Avoid crashing when a table is deleted while we're on the process of checking

it.

Per report from Tom Lane based on buildfarm evidence.
This commit is contained in:
Alvaro Herrera 2008-07-17 21:02:31 +00:00
parent a41f73a092
commit 46c5a212ec
1 changed files with 45 additions and 49 deletions

View File

@ -55,7 +55,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.80 2008/07/01 02:09:34 tgl Exp $
* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.81 2008/07/17 21:02:31 alvherre Exp $
*
*-------------------------------------------------------------------------
*/
@ -176,6 +176,9 @@ typedef struct autovac_table
int at_vacuum_cost_delay;
int at_vacuum_cost_limit;
bool at_wraparound;
char *at_relname;
char *at_nspname;
char *at_datname;
} autovac_table;
/*-------------
@ -282,15 +285,13 @@ static void relation_needs_vacanalyze(Oid relid, Form_pg_autovacuum avForm,
PgStat_StatTabEntry *tabentry, bool *dovacuum,
bool *doanalyze, bool *wraparound);
static void autovacuum_do_vac_analyze(Oid relid, bool dovacuum,
bool doanalyze, int freeze_min_age,
bool for_wraparound,
static void autovacuum_do_vac_analyze(autovac_table *tab,
BufferAccessStrategy bstrategy);
static HeapTuple get_pg_autovacuum_tuple_relid(Relation avRel, Oid relid);
static PgStat_StatTabEntry *get_pgstat_tabentry_relid(Oid relid, bool isshared,
PgStat_StatDBEntry *shared,
PgStat_StatDBEntry *dbentry);
static void autovac_report_activity(VacuumStmt *vacstmt, Oid relid);
static void autovac_report_activity(autovac_table *tab);
static void avl_sighup_handler(SIGNAL_ARGS);
static void avl_sigusr1_handler(SIGNAL_ARGS);
static void avl_sigterm_handler(SIGNAL_ARGS);
@ -2061,9 +2062,6 @@ do_autovacuum(void)
autovac_table *tab;
WorkerInfo worker;
bool skipit;
char *datname,
*nspname,
*relname;
CHECK_FOR_INTERRUPTS();
@ -2158,13 +2156,17 @@ do_autovacuum(void)
/*
* Save the relation name for a possible error message, to avoid a
* catalog lookup in case of an error. Note: they must live in a
* long-lived memory context because we call vacuum and analyze in
* different transactions.
* catalog lookup in case of an error. If any of these return NULL,
* then the relation has been dropped since last we checked; skip it.
* Note: they must live in a long-lived memory context because we call
* vacuum and analyze in different transactions.
*/
datname = get_database_name(MyDatabaseId);
nspname = get_namespace_name(get_rel_namespace(tab->at_relid));
relname = get_rel_name(tab->at_relid);
tab->at_relname = get_rel_name(tab->at_relid);
tab->at_nspname = get_namespace_name(get_rel_namespace(tab->at_relid));
tab->at_datname = get_database_name(MyDatabaseId);
if (!tab->at_relname || !tab->at_nspname || !tab->at_datname)
goto deleted;
/*
* We will abort vacuuming the current table if something errors out,
@ -2175,12 +2177,7 @@ do_autovacuum(void)
{
/* have at it */
MemoryContextSwitchTo(TopTransactionContext);
autovacuum_do_vac_analyze(tab->at_relid,
tab->at_dovacuum,
tab->at_doanalyze,
tab->at_freeze_min_age,
tab->at_wraparound,
bstrategy);
autovacuum_do_vac_analyze(tab, bstrategy);
/*
* Clear a possible query-cancel signal, to avoid a late reaction
@ -2199,10 +2196,10 @@ do_autovacuum(void)
HOLD_INTERRUPTS();
if (tab->at_dovacuum)
errcontext("automatic vacuum of table \"%s.%s.%s\"",
datname, nspname, relname);
tab->at_datname, tab->at_nspname, tab->at_relname);
else
errcontext("automatic analyze of table \"%s.%s.%s\"",
datname, nspname, relname);
tab->at_datname, tab->at_nspname, tab->at_relname);
EmitErrorReport();
/* this resets the PGPROC flags too */
@ -2219,10 +2216,14 @@ do_autovacuum(void)
/* the PGPROC flags are reset at the next end of transaction */
/* be tidy */
deleted:
if (tab->at_datname != NULL)
pfree(tab->at_datname);
if (tab->at_nspname != NULL)
pfree(tab->at_nspname);
if (tab->at_relname != NULL)
pfree(tab->at_relname);
pfree(tab);
pfree(datname);
pfree(nspname);
pfree(relname);
/* remove my info from shared memory */
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
@ -2299,6 +2300,8 @@ get_pgstat_tabentry_relid(Oid relid, bool isshared, PgStat_StatDBEntry *shared,
* Recheck whether a plain table still needs vacuum or analyze; be it because
* it does directly, or because its TOAST table does. Return value is a valid
* autovac_table pointer if it does, NULL otherwise.
*
* Note that the returned autovac_table does not have the name fields set.
*/
static autovac_table *
table_recheck_autovac(Oid relid)
@ -2437,6 +2440,9 @@ table_recheck_autovac(Oid relid)
tab->at_vacuum_cost_limit = vac_cost_limit;
tab->at_vacuum_cost_delay = vac_cost_delay;
tab->at_wraparound = wraparound || toast_wraparound;
tab->at_relname = NULL;
tab->at_nspname = NULL;
tab->at_datname = NULL;
}
heap_close(avRel, AccessShareLock);
@ -2607,8 +2613,7 @@ relation_needs_vacanalyze(Oid relid,
* Vacuum and/or analyze the specified table
*/
static void
autovacuum_do_vac_analyze(Oid relid, bool dovacuum, bool doanalyze,
int freeze_min_age, bool for_wraparound,
autovacuum_do_vac_analyze(autovac_table *tab,
BufferAccessStrategy bstrategy)
{
VacuumStmt vacstmt;
@ -2617,18 +2622,18 @@ autovacuum_do_vac_analyze(Oid relid, bool dovacuum, bool doanalyze,
MemSet(&vacstmt, 0, sizeof(vacstmt));
vacstmt.type = T_VacuumStmt;
vacstmt.vacuum = dovacuum;
vacstmt.vacuum = tab->at_dovacuum;
vacstmt.full = false;
vacstmt.analyze = doanalyze;
vacstmt.freeze_min_age = freeze_min_age;
vacstmt.analyze = tab->at_doanalyze;
vacstmt.freeze_min_age = tab->at_freeze_min_age;
vacstmt.verbose = false;
vacstmt.relation = NULL; /* not used since we pass a relid */
vacstmt.va_cols = NIL;
/* Let pgstat know what we're doing */
autovac_report_activity(&vacstmt, relid);
autovac_report_activity(tab);
vacuum(&vacstmt, relid, bstrategy, for_wraparound, true);
vacuum(&vacstmt, tab->at_relid, bstrategy, tab->at_wraparound, true);
}
/*
@ -2643,37 +2648,28 @@ autovacuum_do_vac_analyze(Oid relid, bool dovacuum, bool doanalyze,
* bother to report "<IDLE>" or some such.
*/
static void
autovac_report_activity(VacuumStmt *vacstmt, Oid relid)
autovac_report_activity(autovac_table *tab)
{
char *relname = get_rel_name(relid);
char *nspname = get_namespace_name(get_rel_namespace(relid));
#define MAX_AUTOVAC_ACTIV_LEN (NAMEDATALEN * 2 + 32)
char activity[MAX_AUTOVAC_ACTIV_LEN];
char activity[MAX_AUTOVAC_ACTIV_LEN];
int len;
/* Report the command and possible options */
if (vacstmt->vacuum)
if (tab->at_dovacuum)
snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
"autovacuum: VACUUM%s",
vacstmt->analyze ? " ANALYZE" : "");
tab->at_doanalyze ? " ANALYZE" : "");
else
snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
"autovacuum: ANALYZE");
/*
* Report the qualified name of the relation.
*
* Paranoia is appropriate here in case relation was recently dropped ---
* the lsyscache routines we just invoked will return NULL rather than
* failing.
*/
if (relname && nspname)
{
int len = strlen(activity);
len = strlen(activity);
snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len,
" %s.%s", nspname, relname);
}
snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len,
" %s.%s", tab->at_nspname, tab->at_relname);
/* Set statement_timestamp() to current time for pg_stat_activity */
SetCurrentStatementStartTimestamp();