Adding consistent document tree.

Change-Id: I5a70daf3cec7fa83f063bdcb82e1bf38b75419b1

@@ -35,4 +35,30 @@ public class DocumentException extends RuntimeException {
     public DocumentException(Throwable cause) {
         super(cause);
     }
+
+    /**
+     * DocumentTree operation timeout.
+     */
+    public static class Timeout extends DocumentException {
+        public Timeout() {
+        }
+
+        public Timeout(String message) {
+            super(message);
+        }
+
+        public Timeout(String message, Throwable cause) {
+            super(message, cause);
+        }
+
+        public Timeout(Throwable cause) {
+            super(cause);
+        }
+    }
+
+    /**
+     * DocumentTree operation interrupted.
+     */
+    public static class Interrupted extends DocumentException {
+    }
 }

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.store.primitives.resources.impl;
+
+import com.google.common.base.Throwables;
+import org.onosproject.store.service.AsyncDocumentTree;
+import org.onosproject.store.service.ConsistentMapException;
+import org.onosproject.store.service.DocumentException;
+import org.onosproject.store.service.DocumentPath;
+import org.onosproject.store.service.DocumentTree;
+import org.onosproject.store.service.DocumentTreeListener;
+import org.onosproject.store.service.Synchronous;
+import org.onosproject.store.service.Versioned;
+
+import java.util.Map;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+/**
+ * Synchronous wrapper for a {@link AsyncDocumentTree}.  All operations are
+ * made by making the equivalent calls to a backing {@link AsyncDocumentTree}
+ * then blocking until the operations complete or timeout.
+ *
+ * @param <V> the type of the values
+ */
+public class DefaultConsistentDocumentTree<V> extends Synchronous<AsyncDocumentTree<V>> implements DocumentTree<V> {
+
+    private final AsyncDocumentTree<V> backingMap;
+    private static final int MAX_DELAY_BETWEEN_RETRY_MILLS = 50;
+    private final long operationTimeoutMillis;
+
+    public DefaultConsistentDocumentTree(AsyncDocumentTree<V> backingMap,
+                                         long operationTimeoutMillis) {
+        super(backingMap);
+        this.backingMap = backingMap;
+        this.operationTimeoutMillis = operationTimeoutMillis;
+    }
+
+    @Override
+    public DocumentPath root() {
+        return backingMap.root();
+    }
+
+    @Override
+    public Map<String, Versioned<V>> getChildren(DocumentPath path) {
+        return complete(backingMap.getChildren(path));
+    }
+
+    @Override
+    public Versioned<V> get(DocumentPath path) {
+        return complete(backingMap.get(path));
+    }
+
+    @Override
+    public Versioned<V> set(DocumentPath path, V value) {
+        return complete(backingMap.set(path, value));
+    }
+
+    @Override
+    public boolean create(DocumentPath path, V value) {
+        return complete(backingMap.create(path, value));
+    }
+
+    @Override
+    public boolean createRecursive(DocumentPath path, V value) {
+        return complete(backingMap.createRecursive(path, value));
+    }
+
+    @Override
+    public boolean replace(DocumentPath path, V newValue, long version) {
+        return complete(backingMap.replace(path, newValue, version));
+    }
+
+    @Override
+    public boolean replace(DocumentPath path, V newValue, V currentValue) {
+        return complete(backingMap.replace(path, newValue, currentValue));
+    }
+
+    @Override
+    public Versioned<V> removeNode(DocumentPath path) {
+        return complete(backingMap.removeNode(path));
+    }
+
+    @Override
+    public void addListener(DocumentPath path, DocumentTreeListener<V> listener) {
+        complete(backingMap.addListener(path, listener));
+    }
+
+    @Override
+    public void removeListener(DocumentTreeListener<V> listener) {
+        complete(backingMap.removeListener(listener));
+    }
+
+    @Override
+    public void addListener(DocumentTreeListener<V> listener) {
+        complete(backingMap.addListener(listener));
+    }
+
+    private <T> T complete(CompletableFuture<T> future) {
+        try {
+            return future.get(operationTimeoutMillis, TimeUnit.MILLISECONDS);
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            throw new DocumentException.Interrupted();
+        } catch (TimeoutException e) {
+            throw new DocumentException.Timeout(name());
+        } catch (ExecutionException e) {
+            Throwables.propagateIfPossible(e.getCause());
+            throw new ConsistentMapException(e.getCause());
+        }
+    }
+}