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Ruby's sleep is not very accurate and Eventmachine's timer is also not very good. So, If you need to process one periodic job with some interval, this approach might be helpful. There is a compensation for sleep and you just need to define your process.
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| class Service | |
| def initialize | |
| @interval = 1.0 | |
| @start_time = Time.now | |
| end | |
| def start | |
| # Update the start-time | |
| @start_time = Time.now | |
| # run loop | |
| loop do | |
| t_start = Time.now | |
| # process the job | |
| process | |
| elapsed = Time.now - t_start | |
| if elapsed > @interval | |
| puts "Error: Job is bigger than Interval.. #{elapsed}" | |
| end | |
| # apply some compensation. | |
| compensation = (Time.now - @start_time) % @interval | |
| sleep (@interval - compensation) | |
| end | |
| end | |
| def process | |
| raise NotImplementedError | |
| end | |
| end | |
| And then, define your jobs in process method. | |
| class MyService < Service | |
| def initialize | |
| super | |
| @interval = 2.0 | |
| end | |
| def process | |
| puts "time: #{Time.now.to_f.round(3)}" | |
| # do the random job .. it takes upto 1.5 seconds. | |
| sleep rand(150) * 0.01 | |
| end | |
| end | |
| Try to run it.. | |
| service = MyService.new | |
| service.start | |
| And you will get a very accurate intervals | |
| time: 1298615010.271 | |
| time: 1298615011.271 | |
| time: 1298615012.271 | |
| time: 1298615013.271 | |
| time: 1298615014.271 | |
| time: 1298615015.271 | |
| time: 1298615016.271 | |
| time: 1298615017.271 | |
| time: 1298615018.271 | |
| time: 1298615019.271 | |
| time: 1298615020.271 | |
| time: 1298615021.271 | |
| time: 1298615022.271 | |
| time: 1298615023.271 | |
| time: 1298615024.271 | |
| time: 1298615025.271 | |
| time: 1298615026.271 | |
| time: 1298615027.271 | |
| http://soohwan.blogspot.com/2011/02/ruby-periodic-process.html |
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