Introduce OfflineManager.runPackDatabaseAutomatically(boolean) API (#78)

* [offline] Introduce OfflineManager.runPackDatabaseAutomatically(boolean) API

* [doc]  update changelog

* [doc] add note to offline region delete API

MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/offline/OfflineManager.java

@@ -310,6 +310,10 @@ public class OfflineManager {
   /**
    * Packs the existing database file into a minimal amount of disk space.
    * <p>
+   * This operation has a performance impact as it will vacuum the database,
+   * forcing it to move pages on the filesystem.
+   * </p>
+   * <p>
    * When the operation is complete or encounters an error, the given callback will be
    * executed on the database thread; it is the responsibility of the SDK bindings
    * to re-execute a user-provided callback on the main thread.
@@ -397,9 +401,9 @@ public class OfflineManager {
   /**
    * Erase resources from the ambient cache, freeing storage space.
    * <p>
-   * Erases the ambient cache, freeing resources. This operation can be
-   * potentially slow because it will trigger a VACUUM on SQLite,
-   * forcing the database to move pages on the filesystem.
+   * Erases the ambient cache, freeing resources.
+   * Note that this operation can be potentially slow if packing the database
+   * occurs automatically ({@link OfflineManager#runPackDatabaseAutomatically(boolean)}).
    * </p>
    * <p>
    * Resources overlapping with offline regions will not be affected
@@ -662,7 +666,7 @@ public class OfflineManager {
    * <p>
    * Once this limit is reached, {@link OfflineRegion.OfflineRegionObserver#mapboxTileCountLimitExceeded(long)}
    * fires every additional attempt to download additional tiles until already downloaded tiles are removed
-   * by calling {@link OfflineRegion#deleteOfflineRegion(OfflineRegion.OfflineRegionDeleteCallback)}.
+   * by calling {@link OfflineRegion#delete(OfflineRegion.OfflineRegionDeleteCallback)}.
    * </p>
    *
    * @param limit the maximum number of tiles allowed to be downloaded
@@ -670,6 +674,25 @@ public class OfflineManager {
   @Keep
   public native void setOfflineMapboxTileCountLimit(long limit);
 
+
+  /**
+   * Sets whether database file packing occurs automatically.
+   * By default, the automatic database file packing is enabled.
+   * <p>
+   * If packing is enabled, database file packing occurs automatically
+   * after an offline region is deleted by calling
+   * {@link OfflineRegion#delete(OfflineRegion.OfflineRegionDeleteCallback)}
+   * or the ambient cache is cleared by calling {@link OfflineManager#clearAmbientCache()}.
+   *
+   * If packing is disabled, disk space will not be freed after
+   * resources are removed unless {@link OfflineManager#packDatabase()} is explicitly called.
+   * </p>
+   *
+   * @param autopack flag setting the automatic database file packing.
+   */
+  @Keep
+  public native void runPackDatabaseAutomatically(boolean autopack);
+
   @Keep
   private native void initialize(FileSource fileSource);
 

MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/offline/OfflineRegion.java

@@ -391,6 +391,8 @@ public class OfflineRegion {
    * When the operation is complete or encounters an error, the given callback will be
    * executed on the main thread.
    * </p>
+   * Note that this operation can be potentially slow if packing the database
+   * occurs automatically ({@link OfflineManager#runPackDatabaseAutomatically(boolean)})
    * <p>
    * After you call this method, you may not call any additional methods on this object.
    * </p>
@@ -401,55 +403,7 @@ public class OfflineRegion {
     if (!isDeleted) {
       isDeleted = true;
       fileSource.activate();
-      deleteOfflineRegion(true /*pack*/, new OfflineRegionDeleteCallback() {
-        @Override
-        public void onDelete() {
-          handler.post(new Runnable() {
-            @Override
-            public void run() {
-              fileSource.deactivate();
-              callback.onDelete();
-              OfflineRegion.this.finalize();
-            }
-          });
-        }
-
-        @Override
-        public void onError(final String error) {
-          handler.post(new Runnable() {
-            @Override
-            public void run() {
-              isDeleted = false;
-              fileSource.deactivate();
-              callback.onError(error);
-            }
-          });
-        }
-      });
-    }
-  }
-
-  /**
-   * Same as {@link OfflineRegion#delete} but skipping database file packing for performance reasons.
-   * <p>
-   * Database file packing can be done later with {@link OfflineManager#packDatabase}.
-   * This method is a useful optimization e.g. when several regions should be deleted in a row.
-   * </p>
-   * <p>
-   * When the operation is complete or encounters an error, the given callback will be
-   * executed on the main thread.
-   * </p>
-   * <p>
-   * After you call this method, you may not call any additional methods on this object.
-   * </p>
-   *
-   * @param callback the callback to be invoked
-   */
-  public void deleteAndSkipPackDatabase(@NonNull final OfflineRegionDeleteCallback callback) {
-    if (!isDeleted) {
-      isDeleted = true;
-      fileSource.activate();
-      deleteOfflineRegion(false /*pack*/, new OfflineRegionDeleteCallback() {
+      deleteOfflineRegion(new OfflineRegionDeleteCallback() {
         @Override
         public void onDelete() {
           handler.post(new Runnable() {
@@ -569,7 +523,7 @@ public class OfflineRegion {
   private native void getOfflineRegionStatus(OfflineRegionStatusCallback callback);
 
   @Keep
-  private native void deleteOfflineRegion(boolean pack, OfflineRegionDeleteCallback callback);
+  private native void deleteOfflineRegion(OfflineRegionDeleteCallback callback);
 
   @Keep
   private native void updateOfflineRegionMetadata(byte[] metadata, OfflineRegionUpdateMetadataCallback callback);