xen-orchestra/@vates/task/.USAGE.md

```js
import { Task } from '@vates/task'

const task = new Task({
  // this object will be sent in the *start* event
  properties: {
    name: 'my task',
  },

  // if defined, a new detached task is created
  //
  // if not defined and created inside an existing task, the new task is considered a subtask
  onProgress(event) {
    // this function is called each time this task or one of it's subtasks change state
    const { id, timestamp, type } = event
    if (type === 'start') {
      const { name, parentId, properties } = event
    } else if (type === 'end') {
      const { result, status } = event
    } else if (type === 'info' || type === 'warning') {
      const { data, message } = event
    } else if (type === 'property') {
      const { name, value } = event
    } else if (type === 'abortionRequested') {
      const { reason } = event
    }
  },
})

// this field is settable once before being observed
task.id

// contains the current status of the task
//
// possible statuses are:
// - pending
// - success
// - failure
task.status

// Triggers the abort signal associated to the task.
//
// This simply requests the task to abort, it will be up to the task to handle or not this signal.
task.abort(reason)

// if fn rejects, the task will be marked as failed
const result = await task.runInside(fn)

// if fn rejects, the task will be marked as failed
// if fn resolves, the task will be marked as succeeded
const result = await task.run(fn)
```

Inside a task:

```js
// the abort signal of the current task if any, otherwise is `undefined`
Task.abortSignal

// sends an info on the current task if any, otherwise does nothing
Task.info(message, data)

// sends an info on the current task if any, otherwise does nothing
Task.warning(message, data)

// attaches a property to the current task if any, otherwise does nothing
//
// the latest value takes precedence
//
// examples:
// - progress
Task.set(property, value)
```

### `combineEvents`

Create a consolidated log from individual events.

It can be used directly as an `onProgress` callback:

```js
import { makeOnProgress } from '@vates/task/combineEvents'

const onProgress = makeOnProgress({
  // This function is called each time a root task starts.
  //
  // It will be called for as many times as there are tasks created with this `onProgress` function.
  onRootTaskStart(taskLog) {
    // `taskLog` is an object reflecting the state of this task and all its subtasks,
    // and will be mutated in real-time to reflect the changes of the task.

    // timestamp at which the task started
    taskLog.start

    // current status of the task as described in the previous section
    taskLog.status

    // undefined or a dictionary of properties attached to the task
    taskLog.properties

    // timestamp at which the abortion was requested, undefined otherwise
    taskLog.abortionRequestedAt

    // undefined or an array of infos emitted on the task
    taskLog.infos

    // undefined or an array of warnings emitted on the task
    taskLog.warnings

    // timestamp at which the task ended, undefined otherwise
    taskLog.end

    // undefined or the result value of the task
    taskLog.result
  },

  // This function is called each time a root task ends.
  onRootTaskEnd(taskLog) {},

  // This function is called each time a root task or a subtask is updated.
  //
  // `taskLog.$root` can be used to uncondionally access the root task.
  onTaskUpdate(taskLog) {},
})

Task.run({ properties: { name: 'my task' }, onProgress }, asyncFn)
```

It can also be fed event logs directly:

```js
import { makeOnProgress } from '@vates/task/combineEvents'

const onProgress = makeOnProgress({ onRootTaskStart, onRootTaskEnd, onTaskUpdate })

eventLogs.forEach(onProgress)
```