From bcc2ba64ff1ed49dc3d4ffa9909326ed05ce4e1c Mon Sep 17 00:00:00 2001
From: Alexey Ozeritskiy <aozeritsky@gmail.com>
Date: Fri, 24 Nov 2023 20:55:34 +0300
Subject: [PATCH] OnRequestVote implemented

---
 src/raft.cpp | 34 ++++++++++++++++++++++++++++++++++
 src/raft.h   |  6 +++---
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/src/raft.cpp b/src/raft.cpp
index d069580..ea20d6f 100644
--- a/src/raft.cpp
+++ b/src/raft.cpp
@@ -67,6 +67,40 @@ TRaft::TRaft(int node, const TNodeDict& nodes, const std::shared_ptr<ITimeSource
 { }
 
 std::unique_ptr<TResult> TRaft::OnRequestVote(TMessageHolder<TRequestVoteRequest> message) {
+    if (message->Term < State->CurrentTerm) {
+        auto reply = NewHoldedMessage<TRequestVoteResponse>(static_cast<uint32_t>(EMessageType::REQUEST_VOTE_RESPONSE), sizeof(TRequestVoteResponse));
+        reply->Src = Id;
+        reply->Dst = message->Src;
+        reply->Term = State->CurrentTerm;
+        reply->VoteGranted = false;
+        return std::make_unique<TResult>(TResult {
+            .Message = reply
+        });
+    } else if (message->Term == State->CurrentTerm) {
+        bool accept = false;
+        if (State->VotedFor == 0) {
+            accept = true;
+        } else if (State->VotedFor == message->CandidateId && message->LastLogTerm > State->LogTerm()) {
+            accept = true;
+        } else if (State->VotedFor == message->CandidateId && message->LastLogTerm == State->LogTerm() && message->LastLogIndex >= State->Log.size()) {
+            accept = true;
+        }
+
+        auto reply = NewHoldedMessage<TRequestVoteResponse>(static_cast<uint32_t>(EMessageType::REQUEST_VOTE_RESPONSE), sizeof(TRequestVoteResponse));
+        reply->Src = Id;
+        reply->Dst = message->Src;
+        reply->Term = message->Term;
+        reply->VoteGranted = accept;
+
+        return std::make_unique<TResult>(TResult {
+            .NextState = std::make_unique<TState>(TState{
+                .CurrentTerm = message->Term,
+                .VotedFor = message->CandidateId
+            }),
+            .Message = reply,
+        });
+    }
+
     return nullptr;
 }
 
diff --git a/src/raft.h b/src/raft.h
index fe16c2b..6893edb 100644
--- a/src/raft.h
+++ b/src/raft.h
@@ -33,8 +33,8 @@ class TNode: public INode {
 };
 
 struct TState {
-    int CurrentTerm = 1;
-    int VotedFor = 0;
+    uint64_t CurrentTerm = 1;
+    uint32_t VotedFor = 0;
     std::vector<TMessageHolder<TLogEntry>> Log;
 
     int LogTerm(int index = -1) const {
@@ -105,7 +105,7 @@ class TRaft {
     TMessageHolder<TRequestVoteRequest> CreateVote();
     std::vector<TMessageHolder<TAppendEntriesRequest>> CreateAppendEntries();
 
-    int Id;
+    uint32_t Id;
     TNodeDict Nodes;
     std::shared_ptr<ITimeSource> TimeSource;
     int MinVotes;