fix and add comment

Change-Id: I838bd4ec4400f11bfaebd67abb9596e0995cf6e8

src/kudu/master/catalog_manager.cc

@@ -386,11 +386,14 @@ TAG_FLAG(enable_deleted_tables_and_tablets_cleanup, runtime);
 
 DEFINE_int32(deleted_table_and_tablet_reserved_secs, 60 * 60,
              "After this amount of time, a deleted table/tablet could be actually removed by "
-             "catalog manager if '--enable_deleted_tables_and_tablets_cleanup=true'. ");
+             "catalog manager if --enable_deleted_tables_and_tablets_cleanup=true. ");
 TAG_FLAG(deleted_table_and_tablet_reserved_secs, experimental);
 TAG_FLAG(deleted_table_and_tablet_reserved_secs, runtime);
 
-DEFINE_bool(enable_chucked_tablet_writes, true, "");
+DEFINE_bool(enable_chucked_tablet_writes, true,
+            "Whether to split tablet actions into chunks when persisting them in sys.catalog "
+            "table. If disabled, any update of the sys.catalog table would be rejected if exceeds "
+            "--rpc_max_message_size.");
 TAG_FLAG(enable_chucked_tablet_writes, experimental);
 TAG_FLAG(enable_chucked_tablet_writes, runtime);
 
@@ -5582,7 +5585,7 @@ Status CatalogManager::ProcessDeletedTablets(const vector<scoped_refptr<TabletIn
   vector<scoped_refptr<TabletInfo>> tablets_to_clean_up;
   const time_t now = time(nullptr);
   for (const auto& tablet : tablets) {
-    CHECK(tablet->metadata().state().is_deleted());
+    DCHECK(tablet->metadata().state().is_deleted());
     if (!tablet->metadata().state().pb.has_delete_timestamp()) {
       // Set delete timestamp for the tablet.
       tablet->mutable_metadata()->mutable_dirty()->pb.set_delete_timestamp(now);
@@ -5593,7 +5596,7 @@ Status CatalogManager::ProcessDeletedTablets(const vector<scoped_refptr<TabletIn
       actions.tablets_to_delete.emplace_back(tablet);
     }
   }
-  // Persist the changes to the syscatalog table.
+  // Persist the changes to the sys.catalog table.
   const auto write_mode = FLAGS_enable_chucked_tablet_writes ? SysCatalogTable::WriteMode::CHUNKED
                                                              : SysCatalogTable::WriteMode::ATOMIC;
   Status s = sys_catalog_->Write(std::move(actions), write_mode);
@@ -5606,10 +5609,8 @@ Status CatalogManager::ProcessDeletedTablets(const vector<scoped_refptr<TabletIn
   {
     std::lock_guard<LockType> l(lock_);
     for (const auto& t : tablets_to_clean_up) {
-      if (tablet_map_.erase(t->id()) != 1) {
-        return Status::Corruption(
-            Substitute("Failed to remove tablet $0 from 'tablet_map_'.", t->id()));
-      }
+      DCHECK(ContainsKey(tablet_map_, t->id()));
+      tablet_map_.erase(t->id());
       VLOG(1) << "Cleaned up deleted tablet: " << t->id();
     }
   }
@@ -5626,7 +5627,7 @@ Status CatalogManager::ProcessDeletedTables(const vector<scoped_refptr<TableInfo
   const time_t now = time(nullptr);
   bool needs_clean_up_table;
   for (const auto& table : tables) {
-    CHECK(table->metadata().state().is_deleted());
+    DCHECK(table->metadata().state().is_deleted());
     SysCatalogTable::Actions action;
     if (!table->metadata().state().pb.has_delete_timestamp()) {
       table->mutable_metadata()->mutable_dirty()->pb.set_delete_timestamp(now);
@@ -5647,11 +5648,10 @@ Status CatalogManager::ProcessDeletedTables(const vector<scoped_refptr<TableInfo
     if (!needs_clean_up_table) {
       continue;
     }
+
     std::lock_guard<LockType> l(lock_);
-    if (table_ids_map_.erase(table->id()) != 1) {
-      return Status::Corruption(
-          Substitute("Failed to remove table $0 from 'table_id_map_'.", table->ToString()));
-    }
+    DCHECK(ContainsKey(table_ids_map_, table->id()));
+    table_ids_map_.erase(table->id());
     VLOG(1) << "Cleaned up deleted table: " << table->ToString();
   }