Improve notation of BuiltinTrancheNames

Use C99 designated initializer syntax for array elements, instead of
writing the position in a comment.  This is less verbose and much more
readable.  Akin to cc150596341e.

One disadvantage is that the BuiltinTrancheNames array now has a hole of
51 NULLs -- previously, the array elements were shifted 51 elements
 downward to avoid this.  This can be fixed by merging the
IndividualLWLockNames array into BuiltinTrancheNames, which would occupy
those 51 pointers, but because it requires some arguably ugly Meson
hackery, it's left for later.

Discussion: https://postgr.es/m/202401231025.gbv4nnte5fmm@alvherre.pgsql

diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index 2f2de5a5624c6b6d5f1384771d768f81223e4dad..98fa6035cc546f4e89326fbfb0f57adaddd33df4 100644 (file)
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -132,72 +132,41 @@ StaticAssertDecl(LW_VAL_EXCLUSIVE > (uint32) MAX_BACKENDS,
 extern const char *const IndividualLWLockNames[];  /* in lwlocknames.c */
 
 static const char *const BuiltinTrancheNames[] = {
-   /* LWTRANCHE_XACT_BUFFER: */
-   "XactBuffer",
-   /* LWTRANCHE_COMMITTS_BUFFER: */
-   "CommitTsBuffer",
-   /* LWTRANCHE_SUBTRANS_BUFFER: */
-   "SubtransBuffer",
-   /* LWTRANCHE_MULTIXACTOFFSET_BUFFER: */
-   "MultiXactOffsetBuffer",
-   /* LWTRANCHE_MULTIXACTMEMBER_BUFFER: */
-   "MultiXactMemberBuffer",
-   /* LWTRANCHE_NOTIFY_BUFFER: */
-   "NotifyBuffer",
-   /* LWTRANCHE_SERIAL_BUFFER: */
-   "SerialBuffer",
-   /* LWTRANCHE_WAL_INSERT: */
-   "WALInsert",
-   /* LWTRANCHE_BUFFER_CONTENT: */
-   "BufferContent",
-   /* LWTRANCHE_REPLICATION_ORIGIN_STATE: */
-   "ReplicationOriginState",
-   /* LWTRANCHE_REPLICATION_SLOT_IO: */
-   "ReplicationSlotIO",
-   /* LWTRANCHE_LOCK_FASTPATH: */
-   "LockFastPath",
-   /* LWTRANCHE_BUFFER_MAPPING: */
-   "BufferMapping",
-   /* LWTRANCHE_LOCK_MANAGER: */
-   "LockManager",
-   /* LWTRANCHE_PREDICATE_LOCK_MANAGER: */
-   "PredicateLockManager",
-   /* LWTRANCHE_PARALLEL_HASH_JOIN: */
-   "ParallelHashJoin",
-   /* LWTRANCHE_PARALLEL_QUERY_DSA: */
-   "ParallelQueryDSA",
-   /* LWTRANCHE_PER_SESSION_DSA: */
-   "PerSessionDSA",
-   /* LWTRANCHE_PER_SESSION_RECORD_TYPE: */
-   "PerSessionRecordType",
-   /* LWTRANCHE_PER_SESSION_RECORD_TYPMOD: */
-   "PerSessionRecordTypmod",
-   /* LWTRANCHE_SHARED_TUPLESTORE: */
-   "SharedTupleStore",
-   /* LWTRANCHE_SHARED_TIDBITMAP: */
-   "SharedTidBitmap",
-   /* LWTRANCHE_PARALLEL_APPEND: */
-   "ParallelAppend",
-   /* LWTRANCHE_PER_XACT_PREDICATE_LIST: */
-   "PerXactPredicateList",
-   /* LWTRANCHE_PGSTATS_DSA: */
-   "PgStatsDSA",
-   /* LWTRANCHE_PGSTATS_HASH: */
-   "PgStatsHash",
-   /* LWTRANCHE_PGSTATS_DATA: */
-   "PgStatsData",
-   /* LWTRANCHE_LAUNCHER_DSA: */
-   "LogicalRepLauncherDSA",
-   /* LWTRANCHE_LAUNCHER_HASH: */
-   "LogicalRepLauncherHash",
-   /* LWTRANCHE_DSM_REGISTRY_DSA: */
-   "DSMRegistryDSA",
-   /* LWTRANCHE_DSM_REGISTRY_HASH: */
-   "DSMRegistryHash",
+   [LWTRANCHE_XACT_BUFFER] = "XactBuffer",
+   [LWTRANCHE_COMMITTS_BUFFER] = "CommitTsBuffer",
+   [LWTRANCHE_SUBTRANS_BUFFER] = "SubtransBuffer",
+   [LWTRANCHE_MULTIXACTOFFSET_BUFFER] = "MultiXactOffsetBuffer",
+   [LWTRANCHE_MULTIXACTMEMBER_BUFFER] = "MultiXactMemberBuffer",
+   [LWTRANCHE_NOTIFY_BUFFER] = "NotifyBuffer",
+   [LWTRANCHE_SERIAL_BUFFER] = "SerialBuffer",
+   [LWTRANCHE_WAL_INSERT] = "WALInsert",
+   [LWTRANCHE_BUFFER_CONTENT] = "BufferContent",
+   [LWTRANCHE_REPLICATION_ORIGIN_STATE] = "ReplicationOriginState",
+   [LWTRANCHE_REPLICATION_SLOT_IO] = "ReplicationSlotIO",
+   [LWTRANCHE_LOCK_FASTPATH] = "LockFastPath",
+   [LWTRANCHE_BUFFER_MAPPING] = "BufferMapping",
+   [LWTRANCHE_LOCK_MANAGER] = "LockManager",
+   [LWTRANCHE_PREDICATE_LOCK_MANAGER] = "PredicateLockManager",
+   [LWTRANCHE_PARALLEL_HASH_JOIN] = "ParallelHashJoin",
+   [LWTRANCHE_PARALLEL_QUERY_DSA] = "ParallelQueryDSA",
+   [LWTRANCHE_PER_SESSION_DSA] = "PerSessionDSA",
+   [LWTRANCHE_PER_SESSION_RECORD_TYPE] = "PerSessionRecordType",
+   [LWTRANCHE_PER_SESSION_RECORD_TYPMOD] = "PerSessionRecordTypmod",
+   [LWTRANCHE_SHARED_TUPLESTORE] = "SharedTupleStore",
+   [LWTRANCHE_SHARED_TIDBITMAP] = "SharedTidBitmap",
+   [LWTRANCHE_PARALLEL_APPEND] = "ParallelAppend",
+   [LWTRANCHE_PER_XACT_PREDICATE_LIST] = "PerXactPredicateList",
+   [LWTRANCHE_PGSTATS_DSA] = "PgStatsDSA",
+   [LWTRANCHE_PGSTATS_HASH] = "PgStatsHash",
+   [LWTRANCHE_PGSTATS_DATA] = "PgStatsData",
+   [LWTRANCHE_LAUNCHER_DSA] = "LogicalRepLauncherDSA",
+   [LWTRANCHE_LAUNCHER_HASH] = "LogicalRepLauncherHash",
+   [LWTRANCHE_DSM_REGISTRY_DSA] = "DSMRegistryDSA",
+   [LWTRANCHE_DSM_REGISTRY_HASH] = "DSMRegistryHash",
 };
 
 StaticAssertDecl(lengthof(BuiltinTrancheNames) ==
-                LWTRANCHE_FIRST_USER_DEFINED - NUM_INDIVIDUAL_LWLOCKS,
+                LWTRANCHE_FIRST_USER_DEFINED,
                 "missing entries in BuiltinTrancheNames[]");
 
 /*
@@ -775,7 +744,7 @@ GetLWTrancheName(uint16 trancheId)
 
    /* Built-in tranche? */
    if (trancheId < LWTRANCHE_FIRST_USER_DEFINED)
-       return BuiltinTrancheNames[trancheId - NUM_INDIVIDUAL_LWLOCKS];
+       return BuiltinTrancheNames[trancheId];
 
    /*
     * It's an extension tranche, so look in LWLockTrancheNames[].  However,