src/jdk.incubator.httpclient/share/classes/jdk/incubator/http/internal/BufferingSubscriber.java
--- a/src/jdk.incubator.httpclient/share/classes/jdk/incubator/http/internal/BufferingSubscriber.java Tue Feb 06 19:37:56 2018 +0000
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,315 +0,0 @@
-/*
- * Copyright (c) 2017, 2018, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation. Oracle designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Oracle in the LICENSE file that accompanied this code.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-package jdk.incubator.http.internal;
-
-import java.nio.ByteBuffer;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.ListIterator;
-import java.util.Objects;
-import java.util.concurrent.CompletionStage;
-import java.util.concurrent.Flow;
-import java.util.concurrent.atomic.AtomicBoolean;
-import jdk.incubator.http.HttpResponse.BodySubscriber;
-import jdk.incubator.http.internal.common.Demand;
-import jdk.incubator.http.internal.common.SequentialScheduler;
-import jdk.incubator.http.internal.common.Utils;
-
-/**
- * A buffering BodySubscriber. When subscribed, accumulates ( buffers ) a given
- * amount ( in bytes ) of a publisher's data before pushing it to a downstream
- * subscriber.
- */
-public class BufferingSubscriber<T> implements BodySubscriber<T>
-{
- /** The downstream consumer of the data. */
- private final BodySubscriber<T> downstreamSubscriber;
- /** The amount of data to be accumulate before pushing downstream. */
- private final int bufferSize;
-
- /** The subscription, created lazily. */
- private volatile Flow.Subscription subscription;
- /** The downstream subscription, created lazily. */
- private volatile DownstreamSubscription downstreamSubscription;
-
- /** Must be held when accessing the internal buffers. */
- private final Object buffersLock = new Object();
- /** The internal buffers holding the buffered data. */
- private ArrayList<ByteBuffer> internalBuffers;
- /** The actual accumulated remaining bytes in internalBuffers. */
- private int accumulatedBytes;
-
- /** Holds the Throwable from upstream's onError. */
- private volatile Throwable throwable;
-
- /** State of the buffering subscriber:
- * 1) [UNSUBSCRIBED] when initially created
- * 2) [ACTIVE] when subscribed and can receive data
- * 3) [ERROR | CANCELLED | COMPLETE] (terminal state)
- */
- static final int UNSUBSCRIBED = 0x01;
- static final int ACTIVE = 0x02;
- static final int ERROR = 0x04;
- static final int CANCELLED = 0x08;
- static final int COMPLETE = 0x10;
-
- private volatile int state;
-
- public BufferingSubscriber(BodySubscriber<T> downstreamSubscriber,
- int bufferSize) {
- this.downstreamSubscriber = Objects.requireNonNull(downstreamSubscriber);
- this.bufferSize = bufferSize;
- synchronized (buffersLock) {
- internalBuffers = new ArrayList<>();
- }
- state = UNSUBSCRIBED;
- }
-
- /** Returns the number of bytes remaining in the given buffers. */
- private static final long remaining(List<ByteBuffer> buffers) {
- return buffers.stream().mapToLong(ByteBuffer::remaining).sum();
- }
-
- /**
- * Tells whether, or not, there is at least a sufficient number of bytes
- * accumulated in the internal buffers. If the subscriber is COMPLETE, and
- * has some buffered data, then there is always enough ( to pass downstream ).
- */
- private final boolean hasEnoughAccumulatedBytes() {
- assert Thread.holdsLock(buffersLock);
- return accumulatedBytes >= bufferSize
- || (state == COMPLETE && accumulatedBytes > 0);
- }
-
- /**
- * Returns a new, unmodifiable, List<ByteBuffer> containing exactly the
- * amount of data as required before pushing downstream. The amount of data
- * may be less than required ( bufferSize ), in the case where the subscriber
- * is COMPLETE.
- */
- private List<ByteBuffer> fromInternalBuffers() {
- assert Thread.holdsLock(buffersLock);
- int leftToFill = bufferSize;
- int state = this.state;
- assert (state == ACTIVE || state == CANCELLED)
- ? accumulatedBytes >= leftToFill : true;
- List<ByteBuffer> dsts = new ArrayList<>();
-
- ListIterator<ByteBuffer> itr = internalBuffers.listIterator();
- while (itr.hasNext()) {
- ByteBuffer b = itr.next();
- if (b.remaining() <= leftToFill) {
- itr.remove();
- if (b.position() != 0)
- b = b.slice(); // ensure position = 0 when propagated
- dsts.add(b);
- leftToFill -= b.remaining();
- accumulatedBytes -= b.remaining();
- if (leftToFill == 0)
- break;
- } else {
- int prevLimit = b.limit();
- b.limit(b.position() + leftToFill);
- ByteBuffer slice = b.slice();
- dsts.add(slice);
- b.limit(prevLimit);
- b.position(b.position() + leftToFill);
- accumulatedBytes -= leftToFill;
- leftToFill = 0;
- break;
- }
- }
- assert (state == ACTIVE || state == CANCELLED)
- ? leftToFill == 0 : state == COMPLETE;
- assert (state == ACTIVE || state == CANCELLED)
- ? remaining(dsts) == bufferSize : state == COMPLETE;
- assert accumulatedBytes >= 0;
- assert dsts.stream().noneMatch(b -> b.position() != 0);
- return Collections.unmodifiableList(dsts);
- }
-
- /** Subscription that is passed to the downstream subscriber. */
- private class DownstreamSubscription implements Flow.Subscription {
- private final AtomicBoolean cancelled = new AtomicBoolean(); // false
- private final Demand demand = new Demand();
- private volatile boolean illegalArg;
-
- @Override
- public void request(long n) {
- if (cancelled.get() || illegalArg) {
- return;
- }
- if (n <= 0L) {
- // pass the "bad" value upstream so the Publisher can deal with
- // it appropriately, i.e. invoke onError
- illegalArg = true;
- subscription.request(n);
- return;
- }
-
- demand.increase(n);
-
- pushDemanded();
- }
-
- private final SequentialScheduler pushDemandedScheduler =
- new SequentialScheduler(new PushDemandedTask());
-
- void pushDemanded() {
- if (cancelled.get())
- return;
- pushDemandedScheduler.runOrSchedule();
- }
-
- class PushDemandedTask extends SequentialScheduler.CompleteRestartableTask {
- @Override
- public void run() {
- try {
- Throwable t = throwable;
- if (t != null) {
- pushDemandedScheduler.stop(); // stop the demand scheduler
- downstreamSubscriber.onError(t);
- return;
- }
-
- while (true) {
- List<ByteBuffer> item;
- synchronized (buffersLock) {
- if (cancelled.get())
- return;
- if (!hasEnoughAccumulatedBytes())
- break;
- if (!demand.tryDecrement())
- break;
- item = fromInternalBuffers();
- }
- assert item != null;
-
- downstreamSubscriber.onNext(item);
- }
- if (cancelled.get())
- return;
-
- // complete only if all data consumed
- boolean complete;
- synchronized (buffersLock) {
- complete = state == COMPLETE && internalBuffers.isEmpty();
- }
- if (complete) {
- assert internalBuffers.isEmpty();
- pushDemandedScheduler.stop(); // stop the demand scheduler
- downstreamSubscriber.onComplete();
- return;
- }
- } catch (Throwable t) {
- cancel(); // cancel if there is any error
- throw t;
- }
-
- boolean requestMore = false;
- synchronized (buffersLock) {
- if (!hasEnoughAccumulatedBytes() && !demand.isFulfilled()) {
- // request more upstream data
- requestMore = true;
- }
- }
- if (requestMore)
- subscription.request(1);
- }
- }
-
- @Override
- public void cancel() {
- if (cancelled.compareAndExchange(false, true))
- return; // already cancelled
-
- state = CANCELLED; // set CANCELLED state of upstream subscriber
- subscription.cancel(); // cancel upstream subscription
- pushDemandedScheduler.stop(); // stop the demand scheduler
- }
- }
-
- @Override
- public void onSubscribe(Flow.Subscription subscription) {
- Objects.requireNonNull(subscription);
- if (this.subscription != null) {
- subscription.cancel();
- return;
- }
-
- int s = this.state;
- assert s == UNSUBSCRIBED;
- state = ACTIVE;
- this.subscription = subscription;
- downstreamSubscription = new DownstreamSubscription();
- downstreamSubscriber.onSubscribe(downstreamSubscription);
- }
-
- @Override
- public void onNext(List<ByteBuffer> item) {
- Objects.requireNonNull(item);
-
- int s = state;
- if (s == CANCELLED)
- return;
-
- if (s != ACTIVE)
- throw new InternalError("onNext on inactive subscriber");
-
- synchronized (buffersLock) {
- internalBuffers.addAll(item);
- accumulatedBytes += remaining(item);
- }
-
- downstreamSubscription.pushDemanded();
- }
-
- @Override
- public void onError(Throwable incomingThrowable) {
- Objects.requireNonNull(incomingThrowable);
- int s = state;
- assert s == ACTIVE : "Expected ACTIVE, got:" + s;
- state = ERROR;
- Throwable t = this.throwable;
- assert t == null : "Expected null, got:" + t;
- this.throwable = incomingThrowable;
- downstreamSubscription.pushDemanded();
- }
-
- @Override
- public void onComplete() {
- int s = state;
- assert s == ACTIVE : "Expected ACTIVE, got:" + s;
- state = COMPLETE;
- downstreamSubscription.pushDemanded();
- }
-
- @Override
- public CompletionStage<T> getBody() {
- return downstreamSubscriber.getBody();
- }
-}