Leader scheduler groundwork for Blocktree (#2599)

* Groundwork for entry tree, align constants with definitions in the book

* Fix edge case in test, node can keep generating ticks between handle_role_transition and exit() call

src/leader_scheduler.rs

@@ -18,11 +18,14 @@ use solana_sdk::vote_transaction::VoteTransaction;
 use std::io::Cursor;
 use std::sync::Arc;
 
-pub const TICKS_PER_BLOCK: u64 = 4;
-pub const DEFAULT_BOOTSTRAP_HEIGHT: u64 = TICKS_PER_BLOCK * 256;
-pub const DEFAULT_LEADER_ROTATION_INTERVAL: u64 = TICKS_PER_BLOCK * 32;
-pub const DEFAULT_SEED_ROTATION_INTERVAL: u64 = TICKS_PER_BLOCK * 256;
-pub const DEFAULT_ACTIVE_WINDOW_LENGTH: u64 = TICKS_PER_BLOCK * 256;
+// At 10 ticks/s, 8 ticks per slot implies that leader rotation and voting will happen
+// every 800 ms. A fast voting cadence ensures faster finality and convergence
+pub const DEFAULT_TICKS_PER_SLOT: u64 = 8;
+// Bootstrap height lasts for ~100 seconds
+pub const DEFAULT_BOOTSTRAP_HEIGHT: u64 = 1024;
+pub const DEFAULT_SLOTS_PER_EPOCH: u64 = 64;
+pub const DEFAULT_SEED_ROTATION_INTERVAL: u64 = DEFAULT_SLOTS_PER_EPOCH * DEFAULT_TICKS_PER_SLOT;
+pub const DEFAULT_ACTIVE_WINDOW_LENGTH: u64 = DEFAULT_SEED_ROTATION_INTERVAL;
 
 pub struct LeaderSchedulerConfig {
     // The interval at which to rotate the leader, should be much less than
@@ -62,7 +65,7 @@ impl Default for LeaderSchedulerConfig {
     fn default() -> Self {
         Self {
             bootstrap_height: DEFAULT_BOOTSTRAP_HEIGHT,
-            leader_rotation_interval: DEFAULT_LEADER_ROTATION_INTERVAL,
+            leader_rotation_interval: DEFAULT_TICKS_PER_SLOT,
             seed_rotation_interval: DEFAULT_SEED_ROTATION_INTERVAL,
             active_window_length: DEFAULT_ACTIVE_WINDOW_LENGTH,
         }
@@ -184,6 +187,15 @@ impl LeaderScheduler {
         }
     }
 
+    // Returns the last tick height for a given slot index
+    pub fn max_tick_height_for_slot(&self, slot_index: u64) -> u64 {
+        if self.use_only_bootstrap_leader {
+            std::u64::MAX
+        } else {
+            slot_index * self.leader_rotation_interval + self.bootstrap_height
+        }
+    }
+
     // Let Leader X be the leader at the input tick height. This function returns the
     // the PoH height at which Leader X's slot ends.
     pub fn max_height_for_leader(&self, height: u64) -> Option<u64> {
@@ -517,7 +529,7 @@ pub mod tests {
     use crate::genesis_block::GenesisBlock;
     use crate::leader_scheduler::{
         LeaderScheduler, LeaderSchedulerConfig, DEFAULT_BOOTSTRAP_HEIGHT,
-        DEFAULT_LEADER_ROTATION_INTERVAL, DEFAULT_SEED_ROTATION_INTERVAL,
+        DEFAULT_SEED_ROTATION_INTERVAL, DEFAULT_TICKS_PER_SLOT,
     };
     use crate::vote_signer_proxy::VoteSignerProxy;
     use hashbrown::HashSet;
@@ -964,8 +976,8 @@ pub mod tests {
         // only one validator should be selected
         num_validators = 10;
         bootstrap_height = 1;
-        leader_rotation_interval = 1;
-        seed_rotation_interval = 1;
+        leader_rotation_interval = 1 as usize;
+        seed_rotation_interval = 1 as usize;
         run_scheduler_test(
             num_validators,
             bootstrap_height,
@@ -1156,7 +1168,7 @@ pub mod tests {
 
         assert_eq!(
             leader_scheduler.leader_rotation_interval,
-            DEFAULT_LEADER_ROTATION_INTERVAL
+            DEFAULT_TICKS_PER_SLOT
         );
         assert_eq!(
             leader_scheduler.seed_rotation_interval,

src/replay_stage.rs

@@ -10,7 +10,7 @@ use crate::entry_stream::EntryStreamHandler;
 #[cfg(test)]
 use crate::entry_stream::MockEntryStream as EntryStream;
 use crate::fullnode::TvuRotationSender;
-use crate::leader_scheduler::TICKS_PER_BLOCK;
+use crate::leader_scheduler::DEFAULT_TICKS_PER_SLOT;
 use crate::packet::BlobError;
 use crate::result::{Error, Result};
 use crate::service::Service;
@@ -112,7 +112,8 @@ impl ReplayStage {
         let mut did_rotate = false;
 
         // Next vote tick is ceiling of (current tick/ticks per block)
-        let mut num_ticks_to_next_vote = TICKS_PER_BLOCK - (bank.tick_height() % TICKS_PER_BLOCK);
+        let mut num_ticks_to_next_vote =
+            DEFAULT_TICKS_PER_SLOT - (bank.tick_height() % DEFAULT_TICKS_PER_SLOT);
         let mut start_entry_index = 0;
         for (i, entry) in entries.iter().enumerate() {
             inc_new_counter_info!("replicate-stage_bank-tick", bank.tick_height() as usize);
@@ -168,7 +169,7 @@ impl ReplayStage {
                     break;
                 }
                 start_entry_index = i + 1;
-                num_ticks_to_next_vote = TICKS_PER_BLOCK;
+                num_ticks_to_next_vote = DEFAULT_TICKS_PER_SLOT;
             }
         }
 

tests/multinode.rs

@@ -1238,7 +1238,6 @@ fn test_leader_validator_basic() {
 
     let leader_entries = read_ledger(&leader_ledger_path);
 
-    assert_eq!(leader_entries.len(), validator_entries.len());
     assert!(leader_entries.len() as u64 >= bootstrap_height);
 
     for (v, l) in validator_entries.iter().zip(leader_entries) {