More refactoring

README.md

@@ -5,3 +5,19 @@ This project aims to develop an implementation of the Raft consensus protocol th
 We plan to leverage the implementation to create a highly-efficient setup for operating a redundant set of Nimbus beacon nodes and/or validator clients that rely on BLS threshold signatures to achieve improved resilience and security. Further details can be found in our roadmap here:
 
 https://github.com/status-im/nimbus-eth2/issues/3416
+
+This project is heavily inspired by Raft implementation in ScyllaDB 
+
+https://github.com/scylladb/scylladb/tree/master/raft
+
+# Design goals
+
+The main goal is to separate implementation of the raft state machin from the other implementation details like (storage, rpc etc)
+In order to achive this we want to keep the State machine absolutly deterministic every interaction the the world like 
+networking, logging, acquiring current time, random number generation, disc operation etc must happened trough the state machine interface.
+It will ensure better testability and integrability.
+
+
+# Run test
+
+`./run_all_tests.sh`

raft/consensus_state_machine.nim

@@ -10,6 +10,7 @@
 import types
 import log
 import tracker
+import state
 
 import std/[times]
 import std/sequtils
@@ -49,7 +50,6 @@ type
       of Accepted: accepted: RaftRpcAppendReplayAccepted
       of Rejected: rejected: RaftRpcAppendReplayRejected 
 
-
   RaftRpcVoteRequest* = object
     currentTerm*: RaftNodeTerm
     lastLogIndex*: RaftLogIndex
@@ -60,15 +60,6 @@ type
     currentTerm*: RaftNodeTerm
     voteGranted*: bool
 
-  LeaderState* = object
-    tracker: RaftTracker
-
-  CandidateState* = object
-    votes: RaftVotes
-
-  FollowerState* = object
-    leader: RaftNodeId
-
   RaftRpcMessage* = object
     currentTerm*: RaftNodeTerm
     sender*: RaftNodeId
@@ -89,12 +80,6 @@ type
     votedFor*: Option[RaftNodeId]
     stateChange*: bool
 
-  RaftStateMachineState* = object
-    case state: RaftNodeState
-    of rnsFollower: follower : FollowerState
-    of rnsCandidate: candidate: CandidateState
-    of rnsLeader: leader: LeaderState
-
   RaftStateMachine* = object
     myId*: RaftNodeId
     term*: RaftNodeTerm
@@ -117,25 +102,6 @@ type
 
     state*: RaftStateMachineState
 
-
-func isLeader*(s: RaftStateMachineState): bool =
-  return s.state == RaftNodeState.rnsLeader
-
-func isFollower*(s: RaftStateMachineState): bool =
-  return s.state == RaftNodeState.rnsFollower
-
-func isCandidate*(s: RaftStateMachineState): bool =
-  return s.state == RaftNodeState.rnsCandidate
-
-func leader*(s: var RaftStateMachineState): var LeaderState =
-  return s.leader
-
-func follower*(s: var RaftStateMachineState): var FollowerState =
-  return s.follower
-
-func candidate*(s: var RaftStateMachineState): var CandidateState =
-  return s.candidate
-
 func leader*(sm: var RaftStateMachine): var LeaderState =
   return sm.state.leader
 
@@ -146,7 +112,7 @@ func candidate*(sm: var RaftStateMachine): var CandidateState =
   return sm.state.candidate
 
 func debug*(sm: var RaftStateMachine, log: string) = 
-  sm.output.debugLogs.add("[" & $(sm.timeNow - sm.startTime).inMilliseconds & "ms] [" & (($sm.myId)[0..7]) & "...] [" & $sm.state.state & "]: " & log)
+  sm.output.debugLogs.add("[" & $(sm.timeNow - sm.startTime).inMilliseconds & "ms] [" & (($sm.myId)[0..7]) & "...] [" & $sm.state & "]: " & log)
 
 proc resetElectionTimeout*(sm: var RaftStateMachine) =
   # TODO actually pick random time
@@ -157,7 +123,7 @@ proc initRaftStateMachine*(id: RaftnodeId, currentTerm: RaftNodeTerm, log: RaftL
   sm.term = currentTerm
   sm.log = log
   sm.commitIndex = commitIndex
-  sm.state = RaftStateMachineState(state: RaftnodeState.rnsFollower)
+  sm.state = initFollower(RaftNodeId())
   sm.config = config
   sm.lastElectionTime = now
   sm.timeNow = now
@@ -168,7 +134,6 @@ proc initRaftStateMachine*(id: RaftnodeId, currentTerm: RaftNodeTerm, log: RaftL
   sm.resetElectionTimeout()
   return sm
 
-
 func findFollowerProggressById(sm: var RaftStateMachine, id: RaftNodeId): Option[RaftFollowerProgressTracker] =
   return sm.leader.tracker.find(id)
 
@@ -247,7 +212,7 @@ func becomeFollower*(sm: var RaftStateMachine, leaderId: RaftNodeId) =
   if sm.myId == leaderId:
     sm.debug "Can't be follower of itself"
   sm.output.stateChange = not sm.state.isFollower
-  sm.state = RaftStateMachineState(state: RaftNodeState.rnsFollower, follower: FollowerState(leader: leaderId))
+  sm.state = initFollower(leaderId)
   if leaderId != RaftnodeId():
     sm.pingLeader = false
     # TODO: Update last election time
@@ -258,9 +223,8 @@ func becomeLeader*(sm: var RaftStateMachine) =
     return
 
   sm.output.stateChange = true
-  sm.state = RaftStateMachineState(state: RaftnodeState.rnsLeader, leader: LeaderState())
   sm.addEntry(Empty())
-  sm.leader.tracker = initTracker(sm.config, sm.log.lastIndex, sm.timeNow)
+  sm.state = initLeader(sm.config, sm.log.lastIndex, sm.timeNow)
   sm.pingLeader = false
   #TODO: Update last election time  
   return
@@ -270,7 +234,7 @@ func becomeCandidate*(sm: var RaftStateMachine) =
   if not sm.state.isCandidate:
     sm.output.stateChange = true
 
-  sm.state = RaftStateMachineState(state: RaftnodeState.rnsCandidate, candidate: CandidateState(votes: initVotes(sm.config)))
+  sm.state = initCandidate(sm.config)
   sm.lastElectionTime = sm.timeNow
   # TODO: Add configuration change logic
 
@@ -327,7 +291,6 @@ func tick*(sm: var RaftStateMachine, now: times.DateTime) =
       sm.debug "Become candidate"
       sm.becomeCandidate()
     
-
 func poll*(sm: var RaftStateMachine):  RaftStateMachineOutput =
   # Should initiate replication if we have new entries
   if sm.state.isLeader:
@@ -338,7 +301,6 @@ func poll*(sm: var RaftStateMachine):  RaftStateMachineOutput =
 
   let output = sm.output
   sm.output = RaftStateMachineOutput()
-
   return output
 
 func commit*(sm: var RaftStateMachine) =
@@ -392,7 +354,6 @@ func advanceCommitIdx(sm: var RaftStateMachine, leaderIdx: RaftLogIndex) =
     sm.commitIndex = newIdx
     # TODO: signal the output for the update
 
-
 func appendEntry*(sm: var RaftStateMachine, fromId: RaftNodeId, request: RaftRpcAppendRequest) =
   if not sm.state.isFollower:
     sm.debug "You can't append append request to the non follower"
@@ -419,7 +380,6 @@ func requestVote*(sm: var RaftStateMachine, fromId: RaftNodeId, request: RaftRpc
     let responce: RaftRpcVoteReplay = RaftRpcVoteReplay(currentTerm: sm.term, voteGranted: false)
     sm.sendTo(fromId, responce)
 
-
 func requestVoteReply*(sm: var RaftStateMachine, fromId: RaftNodeId, request: RaftRpcVoteReplay) = 
   if not sm.state.isCandidate:
     sm.debug "Non candidate can't handle votes"

raft/state.nim

@@ -0,0 +1,57 @@
+
+import types
+import tracker
+
+import std/[times]
+type
+  RaftNodeState = enum
+    rnsFollower = 0,                        # Follower state
+    rnsCandidate = 1                        # Candidate state
+    rnsLeader = 2                           # Leader state
+
+  RaftStateMachineState* = object
+    case state: RaftNodeState
+    of rnsFollower: follower: FollowerState
+    of rnsCandidate: candidate: CandidateState
+    of rnsLeader: leader: LeaderState
+
+  LeaderState* = object
+    tracker*: RaftTracker
+
+  CandidateState* = object
+    votes*: RaftVotes
+
+  FollowerState* = object
+    leader*: RaftNodeId
+
+func `$`*(s: RaftStateMachineState): string =
+  return $s.state
+
+func initLeader*(cfg: RaftConfig, index: RaftLogIndex, now: times.DateTime): RaftStateMachineState =
+  var state = RaftStateMachineState(state: RaftnodeState.rnsLeader, leader: LeaderState())
+  state.leader.tracker = initTracker(cfg, index, now)
+  return state
+
+func initFollower*(leaderId: RaftNodeId): RaftStateMachineState =
+  return RaftStateMachineState(state: RaftNodeState.rnsFollower, follower: FollowerState(leader: leaderId))
+
+func initCandidate*(cfg: RaftConfig): RaftStateMachineState =
+  return RaftStateMachineState(state: RaftnodeState.rnsCandidate, candidate: CandidateState(votes: initVotes(cfg)))
+
+func isLeader*(s: RaftStateMachineState): bool =
+  return s.state == RaftNodeState.rnsLeader
+
+func isFollower*(s: RaftStateMachineState): bool =
+  return s.state == RaftNodeState.rnsFollower
+
+func isCandidate*(s: RaftStateMachineState): bool =
+  return s.state == RaftNodeState.rnsCandidate
+
+func leader*(s: var RaftStateMachineState): var LeaderState =
+  return s.leader
+
+func follower*(s: var RaftStateMachineState): var FollowerState =
+  return s.follower
+
+func candidate*(s: var RaftStateMachineState): var CandidateState =
+  return s.candidate

raft/tracker.nim

@@ -76,7 +76,6 @@ func tallyVote*(rv: var RaftVotes): RaftElectionResult =
   # TODO: Add support for configuration
   return rv.current.tallyVote()
 
-
 func find*(ls: RaftTracker, id: RaftnodeId): Option[RaftFollowerProgressTracker] =
   for follower in ls.progress:
     if follower.id == id:

raft/types.nim

@@ -26,11 +26,6 @@ const
   DefaultUUID* = initUUID(0, 0)             # 00000000-0000-0000-0000-000000000000
 
 type
-  RaftNodeState* = enum
-    rnsFollower = 0,                        # Follower state
-    rnsCandidate = 1                        # Candidate state
-    rnsLeader = 2                           # Leader state
-
   RaftNodeId* = UUID                        # uuid4 uniquely identifying every Raft Node
   RaftNodeTerm* = int                       # Raft Node Term Type
   RaftLogIndex* = int                       # Raft Node Log Index Type

tests/test_consensus_state_machine.nim

@@ -12,6 +12,7 @@ import ../raft/types
 import ../raft/consensus_state_machine
 import ../raft/log
 import ../raft/tracker
+import ../raft/state
 import std/[times, sequtils]
 import uuids
 import tables
@@ -57,17 +58,14 @@ proc advance(tc: var TestCluster, now: times.DateTime) =
         #echo "rpc:" & $msg
         tc.nodes[msg.receiver].advance(msg, now)
     
-
 func getLeader(tc: TestCluster): Option[RaftStateMachine] = 
   for id, node in tc.nodes:
     if node.state.isLeader:
       return some(node)
   return none(RaftStateMachine)
   
-
 proc consensusstatemachineMain*() =
 
-
   suite "Basic state machine tests":
     test "create state machine":
       var cluster = createCluster(test_ids_1, times.now())
@@ -367,6 +365,5 @@ proc consensusstatemachineMain*() =
           else:
             check false
 
-
 if isMainModule:
   consensusstatemachineMain()