Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package org.apache.cxf.transport.http.asyncclient; import java.io.IOException; import java.io.InterruptedIOException; import java.nio.ByteBuffer; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.ReentrantLock; import org.apache.http.annotation.ThreadSafe; import org.apache.http.nio.ContentDecoder; import org.apache.http.nio.IOControl; import org.apache.http.nio.util.ByteBufferAllocator; import org.apache.http.nio.util.ExpandableBuffer; /** * Content buffer that can be shared by multiple threads, usually the I/O dispatch of * an I/O reactor and a worker thread. * <p/> * The I/O dispatch thread is expect to transfer data from {@link ContentDecoder} to the buffer * by calling {@link #consumeContent(ContentDecoder)}. * <p/> * The worker thread is expected to read the data from the buffer by calling * {@link #read()} or {@link #read(byte[], int, int)} methods. * <p/> * In case of an abnormal situation or when no longer needed the buffer must be shut down * using {@link #shutdown()} method. */ @ThreadSafe public class SharedInputBuffer extends ExpandableBuffer { private final ReentrantLock lock; private final Condition condition; private final int requestInputSize; private volatile IOControl ioctrl; private volatile boolean shutdown; private volatile boolean endOfStream; private volatile ByteBuffer waitingBuffer; //private volatile int waitCnt; //private volatile int nowaitCnt; public SharedInputBuffer(int buffersize, final ByteBufferAllocator allocator) { super(buffersize, allocator); this.lock = new ReentrantLock(); this.condition = this.lock.newCondition(); //if the buffer become 3/4 empty, we'll turn on the input //events again to hopefully get more data before the next //the buffer fully empties and we have to wait to read this.requestInputSize = buffersize * 3 / 4; } public void reset() { if (this.shutdown) { return; } this.lock.lock(); try { clear(); this.endOfStream = false; } finally { this.lock.unlock(); } } public int consumeContent(final ContentDecoder decoder, final IOControl ioc) throws IOException { if (this.shutdown) { //something bad happened, we need to shutdown the connection //as we're not going to read the data at all and we //don't want to keep getting read notices and such ioc.shutdown(); return -1; } this.lock.lock(); try { this.ioctrl = ioc; setInputMode(); int totalRead = 0; int bytesRead; if (waitingBuffer != null && this.buffer.position() == 0) { while ((bytesRead = decoder.read(this.waitingBuffer)) > 0) { totalRead += bytesRead; } } //read more while ((bytesRead = decoder.read(this.buffer)) > 0) { totalRead += bytesRead; } if (bytesRead == -1 || decoder.isCompleted()) { this.endOfStream = true; } if (!this.buffer.hasRemaining() && this.ioctrl != null) { this.ioctrl.suspendInput(); } this.condition.signalAll(); if (totalRead > 0) { return totalRead; } else { if (this.endOfStream) { return -1; } else { return 0; } } } finally { this.lock.unlock(); } } @Override public boolean hasData() { this.lock.lock(); try { return super.hasData(); } finally { this.lock.unlock(); } } @Override public int available() { this.lock.lock(); try { return super.length(); } finally { this.lock.unlock(); } } @Override public int capacity() { this.lock.lock(); try { return super.capacity(); } finally { this.lock.unlock(); } } @Override public int length() { this.lock.lock(); try { return super.length(); } finally { this.lock.unlock(); } } protected void waitForData(int waitPos) throws IOException { this.lock.lock(); try { try { while (true) { if (this.waitingBuffer != null && this.waitingBuffer.position() > waitPos) { return; } if (super.hasData()) { return; } if (this.endOfStream) { return; } if (this.shutdown) { throw new InterruptedIOException("Input operation aborted"); } if (this.ioctrl != null) { this.ioctrl.requestInput(); } this.condition.await(); } } catch (InterruptedException ex) { throw new IOException("Interrupted while waiting for more data"); } } finally { this.lock.unlock(); } } public void close() { if (this.shutdown) { return; } this.endOfStream = true; this.lock.lock(); try { this.condition.signalAll(); } finally { this.lock.unlock(); } } public void shutdown() { if (this.shutdown) { return; } this.shutdown = true; this.lock.lock(); try { this.condition.signalAll(); } finally { this.lock.unlock(); } } protected boolean isShutdown() { return this.shutdown; } protected boolean isEndOfStream() { return this.shutdown || (!hasData() && this.endOfStream); } public int read() throws IOException { if (this.shutdown) { return -1; } this.lock.lock(); try { if (!super.hasData()) { waitForData(0); } if (isEndOfStream()) { return -1; } setOutputMode(); return this.buffer.get() & 0xff; } finally { this.lock.unlock(); } } public int read(final byte[] b, int off, int len) throws IOException { if (this.shutdown) { return -1; } if (b == null) { return 0; } this.lock.lock(); try { if (!hasData()) { this.waitingBuffer = ByteBuffer.wrap(b, off, len); waitForData(off); int i = waitingBuffer.position() - off; waitingBuffer = null; if (i > 0) { //++waitCnt; return i; } } if (isEndOfStream()) { //System.out.println(waitCnt + " " + nowaitCnt); return -1; } setOutputMode(); int chunk = len; if (chunk > this.buffer.remaining()) { chunk = this.buffer.remaining(); } this.buffer.get(b, off, chunk); if (this.buffer.position() >= this.requestInputSize && !this.endOfStream && this.ioctrl != null) { //we have a significant amount of space empty in the buffer, we'll turn on //the input so maybe we'll get another chunk by the time the next read happens //and we can then avoid waiting for input this.ioctrl.requestInput(); } //++nowaitCnt; return chunk; } finally { this.lock.unlock(); } } public int read(final byte[] b) throws IOException { if (this.shutdown) { return -1; } if (b == null) { return 0; } return read(b, 0, b.length); } }