Adapt.wait should implement a timeout in order to prevent blocking of rendering

[brian-learningpool]

Subject of the enhancement

The Adapt.wait API has begin() and end() calls but in cases where calls to begin() do not have a corresponding call to end() (for whatever reason) it can result in a course failing to load and difficult to diagnose errors.

Your environment

Adapt Framework v3.5.3

Steps to reproduce

Inside a plugin call Adapt.wait.begin() and do not call Adapt.wait.end().

Expected behaviour

After a given timeout, the queue should be flushed together with a debug message logged to the console to indicate as such.

Actual behaviour

The Adapt content appears to get stuck in an intermediate state between loading and rendering.

[brian-learningpool]

Just discussed this with @oliverfoster on Gitter chat. Adapt.wait.for(callback) (and correctly handling the error callback) would have prevented this, but it does make sense to add a timeout.

A 7-second timeout (as used by RequireJS) would be sufficient. This should be reset on every call to begin(). Also, calls to this.end should be wrapped in a _.once().

[oliverfoster]

@brian-learningpool are we ok to remove the 7 seconds now that the xpi begin/wait queue is sorted? or was this for something else?