diff options
| -rw-r--r-- | src/backend/tcop/postgres.c | 3 | ||||
| -rw-r--r-- | src/backend/utils/misc/guc.c | 78 | ||||
| -rw-r--r-- | src/include/utils/guc.h | 1 | ||||
| -rw-r--r-- | src/include/utils/guc_tables.h | 5 |
4 files changed, 80 insertions, 7 deletions
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index 7c5f7c775b9..34ed0e7558c 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -4229,6 +4229,9 @@ PostgresMain(int argc, char *argv[], pgstat_report_activity(STATE_IDLE, NULL); } + /* Report any recently-changed GUC options */ + ReportChangedGUCOptions(); + ReadyForQuery(whereToSendOutput); send_ready_for_query = false; } diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index bb34630e8e4..245a3472bc8 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -4822,6 +4822,8 @@ static bool guc_dirty; /* true if need to do commit/abort work */ static bool reporting_enabled; /* true to enable GUC_REPORT */ +static bool report_needed; /* true if any GUC_REPORT reports are needed */ + static int GUCNestLevel = 0; /* 1 when in main transaction */ @@ -5452,6 +5454,7 @@ InitializeOneGUCOption(struct config_generic *gconf) gconf->reset_scontext = PGC_INTERNAL; gconf->stack = NULL; gconf->extra = NULL; + gconf->last_reported = NULL; gconf->sourcefile = NULL; gconf->sourceline = 0; @@ -5828,7 +5831,10 @@ ResetAllOptions(void) gconf->scontext = gconf->reset_scontext; if (gconf->flags & GUC_REPORT) - ReportGUCOption(gconf); + { + gconf->status |= GUC_NEEDS_REPORT; + report_needed = true; + } } } @@ -6215,7 +6221,10 @@ AtEOXact_GUC(bool isCommit, int nestLevel) /* Report new value if we changed it */ if (changed && (gconf->flags & GUC_REPORT)) - ReportGUCOption(gconf); + { + gconf->status |= GUC_NEEDS_REPORT; + report_needed = true; + } } /* end of stack-popping loop */ if (stack != NULL) @@ -6257,17 +6266,60 @@ BeginReportingGUCOptions(void) if (conf->flags & GUC_REPORT) ReportGUCOption(conf); } + + report_needed = false; +} + +/* + * ReportChangedGUCOptions: report recently-changed GUC_REPORT variables + * + * This is called just before we wait for a new client query. + * + * By handling things this way, we ensure that a ParameterStatus message + * is sent at most once per variable per query, even if the variable + * changed multiple times within the query. That's quite possible when + * using features such as function SET clauses. Function SET clauses + * also tend to cause values to change intraquery but eventually revert + * to their prevailing values; ReportGUCOption is responsible for avoiding + * redundant reports in such cases. + */ +void +ReportChangedGUCOptions(void) +{ + /* Quick exit if not (yet) enabled */ + if (!reporting_enabled) + return; + + /* Quick exit if no values have been changed */ + if (!report_needed) + return; + + /* Transmit new values of interesting variables */ + for (int i = 0; i < num_guc_variables; i++) + { + struct config_generic *conf = guc_variables[i]; + + if ((conf->flags & GUC_REPORT) && (conf->status & GUC_NEEDS_REPORT)) + ReportGUCOption(conf); + } + + report_needed = false; } /* * ReportGUCOption: if appropriate, transmit option value to frontend + * + * We need not transmit the value if it's the same as what we last + * transmitted. However, clear the NEEDS_REPORT flag in any case. */ static void ReportGUCOption(struct config_generic *record) { - if (reporting_enabled && (record->flags & GUC_REPORT)) + char *val = _ShowOption(record, false); + + if (record->last_reported == NULL || + strcmp(val, record->last_reported) != 0) { - char *val = _ShowOption(record, false); StringInfoData msgbuf; pq_beginmessage(&msgbuf, 'S'); @@ -6275,8 +6327,19 @@ ReportGUCOption(struct config_generic *record) pq_sendstring(&msgbuf, val); pq_endmessage(&msgbuf); - pfree(val); + /* + * We need a long-lifespan copy. If strdup() fails due to OOM, we'll + * set last_reported to NULL and thereby possibly make a duplicate + * report later. + */ + if (record->last_reported) + free(record->last_reported); + record->last_reported = strdup(val); } + + pfree(val); + + record->status &= ~GUC_NEEDS_REPORT; } /* @@ -7695,7 +7758,10 @@ set_config_option(const char *name, const char *value, } if (changeVal && (record->flags & GUC_REPORT)) - ReportGUCOption(record); + { + record->status |= GUC_NEEDS_REPORT; + report_needed = true; + } return changeVal ? 1 : -1; } diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h index 073c8f3e062..6a20a3bcece 100644 --- a/src/include/utils/guc.h +++ b/src/include/utils/guc.h @@ -363,6 +363,7 @@ extern void AtStart_GUC(void); extern int NewGUCNestLevel(void); extern void AtEOXact_GUC(bool isCommit, int nestLevel); extern void BeginReportingGUCOptions(void); +extern void ReportChangedGUCOptions(void); extern void ParseLongOption(const char *string, char **name, char **value); extern bool parse_int(const char *value, int *result, int flags, const char **hintmsg); diff --git a/src/include/utils/guc_tables.h b/src/include/utils/guc_tables.h index 04431d0eb25..7f36e1146f2 100644 --- a/src/include/utils/guc_tables.h +++ b/src/include/utils/guc_tables.h @@ -161,6 +161,8 @@ struct config_generic GucContext reset_scontext; /* context that set the reset value */ GucStack *stack; /* stacked prior values */ void *extra; /* "extra" pointer for current actual value */ + char *last_reported; /* if variable is GUC_REPORT, value last sent + * to client (NULL if not yet sent) */ char *sourcefile; /* file current setting is from (NULL if not * set in config file) */ int sourceline; /* line in source file */ @@ -172,7 +174,8 @@ struct config_generic * Caution: the GUC_IS_IN_FILE bit is transient state for ProcessConfigFile. * Do not assume that its value represents useful information elsewhere. */ -#define GUC_PENDING_RESTART 0x0002 +#define GUC_PENDING_RESTART 0x0002 /* changed value cannot be applied yet */ +#define GUC_NEEDS_REPORT 0x0004 /* new value must be reported to client */ /* GUC records for specific variable types */ |