pg_upgrade: Parallelize retrieving loadable libraries.

This commit makes use of the new task framework in pg_upgrade to
parallelize retrieving the names of all libraries referenced by
non-built-in C functions.  This step will now process multiple
databases concurrently when pg_upgrade's --jobs option is provided
a value greater than 1.

Reviewed-by: Daniel Gustafsson, Ilya Gladyshev
Discussion: https://postgr.es/m/20240516211638.GA1688936%40nathanxps13

diff --git a/src/bin/pg_upgrade/function.c b/src/bin/pg_upgrade/function.c
index 7e3abed0985d5b11950de9a154c68c4f085a42eb..bd2b8b6bd6698b58ae048f064cf12bad8ceaffdf 100644 (file)
--- a/src/bin/pg_upgrade/function.c
+++ b/src/bin/pg_upgrade/function.c
@@ -42,6 +42,30 @@ library_name_compare(const void *p1, const void *p2)
                      ((const LibraryInfo *) p2)->dbnum);
 }
 
+/*
+ * Private state for get_loadable_libraries()'s UpgradeTask.
+ */
+struct loadable_libraries_state
+{
+   PGresult  **ress;           /* results for each database */
+   int         totaltups;      /* number of tuples in all results */
+};
+
+/*
+ * Callback function for processing results of query for
+ * get_loadable_libraries()'s UpgradeTask.  This function stores the results
+ * for later use within get_loadable_libraries().
+ */
+static void
+process_loadable_libraries(DbInfo *dbinfo, PGresult *res, void *arg)
+{
+   struct loadable_libraries_state *state = (struct loadable_libraries_state *) arg;
+
+   AssertVariableIsOfType(&process_loadable_libraries, UpgradeTaskProcessCB);
+
+   state->ress[dbinfo - old_cluster.dbarr.dbs] = res;
+   state->totaltups += PQntuples(res);
+}
 
 /*
  * get_loadable_libraries()
@@ -54,47 +78,41 @@ library_name_compare(const void *p1, const void *p2)
 void
 get_loadable_libraries(void)
 {
-   PGresult  **ress;
    int         totaltups;
    int         dbnum;
    int         n_libinfos;
+   UpgradeTask *task = upgrade_task_create();
+   struct loadable_libraries_state state;
+   char       *query;
 
-   ress = (PGresult **) pg_malloc(old_cluster.dbarr.ndbs * sizeof(PGresult *));
-   totaltups = 0;
+   state.ress = (PGresult **) pg_malloc(old_cluster.dbarr.ndbs * sizeof(PGresult *));
+   state.totaltups = 0;
 
-   /* Fetch all library names, removing duplicates within each DB */
-   for (dbnum = 0; dbnum < old_cluster.dbarr.ndbs; dbnum++)
-   {
-       DbInfo     *active_db = &old_cluster.dbarr.dbs[dbnum];
-       PGconn     *conn = connectToServer(&old_cluster, active_db->db_name);
+   query = psprintf("SELECT DISTINCT probin "
+                    "FROM pg_catalog.pg_proc "
+                    "WHERE prolang = %u AND "
+                    "probin IS NOT NULL AND "
+                    "oid >= %u",
+                    ClanguageId,
+                    FirstNormalObjectId);
 
-       /*
-        * Fetch all libraries containing non-built-in C functions in this DB.
-        */
-       ress[dbnum] = executeQueryOrDie(conn,
-                                       "SELECT DISTINCT probin "
-                                       "FROM pg_catalog.pg_proc "
-                                       "WHERE prolang = %u AND "
-                                       "probin IS NOT NULL AND "
-                                       "oid >= %u;",
-                                       ClanguageId,
-                                       FirstNormalObjectId);
-       totaltups += PQntuples(ress[dbnum]);
-
-       PQfinish(conn);
-   }
+   upgrade_task_add_step(task, query, process_loadable_libraries,
+                         false, &state);
+
+   upgrade_task_run(task, &old_cluster);
+   upgrade_task_free(task);
 
    /*
     * Allocate memory for required libraries and logical replication output
     * plugins.
     */
-   n_libinfos = totaltups + count_old_cluster_logical_slots();
+   n_libinfos = state.totaltups + count_old_cluster_logical_slots();
    os_info.libraries = (LibraryInfo *) pg_malloc(sizeof(LibraryInfo) * n_libinfos);
    totaltups = 0;
 
    for (dbnum = 0; dbnum < old_cluster.dbarr.ndbs; dbnum++)
    {
-       PGresult   *res = ress[dbnum];
+       PGresult   *res = state.ress[dbnum];
        int         ntups;
        int         rowno;
        LogicalSlotInfoArr *slot_arr = &old_cluster.dbarr.dbs[dbnum].slot_arr;
@@ -129,7 +147,8 @@ get_loadable_libraries(void)
        }
    }
 
-   pg_free(ress);
+   pg_free(state.ress);
+   pg_free(query);
 
    os_info.num_libraries = totaltups;
 }