Introduce on_open_block

`on_open_block` is called when the block is created, before
processing any transactions included in the block.

Author: remagpie

core/src/consensus/mod.rs

@@ -221,6 +221,11 @@ pub trait ConsensusEngine: Sync + Send {
     /// Stops any services that the may hold the Engine and makes it safe to drop.
     fn stop(&self) {}
 
+    /// Block transformation functions, before the transactions.
+    fn on_open_block(&self, _block: &mut ExecutedBlock) -> Result<(), Error> {
+        Ok(())
+    }
+
     /// Block transformation functions, after the transactions.
     fn on_close_block(
         &self,

core/src/consensus/tendermint/engine.rs

@@ -134,6 +134,15 @@ impl ConsensusEngine for Tendermint {
 
     fn stop(&self) {}
 
+    /// Block transformation functions, before the transactions.
+    fn on_open_block(&self, block: &mut ExecutedBlock) -> Result<(), Error> {
+        let metadata = block.state().metadata()?.expect("Metadata must exist");
+        if block.header().number() == metadata.last_term_finished_block_num() + 1 {
+            // FIXME: on_term_open
+        }
+        Ok(())
+    }
+
     fn on_close_block(
         &self,
         block: &mut ExecutedBlock,