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From zentol <...@git.apache.org>
Subject [GitHub] flink pull request: [FLINK-3311/FLINK-3332] Add Cassandra connecto...
Date Wed, 18 May 2016 10:15:24 GMT
Github user zentol commented on a diff in the pull request:

    https://github.com/apache/flink/pull/1771#discussion_r63678205
  
    --- Diff: flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/GenericAtLeastOnceSink.java
---
    @@ -0,0 +1,192 @@
    +/**
    + * 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
    + * <p/>
    + * http://www.apache.org/licenses/LICENSE-2.0
    + * <p/>
    + * 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.flink.streaming.runtime.operators;
    +
    +import org.apache.flink.api.common.typeutils.TypeSerializer;
    +import org.apache.flink.api.java.tuple.Tuple2;
    +import org.apache.flink.core.memory.DataInputView;
    +import org.apache.flink.runtime.io.disk.InputViewIterator;
    +import org.apache.flink.runtime.state.AbstractStateBackend;
    +import org.apache.flink.runtime.state.StateHandle;
    +import org.apache.flink.runtime.util.ReusingMutableToRegularIteratorWrapper;
    +import org.apache.flink.streaming.api.operators.AbstractStreamOperator;
    +import org.apache.flink.streaming.api.operators.OneInputStreamOperator;
    +import org.apache.flink.streaming.api.watermark.Watermark;
    +import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
    +import org.apache.flink.streaming.runtime.tasks.StreamTaskState;
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
    +
    +import java.io.IOException;
    +import java.io.Serializable;
    +import java.util.HashSet;
    +import java.util.Set;
    +import java.util.TreeMap;
    +import java.util.UUID;
    +
    +/**
    + * Generic Sink that emits its input elements into an arbitrary backend. This sink is
integrated with the checkpointing
    + * mechanism and can provide exactly-once guarantees; depending on the storage backend
and sink/committer implementation.
    + * <p/>
    + * Incoming records are stored within a {@link org.apache.flink.runtime.state.AbstractStateBackend},
and only committed if a
    + * checkpoint is completed.
    + *
    + * @param <IN> Type of the elements emitted by this sink
    + */
    +public abstract class GenericAtLeastOnceSink<IN> extends AbstractStreamOperator<IN>
implements OneInputStreamOperator<IN, IN> {
    +	protected static final Logger LOG = LoggerFactory.getLogger(GenericAtLeastOnceSink.class);
    +	private final CheckpointCommitter committer;
    +	private transient AbstractStateBackend.CheckpointStateOutputView out;
    +	protected final TypeSerializer<IN> serializer;
    +	private final String id;
    +
    +	private ExactlyOnceState state = new ExactlyOnceState();
    +
    +	public GenericAtLeastOnceSink(CheckpointCommitter committer, TypeSerializer<IN>
serializer, String jobID) throws Exception {
    +		this.committer = committer;
    +		this.serializer = serializer;
    +		this.id = UUID.randomUUID().toString();
    +		this.committer.setJobId(jobID);
    +		this.committer.createResource();
    +	}
    +
    +	@Override
    +	public void open() throws Exception {
    +		committer.setOperatorId(id);
    +		committer.setOperatorSubtaskId(getRuntimeContext().getIndexOfThisSubtask());
    +		committer.open();
    +	}
    +
    +	public void close() throws Exception {
    +		committer.close();
    +	}
    +
    +	/**
    +	 * Saves a handle in the state.
    +	 *
    +	 * @param checkpointId
    +	 * @throws IOException
    +	 */
    +	private void saveHandleInState(final long checkpointId, final long timestamp) throws
Exception {
    +		//only add handle if a new OperatorState was created since the last snapshot
    +		if (out != null) {
    +			StateHandle<DataInputView> handle = out.closeAndGetHandle();
    +			if (state.pendingHandles.containsKey(checkpointId)) {
    +				//we already have a checkpoint stored for that ID that may have been partially written,
    +				//so we discard this "alternate version" and use the stored checkpoint
    +				handle.discardState();
    +			} else {
    +				state.pendingHandles.put(checkpointId, new Tuple2<>(timestamp, handle));
    +			}
    +			out = null;
    +		}
    +	}
    +
    +	@Override
    +	public StreamTaskState snapshotOperatorState(final long checkpointId, final long timestamp)
throws Exception {
    +		StreamTaskState taskState = super.snapshotOperatorState(checkpointId, timestamp);
    +		saveHandleInState(checkpointId, timestamp);
    +		taskState.setFunctionState(state);
    +		return taskState;
    +	}
    +
    +	@Override
    +	public void restoreState(StreamTaskState state, long recoveryTimestamp) throws Exception
{
    +		super.restoreState(state, recoveryTimestamp);
    +		this.state = (ExactlyOnceState) state.getFunctionState();
    +
    +		out = null;
    +	}
    +
    +	@Override
    +	public void notifyOfCompletedCheckpoint(long checkpointId) throws Exception {
    +		super.notifyOfCompletedCheckpoint(checkpointId);
    +
    +		synchronized (state.pendingHandles) {
    +			Set<Long> pastCheckpointIds = state.pendingHandles.keySet();
    +			Set<Long> checkpointsToRemove = new HashSet<>();
    +			for (Long pastCheckpointId : pastCheckpointIds) {
    +				if (pastCheckpointId <= checkpointId) {
    +					if (!committer.isCheckpointCommitted(pastCheckpointId)) {
    +						Tuple2<Long, StateHandle<DataInputView>> handle = state.pendingHandles.get(pastCheckpointId);
    +						DataInputView in = handle.f1.getState(getUserCodeClassloader());
    +						sendValues(new ReusingMutableToRegularIteratorWrapper<>(new InputViewIterator<>(in,
serializer), serializer), handle.f0);
    +						committer.commitCheckpoint(pastCheckpointId);
    --- End diff --
    
    yes it is synchronous. should it fail an exception is thrown.


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