Do not allow multi-datastore transactions

[mdsal.git] / dom / mdsal-dom-broker / src / main / java / org / opendaylight / mdsal / dom / broker / AbstractDOMForwardedTransaction.java

diff --git a/dom/mdsal-dom-broker/src/main/java/org/opendaylight/mdsal/dom/broker/AbstractDOMForwardedTransaction.java b/dom/mdsal-dom-broker/src/main/java/org/opendaylight/mdsal/dom/broker/AbstractDOMForwardedTransaction.java
new file mode 100644 (file)
index 0000000..2d47e79
--- /dev/null
+++ b/dom/mdsal-dom-broker/src/main/java/org/opendaylight/mdsal/dom/broker/AbstractDOMForwardedTransaction.java
@@ -0,0 +1,131 @@
+/*
+ * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.mdsal.dom.broker;
+
+import static java.util.Objects.requireNonNull;
+
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.VarHandle;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.function.Function;
+import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.Nullable;
+import org.opendaylight.mdsal.common.api.LogicalDatastoreType;
+import org.opendaylight.mdsal.common.api.TransactionDatastoreMismatchException;
+import org.opendaylight.mdsal.dom.api.DOMDataTreeTransaction;
+import org.opendaylight.mdsal.dom.spi.store.DOMStoreTransaction;
+
+/**
+ * Composite DOM Transaction backed by {@link DOMStoreTransaction}.
+ *
+ * <p>
+ * Abstract base for composite transaction, which provides access only to common
+ * functionality as retrieval of subtransaction, close method and retrieval of
+ * identifier.
+ *
+ * @param <T> Subtransaction type
+ */
+abstract class AbstractDOMForwardedTransaction<T extends DOMStoreTransaction>
+        implements DOMDataTreeTransaction {
+    private static final VarHandle BACKING_TX;
+
+    static {
+        try {
+            BACKING_TX = MethodHandles.lookup().findVarHandle(AbstractDOMForwardedTransaction.class,
+                "backingTx", Entry.class);
+        } catch (NoSuchFieldException | IllegalAccessException e) {
+            throw new ExceptionInInitializerError(e);
+        }
+    }
+
+    private final @NonNull Object identifier;
+    private final Function<LogicalDatastoreType, T> backingTxFactory;
+
+    private volatile Entry<LogicalDatastoreType, T> backingTx;
+
+    /**
+     * Creates new composite Transactions.
+     *
+     * @param identifier
+     *            Identifier of transaction.
+     * @param backingTxFactory
+     *            Function which supplies transaction depending on store type
+     */
+    protected AbstractDOMForwardedTransaction(final Object identifier,
+            final Function<LogicalDatastoreType, T> backingTxFactory) {
+        this.identifier = requireNonNull(identifier, "Identifier should not be null");
+        this.backingTxFactory = requireNonNull(backingTxFactory, "Backing transaction factory should not be null");
+    }
+
+    /**
+     * Returns subtransaction associated with supplied datastore type.
+     *
+     * <p>
+     * The method allows usage of single datastore type per transaction instance;
+     * eligible datastore type is defined by first method access.
+     *
+     * @param datastoreType is used to identify subtransaction object
+     * @return the subtransaction object
+     * @throws NullPointerException if datastoreType is {@code null}
+     * @throws IllegalArgumentException if datastoreType is not supported
+     * @throws TransactionDatastoreMismatchException if datastoreType mismatches the one used at first access
+     */
+    protected final @NonNull T getSubtransaction(final LogicalDatastoreType datastoreType) {
+        final var ds = requireNonNull(datastoreType, "datastoreType must not be null.");
+
+        var entry = backingTx;
+        if (entry == null) {
+            final var tx = backingTxFactory.apply(datastoreType);
+            final var newEntry = Map.entry(ds, tx);
+            final var witness = (Entry<LogicalDatastoreType, T>) BACKING_TX.compareAndExchange(this, null, newEntry);
+            if (witness != null) {
+                tx.close();
+                entry = witness;
+            } else {
+                entry = newEntry;
+            }
+        }
+
+        final var encountered = entry.getKey();
+        if (encountered != ds) {
+            throw new TransactionDatastoreMismatchException(encountered, ds);
+        }
+        return entry.getValue();
+    }
+
+    /**
+     * Returns immutable Iterable of all subtransactions.
+     */
+    protected @Nullable T getSubtransaction() {
+        final Entry<LogicalDatastoreType, T> entry;
+        return (entry = backingTx) == null ? null : entry.getValue();
+    }
+
+    @Override
+    public Object getIdentifier() {
+        return identifier;
+    }
+
+    @SuppressWarnings("checkstyle:IllegalCatch")
+    protected void closeSubtransactions() {
+        /*
+         * We share one exception for all failures, which are added
+         * as supressedExceptions to it.
+         */
+        final var subtransaction = getSubtransaction();
+        if (subtransaction != null) {
+            try {
+                subtransaction.close();
+            } catch (Exception e) {
+                // If we did not allocate failure we allocate it
+                throw new IllegalStateException("Uncaught exception occurred during closing transaction", e);
+            }
+        }
+    }
+}