Support configuring election timeout range (#63)

tikv · May 20, 2018 · 36d208d · 36d208d
1 parent 444e99e
commit 36d208d
Show file tree

Hide file tree

Showing 2 changed files with 82 additions and 2 deletions.
diff --git a/src/raft.rs b/src/raft.rs
@@ -124,6  124,14 @@ pub struct Config {
     /// rejoins the cluster.
     pub pre_vote: bool,
 
     /// The range of election timeout. In some cases, we hope some nodes has less possibility
     /// to become leader. This configuration ensures that the randomized election_timeout
     /// will always be suit in [min_election_tick, max_election_tick).
     /// If it is 0, then election_tick will be chosen.
     pub min_election_tick: usize,
     /// If it is 0, then 2 * election_tick will be chosen.
     pub max_election_tick: usize,
 
     /// read_only_option specifies how the read only request is processed.
     pub read_only_option: ReadOnlyOption,
 
@@ -137,6  145,24 @@ pub struct Config {
 }
 
 impl Config {
     #[inline]
     pub fn min_election_tick(&self) -> usize {
         if self.min_election_tick == 0 {
             self.election_tick
         } else {
             self.min_election_tick
         }
     }
 
     #[inline]
     pub fn max_election_tick(&self) -> usize {
         if self.max_election_tick == 0 {
             2 * self.election_tick
         } else {
             self.max_election_tick
         }
     }
 
     pub fn validate(&self) -> Result<()> {
         if self.id == INVALID_ID {
             return Err(Error::ConfigInvalid("invalid node id".to_owned()));
@@ -154,6  180,22 @@ impl Config {
             ));
         }
 
         let min_timeout = self.min_election_tick();
         let max_timeout = self.max_election_tick();
         if min_timeout < self.election_tick {
             return Err(Error::ConfigInvalid(format!(
                 "min election tick {} must not be less than election_tick {}",
                 min_timeout, self.election_tick
             )));
         }
 
         if min_timeout >= max_timeout {
             return Err(Error::ConfigInvalid(format!(
                 "min election tick {} should be less than max election tick {}",
                 min_timeout, max_timeout
             )));
         }
 
         if self.max_inflight_msgs == 0 {
             return Err(Error::ConfigInvalid(
                 "max inflight messages must be greater than 0".to_owned(),
@@ -232,9  274,11 @@ pub struct Raft<T: Storage> {
     election_timeout: usize,
 
     // randomized_election_timeout is a random number between
-    // [election_timeout, 2 * election_timeout - 1]. It gets reset
     // [min_election_timeout, max_election_timeout - 1]. It gets reset
     // when raft changes its state to follower or candidate.
     randomized_election_timeout: usize,
     min_election_timeout: usize,
     max_election_timeout: usize,
 
     /// Will be called when step** is about to be called.
     /// return false will skip step**.
@@ -322,6  366,8 @@ impl<T: Storage> Raft<T> {
             vote: Default::default(),
             heartbeat_elapsed: Default::default(),
             randomized_election_timeout: 0,
             min_election_timeout: c.min_election_tick(),
             max_election_timeout: c.max_election_tick(),
             skip_bcast_commit: c.skip_bcast_commit,
             tag: c.tag.to_owned(),
         };
@@ -410,6  456,7 @@ impl<T: Storage> Raft<T> {
 
     // for testing leader lease
     pub fn set_randomized_election_timeout(&mut self, t: usize) {
         assert!(self.min_election_timeout <= t && t < self.max_election_timeout);
         self.randomized_election_timeout = t;
     }
 
@@ -1973,7  2020,7 @@ impl<T: Storage> Raft<T> {
     pub fn reset_randomized_election_timeout(&mut self) {
         let prev_timeout = self.randomized_election_timeout;
         let timeout =
-            self.election_timeout   rand::thread_rng().gen_range(0, self.election_timeout);
             rand::thread_rng().gen_range(self.min_election_timeout, self.max_election_timeout);
         debug!(
             "{} reset election timeout {} -> {} at {}",
             self.tag, prev_timeout, timeout, self.election_elapsed

diff --git a/tests/cases/test_raft.rs b/tests/cases/test_raft.rs
@@ -4085,3  4085,36 @@ fn test_learner_respond_vote() {
     do_campaign(&mut network);
     assert_eq!(network.peers[&1].state, StateRole::Leader);
 }
 
 #[test]
 fn test_election_tick_range() {
     let mut cfg = new_test_config(1, vec![1, 2, 3], 10, 1);
     let mut raft = Raft::new(&cfg, new_storage());
     for _ in 0..1000 {
         raft.reset_randomized_election_timeout();
         let randomized_timeout = raft.get_randomized_election_timeout();
         assert!(
             cfg.election_tick <= randomized_timeout && randomized_timeout < 2 * cfg.election_tick
         );
     }
 
     cfg.min_election_tick = cfg.election_tick;
     cfg.validate().unwrap();
 
     // Too small election tick.
     cfg.min_election_tick = cfg.election_tick - 1;
     cfg.validate().unwrap_err();
 
     // max_election_tick should be larger than min_election_tick
     cfg.min_election_tick = cfg.election_tick;
     cfg.max_election_tick = cfg.election_tick;
     cfg.validate().unwrap_err();
 
     cfg.max_election_tick = cfg.election_tick   1;
     raft = Raft::new(&cfg, new_storage());
     for _ in 0..100 {
         raft.reset_randomized_election_timeout();
         let randomized_timeout = raft.get_randomized_election_timeout();
         assert_eq!(randomized_timeout, cfg.election_tick);
     }
 }