flink-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From StephanEwen <...@git.apache.org>
Subject [GitHub] flink pull request: [streaming] New Source and state checkpointing...
Date Mon, 04 May 2015 13:05:06 GMT
Github user StephanEwen commented on a diff in the pull request:

    --- Diff: flink-staging/flink-streaming/flink-streaming-core/src/main/java/org/apache/flink/streaming/api/checkpoint/Checkpointed.java
    @@ -0,0 +1,53 @@
    + * 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.flink.streaming.api.checkpoint;
    +import org.apache.flink.runtime.state.OperatorState;
    + * This method must be implemented by functions that have state that needs to be
    + * checkpointed. The functions get a call whenever a checkpoint should take place
    + * and return a snapshot of their state, which will be checkpointed.
    + * 
    + * <p>This interface marks a function as <i>synchronously</i> checkpointed.
While the
    + * state is written, the function is not called, so the function needs not return a
    + * copy of its state, but may return a reference to its state. Functions that can
    + * continue to work and mutate the state, even while the state snapshot is being accessed,
    + * can implement the {@link org.apache.flink.streaming.api.checkpoint.CheckpointedAsynchronously}
    + * interface.</p>
    + */
    +public interface Checkpointed {
    +	/**
    +	 * Gets the current operator state as a checkpoint. The state must reflect all operations
    +	 * from all prior operations if this function. 
    +	 * 
    +	 * @param checkpointId The ID of the checkpoint.
    +	 * @param checkpointTimestamp The timestamp of the checkpoint, as derived by
    +	 *                            System.currentTimeMillis() on the JobManager.
    +	 *                            
    +	 * @return A snapshot of the operator state.
    +	 * 
    +	 * @throws Exception Thrown if the creation of the state object failed. This causes
    +	 *                   checkpoint to fail. The system may decide to fail the operation
(and trigger
    +	 *                   recovery), or to discard this checkpoint attempt and to continue
    +	 *                   and to try again with the next checkpoint attempt.
    +	 */
    +	OperatorState<?> snapshotState(long checkpointId, long checkpointTimestamp) throws
    --- End diff --
    The timestamp is the time when the checkpoint was started, assigned by the JobManager,
part of the messages that the tasks receive.
    All barriers emitted into the stream should to have the same timestamp, if we do consistent
"source-assigned event time" - it makes triggering of time-tiggered windows much easier in

If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastructure@apache.org or file a JIRA ticket
with INFRA.

View raw message