[英]GetLastError() returns ERROR_BROKEN_PIPE after call to PeekNamedPipe only when using message mode
I can't figure out why this is happening... I have a Named Pipe server and client application. 我无法弄清楚为什么会发生这种情况......我有一个命名管道服务器和客户端应用程序。 Both are in read/write mode and transfer data between each other. 两者都处于读/写模式并在彼此之间传输数据。 The server has two threads, one that reads from the pipe and one that writes to it. 服务器有两个线程,一个从管道读取,另一个写入管道。 While the client is writing a bunch of messages, the server's read thread will exit because it's call to PeekNamedPipe is returning false. 当客户端正在编写一堆消息时,服务器的读取线程将退出,因为它对PeekNamedPipe的调用返回false。 The return value of GetLastError() is ERROR_BROKEN_PIPE. GetLastError()的返回值是ERROR_BROKEN_PIPE。 Neither thread in the server is closing the pipe, and the client is still writing to the pipe, so I don't understand why the pipe is "broken." 服务器中的任何线程都没有关闭管道,客户端仍在写入管道,所以我不明白为什么管道“坏了”。
If I change the server to BYTE mode, then everything works flawlessly. 如果我将服务器更改为BYTE模式,那么一切都可以完美运行。 I am really wanting to use Message mode though so my "messages" do not get grouped together. 我真的想要使用消息模式,所以我的“消息”不能组合在一起。
If I change the client to BYTE mode and the server to Message mode, it works. 如果我将客户端更改为BYTE模式并将服务器更改为消息模式,则可以正常工作。
Call to CreateNamedPipe 调用CreateNamedPipe
hPipe = CreateNamedPipe(
pszPipeName,
PIPE_ACCESS_DUPLEX | FILE_FLAG_OVERLAPPED,
PIPE_WAIT | PIPE_READMODE_MESSAGE | PIPE_TYPE_MESSAGE,
PIPE_UNLIMITED_INSTANCES,
dwOutBufferSize,
dwInBufferSize,
0,
NULL);
Call to PeekNamedPipe 致电PeekNamedPipe
while( RunningState == DDCMP_STATE_RUNNING )
{
if( !PeekNamedPipe(hPipe,NULL,NULL,NULL,&dwBytesAvailable,NULL) || !dwBytesAvailable )
if( GetLastError() == ERROR_BROKEN_PIPE || GetLastError() == ERROR_PIPE_NOT_CONNECTED || GetLastError() == ERROR_INVALID_HANDLE )
break;
else
{
Sleep( 100 );
continue;
}
//call to ReadFile(hPipe,...) with dwBytesAvailable as size, and then processing of data
}
You are calling GetLastError()
not only when PeekNamedPipe()
fails, but also when it succeeds and returns 0 bytes. 您不仅在PeekNamedPipe()
失败时调用GetLastError()
,而且在成功并返回0字节时调用GetLastError()
。 You should not be calling GetLastError()
in that latter case, as the value will not be meaningful. 在后一种情况下,您不应该调用GetLastError()
,因为该值没有意义。 Use it more like this instead: 使用它更像这样:
while( RunningState == DDCMP_STATE_RUNNING )
{
if( !PeekNamedPipe(hPipe, NULL, NULL, NULL, &dwBytesAvailable, NULL) )
{
DWORD dwError = GetLastError();
if( (dwError == ERROR_BROKEN_PIPE) ||
(dwError == ERROR_PIPE_NOT_CONNECTED) ||
(dwError == ERROR_INVALID_HANDLE) )
{
break;
}
dwBytesAvailable = 0;
}
if( !dwBytesAvailable )
{
Sleep(100);
continue;
}
//call to ReadFile(hPipe,...) with dwBytesAvailable as size, and then processing of data
}
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