[TD-10645][raft]<feature>add vote resp process

source/libs/sync/inc/raft_replication.h

@@ -20,11 +20,11 @@
 #include "syncInt.h"
 #include "sync_type.h"
 
-// syncRaftReplicate sends an append RPC with new entries to the given peer,
+// syncRaftMaybeSendAppend sends an append RPC with new entries to the given peer,
 // if necessary. Returns true if a message was sent. The sendIfEmpty
 // argument controls whether messages with no entries will be sent
 // ("empty" messages are useful to convey updated Commit indexes, but
 // are undesirable when we're sending multiple messages in a batch).
-bool syncRaftReplicate(SSyncRaft* pRaft, SSyncRaftProgress* progress, bool sendIfEmpty);
+bool syncRaftMaybeSendAppend(SSyncRaft* pRaft, SSyncRaftProgress* progress, bool sendIfEmpty);
 
 #endif  /* TD_SYNC_RAFT_REPLICATION_H */

source/libs/sync/inc/sync_raft_impl.h

@@ -28,6 +28,8 @@ void syncRaftBecomeLeader(SSyncRaft* pRaft);
 
 void syncRaftStartElection(SSyncRaft* pRaft, ESyncRaftElectionType cType);
 
+void syncRaftCampaign(SSyncRaft* pRaft, ESyncRaftElectionType cType);
+
 void syncRaftTriggerHeartbeat(SSyncRaft* pRaft);
 
 void syncRaftRandomizedElectionTimeout(SSyncRaft* pRaft);

source/libs/sync/src/raft.c

@@ -169,7 +169,7 @@ static int deserializeClusterStateFromBuffer(SSyncConfigState* cluster, const ch
 }
 
 static void visitProgressMaybeSendAppend(SSyncRaftProgress* progress, void* arg) {
-  syncRaftReplicate(arg, progress, false);
+  syncRaftMaybeSendAppend(arg, progress, false);
 }
 
 // switchToConfig reconfigures this node to use the provided configuration. It

source/libs/sync/src/raft_handle_vote_message.c

@@ -48,12 +48,14 @@ int syncRaftHandleVoteMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg) {
 }
 
 static bool canGrantVoteMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg) {
-  if (!(pRaft->voteFor == SYNC_NON_NODE_ID || pMsg->term > pRaft->term || pRaft->voteFor == pMsg->from)) {
-    return false;
-  }
-  if (!syncRaftLogIsUptodate(pRaft->log, pMsg->vote.lastIndex, pMsg->vote.lastTerm)) {
-    return false;
-  }
-
-  return true;
+  bool canVote = 
+                  // We can vote if this is a repeat of a vote we've already cast...
+                 pRaft->voteFor == pMsg->from ||
+                  // ...we haven't voted and we don't think there's a leader yet in this term...
+                 (pRaft->voteFor == SYNC_NON_NODE_ID && pRaft->leaderId == SYNC_NON_NODE_ID) ||
+                  // ...or this is a PreVote for a future term...
+                 (pMsg->vote.cType == SYNC_RAFT_CAMPAIGN_PRE_ELECTION && pMsg->term > pRaft->term);
+
+  // ...and we believe the candidate is up to date.
+  return canVote && syncRaftLogIsUptodate(pRaft->log, pMsg->vote.lastIndex, pMsg->vote.lastTerm);
 }
\ No newline at end of file

source/libs/sync/src/raft_handle_vote_resp_message.c

@@ -45,12 +45,14 @@ int syncRaftHandleVoteRespMessage(SSyncRaft* pRaft, const SSyncMessage* pMsg) {
 
   if (result == SYNC_RAFT_VOTE_WON) {
     if (pRaft->candidateState.inPreVote) {
-      syncRaftStartElection(pRaft, SYNC_RAFT_CAMPAIGN_ELECTION);
+      syncRaftCampaign(pRaft, SYNC_RAFT_CAMPAIGN_ELECTION);
     } else {
       syncRaftBecomeLeader(pRaft);
-
+      syncRaftBroadcastAppend(pRaft);
     }
   } else if (result == SYNC_RAFT_VOTE_LOST) {
+		// pb.MsgPreVoteResp contains future term of pre-candidate
+		// m.Term > r.Term; reuse r.Term    
     syncRaftBecomeFollower(pRaft, pRaft->term, SYNC_NON_NODE_ID);
   }
 

source/libs/sync/src/raft_replication.c

@@ -24,12 +24,12 @@ static bool sendAppendEntries(SSyncRaft* pRaft, SSyncRaftProgress* progress,
                               SyncIndex prevIndex, SyncTerm prevTerm,
                               SSyncRaftEntry *entries, int nEntry);
 
-// syncRaftReplicate sends an append RPC with new entries to the given peer,
+// maybeSendAppend sends an append RPC with new entries to the given peer,
 // if necessary. Returns true if a message was sent. The sendIfEmpty
 // argument controls whether messages with no entries will be sent
 // ("empty" messages are useful to convey updated Commit indexes, but
 // are undesirable when we're sending multiple messages in a batch).
-bool syncRaftReplicate(SSyncRaft* pRaft, SSyncRaftProgress* progress, bool sendIfEmpty) {
+bool syncRaftMaybeSendAppend(SSyncRaft* pRaft, SSyncRaftProgress* progress, bool sendIfEmpty) {
   assert(pRaft->state == TAOS_SYNC_STATE_LEADER);
   SyncNodeId nodeId = progress->id;
 

source/libs/sync/src/sync_raft_election.c

@@ -19,8 +19,6 @@
 #include "raft_message.h"
 #include "sync_raft_progress_tracker.h"
 
-static void campaign(SSyncRaft* pRaft, ESyncRaftElectionType cType);
-
 void syncRaftStartElection(SSyncRaft* pRaft, ESyncRaftElectionType cType) {
   if (pRaft->state == TAOS_SYNC_STATE_LEADER) {
     syncDebug("[%d:%d] ignoring RAFT_MSG_INTERNAL_ELECTION because already leader", pRaft->selfGroupId, pRaft->selfId);
@@ -28,7 +26,7 @@ void syncRaftStartElection(SSyncRaft* pRaft, ESyncRaftElectionType cType) {
   }
 
   if (!syncRaftIsPromotable(pRaft)) {
-    syncWarn("[%d:%d] is unpromotable and can not campaign", pRaft->selfGroupId, pRaft->selfId);
+    syncWarn("[%d:%d] is unpromotable and can not syncRaftCampaign", pRaft->selfGroupId, pRaft->selfId);
     return;
   }
 
@@ -41,17 +39,17 @@ void syncRaftStartElection(SSyncRaft* pRaft, ESyncRaftElectionType cType) {
 
   syncInfo("[%d:%d] is starting a new election at term %" PRId64 "", pRaft->selfGroupId, pRaft->selfId, pRaft->term);
 
-  campaign(pRaft, cType);
+  syncRaftCampaign(pRaft, cType);
 }
 
-// campaign transitions the raft instance to candidate state. This must only be
+// syncRaftCampaign transitions the raft instance to candidate state. This must only be
 // called after verifying that this is a legitimate transition.
-static void campaign(SSyncRaft* pRaft, ESyncRaftElectionType cType) {
+void syncRaftCampaign(SSyncRaft* pRaft, ESyncRaftElectionType cType) {
   bool preVote;
   SyncTerm term;
 
   if (syncRaftIsPromotable(pRaft)) {
-    syncDebug("[%d:%d] is unpromotable; campaign() should have been called", pRaft->selfGroupId, pRaft->selfId);
+    syncDebug("[%d:%d] is unpromotable; syncRaftCampaign() should have been called", pRaft->selfGroupId, pRaft->selfId);
     return;
   }
 

source/libs/sync/src/sync_raft_impl.c

@@ -25,6 +25,8 @@ static int stepFollower(SSyncRaft* pRaft, const SSyncMessage* pMsg);
 static int stepCandidate(SSyncRaft* pRaft, const SSyncMessage* pMsg);
 static int stepLeader(SSyncRaft* pRaft, const SSyncMessage* pMsg);
 
+static bool increaseUncommittedSize(SSyncRaft* pRaft, SSyncRaftEntry* entries, int n);
+
 static int triggerAll(SSyncRaft* pRaft);
 
 static void tickElection(SSyncRaft* pRaft);
@@ -82,13 +84,22 @@ void syncRaftBecomeLeader(SSyncRaft* pRaft) {
   resetRaft(pRaft, pRaft->term);
   pRaft->leaderId = pRaft->leaderId;
   pRaft->state  = TAOS_SYNC_STATE_LEADER;
-  // TODO: check if there is pending config log
-  int nPendingConf = syncRaftLogNumOfPendingConf(pRaft->log);
-  if (nPendingConf > 1) {
-    syncFatal("unexpected multiple uncommitted config entry");
-  }
 
-  syncInfo("[%d:%d] became leader at term %" PRId64 "", pRaft->selfGroupId, pRaft->selfId, pRaft->term);
+  SSyncRaftProgress* progress = syncRaftFindProgressByNodeId(&pRaft->tracker->progressMap, pRaft->selfId);
+  assert(progress != NULL);
+	// Followers enter replicate mode when they've been successfully probed
+	// (perhaps after having received a snapshot as a result). The leader is
+	// trivially in this state. Note that r.reset() has initialized this
+	// progress with the last index already.  
+  syncRaftProgressBecomeReplicate(progress);
+
+	// Conservatively set the pendingConfIndex to the last index in the
+	// log. There may or may not be a pending config change, but it's
+	// safe to delay any future proposals until we commit all our
+	// pending log entries, and scanning the entire tail of the log
+	// could be expensive.
+  SyncIndex lastIndex = syncRaftLogLastIndex(pRaft->log);
+  pRaft->pendingConfigIndex = lastIndex;
 
   // after become leader, send a no-op log
   SSyncRaftEntry* entry = (SSyncRaftEntry*)malloc(sizeof(SSyncRaftEntry));
@@ -103,6 +114,7 @@ void syncRaftBecomeLeader(SSyncRaft* pRaft) {
   };
   appendEntries(pRaft, entry, 1);
   //syncRaftTriggerHeartbeat(pRaft);
+  syncInfo("[%d:%d] became leader at term %" PRId64 "", pRaft->selfGroupId, pRaft->selfId, pRaft->term);
 }
 
 void syncRaftTriggerHeartbeat(SSyncRaft* pRaft) {
@@ -192,9 +204,11 @@ static void visitProgressSendAppend(SSyncRaftProgress* progress, void* arg) {
     return;
   }
 
-  syncRaftReplicate(arg, progress, true);
+  syncRaftMaybeSendAppend(arg, progress, true);
 }
 
+// bcastAppend sends RPC, with entries to all peers that are not up-to-date
+// according to the progress recorded in r.prs.
 void syncRaftBroadcastAppend(SSyncRaft* pRaft) {
   syncRaftProgressVisit(pRaft->tracker, visitProgressSendAppend, pRaft);
 }
@@ -267,6 +281,11 @@ static void tickHeartbeat(SSyncRaft* pRaft) {
 
 }
 
+// TODO
+static bool increaseUncommittedSize(SSyncRaft* pRaft, SSyncRaftEntry* entries, int n) {
+  return false;
+}
+
 static void appendEntries(SSyncRaft* pRaft, SSyncRaftEntry* entries, int n) {
   SyncIndex lastIndex = syncRaftLogLastIndex(pRaft->log);
   SyncTerm term = pRaft->term;
@@ -277,9 +296,16 @@ static void appendEntries(SSyncRaft* pRaft, SSyncRaftEntry* entries, int n) {
     entries[i].index = lastIndex + 1 + i;
   }
 
+  // Track the size of this uncommitted proposal.
+  if (!increaseUncommittedSize(pRaft, entries, n)) {
+    // Drop the proposal.
+    return;    
+  }
+
   syncRaftLogAppend(pRaft->log, entries, n);
 
   SSyncRaftProgress* progress = syncRaftFindProgressByNodeId(&pRaft->tracker->progressMap, pRaft->selfId);
+  assert(progress != NULL);
   syncRaftProgressMaybeUpdate(progress, lastIndex);
   // Regardless of syncRaftMaybeCommit's return, our caller will call bcastAppend.
   syncRaftMaybeCommit(pRaft);
@@ -306,7 +332,7 @@ static int triggerAll(SSyncRaft* pRaft) {
       continue;
     }
 
-    syncRaftReplicate(pRaft, pRaft->tracker->progressMap.progress[i], true);
+    syncRaftMaybeSendAppend(pRaft, pRaft->tracker->progressMap.progress[i], true);
   }
   #endif
   return 0;