Add fragment trace sampling rate config flag

firebase-perf/src/main/java/com/google/firebase/perf/config/ConfigResolver.java

@@ -23,6 +23,7 @@
 import com.google.firebase.perf.BuildConfig;
 import com.google.firebase.perf.config.ConfigurationConstants.CollectionDeactivated;
 import com.google.firebase.perf.config.ConfigurationConstants.CollectionEnabled;
+import com.google.firebase.perf.config.ConfigurationConstants.FragmentSamplingRate;
 import com.google.firebase.perf.config.ConfigurationConstants.LogSourceName;
 import com.google.firebase.perf.config.ConfigurationConstants.NetworkEventCountBackground;
 import com.google.firebase.perf.config.ConfigurationConstants.NetworkEventCountForeground;
@@ -729,6 +730,43 @@ public String getAndCacheLogSourceName() {
     return configFlag.getDefault();
   }
 
+  /** Returns what percentage of fragment traces should be collected, range is [0.00f, 1.00f]. */
+  public float getFragmentSamplingRate() {
+    // Order of precedence is:
+    // 1. If the value exists in Android Manifest, convert from [0.00f, 100.00f] to [0.00f, 1.00f]
+    // and return this value.
+    // 2. If the value exists through Firebase Remote Config, cache and return this value.
+    // 3. If the value exists in device cache, return this value.
+    // 4. Otherwise, return default value.
+    FragmentSamplingRate config = FragmentSamplingRate.getInstance();
+
+    // 1. Reads value in Android Manifest (it is set by developers during build time).
+    Optional<Float> metadataValue = getMetadataFloat(config);
+    if (metadataValue.isAvailable()) {
+      // Sampling percentage from metadata needs to convert from [0.00f, 100.00f] to [0.00f, 1.00f].
+      float samplingRate = metadataValue.get() / 100.0f;
+      if (isSamplingRateValid(samplingRate)) {
+        return samplingRate;
+      }
+    }
+
+    // 2. Reads value from Firebase Remote Config, saves this value in cache layer if valid.
+    Optional<Float> rcValue = getRemoteConfigFloat(config);
+    if (rcValue.isAvailable() && isSamplingRateValid(rcValue.get())) {
+      deviceCacheManager.setValue(config.getDeviceCacheFlag(), rcValue.get());
+      return rcValue.get();
+    }
+
+    // 3. Reads value from cache layer.
+    Optional<Float> deviceCacheValue = getDeviceCacheFloat(config);
+    if (deviceCacheValue.isAvailable() && isSamplingRateValid(deviceCacheValue.get())) {
+      return deviceCacheValue.get();
+    }
+
+    // 4. Returns default value if there is no valid value from above approaches.
+    return config.getDefault();
+  }
+
   // endregion
 
   // Helper functions for interaction with Metadata layer.

firebase-perf/src/main/java/com/google/firebase/perf/config/ConfigurationConstants.java

@@ -623,4 +623,42 @@ protected String getDeviceCacheFlag() {
       return "com.google.firebase.perf.LogSourceName";
     }
   }
+
+  protected static final class FragmentSamplingRate extends ConfigurationFlag<Float> {
+    private static FragmentSamplingRate instance;
+
+    private FragmentSamplingRate() {
+      super();
+    }
+
+    protected static synchronized FragmentSamplingRate getInstance() {
+      if (instance == null) {
+        instance = new FragmentSamplingRate();
+      }
+      return instance;
+    }
+
+    @Override
+    protected Float getDefault() {
+      // Sampling rate range is [0.00f, 1.00f]. By default, sampling rate is 1.00f, which is 100%.
+      // 0.00f means 0%, Fireperf will not capture any event for fragment trace from the device,
+      // 1.00f means 100%, Fireperf will capture all events for fragment trace from the device.
+      return 1.00f;
+    }
+
+    @Override
+    protected String getRemoteConfigFlag() {
+      return "fpr_vc_fragment_sampling_rate";
+    }
+
+    @Override
+    protected String getDeviceCacheFlag() {
+      return "com.google.firebase.perf.FragmentSamplingRate";
+    }
+
+    @Override
+    protected String getMetadataFlag() {
+      return "fragment_sampling_percentage";
+    }
+  }
 }

firebase-perf/src/test/java/com/google/firebase/perf/config/ConfigResolverTest.java

@@ -126,6 +126,11 @@ public class ConfigResolverTest extends FirebasePerformanceTestBase {
   private static final String SESSIONS_MAX_DURATION_MIN_CACHE_KEY =
       "com.google.firebase.perf.SessionsMaxDurationMinutes";
 
+  // Fragment trace sampling rate flags
+  private static final String FRAGMENT_SAMPLING_RATE_FRC_KEY = "fpr_vc_fragment_sampling_rate";
+  private static final String FRAGMENT_SAMPLING_RATE_CACHE_KEY =
+      "com.google.firebase.perf.FragmentSamplingRate";
+
   private ConfigResolver testConfigResolver;
 
   @Mock private RemoteConfigManager mockRemoteConfigManager;
@@ -2482,4 +2487,237 @@ public void getAndCacheLogSourceName_invalidRemoteConfigData_returnsCache() {
     verify(mockDeviceCacheManager, times(1))
         .setValue(eq("com.google.firebase.perf.LogSourceName"), eq("FIREPERF_INTERNAL_LOW"));
   }
+
+  @Test
+  public void getFragmentSamplingRate_validMetadata_returnsMetadata() {
+    // #1 pass: Validate that method returns Remote Config Value when there is no metadata value.
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.of(0.01f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.01f);
+
+    // #2 pass: Validate that method returns Metadata value which takes higher precedence.
+    Bundle bundle = new Bundle();
+    bundle.putFloat("fragment_sampling_percentage", 20.0f);
+    testConfigResolver.setMetadataBundle(new ImmutableBundle(bundle));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.2f);
+  }
+
+  @Test
+  public void getFragmentSamplingRate_validMetadata_notSaveMetadataInCache() {
+    Bundle bundle = new Bundle();
+    bundle.putFloat("fragment_sampling_percentage", 20.0f);
+    testConfigResolver.setMetadataBundle(new ImmutableBundle(bundle));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.2f);
+
+    verify(mockDeviceCacheManager, never()).setValue(any(), any());
+  }
+
+  @Test
+  public void getFragmentSamplingRate_invalidAndroidMetadataBundle_returnDefaultValue() {
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.absent());
+    when(mockDeviceCacheManager.getFloat(FRAGMENT_SAMPLING_RATE_CACHE_KEY))
+        .thenReturn(Optional.absent());
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(1.0f);
+
+    // Case #1: Android Metadata bundle value is too high.
+    Bundle bundle = new Bundle();
+    bundle.putFloat("fragment_sampling_percentage", 200.00f);
+    testConfigResolver.setMetadataBundle(new ImmutableBundle(bundle));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(1.0f);
+
+    // Case #2: Android Metadata bundle value is too low.
+    bundle = new Bundle();
+    bundle.putFloat("fragment_sampling_percentage", -1.00f);
+    testConfigResolver.setMetadataBundle(new ImmutableBundle(bundle));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(1.0f);
+  }
+
+  @Test
+  public void getFragmentSamplingRate_invalidAndroidMetadataBundle_returnRemoteConfigValue() {
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.of(0.25f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.25f);
+
+    // Case #1: Android Metadata bundle value is too high.
+    Bundle bundle = new Bundle();
+    bundle.putFloat("fragment_sampling_percentage", 200.00f);
+    testConfigResolver.setMetadataBundle(new ImmutableBundle(bundle));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.25f);
+
+    // Case #2: Android Metadata bundle value is too low.
+    bundle = new Bundle();
+    bundle.putFloat("fragment_sampling_percentage", -1.00f);
+    testConfigResolver.setMetadataBundle(new ImmutableBundle(bundle));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.25f);
+  }
+
+  @Test
+  public void getFragmentSamplingRate_invalidMetadataBundle_returnCacheValue() {
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.absent());
+    when(mockDeviceCacheManager.getFloat(FRAGMENT_SAMPLING_RATE_CACHE_KEY))
+        .thenReturn(Optional.of(1.0f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(1.0f);
+
+    // Case #1: Android Metadata bundle value is too high.
+    Bundle bundle = new Bundle();
+    bundle.putFloat("fragment_sampling_percentage", 200.00f);
+    testConfigResolver.setMetadataBundle(new ImmutableBundle(bundle));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(1.0f);
+
+    // Case #2: Android Metadata bundle value is too low.
+    bundle = new Bundle();
+    bundle.putFloat("fragment_sampling_percentage", -1.00f);
+    testConfigResolver.setMetadataBundle(new ImmutableBundle(bundle));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(1.0f);
+  }
+
+  @Test
+  public void getFragmentSamplingRate_validRemoteConfig_returnRemoteConfigValue() {
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.of(0.25f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.25f);
+    verify(mockDeviceCacheManager, times(1))
+        .setValue(eq(FRAGMENT_SAMPLING_RATE_CACHE_KEY), eq(0.25f));
+
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.of(0.0f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.0f);
+    verify(mockDeviceCacheManager, times(1))
+        .setValue(eq(FRAGMENT_SAMPLING_RATE_CACHE_KEY), eq(0.0f));
+
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.of(0.00005f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.00005f);
+    verify(mockDeviceCacheManager, times(1))
+        .setValue(eq(FRAGMENT_SAMPLING_RATE_CACHE_KEY), eq(0.00005f));
+
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.of(0.0000000001f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.0000000001f);
+    verify(mockDeviceCacheManager, times(1))
+        .setValue(eq(FRAGMENT_SAMPLING_RATE_CACHE_KEY), eq(0.0000000001f));
+  }
+
+  @Test
+  public void getFragmentSamplingRate_invalidRemoteConfig_returnDefaultValue() {
+    // Mock behavior that device cache doesn't have session sampling rate value.
+    when(mockDeviceCacheManager.getFloat(FRAGMENT_SAMPLING_RATE_CACHE_KEY))
+        .thenReturn(Optional.absent());
+
+    // Case #1: Firebase Remote Config value is too high.
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.of(1.01f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(1.0f);
+    verify(mockDeviceCacheManager, never()).setValue(any(), any());
+
+    // Case #2: Firebase Remote Config value is too low.
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.of(-0.1f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(1.0f);
+    verify(mockDeviceCacheManager, never()).setValue(any(), any());
+  }
+
+  @Test
+  public void getFragmentSamplingRate_invalidRemoteConfig_returnCacheValue() {
+    // Mock behavior that device cache doesn't have session sampling rate value.
+    when(mockDeviceCacheManager.getFloat(FRAGMENT_SAMPLING_RATE_CACHE_KEY))
+        .thenReturn(Optional.of(0.25f));
+
+    // Case #1: Firebase Remote Config value is too high.
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.of(1.01f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.25f);
+    verify(mockDeviceCacheManager, never()).setValue(any(), any());
+
+    // Case #2: Firebase Remote Config value is too low.
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.of(-0.1f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.25f);
+    verify(mockDeviceCacheManager, never()).setValue(any(), any());
+  }
+
+  @Test
+  public void getFragmentSamplingRate_validCache_returnCacheValue() {
+    when(mockDeviceCacheManager.getFloat(FRAGMENT_SAMPLING_RATE_CACHE_KEY))
+        .thenReturn(Optional.of(1.0f));
+
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.absent());
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(1.0f);
+  }
+
+  @Test
+  public void getFragmentSamplingRate_invalidCache_returnDefaultValue() {
+    // Mock behavior that remote config doesn't have session sampling rate value.
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.absent());
+
+    // Case #1: Device Cache value is too high.
+    when(mockDeviceCacheManager.getFloat(FRAGMENT_SAMPLING_RATE_CACHE_KEY))
+        .thenReturn(Optional.of(10.0f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(1.0f);
+
+    // Case #2: Device Cache value is too low.
+    when(mockDeviceCacheManager.getFloat(FRAGMENT_SAMPLING_RATE_CACHE_KEY))
+        .thenReturn(Optional.of(-1.0f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(1.0f);
+  }
+
+  @Test
+  public void
+      getFragmentSamplingRate_metadataAndRemoteConfigAndCacheAreSet_metadataHasHighestConfigPrecedence() {
+    // Set cache value.
+    when(mockDeviceCacheManager.getFloat(FRAGMENT_SAMPLING_RATE_CACHE_KEY))
+        .thenReturn(Optional.of(0.2f));
+
+    // Set remote config value.
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.of(0.3f));
+
+    // Set Android Manifest value.
+    Bundle bundle = new Bundle();
+    bundle.putFloat("fragment_sampling_percentage", 4.0f);
+    testConfigResolver.setMetadataBundle(new ImmutableBundle(bundle));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.04f);
+  }
+
+  @Test
+  public void
+      getFragmentSamplingRate_remoteConfigAndCacheAreSet_remoteConfigHasHighestConfigPrecedence() {
+    // Set cache value.
+    when(mockDeviceCacheManager.getFloat(FRAGMENT_SAMPLING_RATE_CACHE_KEY))
+        .thenReturn(Optional.of(0.2f));
+
+    // Set remote config value.
+    when(mockRemoteConfigManager.getFloat(FRAGMENT_SAMPLING_RATE_FRC_KEY))
+        .thenReturn(Optional.of(0.3f));
+
+    assertThat(testConfigResolver.getFragmentSamplingRate()).isEqualTo(0.3f);
+  }
 }

firebase-perf/src/test/java/com/google/firebase/perf/config/ConfigurationConstantsTest.java

@@ -18,6 +18,7 @@
 
 import com.google.firebase.perf.config.ConfigurationConstants.CollectionDeactivated;
 import com.google.firebase.perf.config.ConfigurationConstants.CollectionEnabled;
+import com.google.firebase.perf.config.ConfigurationConstants.FragmentSamplingRate;
 import com.google.firebase.perf.config.ConfigurationConstants.LogSourceName;
 import com.google.firebase.perf.config.ConfigurationConstants.NetworkEventCountBackground;
 import com.google.firebase.perf.config.ConfigurationConstants.NetworkEventCountForeground;
@@ -253,4 +254,15 @@ public void getInstance_LogSourceName_validateConstants() {
     assertThat(LogSourceName.getLogSourceName(675L)).isEqualTo("FIREPERF_INTERNAL_LOW");
     assertThat(LogSourceName.getLogSourceName(676L)).isEqualTo("FIREPERF_INTERNAL_HIGH");
   }
+
+  @Test
+  public void getInstance_FragmentSamplingRate_validateConstants() {
+    FragmentSamplingRate configFlag = FragmentSamplingRate.getInstance();
+
+    assertThat(configFlag.getDefault()).isEqualTo(1.0f);
+    assertThat(configFlag.getDeviceCacheFlag())
+        .isEqualTo("com.google.firebase.perf.FragmentSamplingRate");
+    assertThat(configFlag.getRemoteConfigFlag()).isEqualTo("fpr_vc_fragment_sampling_rate");
+    assertThat(configFlag.getMetadataFlag()).isEqualTo("fragment_sampling_percentage");
+  }
 }