Ledger API to retrieve last block

Passing math.MaxUint64 to GetBlockByNumber()
will return the last block.

Change-Id: I110271ee6159544f7da216d2337271ea2aac23ff
Signed-off-by: denyeart <[email protected]>

Author: denyeart

core/ledger/blkstorage/blockstorage.go

@@ -55,7 +55,7 @@ type BlockStore interface {
 	GetBlockchainInfo() (*pb.BlockchainInfo, error)
 	RetrieveBlocks(startNum uint64) (ledger.ResultsIterator, error)
 	RetrieveBlockByHash(blockHash []byte) (*common.Block, error)
-	RetrieveBlockByNumber(blockNum uint64) (*common.Block, error)
+	RetrieveBlockByNumber(blockNum uint64) (*common.Block, error) // blockNum of  math.MaxUint64 will return last block
 	RetrieveTxByID(txID string) (*pb.Transaction, error)
 	Shutdown()
 }

core/ledger/blkstorage/fsblkstorage/blockfile_mgr.go

@@ -18,6 +18,7 @@ package fsblkstorage
 
 import (
 	"fmt"
+	"math"
 	"sync"
 	"sync/atomic"
 
@@ -412,6 +413,12 @@ func (mgr *blockfileMgr) retrieveBlockByHash(blockHash []byte) (*common.Block, e
 
 func (mgr *blockfileMgr) retrieveBlockByNumber(blockNum uint64) (*common.Block, error) {
 	logger.Debugf("retrieveBlockByNumber() - blockNum = [%d]", blockNum)
+
+	// interpret math.MaxUint64 as a request for last block
+	if blockNum == math.MaxUint64 {
+		blockNum = mgr.getBlockchainInfo().Height
+	}
+
 	loc, err := mgr.index.getBlockLocByBlockNum(blockNum)
 	if err != nil {
 		return nil, err

core/ledger/blkstorage/fsblkstorage/pkg_test.go

@@ -18,6 +18,7 @@ package fsblkstorage
 
 import (
 	"fmt"
+	"math"
 	"os"
 	"testing"
 
@@ -82,6 +83,11 @@ func (w *testBlockfileMgrWrapper) testGetBlockByNumber(blocks []*common.Block, s
 		testutil.AssertNoError(w.t, err, fmt.Sprintf("Error while retrieving [%d]th block from blockfileMgr", i))
 		testutil.AssertEquals(w.t, b, blocks[i])
 	}
+	// test getting the last block
+	b, err := w.blockfileMgr.retrieveBlockByNumber(math.MaxUint64)
+	iLastBlock := len(blocks) - 1
+	testutil.AssertNoError(w.t, err, fmt.Sprintf("Error while retrieving last block from blockfileMgr"))
+	testutil.AssertEquals(w.t, b, blocks[iLastBlock])
 }
 
 func (w *testBlockfileMgrWrapper) close() {

core/ledger/kvledger/kv_ledger.go

@@ -109,6 +109,7 @@ func (l *KVLedger) GetBlockchainInfo() (*pb.BlockchainInfo, error) {
 }
 
 // GetBlockByNumber returns block at a given height
+// blockNumber of  math.MaxUint64 will return last block
 func (l *KVLedger) GetBlockByNumber(blockNumber uint64) (*common.Block, error) {
 	return l.blockStore.RetrieveBlockByNumber(blockNumber)
 

core/ledger/ledger_interface.go

@@ -25,7 +25,8 @@ import (
 type Ledger interface {
 	// GetBlockchainInfo returns basic info about blockchain
 	GetBlockchainInfo() (*pb.BlockchainInfo, error)
-	// GetBlockchainInfo returns block at a given height
+	// GetBlockByNumber returns block at a given height
+	// blockNumber of  math.MaxUint64 will return last block
 	GetBlockByNumber(blockNumber uint64) (*common.Block, error)
 	// GetBlocksIterator returns an iterator that starts from `startBlockNumber`(inclusive).
 	// The iterator is a blocking iterator i.e., it blocks till the next block gets available in the ledger