Add a function to lock OSM chunk's dimension slice

Author: gayyappan

.unreleased/pr_9964

@@ -0,0 +1 @@
+Implements: #9964 Add a function to lock OSM chunk's dimension slice

sql/osm_api.sql

@@ -12,3 +12,12 @@ CREATE OR REPLACE FUNCTION _timescaledb_functions.hypertable_osm_range_update(
     empty BOOL = false
 ) RETURNS BOOL AS '@MODULE_PATHNAME@',
 'ts_hypertable_osm_range_update' LANGUAGE C VOLATILE;
+
+-- Acquires a FOR UPDATE row lock on the dimension slice tuple belonging to the
+-- OSM chunk of the given hypertable. There is exactly one OSM chunk per
+-- hypertable, so this locks its single dimension_slice entry. The lock is held
+-- until the end of the current transaction; nothing is returned.
+CREATE OR REPLACE FUNCTION _timescaledb_functions.lock_osm_chunk_dimension_slice(
+    htoid REGCLASS
+) RETURNS VOID AS '@MODULE_PATHNAME@',
+'ts_lock_osm_chunk_dimension_slice' LANGUAGE C VOLATILE;

sql/updates/reverse-dev.sql

@@ -20,6 +20,8 @@ $$;
 DROP VIEW IF EXISTS _timescaledb_catalog.chunk_constraint;
 DROP FUNCTION IF EXISTS _timescaledb_functions.chunk_constraint_add_table_constraint( integer, name, name);
 
+DROP FUNCTION IF EXISTS _timescaledb_functions.lock_osm_chunk_dimension_slice(regclass);
+
 ALTER TABLE _timescaledb_catalog.hypertable RESET (user_catalog_table);
 ALTER TABLE _timescaledb_catalog.chunk RESET (user_catalog_table);
 

src/hypertable.c

@@ -2690,6 +2690,71 @@ ts_hypertable_osm_range_update(PG_FUNCTION_ARGS)
 	PG_RETURN_BOOL(overlap);
 }
 
+/*
+ * lock_osm_chunk_dimension_slice
+ * 0 hypertable REGCLASS
+ *
+ * Acquires a FOR UPDATE row lock on the dimension slice tuple belonging to the
+ * OSM chunk of the given hypertable. There is exactly one OSM chunk per
+ * hypertable, so this locks its single dimension slice entry. The lock is held
+ * until the end of the current transaction. Returns void.
+ *
+ * Like hypertable_osm_range_update this is meant to be used by OSM to
+ * coordinate access to the OSM chunk's dimension slice; it is not meant to run
+ * on a read-only secondary.
+ */
+TS_FUNCTION_INFO_V1(ts_lock_osm_chunk_dimension_slice);
+Datum
+ts_lock_osm_chunk_dimension_slice(PG_FUNCTION_ARGS)
+{
+	Oid relid = PG_ARGISNULL(0) ? InvalidOid : PG_GETARG_OID(0);
+	Hypertable *ht;
+	const Dimension *time_dim;
+	Cache *hcache;
+
+	Assert(!RecoveryInProgress());
+
+	hcache = ts_hypertable_cache_pin();
+	ht = ts_resolve_hypertable_from_table_or_cagg(hcache, relid, true);
+	Assert(ht != NULL);
+	time_dim = hyperspace_get_open_dimension(ht->space, 0);
+
+	Ensure(time_dim != NULL,
+		   "could not find time dimension for hypertable %s.%s",
+		   quote_identifier(NameStr(ht->fd.schema_name)),
+		   quote_identifier(NameStr(ht->fd.table_name)));
+
+	int32 osm_chunk_id = ts_chunk_get_osm_chunk_id(ht->fd.id);
+	if (osm_chunk_id == INVALID_CHUNK_ID)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				errmsg("no OSM chunk found for hypertable %s.%s",
+					   quote_identifier(NameStr(ht->fd.schema_name)),
+					   quote_identifier(NameStr(ht->fd.table_name))));
+	}
+
+	/*
+	 * Lock the OSM chunk's dimension slice tuple FOR UPDATE. The row lock is
+	 * held until the end of the current transaction.
+	 */
+	DimensionSlice *slice = ts_chunk_get_osm_slice_and_lock(osm_chunk_id,
+															time_dim->fd.id,
+															LockTupleExclusive,
+															RowShareLock);
+
+	if (!slice)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INTERNAL_ERROR),
+				errmsg("could not find time dimension slice for chunk %d", osm_chunk_id));
+	}
+
+	ts_cache_release(&hcache);
+
+	PG_RETURN_VOID();
+}
+
 TSDLLEXPORT bool
 ts_hypertable_has_continuous_aggregates(int32 hypertable_id)
 {

tsl/test/expected/chunk_utils_internal.out

@@ -498,11 +498,18 @@ SELECT status FROM _timescaledb_catalog.hypertable WHERE table_name = 'ht_try';
       3
 
 -- must also update the range since the created chunk contains data
+BEGIN;
+SELECT _timescaledb_functions.lock_osm_chunk_dimension_slice('ht_try');
+ lock_osm_chunk_dimension_slice 
+--------------------------------
+ 
+
 SELECT _timescaledb_functions.hypertable_osm_range_update('ht_try', '2020-01-01'::timestamptz, '2020-01-02');
  hypertable_osm_range_update 
 -----------------------------
  f
 
+COMMIT;
 -- OSM chunk is not visible in chunks view
 SELECT chunk_name, range_start, range_end
 FROM timescaledb_information.chunks
@@ -659,6 +666,11 @@ SELECT * FROM hypertable_approximate_size('ht_try');
 -----------------------------
                        32768
 
+\set ON_ERROR_STOP 0
+-- Error for a hypertable that has no OSM chunk
+SELECT _timescaledb_functions.lock_osm_chunk_dimension_slice('test1.hyper1');
+ERROR:  no OSM chunk found for hypertable test1.hyper1
+\set ON_ERROR_STOP 1
 --TEST GUC variable to enable/disable OSM chunk
 SET timescaledb.enable_tiered_reads=false;
 :EXPLAIN SELECT * from ht_try;

tsl/test/isolation/expected/osm_range_updates_iso.out

@@ -1,19 +1,34 @@
-Parsed test spec with 10 sessions
+Parsed test spec with 11 sessions
+
+starting permutation: LockDimSliceTuple LockDimSliceTuple2 UnlockDimSliceTuple UnlockDimSliceTuple2
+step LockDimSliceTuple: 
+  BEGIN;
+  SELECT _timescaledb_functions.lock_osm_chunk_dimension_slice('osm_test');
+
+lock_osm_chunk_dimension_slice
+------------------------------
+                              
+
+step LockDimSliceTuple2: 
+  BEGIN;
+  SELECT _timescaledb_functions.lock_osm_chunk_dimension_slice('osm_test');
+ <waiting ...>
+step UnlockDimSliceTuple: ROLLBACK;
+step LockDimSliceTuple2: <... completed>
+lock_osm_chunk_dimension_slice
+------------------------------
+                              
+
+step UnlockDimSliceTuple2: ROLLBACK;
 
 starting permutation: LockDimSliceTuple UR1b UR1u UR2b UR2u UnlockDimSliceTuple UR1c UR2c
 step LockDimSliceTuple: 
   BEGIN;
-  SELECT range_start, range_end FROM _timescaledb_catalog.dimension_slice
-  WHERE id IN ( SELECT ds.id FROM
-    _timescaledb_catalog.chunk ch,
-    _timescaledb_catalog.dimension_slice ds, _timescaledb_catalog.hypertable ht
-    WHERE ht.table_name like 'osm_test' AND ds.chunk_id = ch.id AND ht.id = ch.hypertable_id
-    AND ch.osm_chunk = true
-    ) FOR UPDATE;
-
-        range_start|          range_end
--------------------+-------------------
-9223372036854775806|9223372036854775807
+  SELECT _timescaledb_functions.lock_osm_chunk_dimension_slice('osm_test');
+
+lock_osm_chunk_dimension_slice
+------------------------------
+                              
 
 step UR1b: BEGIN;
 step UR1u: SELECT _timescaledb_functions.hypertable_osm_range_update('osm_test', 0, 10); <waiting ...>
@@ -36,17 +51,11 @@ step UR2c: COMMIT;
 starting permutation: LockDimSliceTuple DTb UR1b DropOsmChunk UR1u UnlockDimSliceTuple DTc UR1c
 step LockDimSliceTuple: 
   BEGIN;
-  SELECT range_start, range_end FROM _timescaledb_catalog.dimension_slice
-  WHERE id IN ( SELECT ds.id FROM
-    _timescaledb_catalog.chunk ch,
-    _timescaledb_catalog.dimension_slice ds, _timescaledb_catalog.hypertable ht
-    WHERE ht.table_name like 'osm_test' AND ds.chunk_id = ch.id AND ht.id = ch.hypertable_id
-    AND ch.osm_chunk = true
-    ) FOR UPDATE;
-
-        range_start|          range_end
--------------------+-------------------
-9223372036854775806|9223372036854775807
+  SELECT _timescaledb_functions.lock_osm_chunk_dimension_slice('osm_test');
+
+lock_osm_chunk_dimension_slice
+------------------------------
+                              
 
 step DTb: BEGIN;
 step UR1b: BEGIN;
@@ -73,17 +82,11 @@ step UR1c: COMMIT;
 starting permutation: LockDimSliceTuple DTb UR1b UR1u DropOsmChunk UnlockDimSliceTuple UR1c DTc
 step LockDimSliceTuple: 
   BEGIN;
-  SELECT range_start, range_end FROM _timescaledb_catalog.dimension_slice
-  WHERE id IN ( SELECT ds.id FROM
-    _timescaledb_catalog.chunk ch,
-    _timescaledb_catalog.dimension_slice ds, _timescaledb_catalog.hypertable ht
-    WHERE ht.table_name like 'osm_test' AND ds.chunk_id = ch.id AND ht.id = ch.hypertable_id
-    AND ch.osm_chunk = true
-    ) FOR UPDATE;
-
-        range_start|          range_end
--------------------+-------------------
-9223372036854775806|9223372036854775807
+  SELECT _timescaledb_functions.lock_osm_chunk_dimension_slice('osm_test');
+
+lock_osm_chunk_dimension_slice
+------------------------------
+                              
 
 step DTb: BEGIN;
 step UR1b: BEGIN;

tsl/test/isolation/specs/osm_range_updates_iso.spec

@@ -45,16 +45,18 @@ step "UR2c" { COMMIT; }
 session "LDST"
 step "LockDimSliceTuple" {
   BEGIN;
-  SELECT range_start, range_end FROM _timescaledb_catalog.dimension_slice
-  WHERE id IN ( SELECT ds.id FROM
-    _timescaledb_catalog.chunk ch,
-    _timescaledb_catalog.dimension_slice ds, _timescaledb_catalog.hypertable ht
-    WHERE ht.table_name like 'osm_test' AND ds.chunk_id = ch.id AND ht.id = ch.hypertable_id
-    AND ch.osm_chunk = true
-    ) FOR UPDATE;
+  SELECT _timescaledb_functions.lock_osm_chunk_dimension_slice('osm_test');
   }
 step "UnlockDimSliceTuple" { ROLLBACK; }
 
+# second session that locks the same dimension_slice tuple
+session "LDST2"
+step "LockDimSliceTuple2" {
+  BEGIN;
+  SELECT _timescaledb_functions.lock_osm_chunk_dimension_slice('osm_test');
+  }
+step "UnlockDimSliceTuple2" { ROLLBACK; }
+
 session "DT"
 step "DTb" { BEGIN; }
 step "DropOsmChunk" {
@@ -102,6 +104,10 @@ step DR2b { BEGIN; }
 step DR2drop { SELECT _timescaledb_functions.drop_osm_chunk('test_drop'); }
 step DR2c { COMMIT; }
 
+# Two concurrent locks on the same OSM chunk dimension_slice tuple block one
+# another. The second lock can only be acquired after the first session rolls
+# back and releases its lock.
+permutation "LockDimSliceTuple" "LockDimSliceTuple2" "UnlockDimSliceTuple" "UnlockDimSliceTuple2"
 # Concurrent updates will block one another
 # this previously deadlocked one of the two transactions
 permutation "LockDimSliceTuple" "UR1b" "UR1u" "UR2b" "UR2u" "UnlockDimSliceTuple" "UR1c" "UR2c"

tsl/test/shared/expected/extension.out

@@ -91,6 +91,7 @@ ORDER BY pronamespace::regnamespace::text COLLATE "C", p.oid::regprocedure::text
  _timescaledb_functions.jsonb_get_matching_index_entry(jsonb,text,text)
  _timescaledb_functions.last_combinefunc(internal,internal)
  _timescaledb_functions.last_sfunc(internal,anyelement,"any")
+ _timescaledb_functions.lock_osm_chunk_dimension_slice(regclass)
  _timescaledb_functions.make_multirange_from_internal_time(tsrange,bigint,bigint)
  _timescaledb_functions.make_multirange_from_internal_time(tstzrange,bigint,bigint)
  _timescaledb_functions.make_range_from_internal_time(anyrange,anyelement,anyelement)

tsl/test/sql/chunk_utils_internal.sql

@@ -339,7 +339,10 @@ SELECT _timescaledb_functions.attach_osm_table_chunk('ht_try', 'child_fdw_table'
 -- check hypertable status
 SELECT status FROM _timescaledb_catalog.hypertable WHERE table_name = 'ht_try';
 -- must also update the range since the created chunk contains data
+BEGIN;
+SELECT _timescaledb_functions.lock_osm_chunk_dimension_slice('ht_try');
 SELECT _timescaledb_functions.hypertable_osm_range_update('ht_try', '2020-01-01'::timestamptz, '2020-01-02');
+COMMIT;
 
 -- OSM chunk is not visible in chunks view
 SELECT chunk_name, range_start, range_end
@@ -406,6 +409,11 @@ SELECT _timescaledb_functions.hypertable_osm_range_update('ht_try', '2022-05-05
 -- test that approximate size function works when a osm chunk is present
 SELECT * FROM hypertable_approximate_size('ht_try');
 
+\set ON_ERROR_STOP 0
+-- Error for a hypertable that has no OSM chunk
+SELECT _timescaledb_functions.lock_osm_chunk_dimension_slice('test1.hyper1');
+\set ON_ERROR_STOP 1
+
 --TEST GUC variable to enable/disable OSM chunk
 SET timescaledb.enable_tiered_reads=false;
 :EXPLAIN SELECT * from ht_try;