Add setter for session rotation time (#544)

* split constant into value and units

* add setter for sessionIdRotationTime

* add experimental annotation to setSessionIdRotationTime and fix checkstyle issues

Author: zugaldia

mapbox/libandroid-telemetry/src/main/java/com/mapbox/services/android/telemetry/MapboxTelemetry.java

@@ -13,6 +13,7 @@
 import android.os.BatteryManager;
 import android.os.Build;
 import android.os.Handler;
+import android.support.annotation.IntRange;
 import android.support.annotation.NonNull;
 import android.support.v4.content.LocalBroadcastManager;
 import android.text.TextUtils;
@@ -72,6 +73,7 @@ public class MapboxTelemetry implements Callback, LocationEngineListener {
   private Boolean telemetryEnabled = null;
   protected CopyOnWriteArrayList<TelemetryListener> telemetryListeners;
   private Hashtable<String, Object> customTurnstileEvent = null;
+  private int sessionIdRotationTime = TelemetryConstants.DEFAULT_SESSION_ID_ROTATION_HOURS;
 
   /**
    * Private constructor for configuring the single instance per app.
@@ -157,6 +159,14 @@ public void setCustomTurnstileEvent(Hashtable<String, Object> customTurnstileEve
     this.customTurnstileEvent = customTurnstileEvent;
   }
 
+  // For internal use only
+  // This is an experimental API. Experimental APIs are quickly evolving and
+  // might change or be removed in minor versions.
+  @Experimental
+  public void setSessionIdRotationTime(@IntRange(from = 1, to = 24) int sessionIdRotationTime) {
+    this.sessionIdRotationTime = sessionIdRotationTime; // in hours
+  }
+
   /**
    * Checks that TelemetryService has been configured by developer
    */
@@ -219,7 +229,7 @@ private void checkStagingServerInformation() {
         // Set new client information (if needed)
         if (!TextUtils.isEmpty(stagingURL) && !TextUtils.isEmpty(stagingAccessToken)) {
           Log.w(LOG_TAG, String.format("Using staging server '%s' with access token '%s'.",
-              stagingURL, stagingAccessToken));
+            stagingURL, stagingAccessToken));
           client.setEventsEndpoint(stagingURL);
           client.setAccessToken(stagingAccessToken);
           client.setStagingEnvironment(true);
@@ -234,7 +244,7 @@ private void setUserAgent() {
     // Append app identifier to user agent if present
     String appIdentifier = TelemetryUtils.getApplicationIdentifier(context);
     String fullUserAgent = TextUtils.isEmpty(appIdentifier) ? userAgent : Util.toHumanReadableAscii(
-        String.format(TelemetryConstants.DEFAULT_LOCALE, "%s %s", appIdentifier, userAgent));
+      String.format(TelemetryConstants.DEFAULT_LOCALE, "%s %s", appIdentifier, userAgent));
     client.setUserAgent(fullUserAgent);
   }
 
@@ -244,7 +254,7 @@ private void setUserAgent() {
   private void rotateSessionId() {
     long timeSinceLastSet = System.currentTimeMillis() - mapboxSessionIdLastSet;
     if ((TextUtils.isEmpty(mapboxSessionId))
-      || (timeSinceLastSet > TelemetryConstants.SESSION_ID_ROTATION_MS)) {
+      || (timeSinceLastSet > sessionIdRotationTime * TelemetryConstants.ONE_HOUR_IN_MS)) {
       mapboxSessionId = TelemetryUtils.buildUUID();
       mapboxSessionIdLastSet = System.currentTimeMillis();
     }
@@ -660,7 +670,7 @@ private void shutdownTelemetry() {
     context.stopService(new Intent(context, TelemetryService.class));
     if (locationEngine == null) {
       Log.e(LOG_TAG, String.format(
-          "Shutdown error: Location Engine instance wasn't set up (initialized: %b).", initialized));
+        "Shutdown error: Location Engine instance wasn't set up (initialized: %b).", initialized));
     } else {
       locationEngine.removeLocationEngineListener(this);
       locationEngine.removeLocationUpdates();

mapbox/libandroid-telemetry/src/main/java/com/mapbox/services/android/telemetry/constants/TelemetryConstants.java

@@ -20,7 +20,8 @@ public class TelemetryConstants {
   public static final long FLUSH_PERIOD_MS = 3 * 60 * 1_000; // 3 minutes
   public static final int FLUSH_EVENTS_CAP = 180; // 180 seconds or 180 events
 
-  public static final int SESSION_ID_ROTATION_MS = 24 * 60 * 60 * 1_000; // 24 hours
+  public static final int ONE_HOUR_IN_MS = 60 * 60 * 1_000;
+  public static final int DEFAULT_SESSION_ID_ROTATION_HOURS = 24;
 
   /**
    * Key used to store CN endpoint settings in AndroidManifest.xml