fix GetLatestBlock() gRPC (pure block cache)

common/common.go

@@ -161,16 +161,11 @@ type (
 func FirstRPC() {
 	retryCount := 0
 	for {
-		result, rpcErr := RawRequest("getblockchaininfo", []json.RawMessage{})
-		if rpcErr == nil {
+		_, err := GetBlockChainInfo()
+		if err == nil {
 			if retryCount > 0 {
 				Log.Warn("getblockchaininfo RPC successful")
 			}
-			var getblockchaininfo ZcashdRpcReplyGetblockchaininfo
-			err := json.Unmarshal(result, &getblockchaininfo)
-			if err != nil {
-				Log.Fatalf("error parsing JSON getblockchaininfo response: %v", err)
-			}
 			break
 		}
 		retryCount++
@@ -180,13 +175,26 @@ func FirstRPC() {
 			}).Fatal("unable to issue getblockchaininfo RPC call to zcashd node")
 		}
 		Log.WithFields(logrus.Fields{
-			"error": rpcErr.Error(),
+			"error": err.Error(),
 			"retry": retryCount,
 		}).Warn("error with getblockchaininfo rpc, retrying...")
 		Time.Sleep(time.Duration(10+retryCount*5) * time.Second) // backoff
 	}
 }
 
+func GetBlockChainInfo() (*ZcashdRpcReplyGetblockchaininfo, error) {
+	result, rpcErr := RawRequest("getblockchaininfo", []json.RawMessage{})
+	if rpcErr != nil {
+		return nil, rpcErr
+	}
+	var getblockchaininfoReply ZcashdRpcReplyGetblockchaininfo
+	err := json.Unmarshal(result, &getblockchaininfoReply)
+	if err != nil {
+		return nil, err
+	}
+	return &getblockchaininfoReply, nil
+}
+
 func GetLightdInfo() (*walletrpc.LightdInfo, error) {
 	result, rpcErr := RawRequest("getinfo", []json.RawMessage{})
 	if rpcErr != nil {

common/darkside.go

@@ -405,13 +405,23 @@ func DarksideClearIncomingTransactions() {
 func darksideRawRequest(method string, params []json.RawMessage) (json.RawMessage, error) {
 	switch method {
 	case "getblockchaininfo":
+		state.mutex.RLock()
+		defer state.mutex.RUnlock()
+		if len(state.activeBlocks) == 0 {
+			Log.Fatal("getblockchaininfo: no blocks")
+		}
+		index := state.latestHeight - state.startHeight
+		block := parser.NewBlock()
+		block.ParseFromSlice(state.activeBlocks[index])
+		hash := hex.EncodeToString(block.GetDisplayHash())
 		blockchaininfo := &ZcashdRpcReplyGetblockchaininfo{
 			Chain: state.chainName,
 			Upgrades: map[string]Upgradeinfo{
 				"76b809bb": {ActivationHeight: state.startHeight},
 			},
-			Blocks:    state.latestHeight,
-			Consensus: ConsensusInfo{state.branchID, state.branchID},
+			Blocks:        state.latestHeight,
+			Consensus:     ConsensusInfo{state.branchID, state.branchID},
+			BestBlockHash: hash,
 		}
 		return json.Marshal(blockchaininfo)
 

common/mempool.go

@@ -46,7 +46,7 @@ func GetMempool(sendToClient func(*walletrpc.RawTransaction) error) error {
 		// Don't fetch the mempool more often than every 2 seconds.
 		now := Time.Now()
 		if now.After(g_lastTime.Add(2 * time.Second)) {
-			blockChainInfo, err := getLatestBlockChainInfo()
+			blockChainInfo, err := GetBlockChainInfo()
 			if err != nil {
 				g_lock.Unlock()
 				return err
@@ -137,16 +137,3 @@ func refreshMempoolTxns() error {
 	}
 	return nil
 }
-
-func getLatestBlockChainInfo() (*ZcashdRpcReplyGetblockchaininfo, error) {
-	result, rpcErr := RawRequest("getblockchaininfo", []json.RawMessage{})
-	if rpcErr != nil {
-		return nil, rpcErr
-	}
-	var getblockchaininfoReply ZcashdRpcReplyGetblockchaininfo
-	err := json.Unmarshal(result, &getblockchaininfoReply)
-	if err != nil {
-		return nil, err
-	}
-	return &getblockchaininfoReply, nil
-}

frontend/service.go

@@ -62,14 +62,15 @@ func (s *lwdStreamer) GetLatestBlock(ctx context.Context, placeholder *walletrpc
 	// Lock to ensure we return consistent height and hash
 	s.mutex.Lock()
 	defer s.mutex.Unlock()
-	latestBlock := s.cache.GetLatestHeight()
-
-	if latestBlock == -1 {
-		return nil, errors.New("cache is empty, server is probably not yet ready")
+	blockChainInfo, err := common.GetBlockChainInfo()
+	if err != nil {
+		return nil, err
 	}
-	latestHash := s.cache.GetLatestHash()
-
-	return &walletrpc.BlockID{Height: uint64(latestBlock), Hash: latestHash}, nil
+	bestBlockHash, err := hex.DecodeString(blockChainInfo.BestBlockHash)
+	if err != nil {
+		return nil, err
+	}
+	return &walletrpc.BlockID{Height: uint64(blockChainInfo.Blocks), Hash: []byte(bestBlockHash)}, nil
 }
 
 // GetTaddressTxids is a streaming RPC that returns transaction IDs that have
@@ -237,11 +238,11 @@ func (s *lwdStreamer) GetTreeState(ctx context.Context, id *walletrpc.BlockID) (
 }
 
 func (s *lwdStreamer) GetLatestTreeState(ctx context.Context, in *walletrpc.Empty) (*walletrpc.TreeState, error) {
-	latestHeight := s.cache.GetLatestHeight()
-
-	if latestHeight == -1 {
-		return nil, errors.New("Cache is empty. Server is probably not yet ready")
+	blockChainInfo, err := common.GetBlockChainInfo()
+	if err != nil {
+		return nil, err
 	}
+	latestHeight := blockChainInfo.Blocks
 	return s.GetTreeState(ctx, &walletrpc.BlockID{Height: uint64(latestHeight)})
 }