Instrument node callback functions

instrument.js

const generateId = () => Math.random().toString(36).substring(2, 8) + Math.random().toString(36).substring(2, 8)

function instrumentFunction(name, originalFn, cbPosition = 0) {
  return function enhancedFunction(...args) {
    const ident = generateId()
    const callerLine = `(${new Error().stack.split('\n')[2].trim()})`
    const enhancedCB = function (...cbArgs) {
      console.log(`${ident}: ${name} starting ${callerLine}`)
      try {
         args[cbPosition].bind(this)(...cbArgs)
      }
      finally {
        console.log(`${ident}: ${name} complete ${callerLine}`)
      }
    }
    
    const newArgs = [...args]
    newArgs[cbPosition] = enhancedCB
    
    console.log(`${ident}: ${name} registered ${callerLine}`)
    return originalFn.apply(this, newArgs)
  }
}

const { ClientRequest, IncomingMessage } = require('http')

ClientRequest.prototype.on     = instrumentFunction('ClientRequest.on',     ClientRequest.prototype.on,     1)
ClientRequest.prototype.once   = instrumentFunction('ClientRequest.once',   ClientRequest.prototype.once,   1)
IncomingMessage.prototype.on   = instrumentFunction('IncomingMessage.on',   IncomingMessage.prototype.on,   1)
IncomingMessage.prototype.once = instrumentFunction('IncomingMessage.once', IncomingMessage.prototype.once, 1)

setTimeout = instrumentFunction('setTimeout', setTimeout)
setInterval = instrumentFunction('setInterval', setInterval)