Add cache for relation persistence

pgxn/neon/Makefile

@@ -19,6 +19,7 @@ OBJS = \
 	neon_walreader.o \
 	pagestore_smgr.o \
 	relsize_cache.o \
+	relperst_cache.o \
 	unstable_extensions.o \
 	walproposer.o \
 	walproposer_pg.o \

pgxn/neon/neon.c

@@ -489,6 +489,7 @@ _PG_init(void)
 	/* Stage 1: Define GUCs, and other early intialization */
 	pg_init_libpagestore();
 	relsize_hash_init();
+	relperst_hash_init();
 	lfc_init();
 	pg_init_walproposer();
 	init_lwlsncache();
@@ -722,6 +723,7 @@ neon_shmem_request_hook(void)
 	NeonPerfCountersShmemRequest();
 	PagestoreShmemRequest();
 	RelsizeCacheShmemRequest();
+	RelperstCacheShmemRequest();
 	WalproposerShmemRequest();
 	LwLsnCacheShmemRequest();
 }
@@ -744,6 +746,7 @@ neon_shmem_startup_hook(void)
 	NeonPerfCountersShmemInit();
 	PagestoreShmemInit();
 	RelsizeCacheShmemInit();
+	RelperstCacheShmemInit();
 	WalproposerShmemInit();
 	LwLsnCacheShmemInit();
 

pgxn/neon/neon.h

@@ -74,13 +74,15 @@ extern PGDLLEXPORT void LogicalSlotsMonitorMain(Datum main_arg);
 extern void LfcShmemRequest(void);
 extern void PagestoreShmemRequest(void);
 extern void RelsizeCacheShmemRequest(void);
+extern void RelperstCacheShmemRequest(void);
 extern void WalproposerShmemRequest(void);
 extern void LwLsnCacheShmemRequest(void);
 extern void NeonPerfCountersShmemRequest(void);
 
 extern void LfcShmemInit(void);
 extern void PagestoreShmemInit(void);
 extern void RelsizeCacheShmemInit(void);
+extern void RelperstCacheShmemInit(void);
 extern void WalproposerShmemInit(void);
 extern void LwLsnCacheShmemInit(void);
 extern void NeonPerfCountersShmemInit(void);

pgxn/neon/pagestore_client.h

@@ -298,4 +298,50 @@ extern void set_cached_relsize(NRelFileInfo rinfo, ForkNumber forknum, BlockNumb
 extern void update_cached_relsize(NRelFileInfo rinfo, ForkNumber forknum, BlockNumber size);
 extern void forget_cached_relsize(NRelFileInfo rinfo, ForkNumber forknum);
 
+/*
+ * Relation persistence enum.
+ */
+typedef enum
+{
+    /* The persistence is not known */
+	NEON_RELPERSISTENCE_UNKNOWN,
+
+    /* The relation is a permanent relation that is WAL-logged normally */
+	NEON_RELPERSISTENCE_PERMANENT,
+
+    /* The relation is an unlogged table/index, stored only on local disk */
+	NEON_RELPERSISTENCE_UNLOGGED,
+
+    /*
+     * The relation is a permanent (index) relation, but it is being built by an in-progress
+     * transaction. It currently only lives on local disk and hasn't been WAL-logged yet.
+     * It will turn into a permanent relation later when the index build completes.
+     * This is currently used for GiST, SP-GiST and GIN indexes, as well as the pgvector
+     * extension.
+     */
+	NEON_RELPERSISTENCE_UNLOGGED_BUILD
+} NeonRelPersistence;
+
+/*
+ * Entry type stored in relperst_hash. We have just one entry for the whole relation, i.e. we don't have separate entries for the individual forks.
+ * It gets a little complicated with unlogged relations. The main fork of an unlogged relation is considered UNLOGGED, but its init-fork is
+ * treated as PERMANENT. It is specially checked in neon_write.
+ */
+typedef struct
+{
+	NRelFileInfo rel;
+	uint8		relperst;		/* See NeonRelPersistence */
+	uint16		access_count;
+	dlist_node	lru_node;	/* LRU list node */
+} NeonRelPersistenceEntry;
+
+extern LWLockId finish_unlogged_build_lock;
+
+extern void relperst_hash_init(void);
+extern void set_cached_relperst(NRelFileInfo rinfo, NeonRelPersistence relperst);
+extern NeonRelPersistence get_cached_relperst(NRelFileInfo rinfo);
+extern NeonRelPersistenceEntry* pin_cached_relperst(NRelFileInfo rinfo, NeonRelPersistence relperst);
+extern void unpin_cached_relperst(NeonRelPersistenceEntry* entry);
+extern void forget_cached_relperst(NRelFileInfo rinfo);
+
 #endif							/* PAGESTORE_CLIENT_H */