Check for EOF in NamedPipeClientStream
With C functions it is possible to check if t开发者_运维技巧he output side of a pipe is empty via _eof(pipeOut)
and skip the read operation.
int endOfFile = _eof(myPipeIn);
if(endOfFile != 0)
int aReadCount = _read(myPipeIn, aBufferPtr, 256);
Is it possible to do something similar with .Net's NamedPipeClientStream?
Unfortunately Bueller's hint did not work for me, because ReadLine
can block.
But with Zach's answer on Alternative to StreamReader.Peek and Thread.Interrupt I came up with the following:
[DllImport("kernel32.dll", SetLastError = true)]
static extern bool PeekNamedPipe(SafeHandle handle,
byte[] buffer, uint nBufferSize, ref uint bytesRead,
ref uint bytesAvail, ref uint BytesLeftThisMessage);
static bool SomethingToRead(SafeHandle streamHandle)
{
byte[] aPeekBuffer = new byte[1];
uint aPeekedBytes = 0;
uint aAvailBytes = 0;
uint aLeftBytes = 0;
bool aPeekedSuccess = PeekNamedPipe(
streamHandle,
aPeekBuffer, 1,
ref aPeekedBytes, ref aAvailBytes, ref aLeftBytes);
if (aPeekedSuccess && aPeekBuffer[0] != 0)
return true;
else
return false;
}
In my case the additional P/Invoke call is no problem.
According to the documentation http://msdn.microsoft.com/en-us/library/system.io.pipes.namedpipeclientstream.aspx there isn't a "peek" type of capability available on .Net pipes.
The methodology identified is to test the result of the read operation for NULL.
using (StreamReader sr = new StreamReader(pipeClient))
{
// Display the read text to the console
string temp;
while ((temp = sr.ReadLine()) != null)
{
Console.WriteLine("Received from server: {0}", temp);
}
}
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