chore: add heartbeat metrics (#5929)

src/common/meta/src/datanode.rs

@@ -142,6 +142,43 @@ impl Stat {
         self.wcus = self.region_stats.iter().map(|s| s.wcus).sum();
         self.region_num = self.region_stats.len() as u64;
     }
+
+    pub fn memory_size(&self) -> usize {
+        // timestamp_millis, rcus, wcus
+        std::mem::size_of::<i64>() * 3 +
+        // id, region_num, node_epoch
+        std::mem::size_of::<u64>() * 3 +
+        // addr
+        std::mem::size_of::<String>() + self.addr.capacity() +
+        // region_stats
+        self.region_stats.iter().map(|s| s.memory_size()).sum::<usize>()
+    }
+}
+
+impl RegionStat {
+    pub fn memory_size(&self) -> usize {
+        // role
+        std::mem::size_of::<RegionRole>() +
+        // id
+        std::mem::size_of::<RegionId>() +
+        // rcus, wcus, approximate_bytes, num_rows
+        std::mem::size_of::<i64>() * 4 +
+        // memtable_size, manifest_size, sst_size, index_size
+        std::mem::size_of::<u64>() * 4 +
+        // engine
+        std::mem::size_of::<String>() + self.engine.capacity() +
+        // region_manifest
+        self.region_manifest.memory_size()
+    }
+}
+
+impl RegionManifestInfo {
+    pub fn memory_size(&self) -> usize {
+        match self {
+            RegionManifestInfo::Mito { .. } => std::mem::size_of::<u64>() * 2,
+            RegionManifestInfo::Metric { .. } => std::mem::size_of::<u64>() * 4,
+        }
+    }
 }
 
 impl TryFrom<&HeartbeatRequest> for Stat {

src/meta-srv/src/handler/extract_stat_handler.rs

@@ -19,6 +19,7 @@ use common_telemetry::{info, warn};
 use crate::error::Result;
 use crate::handler::{HandleControl, HeartbeatAccumulator, HeartbeatHandler};
 use crate::metasrv::Context;
+use crate::metrics::{METRIC_META_HEARTBEAT_RATE, METRIC_META_HEARTBEAT_STAT_MEMORY_SIZE};
 
 pub struct ExtractStatHandler;
 
@@ -42,6 +43,8 @@ impl HeartbeatHandler for ExtractStatHandler {
 
         match Stat::try_from(req) {
             Ok(stat) => {
+                METRIC_META_HEARTBEAT_RATE.inc();
+                METRIC_META_HEARTBEAT_STAT_MEMORY_SIZE.observe(stat.memory_size() as f64);
                 let _ = acc.stat.insert(stat);
             }
             Err(Some(header)) => {

src/meta-srv/src/metrics.rs

@@ -60,10 +60,10 @@ lazy_static! {
     /// The migration fail counter.
     pub static ref METRIC_META_REGION_MIGRATION_FAIL: IntCounter =
         register_int_counter!("greptime_meta_region_migration_fail", "meta region migration fail").unwrap();
-    /// The add region follower execute histogram.
-    pub static ref METRIC_META_ADD_REGION_FOLLOWER_EXECUTE: HistogramVec =
-        register_histogram_vec!("greptime_meta_add_region_follower_execute", "meta add region follower execute", &["state"]).unwrap();
-    /// The remove region follower execute histogram.
-    pub static ref METRIC_META_REMOVE_REGION_FOLLOWER_EXECUTE: HistogramVec =
-        register_histogram_vec!("greptime_meta_remove_region_follower_execute", "meta remove region follower execute", &["state"]).unwrap();
+    // The heartbeat stat memory size histogram.
+    pub static ref METRIC_META_HEARTBEAT_STAT_MEMORY_SIZE: Histogram =
+        register_histogram!("greptime_meta_heartbeat_stat_memory_size", "meta heartbeat stat memory size").unwrap();
+    // The heartbeat rate counter.
+    pub static ref METRIC_META_HEARTBEAT_RATE: IntCounter =
+        register_int_counter!("greptime_meta_heartbeat_rate", "meta heartbeat arrival rate").unwrap();
 }