Speed up shutdown and tidy up readme

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 All notable changes to this project will be documented in this file. The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.2.2] - 2020-08-14
+
+### Changed
+
+- Decrease the shutdown time -- the final batch after `CloudWatchWriter.Close()` has been called will be sent as soon as it has been formed, rather than waiting for the next scheduled batch time.
+
 ## [0.2.1] - 2020-08-14
 
 ### Changed

README.md

@@ -107,9 +107,9 @@ To change the batch frequency, you can set the time interval between batches to
 err := cloudWatchWriter.SetBatchInterval(time.Second)
 ```
 If you set it below 200 milliseconds it will return an error.
-This interval is not guaranteed as a long running request to CloudWatch could delay to the next batch.
-This is because CloudWatch expects to receive logs in sequence and not in parallel, so this has been written to send them in sequence.
-
+The batch interval is not guaranteed as two things can alter how often the batches get delivered:
+- as soon as 1MB of logs or 10k logs have accumulated, they are sent (due to AWS restrictions on batch size);
+- we have to send the batches in sequence (an AWS restriction) so a long running request to CloudWatch can delay the next batch.
 
 ## Acknowledgements
 Much thanks has to go to the creator of `zerolog` (https://github.com/rs/zerolog), for creating such a good logger.

cloudwatch_writer.go

@@ -158,8 +158,9 @@ func (c *CloudWatchWriter) queueMonitor() {
 		item := c.queue.Dequeue()
 		if item == nil {
 			// Empty queue, means no logs to process
-			if c.isClosing() && batch == nil {
-				// at this point we've processed all the logs and can safely
+			if c.isClosing() {
+				c.sendBatch(batch)
+				// At this point we've processed all the logs and can safely
 				// close.
 				close(c.done)
 				return