Recover TendermintState when empty proposal timer is fired in a wrong time

The Tendermint module was changing its step to 'Propose' when the
"engine timeout empty proposal" timer is fired. If the timer is called
in the wrong time the step should not be changed. This commit makes
the step change when it is needed.

Author: majecty

core/src/consensus/tendermint/types.rs

@@ -76,6 +76,15 @@ impl TendermintState {
         }
     }
 
+    pub fn is_propose_wait_empty_block_timer(&self) -> bool {
+        match self {
+            TendermintState::ProposeWaitEmptyBlockTimer {
+                ..
+            } => true,
+            _ => false,
+        }
+    }
+
     pub fn is_commit(&self) -> bool {
         match self {
             TendermintState::Commit {

core/src/consensus/tendermint/worker.rs

@@ -1214,25 +1214,27 @@ impl Worker {
     fn on_timeout(&mut self, token: usize) {
         // Timeout from empty block generation
         if token == ENGINE_TIMEOUT_EMPTY_PROPOSAL {
-            let prev_step = mem::replace(&mut self.step, TendermintState::Propose);
-            match prev_step {
-                TendermintState::ProposeWaitEmptyBlockTimer {
-                    block,
-                } => {
-                    if self.height == block.header().number() {
-                        cdebug!(
-                            ENGINE,
-                            "Empty proposal timer is finished, go to the prevote step and broadcast the block"
-                        );
-                        self.submit_proposal_block(block.as_ref());
-                    } else {
-                        cwarn!(ENGINE, "Empty proposal timer was for previous height.");
-                    }
-                }
-                _ => {
-                    cwarn!(ENGINE, "Empty proposal timer was not cleared.");
+            let block = if self.step.is_propose_wait_empty_block_timer() {
+                let previous = mem::replace(&mut self.step, TendermintState::Propose);
+                match previous {
+                    TendermintState::ProposeWaitEmptyBlockTimer {
+                        block,
+                    } => block,
+                    _ => unreachable!(),
                 }
+            } else {
+                cwarn!(ENGINE, "Empty proposal timer was not cleared.");
+                return
+            };
+
+            if self.height == block.header().number() {
+                cdebug!(ENGINE, "Empty proposal timer is finished, go to the prevote step and broadcast the block");
+                self.submit_proposal_block(block.as_ref());
+            } else {
+                self.move_to_step(TendermintState::Prevote, false);
+                cwarn!(ENGINE, "Empty proposal timer was for previous height.");
             }
+
             return
         }