Create lazy singleton functions with cold-start capabilities.
npm install @kikobeats/cold-start!Last version
> Create lazy singleton functions with cold-start capabilities.
A cold start is the first time your code has been executed in a while (5–25minutes).
This concept has been using for some infrastructure providers, such as:
- AWS Lambda shutting down λ functions after an inactivity time.
- Heroku Dynos sleeping instances after 30 minutes no web traffic activity.
This library brings you this concept to be applied to any piece of software, like:
- Keep up a pool of servers where actually just a few of them are actively used.
- Keep expensive process running that most of the time it isn't being used.
- Wrap some sensible pieces of code that need to be restarted after a while.
The mission of the library is to keep on sync machine resources with real usage.
It's specially useful when you want to shutdown a long-time process that actually is not being used, cutting down infrastructure costs.
``bash`
$ npm install @kikobeats/cold-start --save
`js
const coldStart = require('@kikobeats/cold-start')()
const createBrowserless = require('browserless')
const ms = require('ms')
const getBrowserless = coldStart({
// every cold start function need to have an unique name
name: 'browserless',
// setup lazy intialization, it should be return something to be use into succesive calls
start: createBrowserless,
// setup teardown, if it's necessary
stop: browserless => browserless.destroy(),
// how much idle time to consider the function can be stopped.
duration: ms('5m')
})
;(async () => {
// first call will initialize the cold start function
await getBrowserless()
// succesive calls will reuse the instance
await getBrowserless()
// If the cold start function is not being called in a time window of 5m,
// the cold start function will be destroyed.
// The first call after that will allocate it again
await getBrowserless()
})()
`
It creates a new cold start storage, returning a function to be used for registering any cold start over the storage.
#### options
##### store
Type: object
Default:
It sets the storage to be used for keeping cold start functions running on background.
After initialization, store can be accessed by .store instance method.
##### shutdown
Type: boolean
Default:
It sets the logic to run for shutting down all the cold start functions running.
After initialization, shutdown method can by .shutdown instance method.
It register a new cold start function into the associated storage
#### options
##### name
Required
Type: string
An unique name for identifying the cold start function.
##### start
Required
Type: function
The function to be executed in order of getting the value to be retrieved into the successive function calls.
##### stop
Required
Type: function
A teardown function to be executed before shutdown the cold start function.
##### duration
Required
Type: number`
How much idle time can be considered a cold start function is inactive and should be shutting down.
@kikobeats/cold-start © Kiko Beats, released under the MIT License.
Authored and maintained by Kiko Beats with help from contributors.
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