samza-kv-couchbase/src/main/java/org/apache/samza/table/remote/couchbase/CouchbaseTableWriteFunction.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.samza.table.remote.couchbase;

import com.couchbase.client.deps.io.netty.buffer.Unpooled;
import com.couchbase.client.java.document.BinaryDocument;
import com.couchbase.client.java.document.Document;
import com.couchbase.client.java.document.JsonDocument;
import com.couchbase.client.java.document.json.JsonObject;

import com.google.common.base.Preconditions;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.TimeUnit;

import org.apache.commons.lang3.StringUtils;
import org.apache.samza.SamzaException;
import org.apache.samza.context.Context;
import org.apache.samza.table.AsyncReadWriteTable;
import org.apache.samza.table.remote.TableWriteFunction;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import rx.Observable;
import rx.SingleSubscriber;

/**
 * TableWriteFunction implementation for writing to Couchbase. The value type can be either {@link JsonObject} or
 * any other Object. If the value type is JsonObject, data will be stored in Couchbase in JSON format, which can be
 * queried with N1QL. Otherwise, a {@link org.apache.samza.serializers.Serde} needs to be provided to serialize and
 * deserialize the value object.
 * @param <V> Type of values to write to Couchbase
 */
public class CouchbaseTableWriteFunction<V> extends BaseCouchbaseTableFunction<V>
    implements TableWriteFunction<String, V> {

  private static final Logger LOGGER = LoggerFactory.getLogger(CouchbaseTableWriteFunction.class);

  /**
   * Construct an instance of {@link CouchbaseTableWriteFunction}.
   * @param bucketName Name of the couchbase bucket
   * @param clusterNodes Some Hosts of the Couchbase cluster. Recommended to provide more than one nodes so that if
   *                     the first node could not be connected, other nodes can be tried.
   * @param valueClass Type of values
   */
  public CouchbaseTableWriteFunction(String bucketName, Class<V> valueClass, String... clusterNodes) {
    super(bucketName, valueClass, clusterNodes);
  }

  @Override
  public void init(Context context, AsyncReadWriteTable table) {
    super.init(context, table);
    LOGGER.info("Write function for bucket {} initialized successfully", bucketName);
  }

  @Override
  public CompletableFuture<Void> putAsync(String key, V record) {
    Preconditions.checkArgument(StringUtils.isNotBlank(key), "key must not be null, empty or blank");
    Preconditions.checkArgument(!key.contains(" "), String.format("key should not contain spaces: %s", key));
    Preconditions.checkNotNull(record);
    Document<?> document = record instanceof JsonObject
        ? JsonDocument.create(key, (int) ttl.getSeconds(), (JsonObject) record)
        : BinaryDocument.create(key, (int) ttl.getSeconds(), Unpooled.copiedBuffer(valueSerde.toBytes(record)));
    return asyncWriteHelper(
        bucket.async().upsert(document, timeout.toMillis(), TimeUnit.MILLISECONDS),
        String.format("Failed to insert key %s into bucket %s", key, bucketName));
  }

  @Override
  public CompletableFuture<Void> deleteAsync(String key) {
    Preconditions.checkArgument(StringUtils.isNotBlank(key), "key must not be null, empty or blank");
    return asyncWriteHelper(
        bucket.async().remove(key, timeout.toMillis(), TimeUnit.MILLISECONDS),
        String.format("Failed to delete key %s from bucket %s.", key, bucketName));
  }

  /*
   * Helper method for putAsync and deleteAsync to convert Single to CompletableFuture.
   */
  protected CompletableFuture<Void>  asyncWriteHelper(Observable<? extends Document> observable, String errorMessage) {
    return asyncWriteHelper(observable, errorMessage, true);
  }

  protected <T> CompletableFuture<T>  asyncWriteHelper(Observable<? extends Document> observable, String errorMessage,
      boolean isVoid) {
    CompletableFuture<T> future = new CompletableFuture<>();
    observable.toSingle().subscribe(new SingleSubscriber<Document>() {
      @Override
      public void onSuccess(Document document) {
        if (isVoid) {
          future.complete(null);
        } else {
          future.complete((T) document.content());
        }
      }

      @Override
      public void onError(Throwable error) {
        future.completeExceptionally(new SamzaException(errorMessage, error));
      }
    });
    return future;
  }

}