From c833b1c013950feec6e580d0864cd2961f1fdfba Mon Sep 17 00:00:00 2001
From: Steve Lau <stevelauc@outlook.com>
Date: Sun, 1 Sep 2024 21:53:27 +0800
Subject: [PATCH] Doc: update doc of heartbeat metric

---
 openraft/src/metrics/mod.rs          |  4 ++--
 openraft/src/metrics/raft_metrics.rs | 18 ++++++++++--------
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/openraft/src/metrics/mod.rs b/openraft/src/metrics/mod.rs
index 16ba028be..b0c191adf 100644
--- a/openraft/src/metrics/mod.rs
+++ b/openraft/src/metrics/mod.rs
@@ -53,6 +53,6 @@ use crate::type_config::alias::NodeIdOf;
 use crate::type_config::alias::SerdeInstantOf;
 
 pub(crate) type ReplicationMetrics<C> = BTreeMap<NodeIdOf<C>, Option<LogIdOf<C>>>;
-/// Heartbeat metrics, a mapping between a node's ID and milliseconds since the
-/// last acknowledged heartbeat or replication to this node.
+/// Heartbeat metrics, a mapping between a node's ID and the time of the last
+/// acknowledged heartbeat or replication to this node.
 pub(crate) type HeartbeatMetrics<C> = BTreeMap<NodeIdOf<C>, Option<SerdeInstantOf<C>>>;
diff --git a/openraft/src/metrics/raft_metrics.rs b/openraft/src/metrics/raft_metrics.rs
index 9a3e8638f..2dcca9d53 100644
--- a/openraft/src/metrics/raft_metrics.rs
+++ b/openraft/src/metrics/raft_metrics.rs
@@ -98,11 +98,12 @@ pub struct RaftMetrics<C: RaftTypeConfig> {
 
     /// Heartbeat metrics. It is Some() only when this node is leader.
     ///
-    /// This field records a mapping between a node's ID and milliseconds since
-    /// the last acknowledged heartbeat or replication to this node.
+    /// This field records a mapping between a node's ID and the time of the
+    /// last acknowledged heartbeat or replication to this node.
     ///
-    /// This duration can be used by applications to guess if a follwer/learner
-    /// node is offline, longer duration suggests higher possibility of that.
+    /// This duration since the recorded time can be used by applications to
+    /// guess if a follwer/learner node is offline, longer duration suggests
+    /// higher possibility of that.
     pub heartbeat: Option<HeartbeatMetrics<C>>,
 
     // ---
@@ -227,11 +228,12 @@ pub struct RaftDataMetrics<C: RaftTypeConfig> {
 
     /// Heartbeat metrics. It is Some() only when this node is leader.
     ///
-    /// This field records a mapping between a node's ID and milliseconds since
-    /// the last acknowledged heartbeat or replication to this node.
+    /// This field records a mapping between a node's ID and the time of the
+    /// last acknowledged heartbeat or replication to this node.
     ///
-    /// This duration can be used by applications to guess if a follwer/learner
-    /// node is offline, longer duration suggests higher possibility of that.
+    /// This duration since the recorded time can be used by applications to
+    /// guess if a follwer/learner node is offline, longer duration suggests
+    /// higher possibility of that.
     pub heartbeat: Option<HeartbeatMetrics<C>>,
 }