12d17deb4f
machines. I have just been observing some scenarios where set_ps_display accounts for more than 10% of the backend CPU, and this loop has to be the reason.
294 lines
7.0 KiB
C
294 lines
7.0 KiB
C
/*--------------------------------------------------------------------
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* ps_status.c
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*
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* Routines to support changing the ps display of PostgreSQL backends
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* to contain some useful information. Mechanism differs wildly across
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* platforms.
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*
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* $Header: /cvsroot/pgsql/src/backend/utils/misc/ps_status.c,v 1.12 2001/12/21 15:22:09 tgl Exp $
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*
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* Copyright 2000 by PostgreSQL Global Development Group
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* various details abducted from various places
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*--------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <unistd.h>
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#ifdef HAVE_SYS_PSTAT_H
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#include <sys/pstat.h> /* for HP-UX */
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#endif
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#ifdef HAVE_PS_STRINGS
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#include <machine/vmparam.h> /* for old BSD */
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#include <sys/exec.h>
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#endif
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#include "miscadmin.h"
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#include "utils/ps_status.h"
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extern char **environ;
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/*------
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* Alternative ways of updating ps display:
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*
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* PS_USE_SETPROCTITLE
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* use the function setproctitle(const char *, ...)
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* (newer BSD systems)
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* PS_USE_PSTAT
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* use the pstat(PSTAT_SETCMD, )
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* (HPUX)
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* PS_USE_PS_STRINGS
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* assign PS_STRINGS->ps_argvstr = "string"
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* (some BSD systems)
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* PS_USE_CHANGE_ARGV
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* assign argv[0] = "string"
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* (some other BSD systems)
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* PS_USE_CLOBBER_ARGV
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* write over the argv and environment area
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* (most SysV-like systems)
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* PS_USE_NONE
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* don't update ps display
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* (This is the default, as it is safest.)
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*/
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#if defined(HAVE_SETPROCTITLE)
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#define PS_USE_SETPROCTITLE
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#elif defined(HAVE_PSTAT) && defined(PSTAT_SETCMD)
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#define PS_USE_PSTAT
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#elif defined(HAVE_PS_STRINGS)
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#define PS_USE_PS_STRINGS
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#elif defined(BSD) || defined(__bsdi__) || defined(__hurd__)
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#define PS_USE_CHANGE_ARGV
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#elif defined(__linux__) || defined(_AIX) || defined(__sgi) || (defined(sun) && !defined(BSD)) || defined(ultrix) || defined(__ksr__) || defined(__osf__) || defined(__QNX__) || defined(__svr4__) || defined(__svr5__) || defined(__darwin__)
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#define PS_USE_CLOBBER_ARGV
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#else
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#define PS_USE_NONE
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#endif
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/* Different systems want the buffer padded differently */
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#if defined(_AIX) || defined(__linux__) || defined(__QNX__) || defined(__svr4__)
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#define PS_PADDING '\0'
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#else
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#define PS_PADDING ' '
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#endif
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#ifndef PS_USE_CLOBBER_ARGV
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/* all but one options need a buffer to write their ps line in */
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#define PS_BUFFER_SIZE 256
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static char ps_buffer[PS_BUFFER_SIZE];
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static const size_t ps_buffer_size = PS_BUFFER_SIZE;
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#else /* PS_USE_CLOBBER_ARGV */
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static char *ps_buffer; /* will point to argv area */
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static size_t ps_buffer_size; /* space determined at run time */
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#endif /* PS_USE_CLOBBER_ARGV */
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static size_t ps_buffer_fixed_size; /* size of the constant prefix */
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/* save the original argv[] location here */
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static int save_argc;
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static char **save_argv;
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/*
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* Call this early in startup to save the original argc/argv values.
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*
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* argv[] will not be overwritten by this routine, but may be overwritten
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* during init_ps_display. Also, the physical location of the environment
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* strings may be moved, so this should be called before any code that
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* might try to hang onto a getenv() result.
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*/
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void
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save_ps_display_args(int argc, char *argv[])
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{
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save_argc = argc;
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save_argv = argv;
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#ifdef PS_USE_CLOBBER_ARGV
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/*
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* If we're going to overwrite the argv area, count the available
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* space. Also move the environment to make additional room.
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*/
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{
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char *end_of_area = NULL;
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char **new_environ;
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int i;
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/*
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* check for contiguous argv strings
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*/
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for (i = 0; i < argc; i++)
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{
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if (i == 0 || end_of_area + 1 == argv[i])
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end_of_area = argv[i] + strlen(argv[i]);
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}
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if (end_of_area == NULL) /* probably can't happen? */
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{
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ps_buffer = NULL;
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ps_buffer_size = 0;
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return;
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}
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/*
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* check for contiguous environ strings following argv
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*/
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for (i = 0; environ[i] != NULL; i++)
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{
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if (end_of_area + 1 == environ[i])
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end_of_area = environ[i] + strlen(environ[i]);
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}
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ps_buffer = argv[0];
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ps_buffer_size = end_of_area - argv[0] - 1;
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/*
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* move the environment out of the way
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*/
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new_environ = malloc(sizeof(char *) * (i + 1));
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for (i = 0; environ[i] != NULL; i++)
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new_environ[i] = strdup(environ[i]);
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new_environ[i] = NULL;
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environ = new_environ;
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}
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#endif /* PS_USE_CLOBBER_ARGV */
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}
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/*
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* Call this once during subprocess startup to set the identification
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* values. At this point, the original argv[] array may be overwritten.
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*/
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void
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init_ps_display(const char *username, const char *dbname,
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const char *host_info)
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{
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Assert(username);
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Assert(dbname);
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Assert(host_info);
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#ifndef PS_USE_NONE
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/* no ps display for stand-alone backend */
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if (!IsUnderPostmaster)
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return;
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/* no ps display if you didn't call save_ps_display_args() */
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if (!save_argv)
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return;
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#ifdef PS_USE_CLOBBER_ARGV
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/* If ps_buffer is a pointer, it might still be null */
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if (!ps_buffer)
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return;
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#endif
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/*
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* Overwrite argv[] to point at appropriate space, if needed
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*/
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#ifdef PS_USE_CHANGE_ARGV
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save_argv[0] = ps_buffer;
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save_argv[1] = NULL;
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#endif /* PS_USE_CHANGE_ARGV */
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#ifdef PS_USE_CLOBBER_ARGV
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save_argv[1] = NULL;
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#endif /* PS_USE_CLOBBER_ARGV */
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/*
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* Make fixed prefix of ps display.
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*/
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#ifdef PS_USE_SETPROCTITLE
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/*
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* apparently setproctitle() already adds a `progname:' prefix to the
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* ps line
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*/
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snprintf(ps_buffer, ps_buffer_size,
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"%s %s %s ",
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username, dbname, host_info);
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#else
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snprintf(ps_buffer, ps_buffer_size,
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"postgres: %s %s %s ",
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username, dbname, host_info);
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#endif
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ps_buffer_fixed_size = strlen(ps_buffer);
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#endif /* not PS_USE_NONE */
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}
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/*
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* Call this to update the ps status display to a fixed prefix plus an
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* indication of what you're currently doing passed in the argument.
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*/
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void
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set_ps_display(const char *activity)
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{
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#ifndef PS_USE_NONE
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/* no ps display for stand-alone backend */
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if (!IsUnderPostmaster)
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return;
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#ifdef PS_USE_CLOBBER_ARGV
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/* If ps_buffer is a pointer, it might still be null */
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if (!ps_buffer)
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return;
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#endif
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/* Update ps_buffer to contain both fixed part and activity */
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StrNCpy(ps_buffer + ps_buffer_fixed_size, activity,
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ps_buffer_size - ps_buffer_fixed_size);
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/* Transmit new setting to kernel, if necessary */
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#ifdef PS_USE_SETPROCTITLE
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setproctitle("%s", ps_buffer);
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#endif
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#ifdef PS_USE_PSTAT
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{
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union pstun pst;
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pst.pst_command = ps_buffer;
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pstat(PSTAT_SETCMD, pst, strlen(ps_buffer), 0, 0);
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}
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#endif /* PS_USE_PSTAT */
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#ifdef PS_USE_PS_STRINGS
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PS_STRINGS->ps_nargvstr = 1;
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PS_STRINGS->ps_argvstr = ps_buffer;
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#endif /* PS_USE_PS_STRINGS */
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#ifdef PS_USE_CLOBBER_ARGV
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{
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int buflen;
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/* pad unused memory */
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buflen = strlen(ps_buffer);
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MemSet(ps_buffer + buflen, PS_PADDING, ps_buffer_size - buflen);
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}
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#endif /* PS_USE_CLOBBER_ARGV */
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#endif /* not PS_USE_NONE */
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}
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/*
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* Returns what's currently in the ps display, in case someone needs
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* it. Note that only the activity part is returned.
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*/
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const char *
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get_ps_display(void)
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{
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#ifdef PS_USE_CLOBBER_ARGV
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/* If ps_buffer is a pointer, it might still be null */
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if (!ps_buffer)
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return "";
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#endif
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return ps_buffer + ps_buffer_fixed_size;
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}
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