Refactor session handling

core/build.gradle.kts

@@ -69,6 +69,7 @@ dependencies {
     api(platform(libs.opentelemetry.platform))
     api(libs.opentelemetry.api)
     implementation(libs.opentelemetry.sdk)
+    implementation(libs.opentelemetry.api.incubator)
     implementation(libs.opentelemetry.exporter.logging)
     implementation(libs.opentelemetry.instrumentation.api)
     implementation(libs.opentelemetry.semconv.incubating)

core/src/main/java/io/opentelemetry/android/OpenTelemetryRumBuilder.java

@@ -23,6 +23,8 @@
 import io.opentelemetry.android.internal.services.CacheStorage;
 import io.opentelemetry.android.internal.services.Preferences;
 import io.opentelemetry.android.internal.services.ServiceManager;
+import io.opentelemetry.android.session.SessionManager;
+import io.opentelemetry.android.session.SessionProvider;
 import io.opentelemetry.api.baggage.propagation.W3CBaggagePropagator;
 import io.opentelemetry.api.trace.propagation.W3CTraceContextPropagator;
 import io.opentelemetry.context.propagation.ContextPropagators;
@@ -65,7 +67,6 @@
  */
 public final class OpenTelemetryRumBuilder {
 
-    private final SessionId sessionId;
     private final Application application;
     private final List<BiFunction<SdkTracerProviderBuilder, Application, SdkTracerProviderBuilder>>
             tracerProviderCustomizers = new ArrayList<>();
@@ -76,6 +77,7 @@ public final class OpenTelemetryRumBuilder {
     private final OtelRumConfig config;
     private final List<AndroidInstrumentation> instrumentations = new ArrayList<>();
     private final List<Consumer<OpenTelemetrySdk>> otelSdkReadyListeners = new ArrayList<>();
+    private final SessionIdTimeoutHandler timeoutHandler;
     private Function<? super SpanExporter, ? extends SpanExporter> spanExporterCustomizer = a -> a;
     private Function<? super LogRecordExporter, ? extends LogRecordExporter>
             logRecordExporterCustomizer = a -> a;
@@ -97,7 +99,7 @@ public static OpenTelemetryRumBuilder create(Application application, OtelRumCon
     OpenTelemetryRumBuilder(
             Application application, OtelRumConfig config, SessionIdTimeoutHandler timeoutHandler) {
         this.application = application;
-        this.sessionId = new SessionId(timeoutHandler);
+        this.timeoutHandler = timeoutHandler;
         this.resource = AndroidResource.createDefault(application);
         this.config = config;
     }
@@ -253,10 +255,6 @@ public OpenTelemetryRumBuilder addLogRecordExporterCustomizer(
         return this;
     }
 
-    public SessionId getSessionId() {
-        return sessionId;
-    }
-
     /**
      * Creates a new instance of {@link OpenTelemetryRum} with the settings of this {@link
      * OpenTelemetryRumBuilder}.
@@ -303,10 +301,13 @@ OpenTelemetryRum build(ServiceManager serviceManager) {
         }
         initializationEvents.spanExporterInitialized(spanExporter);
 
+        SessionManager sessionManager =
+                SessionManager.create(timeoutHandler, config.getSessionTimeout().toNanos());
+
         OpenTelemetrySdk sdk =
                 OpenTelemetrySdk.builder()
                         .setTracerProvider(
-                                buildTracerProvider(sessionId, application, spanExporter))
+                                buildTracerProvider(sessionManager, application, spanExporter))
                         .setMeterProvider(buildMeterProvider(application))
                         .setLoggerProvider(buildLoggerProvider(application, logsExporter))
                         .setPropagators(buildFinalPropagators())
@@ -320,7 +321,8 @@ OpenTelemetryRum build(ServiceManager serviceManager) {
                 new SdkPreconfiguredRumBuilder(
                         application,
                         sdk,
-                        sessionId,
+                        timeoutHandler,
+                        sessionManager,
                         config.shouldDiscoverInstrumentations(),
                         serviceManager);
         instrumentations.forEach(delegate::addInstrumentation);
@@ -417,11 +419,11 @@ private void applyConfiguration(
     }
 
     private SdkTracerProvider buildTracerProvider(
-            SessionId sessionId, Application application, SpanExporter spanExporter) {
+            SessionProvider sessionProvider, Application application, SpanExporter spanExporter) {
         SdkTracerProviderBuilder tracerProviderBuilder =
                 SdkTracerProvider.builder()
                         .setResource(resource)
-                        .addSpanProcessor(new SessionIdSpanAppender(sessionId));
+                        .addSpanProcessor(new SessionIdSpanAppender(sessionProvider));
 
         BatchSpanProcessor batchSpanProcessor = BatchSpanProcessor.builder(spanExporter).build();
         tracerProviderBuilder.addSpanProcessor(batchSpanProcessor);

core/src/main/java/io/opentelemetry/android/OpenTelemetryRumImpl.java

@@ -5,17 +5,18 @@
 
 package io.opentelemetry.android;
 
+import io.opentelemetry.android.session.SessionManager;
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.sdk.OpenTelemetrySdk;
 
 final class OpenTelemetryRumImpl implements OpenTelemetryRum {
 
     private final OpenTelemetrySdk openTelemetrySdk;
-    private final SessionId sessionId;
+    private final SessionManager sessionManager;
 
-    OpenTelemetryRumImpl(OpenTelemetrySdk openTelemetrySdk, SessionId sessionId) {
+    OpenTelemetryRumImpl(OpenTelemetrySdk openTelemetrySdk, SessionManager sessionManager) {
         this.openTelemetrySdk = openTelemetrySdk;
-        this.sessionId = sessionId;
+        this.sessionManager = sessionManager;
     }
 
     @Override
@@ -25,6 +26,6 @@ public OpenTelemetry getOpenTelemetry() {
 
     @Override
     public String getRumSessionId() {
-        return sessionId.getSessionId();
+        return sessionManager.getSessionId();
     }
 }

core/src/main/java/io/opentelemetry/android/SdkPreconfiguredRumBuilder.kt

@@ -9,17 +9,17 @@ import android.app.Application
 import io.opentelemetry.android.instrumentation.AndroidInstrumentation
 import io.opentelemetry.android.instrumentation.AndroidInstrumentationLoader
 import io.opentelemetry.android.internal.services.ServiceManager
+import io.opentelemetry.android.session.SessionManager
 import io.opentelemetry.sdk.OpenTelemetrySdk
+import io.opentelemetry.sdk.logs.internal.SdkEventLoggerProvider
 
 class SdkPreconfiguredRumBuilder
     @JvmOverloads
     internal constructor(
         private val application: Application,
         private val sdk: OpenTelemetrySdk,
-        private val sessionId: SessionId =
-            SessionId(
-                SessionIdTimeoutHandler(),
-            ),
+        private val timeoutHandler: SessionIdTimeoutHandler = SessionIdTimeoutHandler(),
+        private val sessionManager: SessionManager = SessionManager(timeoutHandler = timeoutHandler),
         private val discoverInstrumentations: Boolean,
         private val serviceManager: ServiceManager,
     ) {
@@ -49,12 +49,17 @@ class SdkPreconfiguredRumBuilder
             serviceManager.start()
             // the app state listeners need to be run in the first ActivityLifecycleCallbacks since they
             // might turn off/on additional telemetry depending on whether the app is active or not
-            appLifecycleService.registerListener(sessionId.timeoutHandler)
+            appLifecycleService.registerListener(timeoutHandler)
 
-            val tracer = sdk.getTracer(OpenTelemetryRum::class.java.simpleName)
-            sessionId.setSessionIdChangeListener(SessionIdChangeTracer(tracer))
+            val eventLogger =
+                SdkEventLoggerProvider.create(sdk.logsBridge)
+                    .get(OpenTelemetryRum::class.java.simpleName)
 
-            val openTelemetryRum = OpenTelemetryRumImpl(sdk, sessionId)
+            sessionManager.addObserver(SessionIdEventSender(eventLogger))
+            // After addObserver(), we call getSessionId() to trigger a session.start event
+            sessionManager.getSessionId()
+
+            val openTelemetryRum = OpenTelemetryRumImpl(sdk, sessionManager)
 
             // Install instrumentations
             for (instrumentation in getInstrumentations()) {

core/src/main/java/io/opentelemetry/android/SessionIdEventSender.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.android
+
+import io.opentelemetry.android.common.RumConstants.Events.EVENT_SESSION_END
+import io.opentelemetry.android.common.RumConstants.Events.EVENT_SESSION_START
+import io.opentelemetry.android.session.Session
+import io.opentelemetry.android.session.SessionObserver
+import io.opentelemetry.api.incubator.events.EventLogger
+import io.opentelemetry.semconv.incubating.SessionIncubatingAttributes.SESSION_ID
+import io.opentelemetry.semconv.incubating.SessionIncubatingAttributes.SESSION_PREVIOUS_ID
+
+internal class SessionIdEventSender(private val eventLogger: EventLogger) : SessionObserver {
+    override fun onSessionStarted(
+        newSession: Session,
+        previousSession: Session,
+    ) {
+        val eventBuilder =
+            eventLogger
+                .builder(EVENT_SESSION_START)
+                .put(SESSION_ID, newSession.getId())
+        val previousSessionId = previousSession.getId()
+        if (previousSessionId.isNotEmpty()) {
+            eventBuilder.put(SESSION_PREVIOUS_ID, previousSessionId)
+        }
+        eventBuilder.emit()
+    }
+
+    override fun onSessionEnded(session: Session) {
+        if (session.getId().isEmpty()) {
+            return
+        }
+        eventLogger.builder(EVENT_SESSION_END)
+            .put(SESSION_ID, session.getId())
+            .emit()
+    }
+}

core/src/main/java/io/opentelemetry/android/SessionIdRatioBasedSampler.java

@@ -5,6 +5,7 @@
 
 package io.opentelemetry.android;
 
+import io.opentelemetry.android.session.SessionProvider;
 import io.opentelemetry.api.common.Attributes;
 import io.opentelemetry.api.trace.SpanKind;
 import io.opentelemetry.context.Context;
@@ -22,10 +23,10 @@
  */
 public class SessionIdRatioBasedSampler implements Sampler {
     private final Sampler ratioBasedSampler;
-    private final SessionId sessionId;
+    private final SessionProvider sessionProvider;
 
-    public SessionIdRatioBasedSampler(double ratio, SessionId sessionId) {
-        this.sessionId = sessionId;
+    public SessionIdRatioBasedSampler(double ratio, SessionProvider sessionProvider) {
+        this.sessionProvider = sessionProvider;
         // SessionId uses the same format as TraceId, so we can reuse trace ID ratio sampler.
         this.ratioBasedSampler = Sampler.traceIdRatioBased(ratio);
     }
@@ -40,7 +41,12 @@ public SamplingResult shouldSample(
             List<LinkData> parentLinks) {
         // Replace traceId with sessionId
         return ratioBasedSampler.shouldSample(
-                parentContext, sessionId.getSessionId(), name, spanKind, attributes, parentLinks);
+                parentContext,
+                sessionProvider.getSessionId(),
+                name,
+                spanKind,
+                attributes,
+                parentLinks);
     }
 
     @Override