[rebuild] add get_election_leader()

src/logservice/ob_log_handler.cpp

@@ -404,6 +404,12 @@ int ObLogHandler::get_global_learner_list(common::GlobalLearnerList &learner_lis
   return palf_handle_.get_global_learner_list(learner_list);
 }
 
+int ObLogHandler::get_election_leader(common::ObAddr &addr) const
+{
+  RLockGuard guard(lock_);
+  return palf_handle_.get_election_leader(addr);
+}
+
 int ObLogHandler::enable_sync()
 {
   RLockGuard guard(lock_);

src/logservice/ob_log_handler.h

@@ -96,6 +96,7 @@ public:
   virtual int get_end_scn(share::SCN &scn) const = 0;
   virtual int get_paxos_member_list(common::ObMemberList &member_list, int64_t &paxos_replica_num) const = 0;
   virtual int get_global_learner_list(common::GlobalLearnerList &learner_list) const = 0;
+  virtual int get_election_leader(common::ObAddr &addr) const = 0;
   virtual int change_replica_num(const common::ObMemberList &member_list,
                                  const int64_t curr_replica_num,
                                  const int64_t new_replica_num,
@@ -292,6 +293,13 @@ public:
   // @brief, get global learner list of this paxos group
   // @param[out] common::GlobalLearnerList&
   int get_global_learner_list(common::GlobalLearnerList &learner_list) const override final;
+  // @brief, get leader from election, used for non_palf_leader rebuilding
+  // @param[out] addr: address of leader
+  // retval:
+  //   OB_SUCCESS
+  //   OB_NOT_INIT
+  //   OB_LEADER_NOT_EXIST
+  int get_election_leader(common::ObAddr &addr) const override final;
   // PalfBaseInfo include the 'base_lsn' and the 'prev_log_info' of sliding window.
   // @param[in] const LSN&, base_lsn of ls.
   // @param[out] PalfBaseInfo&, palf_base_info

src/logservice/palf/palf_handle.cpp

@@ -288,6 +288,12 @@ int PalfHandle::get_paxos_member_list(common::ObMemberList &member_list, int64_t
   return palf_handle_impl_->get_paxos_member_list(member_list, paxos_replica_num);
 }
 
+int PalfHandle::get_election_leader(common::ObAddr &addr) const
+{
+  CHECK_VALID;
+  return palf_handle_impl_->get_election_leader(addr);
+}
+
 int PalfHandle::change_replica_num(const common::ObMemberList &member_list,
                                    const int64_t curr_replica_num,
                                    const int64_t new_replica_num,

src/logservice/palf/palf_handle.h

@@ -178,6 +178,7 @@ public:
 
   int get_global_learner_list(common::GlobalLearnerList &learner_list) const;
   int get_paxos_member_list(common::ObMemberList &member_list, int64_t &paxos_replica_num) const;
+  int get_election_leader(common::ObAddr &addr) const;
 
   // @brief: a special config change interface, change replica number of paxos group
   // @param[in] common::ObMemberList: current memberlist, for pre-check

src/logservice/palf/palf_handle_impl.cpp

@@ -489,6 +489,14 @@ int PalfHandleImpl::get_paxos_member_list(
   return ret;
 }
 
+int PalfHandleImpl::get_election_leader(ObAddr &addr) const
+{
+  int ret = OB_SUCCESS;
+  RLockGuard guard(lock_);
+  ret = get_election_leader_without_lock_(addr);
+  return ret;
+}
+
 int PalfHandleImpl::config_change_pre_check(const ObAddr &server,
                                             const LogGetMCStReq &req,
                                             LogGetMCStResp &resp)
@@ -3478,6 +3486,22 @@ int PalfHandleImpl::append_disk_log_to_sw_(const LSN &start_lsn)
   return ret;
 }
 
+int PalfHandleImpl::get_election_leader_without_lock_(ObAddr &addr) const
+{
+  int ret = OB_SUCCESS;
+  int64_t unused_leader_epoch = -1;
+  if (IS_NOT_INIT) {
+    ret = OB_NOT_INIT;
+    PALF_LOG(ERROR, "PalfHandleImpl has not inited", K(ret));
+  } else if (OB_FAIL(election_.get_current_leader_likely(addr, unused_leader_epoch))) {
+    PALF_LOG(WARN, "get_election_leader failed", K(ret), KPC(this));
+  } else if (OB_UNLIKELY(!addr.is_valid())) {
+    ret = OB_LEADER_NOT_EXIST;
+    PALF_LOG(WARN, "election has no leader", K(ret), KPC(this));
+  }
+  return ret;
+}
+
 int PalfHandleImpl::revoke_leader(const int64_t proposal_id)
 {
   int ret = OB_SUCCESS;

src/logservice/palf/palf_handle_impl.h

@@ -238,6 +238,7 @@ public:
 
   virtual int get_global_learner_list(common::GlobalLearnerList &learner_list) const = 0;
   virtual int get_paxos_member_list(common::ObMemberList &member_list, int64_t &paxos_replica_num) const = 0;
+  virtual int get_election_leader(common::ObAddr &addr) const = 0;
 
   // @brief: a special config change interface, change replica number of paxos group
   // @param[in] common::ObMemberList: current memberlist, for pre-check
@@ -634,6 +635,7 @@ public:
   int change_leader_to(const common::ObAddr &dest_addr) override final;
   int get_global_learner_list(common::GlobalLearnerList &learner_list) const override final;
   int get_paxos_member_list(common::ObMemberList &member_list, int64_t &paxos_replica_num) const override final;
+  int get_election_leader(common::ObAddr &addr) const;
   int change_replica_num(const common::ObMemberList &member_list,
                          const int64_t curr_replica_num,
                          const int64_t new_replica_num,
@@ -913,6 +915,7 @@ private:
   int check_need_advance_base_info_(const LSN &base_lsn,
                                     const LogInfo &base_prev_log_info,
                                     const bool is_rebuild);
+  int get_election_leader_without_lock_(ObAddr &addr) const;
   // ========================= flashback ==============================
   int can_do_flashback_(const int64_t mode_version,
                         const share::SCN &flashback_scn,

unittest/storage/mock_ob_log_handler.h

@@ -409,6 +409,11 @@ public:
   }
   int enable_vote() { return OB_SUCCESS; }
   int disable_vote() { return OB_SUCCESS; }
+  int get_election_leader(common::ObAddr &addr) const
+  {
+    UNUSED(addr);
+    return OB_SUCCESS;
+  }
   int register_rebuild_cb(palf::PalfRebuildCb *rebuild_cb)
   {
     UNUSED(rebuild_cb);