public static Map getOpenShards()

in src/main/java/com/amazonaws/services/kinesis/aggregators/StreamAggregatorUtils.java [311:380]
55 lines of code
11 McCabe index (conditional complexity)

	public static Map<String, Shard> getOpenShards(
			AmazonKinesisClient kinesisClient, String streamName)
			throws Exception {
		Map<String, Shard> shardMap = new LinkedHashMap<>();
		final int BACKOFF_MILLIS = 10;
		final int MAX_DESCRIBE_ATTEMPTS = 10;
		int describeAttempts = 0;
		StreamDescription stream = null;
		try {
			do {
				try {
					stream = kinesisClient.describeStream(streamName)
							.getStreamDescription();
				} catch (LimitExceededException e) {
					Thread.sleep(2 ^ describeAttempts * BACKOFF_MILLIS);
					describeAttempts++;
				}
			} while (stream == null && describeAttempts < MAX_DESCRIBE_ATTEMPTS);
		} catch (InterruptedException e) {
			LOG.error(e);
			throw e;
		}

		if (stream == null) {
			throw new Exception(String.format(
					"Unable to describe Stream after %s attempts",
					MAX_DESCRIBE_ATTEMPTS));
		}
		Collection<String> openShardNames = new ArrayList<String>();

		// load all the shards on the stream
		for (Shard shard : stream.getShards()) {
			openShardNames.add(shard.getShardId());
			shardMap.put(shard.getShardId(), shard);

			// remove this shard's parents from the set of active shards -
			// we
			// can't do anything to them
			if (shard.getParentShardId() != null) {
				openShardNames.remove(shard.getParentShardId());
			}
			if (shard.getAdjacentParentShardId() != null) {
				openShardNames.remove(shard.getAdjacentParentShardId());
			}
		}

		// create a List of Open shards for sorting
		List<Shard> shards = new ArrayList<Shard>();
		for (String s : openShardNames) {
			shards.add(shardMap.get(s));
		}

		// sort the list into lowest start hash order
		Collections.sort(shards, new Comparator<Shard>() {
			public int compare(Shard o1, Shard o2) {
				return new BigInteger(o1.getHashKeyRange().getStartingHashKey())
						.compareTo(new BigInteger(o2.getHashKeyRange()
								.getStartingHashKey()));
			}
		});

		// rebuild the shard map into the correct order
		shardMap.clear();
		for (Shard s : shards) {
			shardMap.put(s.getShardId(), s);
		}

		return shardMap;

	}