|
//------------------------------------------------------------------------------
// Microsoft Avalon
// Copyright (c) Microsoft Corporation, 2001
//
// File: ResponseStream.cs
//
// Description: Exists so that the gc lifetime for the container
// and the webresponse are shared.
//
// This wrapper is returned for any PackWebResponse satisified
// with a container. It ensures that the container lives until
// the stream is closed because we are unaware of the lifetime of
// the stream and the client is unaware of the existence of the
// container.
//
// Container is never closed because it may be used by other
// responses.
//
// History: 11/17/03 - brucemac - created
// 12/11/03 - brucemac - adapted from ResponseStream
// 15/10/04 - brucemac - adapted from ContainerResponseStream
//------------------------------------------------------------------------------
using System;
using System.Diagnostics;
using System.IO;
using System.IO.Packaging; // for PackWebResponse
using MS.Utility;
using System.Windows;
namespace MS.Internal.IO.Packaging
{
/// <summary>
/// Wrap returned stream so we can release the webresponse container when the stream is closed
/// </summary>
internal class ResponseStream : Stream
{
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
/// <summary>
/// Wraps PackWebResponse to ensure correct lifetime handling and stream length functionality
/// </summary>
/// <param name="s">stream to read from (baseStream)</param>
/// <param name="response">response</param>
/// <param name="owningStream">stream under the package</param>
/// <param name="container">container to hold on to</param>
internal ResponseStream(Stream s, PackWebResponse response, Stream owningStream, Package container)
{
Debug.Assert(container != null, "Logic error: use other constructor for full package request streams");
Debug.Assert(owningStream != null, "Logic error: use other constructor for full package request streams");
Init(s, response, owningStream, container);
}
/// <summary>
/// Wraps stream returned by PackWebResponse to ensure correct lifetime handlingy
/// </summary>
/// <param name="s">stream to read from (baseStream)</param>
/// <param name="response">webresponse to close when we close</param>
internal ResponseStream(Stream s, PackWebResponse response)
{
Init(s, response, null, null);
}
/// <summary>
/// Wraps PackWebResponse to ensure correct lifetime handling and stream length functionality
/// </summary>
/// <param name="s">stream to read from (baseStream)</param>
/// <param name="owningStream">stream under the container</param>
/// <param name="response">response</param>
/// <param name="container">container to hold on to</param>
private void Init(Stream s, PackWebResponse response, Stream owningStream, Package container)
{
Debug.Assert(s != null, "Logic error: base stream cannot be null");
Debug.Assert(response != null, "Logic error: response cannot be null");
_innerStream = s;
_response = response;
_owningStream = owningStream;
_container = container;
}
//------------------------------------------------------
//
// Public Methods
//
//------------------------------------------------------
/// <summary>
/// Return the bytes requested
/// </summary>
/// <param name="buffer">destination buffer</param>
/// <param name="offset">offset to write into that buffer</param>
/// <param name="count">how many bytes requested</param>
/// <returns>how many bytes were written into buffer</returns>
/// <remarks>
/// Blocks until data is available.
/// The read semantics, and in particular the restoration of the position in case of an
/// exception, is implemented by the inner stream, i.e. the stream returned by PackWebResponse.
/// </remarks>
public override int Read(byte[] buffer, int offset, int count)
{
EventTrace.EasyTraceEvent(EventTrace.Keyword.KeywordXPS, EventTrace.Level.Verbose, EventTrace.Event.WClientDRXReadStreamBegin, count);
CheckDisposed();
int rslt = _innerStream.Read(buffer, offset, count);
EventTrace.EasyTraceEvent(EventTrace.Keyword.KeywordXPS, EventTrace.Level.Verbose, EventTrace.Event.WClientDRXReadStreamEnd, rslt);
return rslt;
}
/// <summary>
/// Seek
/// </summary>
/// <param name="offset">only zero is supported</param>
/// <param name="origin">only SeekOrigin.Begin is supported</param>
/// <returns>zero</returns>
public override long Seek(long offset, SeekOrigin origin)
{
CheckDisposed();
return _innerStream.Seek(offset, origin);
}
/// <summary>
/// SetLength
/// </summary>
/// <exception cref="NotSupportedException">not supported</exception>
public override void SetLength(long newLength)
{
CheckDisposed();
_innerStream.SetLength(newLength);
}
/// <summary>
/// Write
/// </summary>
/// <exception cref="NotSupportedException">not supported</exception>
public override void Write(byte[] buf, int offset, int count)
{
CheckDisposed();
_innerStream.Write(buf, offset, count);
}
/// <summary>
/// Flush
/// </summary>
/// <exception cref="NotSupportedException">not supported</exception>
public override void Flush()
{
CheckDisposed();
_innerStream.Flush();
}
//------------------------------------------------------
//
// Public Properties
//
//------------------------------------------------------
/// <summary>
/// Is stream readable?
/// </summary>
public override bool CanRead
{
get
{
return (!_closed && _innerStream.CanRead);
}
}
/// <summary>
/// Is stream seekable?
/// </summary>
/// <remarks>We MUST support seek as this is used to implement ILockBytes.ReadAt()</remarks>
public override bool CanSeek
{
get
{
return (!_closed && _innerStream.CanSeek);
}
}
/// <summary>
/// Is stream writeable?
/// </summary>
public override bool CanWrite
{
get
{
return (!_closed && _innerStream.CanWrite);
}
}
/// <summary>
/// Logical byte position in this stream
/// </summary>
public override long Position
{
get
{
CheckDisposed();
return _innerStream.Position;
}
set
{
CheckDisposed();
_innerStream.Position = value;
}
}
/// <summary>
/// Length
/// </summary>
public override long Length
{
get
{
CheckDisposed();
// inner stream should always know its length because it's based on a local file
// or because it's on a NetStream that can fake this
return _innerStream.Length;
}
}
//------------------------------------------------------
//
// Protected Methods
//
//------------------------------------------------------
protected override void Dispose(bool disposing)
{
try
{
if (disposing && !_closed)
{
#if DEBUG
if (PackWebRequestFactory._traceSwitch.Enabled)
System.Diagnostics.Trace.TraceInformation("ContainerResponseStream.Dispose(bool)");
#endif
_container = null;
// close the Part or NetStream
_innerStream.Close();
if (_owningStream != null)
{
// in this case, the innerStream was the part so this is the NetStream
_owningStream.Close();
}
}
}
finally
{
_innerStream = null;
_owningStream = null;
_response = null;
_closed = true;
base.Dispose(disposing);
}
}
//------------------------------------------------------
//
// Private Methods
//
//------------------------------------------------------
private void CheckDisposed()
{
if (_closed)
throw new ObjectDisposedException("ResponseStream");
}
//------------------------------------------------------
//
// Private Fields
//
//------------------------------------------------------
private bool _closed; // prevent recursion
private Stream _innerStream; // stream we are emulating
private Package _container; // container to release when we are closed
private Stream _owningStream; // stream under the _innerStream when opening a Part
private PackWebResponse _response; // packWebResponse we can consult for reliable length
}
}
|