[libaryloader] synchronise access to the library loader load method (#58)

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 Mapbox welcomes participation and contributions from everyone.  If you'd like to do so please see the [`Contributing Guide`](https://github.com/mapbox/mapbox-gl-native/blob/master/CONTRIBUTING.md) first to get started.
 
+## Master
+### Bugs
+ - Synchronise LibaryLoader#loadLibrary to avoid race conditions resulting in UnsatisfiedLinkError [#58](https://github.com/mapbox/mapbox-gl-native-android/pull/58)
+
 ## 8.6.0-alpha.1 - November 14, 2019
 [Changes](https://github.com/mapbox/mapbox-gl-native-android/compare/android-v8.5.0...android-v8.6.0-alpha.1) since [Mapbox Maps SDK for Android v8.5.0](https://github.com/mapbox/mapbox-gl-native-android/releases/tag/android-v8.5.0):
 ### Features

MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/LibraryLoader.java

@@ -5,7 +5,7 @@ import com.mapbox.mapboxsdk.log.Logger;
 /**
  * Loads the mapbox-gl shared library
  * <p>
- * By default uses the {@link System#loadLibrary(String)},
+ * By default uses SoLoader from https://github.com/facebook/SoLoader
  * use {@link #setLibraryLoader(LibraryLoader)} to provide an alternative library loading hook.
  * </p>
  */
@@ -36,7 +36,7 @@ public abstract class LibraryLoader {
    * Catches UnsatisfiedLinkErrors and prints a warning to logcat.
    * </p>
    */
-  public static void load() {
+  public static synchronized void load() {
     try {
       if (!loaded) {
         loaded = true;

MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/module/loader/LibraryLoaderProviderImpl.java

@@ -12,7 +12,7 @@ import static com.facebook.soloader.SoLoader.loadLibrary;
 /**
  * Concrete implementation of a native library loader.
  * <p>
- * Uses ReLinker from https://github.com/KeepSafe/ReLinker.
+ * Uses SoLoader from https://github.com/facebook/SoLoader.
  * </p>
  */
 public class LibraryLoaderProviderImpl implements LibraryLoaderProvider {
@@ -28,7 +28,7 @@ public class LibraryLoaderProviderImpl implements LibraryLoaderProvider {
   }
 
   /**
-   * Concrete implementation of a LibraryLoader using ReLinker.
+   * Concrete implementation of a LibraryLoader using SoLoader.
    */
   private static class SoLibraryLoader extends LibraryLoader {
 
@@ -43,6 +43,7 @@ public class LibraryLoaderProviderImpl implements LibraryLoaderProvider {
       } catch (MapboxConfigurationException exception) {
         Logger.e(TAG, "Couldn't load so file with relinker, application context missing, "
           + "call Mapbox.getInstance(Context context, String accessToken) first");
+        throw new UnsatisfiedLinkError(exception.getMessage());
       }
     }
   }