/*
* Copyright 2012-2013 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Amazon Software License (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/asl/
*
* or in the "license" file accompanying this file. This file 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 com.amazonaws.services.kinesis.clientlibrary.lib.worker;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.amazonaws.services.kinesis.clientlibrary.exceptions.internal.BlockedOnParentShardException;
import com.amazonaws.services.kinesis.clientlibrary.lib.checkpoint.SentinelCheckpoint;
import com.amazonaws.services.kinesis.leases.impl.KinesisClientLease;
import com.amazonaws.services.kinesis.leases.interfaces.ILeaseManager;
/**
* Task to block until processing of all data records in the parent shard(s) is completed.
* We check if we have checkpoint(s) for the parent shard(s).
* If a checkpoint for a parent shard is found, we poll and wait until the checkpoint value is SHARD_END
* (application has checkpointed after processing all records in the shard).
* If we don't find a checkpoint for the parent shard(s), we assume they have been trimmed and directly
* proceed with processing data from the shard.
*/
class BlockOnParentShardTask implements ITask {
private static final Log LOG = LogFactory.getLog(BlockOnParentShardTask.class);
private final ShardInfo shardInfo;
private final ILeaseManager<KinesisClientLease> leaseManager;
private final TaskType taskType = TaskType.BLOCK_ON_PARENT_SHARDS;
// Sleep for this duration if the parent shards have not completed processing, or we encounter an exception.
private final long parentShardPollIntervalMillis;
/**
* @param shardInfo Information about the shard we are working on
* @param leaseManager Used to fetch the lease and checkpoint info for parent shards
* @param parentShardPollIntervalMillis Sleep time if the parent shard has not completed processing
*/
BlockOnParentShardTask(ShardInfo shardInfo,
ILeaseManager<KinesisClientLease> leaseManager,
long parentShardPollIntervalMillis) {
this.shardInfo = shardInfo;
this.leaseManager = leaseManager;
this.parentShardPollIntervalMillis = parentShardPollIntervalMillis;
}
/* (non-Javadoc)
* @see com.amazonaws.services.kinesis.clientlibrary.lib.worker.ITask#call()
*/
@Override
public TaskResult call() {
Exception exception = null;
try {
boolean blockedOnParentShard = false;
for (String shardId : shardInfo.getParentShardIds()) {
KinesisClientLease lease = leaseManager.getLease(shardId);
if (lease != null) {
String checkpoint = lease.getCheckpoint();
if ((checkpoint == null) || (!checkpoint.equals(SentinelCheckpoint.SHARD_END.toString()))) {
LOG.debug("Shard " + shardId + " is not yet done. Its current checkpoint is " + checkpoint);
blockedOnParentShard = true;
exception = new BlockedOnParentShardException("Parent shard not yet done");
break;
} else {
LOG.debug("Shard " + shardId + " has been completely processed.");
}
} else {
LOG.info("No lease found for shard " + shardId + ". Not blocking on completion of this shard.");
}
}
if (!blockedOnParentShard) {
LOG.info("No need to block on parents " + shardInfo.getParentShardIds() + " of shard "
+ shardInfo.getShardId());
return new TaskResult(null);
}
} catch (Exception e) {
LOG.error("Caught exception when checking for parent shard checkpoint", e);
exception = e;
}
try {
Thread.sleep(parentShardPollIntervalMillis);
} catch (InterruptedException e) {
LOG.error("Sleep interrupted when waiting on parent shard(s) of " + shardInfo.getShardId(), e);
}
return new TaskResult(exception);
}
/* (non-Javadoc)
* @see com.amazonaws.services.kinesis.clientlibrary.lib.worker.ITask#getTaskType()
*/
@Override
public TaskType getTaskType() {
return taskType;
}
}