Update custom Gauges to Micrometer MeterBinders

service/src/main/java/org/whispersystems/textsecuregcm/metrics/FreeMemoryGauge.java

@@ -5,10 +5,15 @@
 
 package org.whispersystems.textsecuregcm.metrics;
 
+import static org.whispersystems.textsecuregcm.metrics.MetricsUtil.name;
+
 import com.sun.management.OperatingSystemMXBean;
+import io.micrometer.core.instrument.Gauge;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.binder.MeterBinder;
 import java.lang.management.ManagementFactory;
 
-public class FreeMemoryGauge implements Gauge {
+public class FreeMemoryGauge implements MeterBinder {
 
   private final OperatingSystemMXBean operatingSystemMXBean;
 
@@ -18,7 +23,10 @@ public class FreeMemoryGauge implements Gauge {
   }
 
   @Override
-  public double getValue() {
+  public void bindTo(final MeterRegistry registry) {
-    return operatingSystemMXBean.getFreeMemorySize();
+    Gauge.builder(name(FreeMemoryGauge.class, "freeMemory"), operatingSystemMXBean,
+            OperatingSystemMXBean::getFreeMemorySize)
+        .register(registry);
+
   }
 }

service/src/main/java/org/whispersystems/textsecuregcm/metrics/Gauge.java

@@ -1,11 +0,0 @@
-/*
- * Copyright 2024 Signal Messenger, LLC
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-package org.whispersystems.textsecuregcm.metrics;
-
-interface Gauge {
-
-  double getValue();
-}

service/src/main/java/org/whispersystems/textsecuregcm/metrics/MetricsUtil.java

@@ -105,10 +105,10 @@ public class MetricsUtil {
 
   public static void registerSystemResourceMetrics(final Environment environment) {
     new ProcessorMetrics().bindTo(Metrics.globalRegistry);
-    registerGauge(name(FreeMemoryGauge.class, "freeMemory"), new FreeMemoryGauge());
+    new FreeMemoryGauge().bindTo(Metrics.globalRegistry);
     new FileDescriptorMetrics().bindTo(Metrics.globalRegistry);
-    registerGauge(name(OperatingSystemMemoryGauge.class, "buffers"), new OperatingSystemMemoryGauge("Buffers"));
+    new OperatingSystemMemoryGauge("Buffers").bindTo(Metrics.globalRegistry);
-    registerGauge(name(OperatingSystemMemoryGauge.class, "cached"), new OperatingSystemMemoryGauge("Cached"));
+    new OperatingSystemMemoryGauge("Cached").bindTo(Metrics.globalRegistry);
 
     new JvmMemoryMetrics().bindTo(Metrics.globalRegistry);
     new JvmThreadMetrics().bindTo(Metrics.globalRegistry);
@@ -116,8 +116,4 @@ public class MetricsUtil {
     GarbageCollectionGauges.registerMetrics();
   }
 
-  private static void registerGauge(final String name, final Gauge gauge) {
-    Metrics.gauge(name, gauge, Gauge::getValue);
-  }
-
 }

service/src/main/java/org/whispersystems/textsecuregcm/metrics/OperatingSystemMemoryGauge.java

@@ -5,16 +5,22 @@
 
 package org.whispersystems.textsecuregcm.metrics;
 
+import static org.whispersystems.textsecuregcm.metrics.MetricsUtil.name;
+
 import com.google.common.annotations.VisibleForTesting;
+import io.micrometer.core.instrument.Gauge;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.binder.MeterBinder;
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
+import java.util.Locale;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Stream;
 
-public class OperatingSystemMemoryGauge implements Gauge {
+public class OperatingSystemMemoryGauge implements MeterBinder {
 
   private final String metricName;
 
@@ -26,19 +32,23 @@ public class OperatingSystemMemoryGauge implements Gauge {
   }
 
   @Override
-  public double getValue() {
+  public void bindTo(MeterRegistry registry) {
-    try (final BufferedReader bufferedReader = new BufferedReader(new FileReader(MEMINFO_FILE))) {
+    final String metricName = this.metricName;
-      return getValue(bufferedReader.lines());
+    Gauge.builder(name(OperatingSystemMemoryGauge.class, metricName.toLowerCase(Locale.ROOT)), () -> {
-    } catch (final IOException e) {
+          try (final BufferedReader bufferedReader = new BufferedReader(new FileReader(MEMINFO_FILE))) {
-      return 0L;
+            return getValue(bufferedReader.lines(), metricName);
-    }
+          } catch (final IOException e) {
+            return 0L;
+          }
+        })
+        .register(registry);
   }
 
   @VisibleForTesting
-  double getValue(final Stream<String> lines) {
+  static double getValue(final Stream<String> lines, final String metricName) {
     return lines.map(MEMORY_METRIC_PATTERN::matcher)
         .filter(Matcher::matches)
-        .filter(matcher -> this.metricName.equalsIgnoreCase(matcher.group(1)))
+        .filter(matcher -> metricName.equalsIgnoreCase(matcher.group(1)))
         .map(matcher -> Double.parseDouble(matcher.group(2)))
         .findFirst()
         .orElse(0d);

service/src/test/java/org/whispersystems/textsecuregcm/metrics/OperatingSystemMemoryGaugeTest.java

@@ -75,7 +75,7 @@ class OperatingSystemMemoryGaugeTest {
   @ParameterizedTest
   @MethodSource
   void testGetValue(final String metricName, final long expectedValue) {
-    assertEquals(expectedValue, new OperatingSystemMemoryGauge(metricName).getValue(MEMINFO.lines()));
+    assertEquals(expectedValue, OperatingSystemMemoryGauge.getValue(MEMINFO.lines(), metricName));
   }
 
   @SuppressWarnings("unused")