class RCULock{
  private:
  // Global state
    Spinlock globalSpin;
    long globalCounter;
  // One per processor
    DEFINE_PER_PROCESSOR(
       static long, quiescentCount); 

  // Per-lock state
    Spinlock writerSpin;

  // Public API omitted
}

void RCULock::ReadLock() {
    disableInterrupts();
}

void RCULock::ReadUnlock() {
    enableInterrupts();
}

// Called by scheduler 
void RCULock::QuiescentState(){ 
    memory_barrier();
    PER_PROC_VAR(quiescentCount) =
                    globalCounter;
    memory_barrier();
}

void RCULock::writeLock() {
    writerSpin.acquire();  
}

void RCULock::writeUnlock() {
    writerSpin.release();
}

void RCULock::publish (void **pp1, 
                         void *p2){
    memory_barrier();
    *pp1 = p2;
    memory_barrier();
}

void
RCULock::synchronize() {
    int p, c;

    globalSpin.acquire(); 
    c = ++globalCounter;
    globalSpin.release(); 

    FOREACH_PROCESSOR(p) {
        while((PER_PROC_VAR(
          quiescentCount, p) - c) < 0) {
            // release CPU for 10ms
            sleep(10); 
        }
    }
}