BulkSynchronous.h

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#ifndef GALOIS_WORKLIST_BULKSYNCHRONOUS_H
#define GALOIS_WORKLIST_BULKSYNCHRONOUS_H

#include "Galois/Runtime/Barrier.h"
#include "Chunked.h"
#include "WLCompileCheck.h"

namespace Galois {
namespace WorkList {

template<class Container=dChunkedFIFO<>, class T=int, bool Concurrent = true>
class BulkSynchronous : private boost::noncopyable {
public:
  template<bool _concurrent>
  struct rethread { typedef BulkSynchronous<Container, T, _concurrent> type; };

  template<typename _T>
  struct retype { typedef BulkSynchronous<typename Container::template retype<_T>::type, _T, Concurrent> type; };

  template<typename _container>
  struct with_container { typedef BulkSynchronous<_container, T, Concurrent> type; };

private:
  typedef typename Container::template rethread<Concurrent>::type CTy;

  struct TLD {
    unsigned round;
    TLD(): round(0) { }
  };

  CTy wls[2];
  Runtime::PerThreadStorage<TLD> tlds;
  Runtime::Barrier& barrier;
  Runtime::LL::CacheLineStorage<volatile long> some;
  volatile bool empty;

 public:
  typedef T value_type;

  BulkSynchronous(): barrier(Runtime::getSystemBarrier()), empty(false) { }

  void push(const value_type& val) {
    wls[(tlds.getLocal()->round + 1) & 1].push(val);
  }

  template<typename ItTy>
  void push(ItTy b, ItTy e) {
    while (b != e)
      push(*b++);
  }

  template<typename RangeTy>
  void push_initial(const RangeTy& range) {
    auto rp = range.local_pair();
    push(rp.first, rp.second);
    tlds.getLocal()->round = 1;
    some.data = true;
  }

  Galois::optional<value_type> pop() {
    TLD& tld = *tlds.getLocal();
    Galois::optional<value_type> r;
    
    while (true) {
      if (empty)
        return r; // empty

      r = wls[tld.round].pop();
      if (r)
        return r;

      barrier.wait();
      if (Runtime::LL::getTID() == 0) {
        if (!some.data)
          empty = true;
        some.data = false; 
      }
      tld.round = (tld.round + 1) & 1;
      barrier.wait();

      r = wls[tld.round].pop();
      if (r) {
        some.data = true;
        return r;
      }
    }
  }
};
GALOIS_WLCOMPILECHECK(BulkSynchronous)

} // end namespace WorkList
} // end namespace Galois

#endif

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