public ScalingOperationReport updateShardCount()

in src/main/java/com/amazonaws/services/kinesis/scaling/StreamScaler.java [441:493]
35 lines of code
9 McCabe index (conditional complexity)

	public ScalingOperationReport updateShardCount(String streamName, int currentShardCount, int targetShardCount,
			Integer minShards, Integer maxShards, boolean waitForCompletion) throws Exception {
		ScaleDirection scaleDirection = getScaleDirection(currentShardCount, targetShardCount);
		if (scaleDirection == ScaleDirection.NONE) {
			LOG.info(String.format("No Scaling Action being taken as current and target Shard count = %s",
					currentShardCount));
			return reportFor(ScalingCompletionStatus.NoActionRequired, streamName, 0, ScaleDirection.NONE);
		}

		// catch already at minimum
		if (targetShardCount < 1) {
			throw new AlreadyOneShardException();
		}

		// ensure we stay between min/max
		if (minShards != null && targetShardCount < minShards) {
			targetShardCount = minShards;
		} else if (maxShards != null && targetShardCount > maxShards) {
			targetShardCount = maxShards;
		}

		try {
			LOG.info(String.format("Updating Stream %s Shard Count to %s", streamName, targetShardCount));

			UpdateShardCountRequest req = UpdateShardCountRequest.builder()
					.scalingType(ScalingType.UNIFORM_SCALING).streamName(streamName)
					.targetShardCount(targetShardCount).build();
			this.kinesisClient.updateShardCount(req);

			// block until the stream transitions back to active state
			LOG.info("Waiting for Stream to transition back to Active Status");
			StreamScalingUtils.waitForStreamStatus(this.kinesisClient, streamName, "ACTIVE");

			// return the current state of the stream
			if (waitForCompletion) {
				return reportFor(ScalingCompletionStatus.Ok, streamName, 1, scaleDirection);
			} else {
				return null;
			}
		} catch (InvalidArgumentException | LimitExceededException ipe) {
			// this will be raised if the scaling operation we are
			// trying to make is not within the limits of the
			// UpdateShardCount API
			// http://docs.aws.amazon.com/kinesis/latest/APIReference/API_UpdateShardCount.html
			//
			// so now we'll default back to the split/merge way
			// return the current state of the stream
			LOG.info("UpdateShardCount API Limit Exceeded. Falling back to manual scaling");

			return scaleStream(streamName, currentShardCount, targetShardCount, 0, 0,
					System.currentTimeMillis(), minShards, maxShards);
		}
	}