Support timing auto flush plan cache

src/share/parameter/ob_parameter_seed.ipp

@@ -1312,3 +1312,6 @@ ERRSIM_DEF_STR(errsim_migration_src_server_addr, OB_CLUSTER_PARAMETER, "",
 DEF_BOOL(enable_cgroup, OB_CLUSTER_PARAMETER, "True",
          "when set to false, cgroup will not init; when set to true but cgroup root dir is not ready, print ERROR",
          ObParameterAttr(Section::OBSERVER, Source::DEFAULT, EditLevel::STATIC_EFFECTIVE));
+DEF_TIME(_ob_plan_cache_auto_flush_interval, OB_CLUSTER_PARAMETER, "0s", "[0s,)",
+         "time interval for auto periodic flush plan cache. Range: [0s, +∞)",
+         ObParameterAttr(Section::OBSERVER, Source::DEFAULT, EditLevel::DYNAMIC_EFFECTIVE));

src/sql/plan_cache/ob_plan_cache_manager.cpp

@@ -277,17 +277,24 @@ int ObPlanCacheManager::revert_plan_cache(const uint64_t &tenant_id)
 
 void ObPlanCacheManager::ObPlanCacheEliminationTask::runTimerTask()
 {
+#define NEED_AUTO_FLUSH_PC(v) (0 == v ? false : true)
   int ret = OB_SUCCESS;
   if (OB_ISNULL(plan_cache_manager_)) {
     ret = OB_NOT_INIT;
     SQL_PC_LOG(WARN, "plan_cache_manager not inited", K(ret));
   } else {
+    ++run_task_counter_;
+    const int64_t auto_flush_pc_interval = (int64_t)(GCONF._ob_plan_cache_auto_flush_interval) / (1000 * 1000L); // second
     {
       // 在调用plan cache接口前引用plan资源前必须定义guard
       observer::ObReqTimeGuard req_timeinfo_guard;
 
       run_plan_cache_task();
       run_ps_cache_task();
+      if (NEED_AUTO_FLUSH_PC(auto_flush_pc_interval)
+        && 0 == run_task_counter_ % auto_flush_pc_interval) {
+        run_auto_flush_plan_cache_task();
+      }
       SQL_PC_LOG(INFO, "schedule next cache evict task",
                 "evict_interval", (int64_t)(GCONF.plan_cache_evict_interval));
     }
@@ -306,6 +313,15 @@ void ObPlanCacheManager::ObPlanCacheEliminationTask::runTimerTask()
   }
 }
 
+void ObPlanCacheManager::ObPlanCacheEliminationTask::run_auto_flush_plan_cache_task()
+{
+  if (OB_ISNULL(plan_cache_manager_)) {
+    // do nothing
+  } else {
+    IGNORE_RETURN plan_cache_manager_->flush_all_plan_cache();
+  }
+}
+
 void ObPlanCacheManager::ObPlanCacheEliminationTask::run_plan_cache_task()
 {
   int ret = OB_SUCCESS;

src/sql/plan_cache/ob_plan_cache_manager.h

@@ -47,6 +47,7 @@ public:
     void run_plan_cache_task();
     void run_ps_cache_task();
     void run_free_cache_obj_task();
+    void run_auto_flush_plan_cache_task();
   public:
     ObPlanCacheManager *plan_cache_manager_;
     int64_t run_task_counter_;

tools/deploy/mysql_test/test_suite/inner_table/r/mysql/all_virtual_sys_parameter_stat.result

@@ -271,6 +271,7 @@ _ob_enable_prepared_statement
 _ob_get_gts_ahead_interval
 _ob_max_thread_num
 _ob_obj_dep_maint_task_interval
+_ob_plan_cache_auto_flush_interval
 _ob_plan_cache_gc_strategy
 _ob_query_rate_limit
 _ob_ssl_invited_nodes