From 95ad0ef745a19da8d56a3e00fb8d621fbb17d371 Mon Sep 17 00:00:00 2001
From: SeongChan Lee <sclee@codechain.io>
Date: Thu, 16 May 2019 18:25:27 +0900
Subject: [PATCH] Add method to check the end of a term

---
 core/src/client/importer.rs | 21 +++++++++++++++++++++
 core/src/consensus/mod.rs   |  5 +++++
 2 files changed, 26 insertions(+)

diff --git a/core/src/client/importer.rs b/core/src/client/importer.rs
index e562022f24..e8a2f07c72 100644
--- a/core/src/client/importer.rs
+++ b/core/src/client/importer.rs
@@ -38,6 +38,7 @@ use crate::types::BlockId;
 use crate::verification::queue::{BlockQueue, HeaderQueue};
 use crate::verification::{self, PreverifiedBlock, Verifier};
 use crate::views::{BlockView, HeaderView};
+use blockchain::BlockChain;
 
 pub struct Importer {
     /// Lock used during block import
@@ -206,6 +207,8 @@ impl Importer {
         client.db().write_buffered(batch);
         chain.commit();
 
+        self.check_term_end(block.header(), &chain, client);
+
         if hash == chain.best_block_hash() {
             let mut state_db = client.state_db().write();
             let state = block.state();
@@ -215,6 +218,21 @@ impl Importer {
         route
     }
 
+    fn check_term_end(&self, header: &Header, chain: &BlockChain, client: &Client) {
+        let last_term_end = chain.last_term_end();
+        if let Some(term_id) = self.engine.is_term_end(header, last_term_end) {
+            cdebug!(CLIENT, "Term end at block {}", header.hash());
+
+            let mut batch = DBTransaction::new();
+            chain.update_last_term_end(&mut batch, term_id, header.number());
+
+            // always write the batch directly since term end are
+            // fetched from a DB iterator and DB iterators are only available on
+            // flushed data.
+            client.db().write(batch).expect("DB flush failed");
+        }
+    }
+
     fn check_and_close_block(&self, block: &PreverifiedBlock, client: &Client) -> Result<LockedBlock, ()> {
         let engine = &*self.engine;
         let header = &block.header;
@@ -404,6 +422,9 @@ impl Importer {
         client.db().write_buffered(batch);
         chain.commit();
 
+        // FIXME: Check if this line is still necessary.
+        // self.check_term_end(&header, &chain, client);
+
         route
     }
 }
diff --git a/core/src/consensus/mod.rs b/core/src/consensus/mod.rs
index 35137db88b..bb861b3f4b 100644
--- a/core/src/consensus/mod.rs
+++ b/core/src/consensus/mod.rs
@@ -55,6 +55,7 @@ use crate::error::Error;
 use crate::header::Header;
 use crate::transaction::{SignedTransaction, UnverifiedTransaction};
 use crate::views::HeaderView;
+use blockchain::TermEnd;
 use Client;
 
 pub enum Seal {
@@ -199,6 +200,10 @@ pub trait ConsensusEngine: Sync + Send {
         Ok(())
     }
 
+    fn is_term_end(&self, _chain_head: &M::Header, _last_term_end: Option<TermEnd>) -> Option<u64> {
+        None
+    }
+
     /// Populate a header's fields based on its parent's header.
     /// Usually implements the chain scoring rule based on weight.
     fn populate_from_parent(&self, _header: &mut Header, _parent: &Header) {}