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Document number: N3817

Date: 2013-10-11

C++ Latches and Barriers

by Alasdair Mackintosh

Excerpt:

We propose a set of commonly-used concurrency classes, some of which may be implemented using efficient lock-free algorithms where appropriate. This paper describes the latch and barrier classes.

Latches are a thread co-ordination mechanism that allow one or more threads to block until an operation is completed. An individual latch is a single-use object; once the operation has been completed, it cannot be re-used.

Barriers are a thread co-ordination mechanism that allow multiple threads to block until an operation is completed. Unlike a latch, a barrier is re-usable; once the operation has been completed, the threads can re-use the same barrier. It is thus useful for managing repeated tasks handled by multiple threads.

A reference implementation of these two classes has been written.