BoxStore: keep reference to not-closed SyncClient.

Author: greenrobot-team

objectbox-java/src/main/java/io/objectbox/BoxStore.java

@@ -53,6 +53,7 @@
 import io.objectbox.reactive.DataObserver;
 import io.objectbox.reactive.DataPublisher;
 import io.objectbox.reactive.SubscriptionBuilder;
+import io.objectbox.sync.SyncClient;
 
 /**
  * Represents an ObjectBox database and gives you {@link Box}es to get and put Objects of a specific type
@@ -244,6 +245,12 @@ public static boolean isSyncServerAvailable() {
 
     private final TxCallback<?> failedReadTxAttemptCallback;
 
+    /**
+     * Keeps a reference so the library user does not have to.
+     */
+    @Nullable
+    private SyncClient syncClient;
+
     BoxStore(BoxStoreBuilder builder) {
         context = builder.context;
         relinker = builder.relinker;
@@ -1163,4 +1170,15 @@ public long getNativeStore() {
         return handle;
     }
 
+    /**
+     * Returns the {@link SyncClient} associated with this store. To create one see {@link io.objectbox.sync.Sync Sync}.
+     */
+    @Nullable
+    public SyncClient getSyncClient() {
+        return syncClient;
+    }
+
+    public void setSyncClient(@Nullable SyncClient syncClient) {
+        this.syncClient = syncClient;
+    }
 }

objectbox-java/src/main/java/io/objectbox/sync/SyncBuilder.java

@@ -141,6 +141,9 @@ public SyncClient build() {
         if (credentials == null) {
             throw new IllegalStateException("Credentials are required.");
         }
+        if (boxStore.getSyncClient() != null) {
+            throw new IllegalStateException("The given store is already associated with a Sync client, close it first.");
+        }
         return new SyncClientImpl(this);
     }
 

objectbox-java/src/main/java/io/objectbox/sync/SyncClientImpl.java

@@ -1,5 +1,6 @@
 package io.objectbox.sync;
 
+import io.objectbox.BoxStore;
 import io.objectbox.InternalAccess;
 import io.objectbox.annotation.apihint.Experimental;
 import io.objectbox.annotation.apihint.Internal;
@@ -16,6 +17,8 @@
 @Internal
 public class SyncClientImpl implements SyncClient {
 
+    @Nullable
+    private BoxStore boxStore;
     private final String serverUrl;
     private final InternalListener internalListener;
     @Nullable
@@ -28,6 +31,7 @@ public class SyncClientImpl implements SyncClient {
     private volatile boolean started;
 
     SyncClientImpl(SyncBuilder builder) {
+        this.boxStore = builder.boxStore;
         this.serverUrl = builder.url;
         this.connectivityMonitor = builder.platform.getConnectivityMonitor();
 
@@ -58,6 +62,9 @@ public class SyncClientImpl implements SyncClient {
 
         setLoginCredentials(builder.credentials);
 
+        // If created successfully, let store keep a reference so the caller does not have to.
+        builder.boxStore.setSyncClient(this);
+
         if (!builder.manualStart) {
             start();
         }
@@ -151,12 +158,22 @@ public synchronized void stop() {
 
     @Override
     public void close() {
-        if (connectivityMonitor != null) {
-            connectivityMonitor.removeObserver();
-        }
-
         long handleToDelete;
         synchronized (this) {
+            if (connectivityMonitor != null) {
+                connectivityMonitor.removeObserver();
+            }
+
+            // Remove instance reference from store, release store reference.
+            BoxStore boxStore = this.boxStore;
+            if (boxStore != null) {
+                SyncClient syncClient = boxStore.getSyncClient();
+                if (syncClient == this) {
+                    boxStore.setSyncClient(null);
+                }
+                this.boxStore = null;
+            }
+
             handleToDelete = this.handle;
             handle = 0;
         }