[CAMEL-8421] Add minimum age option to readLock=changed

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 2.15.0
• Component/s: camel-core, camel-ftp
• Estimated Complexity: Unknown
• Assignee: Claus Ibsen
• Reporter: Jyrki Ruuskanen
• Created: 02/Mar/15 13:21
• Updated: 05/Mar/15 06:02
• Resolved: 04/Mar/15 07:29

Description

I'm a fan of noop=true in file consumers since it means I don't have to worry about how many readers I have and where. But eventually I came across a scenario where current features are not sufficient.

Let's say we have a source system which writes files with name <timestamp>_something.xml, and it won't use temp files or .done marker files or anything like that. We want to get the latest file as soon as it's created. Consider the following route:

from("file:////somewhere/data?noop=true&include=.*_something[.]xml&readLock=changed&sortBy=file:name")
	.aggregate(constant(true), new UseLatestAggregationStrategy()).completionFromBatchConsumer()
		.to("amq:topic:something");

When this route is started it will go through the files in order and get the last one. Then it will wait for new files. This works fine as long as the writer is not "slow".

Now, we had cases of incomplete files being read and I was requested to not to read the file before it is 10 minutes old, just in case. If I increase readLockCheckInterval to 10 minutes getting to the latest file at route startup will take close to forever. The current readLock=changed implementation always sleeps for at least one readLockCheckInterval per file.

If we had readLockMinAge option to define the minimum age for the target file the consumer could acquire readLock on the first poll and breeze through the files until too young a file is reached.

The route below would poll a file every 500ms (default poll delay), while the current readLock=changed would take 1500ms (default poll delay + default readLockCheckInterval) per file. Consumer goes through the files until it hits the end and gets the last one as soon as it becomes old enough.

from("file:////somewhere/data?noop=true&include=.*_something[.]xml&readLock=changed&readLockMinAge=600000&sortBy=file:name")
	.aggregate(constant(true), new UseLatestAggregationStrategy()).completionFromBatchConsumer()
		.to("amq:topic:something");