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.synapse.transport.nhttp; 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.ContentOutputBuffer; import org.apache.http.nio.util.ExpandableBuffer; import org.apache.http.nio.util.HeapByteBufferAllocator; import org.apache.http.util.Args; import org.apache.http.util.Asserts; import java.io.IOException; import java.io.InterruptedIOException; import java.util.concurrent.TimeUnit; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.ReentrantLock; /** * Implementation of the {@link ContentOutputBuffer} interface 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. * * Please note that {@link org.apache.http.nio.util.SharedOutputBuffer} class was copied here renamed as * NhttpSharedOutputBuffer from httpcore-nio in order to fix * https://github.com/wso2/product-ei/issues/1367, without having to do an API change in httpcore-nio component. */ @ThreadSafe public class NhttpSharedOutputBuffer extends ExpandableBuffer implements ContentOutputBuffer { private final ReentrantLock lock; private final Condition condition; private volatile IOControl ioctrl; private volatile boolean shutdown = false; private volatile boolean endOfStream = false; private int timeout = 0; /** * Boolean state to identify whether write condition await interrupted or timeout exceeded. * Normal behaviour should be the interruption of the await. If something went wrong and the write condition * did not got any notification to allow write to the buffer, the await will timeout after socket timeout * value specified in the nttp.properties file. * "true" - if interrupted * "false"- if time out exceeds */ private boolean awaitInterrupted = true; public NhttpSharedOutputBuffer(final int buffersize, final IOControl ioctrl, final ByteBufferAllocator allocator, int timeout) { super(buffersize, allocator); Args.notNull(ioctrl, "I/O content control"); this.ioctrl = ioctrl; this.lock = new ReentrantLock(); this.condition = this.lock.newCondition(); this.timeout = timeout; } @Deprecated public NhttpSharedOutputBuffer(final int buffersize, final IOControl ioctrl, final ByteBufferAllocator allocator) { super(buffersize, allocator); Args.notNull(ioctrl, "I/O content control"); this.ioctrl = ioctrl; this.lock = new ReentrantLock(); this.condition = this.lock.newCondition(); } public NhttpSharedOutputBuffer(final int buffersize, final ByteBufferAllocator allocator) { super(buffersize, allocator); this.lock = new ReentrantLock(); this.condition = this.lock.newCondition(); } public NhttpSharedOutputBuffer(final int buffersize) { this(buffersize, HeapByteBufferAllocator.INSTANCE); } /** * {@inheritDoc} */ public void reset() { if (this.shutdown) { return; } this.lock.lock(); try { clear(); this.endOfStream = false; } finally { this.lock.unlock(); } } /** * {@inheritDoc} */ @Override public boolean hasData() { this.lock.lock(); try { return super.hasData(); } finally { this.lock.unlock(); } } /** * {@inheritDoc} */ @Override public int available() { this.lock.lock(); try { return super.available(); } finally { this.lock.unlock(); } } /** * {@inheritDoc} */ @Override public int capacity() { this.lock.lock(); try { return super.capacity(); } finally { this.lock.unlock(); } } /** * {@inheritDoc} */ @Override public int length() { this.lock.lock(); try { return super.length(); } finally { this.lock.unlock(); } } /** * {@inheritDoc} */ @Deprecated public int produceContent(final ContentEncoder encoder) throws IOException { return produceContent(encoder, null); } public int produceContent(final ContentEncoder encoder, final IOControl ioctrl) throws IOException { if (this.shutdown) { return -1; } this.lock.lock(); try { if (ioctrl != null) { this.ioctrl = ioctrl; } setOutputMode(); int bytesWritten = 0; if (super.hasData()) { bytesWritten = encoder.write(this.buffer); if (encoder.isCompleted()) { this.endOfStream = true; } } if (!super.hasData()) { // No more buffered content // If at the end of the stream, terminate if (this.endOfStream && !encoder.isCompleted()) { encoder.complete(); } if (!this.endOfStream) { // suspend output events if (this.ioctrl != null) { this.ioctrl.suspendOutput(); } } } 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(); } } /** * {@inheritDoc} */ public void write(final byte[] b, final int off, final int len) throws IOException { if (b == null) { return; } int pos = off; this.lock.lock(); try { Asserts.check(!this.shutdown && !this.endOfStream, "Buffer already closed for writing"); // Set buffer to write mode setInputMode(); int remaining = len; while (remaining > 0) { // At the moment buffer is in the write mode. So position equals to capacity. // if position >= limit(= capacity) -> true i.e. buffer is full // If this buffer is full, that means the data should be written to output buffer (Need to flush). if (!this.buffer.hasRemaining()) { flushContent(); // If awaitInterrupted was set to false, that means something went wrong(timeout happened) // therefore, we clear the buffer and stop the flow with an exception. if (!awaitInterrupted) { this.buffer.clear(); throw new IOException("Output buffer write time out exceeded"); } // Set buffer to write mode. (Inside flushContent method, buffer was set to read mode) setInputMode(); } final int chunk = Math.min(remaining, this.buffer.remaining()); this.buffer.put(b, pos, chunk); remaining -= chunk; pos += chunk; } } finally { this.lock.unlock(); } } public void write(final byte[] b) throws IOException { if (b == null) { return; } write(b, 0, b.length); } /** * {@inheritDoc} */ public void write(final int b) throws IOException { this.lock.lock(); try { Asserts.check(!this.shutdown && !this.endOfStream, "Buffer already closed for writing"); // Set buffer to write mode setInputMode(); // At the moment buffer is in the write mode. So position equals to capacity. // if position >= limit(= capacity) -> true i.e. buffer is full // If this buffer is full, that means the data should be written to output buffer (Need to flush). if (!this.buffer.hasRemaining()) { flushContent(); // If "awaitInterrupted" was set to false, that means something went wrong(timeout happened) // therefore, we clear the buffer and stop the flow with an exception. if (!awaitInterrupted) { this.buffer.clear(); throw new IOException("Output buffer write time out exceeded"); } // Set buffer to write mode. (Inside flushContent method, buffer was set to read mode) setInputMode(); } this.buffer.put((byte) b); } finally { this.lock.unlock(); } } /** * {@inheritDoc} */ public void flush() throws IOException { } /** * Flushes the content in the buffer if any. * * @throws IOException Thrown if the thread was interrupted while flushing */ private void flushContent() throws IOException { this.lock.lock(); try { try { // hasData sets the buffer to read mode and calls hasRemaining method and returns the result. // if position (= initially 0, incremented as data is read) < limit(= how much bytes have been written // to the buffer) -> true i.e. there is data to be read while (super.hasData()) { if (this.shutdown) { throw new InterruptedIOException("Output operation aborted"); } // Request event notifications to be triggered when the underlying // channel is ready for output operations. if (this.ioctrl != null) { this.ioctrl.requestOutput(); } // Ask the thread which is reading this buffer to wait for a notification to // write data out awaitInterrupted = this.condition.await(timeout, TimeUnit.MILLISECONDS); // If socket timeout happens before the thread is notified, then we don't care whether there is // data or not, but honor the socket timeout config and break the loop if (!awaitInterrupted) { break; } } } catch (final InterruptedException ex) { throw new IOException("Interrupted while flushing the content buffer"); } } finally { this.lock.unlock(); } } /** * {@inheritDoc} */ 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(); } } }