Fix execution of refresh_caggs from user actions

Segmentation fault was ocurring when calling the procedure
`refresh_continous_aggregate` from an user defined action (job).

Fixed it by adding the `SPI_connect_ext/SPI_finish` during the
execution because there are underlying SPI calls that was leading
us to an invalid SPI state (nonexistent `_SPI_current` global).

Fixes #3145

tsl/src/continuous_aggs/refresh.c

@@ -14,6 +14,7 @@
 #include <storage/lmgr.h>
 #include <miscadmin.h>
 #include <fmgr.h>
+#include <executor/spi.h>
 
 #include <catalog.h>
 #include <continuous_agg.h>
@@ -505,6 +506,7 @@ continuous_agg_refresh(PG_FUNCTION_ARGS)
 		refresh_window.end = ts_time_get_noend_or_max(refresh_window.type);
 
 	continuous_agg_refresh_internal(cagg, &refresh_window, CAGG_REFRESH_WINDOW);
+
 	PG_RETURN_VOID();
 }
 
@@ -573,6 +575,11 @@ continuous_agg_refresh_internal(const ContinuousAgg *cagg,
 	int64 computed_invalidation_threshold;
 	int64 invalidation_threshold;
 	int64 max_bucket_width;
+	int rc;
+
+	/* Connect to SPI manager due to the underlying SPI calls */
+	if ((rc = SPI_connect_ext(SPI_OPT_NONATOMIC) != SPI_OK_CONNECT))
+		elog(ERROR, "SPI_connect failed: %s", SPI_result_code_string(rc));
 
 	/* Like regular materialized views, require owner to refresh. */
 	if (!pg_class_ownercheck(cagg->relid, GetUserId()))
@@ -651,29 +658,26 @@ continuous_agg_refresh_internal(const ContinuousAgg *cagg,
 	if (refresh_window.start >= refresh_window.end)
 	{
 		emit_up_to_date_notice(cagg, callctx);
+
+		if ((rc = SPI_finish()) != SPI_OK_FINISH)
+			elog(ERROR, "SPI_finish failed: %s", SPI_result_code_string(rc));
+
 		return;
 	}
 
 	/* Process invalidations in the hypertable invalidation log */
 	invalidation_process_hypertable_log(cagg, refresh_window.type);
 
-	/* Start a new transaction. Note that this invalidates previous memory
+	/* Commit and Start a new transaction */
-	 * allocations (and locks). */
+	SPI_commit_and_chain();
-	PopActiveSnapshot();
-	CommitTransactionCommand();
-	/* See PG commit:84f5c2908dad81e8622b0406beea580e40bb03ac
-	 * When we manage multiple transactions in a procedure, ensure that
-	 * an active outer snapshot exists prior to executing SPI
-	 * (see EnsurePortalSnapshotExists)
-	 */
-	StartTransactionCommand();
-	PushActiveSnapshot(GetTransactionSnapshot());
 
 	cagg = ts_continuous_agg_find_by_mat_hypertable_id(mat_id);
 
 	if (!process_cagg_invalidations_and_refresh(cagg, &refresh_window, callctx, INVALID_CHUNK_ID))
 		emit_up_to_date_notice(cagg, callctx);
-	PopActiveSnapshot();
+
+	if ((rc = SPI_finish()) != SPI_OK_FINISH)
+		elog(ERROR, "SPI_finish failed: %s", SPI_result_code_string(rc));
 }
 
 /*

tsl/test/expected/bgw_custom.out

@@ -279,7 +279,8 @@ BEGIN
     LOOP
     SELECT total_successes, total_failures FROM _timescaledb_internal.bgw_job_stat WHERE job_id=job_param_id INTO r;
     IF (r.total_failures > 0) THEN
-        EXIT;
+        RAISE INFO 'wait_for_job_to_run: job execution failed';
+        RETURN false;
     ELSEIF (r.total_successes = expected_runs) THEN
         RETURN true;
     ELSEIF (r.total_successes > expected_runs) THEN
@@ -288,6 +289,7 @@ BEGIN
         PERFORM pg_sleep(0.1);
     END IF;
     END LOOP;
+    RAISE INFO 'wait_for_job_to_run: timeout after % tries', spins;
     RETURN false;
 END
 $BODY$;
@@ -322,6 +324,12 @@ BEGIN
     COMMIT;
 END
 $$;
+CREATE OR REPLACE PROCEDURE custom_proc5(job_id int, args jsonb) LANGUAGE PLPGSQL AS
+$$
+BEGIN
+    CALL refresh_continuous_aggregate('conditions_summary_daily', '2021-08-01 00:00', '2021-08-31 00:00');
+END
+$$;
 -- Remove any default jobs, e.g., telemetry
 \c :TEST_DBNAME :ROLE_SUPERUSER
 TRUNCATE _timescaledb_config.bgw_job RESTART IDENTITY CASCADE;
@@ -378,6 +386,7 @@ TRUNCATE custom_log;
 -- Forced Exception
 SELECT add_job('custom_proc4', '1h', config := '{"type":"procedure"}'::jsonb, initial_start := now()) AS job_id_3 \gset
 SELECT wait_for_job_to_run(:job_id_3, 1);
+INFO:  wait_for_job_to_run: job execution failed
  wait_for_job_to_run 
 ---------------------
  f
@@ -398,12 +407,12 @@ SELECT delete_job(:job_id_3);
 (1 row)
 
 CREATE TABLE conditions (
-  time TIMESTAMPTZ NOT NULL,
+  time TIMESTAMP NOT NULL,
   location TEXT NOT NULL,
   location2 char(10) NOT NULL,
   temperature DOUBLE PRECISION NULL,
   humidity DOUBLE PRECISION NULL
-);
+) WITH (autovacuum_enabled = FALSE);
 SELECT create_hypertable('conditions', 'time', chunk_time_interval := '15 days'::interval);
     create_hypertable    
 -------------------------
@@ -444,6 +453,34 @@ SELECT * FROM _timescaledb_internal.compressed_chunk_stats ORDER BY chunk_name;
  public            | conditions      | _timescaledb_internal | _hyper_1_3_chunk | Compressed         |                   8192 |                   16384 |                    8192 |                   32768 |                 8192 |                 16384 |                  8192 |                 32768
 (3 rows)
 
+-- Decompress chunks before create the cagg
+SELECT decompress_chunk(c) FROM show_chunks('conditions') c;
+            decompress_chunk            
+----------------------------------------
+ _timescaledb_internal._hyper_1_1_chunk
+ _timescaledb_internal._hyper_1_2_chunk
+ _timescaledb_internal._hyper_1_3_chunk
+(3 rows)
+
+-- Continuous Aggregate
+CREATE MATERIALIZED VIEW conditions_summary_daily
+WITH (timescaledb.continuous) AS
+SELECT location,
+   time_bucket(INTERVAL '1 day', time) AS bucket,
+   AVG(temperature),
+   MAX(temperature),
+   MIN(temperature)
+FROM conditions
+GROUP BY location, bucket
+WITH NO DATA;
+-- Refresh Continous Aggregate by Job
+SELECT add_job('custom_proc5', '1h', config := '{"type":"procedure"}'::jsonb, initial_start := now()) AS job_id_5 \gset
+SELECT wait_for_job_to_run(:job_id_5, 1);
+ wait_for_job_to_run 
+---------------------
+ t
+(1 row)
+
 -- Stop Background Workers
 SELECT _timescaledb_internal.stop_background_workers();
  stop_background_workers 

tsl/test/sql/bgw_custom.sql

@@ -70,7 +70,6 @@ CALL run_job(1004);
 
 SELECT * FROM custom_log ORDER BY job_id, extra;
 
-
 \set ON_ERROR_STOP 0
 -- test bad input
 SELECT delete_job(NULL);
@@ -131,7 +130,8 @@ BEGIN
     LOOP
     SELECT total_successes, total_failures FROM _timescaledb_internal.bgw_job_stat WHERE job_id=job_param_id INTO r;
     IF (r.total_failures > 0) THEN
-        EXIT;
+        RAISE INFO 'wait_for_job_to_run: job execution failed';
+        RETURN false;
     ELSEIF (r.total_successes = expected_runs) THEN
         RETURN true;
     ELSEIF (r.total_successes > expected_runs) THEN
@@ -140,6 +140,7 @@ BEGIN
         PERFORM pg_sleep(0.1);
     END IF;
     END LOOP;
+    RAISE INFO 'wait_for_job_to_run: timeout after % tries', spins;
     RETURN false;
 END
 $BODY$;
@@ -179,6 +180,13 @@ BEGIN
 END
 $$;
 
+CREATE OR REPLACE PROCEDURE custom_proc5(job_id int, args jsonb) LANGUAGE PLPGSQL AS
+$$
+BEGIN
+    CALL refresh_continuous_aggregate('conditions_summary_daily', '2021-08-01 00:00', '2021-08-31 00:00');
+END
+$$;
+
 -- Remove any default jobs, e.g., telemetry
 \c :TEST_DBNAME :ROLE_SUPERUSER
 TRUNCATE _timescaledb_config.bgw_job RESTART IDENTITY CASCADE;
@@ -215,13 +223,15 @@ SELECT * FROM custom_log ORDER BY job_id, extra;
 SELECT delete_job(:job_id_3);
 
 CREATE TABLE conditions (
-  time TIMESTAMPTZ NOT NULL,
+  time TIMESTAMP NOT NULL,
   location TEXT NOT NULL,
   location2 char(10) NOT NULL,
   temperature DOUBLE PRECISION NULL,
   humidity DOUBLE PRECISION NULL
-);
+) WITH (autovacuum_enabled = FALSE);
+
 SELECT create_hypertable('conditions', 'time', chunk_time_interval := '15 days'::interval);
+
 ALTER TABLE conditions
   SET (
     timescaledb.compress,
@@ -241,5 +251,24 @@ SELECT wait_for_job_to_run(:job_id_4, 1);
 -- Chunk compress stats
 SELECT * FROM _timescaledb_internal.compressed_chunk_stats ORDER BY chunk_name;
 
+-- Decompress chunks before create the cagg
+SELECT decompress_chunk(c) FROM show_chunks('conditions') c;
+
+-- Continuous Aggregate
+CREATE MATERIALIZED VIEW conditions_summary_daily
+WITH (timescaledb.continuous) AS
+SELECT location,
+   time_bucket(INTERVAL '1 day', time) AS bucket,
+   AVG(temperature),
+   MAX(temperature),
+   MIN(temperature)
+FROM conditions
+GROUP BY location, bucket
+WITH NO DATA;
+
+-- Refresh Continous Aggregate by Job
+SELECT add_job('custom_proc5', '1h', config := '{"type":"procedure"}'::jsonb, initial_start := now()) AS job_id_5 \gset
+SELECT wait_for_job_to_run(:job_id_5, 1);
+
 -- Stop Background Workers
 SELECT _timescaledb_internal.stop_background_workers();