Add hooks for hypertable drops

To properly clean up the OSM catalog we need a way to reliably track
hypertable deletion (including internal hypertables for CAGGS).

src/CMakeLists.txt

@@ -31,6 +31,7 @@ set(SOURCES
     init.c
     jsonb_utils.c
     license_guc.c
+    osm_callbacks.c
     partitioning.c
     process_utility.c
     scanner.c

src/chunk.c

@@ -54,6 +54,7 @@
 #include "hypercube.h"
 #include "hypertable.h"
 #include "hypertable_cache.h"
+#include "osm_callbacks.h"
 #include "partitioning.h"
 #include "process_utility.h"
 #include "scan_iterator.h"
@@ -1156,27 +1157,15 @@ ts_chunk_create_only_table(Hypertable *ht, Hypercube *cube, const char *schema_n
 	return chunk;
 }
 
-#if PG14_GE
-#define OSM_CHUNK_INSERT_CHECK_HOOK "osm_chunk_insert_check_hook"
-typedef int (*ts_osm_chunk_insert_hook_type)(Oid ht_oid, int64 range_start, int64 range_end);
-static ts_osm_chunk_insert_hook_type
-get_osm_chunk_insert_hook()
-{
-	ts_osm_chunk_insert_hook_type *func_ptr =
-		(ts_osm_chunk_insert_hook_type *) find_rendezvous_variable(OSM_CHUNK_INSERT_CHECK_HOOK);
-	return *func_ptr;
-}
-#endif
-
 static Chunk *
 chunk_create_from_hypercube_after_lock(const Hypertable *ht, Hypercube *cube,
 									   const char *schema_name, const char *table_name,
 									   const char *prefix)
 {
 #if PG14_GE
-	ts_osm_chunk_insert_hook_type insert_func_ptr = get_osm_chunk_insert_hook();
+	OsmCallbacks *callbacks = ts_get_osm_callbacks();
 
-	if (insert_func_ptr)
+	if (callbacks)
 	{
 		/* OSM only uses first dimension . doesn't work with multinode tables yet*/
 		Dimension *dim = &ht->space->dimensions[0];
@@ -1185,7 +1174,10 @@ chunk_create_from_hypercube_after_lock(const Hypertable *ht, Hypercube *cube,
 			ts_internal_to_time_int64(cube->slices[0]->fd.range_start, dim->fd.column_type);
 		int64 range_end =
 			ts_internal_to_time_int64(cube->slices[0]->fd.range_end, dim->fd.column_type);
-		int chunk_exists = insert_func_ptr(ht->main_table_relid, range_start, range_end);
+
+		int chunk_exists =
+			callbacks->chunk_insert_check_hook(ht->main_table_relid, range_start, range_end);
+
 		if (chunk_exists)
 		{
 			Oid outfuncid = InvalidOid;

src/hypertable.c

@@ -63,6 +63,7 @@
 #include "cross_module_fn.h"
 #include "scan_iterator.h"
 #include "debug_assert.h"
+#include "osm_callbacks.h"
 
 Oid
 ts_rel_get_owner(Oid relid)
@@ -625,6 +626,20 @@ hypertable_tuple_delete(TupleInfo *ti, void *data)
 			ts_hypertable_drop(compressed_hypertable, DROP_RESTRICT);
 	}
 
+#if PG14_GE
+	OsmCallbacks *callbacks = ts_get_osm_callbacks();
+
+	/* Invoke the OSM callback if set */
+	if (callbacks)
+	{
+		Name schema_name =
+			DatumGetName(slot_getattr(ti->slot, Anum_hypertable_schema_name, &isnull));
+		Name table_name = DatumGetName(slot_getattr(ti->slot, Anum_hypertable_table_name, &isnull));
+
+		callbacks->hypertable_drop_hook(NameStr(*schema_name), NameStr(*table_name));
+	}
+#endif
+
 	ts_catalog_database_info_become_owner(ts_catalog_database_info_get(), &sec_ctx);
 	ts_catalog_delete_tid(ti->scanrel, ts_scanner_get_tuple_tid(ti));
 	ts_catalog_restore_user(&sec_ctx);

src/osm_callbacks.c

@@ -0,0 +1,18 @@
+/*
+ * This file and its contents are licensed under the Apache License 2.0.
+ * Please see the included NOTICE for copyright information and
+ * LICENSE-APACHE for a copy of the license.
+ */
+#include "osm_callbacks.h"
+
+#include <fmgr.h>
+
+#define OSM_CALLBACKS_VAR_NAME "osm_callbacks"
+
+OsmCallbacks *
+ts_get_osm_callbacks(void)
+{
+	OsmCallbacks **ptr = (OsmCallbacks **) find_rendezvous_variable(OSM_CALLBACKS_VAR_NAME);
+
+	return *ptr;
+}

src/osm_callbacks.h

@@ -0,0 +1,29 @@
+/*
+ * This file and its contents are licensed under the Apache License 2.0.
+ * Please see the included NOTICE for copyright information and
+ * LICENSE-APACHE for a copy of the license.
+ */
+#ifndef TIMESCALEDB_OSM_CALLBACKS_H
+#define TIMESCALEDB_OSM_CALLBACKS_H
+
+#include <postgres.h>
+#include <catalog/objectaddress.h>
+
+typedef int (*chunk_insert_check_hook_type)(Oid ht_oid, int64 range_start, int64 range_end);
+typedef void (*hypertable_drop_hook_type)(const char *schema_name, const char *table_name);
+
+/*
+ * Object Storage Manager callbacks.
+ *
+ * chunk_insert_check_hook - checks whether the specified range is managed by OSM
+ * hypertable_drop_hook - used for OSM catalog cleanups
+ */
+typedef struct
+{
+	chunk_insert_check_hook_type chunk_insert_check_hook;
+	hypertable_drop_hook_type hypertable_drop_hook;
+} OsmCallbacks;
+
+extern OsmCallbacks *ts_get_osm_callbacks(void);
+
+#endif /* TIMESCALEDB_OSM_CALLBACKS_H */

tsl/test/expected/chunk_utils_internal.out

@@ -439,6 +439,33 @@ SELECT * FROM hyper1_cagg ORDER BY 1;
      30 |     2
 (1 row)
 
+-- check that dropping cagg triggers OSM callback
+SELECT ts_setup_osm_hook();
+ ts_setup_osm_hook 
+-------------------
+
+(1 row)
+
+BEGIN;
+DROP MATERIALIZED VIEW hyper1_cagg CASCADE;
+NOTICE:  drop cascades to table _timescaledb_internal._hyper_4_9_chunk
+NOTICE:  hypertable_drop_hook
+DROP TABLE test1.hyper1;
+NOTICE:  hypertable_drop_hook
+ROLLBACK;
+BEGIN;
+DROP TABLE test1.hyper1 CASCADE;
+NOTICE:  drop cascades to 3 other objects
+NOTICE:  drop cascades to table _timescaledb_internal._hyper_4_9_chunk
+NOTICE:  hypertable_drop_hook
+NOTICE:  hypertable_drop_hook
+ROLLBACK;
+SELECT ts_undo_osm_hook();
+ ts_undo_osm_hook 
+------------------
+
+(1 row)
+
 --TEST error case (un)freeze a non-chunk
 CREATE TABLE nochunk_tab( a timestamp, b integer);
 \set ON_ERROR_STOP 0
@@ -629,6 +656,7 @@ SELECT ts_setup_osm_hook();
 \set ON_ERROR_STOP 0
 --the mock hook returns true always. so cannot create a new chunk on the hypertable
 INSERT INTO ht_try VALUES ('2022-06-05 01:00', 222, 222);
+NOTICE:  chunk_insert_check_hook
 ERROR:  Cannot insert into tiered chunk range of public.ht_try - attempt to create new chunk with range  [Sat Jun 04 17:00:00 2022 PDT Sun Jun 05 17:00:00 2022 PDT] failed
 \set ON_ERROR_STOP 1
 SELECT ts_undo_osm_hook();

tsl/test/sql/chunk_utils_internal.sql

@@ -267,6 +267,17 @@ SELECT  _timescaledb_internal.drop_chunk( :'CHNAME1');
 SELECT * from test1.hyper1 ORDER BY 1;
 SELECT * FROM hyper1_cagg ORDER BY 1;
 
+-- check that dropping cagg triggers OSM callback
+SELECT ts_setup_osm_hook();
+BEGIN;
+DROP MATERIALIZED VIEW hyper1_cagg CASCADE;
+DROP TABLE test1.hyper1;
+ROLLBACK;
+BEGIN;
+DROP TABLE test1.hyper1 CASCADE;
+ROLLBACK;
+SELECT ts_undo_osm_hook();
+
 --TEST error case (un)freeze a non-chunk
 CREATE TABLE nochunk_tab( a timestamp, b integer);
 \set ON_ERROR_STOP 0

tsl/test/src/test_chunk_stats.c

@@ -12,6 +12,7 @@
 #include "bgw/job.h"
 #include "export.h"
 #include "bgw_policy/chunk_stats.h"
+#include "osm_callbacks.h"
 
 TS_FUNCTION_INFO_V1(ts_test_chunk_stats_insert);
 
@@ -35,34 +36,45 @@ ts_test_chunk_stats_insert(PG_FUNCTION_ARGS)
 	PG_RETURN_NULL();
 }
 
+typedef int (*chunk_insert_check_hook_type)(Oid, int64, int64);
+typedef void (*hypertable_drop_hook_type)(const char *, const char *);
+
 static int
 osm_insert_hook_mock(Oid ht_oid, int64 range_start, int64 range_end)
 {
 	/* always return true */
+	elog(NOTICE, "chunk_insert_check_hook");
 	return 1;
 }
 
+static void
+osm_ht_drop_hook_mock(const char *schema_name, const char *table_name)
+{
+	elog(NOTICE, "hypertable_drop_hook");
+}
+
+OsmCallbacks fake_osm_callbacks = { .chunk_insert_check_hook = osm_insert_hook_mock,
+									.hypertable_drop_hook = osm_ht_drop_hook_mock };
+
 /*
  * Dummy function to mock OSM_INSERT hook called at chunk creation for tiered data
  */
 TS_FUNCTION_INFO_V1(ts_setup_osm_hook);
 Datum
 ts_setup_osm_hook(PG_FUNCTION_ARGS)
 {
-	typedef int (*MOCK_OSM_INSERT_HOOK)(Oid, int64, int64);
-	MOCK_OSM_INSERT_HOOK *var =
-		(MOCK_OSM_INSERT_HOOK *) find_rendezvous_variable("osm_chunk_insert_check_hook");
-	*var = osm_insert_hook_mock;
+	OsmCallbacks **ptr = (OsmCallbacks **) find_rendezvous_variable("osm_callbacks");
+	*ptr = &fake_osm_callbacks;
+
 	PG_RETURN_NULL();
 }
 
 TS_FUNCTION_INFO_V1(ts_undo_osm_hook);
 Datum
 ts_undo_osm_hook(PG_FUNCTION_ARGS)
 {
-	typedef int (*MOCK_OSM_INSERT_HOOK)(Oid, int64, int64);
-	MOCK_OSM_INSERT_HOOK *var =
-		(MOCK_OSM_INSERT_HOOK *) find_rendezvous_variable("osm_chunk_insert_check_hook");
-	*var = NULL;
+	OsmCallbacks **ptr = (OsmCallbacks **) find_rendezvous_variable("osm_callbacks");
+	*ptr = NULL;
+
 	PG_RETURN_NULL();
 }