Code review

Author: tejasd

firebase-perf/src/main/java/com/google/firebase/perf/session/gauges/CpuGaugeCollector.java

@@ -166,7 +166,7 @@ private synchronized void scheduleCpuMetricCollectionWithRate(
                 CpuMetricReading currCpuReading = syncCollectCpuMetric(referenceTime);
                 if (currCpuReading != null) {
                   cpuMetricReadings.add(currCpuReading);
-                  GaugeCounter.Companion.getInstance().incrementCounter();
+                  GaugeCounter.INSTANCE.incrementCounter();
                 }
               },
               /* initialDelay */ 0,

firebase-perf/src/main/java/com/google/firebase/perf/session/gauges/GaugeCounter.kt

@@ -17,10 +17,11 @@ package com.google.firebase.perf.session.gauges
 import java.util.concurrent.atomic.AtomicInteger
 
 /**
- * [GaugeCounter] is a threadsafe counter for gauge metrics. If the metrics count exceeds
+ * [GaugeCounter] is a thread-safe counter for gauge metrics. If the metrics count exceeds
  * [MAX_METRIC_COUNT], it attempts to log the metrics to Firelog.
  */
-class GaugeCounter private constructor() {
+object GaugeCounter {
+  private const val MAX_METRIC_COUNT = 25
   private val counter = AtomicInteger(0)
   private val gaugeManager: GaugeManager = GaugeManager.getInstance()
 
@@ -35,9 +36,4 @@ class GaugeCounter private constructor() {
   fun decrementCounter() {
     counter.decrementAndGet()
   }
-
-  companion object {
-    val instance: GaugeCounter by lazy(LazyThreadSafetyMode.SYNCHRONIZED) { GaugeCounter() }
-    const val MAX_METRIC_COUNT = 25
-  }
 }

firebase-perf/src/main/java/com/google/firebase/perf/session/gauges/GaugeManager.java

@@ -243,7 +243,7 @@ private void logExistingGaugeMetrics(
    */
   private void syncFlush(String sessionId, ApplicationProcessState appState) {
     GaugeMetric.Builder gaugeMetricBuilder = GaugeMetric.newBuilder();
-    GaugeCounter gaugeCounter = GaugeCounter.Companion.getInstance();
+    GaugeCounter gaugeCounter = GaugeCounter.INSTANCE;
 
     // Adding CPU metric readings.
     while (!cpuGaugeCollector.get().cpuMetricReadings.isEmpty()) {

firebase-perf/src/main/java/com/google/firebase/perf/session/gauges/MemoryGaugeCollector.java

@@ -129,7 +129,7 @@ private synchronized void scheduleMemoryMetricCollectionWithRate(
                 AndroidMemoryReading memoryReading = syncCollectMemoryMetric(referenceTime);
                 if (memoryReading != null) {
                   memoryMetricReadings.add(memoryReading);
-                  GaugeCounter.Companion.getInstance().incrementCounter();
+                  GaugeCounter.INSTANCE.incrementCounter();
                 }
               },
               /* initialDelay */ 0,

firebase-perf/src/test/java/com/google/firebase/perf/session/gauges/GaugeManagerTest.java

@@ -159,12 +159,14 @@ public void testStartCollectingGaugesStartsCollectingMetricsInForegroundState()
       testStartCollectingGaugesStartCollectingMetricsWithUnknownApplicationProcessStateInForegroundState() {
     PerfSession fakeSession = createTestSession(1);
     testGaugeManager.startCollectingGauges(fakeSession);
-    // @see
-    // com.google.firebase.perf.config.ConfigurationConstants.SessionsCpuCaptureFrequencyForegroundMs
     verify(fakeCpuGaugeCollector, never())
-        .startCollecting(ArgumentMatchers.eq(100L), ArgumentMatchers.nullable(Timer.class));
+        .startCollecting(
+            eq(DEFAULT_CPU_GAUGE_COLLECTION_FREQUENCY_FG_MS),
+            ArgumentMatchers.nullable(Timer.class));
     verify(fakeMemoryGaugeCollector, never())
-        .startCollecting(ArgumentMatchers.eq(100L), ArgumentMatchers.nullable(Timer.class));
+        .startCollecting(
+            eq(DEFAULT_CPU_GAUGE_COLLECTION_FREQUENCY_FG_MS),
+            ArgumentMatchers.nullable(Timer.class));
   }
 
   @Test