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.InputStream; 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.ContentEncoder; 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 expected to transfer data from the buffer to * {@link ContentEncoder} by calling {@link #produceContent(ContentEncoder)}. * <p/> * The worker thread is expected to write data to the buffer by calling * {@link #write(int)}, {@link #write(byte[], int, int)} or {@link #writeCompleted()} * <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 SharedOutputBuffer extends ExpandableBuffer { private final ReentrantLock lock; private final Condition condition; private volatile IOControl ioctrl; private volatile boolean shutdown; private volatile boolean endOfStream; private volatile ByteBuffer largeWrapper; public SharedOutputBuffer(int buffersize, final ByteBufferAllocator allocator) { super(buffersize, allocator); this.lock = new ReentrantLock(); this.condition = this.lock.newCondition(); } public void reset() { if (this.shutdown) { return; } this.lock.lock(); try { clear(); this.endOfStream = false; } 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.available(); } 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(); } } public int produceContent(final ContentEncoder encoder, final IOControl ioc) throws IOException { if (this.shutdown) { return -1; } this.lock.lock(); try { this.ioctrl = ioc; setOutputMode(); int bytesWritten = 0; if (largeWrapper != null || super.hasData()) { if (!this.buffer.hasRemaining() && largeWrapper != null) { bytesWritten = encoder.write(largeWrapper); } else { bytesWritten = encoder.write(this.buffer); } if (encoder.isCompleted()) { this.endOfStream = true; } } if ((largeWrapper == null || !largeWrapper.hasRemaining()) && !super.hasData()) { // No more buffered content // If at the end of the stream, terminate if (this.endOfStream && !encoder.isCompleted()) { encoder.complete(); } if (!this.endOfStream && this.ioctrl != null) { // suspend output events this.ioctrl.suspendOutput(); } } // no need to signal if the large wrapper is present and has data remaining if (largeWrapper == null || !largeWrapper.hasRemaining()) { this.condition.signalAll(); } return bytesWritten; } finally { this.lock.unlock(); } } public void close() { shutdown(); } public void shutdown() { if (this.shutdown) { return; } this.shutdown = true; this.lock.lock(); try { this.condition.signalAll(); } finally { this.lock.unlock(); } } public int copy(InputStream in) throws IOException { this.lock.lock(); int total = 0; try { if (this.shutdown || this.endOfStream) { throw new IllegalStateException("Buffer already closed for writing"); } setInputMode(); int i = 0; boolean yielded = false; while (i != -1) { if (!this.buffer.hasRemaining()) { flushContent(); setInputMode(); } i = in.available(); if (i == 0 && !yielded) { //nothing avail right now, we'll attempt an //output, but not really force a flush. if (buffer.position() != 0 && this.ioctrl != null) { this.ioctrl.requestOutput(); } try { condition.awaitNanos(1); } catch (InterruptedException e) { //ignore } setInputMode(); yielded = true; } else { int p = this.buffer.position(); i = in.read(this.buffer.array(), this.buffer.position(), this.buffer.remaining()); yielded = false; if (i != -1) { total += i; buffer.position(p + i); } /* System.out.println("p: " + p + " " + i + " " + this.buffer.position() + " " + this.buffer.hasRemaining()); */ } } } finally { this.lock.unlock(); } return total; } public void write(final byte[] b, int off, int len) throws IOException { if (b == null) { return; } this.lock.lock(); try { if (this.shutdown || this.endOfStream) { throw new IllegalStateException("Buffer already closed for writing"); } setInputMode(); int remaining = len; while (remaining > 0) { if (!this.buffer.hasRemaining()) { flushContent(); setInputMode(); } if (buffer.position() == 0 && (this.buffer.remaining() * 2) < remaining) { largeWrapper = ByteBuffer.wrap(b, off, remaining); while (largeWrapper.hasRemaining()) { flushContent(); } largeWrapper = null; remaining = 0; } else { int chunk = Math.min(remaining, this.buffer.remaining()); this.buffer.put(b, off, chunk); remaining -= chunk; off += chunk; } } } finally { this.lock.unlock(); } } public int write(ByteBuffer b) throws IOException { if (b == null) { return 0; } this.lock.lock(); try { if (this.shutdown || this.endOfStream) { throw new IllegalStateException("Buffer already closed for writing"); } setInputMode(); if (!this.buffer.hasRemaining()) { flushContent(); setInputMode(); } int c = b.limit() - b.position(); largeWrapper = b; while (largeWrapper.hasRemaining()) { flushContent(); } largeWrapper = null; return c; } finally { this.lock.unlock(); } } public void write(final byte[] b) throws IOException { if (b == null) { return; } write(b, 0, b.length); } public void write(int b) throws IOException { this.lock.lock(); try { if (this.shutdown || this.endOfStream) { throw new IllegalStateException("Buffer already closed for writing"); } setInputMode(); if (!this.buffer.hasRemaining()) { flushContent(); setInputMode(); } this.buffer.put((byte) b); } finally { this.lock.unlock(); } } public void flush() throws IOException { } private void flushContent() throws IOException { this.lock.lock(); try { try { while ((largeWrapper != null && largeWrapper.hasRemaining()) || super.hasData()) { if (this.shutdown) { throw new InterruptedIOException("Output operation aborted"); } if (this.ioctrl != null) { this.ioctrl.requestOutput(); } this.condition.await(); } } catch (InterruptedException ex) { throw new IOException("Interrupted while flushing the content buffer"); } } finally { this.lock.unlock(); } } public void writeCompleted() throws IOException { this.lock.lock(); try { if (this.endOfStream) { return; } this.endOfStream = true; if (this.ioctrl != null) { this.ioctrl.requestOutput(); } } finally { this.lock.unlock(); } } }