2004-02-10 04:42:45 +01:00
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/*-------------------------------------------------------------------------
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*
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* pgsleep.c
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* Portable delay handling.
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*
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*
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2018-01-03 05:30:12 +01:00
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* Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
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2004-02-10 04:42:45 +01:00
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*
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2010-09-20 22:08:53 +02:00
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* src/port/pgsleep.c
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2004-02-10 04:42:45 +01:00
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*
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*-------------------------------------------------------------------------
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*/
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2004-06-24 20:53:48 +02:00
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#include "c.h"
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2004-02-10 04:42:45 +01:00
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2004-02-10 05:23:03 +01:00
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#include <unistd.h>
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2004-02-10 04:42:45 +01:00
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#include <sys/time.h>
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2016-09-27 06:05:21 +02:00
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#ifdef HAVE_SYS_SELECT_H
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#include <sys/select.h>
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#endif
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2004-02-10 04:42:45 +01:00
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2006-07-16 22:17:04 +02:00
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/*
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* In a Windows backend, we don't use this implementation, but rather
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* the signal-aware version in src/backend/port/win32/signal.c.
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*/
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#if defined(FRONTEND) || !defined(WIN32)
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2004-02-10 04:42:45 +01:00
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/*
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* pg_usleep --- delay the specified number of microseconds.
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*
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* NOTE: although the delay is specified in microseconds, the effective
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* resolution is only 1/HZ, or 10 milliseconds, on most Unixen. Expect
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* the requested delay to be rounded up to the next resolution boundary.
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*
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* On machines where "long" is 32 bits, the maximum delay is ~2000 seconds.
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2013-06-23 20:43:10 +02:00
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*
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* CAUTION: the behavior when a signal arrives during the sleep is platform
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* dependent. On most Unix-ish platforms, a signal does not terminate the
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* sleep; but on some, it will (the Windows implementation also allows signals
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* to terminate pg_usleep). And there are platforms where not only does a
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* signal not terminate the sleep, but it actually resets the timeout counter
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* so that the sleep effectively starts over! It is therefore rather hazardous
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* to use this for long sleeps; a continuing stream of signal events could
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* prevent the sleep from ever terminating. Better practice for long sleeps
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* is to use WaitLatch() with a timeout.
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2004-02-10 04:42:45 +01:00
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*/
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void
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pg_usleep(long microsec)
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{
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if (microsec > 0)
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{
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#ifndef WIN32
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struct timeval delay;
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delay.tv_sec = microsec / 1000000L;
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delay.tv_usec = microsec % 1000000L;
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(void) select(0, NULL, NULL, NULL, &delay);
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#else
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Here's an attempt at new socket and signal code for win32.
It works on the principle of turning sockets into non-blocking, and then
emulate blocking behaviour on top of that, while allowing signals to
run. Signals are now implemented using an event instead of APCs, thus
getting rid of the issue of APCs not being compatible with "old style"
sockets functions.
It also moves the win32 specific code away from pqsignal.h/c into
port/win32, and also removes the "thread style workaround" of the APC
issue previously in place.
In order to make things work, a few things are also changed in pgstat.c:
1) There is now a separate pipe to the collector and the bufferer. This
is required because the pipe will otherwise only be signalled in one of
the processes when the postmaster goes down. The MS winsock code for
select() must have some kind of workaround for this behaviour, but I
have found no stable way of doing that. You really are not supposed to
use the same socket from more than one process (unless you use
WSADuplicateSocket(), in which case the docs specifically say that only
one will be flagged).
2) The check for "postmaster death" is moved into a separate select()
call after the main loop. The previous behaviour select():ed on the
postmaster pipe, while later explicitly saying "we do NOT check for
postmaster exit inside the loop".
The issue was that the code relies on the same select() call seeing both
the postmaster pipe *and* the pgstat pipe go away. This does not always
happen, and it appears that useing WSAEventSelect() makes it even more
common that it does not.
Since it's only called when the process exits, I don't think using a
separate select() call will have any significant impact on how the stats
collector works.
Magnus Hagander
2004-04-12 18:19:18 +02:00
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SleepEx((microsec < 500 ? 1 : (microsec + 500) / 1000), FALSE);
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2004-02-10 04:42:45 +01:00
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#endif
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}
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}
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2006-07-16 22:17:04 +02:00
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Phase 2 of pgindent updates.
Change pg_bsd_indent to follow upstream rules for placement of comments
to the right of code, and remove pgindent hack that caused comments
following #endif to not obey the general rule.
Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using
the published version of pg_bsd_indent, but a hacked-up version that
tried to minimize the amount of movement of comments to the right of
code. The situation of interest is where such a comment has to be
moved to the right of its default placement at column 33 because there's
code there. BSD indent has always moved right in units of tab stops
in such cases --- but in the previous incarnation, indent was working
in 8-space tab stops, while now it knows we use 4-space tabs. So the
net result is that in about half the cases, such comments are placed
one tab stop left of before. This is better all around: it leaves
more room on the line for comment text, and it means that in such
cases the comment uniformly starts at the next 4-space tab stop after
the code, rather than sometimes one and sometimes two tabs after.
Also, ensure that comments following #endif are indented the same
as comments following other preprocessor commands such as #else.
That inconsistency turns out to have been self-inflicted damage
from a poorly-thought-through post-indent "fixup" in pgindent.
This patch is much less interesting than the first round of indent
changes, but also bulkier, so I thought it best to separate the effects.
Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org
Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
2017-06-21 21:18:54 +02:00
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#endif /* defined(FRONTEND) || !defined(WIN32) */
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