Publish SnapshotBacked transactions

[controller.git] / opendaylight / md-sal / sal-dom-spi / src / main / java / org / opendaylight / controller / sal / core / spi / data / SnapshotBackedReadTransaction.java

diff --git a/opendaylight/md-sal/sal-dom-spi/src/main/java/org/opendaylight/controller/sal/core/spi/data/SnapshotBackedReadTransaction.java b/opendaylight/md-sal/sal-dom-spi/src/main/java/org/opendaylight/controller/sal/core/spi/data/SnapshotBackedReadTransaction.java
new file mode 100644 (file)
index 0000000..8e5957c
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+++ b/opendaylight/md-sal/sal-dom-spi/src/main/java/org/opendaylight/controller/sal/core/spi/data/SnapshotBackedReadTransaction.java
@@ -0,0 +1,85 @@
+/*
+ * 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.controller.sal.core.spi.data;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import com.google.common.annotations.Beta;
+import com.google.common.base.Optional;
+import com.google.common.base.Preconditions;
+import com.google.common.util.concurrent.CheckedFuture;
+import com.google.common.util.concurrent.Futures;
+import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
+import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
+import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeSnapshot;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ *
+ * Implementation of read-only transaction backed by {@link DataTreeSnapshot}
+ *
+ * Implementation of read-only transaction backed by {@link DataTreeSnapshot}
+ * which delegates most of its calls to similar methods provided by underlying snapshot.
+ *
+ * <T> identifier type
+ */
+@Beta
+public final class SnapshotBackedReadTransaction<T> extends AbstractDOMStoreTransaction<T> implements DOMStoreReadTransaction {
+    private static final Logger LOG = LoggerFactory.getLogger(SnapshotBackedReadTransaction.class);
+    private volatile DataTreeSnapshot stableSnapshot;
+
+    /**
+     * Creates a new read-only transaction.
+     *
+     * @param identifier Transaction Identifier
+     * @param debug Enable transaction debugging
+     * @param snapshot Snapshot which will be modified.
+     */
+    SnapshotBackedReadTransaction(final T identifier, final boolean debug, final DataTreeSnapshot snapshot) {
+        super(identifier, debug);
+        this.stableSnapshot = Preconditions.checkNotNull(snapshot);
+        LOG.debug("ReadOnly Tx: {} allocated with snapshot {}", identifier, snapshot);
+    }
+
+    @Override
+    public void close() {
+        LOG.debug("Store transaction: {} : Closed", getIdentifier());
+        stableSnapshot = null;
+    }
+
+    @Override
+    public CheckedFuture<Optional<NormalizedNode<?,?>>, ReadFailedException> read(final YangInstanceIdentifier path) {
+        LOG.debug("Tx: {} Read: {}", getIdentifier(), path);
+        checkNotNull(path, "Path must not be null.");
+
+        final DataTreeSnapshot snapshot = stableSnapshot;
+        if (snapshot == null) {
+            return Futures.immediateFailedCheckedFuture(new ReadFailedException("Transaction is closed"));
+        }
+
+        try {
+            return Futures.immediateCheckedFuture(snapshot.readNode(path));
+        } catch (Exception e) {
+            LOG.error("Tx: {} Failed Read of {}", getIdentifier(), path, e);
+            return Futures.immediateFailedCheckedFuture(new ReadFailedException("Read failed",e));
+        }
+    }
+
+    @Override
+    public CheckedFuture<Boolean, ReadFailedException> exists(final YangInstanceIdentifier path) {
+        LOG.debug("Tx: {} Exists: {}", getIdentifier(), path);
+        checkNotNull(path, "Path must not be null.");
+
+        try {
+            return Futures.immediateCheckedFuture(read(path).checkedGet().isPresent());
+        } catch (ReadFailedException e) {
+            return Futures.immediateFailedCheckedFuture(e);
+        }
+    }
+}