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43 lines
1.1 KiB
CoffeeScript
43 lines
1.1 KiB
CoffeeScript
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# A synchronous processing queue. The queue calls process on the arguments,
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# ensuring that process() is only executing once at a time.
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#
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# process(data, callback) _MUST_ eventually call its callback.
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#
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# Example:
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#
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# queue = require 'syncqueue'
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#
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# fn = queue (data, callback) ->
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# asyncthing data, ->
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# callback(321)
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#
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# fn(1)
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# fn(2)
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# fn(3, (result) -> console.log(result))
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#
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# ^--- async thing will only be running once at any time.
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module.exports = (process) ->
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throw new Error('process is not a function') unless typeof process == 'function'
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queue = []
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enqueue = (data, callback) ->
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queue.push [data, callback]
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flush()
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enqueue.busy = false
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flush = ->
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return if enqueue.busy or queue.length == 0
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enqueue.busy = true
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[data, callback] = queue.shift()
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process data, (result...) -> # TODO: Make this not use varargs - varargs are really slow.
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enqueue.busy = false
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# This is called after busy = false so a user can check if enqueue.busy is set in the callback.
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callback.apply null, result if callback
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flush()
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enqueue
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