ah-collector

Super light wrapper around async-hooks to collect information about resources created during async operations.

const ActivityCollector = require('ah-collector')

function captureStack(hook, { uid, type, triggerId }, resource) {
  // Predicate to decide if a stack should be captured or not.
  // Capture only inits of the TIMERWRAP but everything of the Timeout.
  return type === 'Timeout' || (type === 'TIMERWRAP' && hook === 'init')
}

const collector = new ActivityCollector({
    start: process.hrtime()
  , captureStack
}).enable()

setTimeout(ontimeout, 100)

function ontimeout() {
  collector
    .processStacks()
    .dump()
}

Requirements

Needs async hooks feature, therefore build from this PR for now.

EPS document

Documentation in progress

Installation

npm install ah-collector

API

ActivityCollector

Creates an instance of an ActivityCollector

Parameters

• $0 Object
  • $0.start Array<Number> start time obtained via process.hrtime()
  • $0.stackCapturer StackCapturer? which is used to decide if a stack should be captured as well as to capture and process it @see thlorenz/ah-stack-capturer The default capturer used doesn't ever capture a stack so this feature is turned off by default. (optional, default defaultStackCapturer)
  • $0.requireInit boolean? when true any activities whose init hook we missed are ignored even if we see before, after and/or destroy hooks. (optional, default false)

Returns ActivityCollector instance of ActivityCollector

activityCollector.enable

Enables the collection of async hooks. Needs to be called as otherwise nothing will be collected.

Returns ActivityCollector activityCollector

activityCollector.disable

Disables the collection of async hooks. Nothing will be collected until activityCollector.enable() is called.

Returns ActivityCollector activityCollector

activityCollector.clear

Clears all currently collected activity.

Returns ActivityCollector activityCollector

activityCollector.activitiesOfTypes

Returns an Array of all activities collected so far that are of the specified type(s).

Parameters

• type (Array<String> | String) the type to match

Returns Array activities matching the specified type(s)

activityCollector.activities

A getter that returns a map of all activities collected so far.

Returns Map activities

activityCollector.activitiesArray

A getter that returns an Array of all activities collected so far.

Returns Array activities

activityCollector.processStacks

Processes all stacks that were captured for specific activities This is done in line, i.e. the actual stacks of the activity objects are modified.

Returns ActivityCollector activityCollector

activityCollector.dump

Dumps all so far collected activities to the console. This is useful for diagnostic purposes.

If no arguments are provided, all activities are dumped.

Parameters

• opts Object allow tweaking which activities are dumped and how
  • opts.types (Array<String> | String) type(s) to dump
  • opts.stage String the stage to print as the title of the dump
  • opts.depth Number the depth with which the dumped object is dumped

Returns ActivityCollector activityCollector

activityCollector.dumpTypes

Dumps all types in the order they were collected including id and trigger id.

Example: FSREQWRAP:id:triggerId

ActivityCollector#UNKNOWN_TYPE

Static getter that denotes the type given to activities whose type is unkown since we missed their init event.

License

MIT