are-we-there-yet
Track complex hierarchies of asynchronous task completion statuses. This is
intended to give you a way of recording and reporting the progress of the big
recursive fan-out and gather type workflows that are so common in async.
What you do with this completion data is up to you, but the most common use case is to
feed it to one of the many progress bar modules.
Most progress bar modules include a rudimentary version of this, but my
needs were more complex.
Usage
var TrackerGroup = require("are-we-there-yet").TrackerGroup
var top = new TrackerGroup("program")
var single = top.newItem("one thing", 100)
single.completeWork(20)
console.log(top.completed())
fs.stat("file", function(er, stat) {
if (er) throw er
var stream = top.newStream("file", stat.size)
console.log(top.completed())
fs.createReadStream("file").pipe(stream).on("data", function (chunk) {
})
top.on("change", function (name) {
})
})
Shared Methods
- var completed = tracker.completed()
Implemented in: Tracker
, TrackerGroup
, TrackerStream
Returns the ratio of completed work to work to be done. Range of 0 to 1.
Implemented in: Tracker
, TrackerGroup
Marks the tracker as completed. With a TrackerGroup this marks all of its
components as completed.
Marks all of the components of this tracker as finished, which in turn means
that tracker.completed()
for this will now be 1.
This will result in one or more change
events being emitted.
Events
All tracker objects emit change
events with the following arguments:
function (name, completed, tracker)
name
is the name of the tracker that originally emitted the event,
or if it didn't have one, the first containing tracker group that had one.
completed
is the percent complete (as returned by tracker.completed()
method).
tracker
is the tracker object that you are listening for events on.
TrackerGroup
Creates a new empty tracker aggregation group. These are trackers whose
completion status is determined by the completion status of other trackers added to this aggregation group.
Ex.
var tracker = new TrackerGroup("parent")
var foo = tracker.newItem("firstChild", 100)
var bar = tracker.newItem("secondChild", 100)
foo.finish()
console.log(tracker.completed())
bar.finish()
console.log(tracker.completed())
Adds the otherTracker to this aggregation group. The weight determines
how long you expect this tracker to take to complete in proportion to other
units. So for instance, if you add one tracker with a weight of 1 and
another with a weight of 2, you're saying the second will take twice as long
to complete as the first. As such, the first will account for 33% of the
completion of this tracker and the second will account for the other 67%.
Returns otherTracker.
- var subGroup = tracker.newGroup(name, weight)
The above is exactly equivalent to:
var subGroup = tracker.addUnit(new TrackerGroup(name), weight)
- var subItem = tracker.newItem(name, todo, weight)
The above is exactly equivalent to:
var subItem = tracker.addUnit(new Tracker(name, todo), weight)
- var subStream = tracker.newStream(name, todo, weight)
The above is exactly equivalent to:
var subStream = tracker.addUnit(new TrackerStream(name, todo), weight)
- console.log( tracker.debug() )
Returns a tree showing the completion of this tracker group and all of its
children, including recursively entering all of the children.
Tracker
Ordinarily these are constructed as a part of a tracker group (via
newItem
).
- var completed = tracker.completed()
Returns the ratio of completed work to work to be done. Range of 0 to 1. If
total work to be done is 0 then it will return 0.
-
tracker.addWork(todo)
- todo A number to add to the amount of work to be done.
Increases the amount of work to be done, thus decreasing the completion
percentage. Triggers a change
event.
Increase the amount of work complete, thus increasing the completion percentage.
Will never increase the work completed past the amount of work todo. That is,
percentages > 100% are not allowed. Triggers a change
event.
Marks this tracker as finished, tracker.completed() will now be 1. Triggers
a change
event.
TrackerStream
The tracker stream object is a pass through stream that updates an internal
tracker object each time a block passes through. It's intended to track
downloads, file extraction and other related activities. You use it by piping
your data source into it and then using it as your data source.
If your data has a length attribute then that's used as the amount of work
completed when the chunk is passed through. If it does not (eg, object
streams) then each chunk counts as completing 1 unit of work, so your size
should be the total number of objects being streamed.
-
tracker.addWork(todo)
- todo Increase the expected overall size by todo bytes.
Increases the amount of work to be done, thus decreasing the completion
percentage. Triggers a change
event.