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-rw-r--r--src/backend/postmaster/pgstat.c63
-rw-r--r--src/backend/utils/adt/pgstatfuncs.c17
-rw-r--r--src/include/pgstat.h12
3 files changed, 72 insertions, 20 deletions
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index accf302cf73..1ffdac5448d 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -2701,7 +2701,7 @@ CreateSharedBackendStatus(void)
buffer = BackendActivityBuffer;
for (i = 0; i < NumBackendStatSlots; i++)
{
- BackendStatusArray[i].st_activity = buffer;
+ BackendStatusArray[i].st_activity_raw = buffer;
buffer += pgstat_track_activity_query_size;
}
}
@@ -2922,11 +2922,11 @@ pgstat_bestart(void)
#endif
beentry->st_state = STATE_UNDEFINED;
beentry->st_appname[0] = '\0';
- beentry->st_activity[0] = '\0';
+ beentry->st_activity_raw[0] = '\0';
/* Also make sure the last byte in each string area is always 0 */
beentry->st_clienthostname[NAMEDATALEN - 1] = '\0';
beentry->st_appname[NAMEDATALEN - 1] = '\0';
- beentry->st_activity[pgstat_track_activity_query_size - 1] = '\0';
+ beentry->st_activity_raw[pgstat_track_activity_query_size - 1] = '\0';
beentry->st_progress_command = PROGRESS_COMMAND_INVALID;
beentry->st_progress_command_target = InvalidOid;
@@ -3017,7 +3017,7 @@ pgstat_report_activity(BackendState state, const char *cmd_str)
pgstat_increment_changecount_before(beentry);
beentry->st_state = STATE_DISABLED;
beentry->st_state_start_timestamp = 0;
- beentry->st_activity[0] = '\0';
+ beentry->st_activity_raw[0] = '\0';
beentry->st_activity_start_timestamp = 0;
/* st_xact_start_timestamp and wait_event_info are also disabled */
beentry->st_xact_start_timestamp = 0;
@@ -3034,8 +3034,12 @@ pgstat_report_activity(BackendState state, const char *cmd_str)
start_timestamp = GetCurrentStatementStartTimestamp();
if (cmd_str != NULL)
{
- len = pg_mbcliplen(cmd_str, strlen(cmd_str),
- pgstat_track_activity_query_size - 1);
+ /*
+ * Compute length of to-be-stored string unaware of multi-byte
+ * characters. For speed reasons that'll get corrected on read, rather
+ * than computed every write.
+ */
+ len = Min(strlen(cmd_str), pgstat_track_activity_query_size - 1);
}
current_timestamp = GetCurrentTimestamp();
@@ -3049,8 +3053,8 @@ pgstat_report_activity(BackendState state, const char *cmd_str)
if (cmd_str != NULL)
{
- memcpy((char *) beentry->st_activity, cmd_str, len);
- beentry->st_activity[len] = '\0';
+ memcpy((char *) beentry->st_activity_raw, cmd_str, len);
+ beentry->st_activity_raw[len] = '\0';
beentry->st_activity_start_timestamp = start_timestamp;
}
@@ -3278,8 +3282,8 @@ pgstat_read_current_status(void)
*/
strcpy(localappname, (char *) beentry->st_appname);
localentry->backendStatus.st_appname = localappname;
- strcpy(localactivity, (char *) beentry->st_activity);
- localentry->backendStatus.st_activity = localactivity;
+ strcpy(localactivity, (char *) beentry->st_activity_raw);
+ localentry->backendStatus.st_activity_raw = localactivity;
localentry->backendStatus.st_ssl = beentry->st_ssl;
#ifdef USE_SSL
if (beentry->st_ssl)
@@ -3945,10 +3949,13 @@ pgstat_get_backend_current_activity(int pid, bool checkUser)
/* Now it is safe to use the non-volatile pointer */
if (checkUser && !superuser() && beentry->st_userid != GetUserId())
return "<insufficient privilege>";
- else if (*(beentry->st_activity) == '\0')
+ else if (*(beentry->st_activity_raw) == '\0')
return "<command string not enabled>";
else
- return beentry->st_activity;
+ {
+ /* this'll leak a bit of memory, but that seems acceptable */
+ return pgstat_clip_activity(beentry->st_activity_raw);
+ }
}
beentry++;
@@ -3994,7 +4001,7 @@ pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
if (beentry->st_procpid == pid)
{
/* Read pointer just once, so it can't change after validation */
- const char *activity = beentry->st_activity;
+ const char *activity = beentry->st_activity_raw;
const char *activity_last;
/*
@@ -4017,7 +4024,8 @@ pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
/*
* Copy only ASCII-safe characters so we don't run into encoding
* problems when reporting the message; and be sure not to run off
- * the end of memory.
+ * the end of memory. As only ASCII characters are reported, it
+ * doesn't seem necessary to perform multibyte aware clipping.
*/
ascii_safe_strlcpy(buffer, activity,
Min(buflen, pgstat_track_activity_query_size));
@@ -6270,3 +6278,30 @@ pgstat_db_requested(Oid databaseid)
return false;
}
+
+/*
+ * Convert a potentially unsafely truncated activity string (see
+ * PgBackendStatus.st_activity_raw's documentation) into a correctly truncated
+ * one.
+ *
+ * The returned string is allocated in the caller's memory context and may be
+ * freed.
+ */
+char *
+pgstat_clip_activity(const char *activity)
+{
+ int rawlen = strnlen(activity, pgstat_track_activity_query_size - 1);
+ int cliplen;
+
+ /*
+ * All supported server-encodings make it possible to determine the length
+ * of a multi-byte character from its first byte (this is not the case for
+ * client encodings, see GB18030). As st_activity is always stored using
+ * server encoding, this allows us to perform multi-byte aware truncation,
+ * even if the string earlier was truncated in the middle of a multi-byte
+ * character.
+ */
+ cliplen = pg_mbcliplen(activity, rawlen,
+ pgstat_track_activity_query_size - 1);
+ return pnstrdup(activity, cliplen);
+}
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 20ce48b2d82..5a968e3758f 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -664,6 +664,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
is_member_of_role(GetUserId(), DEFAULT_ROLE_READ_ALL_STATS))
{
SockAddr zero_clientaddr;
+ char *clipped_activity;
switch (beentry->st_state)
{
@@ -690,7 +691,9 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
break;
}
- values[5] = CStringGetTextDatum(beentry->st_activity);
+ clipped_activity = pgstat_clip_activity(beentry->st_activity_raw);
+ values[5] = CStringGetTextDatum(clipped_activity);
+ pfree(clipped_activity);
proc = BackendPidGetProc(beentry->st_procpid);
if (proc != NULL)
@@ -906,17 +909,23 @@ pg_stat_get_backend_activity(PG_FUNCTION_ARGS)
int32 beid = PG_GETARG_INT32(0);
PgBackendStatus *beentry;
const char *activity;
+ char *clipped_activity;
+ text *ret;
if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
activity = "<backend information not available>";
else if (!has_privs_of_role(GetUserId(), beentry->st_userid))
activity = "<insufficient privilege>";
- else if (*(beentry->st_activity) == '\0')
+ else if (*(beentry->st_activity_raw) == '\0')
activity = "<command string not enabled>";
else
- activity = beentry->st_activity;
+ activity = beentry->st_activity_raw;
- PG_RETURN_TEXT_P(cstring_to_text(activity));
+ clipped_activity = pgstat_clip_activity(activity);
+ ret = cstring_to_text(activity);
+ pfree(clipped_activity);
+
+ PG_RETURN_TEXT_P(ret);
}
Datum
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 57ac5d41e46..52af0aa5415 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -1003,8 +1003,14 @@ typedef struct PgBackendStatus
/* application name; MUST be null-terminated */
char *st_appname;
- /* current command string; MUST be null-terminated */
- char *st_activity;
+ /*
+ * Current command string; MUST be null-terminated. Note that this string
+ * possibly is truncated in the middle of a multi-byte character. As
+ * activity strings are stored more frequently than read, that allows to
+ * move the cost of correct truncation to the display side. Use
+ * pgstat_clip_activity() to truncate correctly.
+ */
+ char *st_activity_raw;
/*
* Command progress reporting. Any command which wishes can advertise
@@ -1193,6 +1199,8 @@ extern PgStat_BackendFunctionEntry *find_funcstat_entry(Oid func_id);
extern void pgstat_initstats(Relation rel);
+extern char *pgstat_clip_activity(const char *activity);
+
/* ----------
* pgstat_report_wait_start() -
*
generated by cgit v1.2.3 (git 2.25.1) at 2025-06-01 18:16:01 +0000