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    @uswitch/koa-timeout

    1.5.0 • Public • Published

    Koa Timeout

    A Koa middleware to handle timeouts correctly

    How it works | Usage

    Contributors License type language test style

    How it works

    koa-timeout uses Promise.race to race a setTimeout against your Koa middlewares/response.

    Timeout example

    Middlewares
                  A 1s     B 2s       C 3s      D 4s
             ╭─────┴────────┴─────╳╌╌╌╌┴╌╌╌╌╌╌╌╌╌┴╌╌╌╌╌
    Req ─────┤
             ╰────────────────────┬──→ 408 - 2500ms
                               Timeout
                                 2.5s
    

    In this example, a request has come in and the timeout is racing middlewares, A, B, C & D. However, the timeout is triggered causing a 408 response after 2500ms.

    The signifys a short circuit and prevents middlewares C & D from running.

    Successful example

    Middlewares
                  A 1s     B 2s      C 3s      D 4s
             ╭─────┴────────┴─────────┴─────────┴──────╮
             │                                         │
    Req ─────┤                                         ╰──→ 200 - 4500ms
             │
             ╰─────────────────────────────────────────╳╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╮
                                                                         Timeout
                                                                            5s
    

    In this example, all 4 middlewares - A, B, C & D - have finished, resulting in a 200 response after ~4500ms. The timeout is then cleared, signified by the .

    Usage

    The middleware can be configured with a custom timeout time and status code.

    import Koa from 'koa'
    import timeout from '@uswitch/koa-timeout'
    
    const app = new Koa()
    
    app.use(timeout(1000))                     // 1s timeout
    app.use(timeout(1000, { status: 499 }))    // 1s timeout with 499 status

    Short circuiting

    N.B. By default, koa-timeout does not short circuit the other middlewares. This means that the in-flight request will continue to be processed even though a response has already been sent.

    This behaviour can be useful in development to see where the slow parts of the request are, however, in production you probably want to kill the request as soon as possible.

    To enable short circuiting

    This will prevent the next middleware after a timeout from triggering.

    import { shortCircuit } from '@uswitch/koa-timeout'
    
    app.use(timeout(5000))
    
    app.get('*', shortCircuit(handleInitialState))
    app.get('*', shortCircuit(handleRendering))
    app.get('*', shortCircuit(handleReturn))
    
    // Or
    
    app.get('*', ...shortCircuit(handleInitialState, handleRendering, handleReturn))

    N.B. when calling with multiple middlewares, make sure to spread the result! i.e. ...shortCircuit(a, b, c)

    Keywords

    none

    Install

    npm i @uswitch/koa-timeout

    DownloadsWeekly Downloads

    1,751

    Version

    1.5.0

    License

    MIT

    Unpacked Size

    7.21 kB

    Total Files

    4

    Last publish

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