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Factor out advisory locking code into advisory_lock()

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Also, some further small fixes of error messages, comments,
marking dubious kludges (e.g. strchr() to determine schema name).
This commit is contained in:
Josh Kupershmidt
2013-06-22 09:35:19 -04:00
parent 673eac7b42
commit bebe6ffb2b
1 changed files with 54 additions and 46 deletions
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98
bin/pg_repack.c
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@ -184,6 +184,7 @@ static bool rebuild_indexes(const repack_table *table);
static char *getstr(PGresult *res, int row, int col);
static Oid getoid(PGresult *res, int row, int col);
static bool advisory_lock(PGconn *conn, const char *relid);
static bool lock_exclusive(PGconn *conn, const char *relid, const char *lock_query, bool start_xact);
static bool kill_ddl(PGconn *conn, Oid relid, bool terminate);
static bool lock_access_share(PGconn *conn, Oid relid, const char *target_name);
@ -1005,26 +1006,12 @@ repack_one_table(const repack_table *table, const char *orderby)
*/
elog(DEBUG2, "---- setup ----");
/* Obtain an advisory lock on the table's OID, to make sure no other
* pg_repack is working on the table. (Not a real concern with only
* full-table repacks, but mainly for index-only repacks.)
*/
params[0] = utoa(table->target_oid, buffer);
res = pgut_execute(connection, "SELECT pg_try_advisory_lock($1::bigint)",
1, params);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
elog(ERROR, "%s", PQerrorMessage(connection));
goto cleanup;
}
else if (strcmp(getstr(res, 0, 0), "t") != 0)
{
elog(WARNING, "Another pg_repack command may be running on the table. Please try again later.");
goto cleanup;
}
CLEARPGRES(res);
if (!(lock_exclusive(connection, utoa(table->target_oid, buffer), table->lock_table, TRUE)))
if (!advisory_lock(connection, buffer))
goto cleanup;
if (!(lock_exclusive(connection, buffer, table->lock_table, TRUE)))
{
elog(WARNING, "lock_exclusive() failed for %s", table->target_name);
goto cleanup;
@ -1465,6 +1452,40 @@ lock_access_share(PGconn *conn, Oid relid, const char *target_name)
}
/* XXX: Make sure that repack_one_table() also obtains an advisory
* lock on the table, so that we can't have a table-wide repack running
* along with an indexes-only repack. Also, since advisory locks are
* 8 bytes wide and OIDs are only 4 bytes, consider using our own prefix
* rather than just the table OID, to avoid inadvertent conflict with
* other applications using advisory locks.
*/
/* Obtain an advisory lock on the table's OID, to make sure no other
* pg_repack is working on the table. This is not so much a concern with
* full-table repacks, but mainly so that index-only repacks don't interfere
* with each other or a full-table repack.
*/
static bool advisory_lock(PGconn *conn, const char *relid)
{
PGresult *res = NULL;
bool ret = false;
res = pgut_execute(conn, "SELECT pg_try_advisory_lock($1::bigint)",
1, &relid);
if (PQresultStatus(res) != PGRES_TUPLES_OK) {
elog(ERROR, "%s", PQerrorMessage(connection));
}
else if (strcmp(getstr(res, 0, 0), "t") != 0) {
elog(WARNING, "Another pg_repack command may be running on the table. Please try again later.");
}
else {
ret = true;
}
CLEARPGRES(res);
return ret;
}
/*
* Try acquire an ACCESS EXCLUSIVE table lock, avoiding deadlocks and long
* waits by killing off other sessions.
@ -1668,12 +1689,14 @@ cleanup:
* Call repack_one_index for each of the indexes
*/
static bool
repack_all_indexes(char *errbuf, size_t errsize){
repack_all_indexes(char *errbuf, size_t errsize)
{
bool ret = false;
PGresult *res = NULL, *res2 = NULL;
PGresult *res = NULL;
int i;
int num;
StringInfoData sql;
char buffer[12];
const char *params[1];
const char *table_name = NULL;
const char *schema_name = NULL;
@ -1715,7 +1738,7 @@ repack_all_indexes(char *errbuf, size_t errsize){
}
}
// seperate schema name and index name
// separate schema name and index name. FIXME: kludge
pos = strchr(params[0], '.');
if (pos)
{
@ -1751,7 +1774,7 @@ repack_all_indexes(char *errbuf, size_t errsize){
}
}
// seperate schema name and table name
// separate schema name and table name. FIXME: kludge
pos = strchr(params[0], '.');
if (pos)
{
@ -1763,30 +1786,14 @@ repack_all_indexes(char *errbuf, size_t errsize){
table_name = params[0];
}
/* XXX: Make sure that repack_one_table() also obtains an advisory
* lock on the table, so that we can't have a table-wide repack running
* along with an indexes-only repack. Also, since advisory locks are
* 8 bytes wide and OIDs are only 4 bytes, consider using our own prefix
* rather than just the table OID, to avoid inadvertent conflict with
* other applications using advisory locks.
/* Check if any concurrent pg_repack command is being run on the same
* table.
*/
/* Check if any concurrent pg_repack command is being run on the same table */
initStringInfo(&sql);
appendStringInfo(&sql, "SELECT pg_try_advisory_lock(%u)", getoid(res, 0, 3));
res2 = execute_elevel(sql.data, 0, NULL, DEBUG2);
if (PQresultStatus(res2) != PGRES_TUPLES_OK)
{
elog(ERROR, "%s", PQerrorMessage(connection));
if (!advisory_lock(connection, utoa(getoid(res, 0, 3), buffer))) {
snprintf(errbuf, errsize, "Unable to obtain advisory lock on %s",
table_name);
goto cleanup;
}
else if (strcmp(getstr(res2, 0, 0), "t") != 0)
{
snprintf(errbuf, errsize, "Another pg_repack command may be running on the table. Please try again later.");
goto cleanup;
}
for (i = 0; i < num; i++)
{
char *isvalid = getstr(res, i, 2);
@ -1797,9 +1804,11 @@ repack_all_indexes(char *errbuf, size_t errsize){
else
elog(INFO, "repacking index \"%s\"", getstr(res, i, 0));
if (!(repack_one_index(getoid(res, i, 3), table_name, getoid(res, i, 1), schema_name)))
if (!(repack_one_index(getoid(res, i, 3), table_name, getoid(res, i, 1), schema_name))) {
/* FIXME: fill in errbuf here */
goto cleanup;
}
}
else
if (schema_name)
elog(WARNING, "skipping invalid index: %s.%s", schema_name, getstr(res, i, 0));
@ -1810,7 +1819,6 @@ repack_all_indexes(char *errbuf, size_t errsize){
cleanup:
CLEARPGRES(res);
CLEARPGRES(res2);
disconnect();
termStringInfo(&sql);
return ret;