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Commitede5072

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committed
Change ps_status.c to explicitly track the current logical length of ps_buffer.
This saves cycles in get_ps_display() on many popular platforms, and moreimportantly ensures that get_ps_display() will correctly return an emptystring if init_ps_display() hasn't been called yet. Per trouble reportfrom Ray Stell, in which log_line_prefix %i produced junk early in backendstartup.Back-patch to 8.0. 7.4 doesn't have %i and its version of get_ps_display()makes no pretense of avoiding pad junk anyhow.
1 parent2175d4f commitede5072

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1 file changed

+18
-28
lines changed

1 file changed

+18
-28
lines changed

‎src/backend/utils/misc/ps_status.c‎

Lines changed: 18 additions & 28 deletions
Original file line numberDiff line numberDiff line change
@@ -5,7 +5,7 @@
55
* to contain some useful information. Mechanism differs wildly across
66
* platforms.
77
*
8-
* $PostgreSQL: pgsql/src/backend/utils/misc/ps_status.c,v 1.40 2010/01/02 16:57:58 momjian Exp $
8+
* $PostgreSQL: pgsql/src/backend/utils/misc/ps_status.c,v 1.41 2010/05/27 19:19:38 tgl Exp $
99
*
1010
* Copyright (c) 2000-2010, PostgreSQL Global Development Group
1111
* various details abducted from various places
@@ -51,7 +51,7 @@ boolupdate_process_title = true;
5151
* (some other BSD systems)
5252
* PS_USE_CLOBBER_ARGV
5353
* write over the argv and environment area
54-
* (most SysV-like systems)
54+
* (Linux andmost SysV-like systems)
5555
* PS_USE_WIN32
5656
* push the string out as the name of a Windows event
5757
* PS_USE_NONE
@@ -84,7 +84,7 @@ boolupdate_process_title = true;
8484

8585

8686
#ifndefPS_USE_CLOBBER_ARGV
87-
/* all but oneoptions need a buffer to write their ps line in */
87+
/* all but oneoption need a buffer to write their ps line in */
8888
#definePS_BUFFER_SIZE 256
8989
staticcharps_buffer[PS_BUFFER_SIZE];
9090
staticconstsize_tps_buffer_size=PS_BUFFER_SIZE;
@@ -94,6 +94,8 @@ static size_t ps_buffer_size;/* space determined at run time */
9494
staticsize_tlast_status_len;/* use to minimize length of clobber */
9595
#endif/* PS_USE_CLOBBER_ARGV */
9696

97+
staticsize_tps_buffer_cur_len;/* nominal strlen(ps_buffer) */
98+
9799
staticsize_tps_buffer_fixed_size;/* size of the constant prefix */
98100

99101
/* save the original argv[] location here */
@@ -226,6 +228,7 @@ init_ps_display(const char *username, const char *dbname,
226228
/* no ps display if you didn't call save_ps_display_args() */
227229
if (!save_argv)
228230
return;
231+
229232
#ifdefPS_USE_CLOBBER_ARGV
230233
/* If ps_buffer is a pointer, it might still be null */
231234
if (!ps_buffer)
@@ -270,7 +273,7 @@ init_ps_display(const char *username, const char *dbname,
270273
username,dbname,host_info);
271274
#endif
272275

273-
ps_buffer_fixed_size=strlen(ps_buffer);
276+
ps_buffer_cur_len=ps_buffer_fixed_size=strlen(ps_buffer);
274277

275278
set_ps_display(initial_str, true);
276279
#endif/* not PS_USE_NONE */
@@ -285,11 +288,11 @@ init_ps_display(const char *username, const char *dbname,
285288
void
286289
set_ps_display(constchar*activity,boolforce)
287290
{
288-
291+
#ifndefPS_USE_NONE
292+
/* update_process_title=off disables updates, unless force = true */
289293
if (!force&& !update_process_title)
290294
return;
291295

292-
#ifndefPS_USE_NONE
293296
/* no ps display for stand-alone backend */
294297
if (!IsUnderPostmaster)
295298
return;
@@ -303,6 +306,7 @@ set_ps_display(const char *activity, bool force)
303306
/* Update ps_buffer to contain both fixed part and activity */
304307
strlcpy(ps_buffer+ps_buffer_fixed_size,activity,
305308
ps_buffer_size-ps_buffer_fixed_size);
309+
ps_buffer_cur_len=strlen(ps_buffer);
306310

307311
/* Transmit new setting to kernel, if necessary */
308312

@@ -315,7 +319,7 @@ set_ps_display(const char *activity, bool force)
315319
unionpstunpst;
316320

317321
pst.pst_command=ps_buffer;
318-
pstat(PSTAT_SETCMD,pst,strlen(ps_buffer),0,0);
322+
pstat(PSTAT_SETCMD,pst,ps_buffer_cur_len,0,0);
319323
}
320324
#endif/* PS_USE_PSTAT */
321325

@@ -325,16 +329,11 @@ set_ps_display(const char *activity, bool force)
325329
#endif/* PS_USE_PS_STRINGS */
326330

327331
#ifdefPS_USE_CLOBBER_ARGV
328-
{
329-
intbuflen;
330-
331-
/* pad unused memory */
332-
buflen=strlen(ps_buffer);
333-
/* clobber remainder of old status string */
334-
if (last_status_len>buflen)
335-
MemSet(ps_buffer+buflen,PS_PADDING,last_status_len-buflen);
336-
last_status_len=buflen;
337-
}
332+
/* pad unused memory; need only clobber remainder of old status string */
333+
if (last_status_len>ps_buffer_cur_len)
334+
MemSet(ps_buffer+ps_buffer_cur_len,PS_PADDING,
335+
last_status_len-ps_buffer_cur_len);
336+
last_status_len=ps_buffer_cur_len;
338337
#endif/* PS_USE_CLOBBER_ARGV */
339338

340339
#ifdefPS_USE_WIN32
@@ -369,24 +368,15 @@ const char *
369368
get_ps_display(int*displen)
370369
{
371370
#ifdefPS_USE_CLOBBER_ARGV
372-
size_toffset;
373-
374371
/* If ps_buffer is a pointer, it might still be null */
375372
if (!ps_buffer)
376373
{
377374
*displen=0;
378375
return"";
379376
}
380-
381-
/* Remove any trailing spaces to offset the effect of PS_PADDING */
382-
offset=ps_buffer_size;
383-
while (offset>ps_buffer_fixed_size&&ps_buffer[offset-1]==PS_PADDING)
384-
offset--;
385-
386-
*displen=offset-ps_buffer_fixed_size;
387-
#else
388-
*displen=strlen(ps_buffer+ps_buffer_fixed_size);
389377
#endif
390378

379+
*displen= (int) (ps_buffer_cur_len-ps_buffer_fixed_size);
380+
391381
returnps_buffer+ps_buffer_fixed_size;
392382
}

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