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dl |
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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dl |
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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dl |
1.15 |
import java.util.function.Supplier; |
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dl |
1.1 |
|
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/** |
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* A {@link Flow.Publisher} that asynchronously issues submitted items |
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* to current subscribers until it is closed. Each current subscriber |
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* receives newly submitted items in the same order unless drops or |
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* exceptions are encountered. Using a SubmissionPublisher allows |
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* item generators to act as Publishers, although without integrated |
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* flow control. Instead they rely on drop handling and/or blocking. |
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* |
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dl |
1.16 |
* <p>A SubmissionPublisher uses the {@link Executor} supplied in its |
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dl |
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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* Executors#newFixedThreadPool}. Otherwise consider using a |
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* work-stealing pool (including {@link ForkJoinPool#commonPool}). |
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* |
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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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* Buffers are created upon first use with a given initial capacity, |
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* and are resized as needed up to the maximum. (Capacity arguments |
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dl |
1.16 |
* may be rounded up to powers of two.) Invocations of {@link |
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* Flow.Subscription#request} do not directly result in buffer |
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* expansion, but risk saturation if unfulfilled requests exceed the |
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* maximum capacity. Choices of buffer parameters rely on expected |
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* rates, resources, and usages, that usually benefit from empirical |
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* testing. As first guesses, consider initial 8 and maximum 1024. |
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dl |
1.1 |
* |
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* <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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dl |
1.16 |
* resources are available. This is simplest, but least |
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* responsive. The {@code offer} methods may either immediately, or |
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* with bounded timeout, drop items, but provide an opportunity to |
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* interpose a handler and then retry. |
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dl |
1.1 |
* |
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* <p>If any Subscriber method throws an exception, its subscription |
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* is cancelled. If the supplied Executor throws |
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* RejectedExecutionException (or any other RuntimeException or Error) |
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* when attempting to execute a task, or a drop handler throws an |
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* exception when processing a dropped item, then the exception is |
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* rethrown. In these cases, some but not all subscribers may have |
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* received items. It is usually good practice to {@link |
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jsr166 |
1.11 |
* #closeExceptionally closeExceptionally} in these cases. |
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dl |
1.1 |
* |
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dl |
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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dl |
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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dl |
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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* PeriodicPublisher(Executor executor, int initialBufferCapacity, |
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* int maxBufferCapacity, Supplier<? extends T> supplier, |
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* long period, TimeUnit unit) { |
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* super(executor, initialBufferCapacity, maxBufferCapacity); |
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* 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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1.16 |
* <p>Here is an example of {@link Flow.Processor} subclass (using |
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* single-step requests to its publisher, for simplicity of |
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* illustration): |
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* |
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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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* TransformProcessor(Executor executor, int initialBufferCapacity, |
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* int maxBufferCapacity, |
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* Function<? super S, ? extends T> function) { |
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* super(executor, initialBufferCapacity, maxBufferCapacity); |
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* 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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dl |
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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* mainly ensures sequentiality by using built-in synchronization |
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* locks across public methods. (Using built-in locks works well |
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* in the most typical case in which only one thread submits |
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* items). |
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*/ |
125 |
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// Ensuring that all arrays have power of two length |
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static final int MAXIMUM_BUFFER_CAPACITY = 1 << 30; |
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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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return (n < 0) ? 1 : |
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(n >= MAXIMUM_BUFFER_CAPACITY) ? MAXIMUM_BUFFER_CAPACITY : n + 1; |
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} |
139 |
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140 |
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/** |
141 |
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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. |
143 |
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* It requires O(n) traversal to check for duplicate subscribers, |
144 |
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* but we expect that subscribing is much less common than |
145 |
dl |
1.13 |
* publishing. Unsubscribing occurs only during traversal loops, |
146 |
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* when BufferedSubscription methods or status checks return |
147 |
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* negative values signifying that they have been disabled. |
148 |
dl |
1.1 |
*/ |
149 |
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BufferedSubscription<T> clients; |
150 |
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// Parameters for constructing BufferedSubscriptions |
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final Executor executor; |
153 |
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final int minBufferCapacity; |
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final int maxBufferCapacity; |
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156 |
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/** Run status, updated only within locks */ |
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volatile boolean closed; |
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159 |
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/** |
160 |
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* Creates a new SubmissionPublisher using the given Executor for |
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* async delivery to subscribers, and with the given initial and |
162 |
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* maximum buffer sizes for each subscriber. In the absence of |
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* other constraints, consider using {@code |
164 |
jsr166 |
1.5 |
* ForkJoinPool.commonPool(), 8, 1024}. |
165 |
dl |
1.1 |
* |
166 |
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* @param executor the executor to use for async delivery, |
167 |
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* supporting creation of at least one independent thread |
168 |
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* @param initialBufferCapacity the initial capacity for each |
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* subscriber's buffer (the actual capacity may be rounded up to |
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* the nearest power of two) |
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* @param maxBufferCapacity the maximum capacity for each |
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* subscriber's buffer (the actual capacity may be rounded up to |
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* the nearest power of two) |
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* @throws NullPointerException if executor is null |
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* @throws IllegalArgumentException if initialBufferCapacity is |
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* not positive or exceeds maxBufferCapacity, or maxBufferCapacity |
177 |
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* exceeds {@code 1<<30} (about 1 billion), the maximum bound for |
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* a power of two array size |
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*/ |
180 |
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public SubmissionPublisher(Executor executor, |
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int initialBufferCapacity, |
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int maxBufferCapacity) { |
183 |
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if (executor == null) |
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throw new NullPointerException(); |
185 |
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if (initialBufferCapacity <= 0 || maxBufferCapacity <= 0) |
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throw new IllegalArgumentException("capacity must be positive"); |
187 |
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if (maxBufferCapacity > MAXIMUM_BUFFER_CAPACITY) |
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throw new IllegalArgumentException("capacity exceeds limit"); |
189 |
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if (initialBufferCapacity > maxBufferCapacity) |
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throw new IllegalArgumentException("initial cannot exceed max capacity"); |
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int minc = roundCapacity(initialBufferCapacity); |
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int maxc = roundCapacity(maxBufferCapacity); |
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this.executor = executor; |
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this.minBufferCapacity = minc; |
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this.maxBufferCapacity = maxc; |
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} |
197 |
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/** |
199 |
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* 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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* with an IllegalStateException. Otherwise, upon success, the |
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* Subscriber's onSubscribe method is invoked with a new |
203 |
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* Subscription (upon exception, the exception is rethrown and the |
204 |
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* Subscriber remains unsubscribed). If this SubmissionPublisher |
205 |
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* is closed, the subscriber's onComplete method is then invoked. |
206 |
dl |
1.13 |
* Subscribers may enable receiving items by invoking the {@code |
207 |
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* request} method of the new Subscription, and may unsubscribe by |
208 |
dl |
1.1 |
* invoking its cancel method. |
209 |
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* |
210 |
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* @param subscriber the subscriber |
211 |
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* @throws NullPointerException if subscriber is null |
212 |
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*/ |
213 |
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public void subscribe(Flow.Subscriber<? super T> subscriber) { |
214 |
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if (subscriber == null) throw new NullPointerException(); |
215 |
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BufferedSubscription<T> sub = new BufferedSubscription<T>( |
216 |
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subscriber, executor, minBufferCapacity, maxBufferCapacity); |
217 |
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boolean present = false, clsd; |
218 |
jsr166 |
1.2 |
synchronized (this) { |
219 |
dl |
1.1 |
BufferedSubscription<T> pred = null, next; |
220 |
dl |
1.16 |
if (!(clsd = closed)) { |
221 |
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for (BufferedSubscription<T> b = clients; b != null; b = next) { |
222 |
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next = b.next; |
223 |
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if (b.ctl < 0) { // disabled; remove |
224 |
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if (pred == null) |
225 |
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clients = next; |
226 |
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else |
227 |
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pred.next = next; |
228 |
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} |
229 |
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else if (subscriber == b.subscriber) { |
230 |
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present = true; |
231 |
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break; |
232 |
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} |
233 |
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pred = b; |
234 |
dl |
1.1 |
} |
235 |
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} |
236 |
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if (!present) { |
237 |
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subscriber.onSubscribe(sub); // don't link on exception |
238 |
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if (!clsd) { |
239 |
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if (pred == null) |
240 |
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clients = sub; |
241 |
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else |
242 |
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pred.next = sub; |
243 |
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} |
244 |
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} |
245 |
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} |
246 |
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if (clsd) |
247 |
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subscriber.onComplete(); |
248 |
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else if (present) |
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subscriber.onError(new IllegalStateException("Already subscribed")); |
250 |
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} |
251 |
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252 |
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/** |
253 |
dl |
1.16 |
* Publishes the given item to each current subscriber by |
254 |
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* asynchronously invoking its onNext method, blocking |
255 |
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* uninterruptibly while resources for any subscriber are |
256 |
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* unavailable. |
257 |
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* |
258 |
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* <p>If the Executor for this publisher throws a |
259 |
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* RejectedExecutionException (or any other RuntimeException or |
260 |
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* Error) when attempting to asynchronously notify subscribers, |
261 |
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* then this exception is rethrown. |
262 |
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* |
263 |
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* @param item the (non-null) item to publish |
264 |
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* @throws IllegalStateException if closed |
265 |
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* @throws NullPointerException if item is null |
266 |
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* @throws RejectedExecutionException if thrown by Executor |
267 |
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*/ |
268 |
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public void submit(T item) { |
269 |
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if (item == null) throw new NullPointerException(); |
270 |
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synchronized (this) { |
271 |
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if (closed) |
272 |
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throw new IllegalStateException("Closed"); |
273 |
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BufferedSubscription<T> pred = null, next; |
274 |
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for (BufferedSubscription<T> b = clients; b != null; b = next) { |
275 |
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int stat; |
276 |
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next = b.next; |
277 |
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if ((stat = b.submit(item)) < 0) { |
278 |
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if (pred == null) |
279 |
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clients = next; |
280 |
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else |
281 |
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pred.next = next; |
282 |
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} |
283 |
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else |
284 |
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pred = b; |
285 |
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} |
286 |
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} |
287 |
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} |
288 |
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289 |
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/** |
290 |
dl |
1.1 |
* Publishes the given item, if possible, to each current |
291 |
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* subscriber by asynchronously invoking its onNext method. The |
292 |
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* item may be dropped by one or more subscribers if resource |
293 |
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* limits are exceeded, in which case the given handler (if |
294 |
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* non-null) is invoked, and if it returns true, retried once. |
295 |
dl |
1.16 |
* Other calls to methods in this class by other threads are |
296 |
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* blocked while the handler is invoked. Unless recovery is |
297 |
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* assured, options are usually limited to logging the error |
298 |
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* and/or issuing an onError signal to the subscriber. |
299 |
dl |
1.1 |
* |
300 |
|
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* <p>If the Executor for this publisher throws a |
301 |
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* RejectedExecutionException (or any other RuntimeException or |
302 |
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* Error) when attempting to asynchronously notify subscribers, or |
303 |
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* the drop handler throws an exception when processing a dropped |
304 |
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* item, then this exception is rethrown. |
305 |
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* |
306 |
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* @param item the (non-null) item to publish |
307 |
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* @param onDrop if non-null, the handler invoked upon a drop to a |
308 |
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* subscriber, with arguments of the subscriber and item; if it |
309 |
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* returns true, an offer is re-attempted (once) |
310 |
jsr166 |
1.4 |
* @return the number of drops (failed attempts to issue the item |
311 |
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* to a subscriber) |
312 |
dl |
1.1 |
* @throws IllegalStateException if closed |
313 |
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* @throws NullPointerException if item is null |
314 |
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* @throws RejectedExecutionException if thrown by Executor |
315 |
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*/ |
316 |
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public int offer(T item, |
317 |
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BiPredicate<Flow.Subscriber<? super T>, ? super T> onDrop) { |
318 |
|
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if (item == null) throw new NullPointerException(); |
319 |
|
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int drops = 0; |
320 |
jsr166 |
1.2 |
synchronized (this) { |
321 |
dl |
1.1 |
if (closed) |
322 |
|
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throw new IllegalStateException("Closed"); |
323 |
|
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BufferedSubscription<T> pred = null, next; |
324 |
|
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for (BufferedSubscription<T> b = clients; b != null; b = next) { |
325 |
|
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int stat; |
326 |
|
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next = b.next; |
327 |
|
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if ((stat = b.offer(item)) == 0 && |
328 |
|
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onDrop != null && |
329 |
|
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onDrop.test(b.subscriber, item)) |
330 |
|
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stat = b.offer(item); |
331 |
|
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if (stat < 0) { |
332 |
|
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if (pred == null) |
333 |
|
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clients = next; |
334 |
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else |
335 |
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pred.next = next; |
336 |
|
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} |
337 |
|
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else { |
338 |
|
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pred = b; |
339 |
|
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if (stat == 0) |
340 |
|
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++drops; |
341 |
|
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} |
342 |
|
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} |
343 |
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return drops; |
344 |
|
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} |
345 |
|
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} |
346 |
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|
347 |
|
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/** |
348 |
|
|
* Publishes the given item, if possible, to each current |
349 |
|
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* subscriber by asynchronously invoking its onNext method, |
350 |
|
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* blocking while resources for any subscription are unavailable, |
351 |
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* up to the specified timeout or the caller thread is |
352 |
dl |
1.16 |
* interrupted, at which point the given handler (if non-null) is |
353 |
|
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* invoked, and if it returns true, retried once. (The drop |
354 |
|
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* handler may distinguish timeouts from interrupts by checking |
355 |
|
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* whether the current thread is interrupted.) Other calls to |
356 |
|
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* methods in this class by other threads are blocked while the |
357 |
|
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* handler is invoked. Unless recovery is assured, options are |
358 |
|
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* usually limited to logging the error and/or issuing an onError |
359 |
|
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* signal to the subscriber. |
360 |
dl |
1.1 |
* |
361 |
|
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* <p>If the Executor for this publisher throws a |
362 |
|
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* RejectedExecutionException (or any other RuntimeException or |
363 |
|
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* Error) when attempting to asynchronously notify subscribers, or |
364 |
|
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* the drop handler throws an exception when processing a dropped |
365 |
|
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* item, then this exception is rethrown. |
366 |
|
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* |
367 |
|
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* @param item the (non-null) item to publish |
368 |
|
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* @param timeout how long to wait for resources for any subscriber |
369 |
|
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* before giving up, in units of {@code unit} |
370 |
|
|
* @param unit a {@code TimeUnit} determining how to interpret the |
371 |
|
|
* {@code timeout} parameter |
372 |
|
|
* @param onDrop if non-null, the handler invoked upon a drop to a |
373 |
|
|
* subscriber, with arguments of the subscriber and item; if it |
374 |
|
|
* returns true, an offer is re-attempted (once) |
375 |
jsr166 |
1.4 |
* @return the number of drops (failed attempts to issue the item |
376 |
|
|
* to a subscriber) |
377 |
dl |
1.1 |
* @throws IllegalStateException if closed |
378 |
|
|
* @throws NullPointerException if item is null |
379 |
|
|
* @throws RejectedExecutionException if thrown by Executor |
380 |
|
|
*/ |
381 |
|
|
public int offer(T item, long timeout, TimeUnit unit, |
382 |
|
|
BiPredicate<Flow.Subscriber<? super T>, ? super T> onDrop) { |
383 |
|
|
if (item == null) throw new NullPointerException(); |
384 |
|
|
long nanos = unit.toNanos(timeout); |
385 |
|
|
int drops = 0; |
386 |
jsr166 |
1.2 |
synchronized (this) { |
387 |
dl |
1.1 |
if (closed) |
388 |
|
|
throw new IllegalStateException("Closed"); |
389 |
|
|
BufferedSubscription<T> pred = null, next; |
390 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
391 |
|
|
int stat; |
392 |
|
|
next = b.next; |
393 |
dl |
1.16 |
if ((stat = b.timedOffer(item, nanos)) == 0 && |
394 |
|
|
onDrop != null && onDrop.test(b.subscriber, item)) |
395 |
dl |
1.1 |
stat = b.offer(item); |
396 |
|
|
if (stat < 0) { |
397 |
|
|
if (pred == null) |
398 |
|
|
clients = next; |
399 |
|
|
else |
400 |
|
|
pred.next = next; |
401 |
|
|
} |
402 |
|
|
else { |
403 |
|
|
pred = b; |
404 |
|
|
if (stat == 0) |
405 |
|
|
++drops; |
406 |
|
|
} |
407 |
|
|
} |
408 |
|
|
} |
409 |
|
|
return drops; |
410 |
|
|
} |
411 |
|
|
|
412 |
|
|
/** |
413 |
|
|
* Unless already closed, issues onComplete signals to current |
414 |
|
|
* subscribers, and disallows subsequent attempts to publish. |
415 |
|
|
*/ |
416 |
|
|
public void close() { |
417 |
|
|
if (!closed) { |
418 |
|
|
BufferedSubscription<T> b, next; |
419 |
jsr166 |
1.2 |
synchronized (this) { |
420 |
dl |
1.1 |
b = clients; |
421 |
|
|
clients = null; |
422 |
|
|
closed = true; |
423 |
|
|
} |
424 |
|
|
while (b != null) { |
425 |
|
|
next = b.next; |
426 |
|
|
b.close(); |
427 |
|
|
b = next; |
428 |
|
|
} |
429 |
|
|
} |
430 |
|
|
} |
431 |
|
|
|
432 |
|
|
/** |
433 |
|
|
* Unless already closed, issues onError signals to current |
434 |
|
|
* subscribers with the given error, and disallows subsequent |
435 |
|
|
* attempts to publish. |
436 |
|
|
* |
437 |
jsr166 |
1.5 |
* @param error the onError argument sent to subscribers |
438 |
dl |
1.1 |
* @throws NullPointerException if error is null |
439 |
|
|
*/ |
440 |
|
|
public void closeExceptionally(Throwable error) { |
441 |
|
|
if (error == null) |
442 |
|
|
throw new NullPointerException(); |
443 |
|
|
if (!closed) { |
444 |
|
|
BufferedSubscription<T> b, next; |
445 |
jsr166 |
1.2 |
synchronized (this) { |
446 |
dl |
1.1 |
b = clients; |
447 |
|
|
clients = null; |
448 |
|
|
closed = true; |
449 |
|
|
} |
450 |
|
|
while (b != null) { |
451 |
|
|
next = b.next; |
452 |
|
|
b.closeExceptionally(error); |
453 |
|
|
b = next; |
454 |
|
|
} |
455 |
|
|
} |
456 |
|
|
} |
457 |
|
|
|
458 |
|
|
/** |
459 |
|
|
* Returns true if this publisher is not accepting submissions. |
460 |
|
|
* |
461 |
|
|
* @return true if closed |
462 |
|
|
*/ |
463 |
|
|
public boolean isClosed() { |
464 |
|
|
return closed; |
465 |
|
|
} |
466 |
|
|
|
467 |
|
|
/** |
468 |
jsr166 |
1.6 |
* Returns true if this publisher has any subscribers. |
469 |
dl |
1.1 |
* |
470 |
|
|
* @return true if this publisher has any subscribers |
471 |
|
|
*/ |
472 |
|
|
public boolean hasSubscribers() { |
473 |
|
|
boolean nonEmpty = false; |
474 |
|
|
if (!closed) { |
475 |
jsr166 |
1.2 |
synchronized (this) { |
476 |
dl |
1.1 |
BufferedSubscription<T> pred = null, next; |
477 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
478 |
|
|
next = b.next; |
479 |
|
|
if (b.ctl < 0) { |
480 |
|
|
if (pred == null) |
481 |
|
|
clients = next; |
482 |
|
|
else |
483 |
|
|
pred.next = next; |
484 |
jsr166 |
1.2 |
} |
485 |
dl |
1.1 |
else { |
486 |
|
|
nonEmpty = true; |
487 |
|
|
break; |
488 |
|
|
} |
489 |
|
|
} |
490 |
|
|
} |
491 |
|
|
} |
492 |
|
|
return nonEmpty; |
493 |
|
|
} |
494 |
|
|
|
495 |
|
|
/** |
496 |
|
|
* Returns the Executor used for asynchronous delivery. |
497 |
|
|
* |
498 |
|
|
* @return the Executor used for asynchronous delivery |
499 |
|
|
*/ |
500 |
|
|
public Executor getExecutor() { |
501 |
|
|
return executor; |
502 |
|
|
} |
503 |
|
|
|
504 |
jsr166 |
1.7 |
/** |
505 |
jsr166 |
1.5 |
* Returns the initial per-subscriber buffer capacity. |
506 |
dl |
1.1 |
* |
507 |
jsr166 |
1.5 |
* @return the initial per-subscriber buffer capacity |
508 |
dl |
1.1 |
*/ |
509 |
|
|
public int getInitialBufferCapacity() { |
510 |
|
|
return minBufferCapacity; |
511 |
|
|
} |
512 |
|
|
|
513 |
jsr166 |
1.7 |
/** |
514 |
jsr166 |
1.5 |
* Returns the maximum per-subscriber buffer capacity. |
515 |
dl |
1.1 |
* |
516 |
jsr166 |
1.5 |
* @return the maximum per-subscriber buffer capacity |
517 |
dl |
1.1 |
*/ |
518 |
|
|
public int getMaxBufferCapacity() { |
519 |
|
|
return maxBufferCapacity; |
520 |
|
|
} |
521 |
|
|
|
522 |
|
|
/** |
523 |
|
|
* Returns a list of current subscribers. |
524 |
|
|
* |
525 |
|
|
* @return list of current subscribers |
526 |
|
|
*/ |
527 |
|
|
public List<Flow.Subscriber<? super T>> getSubscribers() { |
528 |
|
|
ArrayList<Flow.Subscriber<? super T>> subs = new ArrayList<>(); |
529 |
jsr166 |
1.2 |
synchronized (this) { |
530 |
dl |
1.1 |
BufferedSubscription<T> pred = null, next; |
531 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
532 |
|
|
next = b.next; |
533 |
|
|
if (b.ctl < 0) { |
534 |
|
|
if (pred == null) |
535 |
|
|
clients = next; |
536 |
|
|
else |
537 |
|
|
pred.next = next; |
538 |
jsr166 |
1.2 |
} |
539 |
dl |
1.1 |
else |
540 |
|
|
subs.add(b.subscriber); |
541 |
|
|
} |
542 |
|
|
} |
543 |
|
|
return subs; |
544 |
|
|
} |
545 |
jsr166 |
1.2 |
|
546 |
dl |
1.1 |
/** |
547 |
|
|
* Returns true if the given Subscriber is currently subscribed. |
548 |
|
|
* |
549 |
|
|
* @param subscriber the subscriber |
550 |
|
|
* @return true if currently subscribed |
551 |
|
|
*/ |
552 |
|
|
public boolean isSubscribed(Flow.Subscriber<? super T> subscriber) { |
553 |
jsr166 |
1.2 |
if (!closed) { |
554 |
|
|
synchronized (this) { |
555 |
dl |
1.1 |
BufferedSubscription<T> pred = null, next; |
556 |
|
|
for (BufferedSubscription<T> b = clients; b != null; b = next) { |
557 |
|
|
next = b.next; |
558 |
|
|
if (b.ctl < 0) { |
559 |
|
|
if (pred == null) |
560 |
|
|
clients = next; |
561 |
|
|
else |
562 |
|
|
pred.next = next; |
563 |
jsr166 |
1.2 |
} |
564 |
dl |
1.1 |
else if (subscriber == b.subscriber) |
565 |
|
|
return true; |
566 |
|
|
} |
567 |
|
|
} |
568 |
|
|
} |
569 |
|
|
return false; |
570 |
|
|
} |
571 |
|
|
|
572 |
|
|
/** |
573 |
|
|
* If the given subscription is managed by a SubmissionPublisher, |
574 |
|
|
* returns an estimate of the number of items produced but not yet |
575 |
|
|
* consumed; otherwise returns zero. This method is designed only |
576 |
|
|
* for monitoring purposes, not for control. |
577 |
|
|
* |
578 |
|
|
* @param subscription the subscription |
579 |
|
|
* @return the estimate, or zero if the subscription is of an |
580 |
jsr166 |
1.8 |
* unknown type |
581 |
dl |
1.1 |
*/ |
582 |
|
|
public static int estimateAvailable(Flow.Subscription subscription) { |
583 |
|
|
if (subscription instanceof BufferedSubscription) |
584 |
|
|
return ((BufferedSubscription)subscription).estimateAvailable(); |
585 |
|
|
else |
586 |
|
|
return 0; |
587 |
|
|
} |
588 |
|
|
|
589 |
|
|
/** |
590 |
dl |
1.15 |
* A bounded (ring) buffer with integrated control to start a |
591 |
|
|
* consumer task whenever items are available. The buffer |
592 |
dl |
1.1 |
* algorithm is similar to one used inside ForkJoinPool, |
593 |
|
|
* specialized for the case of at most one concurrent producer and |
594 |
|
|
* consumer, and power of two buffer sizes. This allows methods to |
595 |
|
|
* operate without locks even while supporting resizing, blocking, |
596 |
|
|
* task-triggering, and garbage-free buffers (nulling out elements |
597 |
|
|
* when consumed), although supporting these does impose a bit of |
598 |
|
|
* overhead compared to plain fixed-size ring buffers. |
599 |
|
|
* |
600 |
|
|
* The publisher guarantees a single producer via its lock. We |
601 |
|
|
* ensure in this class that there is at most one consumer. The |
602 |
|
|
* request and cancel methods must be fully thread-safe but are |
603 |
|
|
* coded to exploit the most common case in which they are only |
604 |
|
|
* called by consumers (usually within onNext). |
605 |
|
|
* |
606 |
dl |
1.15 |
* This class also serves as its own consumer task, consuming as |
607 |
|
|
* many items/signals as possible before terminating, at which |
608 |
|
|
* point it is re-executed created when needed. (The dual Runnable |
609 |
|
|
* and ForkJoinTask declaration saves overhead when executed by |
610 |
|
|
* ForkJoinPools, without impacting other kinds of Executors.) |
611 |
|
|
* Execution control is managed using the ACTIVE ctl bit. We |
612 |
|
|
* ensure that a task is active when consumable items (and |
613 |
|
|
* usually, ERROR or COMPLETE signals) are present and there is |
614 |
|
|
* demand (unfulfilled requests). This is complicated on the |
615 |
dl |
1.1 |
* creation side by the possibility of exceptions when trying to |
616 |
|
|
* execute tasks. These eventually force DISABLED state, but |
617 |
|
|
* sometimes not directly. On the task side, termination (clearing |
618 |
|
|
* ACTIVE) may race with producers or request() calls, so in some |
619 |
|
|
* cases requires a re-check, re-activating if possible. |
620 |
|
|
* |
621 |
|
|
* The ctl field also manages run state. When DISABLED, no further |
622 |
|
|
* updates are possible (to simplify checks, DISABLED is defined |
623 |
|
|
* as a negative value). Disabling may be preceded by setting |
624 |
|
|
* ERROR or COMPLETE (or both -- ERROR has precedence), in which |
625 |
|
|
* case the associated Subscriber methods are invoked, possibly |
626 |
|
|
* synchronously if there is no active consumer task (including |
627 |
|
|
* cases where execute() failed). |
628 |
|
|
* |
629 |
|
|
* Support for blocking also exploits the fact that there is only |
630 |
|
|
* one possible waiter. ManagedBlocker-compatible control fields |
631 |
|
|
* are placed in this class itself rather than in wait-nodes. |
632 |
|
|
* Blocking control relies on the "waiter" field. Producers set |
633 |
|
|
* the field before trying to block, but must then recheck (via |
634 |
|
|
* offer) before parking. Signalling then just unparks and clears |
635 |
|
|
* waiter field. |
636 |
|
|
* |
637 |
|
|
* This class uses @Contended and heuristic field declaration |
638 |
|
|
* ordering to reduce memory contention on BufferedSubscription |
639 |
|
|
* itself, but it does not currently attempt to avoid memory |
640 |
|
|
* contention (especially including card-marks) among buffer |
641 |
|
|
* elements, that can significantly slow down some usages. |
642 |
|
|
* Addressing this may require allocating substantially more space |
643 |
|
|
* than users expect. |
644 |
|
|
*/ |
645 |
dl |
1.15 |
@SuppressWarnings("serial") |
646 |
dl |
1.1 |
@sun.misc.Contended |
647 |
dl |
1.15 |
static final class BufferedSubscription<T> extends ForkJoinTask<Void> |
648 |
|
|
implements Runnable, Flow.Subscription, ForkJoinPool.ManagedBlocker { |
649 |
dl |
1.1 |
// Order-sensitive field declarations |
650 |
|
|
long timeout; // > 0 if timed wait |
651 |
|
|
volatile long demand; // # unfilled requests |
652 |
|
|
final int minCapacity; // initial buffer size |
653 |
|
|
int maxCapacity; // reduced on OOME |
654 |
|
|
int putStat; // offer result for ManagedBlocker |
655 |
|
|
volatile int ctl; // atomic run state flags |
656 |
|
|
volatile int head; // next position to take |
657 |
|
|
volatile int tail; // next position to put |
658 |
|
|
volatile Object[] array; // buffer: null if disabled |
659 |
|
|
Flow.Subscriber<? super T> subscriber; // null if disabled |
660 |
|
|
Executor executor; // null if disabled |
661 |
|
|
volatile Throwable pendingError; // holds until onError issued |
662 |
|
|
volatile Thread waiter; // blocked producer thread |
663 |
|
|
T putItem; // for offer within ManagedBlocker |
664 |
|
|
BufferedSubscription<T> next; // used only by publisher |
665 |
|
|
|
666 |
|
|
// ctl values |
667 |
|
|
static final int ACTIVE = 0x01; // consumer task active |
668 |
|
|
static final int ERROR = 0x02; // signal pending error |
669 |
|
|
static final int COMPLETE = 0x04; // signal completion when done |
670 |
|
|
static final int DISABLED = 0x80000000; // must be negative |
671 |
|
|
|
672 |
dl |
1.16 |
static final long INTERRUPTED = -1L; // timeout vs interrupt sentinel |
673 |
|
|
|
674 |
dl |
1.1 |
BufferedSubscription(Flow.Subscriber<? super T> subscriber, |
675 |
|
|
Executor executor, int minBufferCapacity, |
676 |
|
|
int maxBufferCapacity) { |
677 |
|
|
this.subscriber = subscriber; |
678 |
|
|
this.executor = executor; |
679 |
|
|
this.minCapacity = minBufferCapacity; |
680 |
|
|
this.maxCapacity = maxBufferCapacity; |
681 |
|
|
} |
682 |
|
|
|
683 |
|
|
/** |
684 |
dl |
1.16 |
* Tries to add item and start consumer task if necessary. |
685 |
dl |
1.1 |
* @return -1 if disabled, 0 if dropped, else 1 |
686 |
|
|
*/ |
687 |
|
|
final int offer(T item) { |
688 |
|
|
Object[] a = array; |
689 |
dl |
1.16 |
int t = tail, h = head, n, i, stat; |
690 |
|
|
if (a != null && (n = a.length) > t - h && (i = t & (n - 1)) >= 0) { |
691 |
|
|
a[i] = item; |
692 |
dl |
1.1 |
U.putOrderedInt(this, TAIL, t + 1); |
693 |
|
|
} |
694 |
dl |
1.16 |
else if ((stat = growAndAdd(a, item)) <= 0) |
695 |
|
|
return stat; |
696 |
|
|
for (int c;;) { // possibly start task |
697 |
|
|
Executor e; |
698 |
|
|
if (((c = ctl) & ACTIVE) != 0) |
699 |
|
|
break; |
700 |
|
|
else if (c < 0 || (e = executor) == null) |
701 |
|
|
return -1; |
702 |
|
|
else if (demand == 0L || tail == head) |
703 |
|
|
break; |
704 |
|
|
else if (U.compareAndSwapInt(this, CTL, c, c | ACTIVE)) { |
705 |
|
|
try { |
706 |
|
|
e.execute(this); |
707 |
|
|
break; |
708 |
|
|
} catch (RuntimeException | Error ex) { // back out |
709 |
|
|
do {} while ((c = ctl) >= 0 && |
710 |
|
|
(c & ACTIVE) != 0 && |
711 |
|
|
!U.compareAndSwapInt(this, CTL, c, |
712 |
|
|
c & ~ACTIVE)); |
713 |
|
|
throw ex; |
714 |
|
|
} |
715 |
|
|
} |
716 |
|
|
} |
717 |
|
|
return 1; |
718 |
dl |
1.1 |
} |
719 |
|
|
|
720 |
|
|
/** |
721 |
dl |
1.16 |
* Tries to create or expand buffer, then adds item if possible |
722 |
dl |
1.1 |
*/ |
723 |
dl |
1.16 |
final int growAndAdd(Object[] oldArray, T item) { |
724 |
|
|
int oldLen, newLen; |
725 |
|
|
if (oldArray != null) |
726 |
|
|
newLen = (oldLen = oldArray.length) << 1; |
727 |
|
|
else if (ctl >= 0) { |
728 |
dl |
1.1 |
oldLen = 0; |
729 |
dl |
1.16 |
newLen = minCapacity; |
730 |
dl |
1.1 |
} |
731 |
dl |
1.16 |
else |
732 |
|
|
return -1; // disabled |
733 |
|
|
if (oldLen >= maxCapacity || newLen <= 0) |
734 |
|
|
return 0; // cannot grow |
735 |
|
|
Object[] newArray; |
736 |
dl |
1.1 |
try { |
737 |
dl |
1.16 |
newArray = new Object[newLen]; |
738 |
|
|
} catch (Throwable ex) { // try to cope with OOME |
739 |
|
|
if (oldLen > 0) // avoid continuous failure |
740 |
dl |
1.1 |
maxCapacity = oldLen; |
741 |
|
|
return 0; |
742 |
|
|
} |
743 |
dl |
1.16 |
array = newArray; |
744 |
|
|
int t = tail, oldMask = oldLen - 1, newMask = newLen - 1; |
745 |
|
|
if (oldArray != null && oldMask >= 0 && newMask >= oldMask) { |
746 |
|
|
for (int j = head; j != t; ++j) { // races with consumer |
747 |
|
|
Object x; |
748 |
dl |
1.1 |
int i = j & oldMask; |
749 |
dl |
1.16 |
if ((x = oldArray[i]) != null && |
750 |
|
|
U.compareAndSwapObject(oldArray, |
751 |
dl |
1.1 |
(((long)i) << ASHIFT) + ABASE, |
752 |
|
|
x, null)) |
753 |
dl |
1.16 |
newArray[j & newMask] = x; |
754 |
dl |
1.1 |
} |
755 |
|
|
} |
756 |
dl |
1.16 |
newArray[t & newMask] = item; |
757 |
|
|
tail = t + 1; |
758 |
|
|
return 1; |
759 |
dl |
1.1 |
} |
760 |
|
|
|
761 |
|
|
/** |
762 |
dl |
1.16 |
* Nulls out most fields, mainly to avoid garbage retention |
763 |
|
|
* until publisher unsubscribes. |
764 |
dl |
1.1 |
*/ |
765 |
dl |
1.16 |
final void detach() { |
766 |
|
|
pendingError = null; |
767 |
|
|
subscriber = null; |
768 |
|
|
executor = null; |
769 |
|
|
array = null; |
770 |
|
|
Thread w = waiter; |
771 |
|
|
if (w != null) { |
772 |
|
|
waiter = null; |
773 |
|
|
LockSupport.unpark(w); // force wakeup |
774 |
dl |
1.1 |
} |
775 |
|
|
} |
776 |
|
|
|
777 |
|
|
/** |
778 |
|
|
* Tries to start consumer task upon a signal or request; |
779 |
jsr166 |
1.12 |
* disables on failure. |
780 |
dl |
1.1 |
*/ |
781 |
|
|
final void startOrDisable() { |
782 |
|
|
Executor e; // skip if already disabled |
783 |
|
|
if ((e = executor) != null) { |
784 |
|
|
try { |
785 |
dl |
1.15 |
e.execute(this); |
786 |
jsr166 |
1.2 |
} catch (Throwable ex) { // back out and force signal |
787 |
dl |
1.1 |
for (int c;;) { |
788 |
|
|
if ((c = ctl) < 0 || (c & ACTIVE) == 0) |
789 |
|
|
break; |
790 |
|
|
if (U.compareAndSwapInt(this, CTL, c, c & ~ACTIVE)) { |
791 |
|
|
closeExceptionally(ex); |
792 |
|
|
break; |
793 |
|
|
} |
794 |
|
|
} |
795 |
|
|
} |
796 |
|
|
} |
797 |
|
|
} |
798 |
|
|
|
799 |
dl |
1.16 |
final void close() { |
800 |
dl |
1.1 |
for (int c;;) { |
801 |
|
|
if ((c = ctl) < 0) |
802 |
|
|
break; |
803 |
dl |
1.16 |
if (U.compareAndSwapInt(this, CTL, c, c | (ACTIVE | COMPLETE))) { |
804 |
|
|
if ((c & ACTIVE) == 0) |
805 |
|
|
startOrDisable(); |
806 |
dl |
1.1 |
break; |
807 |
|
|
} |
808 |
|
|
} |
809 |
|
|
} |
810 |
|
|
|
811 |
|
|
final void closeExceptionally(Throwable ex) { |
812 |
|
|
for (int c;;) { |
813 |
|
|
if ((c = ctl) < 0) |
814 |
|
|
break; |
815 |
|
|
else if ((c & ACTIVE) != 0) { |
816 |
dl |
1.16 |
pendingError = ex; |
817 |
dl |
1.1 |
if (U.compareAndSwapInt(this, CTL, c, c | ERROR)) |
818 |
|
|
break; // cause consumer task to exit |
819 |
|
|
} |
820 |
|
|
else if (U.compareAndSwapInt(this, CTL, c, DISABLED)) { |
821 |
|
|
Flow.Subscriber<? super T> s = subscriber; |
822 |
dl |
1.16 |
if (s != null && ex != null) { |
823 |
dl |
1.1 |
try { |
824 |
|
|
s.onError(ex); |
825 |
jsr166 |
1.2 |
} catch (Throwable ignore) { |
826 |
dl |
1.1 |
} |
827 |
|
|
} |
828 |
|
|
detach(); |
829 |
|
|
break; |
830 |
|
|
} |
831 |
|
|
} |
832 |
|
|
} |
833 |
|
|
|
834 |
dl |
1.16 |
/** |
835 |
|
|
* Causes consumer task to exit if active (without reporting |
836 |
|
|
* onError unless there is already a pending error), and |
837 |
|
|
* disables. |
838 |
|
|
*/ |
839 |
|
|
public void cancel() { |
840 |
dl |
1.1 |
for (int c;;) { |
841 |
|
|
if ((c = ctl) < 0) |
842 |
|
|
break; |
843 |
dl |
1.16 |
else if ((c & ACTIVE) != 0) { |
844 |
|
|
if (U.compareAndSwapInt(this, CTL, c, c | ERROR)) |
845 |
|
|
break; |
846 |
|
|
} |
847 |
|
|
else if (U.compareAndSwapInt(this, CTL, c, DISABLED)) { |
848 |
|
|
detach(); |
849 |
dl |
1.1 |
break; |
850 |
|
|
} |
851 |
|
|
} |
852 |
|
|
} |
853 |
|
|
|
854 |
dl |
1.16 |
/** |
855 |
|
|
* Adds to demand and possibly starts task. |
856 |
|
|
*/ |
857 |
|
|
public void request(long n) { |
858 |
|
|
if (n > 0L) { |
859 |
|
|
for (;;) { |
860 |
|
|
long prev = demand, d; |
861 |
|
|
if ((d = prev + n) < prev) // saturate |
862 |
|
|
d = Long.MAX_VALUE; |
863 |
|
|
if (U.compareAndSwapLong(this, DEMAND, prev, d)) { |
864 |
|
|
for (int c, h;;) { |
865 |
|
|
if (((c = ctl) & (ACTIVE | DISABLED)) != 0 || |
866 |
|
|
demand == 0L) |
867 |
|
|
break; |
868 |
|
|
if ((h = head) != tail) { |
869 |
|
|
if (U.compareAndSwapInt(this, CTL, c, |
870 |
|
|
c | ACTIVE)) { |
871 |
|
|
startOrDisable(); |
872 |
|
|
break; |
873 |
|
|
} |
874 |
|
|
} |
875 |
|
|
else if (head == h && tail == h) |
876 |
|
|
break; |
877 |
|
|
} |
878 |
|
|
break; |
879 |
|
|
} |
880 |
|
|
} |
881 |
|
|
} |
882 |
|
|
else if (n < 0L) |
883 |
|
|
closeExceptionally(new IllegalArgumentException( |
884 |
|
|
"negative subscription request")); |
885 |
|
|
} |
886 |
|
|
|
887 |
dl |
1.1 |
final int estimateAvailable() { |
888 |
|
|
int n; |
889 |
|
|
return (ctl >= 0 && (n = tail - head) > 0) ? n : 0; |
890 |
|
|
} |
891 |
|
|
|
892 |
|
|
// ManagedBlocker support |
893 |
|
|
|
894 |
|
|
public final boolean isReleasable() { |
895 |
|
|
T item = putItem; |
896 |
|
|
if (item != null) { |
897 |
|
|
if ((putStat = offer(item)) == 0) |
898 |
|
|
return false; |
899 |
|
|
putItem = null; |
900 |
|
|
} |
901 |
|
|
return true; |
902 |
|
|
} |
903 |
|
|
|
904 |
|
|
public final boolean block() { |
905 |
|
|
T item = putItem; |
906 |
|
|
if (item != null) { |
907 |
|
|
putItem = null; |
908 |
|
|
long nanos = timeout; |
909 |
|
|
long deadline = (nanos > 0L) ? System.nanoTime() + nanos : 0L; |
910 |
|
|
while ((putStat = offer(item)) == 0) { |
911 |
|
|
if (Thread.interrupted()) { |
912 |
dl |
1.16 |
timeout = INTERRUPTED; |
913 |
dl |
1.1 |
if (nanos > 0L) |
914 |
|
|
break; |
915 |
|
|
} |
916 |
|
|
else if (nanos > 0L && |
917 |
|
|
(nanos = deadline - System.nanoTime()) <= 0L) |
918 |
|
|
break; |
919 |
|
|
else if (waiter == null) |
920 |
|
|
waiter = Thread.currentThread(); |
921 |
|
|
else { |
922 |
|
|
if (nanos > 0L) |
923 |
|
|
LockSupport.parkNanos(this, nanos); |
924 |
|
|
else |
925 |
|
|
LockSupport.park(this); |
926 |
|
|
waiter = null; |
927 |
|
|
} |
928 |
|
|
} |
929 |
|
|
} |
930 |
|
|
waiter = null; |
931 |
|
|
return true; |
932 |
|
|
} |
933 |
|
|
|
934 |
|
|
final int submit(T item) { |
935 |
dl |
1.16 |
int stat; |
936 |
|
|
if ((stat = offer(item)) == 0) { |
937 |
|
|
putItem = item; |
938 |
|
|
timeout = 0L; |
939 |
|
|
try { |
940 |
|
|
ForkJoinPool.managedBlock(this); |
941 |
|
|
} catch (InterruptedException cantHappen) { |
942 |
|
|
} |
943 |
|
|
stat = putStat; |
944 |
|
|
if (timeout < 0L) |
945 |
|
|
Thread.currentThread().interrupt(); |
946 |
dl |
1.1 |
} |
947 |
dl |
1.16 |
return stat; |
948 |
dl |
1.1 |
} |
949 |
|
|
|
950 |
|
|
final int timedOffer(T item, long nanos) { |
951 |
dl |
1.16 |
int stat; |
952 |
|
|
if ((stat = offer(item)) == 0 && (timeout = nanos) > 0L) { |
953 |
|
|
putItem = item; |
954 |
|
|
try { |
955 |
|
|
ForkJoinPool.managedBlock(this); |
956 |
|
|
} catch (InterruptedException cantHappen) { |
957 |
|
|
} |
958 |
|
|
stat = putStat; |
959 |
|
|
if (timeout < 0L) |
960 |
|
|
Thread.currentThread().interrupt(); |
961 |
dl |
1.1 |
} |
962 |
dl |
1.16 |
return stat; |
963 |
dl |
1.1 |
} |
964 |
|
|
|
965 |
dl |
1.16 |
/** |
966 |
|
|
* Consumer task loop; supports resubmission when used as |
967 |
|
|
* ForkJoinTask. |
968 |
|
|
*/ |
969 |
|
|
public final boolean exec() { |
970 |
dl |
1.1 |
Flow.Subscriber<? super T> s; |
971 |
|
|
if ((s = subscriber) != null) { // else disabled |
972 |
|
|
for (;;) { |
973 |
|
|
long d = demand; // read volatile fields in acceptable order |
974 |
|
|
int c = ctl; |
975 |
|
|
int h = head; |
976 |
|
|
int t = tail; |
977 |
|
|
Object[] a = array; |
978 |
|
|
int i, n; Object x; Thread w; |
979 |
|
|
if (c < 0) { |
980 |
|
|
detach(); |
981 |
|
|
break; |
982 |
|
|
} |
983 |
|
|
else if ((c & ERROR) != 0) { |
984 |
|
|
Throwable ex = pendingError; |
985 |
|
|
ctl = DISABLED; // no need for CAS |
986 |
|
|
if (ex != null) { |
987 |
|
|
try { |
988 |
|
|
s.onError(ex); |
989 |
jsr166 |
1.2 |
} catch (Throwable ignore) { |
990 |
dl |
1.1 |
} |
991 |
|
|
} |
992 |
|
|
} |
993 |
|
|
else if (h == t) { // empty |
994 |
|
|
if (h == tail && |
995 |
|
|
U.compareAndSwapInt(this, CTL, c, c &= ~ACTIVE)) { |
996 |
|
|
if (h != tail || c != (c = ctl)) { // recheck |
997 |
|
|
if ((c & (ACTIVE | DISABLED)) != 0 || |
998 |
|
|
!U.compareAndSwapInt(this, CTL, c, |
999 |
|
|
c | ACTIVE)) |
1000 |
|
|
break; |
1001 |
|
|
} |
1002 |
|
|
else if ((c & COMPLETE) != 0) { |
1003 |
|
|
ctl = DISABLED; |
1004 |
|
|
try { |
1005 |
|
|
s.onComplete(); |
1006 |
jsr166 |
1.2 |
} catch (Throwable ignore) { |
1007 |
dl |
1.1 |
} |
1008 |
|
|
} |
1009 |
|
|
else |
1010 |
|
|
break; |
1011 |
|
|
} |
1012 |
|
|
} |
1013 |
dl |
1.16 |
else if (a == null || (n = a.length) == 0 || |
1014 |
|
|
(x = a[i = h & (n - 1)]) == null) |
1015 |
|
|
; // stale; retry |
1016 |
dl |
1.1 |
else if (d == 0L) { // can't take |
1017 |
|
|
if (demand == 0L && |
1018 |
|
|
U.compareAndSwapInt(this, CTL, c, c &= ~ACTIVE) && |
1019 |
|
|
((demand == 0L && c == (c = ctl)) || // recheck |
1020 |
|
|
(c & (ACTIVE | DISABLED)) != 0 || |
1021 |
|
|
!U.compareAndSwapInt(this, CTL, c, c | ACTIVE))) |
1022 |
|
|
break; |
1023 |
|
|
} |
1024 |
dl |
1.16 |
else if (U.compareAndSwapObject( |
1025 |
dl |
1.1 |
a, (((long)i) << ASHIFT) + ABASE, x, null)) { |
1026 |
|
|
U.putOrderedInt(this, HEAD, h + 1); |
1027 |
|
|
while (!U.compareAndSwapLong(this, DEMAND, d, d - 1L)) |
1028 |
|
|
d = demand; // almost never fails |
1029 |
|
|
if ((w = waiter) != null) { |
1030 |
|
|
waiter = null; |
1031 |
|
|
LockSupport.unpark(w); // release producer |
1032 |
|
|
} |
1033 |
|
|
try { |
1034 |
|
|
@SuppressWarnings("unchecked") T y = (T) x; |
1035 |
|
|
s.onNext(y); |
1036 |
dl |
1.16 |
} catch (Throwable ex) { // disable on throw |
1037 |
dl |
1.1 |
ctl = DISABLED; |
1038 |
|
|
} |
1039 |
|
|
} |
1040 |
|
|
} |
1041 |
|
|
} |
1042 |
dl |
1.16 |
return false; // resubmittable; never joined |
1043 |
dl |
1.1 |
} |
1044 |
|
|
|
1045 |
dl |
1.16 |
public final void run() { exec(); } |
1046 |
dl |
1.15 |
public final Void getRawResult() { return null; } |
1047 |
|
|
public final void setRawResult(Void v) {} |
1048 |
|
|
|
1049 |
jsr166 |
1.9 |
// Unsafe mechanics |
1050 |
|
|
private static final sun.misc.Unsafe U = sun.misc.Unsafe.getUnsafe(); |
1051 |
dl |
1.1 |
private static final long CTL; |
1052 |
|
|
private static final long TAIL; |
1053 |
|
|
private static final long HEAD; |
1054 |
|
|
private static final long DEMAND; |
1055 |
|
|
private static final int ABASE; |
1056 |
|
|
private static final int ASHIFT; |
1057 |
|
|
|
1058 |
|
|
static { |
1059 |
|
|
try { |
1060 |
|
|
CTL = U.objectFieldOffset |
1061 |
jsr166 |
1.9 |
(BufferedSubscription.class.getDeclaredField("ctl")); |
1062 |
dl |
1.1 |
TAIL = U.objectFieldOffset |
1063 |
jsr166 |
1.9 |
(BufferedSubscription.class.getDeclaredField("tail")); |
1064 |
dl |
1.1 |
HEAD = U.objectFieldOffset |
1065 |
jsr166 |
1.9 |
(BufferedSubscription.class.getDeclaredField("head")); |
1066 |
dl |
1.1 |
DEMAND = U.objectFieldOffset |
1067 |
jsr166 |
1.9 |
(BufferedSubscription.class.getDeclaredField("demand")); |
1068 |
|
|
|
1069 |
|
|
ABASE = U.arrayBaseOffset(Object[].class); |
1070 |
|
|
int scale = U.arrayIndexScale(Object[].class); |
1071 |
dl |
1.1 |
if ((scale & (scale - 1)) != 0) |
1072 |
|
|
throw new Error("data type scale not a power of two"); |
1073 |
|
|
ASHIFT = 31 - Integer.numberOfLeadingZeros(scale); |
1074 |
jsr166 |
1.9 |
} catch (ReflectiveOperationException e) { |
1075 |
dl |
1.1 |
throw new Error(e); |
1076 |
|
|
} |
1077 |
|
|
} |
1078 |
|
|
} |
1079 |
|
|
} |