HONEYCOMB-61: Config persister

Add PersistingDataTree adapter for in memory config data tree
Using JSON NormalizedNode writers from ODL

Change-Id: Ida91fe6aa34aaeaedcd061ba1551afe49bbddbbb
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>

2 files changed, 185 insertions, 1 deletions

diff --git a/v3po/data-impl/src/main/java/io/fd/honeycomb/v3po/data/impl/ConfigDataTree.java b/v3po/data-impl/src/main/java/io/fd/honeycomb/v3po/data/impl/ConfigDataTree.java
index ab4cf6446..1e118ff2a 100644
--- a/v3po/data-impl/src/main/java/io/fd/honeycomb/v3po/data/impl/ConfigDataTree.java
+++ b/v3po/data-impl/src/main/java/io/fd/honeycomb/v3po/data/impl/ConfigDataTree.java
@@ -109,7 +109,6 @@ public final class ConfigDataTree implements ModifiableDataTree {
         final Map<InstanceIdentifier<?>, DataObject> nodesAfter = extractNetconfData(normalizedDataAfter);
         LOG.debug("ConfigDataTree.modify() extracted nodesAfter={}", nodesAfter.keySet());
 
-
         final DOMDataReadOnlyTransaction beforeTx = new ReadOnlyTransaction(EMPTY_OPERATIONAL, takeSnapshot());
         final ConfigSnapshot modificationSnapshot = new ConfigSnapshot(modification);
         final DOMDataReadOnlyTransaction afterTx = new ReadOnlyTransaction(EMPTY_OPERATIONAL, modificationSnapshot);
diff --git a/v3po/data-impl/src/main/java/io/fd/honeycomb/v3po/data/impl/PersistingDataTreeAdapter.java b/v3po/data-impl/src/main/java/io/fd/honeycomb/v3po/data/impl/PersistingDataTreeAdapter.java
new file mode 100644
index 000000000..25d1d8dda
--- /dev/null
+++ b/v3po/data-impl/src/main/java/io/fd/honeycomb/v3po/data/impl/PersistingDataTreeAdapter.java
@@ -0,0 +1,185 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.v3po.data.impl;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.base.Charsets;
+import com.google.common.base.Optional;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import javax.annotation.Nonnull;
+import org.opendaylight.controller.sal.core.api.model.SchemaService;
+import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
+import org.opendaylight.yangtools.yang.data.api.schema.ContainerNode;
+import org.opendaylight.yangtools.yang.data.api.schema.DataContainerChild;
+import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
+import org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeStreamWriter;
+import org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeModification;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeSnapshot;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
+import org.opendaylight.yangtools.yang.data.codec.gson.JSONCodecFactory;
+import org.opendaylight.yangtools.yang.data.codec.gson.JSONNormalizedNodeStreamWriter;
+import org.opendaylight.yangtools.yang.data.codec.gson.JsonWriterFactory;
+import org.opendaylight.yangtools.yang.model.api.SchemaContext;
+import org.opendaylight.yangtools.yang.model.api.SchemaPath;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Adapter for a DataTree that stores current state of data in backing DataTree on each successful commit.
+ * Uses JSON format.
+ */
+public class PersistingDataTreeAdapter implements org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree, AutoCloseable {
+
+    private static final Logger LOG = LoggerFactory.getLogger(PersistingDataTreeAdapter.class);
+
+    private final DataTree delegateDependency;
+    private SchemaService schemaServiceDependency;
+    private final Path path;
+
+    /**
+     * Create new Persisting DataTree adapter
+     *
+     * @param delegateDependency backing data tree that actually handles all the operations
+     * @param persistPath path to a file (existing or not) to be used as storage for persistence. Full control over
+     *                    a file at peristPath is expected
+     * @param schemaServiceDependency schemaContext provier
+     */
+    public PersistingDataTreeAdapter(@Nonnull final DataTree delegateDependency,
+                                     @Nonnull final SchemaService schemaServiceDependency,
+                                     @Nonnull final Path persistPath) {
+        this.path = testPersistPath(persistPath);
+        this.delegateDependency = delegateDependency;
+        this.schemaServiceDependency = schemaServiceDependency;
+    }
+
+    /**
+     * Test whether file at persistPath is a file and can be created/deleted
+     */
+    private Path testPersistPath(final Path persistPath) {
+        try {
+            checkArgument(!Files.isDirectory(persistPath), "Path %s points to a directory", persistPath);
+            Files.createDirectories(persistPath.getParent());
+            Files.write(persistPath, new byte[]{}, StandardOpenOption.CREATE);
+        } catch (IOException | UnsupportedOperationException e) {
+            LOG.warn("Provided path for persistence: {} is not usable", persistPath, e);
+            throw new IllegalArgumentException("Path " + persistPath + " cannot be used as ");
+        } finally {
+            try {
+                Files.delete(persistPath);
+            } catch (IOException e) {
+                LOG.warn("Unable to delete file at {}", persistPath, e);
+            }
+        }
+
+        return persistPath;
+    }
+
+    @Override
+    public DataTreeSnapshot takeSnapshot() {
+        return delegateDependency.takeSnapshot();
+    }
+
+    @Override
+    public void setSchemaContext(final SchemaContext schemaContext) {
+        delegateDependency.setSchemaContext(schemaContext);
+    }
+
+    @Override
+    public void commit(final DataTreeCandidate dataTreeCandidate) {
+        LOG.trace("Commit detected");
+        delegateDependency.commit(dataTreeCandidate);
+        LOG.debug("Delegate commit successful. Persisting data");
+
+        // FIXME doing full read and full write might not be the fastest way of persisting data here
+        final DataTreeSnapshot dataTreeSnapshot = delegateDependency.takeSnapshot();
+
+        // TODO this can be handled in background by a dedicated thread + a limited blocking queue
+        // TODO enable configurable granularity for persists. Maybe doing write on every modification is too much
+        // and we could do bulk persist
+        persistCurrentData(dataTreeSnapshot.readNode(YangInstanceIdentifier.EMPTY));
+    }
+
+    private void persistCurrentData(final Optional<NormalizedNode<?, ?>> currentRoot) {
+        if(currentRoot.isPresent()) {
+            try {
+                LOG.trace("Persisting current data: {} into: {}", currentRoot.get(), path);
+                // TODO once we are in static environment, do the writer, streamWriter and NNWriter initialization only once
+                final JsonWriter
+                    jsonWriter = createJsonWriter(Files.newOutputStream(path, StandardOpenOption.CREATE), true);
+                final NormalizedNodeStreamWriter streamWriter = JSONNormalizedNodeStreamWriter
+                    .createNestedWriter(JSONCodecFactory.create(schemaServiceDependency.getGlobalContext()), SchemaPath.ROOT, null, jsonWriter);
+                final NormalizedNodeWriter normalizedNodeWriter =
+                    NormalizedNodeWriter.forStreamWriter(streamWriter, true);
+                jsonWriter.beginObject();
+                writeChildren(normalizedNodeWriter,(ContainerNode) currentRoot.get());
+                jsonWriter.endObject();
+                jsonWriter.flush();
+                LOG.trace("Data persisted successfully in {}", path);
+            } catch (IOException e) {
+                throw new IllegalStateException("Unable to persist current data", e);
+            }
+        } else {
+            LOG.debug("Skipping persistence, since there's no data to persist");
+        }
+    }
+
+    private void writeChildren(final NormalizedNodeWriter nnWriter, final ContainerNode data) throws IOException {
+        for(final DataContainerChild<? extends YangInstanceIdentifier.PathArgument, ?> child : data.getValue()) {
+            nnWriter.write(child);
+        }
+    }
+
+    private JsonWriter createJsonWriter(final OutputStream entityStream, boolean prettyPrint) {
+        if (prettyPrint) {
+            return JsonWriterFactory.createJsonWriter(new OutputStreamWriter(entityStream, Charsets.UTF_8), 2);
+        } else {
+            return JsonWriterFactory.createJsonWriter(new OutputStreamWriter(entityStream, Charsets.UTF_8));
+        }
+    }
+
+    @Override
+    public YangInstanceIdentifier getRootPath() {
+        return delegateDependency.getRootPath();
+    }
+
+    @Override
+    public void validate(final DataTreeModification dataTreeModification) throws DataValidationFailedException {
+        delegateDependency.validate(dataTreeModification);
+    }
+
+    @Override
+    public DataTreeCandidate prepare(
+        final DataTreeModification dataTreeModification) {
+        return delegateDependency.prepare(dataTreeModification);
+    }
+
+    @Override
+    public void close() throws Exception {
+        LOG.trace("Closing {} for {}", getClass().getSimpleName(), path);
+        // NOOP
+    }
+}