public GetShardIteratorResult unmarshall(JsonUnmarshallerContext context) throws Exception {
GetShardIteratorResult getShardIteratorResult = new GetShardIteratorResult();
int originalDepth = context.getCurrentDepth();
String currentParentElement = context.getCurrentParentElement();
int targetDepth = originalDepth + 1;
JsonToken token = context.getCurrentToken();
if (token == null) token = context.nextToken();
if (token == VALUE_NULL) return null;
while (true) {
if (token == null) break;
if (token == FIELD_NAME || token == START_OBJECT) {
if (context.testExpression("ShardIterator", targetDepth)) {
context.nextToken();
getShardIteratorResult.setShardIterator(
StringJsonUnmarshaller.getInstance().unmarshall(context));
}
} else if (token == END_ARRAY || token == END_OBJECT) {
if (context.getLastParsedParentElement() == null
|| context.getLastParsedParentElement().equals(currentParentElement)) {
if (context.getCurrentDepth() <= originalDepth) break;
}
}
token = context.nextToken();
}
return getShardIteratorResult;
}
private String getShardItertor() {
// either return a cached one or get a new one via a GetShardIterator request.
if (currentShardIterator == null) {
String shardId;
// If ShardId supplied use it, else choose first one
if (!getEndpoint().getShardId().isEmpty()) {
shardId = getEndpoint().getShardId();
} else {
DescribeStreamRequest req1 =
new DescribeStreamRequest().withStreamName(getEndpoint().getStreamName());
DescribeStreamResult res1 = getClient().describeStream(req1);
shardId = res1.getStreamDescription().getShards().get(0).getShardId();
}
LOG.debug("ShardId is: {}", shardId);
GetShardIteratorRequest req =
new GetShardIteratorRequest()
.withStreamName(getEndpoint().getStreamName())
.withShardId(shardId)
.withShardIteratorType(getEndpoint().getIteratorType());
if (hasSequenceNumber()) {
req.withStartingSequenceNumber(getEndpoint().getSequenceNumber());
}
GetShardIteratorResult result = getClient().getShardIterator(req);
currentShardIterator = result.getShardIterator();
}
LOG.debug("Shard Iterator is: {}", currentShardIterator);
return currentShardIterator;
}
/**
* Get the records from the particular shard
*
* @param streamName Name of the stream from where the records to be accessed
* @param recordsLimit Number of records to return from shard
* @param shId Shard Id of the shard
* @param iteratorType Shard iterator type
* @param seqNo Record sequence number
* @return the list of records from the given shard
* @throws AmazonClientException
*/
public List<Record> getRecords(
String streamName,
Integer recordsLimit,
String shId,
ShardIteratorType iteratorType,
String seqNo)
throws AmazonClientException {
assert client != null : "Illegal client";
try {
// Create the GetShardIteratorRequest instance and sets streamName, shardId and iteratorType
// to it
GetShardIteratorRequest iteratorRequest = new GetShardIteratorRequest();
iteratorRequest.setStreamName(streamName);
iteratorRequest.setShardId(shId);
iteratorRequest.setShardIteratorType(iteratorType);
// If the iteratorType is AFTER_SEQUENCE_NUMBER, set the sequence No to the iteratorRequest
if (ShardIteratorType.AFTER_SEQUENCE_NUMBER.equals(iteratorType)
|| ShardIteratorType.AT_SEQUENCE_NUMBER.equals(iteratorType))
iteratorRequest.setStartingSequenceNumber(seqNo);
// Get the Response from the getShardIterator service method & get the shardIterator from that
// response
GetShardIteratorResult iteratorResponse = client.getShardIterator(iteratorRequest);
// getShardIterator() specifies the position in the shard
String iterator = iteratorResponse.getShardIterator();
// Create the GetRecordsRequest instance and set the recordsLimit and iterator
GetRecordsRequest getRequest = new GetRecordsRequest();
getRequest.setLimit(recordsLimit);
getRequest.setShardIterator(iterator);
// Get the Response from the getRecords service method and get the data records from that
// response.
GetRecordsResult getResponse = client.getRecords(getRequest);
return getResponse.getRecords();
} catch (AmazonClientException e) {
throw new RuntimeException(e);
}
}
