refactor(metrics): use counter rather than gauge for inc-only metrics

rust/meta/src/hummock/hummock_manager.rs

@@ -1,7 +1,7 @@
 use std::sync::Arc;
 
 use itertools::{enumerate, Itertools};
-use prometheus::core::{AtomicF64, AtomicI64, GenericGauge};
+use prometheus::core::{AtomicF64, AtomicU64, GenericCounter};
 use prost::Message;
 use risingwave_common::error::{ErrorCode, Result};
 use risingwave_pb::hummock::hummock_version::HummockVersionRefId;
@@ -239,20 +239,22 @@ where
         }
     }
 
-    fn single_level_stat_bytes<T: FnMut(String) -> prometheus::Result<GenericGauge<AtomicF64>>>(
+    fn single_level_stat_bytes<
+        T: FnMut(String) -> prometheus::Result<GenericCounter<AtomicF64>>,
+    >(
         mut metric_vec: T,
         level_stat: &TableSetStatistics,
     ) {
         let level_label = String::from("L") + &level_stat.level_idx.to_string();
-        metric_vec(level_label).unwrap().add(level_stat.size_gb);
+        metric_vec(level_label).unwrap().inc_by(level_stat.size_gb);
     }
 
-    fn single_level_stat_sstn<T: FnMut(String) -> prometheus::Result<GenericGauge<AtomicI64>>>(
+    fn single_level_stat_sstn<T: FnMut(String) -> prometheus::Result<GenericCounter<AtomicU64>>>(
         mut metric_vec: T,
         level_stat: &TableSetStatistics,
     ) {
         let level_label = String::from("L") + &level_stat.level_idx.to_string();
-        metric_vec(level_label).unwrap().add(level_stat.cnt as i64);
+        metric_vec(level_label).unwrap().inc_by(level_stat.cnt);
     }
 
     fn trigger_rw_stat(&self, compact_metrics: &CompactMetrics) {

rust/meta/src/rpc/metrics.rs

@@ -4,9 +4,9 @@ use std::sync::Arc;
 use hyper::{Body, Request, Response};
 use itertools::Itertools;
 use prometheus::{
-    histogram_opts, register_gauge_vec_with_registry, register_histogram_vec_with_registry,
+    histogram_opts, register_counter_vec_with_registry, register_histogram_vec_with_registry,
     register_histogram_with_registry, register_int_counter_vec_with_registry,
-    register_int_gauge_vec_with_registry, Encoder, GaugeVec, Histogram, HistogramVec,
+    register_int_gauge_vec_with_registry, CounterVec, Encoder, Histogram, HistogramVec,
     IntCounterVec, IntGaugeVec, Registry, TextEncoder, DEFAULT_BUCKETS,
 };
 use tower::make::Shared;
@@ -30,17 +30,17 @@ pub struct MetaMetrics {
     /// num of SSTs to be merged to next level in each level
     pub level_compact_cnt: IntGaugeVec,
     /// GBs read from current level during history compactions to next level
-    pub level_compact_read_curr: GaugeVec,
+    pub level_compact_read_curr: CounterVec,
     /// GBs read from next level during history compactions to next level
-    pub level_compact_read_next: GaugeVec,
+    pub level_compact_read_next: CounterVec,
     /// GBs written into next level during history compactions to next level
-    pub level_compact_write: GaugeVec,
+    pub level_compact_write: CounterVec,
     /// num of SSTs read from current level during history compactions to next level
-    pub level_compact_read_sstn_curr: IntGaugeVec,
+    pub level_compact_read_sstn_curr: IntCounterVec,
     /// num of SSTs read from next level during history compactions to next level
-    pub level_compact_read_sstn_next: IntGaugeVec,
+    pub level_compact_read_sstn_next: IntCounterVec,
     /// num of SSTs written into next level during history compactions to next level
-    pub level_compact_write_sstn: IntGaugeVec,
+    pub level_compact_write_sstn: IntCounterVec,
     /// num of compactions from each level to next level
     pub level_compact_frequence: IntCounterVec,
 }
@@ -81,47 +81,47 @@ impl MetaMetrics {
         )
         .unwrap();
 
-        let level_compact_read_curr = register_gauge_vec_with_registry!(
+        let level_compact_read_curr = register_counter_vec_with_registry!(
             "storage_level_compact_read_curr",
             "GBs read from current level during history compactions to next level",
             &["level_index"],
             registry
         )
         .unwrap();
 
-        let level_compact_read_next = register_gauge_vec_with_registry!(
+        let level_compact_read_next = register_counter_vec_with_registry!(
             "storage_level_compact_read_next",
             "GBs read from next level during history compactions to next level",
             &["level_index"],
             registry
         )
         .unwrap();
 
-        let level_compact_write = register_gauge_vec_with_registry!(
+        let level_compact_write = register_counter_vec_with_registry!(
             "storage_level_compact_write",
             "GBs written into next level during history compactions to next level",
             &["level_index"],
             registry
         )
         .unwrap();
 
-        let level_compact_read_sstn_curr = register_int_gauge_vec_with_registry!(
+        let level_compact_read_sstn_curr = register_int_counter_vec_with_registry!(
             "storage_level_compact_read_sstn_curr",
             "num of SSTs read from current level during history compactions to next level",
             &["level_index"],
             registry
         )
         .unwrap();
 
-        let level_compact_read_sstn_next = register_int_gauge_vec_with_registry!(
+        let level_compact_read_sstn_next = register_int_counter_vec_with_registry!(
             "storage_level_compact_read_sstn_next",
             "num of SSTs read from next level during history compactions to next level",
             &["level_index"],
             registry
         )
         .unwrap();
 
-        let level_compact_write_sstn = register_int_gauge_vec_with_registry!(
+        let level_compact_write_sstn = register_int_counter_vec_with_registry!(
             "storage_level_compact_write_sstn",
             "num of SSTs written into next level during history compactions to next level",
             &["level_index"],