[GitHub] flink pull request: [FLINK-3257] Add Exactly-Once Processing Guara...

[uce <gi...@git.apache.org>]

Github user uce commented on a diff in the pull request:

    https://github.com/apache/flink/pull/1668#discussion_r57319737
  
    --- Diff: flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/tasks/StreamTask.java ---
    @@ -450,112 +450,121 @@ else if (operator != null) {
     		}
     	}
     
    -	@Override
    -	public boolean triggerCheckpoint(final long checkpointId, final long timestamp) throws Exception {
    -		LOG.debug("Starting checkpoint {} on task {}", checkpointId, getName());
    -		
    -		synchronized (lock) {
    -			if (isRunning) {
    -
    -				// since both state checkpointing and downstream barrier emission occurs in this
    -				// lock scope, they are an atomic operation regardless of the order in which they occur
    -				// we immediately emit the checkpoint barriers, so the downstream operators can start
    -				// their checkpoint work as soon as possible
    -				operatorChain.broadcastCheckpointBarrier(checkpointId, timestamp);
    -				
    -				// now draw the state snapshot
    -				final StreamOperator<?>[] allOperators = operatorChain.getAllOperators();
    -				final StreamTaskState[] states = new StreamTaskState[allOperators.length];
    +	/**
    +	 * Checkpoints all operator states of the current StreamTask. 
    +	 * Thread-safety must be handled outside the scope of this function
    +	 */
    +	protected boolean checkpointStatesInternal(final long checkpointId, long timestamp) throws Exception {
    --- End diff --
    
    What about naming this as in the comments `drawStateSnapshot`? That it is internal is more or less communicated by the fact that it is a `protected` method.


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