Use a feature flag to decide whether logs should be printed to logcat or not

This is done so it can be temporarily enabled on release builds for quick debugging sessions, then disabled again.

app/src/main/kotlin/io/element/android/x/di/AppBindings.kt

@@ -16,6 +16,7 @@ import io.element.android.features.rageshake.api.reporter.BugReporter
 import io.element.android.libraries.core.meta.BuildMeta
 import io.element.android.libraries.designsystem.utils.snackbar.SnackbarDispatcher
 import io.element.android.libraries.di.AppScope
+import io.element.android.libraries.featureflag.api.FeatureFlagService
 import io.element.android.libraries.matrix.api.tracing.TracingService
 import io.element.android.libraries.preferences.api.store.AppPreferencesStore
 import io.element.android.services.analytics.api.AnalyticsService
@@ -40,5 +41,7 @@ interface AppBindings {
 
     fun enterpriseService(): EnterpriseService
 
+    fun featureFlagService(): FeatureFlagService
+
     fun buildMeta(): BuildMeta
 }

app/src/main/kotlin/io/element/android/x/initializer/TracingInitializer.kt

@@ -12,6 +12,7 @@ import android.system.Os
 import androidx.startup.Initializer
 import io.element.android.features.rageshake.api.reporter.BugReporter
 import io.element.android.libraries.architecture.bindings
+import io.element.android.libraries.featureflag.api.FeatureFlags
 import io.element.android.libraries.matrix.api.tracing.TracingConfiguration
 import io.element.android.libraries.matrix.api.tracing.WriteToFilesConfiguration
 import io.element.android.x.di.AppBindings
@@ -28,9 +29,10 @@ class TracingInitializer : Initializer<Unit> {
         val bugReporter = appBindings.bugReporter()
         Timber.plant(tracingService.createTimberTree(ELEMENT_X_TARGET))
         val preferencesStore = appBindings.preferencesStore()
+        val featureFlagService = appBindings.featureFlagService()
         val logLevel = runBlocking { preferencesStore.getTracingLogLevelFlow().first() }
         val tracingConfiguration = TracingConfiguration(
-            writesToLogcat = true,
+            writesToLogcat = runBlocking { featureFlagService.isFeatureEnabled(FeatureFlags.PrintLogsToLogcat) },
             writesToFilesConfiguration = defaultWriteToDiskConfiguration(bugReporter),
             logLevel = logLevel,
             extraTargets = listOf(ELEMENT_X_TARGET),

libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt

@@ -168,4 +168,14 @@ enum class FeatureFlags(
         defaultValue = { true },
         isFinished = false,
     ),
+    PrintLogsToLogcat(
+        key = "feature.print_logs_to_logcat",
+        title = "Print logs to logcat",
+        description = "Print logs to logcat in addition to log files. Requires an app restart to take effect." +
+            "\n\nWARNING: this will make the logs visible in the device logs and may affect performance. " +
+            "It's not intended for daily usage in release builds.",
+        defaultValue = { buildMeta -> buildMeta.buildType != BuildType.RELEASE },
+        // False so it's displayed in the developer options screen
+        isFinished = false,
+    )
 }