FAB-2203 handle chaincode launch serially

https://jira.hyperledger.org/browse/FAB-2203

Chaincode-peer communication was made asynch to handle concurrent
invokes. The state machine requires that launch (one time operation)
requires serial communication to get into "ready" state. While it is not
incorrect to have async communication for launch also, it makes it hard
to write test cases against (we have to wait for CC to get to ready state).

A better approach would be for the system to enforce that at the end of init
the system woukd be in ready state for inits/invokes. This is achieved by
sending ready state serially to the CC.

Change-Id: Ib5d3ec1b6188d5aa933dbcb43adaf9995f75de2d
Signed-off-by: Srinivasan Muralidharan <muralisr@us.ibm.com>

core/chaincode/handler.go

@@ -67,6 +67,11 @@ type transactionContext struct {
 type nextStateInfo struct {
 	msg      *pb.ChaincodeMessage
 	sendToCC bool
+
+	//the only time we need to send synchronously is
+	//when launching the chaincode to take it to ready
+	//state (look for the panic when sending serial)
+	sendSync bool
 }
 
 //chaincode registered name is of the form
@@ -261,7 +266,13 @@ func (handler *Handler) deregister() error {
 }
 
 func (handler *Handler) triggerNextState(msg *pb.ChaincodeMessage, send bool) {
-	handler.nextState <- &nextStateInfo{msg, send}
+	//this will send Async
+	handler.nextState <- &nextStateInfo{msg: msg, sendToCC: send, sendSync: false}
+}
+
+func (handler *Handler) triggerNextStateSync(msg *pb.ChaincodeMessage) {
+	//this will send sync
+	handler.nextState <- &nextStateInfo{msg: msg, sendToCC: true, sendSync: true}
 }
 
 func (handler *Handler) waitForKeepaliveTimer() <-chan time.Time {
@@ -361,8 +372,18 @@ func (handler *Handler) processStream() error {
 
 		if nsInfo != nil && nsInfo.sendToCC {
 			chaincodeLogger.Debugf("[%s]sending state message %s", shorttxid(in.Txid), in.Type.String())
-			//if error bail in select
-			handler.serialSendAsync(in, errc)
+			//ready messages are sent sync
+			if nsInfo.sendSync {
+				if in.Type.String() != pb.ChaincodeMessage_READY.String() {
+					panic(fmt.Sprintf("[%s]Sync send can only be for READY state %s\n", shorttxid(in.Txid), in.Type.String()))
+				}
+				if err = handler.serialSend(in); err != nil {
+					return fmt.Errorf("[%s]Error sending ready  message, ending stream: %s", shorttxid(in.Txid), err)
+				}
+			} else {
+				//if error bail in select
+				handler.serialSendAsync(in, errc)
+			}
 		}
 	}
 }
@@ -1264,7 +1285,10 @@ func (handler *Handler) ready(ctxt context.Context, chainID string, txid string,
 		return nil, err
 	}
 
-	handler.triggerNextState(ccMsg, true)
+	//send the ready synchronously as the
+	//ready message is during launch and needs
+	//to happen before any init/invokes can sneak in
+	handler.triggerNextStateSync(ccMsg)
 
 	return txctx.responseNotifier, nil
 }