run_once

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This gem lets a code block run only once every N seconds.

For example:

> loop { RunOnce.in(3) { puts Time.now } }
2011-07-31 10:29:02 +1000
2011-07-31 10:29:05 +1000
2011-07-31 10:29:08 +1000
...

Usage

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First, gem install ‘run_once’. RunOnce uses a text file to keep track of the state and puts it in /tmp by default. The file is locked during update so you can safely use it from multiple threads.

require 'run_once'

RunOnce.use_file = 'run_once.db'
# or
RunOnce.use_path = '/tmp/'

Caller Context

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RunOnce looks at the ruby stack to know where its being called from, so you can use it in different places in the same program.

Sometimes you may set the context manually using with_context(). You can re-use the same context in different places in your program, for example to make sure warning emails of any kind are only sent once every 2 minutes, eg:

RunOnce.with_context('email alert').in(120) { EmailAlert.deliver ... }

Contact the author

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Andrew Snow <andrew@modulus.org> Andys^ on irc.freenode.net