异步调用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Test
{
//Streams created are read only and return 0 once a full server reply has been read
//To get the next server reply, call GetNextReplyReader
class SmtpReplyReaderFactory
{
enum ReadState
{
Status0,
Status1,
Status2,
ContinueFlag,
ContinueCR,
ContinueLF,
LastCR,
LastLF,
Done
}

BufferedReadStream bufferedStream;
byte[] byteBuffer;
char[] charBuffer;
SmtpReplyReader currentReader;
const int DefaultBufferSize = 256;
ReadState readState = ReadState.Status0;
SmtpStatusCode statusCode;

internal SmtpReplyReaderFactory(Stream stream)
{
bufferedStream = new BufferedReadStream(stream);
}

internal SmtpReplyReader CurrentReader
{
get
{
return currentReader;
}
}

internal SmtpStatusCode StatusCode
{
get
{
return statusCode;
}
}

/* Consider removing
internal IAsyncResult BeginClose(SmtpReplyReader caller, AsyncCallback callback, object state)
{
CloseAsyncResult result = new CloseAsyncResult(this, callback, state);
result.Close(caller);
return result;
}
*/
/*
internal IAsyncResult BeginRead(SmtpReplyReader caller, byte[] buffer, int offset, int count, AsyncCallback callback, object state)
{
ReadAsyncResult result = new ReadAsyncResult(this, buffer, offset, count, callback, state);
result.Read(caller);
return result;
}
*/

internal IAsyncResult BeginReadLines(SmtpReplyReader caller, AsyncCallback callback, object state)
{
ReadLinesAsyncResult result = new ReadLinesAsyncResult(this, callback, state);
result.Read(caller);
return result;
}

internal IAsyncResult BeginReadLine(SmtpReplyReader caller, AsyncCallback callback, object state)
{
ReadLinesAsyncResult result = new ReadLinesAsyncResult(this, callback, state, true);
result.Read(caller);
return result;
}

#region no relation
internal void Close(SmtpReplyReader caller)
{
if (currentReader == caller)
{
if (readState != ReadState.Done)
{
if (byteBuffer == null)
{
byteBuffer = new byte[SmtpReplyReaderFactory.DefaultBufferSize];
}

while (0 != Read(caller, byteBuffer, 0, byteBuffer.Length)) ;
}

currentReader = null;
}
}

/* Consider removing
internal void EndClose(IAsyncResult result)
{
CloseAsyncResult.End(result);
}

internal int EndRead(IAsyncResult result)
{
return ReadAsyncResult.End(result);
}
*/

internal LineInfo[] EndReadLines(IAsyncResult result)
{
return ReadLinesAsyncResult.End(result);
}

internal LineInfo EndReadLine(IAsyncResult result)
{
LineInfo[] info = ReadLinesAsyncResult.End(result);
if (info != null && info.Length > 0)
{
return info[0];
}
return new LineInfo();
}

internal SmtpReplyReader GetNextReplyReader()
{
if (currentReader != null)
{
currentReader.Close();
}

readState = ReadState.Status0;
currentReader = new SmtpReplyReader(this);
return currentReader;
}

int ProcessRead(byte[] buffer, int offset, int read, bool readLine)
{
// if 0 bytes were read,there was a failure
if (read == 0)
{
throw new IOException(SR.GetString(SR.net_io_readfailure, SR.net_io_connectionclosed));
}

unsafe
{
fixed (byte* pBuffer = buffer)
{
byte* start = pBuffer + offset;
byte* ptr = start;
byte* end = ptr + read;

switch (readState)
{
case ReadState.Status0:
{
if (ptr < end)
{
byte b = *ptr++;
if (b < '0' && b > '9')
{
throw new FormatException(SR.GetString(SR.SmtpInvalidResponse));
}

statusCode = (SmtpStatusCode)(100 * (b - '0'));

goto case ReadState.Status1;
}
readState = ReadState.Status0;
break;
}
case ReadState.Status1:
{
if (ptr < end)
{
byte b = *ptr++;
if (b < '0' && b > '9')
{
throw new FormatException(SR.GetString(SR.SmtpInvalidResponse));
}

statusCode += 10 * (b - '0');

goto case ReadState.Status2;
}
readState = ReadState.Status1;
break;
}
case ReadState.Status2:
{
if (ptr < end)
{
byte b = *ptr++;
if (b < '0' && b > '9')
{
throw new FormatException(SR.GetString(SR.SmtpInvalidResponse));
}

statusCode += b - '0';

goto case ReadState.ContinueFlag;
}
readState = ReadState.Status2;
break;
}
case ReadState.ContinueFlag:
{
if (ptr < end)
{
byte b = *ptr++;
if (b == ' ') // last line
{
goto case ReadState.LastCR;
}
else if (b == '-') // more lines coming
{
goto case ReadState.ContinueCR;
}
else // error
{
throw new FormatException(SR.GetString(SR.SmtpInvalidResponse));
}
}
readState = ReadState.ContinueFlag;
break;
}
case ReadState.ContinueCR:
{
while (ptr < end)
{
if (*ptr++ == '\r')
{
goto case ReadState.ContinueLF;
}
}
readState = ReadState.ContinueCR;
break;
}
case ReadState.ContinueLF:
{
if (ptr < end)
{
if (*ptr++ != '\n')
{
throw new FormatException(SR.GetString(SR.SmtpInvalidResponse));
}
if (readLine)
{
readState = ReadState.Status0;
return (int)(ptr - start);
}
goto case ReadState.Status0;
}
readState = ReadState.ContinueLF;
break;
}
case ReadState.LastCR:
{
while (ptr < end)
{
if (*ptr++ == '\r')
{
goto case ReadState.LastLF;
}
}
readState = ReadState.LastCR;
break;
}
case ReadState.LastLF:
{
if (ptr < end)
{
if (*ptr++ != '\n')
{
throw new FormatException(SR.GetString(SR.SmtpInvalidResponse));
}
goto case ReadState.Done;
}
readState = ReadState.LastLF;
break;
}
case ReadState.Done:
{
int actual = (int)(ptr - start);
readState = ReadState.Done;
return actual;
}
}
return (int)(ptr - start);
}
}
}

internal int Read(SmtpReplyReader caller, byte[] buffer, int offset, int count)
{
// if we've already found the delimitter, then return 0 indicating
// end of stream.
if (count == 0 || currentReader != caller || readState == ReadState.Done)
{
return 0;
}

int read = bufferedStream.Read(buffer, offset, count);
int actual = ProcessRead(buffer, offset, read, false);
if (actual < read)
{
bufferedStream.Push(buffer, offset + actual, read - actual);
}

return actual;
}

internal LineInfo ReadLine(SmtpReplyReader caller)
{
LineInfo[] info = ReadLines(caller, true);
if (info != null && info.Length > 0)
{
return info[0];
}
return new LineInfo();
}

internal LineInfo[] ReadLines(SmtpReplyReader caller)
{
return ReadLines(caller, false);
}

internal LineInfo[] ReadLines(SmtpReplyReader caller, bool oneLine)
{
if (caller != currentReader || readState == ReadState.Done)
{
return new LineInfo[0];
}

if (byteBuffer == null)
{
byteBuffer = new byte[SmtpReplyReaderFactory.DefaultBufferSize];
}

if (charBuffer == null)
{
charBuffer = new char[SmtpReplyReaderFactory.DefaultBufferSize];
}

System.Diagnostics.Debug.Assert(readState == ReadState.Status0);

StringBuilder builder = new StringBuilder();
ArrayList lines = new ArrayList();
int statusRead = 0;

for (int start = 0, read = 0; ; )
{
if (start == read)
{
read = bufferedStream.Read(byteBuffer, 0, byteBuffer.Length);
start = 0;
}

int actual = ProcessRead(byteBuffer, start, read - start, true);

if (statusRead < 4)
{
int left = Math.Min(4 - statusRead, actual);
statusRead += left;
start += left;
actual -= left;
if (actual == 0)
{
continue;
}
}

for (int i = start; i < start + actual; i++)
{
charBuffer[i] = (char)byteBuffer[i];
}

builder.Append(charBuffer, start, actual); // skip status stuff
start += actual;

if (readState == ReadState.Status0)
{
statusRead = 0;
lines.Add(new LineInfo(statusCode, builder.ToString(0, builder.Length - 2))); // return everything except CRLF

if (oneLine)
{
bufferedStream.Push(byteBuffer, start, read - start);
return (LineInfo[])lines.ToArray(typeof(LineInfo));
}
builder = new StringBuilder();
}
else if (readState == ReadState.Done)
{
lines.Add(new LineInfo(statusCode, builder.ToString(0, builder.Length - 2))); // return everything except CRLF
bufferedStream.Push(byteBuffer, start, read - start);
return (LineInfo[])lines.ToArray(typeof(LineInfo));
}
}
}

/*
class ReadAsyncResult : LazyAsyncResult
{
byte[] buffer;
int count;
int offset;
SmtpReplyReaderFactory parent;
static AsyncCallback readCallback = new AsyncCallback(ReadCallback);
int read;

internal ReadAsyncResult(SmtpReplyReaderFactory parent, byte[] buffer, int offset, int count, AsyncCallback callback, object state) : base(null, state, callback)
{
this.parent = parent;
this.buffer = buffer;
this.offset = offset;
this.count = count;
}

internal void Read( SmtpReplyReader caller ){

// if we've already found the delimitter, then return 0 indicating
// end of stream.
if (count == 0 || parent.currentReader != caller || parent.readState == ReadState.Done)
{
InvokeCallback();
return;
}
IAsyncResult result = parent.bufferedStream.BeginRead(this.buffer, this.offset, this.count, readCallback, this);
if (!result.CompletedSynchronously)
{
return;
}
this.read = parent.bufferedStream.EndRead(result);
ProcessRead();
}

internal static int End(IAsyncResult result)
{
ReadAsyncResult thisPtr = (ReadAsyncResult)result;
thisPtr.InternalWaitForCompletion();
return thisPtr.read;
}
static void ReadCallback(IAsyncResult result)
{
if (!result.CompletedSynchronously)
{
ReadAsyncResult thisPtr = (ReadAsyncResult)result.AsyncState;
try
{
thisPtr.read = thisPtr.parent.bufferedStream.EndRead(result);
thisPtr.ProcessRead();
}
catch (Exception e)
{
thisPtr.InvokeCallback(e);
}
catch {
thisPtr.InvokeCallback(new Exception(SR.GetString(SR.net_nonClsCompliantException)));
}
}
}

void ProcessRead()
{
int actual = parent.ProcessRead(buffer, offset, read, false);
if (actual < read)
{
parent.bufferedStream.Push(buffer, offset + actual, read - actual);
}
read = actual;
InvokeCallback();
}

}
*/
#endregion

class ReadLinesAsyncResult : LazyAsyncResult
{
StringBuilder builder;
ArrayList lines;
SmtpReplyReaderFactory parent;
static AsyncCallback readCallback = new AsyncCallback(ReadCallback);
int read;
int statusRead;
bool oneLine;

internal ReadLinesAsyncResult(SmtpReplyReaderFactory parent, AsyncCallback callback, object state)
: base(null, state, callback)
{
this.parent = parent;
}

internal ReadLinesAsyncResult(SmtpReplyReaderFactory parent, AsyncCallback callback, object state, bool oneLine)
: base(null, state, callback)
{
this.oneLine = oneLine;
this.parent = parent;
}

internal void Read(SmtpReplyReader caller)
{

// if we've already found the delimitter, then return 0 indicating
// end of stream.
if (parent.currentReader != caller || parent.readState == ReadState.Done)
{
InvokeCallback();
return;
}

if (parent.byteBuffer == null)
{
parent.byteBuffer = new byte[SmtpReplyReaderFactory.DefaultBufferSize];
}

if (parent.charBuffer == null)
{
parent.charBuffer = new char[SmtpReplyReaderFactory.DefaultBufferSize];
}

System.Diagnostics.Debug.Assert(parent.readState == ReadState.Status0);

builder = new StringBuilder();
lines = new ArrayList();

Read();
}

internal static LineInfo[] End(IAsyncResult result)
{
ReadLinesAsyncResult thisPtr = (ReadLinesAsyncResult)result;
thisPtr.InternalWaitForCompletion();
return (LineInfo[])thisPtr.lines.ToArray(typeof(LineInfo));
}

void Read()
{
do
{
IAsyncResult result = parent.bufferedStream.BeginRead(parent.byteBuffer, 0, parent.byteBuffer.Length, readCallback, this);
if (!result.CompletedSynchronously)
{
return;
}
read = parent.bufferedStream.EndRead(result);
} while (ProcessRead());
}

static void ReadCallback(IAsyncResult result)
{
if (!result.CompletedSynchronously)
{
Exception exception = null;
ReadLinesAsyncResult thisPtr = (ReadLinesAsyncResult)result.AsyncState;
try
{
thisPtr.read = thisPtr.parent.bufferedStream.EndRead(result);
if (thisPtr.ProcessRead())
{
thisPtr.Read();
}
}
catch (Exception e)
{
exception = e;
}

if (exception != null)
{
thisPtr.InvokeCallback(exception);
}
}
}

bool ProcessRead()
{
if (read == 0)
{
throw new IOException(SR.GetString(SR.net_io_readfailure, SR.net_io_connectionclosed));
}

for (int start = 0; start != read; )
{
int actual = parent.ProcessRead(parent.byteBuffer, start, read - start, true);

if (statusRead < 4)
{
int left = Math.Min(4 - statusRead, actual);
statusRead += left;
start += left;
actual -= left;
if (actual == 0)
{
continue;
}
}

for (int i = start; i < start + actual; i++)
{
parent.charBuffer[i] = (char)parent.byteBuffer[i];
}

builder.Append(parent.charBuffer, start, actual); // skip status stuff
start += actual;

if (parent.readState == ReadState.Status0)
{
lines.Add(new LineInfo(parent.statusCode, builder.ToString(0, builder.Length - 2))); // return everything except CRLF
builder = new StringBuilder();
statusRead = 0;

if (oneLine)
{
parent.bufferedStream.Push(parent.byteBuffer, start, read - start);
InvokeCallback();
return false;
}
}
else if (parent.readState == ReadState.Done)
{
lines.Add(new LineInfo(parent.statusCode, builder.ToString(0, builder.Length - 2))); // return everything except CRLF
parent.bufferedStream.Push(parent.byteBuffer, start, read - start);
InvokeCallback();
return false;
}
}
return true;
}

}
}
}