allows for overriding the makeId function

[collin]

This allows for a customized request id generator.

In particular I've been using it with continuation-local-storage to get a "request id" that can be used by any async resource in a given express "request thread"

https://www.npmjs.com/package/continuation-local-storage

A bit like this:

const {
  createNamespace,
  getNamespace,
} = require('continuation-local-storage')
const volleyball = require('volleyball')
const makeId = require('./id')

const express = require('express')

const app = express()

const THREAD_ID_NS = 'THREAD_ID_NS'
const THREAD_ID = 'THREAD_ID'

const threadNS = createNamespace(THREAD_ID_NS)
app.use((req, res, next) => {
  const ns = getNamespace(THREAD_ID_NS)
  ns.bindEmitter(req)
  ns.bindEmitter(res)
  threadNS.run(() => next())
})

app.use(volleyball.custom({
  makeId: () => {
    const ns = getNamespace(THREAD_ID_NS)
    const threadId = makeId()
    ns.set(THREAD_ID, threadId)
    return threadId
  }
}))

function threadNSLogger (...args) {
  const ns = getNamespace(THREAD_ID_NS)
  const id = ns.get(THREAD_ID)
  if (id) {
    console.log(id, ...args)
  }
  else {
    console.log(...args)
  }
}


const Sequelize = require('sequelize')
const db = new Sequelize('postgres://localhost:5432/cls-logger-db', {
  logging: (query) => {
    if (process.env.LOG_SQL === "true") {
      threadNSLogger('——> ' + query)
    }
  }
})

}))

---

Assignee Tasks

• added unit tests
• written relevant docs

[glebec]

I like this feature. Have some nits to pick; in rough order of priority:

• possibly fill in empty test spec
• remove unnecessary export property
• prefer init-time branching
• some small spelling typos
• unnecessary formatting diffs

[glebec]

• makId -> makeId
• funciton -> function

[glebec]

Unnecessary formatting diff * -> - — not a blocker, but also if it can be undone that'd be swell.

[glebec]

More unnecessary * -> - formatting

[glebec]

Why are we adding this to the volleyball instance itself? As I understand it, we only need to make makeId a property of the config passed to volleyball.custom.

[glebec]

• reuests -> requests
• Empty spec; ideally we should capture output and see if the id matches expectations, I guess

[glebec]

The compiler may be able to optimize this, but on principle I'd prefer init-time branching – add the following ca. line 17 (before defining function volleyball):

const idGenerator = config.makeId || makeId

Then cycle would be defined as:

const cycle = {
    log: log,
    id: idGenerator(),
    time: process.hrtime()
}

It may be overkill, but that's how I'd do it (similar to how I instantiate the log function above).

[glebec]

Follow-up, I would also prefer to add a modicum of dynamic type-checking to this config.

if ((makeId in config) && (typeof config.makeId) !== 'function') {
    throw TypeError('Volleyball config option `makeId` must be a function')
}

(untested)