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On win32, retry reading when WSARecv returns WSAEWOULDBLOCK. There seem

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to be cases when at least Windows 2000 can do this even though select
just indicated that the socket is readable.

Per report and analysis from Cyril VELTER.
This commit is contained in:
Magnus Hagander 2007-06-04 13:39:28 +00:00
parent 0e92f9813e
commit aae5403278
1 changed files with 30 additions and 10 deletions
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40
src/backend/port/win32/socket.c
View File

@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/port/win32/socket.c,v 1.17 2007/01/26 20:06:52 tgl Exp $
* $PostgreSQL: pgsql/src/backend/port/win32/socket.c,v 1.18 2007/06/04 13:39:28 mha Exp $
*
*-------------------------------------------------------------------------
*/
@ -291,6 +291,7 @@ pgwin32_recv(SOCKET s, char *buf, int len, int f)
int r;
DWORD b;
DWORD flags = f;
int n;
if (pgwin32_poll_signals())
return -1;
@ -312,17 +313,36 @@ pgwin32_recv(SOCKET s, char *buf, int len, int f)
/* No error, zero bytes (win2000+) or error+WSAEWOULDBLOCK (<=nt4) */
if (pgwin32_waitforsinglesocket(s, FD_READ | FD_CLOSE | FD_ACCEPT,
INFINITE) == 0)
return -1;
r = WSARecv(s, &wbuf, 1, &b, &flags, NULL, NULL);
if (r == SOCKET_ERROR)
for (n = 0; n < 5; n++)
{
TranslateSocketError();
return -1;
if (pgwin32_waitforsinglesocket(s, FD_READ | FD_CLOSE | FD_ACCEPT,
INFINITE) == 0)
return -1; /* errno already set */
r = WSARecv(s, &wbuf, 1, &b, &flags, NULL, NULL);
if (r == SOCKET_ERROR)
{
if (WSAGetLastError() == WSAEWOULDBLOCK)
{
/*
* There seem to be cases on win2k (at least) where WSARecv
* can return WSAEWOULDBLOCK even when pgwin32_waitforsinglesocket
* claims the socket is readable. In this case, just sleep for a
* moment and try again. We try up to 5 times - if it fails more than
* that it's not likely to ever come back.
*/
pg_usleep(10000);
continue;
}
TranslateSocketError();
return -1;
}
return b;
}
return b;
ereport(NOTICE,
(errmsg_internal("Failed to read from ready socket (after retries)")));
errno = EWOULDBLOCK;
return -1;
}
int