!874 add smgr cached nblocks for main fork

Merge pull request !874 from LiHeng/cachedNblock

src/common/backend/catalog/storage.cpp

@@ -687,6 +687,7 @@ void RelationTruncate(Relation rel, BlockNumber nblocks)
     rel->rd_smgr->smgr_targblock = InvalidBlockNumber;
     rel->rd_smgr->smgr_fsm_nblocks = InvalidBlockNumber;
     rel->rd_smgr->smgr_vm_nblocks = InvalidBlockNumber;
+    rel->rd_smgr->smgr_cached_nblocks = InvalidBlockNumber;
 
     for (int i = 0; i < rel->rd_smgr->smgr_bcmarry_size; i++)
         rel->rd_smgr->smgr_bcm_nblocks[i] = InvalidBlockNumber;

src/gausskernel/storage/buffer/bufmgr.cpp

@@ -2030,9 +2030,16 @@ static Buffer ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumb
      */
 #ifndef ENABLE_MULTIPLE_NODES
     } else if (RecoveryInProgress()) {
-        if (blockNum >= smgrnblocks(smgr, forkNum))
-            return InvalidBuffer;
+        BlockNumber totalBlkNum = smgrnblocks_cached(smgr, forkNum);
 
+        /* Update cached blocks */
+        if (totalBlkNum == InvalidBlockNumber || blockNum >= totalBlkNum) {
+            totalBlkNum = smgrnblocks(smgr, forkNum);
+        }
+
+        if (blockNum >= totalBlkNum) {
+            return InvalidBuffer;
+        }
 #endif
     }
 

src/gausskernel/storage/smgr/smgr.cpp

@@ -150,6 +150,7 @@ static void _smgr_init(SMgrRelation reln, int col = 0)
     reln->smgr_targblock = InvalidBlockNumber;
     reln->smgr_fsm_nblocks = InvalidBlockNumber;
     reln->smgr_vm_nblocks = InvalidBlockNumber;
+    reln->smgr_cached_nblocks = InvalidBlockNumber;
 
     reln->smgr_which = 0; /* we only have md.c at present */
 
@@ -809,7 +810,36 @@ void smgrwriteback(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
  */
 BlockNumber smgrnblocks(SMgrRelation reln, ForkNumber forknum)
 {
-    return (*(smgrsw[reln->smgr_which].smgr_nblocks))(reln, forknum);
+    BlockNumber result = InvalidBlockNumber;
+
+    result = (*(smgrsw[reln->smgr_which].smgr_nblocks))(reln, forknum);
+    if (forknum == MAIN_FORKNUM) {
+        reln->smgr_cached_nblocks = result;
+    }
+
+    return result;
+}
+
+/*
+ * smgrnblocks_cached() -- Get the cached number of blocks in the supplied
+ *                          relation.
+ *
+ * Returns an InvalidBlockNumber when not in recovery and when the relation
+ * fork size is not cached. Now, we only support cache main fork.
+ */
+BlockNumber
+smgrnblocks_cached(SMgrRelation reln, ForkNumber forknum)
+{
+    /*
+     * For now, we only use cached values in recovery due to lack of a shared
+     * invalidation mechanism for changes in file size.
+     */
+    if (RecoveryInProgress() && forknum == MAIN_FORKNUM &&
+        reln->smgr_cached_nblocks != InvalidBlockNumber) {
+        return reln->smgr_cached_nblocks;
+    }
+
+    return InvalidBlockNumber;
 }
 
 void smgrtruncatefunc(SMgrRelation reln, ForkNumber forknum, BlockNumber nblocks)
@@ -839,6 +869,9 @@ void smgrtruncate(SMgrRelation reln, ForkNumber forknum, BlockNumber nblocks)
     if (forknum == BCM_FORKNUM)
         BCMArrayDropAllBlocks(reln->smgr_rnode.node);
 
+    /* Make the cached size is invalid if we encounter an error. */
+    reln->smgr_cached_nblocks = InvalidBlockNumber;
+
     /*
      * Send a shared-inval message to force other backends to close any smgr
      * references they may have for this rel.  This is useful because they

src/include/storage/smgr.h

@@ -60,6 +60,7 @@ typedef struct SMgrRelationData {
     BlockNumber smgr_targblock;   /* current insertion target block */
     BlockNumber smgr_fsm_nblocks; /* last known size of fsm fork */
     BlockNumber smgr_vm_nblocks;  /* last known size of vm fork */
+    BlockNumber smgr_cached_nblocks; /* last known size of main fork*/
 
     int smgr_bcmarry_size;
     BlockNumber* smgr_bcm_nblocks; /* last known size of bcm fork */
@@ -106,6 +107,7 @@ extern void smgrread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum
 extern void smgrwrite(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, const char* buffer, bool skipFsync);
 extern void smgrwriteback(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, BlockNumber nblocks);
 extern BlockNumber smgrnblocks(SMgrRelation reln, ForkNumber forknum);
+extern BlockNumber smgrnblocks_cached(SMgrRelation reln, ForkNumber forknum);
 extern void smgrtruncatefunc(SMgrRelation reln, ForkNumber forknum, BlockNumber nblocks);
 extern void smgrtruncate(SMgrRelation reln, ForkNumber forknum, BlockNumber nblocks);
 extern void smgrimmedsync(SMgrRelation reln, ForkNumber forknum);