Make import thread-safe to fix #60

Author: ppouchin

src/main/java/fr/igred/omero/GatewayWrapper.java

@@ -42,6 +42,9 @@
 
 import java.util.List;
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 
 /**
@@ -51,6 +54,12 @@
  */
 public abstract class GatewayWrapper {
 
+    /** Number of requested import stores */
+    private final AtomicInteger storeUses = new AtomicInteger(0);
+
+    /** Import store lock */
+    private final Lock storeLock = new ReentrantLock(true);
+
     /** Gateway linking the code to OMERO, only linked to one group. */
     private Gateway gateway;
 
@@ -86,6 +95,35 @@ public Gateway getGateway() {
     }
 
 
+    /**
+     * Retrieves the shared import store in a thread-safe way.
+     *
+     * @throws DSOutOfServiceException If the connection is broken, or not logged in.
+     */
+    private OMEROMetadataStoreClient getImportStoreLocked() throws DSOutOfServiceException {
+        storeLock.lock();
+        try {
+            return gateway.getImportStore(ctx);
+        } finally {
+            storeLock.unlock();
+        }
+    }
+
+
+    /**
+     * Closes the import store in a thread-safe manner.
+     */
+    private void closeImportStoreLocked() {
+        if (storeLock.tryLock()) {
+            try {
+                gateway.closeImport(ctx, null);
+            } finally {
+                storeLock.unlock();
+            }
+        }
+    }
+
+
     /**
      * Returns the current user.
      *
@@ -232,6 +270,8 @@ public void connect(LoginCredentials cred) throws ServiceException {
     public void disconnect() {
         if (isConnected()) {
             boolean sudo = ctx.isSudo();
+            storeUses.set(0);
+            closeImport();
             user = new ExperimenterWrapper(new ExperimenterData());
             ctx = new SecurityContext(-1);
             ctx.setExperimenter(user.asDataObject());
@@ -347,18 +387,30 @@ public AdminFacility getAdminFacility() throws ExecutionException {
     /**
      * Creates or recycles the import store.
      *
-     * @return config.
+     * @return See above.
      *
      * @throws ServiceException Cannot connect to OMERO.
      */
     public OMEROMetadataStoreClient getImportStore() throws ServiceException {
-        return ExceptionHandler.of(gateway, g -> g.getImportStore(ctx))
+        storeUses.incrementAndGet();
+        return ExceptionHandler.of(this, GatewayWrapper::getImportStoreLocked)
                                .rethrow(DSOutOfServiceException.class, ServiceException::new,
                                         "Could not retrieve import store")
                                .get();
     }
 
 
+    /**
+     * Closes the import store.
+     */
+    public void closeImport() {
+        int remainingStores = storeUses.decrementAndGet();
+        if (remainingStores <= 0) {
+            closeImportStoreLocked();
+        }
+    }
+
+
     /**
      * Finds objects on OMERO through a database query.
      *

src/main/java/fr/igred/omero/repository/GenericRepositoryObjectWrapper.java

@@ -107,7 +107,7 @@ protected static boolean importImages(GatewayWrapper client, DataObject target,
             ImportCandidates candidates = new ImportCandidates(reader, paths, handler);
             success = library.importCandidates(config, candidates);
         } finally {
-            store.logout();
+            client.closeImport();
         }
 
         return success;
@@ -163,7 +163,7 @@ protected static List<Long> importImage(GatewayWrapper client, DataObject target
         } catch (Throwable e) {
             throw new OMEROServerError(e);
         } finally {
-            store.logout();
+            client.closeImport();
         }
 
         List<Long> ids = new ArrayList<>(pixels.size());

src/test/java/fr/igred/omero/SudoTest.java

@@ -109,6 +109,8 @@ void sudoImport() throws Exception {
 
         List<ImageWrapper> images = dataset.getImages(client3);
         assertEquals(1, images.size());
+        assertEquals(client3.getId(), images.get(0).getOwner().getId());
+        assertEquals(6L, images.get(0).getGroupId());
 
         client4.delete(images.get(0));
         client4.delete(dataset);