feat: all distributed time together (#2423)

src/common/meta/src/distributed_time_constants.rs

@@ -0,0 +1,31 @@
+// Copyright 2023 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::time::Duration;
+
+/// Heartbeat interval time (is the basic unit of various time).
+pub const HEARTBEAT_INTERVAL_MILLIS: u64 = 3000;
+
+/// The frontend will also send heartbeats to Metasrv, sending an empty
+/// heartbeat every HEARTBEAT_INTERVAL_MILLIS * 6 seconds.
+pub const FRONTEND_HEARTBEAT_INTERVAL_MILLIS: u64 = HEARTBEAT_INTERVAL_MILLIS * 6;
+
+/// The lease seconds of a region. It's set by 3 heartbeat intervals
+/// (HEARTBEAT_INTERVAL_MILLIS × 3), plus some extra buffer (1 second).
+pub const REGION_LEASE_SECS: u64 =
+    Duration::from_millis(HEARTBEAT_INTERVAL_MILLIS * 3).as_secs() + 1;
+
+/// When creating table or region failover, a target node needs to be selected.
+/// If the node's lease has expired, the `Selector` will not select it.
+pub const DATANODE_LEASE_SECS: u64 = REGION_LEASE_SECS;

src/common/meta/src/lib.rs

@@ -19,6 +19,7 @@ pub mod cache_invalidator;
 pub mod datanode_manager;
 pub mod ddl;
 pub mod ddl_manager;
+pub mod distributed_time_constants;
 pub mod error;
 pub mod heartbeat;
 pub mod instruction;