Fix mistyping in test comments

pgxn/neon/file_cache.c

@@ -694,7 +694,7 @@ lfc_readv_select(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
 	{
 		struct iovec iov[PG_IOV_MAX];
 		int		chunk_offs = blkno & (BLOCKS_PER_CHUNK - 1);
-		int		blocks_in_chunk = Min(nblocks, BLOCKS_PER_CHUNK - (blkno % BLOCKS_PER_CHUNK));
+		int		blocks_in_chunk = Min(nblocks, BLOCKS_PER_CHUNK - chunk_offs);
 		int		iteration_hits = 0;
 		int		iteration_misses = 0;
 		uint64	io_time_us = 0;
@@ -708,10 +708,13 @@ lfc_readv_select(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
 			n_blocks_to_read += (BITMAP_ISSET(mask, buf_offset + i) != 0);
 			iov[i].iov_base = buffers[buf_offset + i];
 			iov[i].iov_len = BLCKSZ;
-			BITMAP_CLR(mask,  buf_offset + i);
 		}
 		if (n_blocks_to_read == 0)
 		{
+			for (int i = 0; i < blocks_in_chunk; i++)
+			{
+				BITMAP_CLR(mask, buf_offset + i);
+			}
 			buf_offset += blocks_in_chunk;
 			nblocks -= blocks_in_chunk;
 			blkno += blocks_in_chunk;
@@ -744,6 +747,10 @@ lfc_readv_select(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
 		if (entry == NULL)
 		{
 			/* Pages are not cached */
+			for (int i = 0; i < blocks_in_chunk; i++)
+			{
+				BITMAP_CLR(mask, buf_offset + i);
+			}
 			lfc_ctl->misses += blocks_in_chunk;
 			pgBufferUsage.file_cache.misses += blocks_in_chunk;
 			LWLockRelease(lfc_lock);
@@ -766,6 +773,10 @@ lfc_readv_select(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
 		{
 			FileCacheBlockState state = UNAVAILABLE;
 			bool sleeping = false;
+
+			if (!BITMAP_ISSET(mask, buf_offset + i))
+				continue;
+
 			while (lfc_ctl->generation == generation)
 			{
 				state = GET_STATE(entry, chunk_offs + i);
@@ -789,11 +800,13 @@ lfc_readv_select(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
 			}
 			if (state == AVAILABLE)
 			{
-				BITMAP_SET(mask, buf_offset + i);
 				iteration_hits++;
 			}
 			else
+			{
+				BITMAP_CLR(mask, buf_offset + i);
 				iteration_misses++;
+			}
 		}
 		LWLockRelease(lfc_lock);
 
@@ -801,15 +814,36 @@ lfc_readv_select(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
 
 		if (iteration_hits != 0)
 		{
-			pgstat_report_wait_start(WAIT_EVENT_NEON_LFC_READ);
-			rc = preadv(lfc_desc, iov, blocks_in_chunk,
-						((off_t) entry_offset * BLOCKS_PER_CHUNK + chunk_offs) * BLCKSZ);
-			pgstat_report_wait_end();
-
-			if (rc != (BLCKSZ * blocks_in_chunk))
+			if (blocks_in_chunk == n_blocks_to_read)
 			{
-				lfc_disable("read");
-				return -1;
+				pgstat_report_wait_start(WAIT_EVENT_NEON_LFC_READ);
+				rc = preadv(lfc_desc, iov, blocks_in_chunk,
+							((off_t) entry_offset * BLOCKS_PER_CHUNK + chunk_offs) * BLCKSZ);
+				pgstat_report_wait_end();
+
+				if (rc != (BLCKSZ * blocks_in_chunk))
+				{
+					lfc_disable("read");
+					return -1;
+				}
+			}
+			else
+			{
+				/* Some blocks are already prefetched in provided buffers, we should not rewrite them, so we can not use vector read */
+				for (int i = 0; i < blocks_in_chunk; i++)
+				{
+					if (BITMAP_ISSET(mask, buf_offset + i))
+					{
+						pgstat_report_wait_start(WAIT_EVENT_NEON_LFC_READ);
+						rc = pread(lfc_desc, iov[i].iov_base, BLCKSZ, ((off_t) entry_offset * BLOCKS_PER_CHUNK + chunk_offs + i) * BLCKSZ);
+						pgstat_report_wait_end();
+						if (rc != BLCKSZ)
+						{
+							lfc_disable("read");
+							return -1;
+						}
+					}
+				}
 			}
 		}
 
@@ -1000,12 +1034,12 @@ lfc_prefetch(NRelFileInfo rinfo, ForkNumber forknum, BlockNumber blkno,
 		LWLockRelease(lfc_lock);
 		return false;
 	}
-	
+
 	lwlsn = neon_get_lwlsn(rinfo, forknum, blkno);
 
 	if (lwlsn > lsn)
 	{
-		elog(DEBUG1, "Skip LFC write for %d because LwLSN=%X/%X is greater than not_nodified_since LSN %X/%X",
+		elog(DEBUG1, "Skip LFC write for %d because LwLSN=%X/%X is greater than not_modified_since LSN %X/%X",
 			 blkno, LSN_FORMAT_ARGS(lwlsn), LSN_FORMAT_ARGS(lsn));
 		LWLockRelease(lfc_lock);
 		return false;

pgxn/neon/libpagestore.c

@@ -1142,37 +1142,23 @@ pageserver_try_receive(shardno_t shard_no)
 	NeonResponse *resp;
 	PageServer *shard = &page_servers[shard_no];
 	PGconn	   *pageserver_conn = shard->conn;
-	/* read response */
-	int			rc;
+	int	rc;
 
 	if (shard->state != PS_Connected)
 		return NULL;
 
 	Assert(pageserver_conn);
 
-	while (true)
+	rc = PQgetCopyData(shard->conn, &resp_buff.data, 1 /* async */);
+	if (rc == 0)
 	{
-		if (PQisBusy(shard->conn))
+		if (!PQconsumeInput(shard->conn))
 		{
-			WaitEvent	event;
-			if (WaitEventSetWait(shard->wes_read, 0, &event, 1,
-								 WAIT_EVENT_NEON_PS_READ) != 1
-				|| (event.events & WL_SOCKET_READABLE) == 0)
-			{
-				return NULL;
-			}
+			return NULL;
 		}
 		rc = PQgetCopyData(shard->conn, &resp_buff.data, 1 /* async */);
-		if (rc == 0)
-		{
-			if (!PQconsumeInput(shard->conn))
-			{
-				return NULL;
-			}
-		}
-		else
-			break;
 	}
+
 	if (rc == 0)
 		return NULL;
 	else if (rc > 0)

test_runner/regress/test_lfc_prefetch.py

@@ -97,5 +97,5 @@ def test_lfc_prefetch(neon_simple_env: NeonEnv):
     prefetch_expired = cur.fetchall()[0][0][0]["Plan"]["Prefetch Expired Requests"]
     log.info(f"Unused prefetches: {prefetch_expired}")
 
-    # No redundant prefethc requrests if prefetch results are stored in LFC
+    # No redundant prefetch requests if prefetch results are stored in LFC
     assert prefetch_expired == 0