Add generic utility for enqueuing buffers with promises and dequeueing them in arbitrary byte ranges.
Motivation: Simplifies writing code that needs to merge or slice a sequence of buffer & promise pairs into chunks of arbitrary sizes. For example in HTTP2 we merge or split buffers across fixed-size DATA frame boundaries. Modifications: Add new utility class CoalescingBufferQueue Result: Following this change HTTP2 code will switch to use it instead of CompositeByteBuffer for DATA frame coalescing.
This commit is contained in:
Louis Ryan
nmittler
parent
8a16081a93
commit
319d745a13
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/*
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* Copyright 2015 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License, version 2.0 (the
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* "License"); you may not use this file except in compliance with the License. You may obtain a
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* copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under the License
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* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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* or implied. See the License for the specific language governing permissions and limitations under
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* the License.
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*/
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package io.netty.channel;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.CompositeByteBuf;
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import io.netty.buffer.Unpooled;
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import io.netty.util.ReferenceCountUtil;
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import io.netty.util.internal.ObjectUtil;
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import java.util.ArrayDeque;
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/**
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* A FIFO queue of bytes where producers add bytes by repeatedly adding {@link ByteBuf} and consumers take bytes in
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* arbitrary lengths. This allows producers to add lots of small buffers and the consumer to take all the bytes
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* out in a single buffer. Conversely the producer may add larger buffers and the consumer could take the bytes in
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* many small buffers.
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*
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* <p>Bytes are added and removed with promises. If the last byte of a buffer added with a promise is removed then
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* that promise will complete when the promise passed to {@link #remove} completes.
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*
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* <p>This functionality is useful for aggregating or partitioning writes into fixed size buffers for framing protocols
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* such as HTTP2.
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*/
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public final class CoalescingBufferQueue {
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private final Channel channel;
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private final ArrayDeque<Object> bufAndListenerPairs = new ArrayDeque<Object>();
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private int readableBytes;
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public CoalescingBufferQueue(Channel channel) {
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this.channel = ObjectUtil.checkNotNull(channel, "channel");
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}
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/**
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* Add a buffer to the end of the queue.
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*/
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public void add(ByteBuf buf) {
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add(buf, (ChannelFutureListener) null);
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}
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/**
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* Add a buffer to the end of the queue and associate a promise with it that should be completed when
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* all the buffers bytes have been consumed from the queue and written.
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* @param buf to add to the tail of the queue
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* @param promise to complete when all the bytes have been consumed and written, can be void.
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*/
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public void add(ByteBuf buf, ChannelPromise promise) {
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// buffers are added before promises so that we naturally 'consume' the entire buffer during removal
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// before we complete it's promise.
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ObjectUtil.checkNotNull(promise, "promise");
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add(buf, promise.isVoid() ? null : new ChannelPromiseNotifier(promise));
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}
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/**
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* Add a buffer to the end of the queue and associate a listener with it that should be completed when
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* all the buffers bytes have been consumed from the queue and written.
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* @param buf to add to the tail of the queue
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* @param listener to notify when all the bytes have been consumed and written, can be {@code null}.
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*/
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public void add(ByteBuf buf, ChannelFutureListener listener) {
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// buffers are added before promises so that we naturally 'consume' the entire buffer during removal
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// before we complete it's promise.
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ObjectUtil.checkNotNull(buf, "buf");
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if (readableBytes > Integer.MAX_VALUE - buf.readableBytes()) {
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throw new IllegalStateException("buffer queue length overflow: " + readableBytes
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+ " + " + buf.readableBytes());
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}
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bufAndListenerPairs.add(buf);
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if (listener != null) {
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bufAndListenerPairs.add(listener);
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}
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readableBytes += buf.readableBytes();
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}
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/**
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* Remove a {@link ByteBuf} from the queue with the specified number of bytes. Any added buffer who's bytes are
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* fully consumed during removal will have it's promise completed when the passed aggregate {@link ChannelPromise}
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* completes.
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*
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* @param bytes the maximum number of readable bytes in the returned {@link ByteBuf}, if {@code bytes} is greater
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* than {@link #readableBytes} then a buffer of length {@link #readableBytes} is returned.
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* @param aggregatePromise used to aggregate the promises and listeners for the constituent buffers.
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* @return a {@link ByteBuf} composed of the enqueued buffers.
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*/
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public ByteBuf remove(int bytes, ChannelPromise aggregatePromise) {
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if (bytes < 0) {
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throw new IllegalArgumentException("bytes (expected >= 0): " + bytes);
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}
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ObjectUtil.checkNotNull(aggregatePromise, "aggregatePromise");
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// Use isEmpty rather than readableBytes==0 as we may have a promise associated with an empty buffer.
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if (bufAndListenerPairs.isEmpty()) {
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return Unpooled.EMPTY_BUFFER;
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}
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bytes = Math.min(bytes, readableBytes);
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ByteBuf toReturn = null;
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int originalBytes = bytes;
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for (;;) {
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Object entry = bufAndListenerPairs.poll();
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if (entry == null) {
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break;
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}
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if (entry instanceof ChannelFutureListener) {
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aggregatePromise.addListener((ChannelFutureListener) entry);
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continue;
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}
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ByteBuf entryBuffer = (ByteBuf) entry;
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if (entryBuffer.readableBytes() > bytes) {
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// Add the buffer back to the queue as we can't consume all of it.
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bufAndListenerPairs.addFirst(entryBuffer);
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if (bytes > 0) {
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// Take a slice of what we can consume and retain it.
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toReturn = compose(toReturn, entryBuffer.readSlice(bytes).retain());
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bytes = 0;
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}
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break;
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} else {
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toReturn = compose(toReturn, entryBuffer);
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bytes -= entryBuffer.readableBytes();
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}
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}
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readableBytes -= originalBytes - bytes;
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assert readableBytes >= 0;
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return toReturn;
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}
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/**
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* Compose the current buffer with another.
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*/
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private ByteBuf compose(ByteBuf current, ByteBuf next) {
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if (current == null) {
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return next;
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}
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if (current instanceof CompositeByteBuf) {
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CompositeByteBuf composite = (CompositeByteBuf) current;
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composite.addComponent(next);
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composite.writerIndex(composite.writerIndex() + next.readableBytes());
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return composite;
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}
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// Create a composite buffer to accumulate this pair and potentially all the buffers
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// in the queue. Using +2 as we have already dequeued current and next.
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CompositeByteBuf composite = channel.alloc().compositeBuffer(bufAndListenerPairs.size() + 2);
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composite.addComponent(current);
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composite.addComponent(next);
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return composite.writerIndex(current.readableBytes() + next.readableBytes());
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}
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/**
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* The number of readable bytes.
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*/
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public int readableBytes() {
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return readableBytes;
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}
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/**
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* Are there pending buffers in the queue.
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*/
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public boolean isEmpty() {
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return bufAndListenerPairs.isEmpty();
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}
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/**
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* Release all buffers in the queue and complete all listeners and promises.
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*/
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public void releaseAndFailAll(Throwable cause) {
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releaseAndCompleteAll(channel.newFailedFuture(cause));
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}
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private void releaseAndCompleteAll(ChannelFuture future) {
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readableBytes = 0;
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Throwable pending = null;
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for (;;) {
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Object entry = bufAndListenerPairs.poll();
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if (entry == null) {
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break;
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}
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try {
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if (entry instanceof ByteBuf) {
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ReferenceCountUtil.safeRelease(entry);
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} else {
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((ChannelFutureListener) entry).operationComplete(future);
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}
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} catch (Throwable t) {
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pending = t;
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}
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}
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if (pending != null) {
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throw new IllegalStateException(pending);
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}
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}
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/**
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* Copy all pending entries in this queue into the destination queue.
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* @param dest to copy pending buffers to.
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*/
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public void copyTo(CoalescingBufferQueue dest) {
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dest.bufAndListenerPairs.addAll(bufAndListenerPairs);
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dest.readableBytes += readableBytes;
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}
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}
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@ -0,0 +1,218 @@
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/*
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* Copyright 2015 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License, version 2.0 (the
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* "License"); you may not use this file except in compliance with the License. You may obtain a
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* copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under the License
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* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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* or implied. See the License for the specific language governing permissions and limitations under
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* the License.
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*/
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package io.netty.channel;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.Unpooled;
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import io.netty.channel.embedded.EmbeddedChannel;
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import io.netty.util.ReferenceCountUtil;
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import io.netty.util.concurrent.ImmediateEventExecutor;
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import org.junit.After;
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import org.junit.Before;
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import org.junit.Test;
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import org.mockito.MockitoAnnotations;
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import java.nio.charset.Charset;
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import static org.junit.Assert.assertSame;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertFalse;
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import static org.junit.Assert.assertTrue;
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/**
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* Tests for {@link CoalescingBufferQueue}.
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*/
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public class CoalescingBufferQueueTest {
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private ByteBuf cat;
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private ByteBuf mouse;
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private ByteBuf empty;
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private ChannelPromise catPromise, emptyPromise;
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private ChannelPromise voidPromise;
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private ChannelFutureListener mouseListener;
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private boolean mouseDone;
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private boolean mouseSuccess;
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private Channel channel = new EmbeddedChannel();
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private CoalescingBufferQueue writeQueue = new CoalescingBufferQueue(channel);
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@Before
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public void setup() {
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MockitoAnnotations.initMocks(this);
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catPromise = newPromise();
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mouseListener = new ChannelFutureListener() {
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@Override
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public void operationComplete(ChannelFuture future) throws Exception {
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mouseDone = true;
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mouseSuccess = future.isSuccess();
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}
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};
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emptyPromise = newPromise();
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voidPromise = channel.voidPromise();
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cat = Unpooled.wrappedBuffer("cat".getBytes(Charset.defaultCharset()));
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mouse = Unpooled.wrappedBuffer("mouse".getBytes(Charset.defaultCharset()));
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empty = Unpooled.buffer(0, 1);
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}
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@After
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public void tearDown() {
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ReferenceCountUtil.safeRelease(cat);
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ReferenceCountUtil.safeRelease(mouse);
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ReferenceCountUtil.safeRelease(empty);
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}
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@Test
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public void testAggregateWithFullRead() {
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writeQueue.add(cat, catPromise);
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assertQueueSize(3, false);
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writeQueue.add(mouse, mouseListener);
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assertQueueSize(8, false);
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DefaultChannelPromise aggregatePromise = newPromise();
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assertEquals("catmouse", writeQueue.remove(8, aggregatePromise).toString(Charset.defaultCharset()));
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assertQueueSize(0, true);
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assertFalse(catPromise.isSuccess());
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assertFalse(mouseDone);
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aggregatePromise.trySuccess();
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assertTrue(catPromise.isSuccess());
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assertTrue(mouseSuccess);
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}
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@Test
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public void testWithVoidPromise() {
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writeQueue.add(cat, voidPromise);
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writeQueue.add(mouse, voidPromise);
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writeQueue.add(empty, voidPromise);
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assertQueueSize(8, false);
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assertEquals("catm", writeQueue.remove(4, newPromise()).toString(Charset.defaultCharset()));
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assertQueueSize(4, false);
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assertEquals("ouse", writeQueue.remove(4, newPromise()).toString(Charset.defaultCharset()));
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assertQueueSize(0, true);
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}
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@Test
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public void testAggregateWithPartialRead() {
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writeQueue.add(cat, catPromise);
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writeQueue.add(mouse, mouseListener);
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DefaultChannelPromise aggregatePromise = newPromise();
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assertEquals("catm", writeQueue.remove(4, aggregatePromise).toString(Charset.defaultCharset()));
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assertQueueSize(4, false);
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assertFalse(catPromise.isSuccess());
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assertFalse(mouseDone);
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aggregatePromise.trySuccess();
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assertTrue(catPromise.isSuccess());
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assertFalse(mouseDone);
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aggregatePromise = newPromise();
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assertEquals("ouse", writeQueue.remove(Integer.MAX_VALUE, aggregatePromise).toString(Charset.defaultCharset()));
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assertQueueSize(0, true);
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assertFalse(mouseDone);
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aggregatePromise.trySuccess();
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assertTrue(mouseSuccess);
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}
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@Test
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public void testReadExactAddedBufferSizeReturnsOriginal() {
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writeQueue.add(cat, catPromise);
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writeQueue.add(mouse, mouseListener);
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DefaultChannelPromise aggregatePromise = newPromise();
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assertSame(cat, writeQueue.remove(3, aggregatePromise));
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assertFalse(catPromise.isSuccess());
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aggregatePromise.trySuccess();
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assertTrue(catPromise.isSuccess());
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aggregatePromise = newPromise();
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assertSame(mouse, writeQueue.remove(5, aggregatePromise));
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assertFalse(mouseDone);
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aggregatePromise.trySuccess();
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assertTrue(mouseSuccess);
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}
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@Test
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public void testReadEmptyQueueReturnsEmptyBuffer() {
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assertQueueSize(0, true);
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DefaultChannelPromise aggregatePromise = newPromise();
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assertEquals(0, writeQueue.remove(Integer.MAX_VALUE, aggregatePromise).readableBytes());
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assertQueueSize(0, true);
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}
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@Test
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public void testReleaseAndFailAll() {
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writeQueue.add(cat, catPromise);
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writeQueue.add(mouse, mouseListener);
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RuntimeException cause = new RuntimeException("ooops");
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writeQueue.releaseAndFailAll(cause);
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DefaultChannelPromise aggregatePromise = newPromise();
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assertQueueSize(0, true);
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assertEquals(0, cat.refCnt());
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assertEquals(0, mouse.refCnt());
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assertSame(cause, catPromise.cause());
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assertEquals(0, writeQueue.remove(Integer.MAX_VALUE, aggregatePromise).readableBytes());
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assertQueueSize(0, true);
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}
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@Test
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public void testEmptyBuffersAreCoalesced() {
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assertQueueSize(0, true);
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writeQueue.add(cat, catPromise);
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writeQueue.add(empty, emptyPromise);
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assertQueueSize(3, false);
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DefaultChannelPromise aggregatePromise = newPromise();
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ByteBuf removed = writeQueue.remove(3, aggregatePromise);
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assertQueueSize(0, true);
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assertEquals("cat", removed.toString(Charset.defaultCharset()));
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assertFalse(catPromise.isSuccess());
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assertFalse(emptyPromise.isSuccess());
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aggregatePromise.trySuccess();
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assertTrue(catPromise.isSuccess());
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assertTrue(emptyPromise.isSuccess());
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removed.release();
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assertEquals(0, cat.refCnt());
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assertEquals(0, empty.refCnt());
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}
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@Test
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public void testMerge() {
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writeQueue.add(cat, catPromise);
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CoalescingBufferQueue otherQueue = new CoalescingBufferQueue(channel);
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otherQueue.add(mouse, mouseListener);
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otherQueue.copyTo(writeQueue);
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assertQueueSize(8, false);
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DefaultChannelPromise aggregatePromise = newPromise();
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assertEquals("catmouse", writeQueue.remove(8, aggregatePromise).toString(Charset.defaultCharset()));
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assertQueueSize(0, true);
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assertFalse(catPromise.isSuccess());
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assertFalse(mouseDone);
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aggregatePromise.trySuccess();
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assertTrue(catPromise.isSuccess());
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assertTrue(mouseSuccess);
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}
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private DefaultChannelPromise newPromise() {
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return new DefaultChannelPromise(channel, ImmediateEventExecutor.INSTANCE);
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}
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private void assertQueueSize(int size, boolean isEmpty) {
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assertEquals(size, writeQueue.readableBytes());
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if (isEmpty) {
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assertTrue(writeQueue.isEmpty());
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} else {
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assertFalse(writeQueue.isEmpty());
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}
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}
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}
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