Index sync up fix: skip first block if already indexed

https://jira.hyperledger.org/browse/FAB-2054

Starting block storage after a crash may kick off indexing
the blocks that may have been committed to storage but left out
from indexing. The first block can be skipped as this is the block
we get reference to from index itself (hence already indexed).

Change-Id: Ic96bf581e05e395ab19ec80bfe131071fb6ecc67
Signed-off-by: manish <[email protected]>

Author: manish-sethi

common/ledger/blkstorage/fsblkstorage/blockfile_mgr.go

@@ -320,6 +320,7 @@ func (mgr *blockfileMgr) syncIndex() error {
 	startFileNum := 0
 	startOffset := 0
 	blockNum := uint64(1)
+	skipFirstBlock := false
 	//get the last file that blocks were added to using the checkpoint info
 	endFileNum := mgr.cpInfo.latestFileChunkSuffixNum
 	//if the index stored in the db has value, update the index information with those values
@@ -331,6 +332,7 @@ func (mgr *blockfileMgr) syncIndex() error {
 		startFileNum = flp.fileSuffixNum
 		startOffset = flp.locPointer.offset
 		blockNum = lastBlockIndexed
+		skipFirstBlock = true
 	}
 
 	//open a blockstream to the file location that was stored in the index
@@ -341,6 +343,16 @@ func (mgr *blockfileMgr) syncIndex() error {
 	var blockBytes []byte
 	var blockPlacementInfo *blockPlacementInfo
 
+	if skipFirstBlock {
+		if blockBytes, _, err = stream.nextBlockBytesAndPlacementInfo(); err != nil {
+			return err
+		}
+		if blockBytes == nil {
+			return fmt.Errorf("block bytes for block num = [%d] should not be nil here. The indexes for the block are already present",
+				lastBlockIndexed)
+		}
+	}
+
 	//Should be at the last block, but go ahead and loop looking for next blockBytes
 	//If there is another block, add it to the index
 	for {