Barrier, used to synchronize threads

Create a barrier.

Reset to initial (non-triggered) state.

wait b waits for barrier b to be activated by activate b. All threads calling this wait until activate b is called. If b is already activated, wait b does nothing.

activate b unblocks all threads that were waiting on b.

activated b returns true iff activate b was called, and reset b was not called since. In other words, activated b = true means wait b will not block.