node-modules / ready-callback

Launch server after all async task ready

ready-callback

Launch server after all async task ready

---

Install

$ npm install ready-callback

Usage

Note: ready-callback is using class, so you should use node>=2

var koa = require('koa');
var ready = require('ready-callback')();
var app = koa();
ready.mixin(app);

// register a service
var done = app.readyCallback('service');
serviceLaunch(done);

// callback will be fired after all service launched
app.ready(function() {
  app.listen();
});

Error Handle

If task is called with error, error event will be emit, ready will never be called.

// register a service that will emit error
var done = app.readyCallback('service');
serviceLaunch(function(err) {
  done(err);
});

// listen error event
app.on('error', function(err) {
  // catch error
});

Weak Dependency

If you set a task weak dependency, task will be done without emit error.

var done = app.readyCallback('service', {isWeakDep: true});
serviceLaunch(function(err) {
  done(err);
});

// will be ready
app.ready(function() {
  app.listen();
});

app.on('error', function(err) {
  // never be called
});

You can also set for all ready-callback

var ready = require('ready-callback')({isWeakDep: true});

Ready Status

You can get status every callback end.

app.on('ready_stat', function(data) {
  console.log(data.id); // id of the ended task
  console.log(data.remain); // tasks waiting to be ended
});

Timeout

You can set timeout when a task run a long time.

var ready = require('ready-callback')({timeout: 1000});
ready.mixin(app);
app.on('ready_timeout', function(id) {
  // this will be called after 1s that `service` task don't complete
});

var done = app.readyCallback('service');
serviceLaunch(function() {
  // run a long time
  done();
});

You can also set timeout for every task

ready.mixin(app);
app.on('ready_timeout', function(id) {
  // this will be called after 1s that `service` task don't complete
});

var done = app.readyCallback('service1', {timeout: 1000});
serviceLaunch(done);

lazyStart

You can set a ready-callback object to lazyStart. It will not check ready status immediately, and should start manualy to check ready status.

var ready = require('ready-callback')({ lazyStart: true });
yield sleep(1);
// ready obj is not ready
ready.start();
yield sleep(1);
// ready obj is ready now

LISENCE

Copyright (c) 2015 popomore. Licensed under the MIT license.

Contributors

popomore	fengmk2	semantic-release-bot	greenkeeperio-bot	killagu	liuhanqu

This project follows the git-contributor spec, auto updated at Wed Oct 11 2023 10:27:33 GMT+0800.

ready-callback's Issues

Change url of travis and coveralls

need to refactor with typescript ?

isWeakDep 与 timeout 语义

ready-callback 被广泛应用于控制 app 和 agent 启动。

有时候我们会添加一些弱依赖

const done = app.readyCallback('init xx', { isWeakDep: true, timeout: 3000 });
xx.ready(done);

我们写这段代码的时候，设想的是弱依赖的启动控制项不会影响初始化。

但实际上，如果 xx 启动不成功，在出错或者超时的时候必须 done(err)，app 才会继续启动。

isWeakDep 目前的语义是或略 done 传过来的 err，继续去 ready，但是前提是 done 还是被调用一次。

这个地方很多 plugin 都踩坑了，也就是说我们以为的弱依赖都变成了强依赖(因为没有保证一定 done)。

@popomore 是否要改进一下 ready-callback，变成 timeout 之后就继续 ready 并不再等 done 被调用.

docs typo

Remove -g flag in the npm install command of the Installation section.