make MPConfig no longer a Singleton in favor of supporting multiple c…

…onfigs

src/androidTest/java/com/mixpanel/android/mpmetrics/MPConfigTest.java

@@ -12,6 +12,8 @@
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
+import java.util.UUID;
+
 @RunWith(AndroidJUnit4.class)
 public class MPConfigTest {
 
@@ -138,7 +140,19 @@ public void testSetEnableLogging() throws Exception {
         assertFalse(config.DEBUG);
     }
 
-
+    @Test
+    public void testMulptipleConfigs() {
+        String fakeToken = UUID.randomUUID().toString();
+        MixpanelAPI mixpanel1 = MixpanelAPI.getInstance(InstrumentationRegistry.getInstrumentation().getContext(), fakeToken, false);
+        mixpanel1.setServerURL("https://api-eu.mixpanel.com");
+        assertEquals("https://api-eu.mixpanel.com/track/?ip=1", mixpanel1.getEventEndpoint());
+
+        String fakeToken2 = UUID.randomUUID().toString();
+        MixpanelAPI mixpanel2 = MixpanelAPI.getInstance(InstrumentationRegistry.getInstrumentation().getContext(), fakeToken2, false);
+        mixpanel2.setServerURL("https://api.mixpanel.com");
+        assertEquals("https://api.mixpanel.com/track/?ip=1", mixpanel2.getEventEndpoint());
+        assertEquals("https://api-eu.mixpanel.com/track/?ip=1", mixpanel1.getEventEndpoint());
+    }
 
     @Test
     public void testSetFlushBatchSize() {

src/main/java/com/mixpanel/android/mpmetrics/MPConfig.java

@@ -96,16 +96,27 @@ public class MPConfig {
     // Name for persistent storage of app referral SharedPreferences
     /* package */ static final String REFERRER_PREFS_NAME = "com.mixpanel.android.mpmetrics.ReferralInfo";
 
-    // Instances are safe to store, since they're immutable and always the same.
+    /**
+     * Retrieves a new instance of MPConfig with configuration settings loaded from the provided context.
+     * This method creates a new instance each time it is called, allowing for multiple configurations
+     * within the same application.
+     *
+     * Since version 7.4.0, MPConfig is no longer a Singleton, in favor of supporting multiple,
+     * distinct configurations for different Mixpanel instances. This change allows greater flexibility
+     * in scenarios where different parts of an application require different Mixpanel configurations,
+     * such as different endpoints or settings.
+     *
+     * It's important for users of this method to manage the lifecycle of the returned MPConfig instances
+     * themselves. Each call will result in a new configuration instance based on the application's
+     * metadata, and it's the responsibility of the caller to maintain any necessary references to these
+     * instances to use them later in their application.
+     *
+     * @param context The context used to load Mixpanel configuration. It's recommended to provide
+     *                an ApplicationContext to avoid potential memory leaks.
+     * @return A new instance of MPConfig with settings loaded from the context's application metadata.
+     */
     public static MPConfig getInstance(Context context) {
-        synchronized (sInstanceLock) {
-            if (null == sInstance) {
-                final Context appContext = context.getApplicationContext();
-                sInstance = readConfig(appContext);
-            }
-        }
-
-        return sInstance;
+        return readConfig(context.getApplicationContext());
     }
 
     /**
@@ -457,8 +468,5 @@ public String toString() {
     // Mutable, with synchronized accessor and mutator
     private SSLSocketFactory mSSLSocketFactory;
     private OfflineMode mOfflineMode;
-
-    private static MPConfig sInstance;
-    private static final Object sInstanceLock = new Object();
     private static final String LOGTAG = "MixpanelAPI.Conf";
 }