refactor: Update context tracking using lifecycle callbacks (#238)

example/src/main/AndroidManifest.xml

@@ -6,7 +6,6 @@
 
   <uses-permission android:name="android.permission.INTERNET" />
   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
-  <uses-permission android:name="android.permission.GET_TASKS" />
 
   <application
     android:name=".ExampleApplication"

sdk/src/androidTest/AndroidManifest.xml

@@ -5,7 +5,6 @@
   android:versionName="1.0">
 
   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
-  <uses-permission android:name="android.permission.GET_TASKS" />
 
   <application android:label="Bugsnag Android Tests"></application>
 

sdk/src/androidTest/java/com/bugsnag/android/SessionTrackerTest.java

@@ -1,14 +1,13 @@
 package com.bugsnag.android;
 
-import android.support.test.InstrumentationRegistry;
-import android.util.Pair;
-
 import org.junit.Before;
 import org.junit.Test;
 
 import java.util.Date;
 
-import static com.bugsnag.android.BugsnagTestUtils.*;
+import static com.bugsnag.android.BugsnagTestUtils.generateClient;
+import static com.bugsnag.android.BugsnagTestUtils.generateSessionStore;
+import static com.bugsnag.android.BugsnagTestUtils.generateSessionTrackingApiClient;
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.assertFalse;
 import static junit.framework.Assert.assertNotNull;
@@ -95,6 +94,7 @@ public void testIncrementCounts() throws Exception {
     public void testBasicInForeground() throws Exception {
         assertFalse(sessionTracker.isInForeground());
         assertNull(sessionTracker.getCurrentSession());
+        assertNull(sessionTracker.getContextActivity());
 
         sessionTracker.updateForegroundTracker(ACTIVITY_NAME, true, System.currentTimeMillis());
         assertTrue(sessionTracker.isInForeground());
@@ -104,13 +104,16 @@ public void testBasicInForeground() throws Exception {
         sessionTracker.updateForegroundTracker("other", true, System.currentTimeMillis());
         assertTrue(sessionTracker.isInForeground());
         assertEquals(firstSession, sessionTracker.getCurrentSession());
+        assertEquals("other", sessionTracker.getContextActivity());
 
         sessionTracker.updateForegroundTracker("other", false, System.currentTimeMillis());
         assertTrue(sessionTracker.isInForeground());
+        assertEquals(ACTIVITY_NAME, sessionTracker.getContextActivity());
 
         sessionTracker.updateForegroundTracker(ACTIVITY_NAME, false, System.currentTimeMillis());
         assertFalse(sessionTracker.isInForeground());
         assertEquals(firstSession, sessionTracker.getCurrentSession());
+        assertNull(sessionTracker.getContextActivity());
     }
 
     @Test
@@ -129,7 +132,10 @@ public void testInForegroundDuration() throws Exception {
         assertEquals(100, sessionTracker.getDurationInForegroundMs(now + 100));
 
         sessionTracker.updateForegroundTracker(ACTIVITY_NAME, false, now);
-        assertEquals(0, sessionTracker.getDurationInForegroundMs(now + 200));
+        assertEquals(200, sessionTracker.getDurationInForegroundMs(now + 200));
+
+        sessionTracker.updateForegroundTracker(ACTIVITY_NAME, false, now);
+        assertEquals(0, sessionTracker.getDurationInForegroundMs(now + 300));
     }
 
     @Test

sdk/src/main/java/com/bugsnag/android/AppData.java

@@ -9,7 +9,6 @@
 import android.support.annotation.Nullable;
 
 import java.io.IOException;
-import java.util.List;
 
 /**
  * Information about the running Android app, including app name, version and release stage.
@@ -80,18 +79,7 @@ private static String getAppName(@NonNull Context appContext) {
 
     @Nullable
     String getActiveScreenClass() {
-        try {
-            ActivityManager activityManager =
-                (ActivityManager) appContext.getSystemService(Context.ACTIVITY_SERVICE);
-            List<ActivityManager.RunningTaskInfo> tasks =
-                activityManager.getRunningTasks(1);
-            ActivityManager.RunningTaskInfo runningTask = tasks.get(0);
-            return runningTask.topActivity.getClassName();
-        } catch (Exception exception) {
-            Logger.warn("Could not get active screen information,"
-                + " we recommend granting the 'android.permission.GET_TASKS' permission");
-        }
-        return null;
+        return sessionTracker.getContextActivity();
     }
 
     /**
@@ -111,10 +99,12 @@ private static Boolean isLowMemory(@NonNull Context appContext) {
         try {
             ActivityManager activityManager =
                 (ActivityManager) appContext.getSystemService(Context.ACTIVITY_SERVICE);
-            ActivityManager.MemoryInfo memInfo = new ActivityManager.MemoryInfo();
-            activityManager.getMemoryInfo(memInfo);
 
-            return memInfo.lowMemory;
+            if (activityManager != null) {
+                ActivityManager.MemoryInfo memInfo = new ActivityManager.MemoryInfo();
+                activityManager.getMemoryInfo(memInfo);
+                return memInfo.lowMemory;
+            }
         } catch (Exception exception) {
             Logger.warn("Could not check lowMemory status");
         }

sdk/src/main/java/com/bugsnag/android/SessionTracker.java

@@ -10,10 +10,13 @@
 import java.util.Collection;
 import java.util.Date;
 import java.util.HashMap;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.UUID;
-import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentLinkedDeque;
+import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.atomic.AtomicLong;
@@ -24,8 +27,8 @@ class SessionTracker implements Application.ActivityLifecycleCallbacks {
     private static final String KEY_LIFECYCLE_CALLBACK = "ActivityLifecycle";
     private static final int DEFAULT_TIMEOUT_MS = 30000;
 
-    private final ConcurrentHashMap<String, Boolean>
-        foregroundActivities = new ConcurrentHashMap<>();
+    private final Collection<String>
+        foregroundActivities = new ConcurrentLinkedQueue<>();
     private final Configuration configuration;
     private final long timeoutMs;
     private final Client client;
@@ -73,7 +76,7 @@ void startNewSession(@NonNull Date date, @Nullable User user, boolean autoCaptur
      * Determines whether or not a session should be tracked. If this is true, the session will be
      * stored and sent to the Bugsnag API, otherwise no action will occur in this method.
      *
-     * @param session      the session
+     * @param session the session
      */
     private void trackSessionIfNeeded(final Session session) {
         boolean notifyForRelease = configuration.shouldNotifyForReleaseStage(getReleaseStage());
@@ -250,7 +253,7 @@ void startFirstSession(Activity activity) {
             long nowMs = System.currentTimeMillis();
             activityFirstStartedAtMs.set(nowMs);
             startNewSession(new Date(nowMs), client.user, true);
-            foregroundActivities.put(getActivityName(activity), true);
+            foregroundActivities.add(getActivityName(activity));
         }
     }
 
@@ -263,9 +266,9 @@ void startFirstSession(Activity activity) {
      * If an activity comes to the foreground and is the only foreground activity, a new session
      * should be started, unless the app is within a timeout period.
      *
-     * @param activityName the activity name
+     * @param activityName     the activity name
      * @param activityStarting whether the activity is being started or not
-     * @param nowMs The current time in ms
+     * @param nowMs            The current time in ms
      */
     void updateForegroundTracker(String activityName, boolean activityStarting, long nowMs) {
         if (activityStarting) {
@@ -279,7 +282,7 @@ void updateForegroundTracker(String activityName, boolean activityStarting, long
                 activityFirstStartedAtMs.set(nowMs);
                 startNewSession(new Date(nowMs), client.user, true);
             }
-            foregroundActivities.put(activityName, true);
+            foregroundActivities.add(activityName);
         } else {
             foregroundActivities.remove(activityName);
             activityLastStoppedAtMs.set(nowMs);
@@ -301,4 +304,17 @@ long getDurationInForegroundMs(long nowMs) {
         return durationMs > 0 ? durationMs : 0;
     }
 
+    @Nullable
+    String getContextActivity() {
+        if (foregroundActivities.isEmpty()) {
+            return null;
+        } else {
+            // linked hash set retains order of added activity and ensures uniqueness
+            // therefore obtain the most recently added
+            int size = foregroundActivities.size();
+            String[] activities = foregroundActivities.toArray(new String[size]);
+            return activities[size - 1];
+        }
+    }
+
 }