How can I compute the closest distance between 2 non-intersecting btCollisionObjects?

[qingyouzhao]

I am looking for a mechanism to calculate if 2 btCollisionObjects are within a certain distance threshold.
In fcl, there is a distance(o1, o2, request, result) api to calculate this.

Is there any equivalent mechanism in bullet collision to achieve this? My current workaround is to use a convex sweep or multiple ray casts from co1 to co2 using the distance threshold as the length of the sweep/ray. I would like to ask if there are more elegant or correct mechanism to utilize?