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* termination. Good performance relies on keeping state decoding |
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* and encoding simple, and keeping race windows short. |
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* Primary state representation, holding four fields: |
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* |
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* Note: there are some cheats in arrive() that rely on unarrived |
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* count being lowest 16 bits. |
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* * unarrived -- the number of parties yet to hit barrier (bits 0-15) |
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* * parties -- the number of parties to wait (bits 16-31) |
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* * phase -- the generation of the barrier (bits 32-62) |
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* * terminated -- set if barrier is terminated (bit 63 / sign) |
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* |
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* Except that a phaser with no registered parties is |
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* distinguished with the otherwise illegal state of having zero |
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* parties and one unarrived parties (encoded as EMPTY below). |
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* |
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* To efficiently maintain atomicity, these values are packed into |
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* a single (atomic) long. Good performance relies on keeping |
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* state decoding and encoding simple, and keeping race windows |
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* short. |
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* |
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* All state updates are performed via CAS except initial |
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* registration of a sub-phaser (i.e., one with a non-null |
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* parent). In this (relatively rare) case, we use built-in |
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* synchronization to lock while first registering with its |
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* parent. |
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* |
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* The phase of a subphaser is allowed to lag that of its |
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* ancestors until it is actually accessed -- see method |
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* reconcileState. |
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*/ |
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private volatile long state; |
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|
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private static final int ushortBits = 16; |
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private static final int ushortMask = 0xffff; |
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private static final int phaseMask = 0x7fffffff; |
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private static final int MAX_PARTIES = 0xffff; |
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private static final int MAX_PHASE = 0x7fffffff; |
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private static final int PARTIES_SHIFT = 16; |
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private static final int PHASE_SHIFT = 32; |
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private static final long PHASE_MASK = -1L << PHASE_SHIFT; |
273 |
> |
private static final int UNARRIVED_MASK = 0xffff; // to mask ints |
274 |
> |
private static final long PARTIES_MASK = 0xffff0000L; // to mask longs |
275 |
> |
private static final long TERMINATION_BIT = 1L << 63; |
276 |
> |
|
277 |
> |
// some special values |
278 |
> |
private static final int ONE_ARRIVAL = 1; |
279 |
> |
private static final int ONE_PARTY = 1 << PARTIES_SHIFT; |
280 |
> |
private static final int EMPTY = 1; |
281 |
> |
|
282 |
> |
// The following unpacking methods are usually manually inlined |
283 |
|
|
284 |
|
private static int unarrivedOf(long s) { |
285 |
< |
return (int) (s & ushortMask); |
285 |
> |
int counts = (int)s; |
286 |
> |
return (counts == EMPTY) ? 0 : counts & UNARRIVED_MASK; |
287 |
|
} |
288 |
|
|
289 |
|
private static int partiesOf(long s) { |
290 |
< |
return ((int) s) >>> 16; |
290 |
> |
return (int)s >>> PARTIES_SHIFT; |
291 |
|
} |
292 |
|
|
293 |
|
private static int phaseOf(long s) { |
294 |
< |
return (int) (s >>> 32); |
294 |
> |
return (int) (s >>> PHASE_SHIFT); |
295 |
|
} |
296 |
|
|
297 |
|
private static int arrivedOf(long s) { |
298 |
< |
return partiesOf(s) - unarrivedOf(s); |
299 |
< |
} |
300 |
< |
|
228 |
< |
private static long stateFor(int phase, int parties, int unarrived) { |
229 |
< |
return ((((long) phase) << 32) | (((long) parties) << 16) | |
230 |
< |
(long) unarrived); |
231 |
< |
} |
232 |
< |
|
233 |
< |
private static long trippedStateFor(int phase, int parties) { |
234 |
< |
long lp = (long) parties; |
235 |
< |
return (((long) phase) << 32) | (lp << 16) | lp; |
236 |
< |
} |
237 |
< |
|
238 |
< |
/** |
239 |
< |
* Returns message string for bad bounds exceptions. |
240 |
< |
*/ |
241 |
< |
private static String badBounds(int parties, int unarrived) { |
242 |
< |
return ("Attempt to set " + unarrived + |
243 |
< |
" unarrived of " + parties + " parties"); |
298 |
> |
int counts = (int)s; |
299 |
> |
return (counts == EMPTY) ? 0 : |
300 |
> |
(counts >>> PARTIES_SHIFT) - (counts & UNARRIVED_MASK); |
301 |
|
} |
302 |
|
|
303 |
|
/** |
306 |
|
private final Phaser parent; |
307 |
|
|
308 |
|
/** |
309 |
< |
* The root of Phaser tree. Equals this if not in a tree. Used to |
253 |
< |
* support faster state push-down. |
309 |
> |
* The root of phaser tree. Equals this if not in a tree. |
310 |
|
*/ |
311 |
|
private final Phaser root; |
312 |
|
|
257 |
– |
// Wait queues |
258 |
– |
|
313 |
|
/** |
314 |
|
* Heads of Treiber stacks for waiting threads. To eliminate |
315 |
< |
* contention while releasing some threads while adding others, we |
315 |
> |
* contention when releasing some threads while adding others, we |
316 |
|
* use two of them, alternating across even and odd phases. |
317 |
+ |
* Subphasers share queues with root to speed up releases. |
318 |
|
*/ |
319 |
< |
private final AtomicReference<QNode> evenQ = new AtomicReference<QNode>(); |
320 |
< |
private final AtomicReference<QNode> oddQ = new AtomicReference<QNode>(); |
319 |
> |
private final AtomicReference<QNode> evenQ; |
320 |
> |
private final AtomicReference<QNode> oddQ; |
321 |
|
|
322 |
|
private AtomicReference<QNode> queueFor(int phase) { |
323 |
|
return ((phase & 1) == 0) ? evenQ : oddQ; |
324 |
|
} |
325 |
|
|
326 |
|
/** |
327 |
< |
* Returns current state, first resolving lagged propagation from |
273 |
< |
* root if necessary. |
327 |
> |
* Returns message string for bounds exceptions on arrival. |
328 |
|
*/ |
329 |
< |
private long getReconciledState() { |
330 |
< |
return (parent == null) ? state : reconcileState(); |
329 |
> |
private String badArrive(long s) { |
330 |
> |
return "Attempted arrival of unregistered party for " + |
331 |
> |
stateToString(s); |
332 |
|
} |
333 |
|
|
334 |
|
/** |
335 |
< |
* Recursively resolves state. |
335 |
> |
* Returns message string for bounds exceptions on registration. |
336 |
|
*/ |
337 |
< |
private long reconcileState() { |
338 |
< |
Phaser p = parent; |
339 |
< |
long s = state; |
340 |
< |
if (p != null) { |
341 |
< |
while (unarrivedOf(s) == 0 && phaseOf(s) != phaseOf(root.state)) { |
342 |
< |
long parentState = p.getReconciledState(); |
343 |
< |
int parentPhase = phaseOf(parentState); |
344 |
< |
int phase = phaseOf(s = state); |
345 |
< |
if (phase != parentPhase) { |
346 |
< |
long next = trippedStateFor(parentPhase, partiesOf(s)); |
347 |
< |
if (casState(s, next)) { |
348 |
< |
releaseWaiters(phase); |
349 |
< |
s = next; |
337 |
> |
private String badRegister(long s) { |
338 |
> |
return "Attempt to register more than " + |
339 |
> |
MAX_PARTIES + " parties for " + stateToString(s); |
340 |
> |
} |
341 |
> |
|
342 |
> |
/** |
343 |
> |
* Main implementation for methods arrive and arriveAndDeregister. |
344 |
> |
* Manually tuned to speed up and minimize race windows for the |
345 |
> |
* common case of just decrementing unarrived field. |
346 |
> |
* |
347 |
> |
* @param deregister false for arrive, true for arriveAndDeregister |
348 |
> |
*/ |
349 |
> |
private int doArrive(boolean deregister) { |
350 |
> |
int adj = deregister ? ONE_ARRIVAL|ONE_PARTY : ONE_ARRIVAL; |
351 |
> |
final Phaser root = this.root; |
352 |
> |
for (;;) { |
353 |
> |
long s = (root == this) ? state : reconcileState(); |
354 |
> |
int phase = (int)(s >>> PHASE_SHIFT); |
355 |
> |
int counts = (int)s; |
356 |
> |
int unarrived = (counts & UNARRIVED_MASK) - 1; |
357 |
> |
if (phase < 0) |
358 |
> |
return phase; |
359 |
> |
else if (counts == EMPTY || unarrived < 0) { |
360 |
> |
if (root == this || reconcileState() == s) |
361 |
> |
throw new IllegalStateException(badArrive(s)); |
362 |
> |
} |
363 |
> |
else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, s-=adj)) { |
364 |
> |
if (unarrived == 0) { |
365 |
> |
long n = s & PARTIES_MASK; // base of next state |
366 |
> |
int nextUnarrived = ((int)n) >>> PARTIES_SHIFT; |
367 |
> |
if (root != this) |
368 |
> |
return parent.doArrive(nextUnarrived == 0); |
369 |
> |
if (onAdvance(phase, nextUnarrived)) |
370 |
> |
n |= TERMINATION_BIT; |
371 |
> |
else if (nextUnarrived == 0) |
372 |
> |
n |= EMPTY; |
373 |
> |
else |
374 |
> |
n |= nextUnarrived; |
375 |
> |
n |= ((long)((phase + 1) & MAX_PHASE)) << PHASE_SHIFT; |
376 |
> |
UNSAFE.compareAndSwapLong(this, stateOffset, s, n); |
377 |
> |
releaseWaiters(phase); |
378 |
> |
} |
379 |
> |
return phase; |
380 |
> |
} |
381 |
> |
} |
382 |
> |
} |
383 |
> |
|
384 |
> |
/** |
385 |
> |
* Implementation of register, bulkRegister |
386 |
> |
* |
387 |
> |
* @param registrations number to add to both parties and |
388 |
> |
* unarrived fields. Must be greater than zero. |
389 |
> |
*/ |
390 |
> |
private int doRegister(int registrations) { |
391 |
> |
// adjustment to state |
392 |
> |
long adj = ((long)registrations << PARTIES_SHIFT) | registrations; |
393 |
> |
Phaser par = parent; |
394 |
> |
int phase; |
395 |
> |
for (;;) { |
396 |
> |
long s = state; |
397 |
> |
int counts = (int)s; |
398 |
> |
int parties = counts >>> PARTIES_SHIFT; |
399 |
> |
int unarrived = counts & UNARRIVED_MASK; |
400 |
> |
if (registrations > MAX_PARTIES - parties) |
401 |
> |
throw new IllegalStateException(badRegister(s)); |
402 |
> |
else if ((phase = (int)(s >>> PHASE_SHIFT)) < 0) |
403 |
> |
break; |
404 |
> |
else if (counts != EMPTY) { // not 1st registration |
405 |
> |
if (par == null || reconcileState() == s) { |
406 |
> |
if (unarrived == 0) // wait out advance |
407 |
> |
root.internalAwaitAdvance(phase, null); |
408 |
> |
else if (UNSAFE.compareAndSwapLong(this, stateOffset, |
409 |
> |
s, s + adj)) |
410 |
> |
break; |
411 |
> |
} |
412 |
> |
} |
413 |
> |
else if (par == null) { // 1st root registration |
414 |
> |
long next = (((long) phase) << PHASE_SHIFT) | adj; |
415 |
> |
if (UNSAFE.compareAndSwapLong(this, stateOffset, s, next)) |
416 |
> |
break; |
417 |
> |
} |
418 |
> |
else { |
419 |
> |
synchronized (this) { // 1st sub registration |
420 |
> |
if (state == s) { // recheck under lock |
421 |
> |
par.doRegister(1); |
422 |
> |
do { // force current phase |
423 |
> |
phase = (int)(root.state >>> PHASE_SHIFT); |
424 |
> |
// assert phase < 0 || (int)state == EMPTY; |
425 |
> |
} while (!UNSAFE.compareAndSwapLong |
426 |
> |
(this, stateOffset, state, |
427 |
> |
(((long) phase) << PHASE_SHIFT) | adj)); |
428 |
> |
break; |
429 |
|
} |
430 |
|
} |
431 |
|
} |
432 |
|
} |
433 |
+ |
return phase; |
434 |
+ |
} |
435 |
+ |
|
436 |
+ |
/** |
437 |
+ |
* Resolves lagged phase propagation from root if necessary. |
438 |
+ |
* Reconciliation normally occurs when root has advanced but |
439 |
+ |
* subphasers have not yet done so, in which case they must finish |
440 |
+ |
* their own advance by setting unarrived to parties (or if |
441 |
+ |
* parties is zero, resetting to unregistered EMPTY state). |
442 |
+ |
* However, this method may also be called when "floating" |
443 |
+ |
* subphasers with possibly some unarrived parties are merely |
444 |
+ |
* catching up to current phase, in which case counts are |
445 |
+ |
* unaffected. |
446 |
+ |
* |
447 |
+ |
* @return reconciled state |
448 |
+ |
*/ |
449 |
+ |
private long reconcileState() { |
450 |
+ |
final Phaser root = this.root; |
451 |
+ |
long s = state; |
452 |
+ |
if (root != this) { |
453 |
+ |
int phase, u, p; |
454 |
+ |
// CAS root phase with current parties; possibly trip unarrived |
455 |
+ |
while ((phase = (int)(root.state >>> PHASE_SHIFT)) != |
456 |
+ |
(int)(s >>> PHASE_SHIFT) && |
457 |
+ |
!UNSAFE.compareAndSwapLong |
458 |
+ |
(this, stateOffset, s, |
459 |
+ |
s = ((((long) phase) << PHASE_SHIFT) | (s & PARTIES_MASK) | |
460 |
+ |
((p = (int)s >>> PARTIES_SHIFT) == 0 ? EMPTY : |
461 |
+ |
(u = (int)s & UNARRIVED_MASK) == 0 ? p : u)))) |
462 |
+ |
s = state; |
463 |
+ |
} |
464 |
|
return s; |
465 |
|
} |
466 |
|
|
467 |
|
/** |
468 |
< |
* Creates a new Phaser without any initially registered parties, |
469 |
< |
* initial phase number 0, and no parent. Any thread using this |
470 |
< |
* Phaser will need to first register for it. |
468 |
> |
* Creates a new phaser with no initially registered parties, no |
469 |
> |
* parent, and initial phase number 0. Any thread using this |
470 |
> |
* phaser will need to first register for it. |
471 |
|
*/ |
472 |
|
public Phaser() { |
473 |
< |
this(null); |
473 |
> |
this(null, 0); |
474 |
|
} |
475 |
|
|
476 |
|
/** |
477 |
< |
* Creates a new Phaser with the given numbers of registered |
478 |
< |
* unarrived parties, initial phase number 0, and no parent. |
477 |
> |
* Creates a new phaser with the given number of registered |
478 |
> |
* unarrived parties, no parent, and initial phase number 0. |
479 |
|
* |
480 |
< |
* @param parties the number of parties required to trip barrier |
480 |
> |
* @param parties the number of parties required to advance to the |
481 |
> |
* next phase |
482 |
|
* @throws IllegalArgumentException if parties less than zero |
483 |
|
* or greater than the maximum number of parties supported |
484 |
|
*/ |
487 |
|
} |
488 |
|
|
489 |
|
/** |
490 |
< |
* Creates a new Phaser with the given parent, without any |
325 |
< |
* initially registered parties. If parent is non-null this phaser |
326 |
< |
* is registered with the parent and its initial phase number is |
327 |
< |
* the same as that of parent phaser. |
490 |
> |
* Equivalent to {@link #Phaser(Phaser, int) Phaser(parent, 0)}. |
491 |
|
* |
492 |
|
* @param parent the parent phaser |
493 |
|
*/ |
494 |
|
public Phaser(Phaser parent) { |
495 |
< |
int phase = 0; |
333 |
< |
this.parent = parent; |
334 |
< |
if (parent != null) { |
335 |
< |
this.root = parent.root; |
336 |
< |
phase = parent.register(); |
337 |
< |
} |
338 |
< |
else |
339 |
< |
this.root = this; |
340 |
< |
this.state = trippedStateFor(phase, 0); |
495 |
> |
this(parent, 0); |
496 |
|
} |
497 |
|
|
498 |
|
/** |
499 |
< |
* Creates a new Phaser with the given parent and numbers of |
500 |
< |
* registered unarrived parties. If parent is non-null, this phaser |
501 |
< |
* is registered with the parent and its initial phase number is |
502 |
< |
* the same as that of parent phaser. |
499 |
> |
* Creates a new phaser with the given parent and number of |
500 |
> |
* registered unarrived parties. When the given parent is non-null |
501 |
> |
* and the given number of parties is greater than zero, this |
502 |
> |
* child phaser is registered with its parent. |
503 |
|
* |
504 |
|
* @param parent the parent phaser |
505 |
< |
* @param parties the number of parties required to trip barrier |
505 |
> |
* @param parties the number of parties required to advance to the |
506 |
> |
* next phase |
507 |
|
* @throws IllegalArgumentException if parties less than zero |
508 |
|
* or greater than the maximum number of parties supported |
509 |
|
*/ |
510 |
|
public Phaser(Phaser parent, int parties) { |
511 |
< |
if (parties < 0 || parties > ushortMask) |
511 |
> |
if (parties >>> PARTIES_SHIFT != 0) |
512 |
|
throw new IllegalArgumentException("Illegal number of parties"); |
513 |
|
int phase = 0; |
514 |
|
this.parent = parent; |
515 |
|
if (parent != null) { |
516 |
< |
this.root = parent.root; |
517 |
< |
phase = parent.register(); |
516 |
> |
final Phaser root = parent.root; |
517 |
> |
this.root = root; |
518 |
> |
this.evenQ = root.evenQ; |
519 |
> |
this.oddQ = root.oddQ; |
520 |
> |
if (parties != 0) |
521 |
> |
phase = parent.doRegister(1); |
522 |
|
} |
523 |
< |
else |
523 |
> |
else { |
524 |
|
this.root = this; |
525 |
< |
this.state = trippedStateFor(phase, parties); |
525 |
> |
this.evenQ = new AtomicReference<QNode>(); |
526 |
> |
this.oddQ = new AtomicReference<QNode>(); |
527 |
> |
} |
528 |
> |
this.state = (parties == 0) ? (long) EMPTY : |
529 |
> |
((((long) phase) << PHASE_SHIFT) | |
530 |
> |
(((long) parties) << PARTIES_SHIFT) | |
531 |
> |
((long) parties)); |
532 |
|
} |
533 |
|
|
534 |
|
/** |
535 |
< |
* Adds a new unarrived party to this phaser. |
536 |
< |
* |
537 |
< |
* @return the current barrier phase number upon registration |
535 |
> |
* Adds a new unarrived party to this phaser. If an ongoing |
536 |
> |
* invocation of {@link #onAdvance} is in progress, this method |
537 |
> |
* may await its completion before returning. If this phaser has |
538 |
> |
* a parent, and this phaser previously had no registered parties, |
539 |
> |
* this child phaser is also registered with its parent. If |
540 |
> |
* this phaser is terminated, the attempt to register has |
541 |
> |
* no effect, and a negative value is returned. |
542 |
> |
* |
543 |
> |
* @return the arrival phase number to which this registration |
544 |
> |
* applied. If this value is negative, then this phaser has |
545 |
> |
* terminated, in which case registration has no effect. |
546 |
|
* @throws IllegalStateException if attempting to register more |
547 |
|
* than the maximum supported number of parties |
548 |
|
*/ |
552 |
|
|
553 |
|
/** |
554 |
|
* Adds the given number of new unarrived parties to this phaser. |
555 |
< |
* |
556 |
< |
* @param parties the number of parties required to trip barrier |
557 |
< |
* @return the current barrier phase number upon registration |
555 |
> |
* If an ongoing invocation of {@link #onAdvance} is in progress, |
556 |
> |
* this method may await its completion before returning. If this |
557 |
> |
* phaser has a parent, and the given number of parties is greater |
558 |
> |
* than zero, and this phaser previously had no registered |
559 |
> |
* parties, this child phaser is also registered with its parent. |
560 |
> |
* If this phaser is terminated, the attempt to register has no |
561 |
> |
* effect, and a negative value is returned. |
562 |
> |
* |
563 |
> |
* @param parties the number of additional parties required to |
564 |
> |
* advance to the next phase |
565 |
> |
* @return the arrival phase number to which this registration |
566 |
> |
* applied. If this value is negative, then this phaser has |
567 |
> |
* terminated, in which case registration has no effect. |
568 |
|
* @throws IllegalStateException if attempting to register more |
569 |
|
* than the maximum supported number of parties |
570 |
+ |
* @throws IllegalArgumentException if {@code parties < 0} |
571 |
|
*/ |
572 |
|
public int bulkRegister(int parties) { |
573 |
|
if (parties < 0) |
578 |
|
} |
579 |
|
|
580 |
|
/** |
581 |
< |
* Shared code for register, bulkRegister |
582 |
< |
*/ |
583 |
< |
private int doRegister(int registrations) { |
584 |
< |
int phase; |
585 |
< |
for (;;) { |
586 |
< |
long s = getReconciledState(); |
402 |
< |
phase = phaseOf(s); |
403 |
< |
int unarrived = unarrivedOf(s) + registrations; |
404 |
< |
int parties = partiesOf(s) + registrations; |
405 |
< |
if (phase < 0) |
406 |
< |
break; |
407 |
< |
if (parties > ushortMask || unarrived > ushortMask) |
408 |
< |
throw new IllegalStateException(badBounds(parties, unarrived)); |
409 |
< |
if (phase == phaseOf(root.state) && |
410 |
< |
casState(s, stateFor(phase, parties, unarrived))) |
411 |
< |
break; |
412 |
< |
} |
413 |
< |
return phase; |
414 |
< |
} |
415 |
< |
|
416 |
< |
/** |
417 |
< |
* Arrives at the barrier, but does not wait for others. (You can |
418 |
< |
* in turn wait for others via {@link #awaitAdvance}). |
581 |
> |
* Arrives at this phaser, without waiting for others to arrive. |
582 |
> |
* |
583 |
> |
* <p>It is a usage error for an unregistered party to invoke this |
584 |
> |
* method. However, this error may result in an {@code |
585 |
> |
* IllegalStateException} only upon some subsequent operation on |
586 |
> |
* this phaser, if ever. |
587 |
|
* |
588 |
< |
* @return the barrier phase number upon entry to this method, or a |
421 |
< |
* negative value if terminated |
588 |
> |
* @return the arrival phase number, or a negative value if terminated |
589 |
|
* @throws IllegalStateException if not terminated and the number |
590 |
|
* of unarrived parties would become negative |
591 |
|
*/ |
592 |
|
public int arrive() { |
593 |
< |
int phase; |
427 |
< |
for (;;) { |
428 |
< |
long s = state; |
429 |
< |
phase = phaseOf(s); |
430 |
< |
if (phase < 0) |
431 |
< |
break; |
432 |
< |
int parties = partiesOf(s); |
433 |
< |
int unarrived = unarrivedOf(s) - 1; |
434 |
< |
if (unarrived > 0) { // Not the last arrival |
435 |
< |
if (casState(s, s - 1)) // s-1 adds one arrival |
436 |
< |
break; |
437 |
< |
} |
438 |
< |
else if (unarrived == 0) { // the last arrival |
439 |
< |
Phaser par = parent; |
440 |
< |
if (par == null) { // directly trip |
441 |
< |
if (casState |
442 |
< |
(s, |
443 |
< |
trippedStateFor(onAdvance(phase, parties) ? -1 : |
444 |
< |
((phase + 1) & phaseMask), parties))) { |
445 |
< |
releaseWaiters(phase); |
446 |
< |
break; |
447 |
< |
} |
448 |
< |
} |
449 |
< |
else { // cascade to parent |
450 |
< |
if (casState(s, s - 1)) { // zeroes unarrived |
451 |
< |
par.arrive(); |
452 |
< |
reconcileState(); |
453 |
< |
break; |
454 |
< |
} |
455 |
< |
} |
456 |
< |
} |
457 |
< |
else if (phase != phaseOf(root.state)) // or if unreconciled |
458 |
< |
reconcileState(); |
459 |
< |
else |
460 |
< |
throw new IllegalStateException(badBounds(parties, unarrived)); |
461 |
< |
} |
462 |
< |
return phase; |
593 |
> |
return doArrive(false); |
594 |
|
} |
595 |
|
|
596 |
|
/** |
597 |
< |
* Arrives at the barrier, and deregisters from it, without |
598 |
< |
* waiting for others. Deregistration reduces number of parties |
599 |
< |
* required to trip the barrier in future phases. If this phaser |
597 |
> |
* Arrives at this phaser and deregisters from it without waiting |
598 |
> |
* for others to arrive. Deregistration reduces the number of |
599 |
> |
* parties required to advance in future phases. If this phaser |
600 |
|
* has a parent, and deregistration causes this phaser to have |
601 |
|
* zero parties, this phaser is also deregistered from its parent. |
602 |
|
* |
603 |
< |
* @return the current barrier phase number upon entry to |
604 |
< |
* this method, or a negative value if terminated |
603 |
> |
* <p>It is a usage error for an unregistered party to invoke this |
604 |
> |
* method. However, this error may result in an {@code |
605 |
> |
* IllegalStateException} only upon some subsequent operation on |
606 |
> |
* this phaser, if ever. |
607 |
> |
* |
608 |
> |
* @return the arrival phase number, or a negative value if terminated |
609 |
|
* @throws IllegalStateException if not terminated and the number |
610 |
|
* of registered or unarrived parties would become negative |
611 |
|
*/ |
612 |
|
public int arriveAndDeregister() { |
613 |
< |
// similar code to arrive, but too different to merge |
479 |
< |
Phaser par = parent; |
480 |
< |
int phase; |
481 |
< |
for (;;) { |
482 |
< |
long s = state; |
483 |
< |
phase = phaseOf(s); |
484 |
< |
if (phase < 0) |
485 |
< |
break; |
486 |
< |
int parties = partiesOf(s) - 1; |
487 |
< |
int unarrived = unarrivedOf(s) - 1; |
488 |
< |
if (parties >= 0) { |
489 |
< |
if (unarrived > 0 || (unarrived == 0 && par != null)) { |
490 |
< |
if (casState |
491 |
< |
(s, |
492 |
< |
stateFor(phase, parties, unarrived))) { |
493 |
< |
if (unarrived == 0) { |
494 |
< |
par.arriveAndDeregister(); |
495 |
< |
reconcileState(); |
496 |
< |
} |
497 |
< |
break; |
498 |
< |
} |
499 |
< |
continue; |
500 |
< |
} |
501 |
< |
if (unarrived == 0) { |
502 |
< |
if (casState |
503 |
< |
(s, |
504 |
< |
trippedStateFor(onAdvance(phase, parties) ? -1 : |
505 |
< |
((phase + 1) & phaseMask), parties))) { |
506 |
< |
releaseWaiters(phase); |
507 |
< |
break; |
508 |
< |
} |
509 |
< |
continue; |
510 |
< |
} |
511 |
< |
if (par != null && phase != phaseOf(root.state)) { |
512 |
< |
reconcileState(); |
513 |
< |
continue; |
514 |
< |
} |
515 |
< |
} |
516 |
< |
throw new IllegalStateException(badBounds(parties, unarrived)); |
517 |
< |
} |
518 |
< |
return phase; |
613 |
> |
return doArrive(true); |
614 |
|
} |
615 |
|
|
616 |
|
/** |
617 |
< |
* Arrives at the barrier and awaits others. Equivalent in effect |
618 |
< |
* to {@code awaitAdvance(arrive())}. If you instead need to |
619 |
< |
* await with interruption of timeout, and/or deregister upon |
620 |
< |
* arrival, you can arrange them using analogous constructions. |
617 |
> |
* Arrives at this phaser and awaits others. Equivalent in effect |
618 |
> |
* to {@code awaitAdvance(arrive())}. If you need to await with |
619 |
> |
* interruption or timeout, you can arrange this with an analogous |
620 |
> |
* construction using one of the other forms of the {@code |
621 |
> |
* awaitAdvance} method. If instead you need to deregister upon |
622 |
> |
* arrival, use {@code awaitAdvance(arriveAndDeregister())}. |
623 |
|
* |
624 |
< |
* @return the phase on entry to this method |
624 |
> |
* <p>It is a usage error for an unregistered party to invoke this |
625 |
> |
* method. However, this error may result in an {@code |
626 |
> |
* IllegalStateException} only upon some subsequent operation on |
627 |
> |
* this phaser, if ever. |
628 |
> |
* |
629 |
> |
* @return the arrival phase number, or the (negative) |
630 |
> |
* {@linkplain #getPhase() current phase} if terminated |
631 |
|
* @throws IllegalStateException if not terminated and the number |
632 |
|
* of unarrived parties would become negative |
633 |
|
*/ |
634 |
|
public int arriveAndAwaitAdvance() { |
635 |
< |
return awaitAdvance(arrive()); |
635 |
> |
// Specialization of doArrive+awaitAdvance eliminating some reads/paths |
636 |
> |
final Phaser root = this.root; |
637 |
> |
for (;;) { |
638 |
> |
long s = (root == this) ? state : reconcileState(); |
639 |
> |
int phase = (int)(s >>> PHASE_SHIFT); |
640 |
> |
int counts = (int)s; |
641 |
> |
int unarrived = (counts & UNARRIVED_MASK) - 1; |
642 |
> |
if (phase < 0) |
643 |
> |
return phase; |
644 |
> |
else if (counts == EMPTY || unarrived < 0) { |
645 |
> |
if (reconcileState() == s) |
646 |
> |
throw new IllegalStateException(badArrive(s)); |
647 |
> |
} |
648 |
> |
else if (UNSAFE.compareAndSwapLong(this, stateOffset, s, |
649 |
> |
s -= ONE_ARRIVAL)) { |
650 |
> |
if (unarrived != 0) |
651 |
> |
return root.internalAwaitAdvance(phase, null); |
652 |
> |
if (root != this) |
653 |
> |
return parent.arriveAndAwaitAdvance(); |
654 |
> |
long n = s & PARTIES_MASK; // base of next state |
655 |
> |
int nextUnarrived = ((int)n) >>> PARTIES_SHIFT; |
656 |
> |
if (onAdvance(phase, nextUnarrived)) |
657 |
> |
n |= TERMINATION_BIT; |
658 |
> |
else if (nextUnarrived == 0) |
659 |
> |
n |= EMPTY; |
660 |
> |
else |
661 |
> |
n |= nextUnarrived; |
662 |
> |
int nextPhase = (phase + 1) & MAX_PHASE; |
663 |
> |
n |= (long)nextPhase << PHASE_SHIFT; |
664 |
> |
if (!UNSAFE.compareAndSwapLong(this, stateOffset, s, n)) |
665 |
> |
return (int)(state >>> PHASE_SHIFT); // terminated |
666 |
> |
releaseWaiters(phase); |
667 |
> |
return nextPhase; |
668 |
> |
} |
669 |
> |
} |
670 |
|
} |
671 |
|
|
672 |
|
/** |
673 |
< |
* Awaits the phase of the barrier to advance from the given |
674 |
< |
* value, or returns immediately if argument is negative or this |
675 |
< |
* barrier is terminated. |
676 |
< |
* |
677 |
< |
* @param phase the phase on entry to this method |
678 |
< |
* @return the phase on exit from this method |
673 |
> |
* Awaits the phase of this phaser to advance from the given phase |
674 |
> |
* value, returning immediately if the current phase is not equal |
675 |
> |
* to the given phase value or this phaser is terminated. |
676 |
> |
* |
677 |
> |
* @param phase an arrival phase number, or negative value if |
678 |
> |
* terminated; this argument is normally the value returned by a |
679 |
> |
* previous call to {@code arrive} or {@code arriveAndDeregister}. |
680 |
> |
* @return the next arrival phase number, or the argument if it is |
681 |
> |
* negative, or the (negative) {@linkplain #getPhase() current phase} |
682 |
> |
* if terminated |
683 |
|
*/ |
684 |
|
public int awaitAdvance(int phase) { |
685 |
+ |
final Phaser root = this.root; |
686 |
+ |
long s = (root == this) ? state : reconcileState(); |
687 |
+ |
int p = (int)(s >>> PHASE_SHIFT); |
688 |
|
if (phase < 0) |
689 |
|
return phase; |
690 |
< |
long s = getReconciledState(); |
691 |
< |
int p = phaseOf(s); |
692 |
< |
if (p != phase) |
549 |
< |
return p; |
550 |
< |
if (unarrivedOf(s) == 0 && parent != null) |
551 |
< |
parent.awaitAdvance(phase); |
552 |
< |
// Fall here even if parent waited, to reconcile and help release |
553 |
< |
return untimedWait(phase); |
690 |
> |
if (p == phase) |
691 |
> |
return root.internalAwaitAdvance(phase, null); |
692 |
> |
return p; |
693 |
|
} |
694 |
|
|
695 |
|
/** |
696 |
< |
* Awaits the phase of the barrier to advance from the given |
697 |
< |
* value, or returns immediately if argument is negative or this |
698 |
< |
* barrier is terminated, or throws InterruptedException if |
699 |
< |
* interrupted while waiting. |
700 |
< |
* |
701 |
< |
* @param phase the phase on entry to this method |
702 |
< |
* @return the phase on exit from this method |
696 |
> |
* Awaits the phase of this phaser to advance from the given phase |
697 |
> |
* value, throwing {@code InterruptedException} if interrupted |
698 |
> |
* while waiting, or returning immediately if the current phase is |
699 |
> |
* not equal to the given phase value or this phaser is |
700 |
> |
* terminated. |
701 |
> |
* |
702 |
> |
* @param phase an arrival phase number, or negative value if |
703 |
> |
* terminated; this argument is normally the value returned by a |
704 |
> |
* previous call to {@code arrive} or {@code arriveAndDeregister}. |
705 |
> |
* @return the next arrival phase number, or the argument if it is |
706 |
> |
* negative, or the (negative) {@linkplain #getPhase() current phase} |
707 |
> |
* if terminated |
708 |
|
* @throws InterruptedException if thread interrupted while waiting |
709 |
|
*/ |
710 |
|
public int awaitAdvanceInterruptibly(int phase) |
711 |
|
throws InterruptedException { |
712 |
+ |
final Phaser root = this.root; |
713 |
+ |
long s = (root == this) ? state : reconcileState(); |
714 |
+ |
int p = (int)(s >>> PHASE_SHIFT); |
715 |
|
if (phase < 0) |
716 |
|
return phase; |
717 |
< |
long s = getReconciledState(); |
718 |
< |
int p = phaseOf(s); |
719 |
< |
if (p != phase) |
720 |
< |
return p; |
721 |
< |
if (unarrivedOf(s) == 0 && parent != null) |
722 |
< |
parent.awaitAdvanceInterruptibly(phase); |
723 |
< |
return interruptibleWait(phase); |
717 |
> |
if (p == phase) { |
718 |
> |
QNode node = new QNode(this, phase, true, false, 0L); |
719 |
> |
p = root.internalAwaitAdvance(phase, node); |
720 |
> |
if (node.wasInterrupted) |
721 |
> |
throw new InterruptedException(); |
722 |
> |
} |
723 |
> |
return p; |
724 |
|
} |
725 |
|
|
726 |
|
/** |
727 |
< |
* Awaits the phase of the barrier to advance from the given value |
728 |
< |
* or the given timeout elapses, or returns immediately if |
729 |
< |
* argument is negative or this barrier is terminated. |
730 |
< |
* |
731 |
< |
* @param phase the phase on entry to this method |
732 |
< |
* @return the phase on exit from this method |
727 |
> |
* Awaits the phase of this phaser to advance from the given phase |
728 |
> |
* value or the given timeout to elapse, throwing {@code |
729 |
> |
* InterruptedException} if interrupted while waiting, or |
730 |
> |
* returning immediately if the current phase is not equal to the |
731 |
> |
* given phase value or this phaser is terminated. |
732 |
> |
* |
733 |
> |
* @param phase an arrival phase number, or negative value if |
734 |
> |
* terminated; this argument is normally the value returned by a |
735 |
> |
* previous call to {@code arrive} or {@code arriveAndDeregister}. |
736 |
> |
* @param timeout how long to wait before giving up, in units of |
737 |
> |
* {@code unit} |
738 |
> |
* @param unit a {@code TimeUnit} determining how to interpret the |
739 |
> |
* {@code timeout} parameter |
740 |
> |
* @return the next arrival phase number, or the argument if it is |
741 |
> |
* negative, or the (negative) {@linkplain #getPhase() current phase} |
742 |
> |
* if terminated |
743 |
|
* @throws InterruptedException if thread interrupted while waiting |
744 |
|
* @throws TimeoutException if timed out while waiting |
745 |
|
*/ |
746 |
|
public int awaitAdvanceInterruptibly(int phase, |
747 |
|
long timeout, TimeUnit unit) |
748 |
|
throws InterruptedException, TimeoutException { |
749 |
+ |
long nanos = unit.toNanos(timeout); |
750 |
+ |
final Phaser root = this.root; |
751 |
+ |
long s = (root == this) ? state : reconcileState(); |
752 |
+ |
int p = (int)(s >>> PHASE_SHIFT); |
753 |
|
if (phase < 0) |
754 |
|
return phase; |
755 |
< |
long s = getReconciledState(); |
756 |
< |
int p = phaseOf(s); |
757 |
< |
if (p != phase) |
758 |
< |
return p; |
759 |
< |
if (unarrivedOf(s) == 0 && parent != null) |
760 |
< |
parent.awaitAdvanceInterruptibly(phase, timeout, unit); |
761 |
< |
return timedWait(phase, unit.toNanos(timeout)); |
755 |
> |
if (p == phase) { |
756 |
> |
QNode node = new QNode(this, phase, true, true, nanos); |
757 |
> |
p = root.internalAwaitAdvance(phase, node); |
758 |
> |
if (node.wasInterrupted) |
759 |
> |
throw new InterruptedException(); |
760 |
> |
else if (p == phase) |
761 |
> |
throw new TimeoutException(); |
762 |
> |
} |
763 |
> |
return p; |
764 |
|
} |
765 |
|
|
766 |
|
/** |
767 |
< |
* Forces this barrier to enter termination state. Counts of |
768 |
< |
* arrived and registered parties are unaffected. If this phaser |
769 |
< |
* has a parent, it too is terminated. This method may be useful |
770 |
< |
* for coordinating recovery after one or more tasks encounter |
767 |
> |
* Forces this phaser to enter termination state. Counts of |
768 |
> |
* registered parties are unaffected. If this phaser is a member |
769 |
> |
* of a tiered set of phasers, then all of the phasers in the set |
770 |
> |
* are terminated. If this phaser is already terminated, this |
771 |
> |
* method has no effect. This method may be useful for |
772 |
> |
* coordinating recovery after one or more tasks encounter |
773 |
|
* unexpected exceptions. |
774 |
|
*/ |
775 |
|
public void forceTermination() { |
776 |
< |
for (;;) { |
777 |
< |
long s = getReconciledState(); |
778 |
< |
int phase = phaseOf(s); |
779 |
< |
int parties = partiesOf(s); |
780 |
< |
int unarrived = unarrivedOf(s); |
781 |
< |
if (phase < 0 || |
782 |
< |
casState(s, stateFor(-1, parties, unarrived))) { |
776 |
> |
// Only need to change root state |
777 |
> |
final Phaser root = this.root; |
778 |
> |
long s; |
779 |
> |
while ((s = root.state) >= 0) { |
780 |
> |
if (UNSAFE.compareAndSwapLong(root, stateOffset, |
781 |
> |
s, s | TERMINATION_BIT)) { |
782 |
> |
// signal all threads |
783 |
|
releaseWaiters(0); |
784 |
|
releaseWaiters(1); |
620 |
– |
if (parent != null) |
621 |
– |
parent.forceTermination(); |
785 |
|
return; |
786 |
|
} |
787 |
|
} |
790 |
|
/** |
791 |
|
* Returns the current phase number. The maximum phase number is |
792 |
|
* {@code Integer.MAX_VALUE}, after which it restarts at |
793 |
< |
* zero. Upon termination, the phase number is negative. |
793 |
> |
* zero. Upon termination, the phase number is negative, |
794 |
> |
* in which case the prevailing phase prior to termination |
795 |
> |
* may be obtained via {@code getPhase() + Integer.MIN_VALUE}. |
796 |
|
* |
797 |
|
* @return the phase number, or a negative value if terminated |
798 |
|
*/ |
799 |
|
public final int getPhase() { |
800 |
< |
return phaseOf(getReconciledState()); |
636 |
< |
} |
637 |
< |
|
638 |
< |
/** |
639 |
< |
* Returns {@code true} if the current phase number equals the given phase. |
640 |
< |
* |
641 |
< |
* @param phase the phase |
642 |
< |
* @return {@code true} if the current phase number equals the given phase |
643 |
< |
*/ |
644 |
< |
public final boolean hasPhase(int phase) { |
645 |
< |
return phaseOf(getReconciledState()) == phase; |
800 |
> |
return (int)(root.state >>> PHASE_SHIFT); |
801 |
|
} |
802 |
|
|
803 |
|
/** |
804 |
< |
* Returns the number of parties registered at this barrier. |
804 |
> |
* Returns the number of parties registered at this phaser. |
805 |
|
* |
806 |
|
* @return the number of parties |
807 |
|
*/ |
810 |
|
} |
811 |
|
|
812 |
|
/** |
813 |
< |
* Returns the number of parties that have arrived at the current |
814 |
< |
* phase of this barrier. |
813 |
> |
* Returns the number of registered parties that have arrived at |
814 |
> |
* the current phase of this phaser. If this phaser has terminated, |
815 |
> |
* the returned value is meaningless and arbitrary. |
816 |
|
* |
817 |
|
* @return the number of arrived parties |
818 |
|
*/ |
819 |
|
public int getArrivedParties() { |
820 |
< |
return arrivedOf(state); |
820 |
> |
return arrivedOf(reconcileState()); |
821 |
|
} |
822 |
|
|
823 |
|
/** |
824 |
|
* Returns the number of registered parties that have not yet |
825 |
< |
* arrived at the current phase of this barrier. |
825 |
> |
* arrived at the current phase of this phaser. If this phaser has |
826 |
> |
* terminated, the returned value is meaningless and arbitrary. |
827 |
|
* |
828 |
|
* @return the number of unarrived parties |
829 |
|
*/ |
830 |
|
public int getUnarrivedParties() { |
831 |
< |
return unarrivedOf(state); |
831 |
> |
return unarrivedOf(reconcileState()); |
832 |
|
} |
833 |
|
|
834 |
|
/** |
835 |
< |
* Returns the parent of this phaser, or null if none. |
835 |
> |
* Returns the parent of this phaser, or {@code null} if none. |
836 |
|
* |
837 |
< |
* @return the parent of this phaser, or null if none |
837 |
> |
* @return the parent of this phaser, or {@code null} if none |
838 |
|
*/ |
839 |
|
public Phaser getParent() { |
840 |
|
return parent; |
851 |
|
} |
852 |
|
|
853 |
|
/** |
854 |
< |
* Returns {@code true} if this barrier has been terminated. |
854 |
> |
* Returns {@code true} if this phaser has been terminated. |
855 |
|
* |
856 |
< |
* @return {@code true} if this barrier has been terminated |
856 |
> |
* @return {@code true} if this phaser has been terminated |
857 |
|
*/ |
858 |
|
public boolean isTerminated() { |
859 |
< |
return getPhase() < 0; |
859 |
> |
return root.state < 0L; |
860 |
|
} |
861 |
|
|
862 |
|
/** |
863 |
< |
* Overridable method to perform an action upon phase advance, and |
864 |
< |
* to control termination. This method is invoked whenever the |
865 |
< |
* barrier is tripped (and thus all other waiting parties are |
866 |
< |
* dormant). If it returns true, then, rather than advance the |
867 |
< |
* phase number, this barrier will be set to a final termination |
868 |
< |
* state, and subsequent calls to {@code isTerminated} will |
869 |
< |
* return true. |
870 |
< |
* |
871 |
< |
* <p> The default version returns true when the number of |
872 |
< |
* registered parties is zero. Normally, overrides that arrange |
873 |
< |
* termination for other reasons should also preserve this |
874 |
< |
* property. |
875 |
< |
* |
876 |
< |
* <p> You may override this method to perform an action with side |
877 |
< |
* effects visible to participating tasks, but it is in general |
878 |
< |
* only sensible to do so in designs where all parties register |
879 |
< |
* before any arrive, and all {@code awaitAdvance} at each phase. |
880 |
< |
* Otherwise, you cannot ensure lack of interference. In |
881 |
< |
* particular, this method may be invoked more than once per |
882 |
< |
* transition if other parties successfully register while the |
883 |
< |
* invocation of this method is in progress, thus postponing the |
884 |
< |
* transition until those parties also arrive, re-triggering this |
885 |
< |
* method. |
863 |
> |
* Overridable method to perform an action upon impending phase |
864 |
> |
* advance, and to control termination. This method is invoked |
865 |
> |
* upon arrival of the party advancing this phaser (when all other |
866 |
> |
* waiting parties are dormant). If this method returns {@code |
867 |
> |
* true}, this phaser will be set to a final termination state |
868 |
> |
* upon advance, and subsequent calls to {@link #isTerminated} |
869 |
> |
* will return true. Any (unchecked) Exception or Error thrown by |
870 |
> |
* an invocation of this method is propagated to the party |
871 |
> |
* attempting to advance this phaser, in which case no advance |
872 |
> |
* occurs. |
873 |
> |
* |
874 |
> |
* <p>The arguments to this method provide the state of the phaser |
875 |
> |
* prevailing for the current transition. The effects of invoking |
876 |
> |
* arrival, registration, and waiting methods on this phaser from |
877 |
> |
* within {@code onAdvance} are unspecified and should not be |
878 |
> |
* relied on. |
879 |
> |
* |
880 |
> |
* <p>If this phaser is a member of a tiered set of phasers, then |
881 |
> |
* {@code onAdvance} is invoked only for its root phaser on each |
882 |
> |
* advance. |
883 |
> |
* |
884 |
> |
* <p>To support the most common use cases, the default |
885 |
> |
* implementation of this method returns {@code true} when the |
886 |
> |
* number of registered parties has become zero as the result of a |
887 |
> |
* party invoking {@code arriveAndDeregister}. You can disable |
888 |
> |
* this behavior, thus enabling continuation upon future |
889 |
> |
* registrations, by overriding this method to always return |
890 |
> |
* {@code false}: |
891 |
> |
* |
892 |
> |
* <pre> {@code |
893 |
> |
* Phaser phaser = new Phaser() { |
894 |
> |
* protected boolean onAdvance(int phase, int parties) { return false; } |
895 |
> |
* }}</pre> |
896 |
|
* |
897 |
< |
* @param phase the phase number on entering the barrier |
897 |
> |
* @param phase the current phase number on entry to this method, |
898 |
> |
* before this phaser is advanced |
899 |
|
* @param registeredParties the current number of registered parties |
900 |
< |
* @return {@code true} if this barrier should terminate |
900 |
> |
* @return {@code true} if this phaser should terminate |
901 |
|
*/ |
902 |
|
protected boolean onAdvance(int phase, int registeredParties) { |
903 |
< |
return registeredParties <= 0; |
903 |
> |
return registeredParties == 0; |
904 |
|
} |
905 |
|
|
906 |
|
/** |
910 |
|
* followed by the number of registered parties, and {@code |
911 |
|
* "arrived = "} followed by the number of arrived parties. |
912 |
|
* |
913 |
< |
* @return a string identifying this barrier, as well as its state |
913 |
> |
* @return a string identifying this phaser, as well as its state |
914 |
|
*/ |
915 |
|
public String toString() { |
916 |
< |
long s = getReconciledState(); |
916 |
> |
return stateToString(reconcileState()); |
917 |
> |
} |
918 |
> |
|
919 |
> |
/** |
920 |
> |
* Implementation of toString and string-based error messages |
921 |
> |
*/ |
922 |
> |
private String stateToString(long s) { |
923 |
|
return super.toString() + |
924 |
|
"[phase = " + phaseOf(s) + |
925 |
|
" parties = " + partiesOf(s) + |
926 |
|
" arrived = " + arrivedOf(s) + "]"; |
927 |
|
} |
928 |
|
|
929 |
< |
// methods for waiting |
929 |
> |
// Waiting mechanics |
930 |
> |
|
931 |
> |
/** |
932 |
> |
* Removes and signals threads from queue for phase. |
933 |
> |
*/ |
934 |
> |
private void releaseWaiters(int phase) { |
935 |
> |
QNode q; // first element of queue |
936 |
> |
Thread t; // its thread |
937 |
> |
AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ; |
938 |
> |
while ((q = head.get()) != null && |
939 |
> |
q.phase != (int)(root.state >>> PHASE_SHIFT)) { |
940 |
> |
if (head.compareAndSet(q, q.next) && |
941 |
> |
(t = q.thread) != null) { |
942 |
> |
q.thread = null; |
943 |
> |
LockSupport.unpark(t); |
944 |
> |
} |
945 |
> |
} |
946 |
> |
} |
947 |
> |
|
948 |
> |
/** |
949 |
> |
* Variant of releaseWaiters that additionally tries to remove any |
950 |
> |
* nodes no longer waiting for advance due to timeout or |
951 |
> |
* interrupt. Currently, nodes are removed only if they are at |
952 |
> |
* head of queue, which suffices to reduce memory footprint in |
953 |
> |
* most usages. |
954 |
> |
* |
955 |
> |
* @return current phase on exit |
956 |
> |
*/ |
957 |
> |
private int abortWait(int phase) { |
958 |
> |
AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ; |
959 |
> |
for (;;) { |
960 |
> |
Thread t; |
961 |
> |
QNode q = head.get(); |
962 |
> |
int p = (int)(root.state >>> PHASE_SHIFT); |
963 |
> |
if (q == null || ((t = q.thread) != null && q.phase == p)) |
964 |
> |
return p; |
965 |
> |
if (head.compareAndSet(q, q.next) && t != null) { |
966 |
> |
q.thread = null; |
967 |
> |
LockSupport.unpark(t); |
968 |
> |
} |
969 |
> |
} |
970 |
> |
} |
971 |
> |
|
972 |
> |
/** The number of CPUs, for spin control */ |
973 |
> |
private static final int NCPU = Runtime.getRuntime().availableProcessors(); |
974 |
> |
|
975 |
> |
/** |
976 |
> |
* The number of times to spin before blocking while waiting for |
977 |
> |
* advance, per arrival while waiting. On multiprocessors, fully |
978 |
> |
* blocking and waking up a large number of threads all at once is |
979 |
> |
* usually a very slow process, so we use rechargeable spins to |
980 |
> |
* avoid it when threads regularly arrive: When a thread in |
981 |
> |
* internalAwaitAdvance notices another arrival before blocking, |
982 |
> |
* and there appear to be enough CPUs available, it spins |
983 |
> |
* SPINS_PER_ARRIVAL more times before blocking. The value trades |
984 |
> |
* off good-citizenship vs big unnecessary slowdowns. |
985 |
> |
*/ |
986 |
> |
static final int SPINS_PER_ARRIVAL = (NCPU < 2) ? 1 : 1 << 8; |
987 |
> |
|
988 |
> |
/** |
989 |
> |
* Possibly blocks and waits for phase to advance unless aborted. |
990 |
> |
* Call only from root node. |
991 |
> |
* |
992 |
> |
* @param phase current phase |
993 |
> |
* @param node if non-null, the wait node to track interrupt and timeout; |
994 |
> |
* if null, denotes noninterruptible wait |
995 |
> |
* @return current phase |
996 |
> |
*/ |
997 |
> |
private int internalAwaitAdvance(int phase, QNode node) { |
998 |
> |
releaseWaiters(phase-1); // ensure old queue clean |
999 |
> |
boolean queued = false; // true when node is enqueued |
1000 |
> |
int lastUnarrived = 0; // to increase spins upon change |
1001 |
> |
int spins = SPINS_PER_ARRIVAL; |
1002 |
> |
long s; |
1003 |
> |
int p; |
1004 |
> |
while ((p = (int)((s = state) >>> PHASE_SHIFT)) == phase) { |
1005 |
> |
if (node == null) { // spinning in noninterruptible mode |
1006 |
> |
int unarrived = (int)s & UNARRIVED_MASK; |
1007 |
> |
if (unarrived != lastUnarrived && |
1008 |
> |
(lastUnarrived = unarrived) < NCPU) |
1009 |
> |
spins += SPINS_PER_ARRIVAL; |
1010 |
> |
boolean interrupted = Thread.interrupted(); |
1011 |
> |
if (interrupted || --spins < 0) { // need node to record intr |
1012 |
> |
node = new QNode(this, phase, false, false, 0L); |
1013 |
> |
node.wasInterrupted = interrupted; |
1014 |
> |
} |
1015 |
> |
} |
1016 |
> |
else if (node.isReleasable()) // done or aborted |
1017 |
> |
break; |
1018 |
> |
else if (!queued) { // push onto queue |
1019 |
> |
AtomicReference<QNode> head = (phase & 1) == 0 ? evenQ : oddQ; |
1020 |
> |
QNode q = node.next = head.get(); |
1021 |
> |
if ((q == null || q.phase == phase) && |
1022 |
> |
(int)(state >>> PHASE_SHIFT) == phase) // avoid stale enq |
1023 |
> |
queued = head.compareAndSet(q, node); |
1024 |
> |
} |
1025 |
> |
else { |
1026 |
> |
try { |
1027 |
> |
ForkJoinPool.managedBlock(node); |
1028 |
> |
} catch (InterruptedException ie) { |
1029 |
> |
node.wasInterrupted = true; |
1030 |
> |
} |
1031 |
> |
} |
1032 |
> |
} |
1033 |
> |
|
1034 |
> |
if (node != null) { |
1035 |
> |
if (node.thread != null) |
1036 |
> |
node.thread = null; // avoid need for unpark() |
1037 |
> |
if (node.wasInterrupted && !node.interruptible) |
1038 |
> |
Thread.currentThread().interrupt(); |
1039 |
> |
if (p == phase && (p = (int)(state >>> PHASE_SHIFT)) == phase) |
1040 |
> |
return abortWait(phase); // possibly clean up on abort |
1041 |
> |
} |
1042 |
> |
releaseWaiters(phase); |
1043 |
> |
return p; |
1044 |
> |
} |
1045 |
|
|
1046 |
|
/** |
1047 |
|
* Wait nodes for Treiber stack representing wait queue |
1049 |
|
static final class QNode implements ForkJoinPool.ManagedBlocker { |
1050 |
|
final Phaser phaser; |
1051 |
|
final int phase; |
763 |
– |
final long startTime; |
764 |
– |
final long nanos; |
765 |
– |
final boolean timed; |
1052 |
|
final boolean interruptible; |
1053 |
< |
volatile boolean wasInterrupted = false; |
1053 |
> |
final boolean timed; |
1054 |
> |
boolean wasInterrupted; |
1055 |
> |
long nanos; |
1056 |
> |
long lastTime; |
1057 |
|
volatile Thread thread; // nulled to cancel wait |
1058 |
|
QNode next; |
1059 |
+ |
|
1060 |
|
QNode(Phaser phaser, int phase, boolean interruptible, |
1061 |
< |
boolean timed, long startTime, long nanos) { |
1061 |
> |
boolean timed, long nanos) { |
1062 |
|
this.phaser = phaser; |
1063 |
|
this.phase = phase; |
774 |
– |
this.timed = timed; |
1064 |
|
this.interruptible = interruptible; |
776 |
– |
this.startTime = startTime; |
1065 |
|
this.nanos = nanos; |
1066 |
+ |
this.timed = timed; |
1067 |
+ |
this.lastTime = timed ? System.nanoTime() : 0L; |
1068 |
|
thread = Thread.currentThread(); |
1069 |
|
} |
1070 |
+ |
|
1071 |
|
public boolean isReleasable() { |
1072 |
< |
return (thread == null || |
1073 |
< |
phaser.getPhase() != phase || |
1074 |
< |
(interruptible && wasInterrupted) || |
1075 |
< |
(timed && (nanos - (System.nanoTime() - startTime)) <= 0)); |
1076 |
< |
} |
786 |
< |
public boolean block() { |
787 |
< |
if (Thread.interrupted()) { |
788 |
< |
wasInterrupted = true; |
789 |
< |
if (interruptible) |
790 |
< |
return true; |
791 |
< |
} |
792 |
< |
if (!timed) |
793 |
< |
LockSupport.park(this); |
794 |
< |
else { |
795 |
< |
long waitTime = nanos - (System.nanoTime() - startTime); |
796 |
< |
if (waitTime <= 0) |
797 |
< |
return true; |
798 |
< |
LockSupport.parkNanos(this, waitTime); |
1072 |
> |
if (thread == null) |
1073 |
> |
return true; |
1074 |
> |
if (phaser.getPhase() != phase) { |
1075 |
> |
thread = null; |
1076 |
> |
return true; |
1077 |
|
} |
1078 |
< |
return isReleasable(); |
1079 |
< |
} |
1080 |
< |
void signal() { |
803 |
< |
Thread t = thread; |
804 |
< |
if (t != null) { |
1078 |
> |
if (Thread.interrupted()) |
1079 |
> |
wasInterrupted = true; |
1080 |
> |
if (wasInterrupted && interruptible) { |
1081 |
|
thread = null; |
1082 |
< |
LockSupport.unpark(t); |
1082 |
> |
return true; |
1083 |
|
} |
1084 |
< |
} |
1085 |
< |
boolean doWait() { |
1086 |
< |
if (thread != null) { |
1087 |
< |
try { |
1088 |
< |
ForkJoinPool.managedBlock(this, false); |
1089 |
< |
} catch (InterruptedException ie) { |
1084 |
> |
if (timed) { |
1085 |
> |
if (nanos > 0L) { |
1086 |
> |
long now = System.nanoTime(); |
1087 |
> |
nanos -= now - lastTime; |
1088 |
> |
lastTime = now; |
1089 |
> |
} |
1090 |
> |
if (nanos <= 0L) { |
1091 |
> |
thread = null; |
1092 |
> |
return true; |
1093 |
|
} |
1094 |
|
} |
1095 |
< |
return wasInterrupted; |
1095 |
> |
return false; |
1096 |
|
} |
1097 |
|
|
1098 |
< |
} |
1099 |
< |
|
1100 |
< |
/** |
1101 |
< |
* Removes and signals waiting threads from wait queue. |
1102 |
< |
*/ |
1103 |
< |
private void releaseWaiters(int phase) { |
1104 |
< |
AtomicReference<QNode> head = queueFor(phase); |
1105 |
< |
QNode q; |
827 |
< |
while ((q = head.get()) != null) { |
828 |
< |
if (head.compareAndSet(q, q.next)) |
829 |
< |
q.signal(); |
1098 |
> |
public boolean block() { |
1099 |
> |
if (isReleasable()) |
1100 |
> |
return true; |
1101 |
> |
else if (!timed) |
1102 |
> |
LockSupport.park(this); |
1103 |
> |
else if (nanos > 0) |
1104 |
> |
LockSupport.parkNanos(this, nanos); |
1105 |
> |
return isReleasable(); |
1106 |
|
} |
1107 |
|
} |
1108 |
|
|
1109 |
< |
/** |
834 |
< |
* Tries to enqueue given node in the appropriate wait queue. |
835 |
< |
* |
836 |
< |
* @return true if successful |
837 |
< |
*/ |
838 |
< |
private boolean tryEnqueue(QNode node) { |
839 |
< |
AtomicReference<QNode> head = queueFor(node.phase); |
840 |
< |
return head.compareAndSet(node.next = head.get(), node); |
841 |
< |
} |
1109 |
> |
// Unsafe mechanics |
1110 |
|
|
1111 |
< |
/** |
1112 |
< |
* Enqueues node and waits unless aborted or signalled. |
1113 |
< |
* |
846 |
< |
* @return current phase |
847 |
< |
*/ |
848 |
< |
private int untimedWait(int phase) { |
849 |
< |
QNode node = null; |
850 |
< |
boolean queued = false; |
851 |
< |
boolean interrupted = false; |
852 |
< |
int p; |
853 |
< |
while ((p = getPhase()) == phase) { |
854 |
< |
if (Thread.interrupted()) |
855 |
< |
interrupted = true; |
856 |
< |
else if (node == null) |
857 |
< |
node = new QNode(this, phase, false, false, 0, 0); |
858 |
< |
else if (!queued) |
859 |
< |
queued = tryEnqueue(node); |
860 |
< |
else |
861 |
< |
interrupted = node.doWait(); |
862 |
< |
} |
863 |
< |
if (node != null) |
864 |
< |
node.thread = null; |
865 |
< |
releaseWaiters(phase); |
866 |
< |
if (interrupted) |
867 |
< |
Thread.currentThread().interrupt(); |
868 |
< |
return p; |
869 |
< |
} |
1111 |
> |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
1112 |
> |
private static final long stateOffset = |
1113 |
> |
objectFieldOffset("state", Phaser.class); |
1114 |
|
|
1115 |
< |
/** |
1116 |
< |
* Interruptible version |
1117 |
< |
* @return current phase |
1118 |
< |
*/ |
1119 |
< |
private int interruptibleWait(int phase) throws InterruptedException { |
1120 |
< |
QNode node = null; |
1121 |
< |
boolean queued = false; |
1122 |
< |
boolean interrupted = false; |
1123 |
< |
int p; |
880 |
< |
while ((p = getPhase()) == phase && !interrupted) { |
881 |
< |
if (Thread.interrupted()) |
882 |
< |
interrupted = true; |
883 |
< |
else if (node == null) |
884 |
< |
node = new QNode(this, phase, true, false, 0, 0); |
885 |
< |
else if (!queued) |
886 |
< |
queued = tryEnqueue(node); |
887 |
< |
else |
888 |
< |
interrupted = node.doWait(); |
889 |
< |
} |
890 |
< |
if (node != null) |
891 |
< |
node.thread = null; |
892 |
< |
if (p != phase || (p = getPhase()) != phase) |
893 |
< |
releaseWaiters(phase); |
894 |
< |
if (interrupted) |
895 |
< |
throw new InterruptedException(); |
896 |
< |
return p; |
1115 |
> |
private static long objectFieldOffset(String field, Class<?> klazz) { |
1116 |
> |
try { |
1117 |
> |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field)); |
1118 |
> |
} catch (NoSuchFieldException e) { |
1119 |
> |
// Convert Exception to corresponding Error |
1120 |
> |
NoSuchFieldError error = new NoSuchFieldError(field); |
1121 |
> |
error.initCause(e); |
1122 |
> |
throw error; |
1123 |
> |
} |
1124 |
|
} |
1125 |
|
|
1126 |
|
/** |
1127 |
< |
* Timeout version. |
1128 |
< |
* @return current phase |
1127 |
> |
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. |
1128 |
> |
* Replace with a simple call to Unsafe.getUnsafe when integrating |
1129 |
> |
* into a jdk. |
1130 |
> |
* |
1131 |
> |
* @return a sun.misc.Unsafe |
1132 |
|
*/ |
903 |
– |
private int timedWait(int phase, long nanos) |
904 |
– |
throws InterruptedException, TimeoutException { |
905 |
– |
long startTime = System.nanoTime(); |
906 |
– |
QNode node = null; |
907 |
– |
boolean queued = false; |
908 |
– |
boolean interrupted = false; |
909 |
– |
int p; |
910 |
– |
while ((p = getPhase()) == phase && !interrupted) { |
911 |
– |
if (Thread.interrupted()) |
912 |
– |
interrupted = true; |
913 |
– |
else if (nanos - (System.nanoTime() - startTime) <= 0) |
914 |
– |
break; |
915 |
– |
else if (node == null) |
916 |
– |
node = new QNode(this, phase, true, true, startTime, nanos); |
917 |
– |
else if (!queued) |
918 |
– |
queued = tryEnqueue(node); |
919 |
– |
else |
920 |
– |
interrupted = node.doWait(); |
921 |
– |
} |
922 |
– |
if (node != null) |
923 |
– |
node.thread = null; |
924 |
– |
if (p != phase || (p = getPhase()) != phase) |
925 |
– |
releaseWaiters(phase); |
926 |
– |
if (interrupted) |
927 |
– |
throw new InterruptedException(); |
928 |
– |
if (p == phase) |
929 |
– |
throw new TimeoutException(); |
930 |
– |
return p; |
931 |
– |
} |
932 |
– |
|
933 |
– |
// Unsafe mechanics for jsr166y 3rd party package. |
1133 |
|
private static sun.misc.Unsafe getUnsafe() { |
1134 |
|
try { |
1135 |
|
return sun.misc.Unsafe.getUnsafe(); |
1136 |
|
} catch (SecurityException se) { |
1137 |
|
try { |
1138 |
|
return java.security.AccessController.doPrivileged |
1139 |
< |
(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1139 |
> |
(new java.security |
1140 |
> |
.PrivilegedExceptionAction<sun.misc.Unsafe>() { |
1141 |
|
public sun.misc.Unsafe run() throws Exception { |
1142 |
< |
return getUnsafeByReflection(); |
1142 |
> |
java.lang.reflect.Field f = sun.misc |
1143 |
> |
.Unsafe.class.getDeclaredField("theUnsafe"); |
1144 |
> |
f.setAccessible(true); |
1145 |
> |
return (sun.misc.Unsafe) f.get(null); |
1146 |
|
}}); |
1147 |
|
} catch (java.security.PrivilegedActionException e) { |
1148 |
|
throw new RuntimeException("Could not initialize intrinsics", |
1150 |
|
} |
1151 |
|
} |
1152 |
|
} |
950 |
– |
|
951 |
– |
private static sun.misc.Unsafe getUnsafeByReflection() |
952 |
– |
throws NoSuchFieldException, IllegalAccessException { |
953 |
– |
java.lang.reflect.Field f = |
954 |
– |
sun.misc.Unsafe.class.getDeclaredField("theUnsafe"); |
955 |
– |
f.setAccessible(true); |
956 |
– |
return (sun.misc.Unsafe) f.get(null); |
957 |
– |
} |
958 |
– |
|
959 |
– |
private static long fieldOffset(String fieldName, Class<?> klazz) { |
960 |
– |
try { |
961 |
– |
return UNSAFE.objectFieldOffset(klazz.getDeclaredField(fieldName)); |
962 |
– |
} catch (NoSuchFieldException e) { |
963 |
– |
// Convert Exception to Error |
964 |
– |
NoSuchFieldError error = new NoSuchFieldError(fieldName); |
965 |
– |
error.initCause(e); |
966 |
– |
throw error; |
967 |
– |
} |
968 |
– |
} |
969 |
– |
|
970 |
– |
private static final sun.misc.Unsafe UNSAFE = getUnsafe(); |
971 |
– |
private static final long stateOffset = |
972 |
– |
fieldOffset("state", Phaser.class); |
973 |
– |
|
974 |
– |
private final boolean casState(long cmp, long val) { |
975 |
– |
return UNSAFE.compareAndSwapLong(this, stateOffset, cmp, val); |
976 |
– |
} |
1153 |
|
} |