97 lines
3.2 KiB
C#
97 lines
3.2 KiB
C#
//------------------------------------------------------------
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//------------------------------------------------------------
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namespace System.ServiceModel.Channels
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{
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using System.IO;
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using System.Xml;
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using System.Diagnostics;
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abstract class BufferedMessageWriter
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{
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int[] sizeHistory;
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int sizeHistoryIndex;
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const int sizeHistoryCount = 4;
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const int expectedSizeVariance = 256;
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BufferManagerOutputStream stream;
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public BufferedMessageWriter()
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{
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this.stream = new BufferManagerOutputStream(SR.MaxSentMessageSizeExceeded);
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InitMessagePredicter();
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}
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protected abstract XmlDictionaryWriter TakeXmlWriter(Stream stream);
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protected abstract void ReturnXmlWriter(XmlDictionaryWriter writer);
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public ArraySegment<byte> WriteMessage(Message message, BufferManager bufferManager, int initialOffset, int maxSizeQuota)
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{
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int effectiveMaxSize;
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// make sure that maxSize has room for initialOffset without overflowing, since
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// the effective buffer size is message size + initialOffset
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if (maxSizeQuota <= int.MaxValue - initialOffset)
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effectiveMaxSize = maxSizeQuota + initialOffset;
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else
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effectiveMaxSize = int.MaxValue;
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int predictedMessageSize = PredictMessageSize();
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if (predictedMessageSize > effectiveMaxSize)
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predictedMessageSize = effectiveMaxSize;
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else if (predictedMessageSize < initialOffset)
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predictedMessageSize = initialOffset;
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try
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{
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stream.Init(predictedMessageSize, maxSizeQuota, effectiveMaxSize, bufferManager);
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stream.Skip(initialOffset);
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XmlDictionaryWriter writer = TakeXmlWriter(stream);
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OnWriteStartMessage(writer);
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message.WriteMessage(writer);
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OnWriteEndMessage(writer);
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writer.Flush();
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ReturnXmlWriter(writer);
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int size;
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byte[] buffer = stream.ToArray(out size);
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RecordActualMessageSize(size);
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return new ArraySegment<byte>(buffer, initialOffset, size - initialOffset);
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}
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finally
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{
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stream.Clear();
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}
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}
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protected virtual void OnWriteStartMessage(XmlDictionaryWriter writer)
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{
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}
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protected virtual void OnWriteEndMessage(XmlDictionaryWriter writer)
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{
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}
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void InitMessagePredicter()
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{
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sizeHistory = new int[4];
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for (int i = 0; i < sizeHistoryCount; i++)
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sizeHistory[i] = 256;
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}
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int PredictMessageSize()
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{
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int max = 0;
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for (int i = 0; i < sizeHistoryCount; i++)
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if (sizeHistory[i] > max)
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max = sizeHistory[i];
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return max + expectedSizeVariance;
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}
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void RecordActualMessageSize(int size)
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{
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sizeHistory[sizeHistoryIndex] = size;
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sizeHistoryIndex = (sizeHistoryIndex + 1) % sizeHistoryCount;
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}
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}
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}
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