consensus/pbft: avoid to rollback to previous state

Author: tailingchen

consensus/pbft/core/commit.go

@@ -62,7 +62,9 @@ func (c *core) handleCommit(msg *message, src pbft.Validator) error {
 
 	c.acceptCommit(msg, src)
 
-	if int64(c.current.Commits.Size()) > 2*c.F && c.state != StateCommitted {
+	// if has proposal and receives enough commit messages,
+	// it can chnage to StateCommitted directly to speed up the consensus process
+	if int64(c.current.Commits.Size()) > 2*c.F && c.state.Cmp(StateCommitted) < 0 {
 		c.commit()
 	}
 

consensus/pbft/core/prepare.go

@@ -62,8 +62,9 @@ func (c *core) handlePrepare(msg *message, src pbft.Validator) error {
 
 	c.acceptPrepare(msg, src)
 
-	// If 2f+1
-	if int64(c.current.Prepares.Size()) > 2*c.F && c.state != StatePrepared {
+	// change to StatePrepared if receving enough prepare messages
+	// and the current state is at previous state
+	if int64(c.current.Prepares.Size()) > 2*c.F && c.state.Cmp(StatePrepared) < 0 {
 		c.setState(StatePrepared)
 		c.sendCommit()
 	}

consensus/pbft/core/types.go

@@ -60,6 +60,20 @@ func (s State) String() string {
 	}
 }
 
+// Cmp compares s and y and returns:
+//   -1 if s is the previous state of y
+//    0 if s and y are the same state
+//   +1 if s is the next state of y
+func (s State) Cmp(y State) int {
+	if uint64(s) < uint64(y) {
+		return -1
+	}
+	if uint64(s) > uint64(y) {
+		return 1
+	}
+	return 0
+}
+
 const (
 	msgPreprepare uint64 = iota
 	msgPrepare