Lifo.h

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#ifndef GALOIS_WORKLIST_LIFO_H
#define GALOIS_WORKLIST_LIFO_H

#include "Galois/Runtime/ll/PaddedLock.h"
#include "WLCompileCheck.h"
#include <deque>

namespace Galois {
namespace WorkList {

template<typename T = int, bool Concurrent = true>
struct LIFO : private boost::noncopyable, private Runtime::LL::PaddedLock<Concurrent> {
  template<bool _concurrent>
  struct rethread { typedef LIFO<T, _concurrent> type; };

  template<typename _T>
  struct retype { typedef LIFO<_T, Concurrent> type; };

private:
  std::deque<T> wl;

  using Runtime::LL::PaddedLock<Concurrent>::lock;
  using Runtime::LL::PaddedLock<Concurrent>::try_lock;
  using Runtime::LL::PaddedLock<Concurrent>::unlock;

public:
  typedef T value_type;

  void push(const value_type& val) {
    lock();
    wl.push_back(val);
    unlock();
  }

  template<typename Iter>
  void push(Iter b, Iter e) {
    lock();
    wl.insert(wl.end(),b,e);
    unlock();
  }

  template<typename RangeTy>
  void push_initial(const RangeTy& range) {
    if (Runtime::LL::getTID() == 0)
      push(range.begin(), range.end());
  }

  Galois::optional<value_type> steal(LIFO& victim, bool half, bool pop) {
    Galois::optional<value_type> retval;
    //guard against self stealing
    if (&victim == this) return retval;
    //Ordered lock to preent deadlock
    if (!Runtime::LL::TryLockPairOrdered(*this, victim)) return retval;
    if (half) {
      typename std::deque<T>::iterator split = split_range(victim.wl.begin(), victim.wl.end());
      wl.insert(wl.end(), victim.wl.begin(), split);
      victim.wl.erase(victim.wl.begin(), split);
    } else {
      if (wl.empty()) {
        wl.swap(victim.wl);
      } else {
        wl.insert(wl.end(), victim.wl.begin(), victim.wl.end());
        victim.wl.clear();
      }
    }
    if (pop && !wl.empty()) {
      retval = wl.back();
      wl.pop_back();
    }
    UnLockPairOrdered(*this, victim);
    return retval;
  }

  Galois::optional<value_type> pop()  {
    Galois::optional<value_type> retval;
    lock();
    if (!wl.empty()) {
      retval = wl.back();
      wl.pop_back();
    }
    unlock();
    return retval;
  }
};
GALOIS_WLCOMPILECHECK(LIFO)


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

#endif

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