optimize get_clog_parent interface.

src/clog/ob_log_cascading_mgr.cpp

@@ -229,7 +229,10 @@ int ObLogCascadingMgr::set_parent_(const common::ObAddr& new_parent_addr, const
   } else {
     state_mgr_->reset_need_rebuild();
     state_mgr_->reset_fetch_state();
+    if (parent_.is_valid()) {
+      // update prev_parent by valid old parent
       prev_parent_ = parent_;
+    }
     parent_ = new_parent;
     if (partition_reach_time_interval(60 * 1000 * 1000, update_parent_warn_time_)) {
       CLOG_LOG(INFO,

src/clog/ob_log_cascading_mgr.h

@@ -98,6 +98,10 @@ public:
   {
     return parent_;
   }
+  share::ObCascadMember get_prev_parent() const
+  {
+    return prev_parent_;
+  }
   common::ObAddr get_parent_addr() const
   {
     return parent_.get_server();

src/clog/ob_partition_log_service.cpp

@@ -1319,7 +1319,7 @@ int ObPartitionLogService::get_leader(common::ObAddr& leader) const
   return ret;
 }
 
-int ObPartitionLogService::get_clog_parent(common::ObAddr& parent, int64_t& cluster_id) const
+int ObPartitionLogService::get_clog_parent_for_migration(common::ObAddr &parent, int64_t &cluster_id) const
 {
   int ret = OB_SUCCESS;
   RLockGuard guard(lock_);
@@ -1330,22 +1330,34 @@ int ObPartitionLogService::get_clog_parent(common::ObAddr& parent, int64_t& clus
     parent = restore_mgr_.get_restore_leader();
     cluster_id = state_mgr_.get_self_cluster_id();
   } else {
+    const bool is_paxos_replica = ObReplicaTypeCheck::is_paxos_replica(mm_.get_replica_type());
     const share::ObCascadMember parent_member = cascading_mgr_.get_parent();
+    const share::ObCascadMember prev_parent_member = cascading_mgr_.get_prev_parent();
+    share::ObCascadMember cascad_leader;
+    (void)state_mgr_.get_cascad_leader(cascad_leader);
     if (parent_member.is_valid()) {
       parent = parent_member.get_server();
       cluster_id = parent_member.get_cluster_id();
-    } else {
+    } else if (!is_paxos_replica && prev_parent_member.is_valid()) {
+      // prev_parent is preferred choice for non-paxos replica
+      parent = prev_parent_member.get_server();
+      cluster_id = prev_parent_member.get_cluster_id();
+    } else if (cascad_leader.is_valid()) {
       // returns corresponding leader when parent is invalid
-      share::ObCascadMember cascad_leader;
-      (void)state_mgr_.get_cascad_leader(cascad_leader);
       parent = cascad_leader.get_server();
       cluster_id = cascad_leader.get_cluster_id();
+    } else if (prev_parent_member.is_valid()) {
+      // at last return prev_parent
+      parent = prev_parent_member.get_server();
+      cluster_id = prev_parent_member.get_cluster_id();
+    } else {
+      // it does not have valid parent
     }
   }
   if (!parent.is_valid()) {
     ret = OB_NEED_RETRY;
   }
-  CLOG_LOG(INFO, "get clog parent", K(ret), K_(partition_key), K(parent));
+  CLOG_LOG(INFO, "get clog parent", K(ret), K_(partition_key), K(parent), K(cluster_id));
   return ret;
 }
 

src/clog/ob_partition_log_service.h

@@ -249,7 +249,7 @@ public:
   virtual common::ObPartitionKey get_partition_key() const = 0;
   virtual int get_saved_base_storage_info(common::ObBaseStorageInfo& base_storage_info) const = 0;
   virtual int get_leader(common::ObAddr& leader) const = 0;
-  virtual int get_clog_parent(common::ObAddr& parent, int64_t& cluster_id) const = 0;
+  virtual int get_clog_parent_for_migration(common::ObAddr &parent, int64_t &cluster_id) const = 0;
   virtual int change_leader(const common::ObAddr& leader, common::ObTsWindows& changing_leader_windows) = 0;
   virtual int change_restore_leader(const common::ObAddr& leader) = 0;
   virtual int check_and_set_restore_progress() = 0;
@@ -523,7 +523,7 @@ public:
   virtual common::ObPartitionKey get_partition_key() const override;
   virtual int get_saved_base_storage_info(common::ObBaseStorageInfo& base_storage_info) const override;
   virtual int get_leader(common::ObAddr& addr) const override;
-  virtual int get_clog_parent(common::ObAddr& parent, int64_t& cluster_id) const override;
+  virtual int get_clog_parent_for_migration(common::ObAddr &parent, int64_t &cluster_id) const;
   virtual int change_leader(const common::ObAddr& leader, common::ObTsWindows& changing_leader_windows) override;
   virtual int change_restore_leader(const common::ObAddr& leader) override;
   virtual int check_and_set_restore_progress() override;

src/storage/ob_partition_migrator.cpp

@@ -13261,7 +13261,7 @@ int ObMigrateGetLeaderUtil::get_clog_parent(clog::ObIPartitionLogService &log_se
   ObAddr parent_src;
   int64_t cluster_id = -1;
 
-  if (OB_FAIL(log_service.get_clog_parent(parent_src, cluster_id))) {
+  if (OB_FAIL(log_service.get_clog_parent_for_migration(parent_src, cluster_id))) {
     STORAGE_LOG(WARN, "get parent addr failed", K(ret));
   } else {
     parent_info.src_addr_ = parent_src;

src/storage/ob_partition_service.cpp

@@ -13386,7 +13386,7 @@ int ObPartitionService::get_primary_cluster_migrate_src(const common::ObPartitio
       ret = OB_ERR_UNEXPECTED;
       LOG_WARN("log service should not be NULL", K(ret), K(pkey));
     } else if (FALSE_IT(is_restore = partition->get_pg_storage().is_restore())) {
-    } else if (OB_FAIL(log_service->get_clog_parent(src_info.src_addr_, src_info.cluster_id_))) {
+    } else if (OB_FAIL(log_service->get_clog_parent_for_migration(src_info.src_addr_, src_info.cluster_id_))) {
       if (OB_NEED_RETRY == ret) {
         ret = OB_SUCCESS;
       } else {
@@ -13463,7 +13463,7 @@ int ObPartitionService::get_standby_cluster_migrate_src(const common::ObPartitio
       ret = OB_ERR_UNEXPECTED;
       LOG_WARN("log service should not be NULL", K(ret), K(pkey));
     } else if (ObRole::STANDBY_LEADER == role) {
-      if (OB_FAIL(log_service->get_clog_parent(src_info.src_addr_, src_info.cluster_id_))) {
+      if (OB_FAIL(log_service->get_clog_parent_for_migration(src_info.src_addr_, src_info.cluster_id_))) {
         if (OB_NEED_RETRY == ret) {
           ret = OB_SUCCESS;
         } else {
@@ -13472,7 +13472,7 @@ int ObPartitionService::get_standby_cluster_migrate_src(const common::ObPartitio
       } else if (OB_FAIL(add_migrate_src(src_info, src_set, src_array))) {
         LOG_WARN("failed to add migrate src", K(ret), K(role), K(src_info), K(pkey));
       } else {
-        LOG_INFO("get_clog_parent", K(src_info));
+        LOG_INFO("get_clog_parent_for_migration", K(src_info));
         src_info.reset();
       }
     }

src/storage/ob_rebuild_scheduler.cpp

@@ -245,7 +245,7 @@ int ObRebuildReplicaTaskProducer::build_local_replica_info()
         // skip
       } else if (OB_FAIL(partition->get_pg_storage().get_pg_meta(pg_meta))) {
         STORAGE_LOG(WARN, "failed to get pg meta", K(ret), K(partition->get_partition_key()));
-      } else if (OB_FAIL(partition->get_log_service()->get_clog_parent(parent_addr, parent_cluster_id))) {
+      } else if (OB_FAIL(partition->get_log_service()->get_clog_parent_for_migration(parent_addr, parent_cluster_id))) {
         STORAGE_LOG(WARN, "get parent addr failed", K(ret));
       } else {
         // now only consider memstore pecent 0 is D replica, and read-only replica in ofs mode.

unittest/clog/mock_ob_partition_log_service.h

@@ -528,7 +528,7 @@ public:
     UNUSED(leader);
     return common::OB_SUCCESS;
   }
-  virtual int get_clog_parent(common::ObAddr& parent, int64_t& cluster_id) const
+  virtual int get_clog_parent_for_migration(common::ObAddr &parent, int64_t &cluster_id) const
   {
     UNUSED(parent);
     UNUSED(cluster_id);