nx_cond.nx

nx_cond.nx -- condition variable on top of nx_mutex + futex. Condition variables let a thread block until another thread signals "the condition you were waiting on is now true". The classic producer/consumer pattern: producer: consumer: mutex.lock mutex.lock queue.push(item) while queue.empty: cond.signal cond.wait(mutex) # atomic unlock+sleep mutex.unlock item = queue.pop mutex.unlock Implementation uses Linux futex with a sequence counter. Each nx_cond_wait reads the current seq, drops the mutex, blocks on futex(seq), then reacquires the mutex on wakeup. signal/broadcast bump seq + futex_wake. Pairs with nx_mutex (the lock you must hold when calling wait / signal) + nx_atom (eventual SMP correctness).