diff options
Diffstat (limited to 'qpid/dotnet/Qpid.Codec/CumulativeProtocolDecoder.cs')
-rw-r--r-- | qpid/dotnet/Qpid.Codec/CumulativeProtocolDecoder.cs | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/qpid/dotnet/Qpid.Codec/CumulativeProtocolDecoder.cs b/qpid/dotnet/Qpid.Codec/CumulativeProtocolDecoder.cs new file mode 100644 index 0000000000..6cfd75c851 --- /dev/null +++ b/qpid/dotnet/Qpid.Codec/CumulativeProtocolDecoder.cs @@ -0,0 +1,152 @@ +/* + * + * 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. + * + */ +using System; +using log4net; +using Apache.Qpid.Buffer; + +namespace Apache.Qpid.Codec +{ + public abstract class CumulativeProtocolDecoder : IProtocolDecoder + { + static ILog _logger = LogManager.GetLogger(typeof(CumulativeProtocolDecoder)); + + ByteBuffer _remaining; + + /// <summary> + /// Creates a new instance with the 4096 bytes initial capacity of + /// cumulative buffer. + /// </summary> + protected CumulativeProtocolDecoder() + { + _remaining = AllocateBuffer(); + } + + /// <summary> + /// Cumulates content of <tt>in</tt> into internal buffer and forwards + /// decoding request to {@link #doDecode(IoSession, ByteBuffer, ProtocolDecoderOutput)}. + /// <tt>doDecode()</tt> is invoked repeatedly until it returns <tt>false</tt> + /// and the cumulative buffer is compacted after decoding ends. + /// </summary> + /// <exception cref="Exception"> + /// if your <tt>doDecode()</tt> returned <tt>true</tt> not consuming the cumulative buffer. + /// </exception> + public void Decode(ByteBuffer input, IProtocolDecoderOutput output) + { + if ( _remaining.Position != 0 ) // If there were remaining undecoded bytes + { + DecodeRemainingAndInput(input, output); + } else + { + DecodeInput(input, output); + } + } + + private void DecodeInput(ByteBuffer input, IProtocolDecoderOutput output) + { + _logger.Debug(string.Format("DecodeInput: input {0}", input.Remaining)); + // Just decode the input buffer and remember any remaining undecoded bytes. + try + { + DecodeAll(input, output); + } finally + { + if ( input.HasRemaining ) + { + _remaining.Put(input); + } + } + } + + private void DecodeRemainingAndInput(ByteBuffer input, IProtocolDecoderOutput output) + { + _logger.Debug(string.Format("DecodeRemainingAndInput: input {0}, remaining {1}", input.Remaining, _remaining.Position)); + // replace the _remainder buffer, so that we can leave the + // original one alone. Necessary because some consumer splice + // the buffer and only consume it until later, causing + // a race condition if we compact it too soon. + ByteBuffer newRemainding = AllocateBuffer(); + ByteBuffer temp = _remaining; + _remaining = newRemainding; + temp.Put(input); + temp.Flip(); + try + { + DecodeAll(temp, output); + } finally + { + if ( temp.Remaining > 0 ) + _remaining.Put(temp); + } + } + + private void DecodeAll(ByteBuffer buf, IProtocolDecoderOutput output) + { + for ( ; ; ) + { + int oldPos = buf.Position; + bool decoded = DoDecode(buf, output); + if ( decoded ) + { + if ( buf.Position == oldPos ) + { + throw new Exception( + "doDecode() can't return true when buffer is not consumed."); + } + + if ( !buf.HasRemaining ) + { + break; + } + } else + { + break; + } + } + } + + /// <summary> + /// Implement this method to consume the specified cumulative buffer and + /// decode its content into message(s). + /// </summary> + /// <param name="input">the cumulative buffer</param> + /// <param name="output">decoder output</param> + /// <returns> + /// <tt>true</tt> if and only if there's more to decode in the buffer + /// and you want to have <tt>doDecode</tt> method invoked again. + /// Return <tt>false</tt> if remaining data is not enough to decode, + /// then this method will be invoked again when more data is cumulated. + /// </returns> + /// <exception cref="Exception">If cannot decode</exception> + protected abstract bool DoDecode(ByteBuffer input, IProtocolDecoderOutput output); + + public void Dispose() + { + _remaining = null; + } + + private ByteBuffer AllocateBuffer() + { + ByteBuffer buffer = ByteBuffer.Allocate(4096); + buffer.IsAutoExpand = true; + return buffer; + } + } +} |