cpython/Modules/_multiprocessing/pipe_connection.c at 2.7 · python/cpython · GitHub

Name: cpython/Modules/_multiprocessing/pipe_connection.c at 2.7 · python/cpython · GitHub
Rating: 4.4 (5003 reviews)
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/*
 * A type which wraps a pipe handle in message oriented mode
 *
 * pipe_connection.c
 *
 * Copyright (c) 2006-2008, R Oudkerk --- see COPYING.txt
 */

#include"multiprocessing.h"

#defineCLOSE(h) CloseHandle(h)

/*
 * Send string to the pipe; assumes in message oriented mode
 */

staticPy_ssize_t
conn_send_string(ConnectionObject*conn, char*string, size_tlength)
{
DWORDamount_written;
BOOLret;

Py_BEGIN_ALLOW_THREADS
ret=WriteFile(conn->handle, string, length, &amount_written, NULL);
Py_END_ALLOW_THREADS

if (ret==0&&GetLastError() ==ERROR_NO_SYSTEM_RESOURCES) {
PyErr_Format(PyExc_ValueError, "Cannnot send %"PY_FORMAT_SIZE_T"d bytes over connection", length);
returnMP_STANDARD_ERROR;
 }

returnret ? MP_SUCCESS : MP_STANDARD_ERROR;
}

/*
 * Attempts to read into buffer, or if buffer too small into *newbuffer.
 *
 * Returns number of bytes read. Assumes in message oriented mode.
 */

staticPy_ssize_t
conn_recv_string(ConnectionObject*conn, char*buffer,
size_tbuflength, char**newbuffer, size_tmaxlength)
{
DWORDleft, length, full_length, err;
BOOLret;
*newbuffer=NULL;

Py_BEGIN_ALLOW_THREADS
ret=ReadFile(conn->handle, buffer, MIN(buflength, maxlength),
&length, NULL);
Py_END_ALLOW_THREADS
if (ret)
returnlength;

err=GetLastError();
if (err!=ERROR_MORE_DATA) {
if (err==ERROR_BROKEN_PIPE)
returnMP_END_OF_FILE;
returnMP_STANDARD_ERROR;
 }

if (!PeekNamedPipe(conn->handle, NULL, 0, NULL, NULL, &left))
returnMP_STANDARD_ERROR;

full_length=length+left;
if (full_length>maxlength)
returnMP_BAD_MESSAGE_LENGTH;

*newbuffer=PyMem_Malloc(full_length);
if (*newbuffer==NULL)
returnMP_MEMORY_ERROR;

memcpy(*newbuffer, buffer, length);

Py_BEGIN_ALLOW_THREADS
ret=ReadFile(conn->handle, *newbuffer+length, left, &length, NULL);
Py_END_ALLOW_THREADS
if (ret) {
assert(length==left);
returnfull_length;
 } else {
PyMem_Free(*newbuffer);
returnMP_STANDARD_ERROR;
 }
}

/*
 * Check whether any data is available for reading
 */

staticint
conn_poll(ConnectionObject*conn, doubletimeout, PyThreadState*_save)
{
DWORDbytes, deadline, delay;
intdifference, res;
BOOLblock= FALSE;

if (!PeekNamedPipe(conn->handle, NULL, 0, NULL, &bytes, NULL))
returnMP_STANDARD_ERROR;

if (timeout==0.0)
returnbytes>0;

if (timeout<0.0)
block= TRUE;
else
/* XXX does not check for overflow */
deadline=GetTickCount() + (DWORD)(1000*timeout+0.5);

Sleep(0);

for (delay=1 ; ; delay+=1) {
if (!PeekNamedPipe(conn->handle, NULL, 0, NULL, &bytes, NULL))
returnMP_STANDARD_ERROR;
elseif (bytes>0)
return TRUE;

if (!block) {
difference=deadline-GetTickCount();
if (difference<0)
return FALSE;
if ((int)delay>difference)
delay=difference;
 }

if (delay>20)
delay=20;

Sleep(delay);

/* check for signals */
Py_BLOCK_THREADS
res=PyErr_CheckSignals();
Py_UNBLOCK_THREADS

if (res)
returnMP_EXCEPTION_HAS_BEEN_SET;
 }
}

/*
 * "connection.h" defines the PipeConnection type using the definitions above
 */

#defineCONNECTION_NAME "PipeConnection"
#defineCONNECTION_TYPE PipeConnectionType

#include"connection.h"