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1.1 |
/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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package java.util.concurrent; |
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jsr166 |
1.10 |
import java.util.ArrayList; |
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import java.util.List; |
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1.1 |
import java.util.concurrent.locks.LockSupport; |
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import java.util.function.BiPredicate; |
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import java.util.function.Function; |
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1.15 |
import java.util.function.Supplier; |
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1.1 |
|
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/** |
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1.21 |
* A {@link Flow.Publisher} that asynchronously issues submitted |
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* (non-null) items to current subscribers until it is closed. Each |
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* current subscriber receives newly submitted items in the same order |
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* unless drops or exceptions are encountered. Using a |
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* SubmissionPublisher allows item generators to act as Publishers |
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* relying on drop handling and/or blocking for flow control. |
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1.1 |
* |
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1.16 |
* <p>A SubmissionPublisher uses the {@link Executor} supplied in its |
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1.1 |
* constructor for delivery to subscribers. The best choice of |
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* Executor depends on expected usage. If the generator(s) of |
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* submitted items run in separate threads, and the number of |
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* subscribers can be estimated, consider using a {@link |
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1.25 |
* Executors#newFixedThreadPool}. Otherwise consider using |
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* the default {@link ForkJoinPool#commonPool}. |
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1.1 |
* |
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* <p>Buffering allows producers and consumers to transiently operate |
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* at different rates. Each subscriber uses an independent buffer. |
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1.21 |
* Buffers are created upon first use and expanded as needed up to the |
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1.27 |
* given maximum. (The enforced capacity may be rounded up to the |
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1.21 |
* nearest power of two and/or bounded by the largest value supported |
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* by this implementation.) Invocations of {@link |
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1.16 |
* Flow.Subscription#request} do not directly result in buffer |
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1.24 |
* expansion, but risk saturation if unfilled requests exceed the |
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1.25 |
* maximum capacity. The default value of {@link |
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* Flow#defaultBufferSize} may provide a useful starting point for |
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* choosing a capacity based on expected rates, resources, and usages. |
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1.18 |
* |
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1.1 |
* <p>Publication methods support different policies about what to do |
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* when buffers are saturated. Method {@link #submit} blocks until |
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jsr166 |
1.26 |
* resources are available. This is simplest, but least responsive. |
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* The {@code offer} methods may drop items (either immediately or |
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* with bounded timeout), but provide an opportunity to interpose a |
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* handler and then retry. |
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1.1 |
* |
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* <p>If any Subscriber method throws an exception, its subscription |
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1.27 |
* is cancelled. If the supplied Executor throws {@link |
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* RejectedExecutionException} (or any other RuntimeException or |
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* Error) when attempting to execute a task, or a drop handler throws |
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* an exception when processing a dropped item, then the exception is |
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1.1 |
* rethrown. In these cases, some but not all subscribers may have |
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1.27 |
* received the published item. It is usually good practice to {@link |
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jsr166 |
1.11 |
* #closeExceptionally closeExceptionally} in these cases. |
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1.1 |
* |
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1.15 |
* <p>This class may also serve as a convenient base for subclasses |
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* that generate items, and use the methods in this class to publish |
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* them. For example here is a class that periodically publishes the |
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* items generated from a supplier. (In practice you might add methods |
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* to independently start and stop generation, to share schedulers |
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1.16 |
* among publishers, and so on, or instead use a SubmissionPublisher |
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* as a component rather than a superclass.) |
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1.15 |
* |
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* <pre> {@code |
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* class PeriodicPublisher<T> extends SubmissionPublisher<T> { |
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* final ScheduledFuture<?> periodicTask; |
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* final ScheduledExecutorService scheduler; |
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1.21 |
* PeriodicPublisher(Executor executor, int maxBufferCapacity, |
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* Supplier<? extends T> supplier, |
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1.15 |
* long period, TimeUnit unit) { |
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1.21 |
* super(executor, maxBufferCapacity); |
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1.15 |
* scheduler = new ScheduledThreadPoolExecutor(1); |
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* periodicTask = scheduler.scheduleAtFixedRate( |
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* () -> submit(supplier.get()), 0, period, unit); |
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* } |
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* public void close() { |
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* periodicTask.cancel(false); |
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* scheduler.shutdown(); |
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* super.close(); |
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* } |
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* }}</pre> |
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* |
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1.21 |
* <p>Here is an example of a {@link Flow.Processor} implementation. |
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* It uses single-step requests to its publisher for simplicity of |
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* illustration. A more adaptive version could monitor flow using the |
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1.27 |
* lag estimate returned from {@code submit}, along with other utility |
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1.21 |
* methods. |
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1.16 |
* |
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* <pre> {@code |
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* class TransformProcessor<S,T> extends SubmissionPublisher<T> |
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* implements Flow.Processor<S,T> { |
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* final Function<? super S, ? extends T> function; |
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* Flow.Subscription subscription; |
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1.21 |
* TransformProcessor(Executor executor, int maxBufferCapacity, |
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1.16 |
* Function<? super S, ? extends T> function) { |
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1.21 |
* super(executor, maxBufferCapacity); |
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1.16 |
* this.function = function; |
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* } |
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* public void onSubscribe(Flow.Subscription subscription) { |
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* (this.subscription = subscription).request(1); |
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* } |
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* public void onNext(S item) { |
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* subscription.request(1); |
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* submit(function.apply(item)); |
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* } |
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* public void onError(Throwable ex) { closeExceptionally(ex); } |
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* public void onComplete() { close(); } |
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* }}</pre> |
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* |
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1.1 |
* @param <T> the published item type |
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* @author Doug Lea |
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* @since 1.9 |
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*/ |
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public class SubmissionPublisher<T> implements Flow.Publisher<T>, |
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AutoCloseable { |
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/* |
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* Most mechanics are handled by BufferedSubscription. This class |
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1.17 |
* mainly tracks subscribers and ensures sequentiality, by using |
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* built-in synchronization locks across public methods. (Using |
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* built-in locks works well in the most typical case in which |
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* only one thread submits items). |
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1.1 |
*/ |
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1.25 |
/** The largest possible power of two array size. */ |
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static final int BUFFER_CAPACITY_LIMIT = 1 << 30; |
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1.1 |
|
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1.25 |
/** Round capacity to power of 2, at least 2, at most limit. */ |
132 |
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1.1 |
static final int roundCapacity(int cap) { // to nearest power of 2 |
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int n = cap - 1; |
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n |= n >>> 1; |
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n |= n >>> 2; |
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n |= n >>> 4; |
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n |= n >>> 8; |
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n |= n >>> 16; |
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dl |
1.21 |
return (n <= 0) ? 2 : // at least 2 |
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dl |
1.25 |
(n >= BUFFER_CAPACITY_LIMIT) ? BUFFER_CAPACITY_LIMIT : n + 1; |
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1.1 |
} |
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/** |
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* Clients (BufferedSubscriptions) are maintained in a linked list |
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* (via their "next" fields). This works well for publish loops. |
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* It requires O(n) traversal to check for duplicate subscribers, |
147 |
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* but we expect that subscribing is much less common than |
148 |
dl |
1.13 |
* publishing. Unsubscribing occurs only during traversal loops, |
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1.25 |
* when BufferedSubscription methods return negative values |
150 |
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1.29 |
* signifying that they have been disabled. To reduce |
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* head-of-line blocking, submit and offer methods first call |
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* BufferedSubscription.offer on each subscriber, and place |
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* saturated ones in retries list (using nextRetry field), and |
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* retry, possibly blocking or dropping. |
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dl |
1.1 |
*/ |
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BufferedSubscription<T> clients; |
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dl |
1.20 |
/** Run status, updated only within locks */ |
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volatile boolean closed; |
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dl |
1.1 |
// Parameters for constructing BufferedSubscriptions |
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final Executor executor; |
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final int maxBufferCapacity; |
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1.20 |
/** |
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dl |
1.1 |
* Creates a new SubmissionPublisher using the given Executor for |
167 |
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1.21 |
* async delivery to subscribers, and with the given maximum |
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dl |
1.25 |
* buffer size for each subscriber. |
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1.1 |
* |
170 |
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* @param executor the executor to use for async delivery, |
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* supporting creation of at least one independent thread |
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* @param maxBufferCapacity the maximum capacity for each |
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dl |
1.21 |
* subscriber's buffer (the enforced capacity may be rounded up to |
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* the nearest power of two and/or bounded by the largest value |
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* supported by this implementation; method {@link #getMaxBufferCapacity} |
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* returns the actual value) |
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dl |
1.1 |
* @throws NullPointerException if executor is null |
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dl |
1.21 |
* @throws IllegalArgumentException if maxBufferCapacity not |
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* positive |
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dl |
1.1 |
*/ |
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dl |
1.21 |
public SubmissionPublisher(Executor executor, int maxBufferCapacity) { |
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if (executor == null) |
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throw new NullPointerException(); |
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if (maxBufferCapacity <= 0) |
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throw new IllegalArgumentException("capacity must be positive"); |
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dl |
1.18 |
this.executor = executor; |
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dl |
1.21 |
this.maxBufferCapacity = roundCapacity(maxBufferCapacity); |
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dl |
1.18 |
} |
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dl |
1.1 |
/** |
191 |
dl |
1.25 |
* Creates a new SubmissionPublisher using the {@link |
192 |
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* ForkJoinPool#commonPool()} for async delivery to subscribers, |
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dl |
1.27 |
* and with maximum buffer capacity of {@link |
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* Flow#defaultBufferSize}. |
195 |
dl |
1.25 |
*/ |
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public SubmissionPublisher() { |
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this(ForkJoinPool.commonPool(), Flow.defaultBufferSize()); |
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} |
199 |
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200 |
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/** |
201 |
dl |
1.18 |
* Adds the given Subscriber unless already subscribed. If |
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* already subscribed, the Subscriber's onError method is invoked |
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dl |
1.29 |
* on the existing subscription with an IllegalStateException. |
204 |
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* Otherwise, upon success, the Subscriber's onSubscribe method is |
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* invoked asynchronously with a new Subscription. If onSubscribe |
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* throws an exception, the subscription is cancelled. Otherwise, |
207 |
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* if this SubmissionPublisher is closed, the subscriber's |
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* onComplete method is then invoked. Subscribers may enable |
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* receiving items by invoking the {@code request} method of the |
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* new Subscription, and may unsubscribe by invoking its cancel |
211 |
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* method. |
212 |
dl |
1.18 |
* |
213 |
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* @param subscriber the subscriber |
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* @throws NullPointerException if subscriber is null |
215 |
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*/ |
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public void subscribe(Flow.Subscriber<? super T> subscriber) { |
217 |
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if (subscriber == null) throw new NullPointerException(); |
218 |
dl |
1.20 |
BufferedSubscription<T> subscription = |
219 |
dl |
1.21 |
new BufferedSubscription<T>(subscriber, executor, maxBufferCapacity); |
220 |
dl |
1.19 |
synchronized (this) { |
221 |
dl |
1.29 |
for (BufferedSubscription<T> b = clients, pred = null;;) { |
222 |
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if (b == null) { |
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subscription.onSubscribe(); |
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if (closed) |
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subscription.onComplete(); |
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else if (pred == null) |
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clients = subscription; |
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dl |
1.27 |
else |
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dl |
1.29 |
pred.next = subscription; |
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break; |
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dl |
1.27 |
} |
232 |
dl |
1.29 |
BufferedSubscription<T> next = b.next; |
233 |
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if (b.isDisabled()) { // remove |
234 |
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b.next = null; // detach |
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dl |
1.19 |
if (pred == null) |
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dl |
1.29 |
clients = next; |
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dl |
1.19 |
else |
238 |
dl |
1.29 |
pred.next = next; |
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} |
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else if (subscriber.equals(b.subscriber)) { |
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b.onError(new IllegalStateException("Duplicate subscribe")); |
242 |
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break; |
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dl |
1.19 |
} |
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dl |
1.29 |
else |
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pred = b; |
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b = next; |
247 |
dl |
1.19 |
} |
248 |
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} |
249 |
dl |
1.18 |
} |
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/** |
252 |
dl |
1.16 |
* Publishes the given item to each current subscriber by |
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* asynchronously invoking its onNext method, blocking |
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* uninterruptibly while resources for any subscriber are |
255 |
dl |
1.21 |
* unavailable. This method returns an estimate of the maximum lag |
256 |
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* (number of items submitted but not yet consumed) among all |
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* current subscribers. This value is at least one (accounting for |
258 |
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* this submitted item) if there are any subscribers, else zero. |
259 |
dl |
1.16 |
* |
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* <p>If the Executor for this publisher throws a |
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* RejectedExecutionException (or any other RuntimeException or |
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* Error) when attempting to asynchronously notify subscribers, |
263 |
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* then this exception is rethrown. |
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* |
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* @param item the (non-null) item to publish |
266 |
dl |
1.21 |
* @return the estimated maximum lag among subscribers |
267 |
dl |
1.16 |
* @throws IllegalStateException if closed |
268 |
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* @throws NullPointerException if item is null |
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* @throws RejectedExecutionException if thrown by Executor |
270 |
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*/ |
271 |
dl |
1.21 |
public int submit(T item) { |
272 |
dl |
1.16 |
if (item == null) throw new NullPointerException(); |
273 |
dl |
1.21 |
int lag = 0; |
274 |
dl |
1.27 |
boolean complete; |
275 |
dl |
1.16 |
synchronized (this) { |
276 |
dl |
1.27 |
complete = closed; |
277 |
dl |
1.29 |
BufferedSubscription<T> b = clients; |
278 |
dl |
1.27 |
if (!complete) { |
279 |
dl |
1.29 |
BufferedSubscription<T> pred = null, r = null, rtail = null; |
280 |
dl |
1.27 |
while (b != null) { |
281 |
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BufferedSubscription<T> next = b.next; |
282 |
dl |
1.29 |
int stat = b.offer(item); |
283 |
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if (stat < 0) { // disabled |
284 |
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b.next = null; |
285 |
dl |
1.27 |
if (pred == null) |
286 |
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clients = next; |
287 |
dl |
1.24 |
else |
288 |
dl |
1.27 |
pred.next = next; |
289 |
dl |
1.24 |
} |
290 |
dl |
1.27 |
else { |
291 |
dl |
1.29 |
if (stat > lag) |
292 |
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lag = stat; |
293 |
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else if (stat == 0) { // place on retry list |
294 |
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b.nextRetry = null; |
295 |
dl |
1.27 |
if (rtail == null) |
296 |
dl |
1.29 |
r = b; |
297 |
dl |
1.27 |
else |
298 |
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rtail.nextRetry = b; |
299 |
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rtail = b; |
300 |
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} |
301 |
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pred = b; |
302 |
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} |
303 |
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b = next; |
304 |
dl |
1.21 |
} |
305 |
dl |
1.29 |
while (r != null) { |
306 |
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BufferedSubscription<T> nextRetry = r.nextRetry; |
307 |
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r.nextRetry = null; |
308 |
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int stat = r.submit(item); |
309 |
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if (stat > lag) |
310 |
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lag = stat; |
311 |
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else if (stat < 0 && clients == r) |
312 |
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clients = r.next; // postpone internal unsubscribes |
313 |
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r = nextRetry; |
314 |
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} |
315 |
dl |
1.16 |
} |
316 |
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} |
317 |
dl |
1.27 |
if (complete) |
318 |
|
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throw new IllegalStateException("Closed"); |
319 |
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else |
320 |
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return lag; |
321 |
dl |
1.16 |
} |
322 |
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|
323 |
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/** |
324 |
dl |
1.1 |
* Publishes the given item, if possible, to each current |
325 |
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* subscriber by asynchronously invoking its onNext method. The |
326 |
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* item may be dropped by one or more subscribers if resource |
327 |
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* limits are exceeded, in which case the given handler (if |
328 |
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* non-null) is invoked, and if it returns true, retried once. |
329 |
dl |
1.16 |
* Other calls to methods in this class by other threads are |
330 |
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* blocked while the handler is invoked. Unless recovery is |
331 |
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* assured, options are usually limited to logging the error |
332 |
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* and/or issuing an onError signal to the subscriber. |
333 |
dl |
1.1 |
* |
334 |
dl |
1.21 |
* <p>This method returns a status indicator: If negative, it |
335 |
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* represents the (negative) number of drops (failed attempts to |
336 |
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* issue the item to a subscriber). Otherwise it is an estimate of |
337 |
|
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* the maximum lag (number of items submitted but not yet |
338 |
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* consumed) among all current subscribers. This value is at least |
339 |
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* one (accounting for this submitted item) if there are any |
340 |
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* subscribers, else zero. |
341 |
jsr166 |
1.23 |
* |
342 |
dl |
1.1 |
* <p>If the Executor for this publisher throws a |
343 |
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* RejectedExecutionException (or any other RuntimeException or |
344 |
|
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* Error) when attempting to asynchronously notify subscribers, or |
345 |
|
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* the drop handler throws an exception when processing a dropped |
346 |
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* item, then this exception is rethrown. |
347 |
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* |
348 |
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* @param item the (non-null) item to publish |
349 |
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* @param onDrop if non-null, the handler invoked upon a drop to a |
350 |
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* subscriber, with arguments of the subscriber and item; if it |
351 |
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* returns true, an offer is re-attempted (once) |
352 |
dl |
1.21 |
* @return if negative, the (negative) number of drops; otherwise |
353 |
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* an estimate of maximum lag |
354 |
dl |
1.1 |
* @throws IllegalStateException if closed |
355 |
|
|
* @throws NullPointerException if item is null |
356 |
|
|
* @throws RejectedExecutionException if thrown by Executor |
357 |
|
|
*/ |
358 |
|
|
public int offer(T item, |
359 |
|
|
BiPredicate<Flow.Subscriber<? super T>, ? super T> onDrop) { |
360 |
dl |
1.29 |
return doOffer(0L, item, onDrop); |
361 |
dl |
1.1 |
} |
362 |
|
|
|
363 |
|
|
/** |
364 |
|
|
* Publishes the given item, if possible, to each current |
365 |
|
|
* subscriber by asynchronously invoking its onNext method, |
366 |
|
|
* blocking while resources for any subscription are unavailable, |
367 |
|
|
* up to the specified timeout or the caller thread is |
368 |
dl |
1.16 |
* interrupted, at which point the given handler (if non-null) is |
369 |
|
|
* invoked, and if it returns true, retried once. (The drop |
370 |
|
|
* handler may distinguish timeouts from interrupts by checking |
371 |
|
|
* whether the current thread is interrupted.) Other calls to |
372 |
|
|
* methods in this class by other threads are blocked while the |
373 |
|
|
* handler is invoked. Unless recovery is assured, options are |
374 |
|
|
* usually limited to logging the error and/or issuing an onError |
375 |
|
|
* signal to the subscriber. |
376 |
dl |
1.1 |
* |
377 |
dl |
1.21 |
* <p>This method returns a status indicator: If negative, it |
378 |
|
|
* represents the (negative) number of drops (failed attempts to |
379 |
|
|
* issue the item to a subscriber). Otherwise it is an estimate of |
380 |
|
|
* the maximum lag (number of items submitted but not yet |
381 |
|
|
* consumed) among all current subscribers. This value is at least |
382 |
|
|
* one (accounting for this submitted item) if there are any |
383 |
|
|
* subscribers, else zero. |
384 |
|
|
* |
385 |
dl |
1.1 |
* <p>If the Executor for this publisher throws a |
386 |
|
|
* RejectedExecutionException (or any other RuntimeException or |
387 |
|
|
* Error) when attempting to asynchronously notify subscribers, or |
388 |
|
|
* the drop handler throws an exception when processing a dropped |
389 |
|
|
* item, then this exception is rethrown. |
390 |
|
|
* |
391 |
|
|
* @param item the (non-null) item to publish |
392 |
|
|
* @param timeout how long to wait for resources for any subscriber |
393 |
|
|
* before giving up, in units of {@code unit} |
394 |
|
|
* @param unit a {@code TimeUnit} determining how to interpret the |
395 |
|
|
* {@code timeout} parameter |
396 |
|
|
* @param onDrop if non-null, the handler invoked upon a drop to a |
397 |
|
|
* subscriber, with arguments of the subscriber and item; if it |
398 |
|
|
* returns true, an offer is re-attempted (once) |
399 |
dl |
1.21 |
* @return if negative, the (negative) number of drops; otherwise |
400 |
|
|
* an estimate of maximum lag |
401 |
dl |
1.1 |
* @throws IllegalStateException if closed |
402 |
|
|
* @throws NullPointerException if item is null |
403 |
|
|
* @throws RejectedExecutionException if thrown by Executor |
404 |
|
|
*/ |
405 |
|
|
public int offer(T item, long timeout, TimeUnit unit, |
406 |
|
|
BiPredicate<Flow.Subscriber<? super T>, ? super T> onDrop) { |
407 |
dl |
1.29 |
return doOffer(unit.toNanos(timeout), item, onDrop); |
408 |
|
|
} |
409 |
|
|
|
410 |
|
|
/** Common implementation for both forms of offer */ |
411 |
|
|
final int doOffer(long nanos, T item, |
412 |
|
|
BiPredicate<Flow.Subscriber<? super T>, ? super T> onDrop) { |
413 |
dl |
1.1 |
if (item == null) throw new NullPointerException(); |
414 |
dl |
1.27 |
int lag = 0, drops = 0; |
415 |
|
|
boolean complete; |
416 |
jsr166 |
1.2 |
synchronized (this) { |
417 |
dl |
1.27 |
complete = closed; |
418 |
dl |
1.29 |
BufferedSubscription<T> b = clients; |
419 |
dl |
1.27 |
if (!complete) { |
420 |
dl |
1.29 |
BufferedSubscription<T> pred = null, r = null, rtail = null; |
421 |
dl |
1.27 |
while (b != null) { |
422 |
|
|
BufferedSubscription<T> next = b.next; |
423 |
dl |
1.29 |
int stat = b.offer(item); |
424 |
|
|
if (stat < 0) { |
425 |
|
|
b.next = null; |
426 |
dl |
1.27 |
if (pred == null) |
427 |
|
|
clients = next; |
428 |
|
|
else |
429 |
|
|
pred.next = next; |
430 |
|
|
} |
431 |
|
|
else { |
432 |
dl |
1.29 |
if (stat > lag) |
433 |
|
|
lag = stat; |
434 |
|
|
else if (stat == 0) { |
435 |
|
|
b.nextRetry = null; |
436 |
dl |
1.27 |
if (rtail == null) |
437 |
dl |
1.29 |
r = b; |
438 |
dl |
1.27 |
else |
439 |
|
|
rtail.nextRetry = b; |
440 |
|
|
rtail = b; |
441 |
|
|
} |
442 |
dl |
1.29 |
else if (stat > lag) |
443 |
dl |
1.27 |
lag = stat; |
444 |
|
|
pred = b; |
445 |
|
|
} |
446 |
|
|
b = next; |
447 |
dl |
1.1 |
} |
448 |
dl |
1.29 |
while (r != null) { |
449 |
|
|
BufferedSubscription<T> nextRetry = r.nextRetry; |
450 |
|
|
r.nextRetry = null; |
451 |
|
|
int stat = (nanos > 0L) ? r.timedOffer(item, nanos) : |
452 |
|
|
r.offer(item); |
453 |
|
|
if (stat == 0 && onDrop != null && |
454 |
|
|
onDrop.test(r.subscriber, item)) |
455 |
|
|
stat = r.offer(item); |
456 |
|
|
if (stat == 0) |
457 |
|
|
++drops; |
458 |
|
|
else if (stat > lag) |
459 |
|
|
lag = stat; |
460 |
|
|
else if (stat < 0 && clients == r) |
461 |
|
|
clients = r.next; |
462 |
|
|
r = nextRetry; |
463 |
|
|
} |
464 |
dl |
1.1 |
} |
465 |
|
|
} |
466 |
dl |
1.27 |
if (complete) |
467 |
|
|
throw new IllegalStateException("Closed"); |
468 |
|
|
else |
469 |
|
|
return (drops > 0) ? -drops : lag; |
470 |
dl |
1.1 |
} |
471 |
|
|
|
472 |
|
|
/** |
473 |
|
|
* Unless already closed, issues onComplete signals to current |
474 |
|
|
* subscribers, and disallows subsequent attempts to publish. |
475 |
|
|
*/ |
476 |
|
|
public void close() { |
477 |
|
|
if (!closed) { |
478 |
|
|
BufferedSubscription<T> b, next; |
479 |
jsr166 |
1.2 |
synchronized (this) { |
480 |
dl |
1.1 |
b = clients; |
481 |
|
|
clients = null; |
482 |
|
|
closed = true; |
483 |
|
|
} |
484 |
|
|
while (b != null) { |
485 |
|
|
next = b.next; |
486 |
dl |
1.19 |
b.onComplete(); |
487 |
dl |
1.1 |
b = next; |
488 |
|
|
} |
489 |
|
|
} |
490 |
|
|
} |
491 |
|
|
|
492 |
|
|
/** |
493 |
|
|
* Unless already closed, issues onError signals to current |
494 |
|
|
* subscribers with the given error, and disallows subsequent |
495 |
|
|
* attempts to publish. |
496 |
|
|
* |
497 |
jsr166 |
1.5 |
* @param error the onError argument sent to subscribers |
498 |
dl |
1.1 |
* @throws NullPointerException if error is null |
499 |
|
|
*/ |
500 |
|
|
public void closeExceptionally(Throwable error) { |
501 |
|
|
if (error == null) |
502 |
|
|
throw new NullPointerException(); |
503 |
|
|
if (!closed) { |
504 |
|
|
BufferedSubscription<T> b, next; |
505 |
jsr166 |
1.2 |
synchronized (this) { |
506 |
dl |
1.1 |
b = clients; |
507 |
|
|
clients = null; |
508 |
|
|
closed = true; |
509 |
|
|
} |
510 |
|
|
while (b != null) { |
511 |
|
|
next = b.next; |
512 |
dl |
1.19 |
b.onError(error); |
513 |
dl |
1.1 |
b = next; |
514 |
|
|
} |
515 |
|
|
} |
516 |
|
|
} |
517 |
|
|
|
518 |
|
|
/** |
519 |
|
|
* Returns true if this publisher is not accepting submissions. |
520 |
|
|
* |
521 |
|
|
* @return true if closed |
522 |
|
|
*/ |
523 |
|
|
public boolean isClosed() { |
524 |
|
|
return closed; |
525 |
|
|
} |
526 |
|
|
|
527 |
|
|
/** |
528 |
jsr166 |
1.6 |
* Returns true if this publisher has any subscribers. |
529 |
dl |
1.1 |
* |
530 |
|
|
* @return true if this publisher has any subscribers |
531 |
|
|
*/ |
532 |
|
|
public boolean hasSubscribers() { |
533 |
|
|
boolean nonEmpty = false; |
534 |
|
|
if (!closed) { |
535 |
jsr166 |
1.2 |
synchronized (this) { |
536 |
dl |
1.1 |
BufferedSubscription<T> pred = null, next; |
537 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
538 |
|
|
next = b.next; |
539 |
dl |
1.19 |
if (b.isDisabled()) { |
540 |
dl |
1.29 |
b.next = null; |
541 |
dl |
1.1 |
if (pred == null) |
542 |
|
|
clients = next; |
543 |
|
|
else |
544 |
|
|
pred.next = next; |
545 |
jsr166 |
1.2 |
} |
546 |
dl |
1.1 |
else { |
547 |
|
|
nonEmpty = true; |
548 |
|
|
break; |
549 |
|
|
} |
550 |
|
|
} |
551 |
|
|
} |
552 |
|
|
} |
553 |
|
|
return nonEmpty; |
554 |
|
|
} |
555 |
|
|
|
556 |
|
|
/** |
557 |
dl |
1.21 |
* Returns the number of current subscribers. |
558 |
dl |
1.1 |
* |
559 |
dl |
1.21 |
* @return the number of current subscribers |
560 |
dl |
1.1 |
*/ |
561 |
dl |
1.21 |
public int getNumberOfSubscribers() { |
562 |
|
|
int count = 0; |
563 |
|
|
if (!closed) { |
564 |
|
|
synchronized (this) { |
565 |
|
|
BufferedSubscription<T> pred = null, next; |
566 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
567 |
|
|
next = b.next; |
568 |
|
|
if (b.isDisabled()) { |
569 |
dl |
1.29 |
b.next = null; |
570 |
dl |
1.21 |
if (pred == null) |
571 |
|
|
clients = next; |
572 |
|
|
else |
573 |
|
|
pred.next = next; |
574 |
|
|
} |
575 |
|
|
else { |
576 |
|
|
pred = b; |
577 |
|
|
++count; |
578 |
|
|
} |
579 |
|
|
} |
580 |
|
|
} |
581 |
|
|
} |
582 |
|
|
return count; |
583 |
dl |
1.1 |
} |
584 |
|
|
|
585 |
jsr166 |
1.7 |
/** |
586 |
dl |
1.21 |
* Returns the Executor used for asynchronous delivery. |
587 |
dl |
1.1 |
* |
588 |
dl |
1.21 |
* @return the Executor used for asynchronous delivery |
589 |
dl |
1.1 |
*/ |
590 |
dl |
1.21 |
public Executor getExecutor() { |
591 |
|
|
return executor; |
592 |
dl |
1.1 |
} |
593 |
|
|
|
594 |
jsr166 |
1.7 |
/** |
595 |
jsr166 |
1.5 |
* Returns the maximum per-subscriber buffer capacity. |
596 |
dl |
1.1 |
* |
597 |
jsr166 |
1.5 |
* @return the maximum per-subscriber buffer capacity |
598 |
dl |
1.1 |
*/ |
599 |
|
|
public int getMaxBufferCapacity() { |
600 |
|
|
return maxBufferCapacity; |
601 |
|
|
} |
602 |
|
|
|
603 |
|
|
/** |
604 |
dl |
1.29 |
* Returns a list of current subscribers for monitoring and |
605 |
|
|
* tracking purposes, not for invoking {@link Flow.Subscriber} |
606 |
|
|
* methods on the subscribers. |
607 |
dl |
1.1 |
* |
608 |
|
|
* @return list of current subscribers |
609 |
|
|
*/ |
610 |
|
|
public List<Flow.Subscriber<? super T>> getSubscribers() { |
611 |
|
|
ArrayList<Flow.Subscriber<? super T>> subs = new ArrayList<>(); |
612 |
jsr166 |
1.2 |
synchronized (this) { |
613 |
dl |
1.1 |
BufferedSubscription<T> pred = null, next; |
614 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
615 |
|
|
next = b.next; |
616 |
dl |
1.19 |
if (b.isDisabled()) { |
617 |
dl |
1.29 |
b.next = null; |
618 |
dl |
1.1 |
if (pred == null) |
619 |
|
|
clients = next; |
620 |
|
|
else |
621 |
|
|
pred.next = next; |
622 |
jsr166 |
1.2 |
} |
623 |
dl |
1.1 |
else |
624 |
|
|
subs.add(b.subscriber); |
625 |
|
|
} |
626 |
|
|
} |
627 |
|
|
return subs; |
628 |
|
|
} |
629 |
jsr166 |
1.2 |
|
630 |
dl |
1.1 |
/** |
631 |
|
|
* Returns true if the given Subscriber is currently subscribed. |
632 |
|
|
* |
633 |
|
|
* @param subscriber the subscriber |
634 |
|
|
* @return true if currently subscribed |
635 |
dl |
1.21 |
* @throws NullPointerException if subscriber is null |
636 |
dl |
1.1 |
*/ |
637 |
|
|
public boolean isSubscribed(Flow.Subscriber<? super T> subscriber) { |
638 |
dl |
1.21 |
if (subscriber == null) throw new NullPointerException(); |
639 |
jsr166 |
1.2 |
if (!closed) { |
640 |
|
|
synchronized (this) { |
641 |
dl |
1.1 |
BufferedSubscription<T> pred = null, next; |
642 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
643 |
|
|
next = b.next; |
644 |
dl |
1.19 |
if (b.isDisabled()) { |
645 |
dl |
1.29 |
b.next = null; |
646 |
dl |
1.1 |
if (pred == null) |
647 |
|
|
clients = next; |
648 |
|
|
else |
649 |
|
|
pred.next = next; |
650 |
jsr166 |
1.2 |
} |
651 |
dl |
1.21 |
else if (subscriber.equals(b.subscriber)) |
652 |
dl |
1.1 |
return true; |
653 |
dl |
1.21 |
else |
654 |
|
|
pred = b; |
655 |
dl |
1.1 |
} |
656 |
|
|
} |
657 |
|
|
} |
658 |
|
|
return false; |
659 |
|
|
} |
660 |
|
|
|
661 |
|
|
/** |
662 |
dl |
1.21 |
* Returns an estimate of the minimum number of items requested |
663 |
|
|
* (via {@link Flow.Subscription#request}) but not yet produced, |
664 |
|
|
* among all current subscribers. |
665 |
|
|
* |
666 |
|
|
* @return the estimate, or zero if no subscribers |
667 |
|
|
*/ |
668 |
|
|
public long estimateMinimumDemand() { |
669 |
|
|
long min = Long.MAX_VALUE; |
670 |
|
|
boolean nonEmpty = false; |
671 |
|
|
synchronized (this) { |
672 |
|
|
BufferedSubscription<T> pred = null, next; |
673 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
674 |
|
|
int n; long d; |
675 |
|
|
next = b.next; |
676 |
|
|
if ((n = b.estimateLag()) < 0) { |
677 |
dl |
1.29 |
b.next = null; |
678 |
dl |
1.21 |
if (pred == null) |
679 |
|
|
clients = next; |
680 |
|
|
else |
681 |
|
|
pred.next = next; |
682 |
|
|
} |
683 |
|
|
else { |
684 |
|
|
if ((d = b.demand - n) < min) |
685 |
|
|
min = d; |
686 |
|
|
nonEmpty = true; |
687 |
|
|
} |
688 |
|
|
} |
689 |
|
|
} |
690 |
jsr166 |
1.22 |
return nonEmpty ? min : 0; |
691 |
dl |
1.21 |
} |
692 |
|
|
|
693 |
|
|
/** |
694 |
|
|
* Returns an estimate of the maximum number of items produced but |
695 |
|
|
* not yet consumed among all current subscribers. |
696 |
dl |
1.17 |
* |
697 |
|
|
* @return the estimate |
698 |
dl |
1.1 |
*/ |
699 |
dl |
1.21 |
public int estimateMaximumLag() { |
700 |
|
|
int max = 0; |
701 |
dl |
1.17 |
synchronized (this) { |
702 |
|
|
BufferedSubscription<T> pred = null, next; |
703 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
704 |
dl |
1.21 |
int n; |
705 |
dl |
1.17 |
next = b.next; |
706 |
dl |
1.21 |
if ((n = b.estimateLag()) < 0) { |
707 |
dl |
1.29 |
b.next = null; |
708 |
dl |
1.17 |
if (pred == null) |
709 |
|
|
clients = next; |
710 |
|
|
else |
711 |
|
|
pred.next = next; |
712 |
|
|
} |
713 |
dl |
1.21 |
else if (n > max) |
714 |
|
|
max = n; |
715 |
dl |
1.17 |
} |
716 |
|
|
} |
717 |
dl |
1.21 |
return max; |
718 |
dl |
1.1 |
} |
719 |
|
|
|
720 |
dl |
1.25 |
/** |
721 |
|
|
* A task for consuming buffer items and signals, created and |
722 |
|
|
* executed whenever they become available. A task consumes as |
723 |
|
|
* many items/signals as possible before terminating, at which |
724 |
|
|
* point another task is created when needed. The dual Runnable |
725 |
|
|
* and ForkJoinTask declaration saves overhead when executed by |
726 |
|
|
* ForkJoinPools, without impacting other kinds of Executors. |
727 |
|
|
*/ |
728 |
|
|
@SuppressWarnings("serial") |
729 |
|
|
static final class ConsumerTask<T> extends ForkJoinTask<Void> |
730 |
|
|
implements Runnable { |
731 |
|
|
final BufferedSubscription<T> consumer; |
732 |
|
|
ConsumerTask(BufferedSubscription<T> consumer) { |
733 |
|
|
this.consumer = consumer; |
734 |
|
|
} |
735 |
|
|
public final Void getRawResult() { return null; } |
736 |
|
|
public final void setRawResult(Void v) {} |
737 |
|
|
public final boolean exec() { consumer.consume(); return false; } |
738 |
|
|
public final void run() { consumer.consume(); } |
739 |
|
|
} |
740 |
|
|
|
741 |
dl |
1.1 |
/** |
742 |
dl |
1.15 |
* A bounded (ring) buffer with integrated control to start a |
743 |
|
|
* consumer task whenever items are available. The buffer |
744 |
dl |
1.1 |
* algorithm is similar to one used inside ForkJoinPool, |
745 |
|
|
* specialized for the case of at most one concurrent producer and |
746 |
|
|
* consumer, and power of two buffer sizes. This allows methods to |
747 |
|
|
* operate without locks even while supporting resizing, blocking, |
748 |
|
|
* task-triggering, and garbage-free buffers (nulling out elements |
749 |
|
|
* when consumed), although supporting these does impose a bit of |
750 |
|
|
* overhead compared to plain fixed-size ring buffers. |
751 |
|
|
* |
752 |
|
|
* The publisher guarantees a single producer via its lock. We |
753 |
|
|
* ensure in this class that there is at most one consumer. The |
754 |
|
|
* request and cancel methods must be fully thread-safe but are |
755 |
|
|
* coded to exploit the most common case in which they are only |
756 |
|
|
* called by consumers (usually within onNext). |
757 |
|
|
* |
758 |
dl |
1.15 |
* Execution control is managed using the ACTIVE ctl bit. We |
759 |
|
|
* ensure that a task is active when consumable items (and |
760 |
dl |
1.19 |
* usually, SUBSCRIBE, ERROR or COMPLETE signals) are present and |
761 |
dl |
1.24 |
* there is demand (unfilled requests). This is complicated on |
762 |
dl |
1.19 |
* the creation side by the possibility of exceptions when trying |
763 |
|
|
* to execute tasks. These eventually force DISABLED state, but |
764 |
dl |
1.1 |
* sometimes not directly. On the task side, termination (clearing |
765 |
dl |
1.27 |
* ACTIVE) that would otherwise race with producers or request() |
766 |
dl |
1.29 |
* calls uses the CONSUME keep-alive bit to force a recheck. |
767 |
dl |
1.1 |
* |
768 |
|
|
* The ctl field also manages run state. When DISABLED, no further |
769 |
dl |
1.20 |
* updates are possible. Disabling may be preceded by setting |
770 |
dl |
1.1 |
* ERROR or COMPLETE (or both -- ERROR has precedence), in which |
771 |
|
|
* case the associated Subscriber methods are invoked, possibly |
772 |
|
|
* synchronously if there is no active consumer task (including |
773 |
dl |
1.20 |
* cases where execute() failed). The cancel() method is supported |
774 |
|
|
* by treating as ERROR but suppressing onError signal. |
775 |
dl |
1.1 |
* |
776 |
|
|
* Support for blocking also exploits the fact that there is only |
777 |
|
|
* one possible waiter. ManagedBlocker-compatible control fields |
778 |
|
|
* are placed in this class itself rather than in wait-nodes. |
779 |
|
|
* Blocking control relies on the "waiter" field. Producers set |
780 |
|
|
* the field before trying to block, but must then recheck (via |
781 |
|
|
* offer) before parking. Signalling then just unparks and clears |
782 |
dl |
1.20 |
* waiter field. If the producer and consumer are both in the same |
783 |
dl |
1.29 |
* ForkJoinPool, or consumers are running in commonPool, the |
784 |
|
|
* producer attempts to help run consumer tasks that it forked |
785 |
|
|
* before blocking. To avoid potential cycles, only one level of |
786 |
|
|
* helping is currently supported. |
787 |
dl |
1.1 |
* |
788 |
|
|
* This class uses @Contended and heuristic field declaration |
789 |
|
|
* ordering to reduce memory contention on BufferedSubscription |
790 |
|
|
* itself, but it does not currently attempt to avoid memory |
791 |
|
|
* contention (especially including card-marks) among buffer |
792 |
|
|
* elements, that can significantly slow down some usages. |
793 |
|
|
* Addressing this may require allocating substantially more space |
794 |
|
|
* than users expect. |
795 |
|
|
*/ |
796 |
dl |
1.15 |
@SuppressWarnings("serial") |
797 |
dl |
1.1 |
@sun.misc.Contended |
798 |
dl |
1.25 |
static final class BufferedSubscription<T> |
799 |
|
|
implements Flow.Subscription, ForkJoinPool.ManagedBlocker { |
800 |
dl |
1.1 |
// Order-sensitive field declarations |
801 |
dl |
1.27 |
long timeout; // > 0 if timed wait |
802 |
|
|
volatile long demand; // # unfilled requests |
803 |
|
|
int maxCapacity; // reduced on OOME |
804 |
|
|
int putStat; // offer result for ManagedBlocker |
805 |
dl |
1.29 |
int helpDepth; // nested helping depth (at most 1) |
806 |
dl |
1.27 |
volatile int ctl; // atomic run state flags |
807 |
|
|
volatile int head; // next position to take |
808 |
|
|
volatile int tail; // next position to put |
809 |
|
|
Object[] array; // buffer: null if disabled |
810 |
dl |
1.1 |
Flow.Subscriber<? super T> subscriber; // null if disabled |
811 |
dl |
1.27 |
Executor executor; // null if disabled |
812 |
|
|
volatile Throwable pendingError; // holds until onError issued |
813 |
|
|
volatile Thread waiter; // blocked producer thread |
814 |
|
|
T putItem; // for offer within ManagedBlocker |
815 |
|
|
BufferedSubscription<T> next; // used only by publisher |
816 |
|
|
BufferedSubscription<T> nextRetry; // used only by publisher |
817 |
dl |
1.1 |
|
818 |
|
|
// ctl values |
819 |
dl |
1.20 |
static final int ACTIVE = 0x01; // consumer task active |
820 |
dl |
1.29 |
static final int CONSUME = 0x02; // keep-alive for consumer task |
821 |
dl |
1.27 |
static final int DISABLED = 0x04; // final state |
822 |
|
|
static final int ERROR = 0x08; // signal onError then disable |
823 |
|
|
static final int SUBSCRIBE = 0x10; // signal onSubscribe |
824 |
|
|
static final int COMPLETE = 0x20; // signal onComplete when done |
825 |
dl |
1.1 |
|
826 |
dl |
1.20 |
static final long INTERRUPTED = -1L; // timeout vs interrupt sentinel |
827 |
dl |
1.16 |
|
828 |
jsr166 |
1.22 |
/** |
829 |
dl |
1.21 |
* Initial/Minimum buffer capacity. Must be a power of two, at least 2. |
830 |
|
|
*/ |
831 |
|
|
static final int MINCAP = 8; |
832 |
|
|
|
833 |
dl |
1.1 |
BufferedSubscription(Flow.Subscriber<? super T> subscriber, |
834 |
dl |
1.21 |
Executor executor, int maxBufferCapacity) { |
835 |
dl |
1.1 |
this.subscriber = subscriber; |
836 |
|
|
this.executor = executor; |
837 |
|
|
this.maxCapacity = maxBufferCapacity; |
838 |
|
|
} |
839 |
|
|
|
840 |
dl |
1.19 |
final boolean isDisabled() { |
841 |
dl |
1.20 |
return ctl == DISABLED; |
842 |
|
|
} |
843 |
|
|
|
844 |
dl |
1.21 |
/** |
845 |
|
|
* Returns estimated number of buffered items, or -1 if |
846 |
|
|
* disabled |
847 |
|
|
*/ |
848 |
|
|
final int estimateLag() { |
849 |
dl |
1.20 |
int n; |
850 |
jsr166 |
1.22 |
return (ctl == DISABLED) ? -1 : ((n = tail - head) > 0) ? n : 0; |
851 |
dl |
1.19 |
} |
852 |
|
|
|
853 |
dl |
1.1 |
/** |
854 |
dl |
1.16 |
* Tries to add item and start consumer task if necessary. |
855 |
dl |
1.21 |
* @return -1 if disabled, 0 if dropped, else estimated lag |
856 |
dl |
1.1 |
*/ |
857 |
|
|
final int offer(T item) { |
858 |
|
|
Object[] a = array; |
859 |
dl |
1.27 |
int t = tail, size = t + 1 - head, stat, cap, i; |
860 |
|
|
if (a == null || (cap = a.length) < size || (i = t & (cap - 1)) < 0) |
861 |
|
|
stat = growAndAdd(a, item); |
862 |
|
|
else { |
863 |
dl |
1.16 |
a[i] = item; |
864 |
dl |
1.1 |
U.putOrderedInt(this, TAIL, t + 1); |
865 |
dl |
1.27 |
stat = size; |
866 |
dl |
1.1 |
} |
867 |
dl |
1.29 |
return (stat > 0 && |
868 |
|
|
(ctl & (ACTIVE | CONSUME)) != (ACTIVE | CONSUME)) ? |
869 |
dl |
1.27 |
startOnOffer(stat) : stat; |
870 |
|
|
} |
871 |
|
|
|
872 |
|
|
/** |
873 |
jsr166 |
1.28 |
* Tries to create or expand buffer, then adds item if possible. |
874 |
dl |
1.27 |
*/ |
875 |
|
|
private int growAndAdd(Object[] a, T item) { |
876 |
|
|
int cap, stat; |
877 |
|
|
if ((ctl & (ERROR | DISABLED)) != 0) { |
878 |
|
|
cap = 0; |
879 |
|
|
stat = -1; |
880 |
|
|
} |
881 |
|
|
else if (a == null) { |
882 |
|
|
cap = 0; |
883 |
|
|
stat = 1; |
884 |
|
|
} |
885 |
|
|
else if ((cap = a.length) >= maxCapacity) |
886 |
|
|
stat = 0; // cannot grow |
887 |
|
|
else |
888 |
|
|
stat = cap + 1; |
889 |
|
|
if (stat > 0) { |
890 |
|
|
int newCap = (cap > 0 ? cap << 1 : |
891 |
|
|
maxCapacity >= MINCAP ? MINCAP : |
892 |
|
|
maxCapacity >= 2 ? maxCapacity : 2); |
893 |
|
|
if (newCap <= cap) |
894 |
|
|
stat = 0; |
895 |
|
|
else { |
896 |
|
|
Object[] newArray = null; |
897 |
dl |
1.16 |
try { |
898 |
dl |
1.27 |
newArray = new Object[newCap]; |
899 |
|
|
} catch (Throwable ex) { // try to cope with OOME |
900 |
|
|
} |
901 |
|
|
if (newArray == null) { |
902 |
|
|
if (cap > 0) |
903 |
|
|
maxCapacity = cap; // avoid continuous failure |
904 |
|
|
stat = 0; |
905 |
|
|
} |
906 |
|
|
else { |
907 |
|
|
array = newArray; |
908 |
|
|
int t = tail; |
909 |
|
|
int newMask = newCap - 1; |
910 |
|
|
if (a != null && cap > 0) { |
911 |
|
|
int mask = cap - 1; |
912 |
|
|
for (int j = head; j != t; ++j) { |
913 |
|
|
Object x; // races with consumer |
914 |
|
|
int k = j & mask; |
915 |
|
|
if ((x = a[k]) != null && |
916 |
|
|
U.compareAndSwapObject( |
917 |
|
|
a, (((long)k) << ASHIFT) + ABASE, |
918 |
|
|
x, null)) |
919 |
|
|
newArray[j & newMask] = x; |
920 |
|
|
} |
921 |
|
|
} |
922 |
|
|
newArray[t & newMask] = item; |
923 |
|
|
tail = t + 1; |
924 |
dl |
1.16 |
} |
925 |
|
|
} |
926 |
|
|
} |
927 |
dl |
1.21 |
return stat; |
928 |
dl |
1.1 |
} |
929 |
|
|
|
930 |
|
|
/** |
931 |
dl |
1.27 |
* Spins/helps/blocks while offer returns 0. Called only if |
932 |
dl |
1.29 |
* initial offer return 0. |
933 |
dl |
1.20 |
*/ |
934 |
|
|
final int submit(T item) { |
935 |
dl |
1.29 |
int stat = 0; |
936 |
dl |
1.27 |
Executor e = executor; |
937 |
dl |
1.29 |
if (helpDepth == 0 && (e instanceof ForkJoinPool)) { |
938 |
|
|
Thread thread = Thread.currentThread(); |
939 |
|
|
// split cases to help compiler specialization |
940 |
dl |
1.20 |
if ((thread instanceof ForkJoinWorkerThread) && |
941 |
dl |
1.25 |
((ForkJoinWorkerThread)thread).getPool() == e) { |
942 |
|
|
ForkJoinTask<?> t; |
943 |
|
|
while ((t = ForkJoinTask.peekNextLocalTask()) != null && |
944 |
|
|
(t instanceof ConsumerTask)) { |
945 |
|
|
if ((stat = offer(item)) != 0 || !t.tryUnfork()) |
946 |
dl |
1.20 |
break; |
947 |
dl |
1.29 |
((ConsumerTask<?>)t).consumer.helpConsume(); |
948 |
dl |
1.20 |
} |
949 |
|
|
} |
950 |
dl |
1.25 |
else if (e == ForkJoinPool.commonPool()) { |
951 |
|
|
ForkJoinTask<?> t; |
952 |
|
|
while ((t = ForkJoinTask.peekNextLocalTask()) != null && |
953 |
|
|
(t instanceof ConsumerTask)) { |
954 |
|
|
if ((stat = offer(item)) != 0 || !t.tryUnfork()) |
955 |
|
|
break; |
956 |
dl |
1.29 |
((ConsumerTask<?>)t).consumer.helpConsume(); |
957 |
dl |
1.20 |
} |
958 |
|
|
} |
959 |
|
|
} |
960 |
dl |
1.25 |
if (stat == 0 && (stat = offer(item)) == 0) { |
961 |
|
|
putItem = item; |
962 |
|
|
timeout = 0L; |
963 |
|
|
try { |
964 |
|
|
ForkJoinPool.managedBlock(this); |
965 |
|
|
} catch (InterruptedException ie) { |
966 |
|
|
timeout = INTERRUPTED; |
967 |
|
|
} |
968 |
|
|
stat = putStat; |
969 |
|
|
if (timeout < 0L) |
970 |
|
|
Thread.currentThread().interrupt(); |
971 |
|
|
} |
972 |
dl |
1.20 |
return stat; |
973 |
|
|
} |
974 |
|
|
|
975 |
|
|
/** |
976 |
dl |
1.27 |
* Timeout version; similar to submit |
977 |
dl |
1.20 |
*/ |
978 |
dl |
1.27 |
final int timedOffer(T item, long nanos) { |
979 |
dl |
1.29 |
int stat = 0; |
980 |
dl |
1.27 |
Executor e = executor; |
981 |
dl |
1.29 |
if (helpDepth == 0 && (e instanceof ForkJoinPool)) { |
982 |
|
|
Thread thread = Thread.currentThread(); |
983 |
|
|
if (((thread instanceof ForkJoinWorkerThread) && |
984 |
|
|
((ForkJoinWorkerThread)thread).getPool() == e) || |
985 |
|
|
e == ForkJoinPool.commonPool()) { |
986 |
|
|
ForkJoinTask<?> t; |
987 |
|
|
long deadline = System.nanoTime() + nanos; |
988 |
|
|
while ((t = ForkJoinTask.peekNextLocalTask()) != null && |
989 |
|
|
(t instanceof ConsumerTask)) { |
990 |
|
|
if ((stat = offer(item)) != 0 || |
991 |
|
|
(nanos = deadline - System.nanoTime()) <= 0L || |
992 |
|
|
!t.tryUnfork()) |
993 |
|
|
break; |
994 |
|
|
((ConsumerTask<?>)t).consumer.helpConsume(); |
995 |
|
|
} |
996 |
dl |
1.20 |
} |
997 |
dl |
1.25 |
} |
998 |
|
|
if (stat == 0 && (stat = offer(item)) == 0 && |
999 |
|
|
(timeout = nanos) > 0L) { |
1000 |
|
|
putItem = item; |
1001 |
|
|
try { |
1002 |
|
|
ForkJoinPool.managedBlock(this); |
1003 |
|
|
} catch (InterruptedException ie) { |
1004 |
|
|
timeout = INTERRUPTED; |
1005 |
|
|
} |
1006 |
|
|
stat = putStat; |
1007 |
|
|
if (timeout < 0L) |
1008 |
|
|
Thread.currentThread().interrupt(); |
1009 |
dl |
1.20 |
} |
1010 |
|
|
return stat; |
1011 |
|
|
} |
1012 |
|
|
|
1013 |
dl |
1.29 |
/** Version of consume called when helping in submit or timedOffer */ |
1014 |
|
|
private void helpConsume() { |
1015 |
|
|
helpDepth = 1; // only one level allowed |
1016 |
|
|
consume(); |
1017 |
|
|
helpDepth = 0; |
1018 |
|
|
} |
1019 |
|
|
|
1020 |
dl |
1.20 |
/** |
1021 |
dl |
1.27 |
* Tries to start consumer task after offer. |
1022 |
|
|
* @return -1 if now disabled, else argument |
1023 |
|
|
*/ |
1024 |
|
|
private int startOnOffer(int stat) { |
1025 |
|
|
for (;;) { |
1026 |
|
|
Executor e; int c; |
1027 |
|
|
if ((c = ctl) == DISABLED || (e = executor) == null) { |
1028 |
|
|
stat = -1; |
1029 |
|
|
break; |
1030 |
|
|
} |
1031 |
|
|
else if ((c & ACTIVE) != 0) { // ensure keep-alive |
1032 |
dl |
1.29 |
if ((c & CONSUME) != 0 || |
1033 |
dl |
1.27 |
U.compareAndSwapInt(this, CTL, c, |
1034 |
dl |
1.29 |
c | CONSUME)) |
1035 |
dl |
1.27 |
break; |
1036 |
|
|
} |
1037 |
|
|
else if (demand == 0L || tail == head) |
1038 |
|
|
break; |
1039 |
|
|
else if (U.compareAndSwapInt(this, CTL, c, |
1040 |
dl |
1.29 |
c | (ACTIVE | CONSUME))) { |
1041 |
dl |
1.27 |
try { |
1042 |
|
|
e.execute(new ConsumerTask<T>(this)); |
1043 |
|
|
break; |
1044 |
|
|
} catch (RuntimeException | Error ex) { // back out |
1045 |
|
|
do {} while ((c = ctl) >= 0 && |
1046 |
|
|
(c & ACTIVE) != 0 && |
1047 |
|
|
!U.compareAndSwapInt(this, CTL, c, |
1048 |
|
|
c & ~ACTIVE)); |
1049 |
|
|
throw ex; |
1050 |
|
|
} |
1051 |
|
|
} |
1052 |
|
|
} |
1053 |
|
|
return stat; |
1054 |
|
|
} |
1055 |
|
|
|
1056 |
|
|
/** |
1057 |
dl |
1.16 |
* Nulls out most fields, mainly to avoid garbage retention |
1058 |
dl |
1.20 |
* until publisher unsubscribes, but also to help cleanly stop |
1059 |
|
|
* upon error by nulling required components. |
1060 |
dl |
1.1 |
*/ |
1061 |
dl |
1.27 |
private void detach() { |
1062 |
|
|
Thread w = waiter; |
1063 |
|
|
array = null; |
1064 |
|
|
executor = null; |
1065 |
|
|
subscriber = null; |
1066 |
dl |
1.16 |
pendingError = null; |
1067 |
dl |
1.27 |
waiter = null; |
1068 |
|
|
if (w != null) |
1069 |
dl |
1.16 |
LockSupport.unpark(w); // force wakeup |
1070 |
dl |
1.1 |
} |
1071 |
|
|
|
1072 |
|
|
/** |
1073 |
dl |
1.19 |
* Issues error signal, asynchronously if a task is running, |
1074 |
jsr166 |
1.26 |
* else synchronously. |
1075 |
dl |
1.19 |
*/ |
1076 |
|
|
final void onError(Throwable ex) { |
1077 |
|
|
for (int c;;) { |
1078 |
dl |
1.29 |
if (((c = ctl) & (ERROR | DISABLED)) != 0) |
1079 |
dl |
1.19 |
break; |
1080 |
|
|
else if ((c & ACTIVE) != 0) { |
1081 |
|
|
pendingError = ex; |
1082 |
|
|
if (U.compareAndSwapInt(this, CTL, c, c | ERROR)) |
1083 |
|
|
break; // cause consumer task to exit |
1084 |
|
|
} |
1085 |
|
|
else if (U.compareAndSwapInt(this, CTL, c, DISABLED)) { |
1086 |
|
|
Flow.Subscriber<? super T> s = subscriber; |
1087 |
|
|
if (s != null && ex != null) { |
1088 |
|
|
try { |
1089 |
|
|
s.onError(ex); |
1090 |
|
|
} catch (Throwable ignore) { |
1091 |
|
|
} |
1092 |
|
|
} |
1093 |
|
|
detach(); |
1094 |
|
|
break; |
1095 |
|
|
} |
1096 |
|
|
} |
1097 |
|
|
} |
1098 |
|
|
|
1099 |
|
|
/** |
1100 |
dl |
1.1 |
* Tries to start consumer task upon a signal or request; |
1101 |
jsr166 |
1.12 |
* disables on failure. |
1102 |
dl |
1.1 |
*/ |
1103 |
dl |
1.27 |
private void startOrDisable() { |
1104 |
|
|
Executor e; |
1105 |
|
|
if ((e = executor) != null) { // skip if already disabled |
1106 |
dl |
1.1 |
try { |
1107 |
dl |
1.25 |
e.execute(new ConsumerTask<T>(this)); |
1108 |
dl |
1.27 |
} catch (Throwable ex) { // back out and force signal |
1109 |
dl |
1.1 |
for (int c;;) { |
1110 |
dl |
1.20 |
if ((c = ctl) == DISABLED || (c & ACTIVE) == 0) |
1111 |
dl |
1.1 |
break; |
1112 |
|
|
if (U.compareAndSwapInt(this, CTL, c, c & ~ACTIVE)) { |
1113 |
dl |
1.19 |
onError(ex); |
1114 |
dl |
1.1 |
break; |
1115 |
|
|
} |
1116 |
|
|
} |
1117 |
|
|
} |
1118 |
|
|
} |
1119 |
|
|
} |
1120 |
|
|
|
1121 |
dl |
1.19 |
final void onComplete() { |
1122 |
dl |
1.1 |
for (int c;;) { |
1123 |
dl |
1.20 |
if ((c = ctl) == DISABLED) |
1124 |
dl |
1.1 |
break; |
1125 |
dl |
1.27 |
if (U.compareAndSwapInt(this, CTL, c, |
1126 |
dl |
1.29 |
c | (ACTIVE | CONSUME | COMPLETE))) { |
1127 |
dl |
1.16 |
if ((c & ACTIVE) == 0) |
1128 |
|
|
startOrDisable(); |
1129 |
dl |
1.1 |
break; |
1130 |
|
|
} |
1131 |
|
|
} |
1132 |
|
|
} |
1133 |
|
|
|
1134 |
dl |
1.19 |
final void onSubscribe() { |
1135 |
dl |
1.1 |
for (int c;;) { |
1136 |
dl |
1.20 |
if ((c = ctl) == DISABLED) |
1137 |
dl |
1.1 |
break; |
1138 |
dl |
1.27 |
if (U.compareAndSwapInt(this, CTL, c, |
1139 |
dl |
1.29 |
c | (ACTIVE | CONSUME | SUBSCRIBE))) { |
1140 |
dl |
1.19 |
if ((c & ACTIVE) == 0) |
1141 |
|
|
startOrDisable(); |
1142 |
dl |
1.1 |
break; |
1143 |
|
|
} |
1144 |
|
|
} |
1145 |
|
|
} |
1146 |
|
|
|
1147 |
dl |
1.16 |
/** |
1148 |
|
|
* Causes consumer task to exit if active (without reporting |
1149 |
|
|
* onError unless there is already a pending error), and |
1150 |
|
|
* disables. |
1151 |
|
|
*/ |
1152 |
|
|
public void cancel() { |
1153 |
dl |
1.1 |
for (int c;;) { |
1154 |
dl |
1.20 |
if ((c = ctl) == DISABLED) |
1155 |
dl |
1.1 |
break; |
1156 |
dl |
1.16 |
else if ((c & ACTIVE) != 0) { |
1157 |
dl |
1.29 |
if (U.compareAndSwapInt(this, CTL, c, |
1158 |
|
|
c | (CONSUME | ERROR))) |
1159 |
dl |
1.16 |
break; |
1160 |
|
|
} |
1161 |
|
|
else if (U.compareAndSwapInt(this, CTL, c, DISABLED)) { |
1162 |
|
|
detach(); |
1163 |
dl |
1.1 |
break; |
1164 |
|
|
} |
1165 |
|
|
} |
1166 |
|
|
} |
1167 |
|
|
|
1168 |
dl |
1.16 |
/** |
1169 |
|
|
* Adds to demand and possibly starts task. |
1170 |
|
|
*/ |
1171 |
|
|
public void request(long n) { |
1172 |
|
|
if (n > 0L) { |
1173 |
|
|
for (;;) { |
1174 |
|
|
long prev = demand, d; |
1175 |
|
|
if ((d = prev + n) < prev) // saturate |
1176 |
|
|
d = Long.MAX_VALUE; |
1177 |
|
|
if (U.compareAndSwapLong(this, DEMAND, prev, d)) { |
1178 |
dl |
1.27 |
while (d != 0L) { |
1179 |
|
|
int c, h; |
1180 |
|
|
if ((c = ctl) == DISABLED) |
1181 |
dl |
1.16 |
break; |
1182 |
dl |
1.27 |
else if ((c & ACTIVE) != 0) { |
1183 |
dl |
1.29 |
if ((c & CONSUME) != 0 || |
1184 |
dl |
1.27 |
U.compareAndSwapInt(this, CTL, c, |
1185 |
dl |
1.29 |
c | CONSUME)) |
1186 |
dl |
1.27 |
break; |
1187 |
|
|
} |
1188 |
|
|
else if ((h = head) != tail) { |
1189 |
dl |
1.16 |
if (U.compareAndSwapInt(this, CTL, c, |
1190 |
dl |
1.29 |
c | (ACTIVE|CONSUME))) { |
1191 |
dl |
1.16 |
startOrDisable(); |
1192 |
|
|
break; |
1193 |
|
|
} |
1194 |
|
|
} |
1195 |
|
|
else if (head == h && tail == h) |
1196 |
dl |
1.27 |
break; // else stale |
1197 |
|
|
d = demand; |
1198 |
dl |
1.16 |
} |
1199 |
|
|
break; |
1200 |
|
|
} |
1201 |
|
|
} |
1202 |
|
|
} |
1203 |
|
|
else if (n < 0L) |
1204 |
dl |
1.19 |
onError(new IllegalArgumentException( |
1205 |
|
|
"negative subscription request")); |
1206 |
dl |
1.16 |
} |
1207 |
|
|
|
1208 |
dl |
1.20 |
public final boolean isReleasable() { // for ManagedBlocker |
1209 |
dl |
1.1 |
T item = putItem; |
1210 |
dl |
1.25 |
if (item != null) { // A few randomized spins |
1211 |
|
|
for (int spins = MINCAP, r = 0;;) { |
1212 |
|
|
if ((putStat = offer(item)) != 0) { |
1213 |
|
|
putItem = null; |
1214 |
|
|
break; |
1215 |
|
|
} |
1216 |
|
|
else if (r == 0) |
1217 |
|
|
r = ThreadLocalRandom.nextSecondarySeed(); |
1218 |
|
|
else { |
1219 |
|
|
r ^= r << 6; r ^= r >>> 21; r ^= r << 7; // xorshift |
1220 |
|
|
if (r >= 0 && --spins <= 0) |
1221 |
|
|
return false; |
1222 |
|
|
} |
1223 |
|
|
} |
1224 |
dl |
1.1 |
} |
1225 |
|
|
return true; |
1226 |
|
|
} |
1227 |
|
|
|
1228 |
dl |
1.20 |
public final boolean block() { // for ManagedBlocker |
1229 |
dl |
1.1 |
T item = putItem; |
1230 |
|
|
if (item != null) { |
1231 |
|
|
putItem = null; |
1232 |
|
|
long nanos = timeout; |
1233 |
|
|
long deadline = (nanos > 0L) ? System.nanoTime() + nanos : 0L; |
1234 |
|
|
while ((putStat = offer(item)) == 0) { |
1235 |
|
|
if (Thread.interrupted()) { |
1236 |
dl |
1.16 |
timeout = INTERRUPTED; |
1237 |
dl |
1.1 |
if (nanos > 0L) |
1238 |
|
|
break; |
1239 |
|
|
} |
1240 |
|
|
else if (nanos > 0L && |
1241 |
|
|
(nanos = deadline - System.nanoTime()) <= 0L) |
1242 |
|
|
break; |
1243 |
|
|
else if (waiter == null) |
1244 |
|
|
waiter = Thread.currentThread(); |
1245 |
|
|
else { |
1246 |
|
|
if (nanos > 0L) |
1247 |
|
|
LockSupport.parkNanos(this, nanos); |
1248 |
|
|
else |
1249 |
|
|
LockSupport.park(this); |
1250 |
|
|
waiter = null; |
1251 |
|
|
} |
1252 |
|
|
} |
1253 |
|
|
} |
1254 |
|
|
waiter = null; |
1255 |
|
|
return true; |
1256 |
|
|
} |
1257 |
|
|
|
1258 |
dl |
1.29 |
/** |
1259 |
|
|
* Consumer loop, called from ConsumerTask, or indirectly |
1260 |
|
|
* via helpConsume when helping during submit. |
1261 |
|
|
*/ |
1262 |
dl |
1.25 |
final void consume() { |
1263 |
dl |
1.1 |
Flow.Subscriber<? super T> s; |
1264 |
dl |
1.27 |
if ((s = subscriber) != null) { // else disabled |
1265 |
|
|
for (int h = head;;) { |
1266 |
|
|
long d = demand; |
1267 |
|
|
int c, n, i; Object[] a; Object x; Thread w; |
1268 |
|
|
if (((c = ctl) & (ERROR | SUBSCRIBE | DISABLED)) != 0) { |
1269 |
dl |
1.20 |
if ((c & ERROR) != 0) { |
1270 |
|
|
Throwable ex = pendingError; |
1271 |
dl |
1.27 |
ctl = DISABLED; // no need for CAS |
1272 |
|
|
if (ex != null) { // null if errorless cancel |
1273 |
dl |
1.20 |
try { |
1274 |
|
|
s.onError(ex); |
1275 |
|
|
} catch (Throwable ignore) { |
1276 |
|
|
} |
1277 |
dl |
1.1 |
} |
1278 |
|
|
} |
1279 |
dl |
1.20 |
else if ((c & SUBSCRIBE) != 0) { |
1280 |
|
|
if (U.compareAndSwapInt(this, CTL, c, |
1281 |
|
|
c & ~SUBSCRIBE)) { |
1282 |
|
|
try { |
1283 |
|
|
s.onSubscribe(this); |
1284 |
|
|
} catch (Throwable ex) { |
1285 |
dl |
1.29 |
onError(ex); |
1286 |
dl |
1.20 |
} |
1287 |
dl |
1.19 |
} |
1288 |
|
|
} |
1289 |
dl |
1.20 |
else { |
1290 |
|
|
detach(); |
1291 |
|
|
break; |
1292 |
|
|
} |
1293 |
dl |
1.19 |
} |
1294 |
dl |
1.27 |
else if (h == tail) { // apparently empty |
1295 |
dl |
1.29 |
if ((c & CONSUME) != 0) // recheck |
1296 |
|
|
U.compareAndSwapInt(this, CTL, c, c & ~CONSUME); |
1297 |
dl |
1.27 |
else if ((c & COMPLETE) != 0) { |
1298 |
dl |
1.29 |
if (U.compareAndSwapInt(this, CTL, c, DISABLED)) { |
1299 |
|
|
try { |
1300 |
|
|
s.onComplete(); |
1301 |
|
|
} catch (Throwable ignore) { |
1302 |
|
|
} |
1303 |
dl |
1.1 |
} |
1304 |
dl |
1.27 |
} |
1305 |
|
|
else if (U.compareAndSwapInt(this, CTL, c, |
1306 |
|
|
c & ~ACTIVE)) |
1307 |
|
|
break; |
1308 |
|
|
} |
1309 |
|
|
else if (d == 0L) { // can't consume |
1310 |
|
|
if (demand == 0L) { // recheck |
1311 |
dl |
1.29 |
if ((c & CONSUME) != 0) |
1312 |
dl |
1.27 |
U.compareAndSwapInt(this, CTL, c, |
1313 |
dl |
1.29 |
c & ~CONSUME); |
1314 |
dl |
1.27 |
else if (U.compareAndSwapInt(this, CTL, c, |
1315 |
|
|
c & ~ACTIVE)) |
1316 |
dl |
1.1 |
break; |
1317 |
|
|
} |
1318 |
|
|
} |
1319 |
dl |
1.27 |
else if ((a = array) == null || (n = a.length) == 0 || |
1320 |
dl |
1.16 |
(x = a[i = h & (n - 1)]) == null) |
1321 |
dl |
1.27 |
; // stale; retry |
1322 |
dl |
1.29 |
else if ((c & CONSUME) == 0) |
1323 |
|
|
U.compareAndSwapInt(this, CTL, c, c | CONSUME); |
1324 |
dl |
1.16 |
else if (U.compareAndSwapObject( |
1325 |
dl |
1.1 |
a, (((long)i) << ASHIFT) + ABASE, x, null)) { |
1326 |
dl |
1.27 |
U.putOrderedInt(this, HEAD, ++h); |
1327 |
dl |
1.1 |
while (!U.compareAndSwapLong(this, DEMAND, d, d - 1L)) |
1328 |
dl |
1.27 |
d = demand; // almost never fails |
1329 |
dl |
1.1 |
if ((w = waiter) != null) { |
1330 |
|
|
waiter = null; |
1331 |
dl |
1.27 |
LockSupport.unpark(w); // release producer |
1332 |
dl |
1.1 |
} |
1333 |
|
|
try { |
1334 |
|
|
@SuppressWarnings("unchecked") T y = (T) x; |
1335 |
|
|
s.onNext(y); |
1336 |
dl |
1.29 |
} catch (Throwable ex) { |
1337 |
|
|
onError(ex); |
1338 |
dl |
1.1 |
} |
1339 |
|
|
} |
1340 |
|
|
} |
1341 |
|
|
} |
1342 |
|
|
} |
1343 |
|
|
|
1344 |
jsr166 |
1.9 |
// Unsafe mechanics |
1345 |
|
|
private static final sun.misc.Unsafe U = sun.misc.Unsafe.getUnsafe(); |
1346 |
dl |
1.1 |
private static final long CTL; |
1347 |
|
|
private static final long TAIL; |
1348 |
|
|
private static final long HEAD; |
1349 |
|
|
private static final long DEMAND; |
1350 |
|
|
private static final int ABASE; |
1351 |
|
|
private static final int ASHIFT; |
1352 |
|
|
|
1353 |
|
|
static { |
1354 |
|
|
try { |
1355 |
|
|
CTL = U.objectFieldOffset |
1356 |
jsr166 |
1.9 |
(BufferedSubscription.class.getDeclaredField("ctl")); |
1357 |
dl |
1.1 |
TAIL = U.objectFieldOffset |
1358 |
jsr166 |
1.9 |
(BufferedSubscription.class.getDeclaredField("tail")); |
1359 |
dl |
1.1 |
HEAD = U.objectFieldOffset |
1360 |
jsr166 |
1.9 |
(BufferedSubscription.class.getDeclaredField("head")); |
1361 |
dl |
1.1 |
DEMAND = U.objectFieldOffset |
1362 |
jsr166 |
1.9 |
(BufferedSubscription.class.getDeclaredField("demand")); |
1363 |
|
|
|
1364 |
|
|
ABASE = U.arrayBaseOffset(Object[].class); |
1365 |
|
|
int scale = U.arrayIndexScale(Object[].class); |
1366 |
dl |
1.1 |
if ((scale & (scale - 1)) != 0) |
1367 |
|
|
throw new Error("data type scale not a power of two"); |
1368 |
|
|
ASHIFT = 31 - Integer.numberOfLeadingZeros(scale); |
1369 |
jsr166 |
1.9 |
} catch (ReflectiveOperationException e) { |
1370 |
dl |
1.1 |
throw new Error(e); |
1371 |
|
|
} |
1372 |
|
|
} |
1373 |
|
|
} |
1374 |
|
|
} |