PhxPtrInterface.h

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#ifndef PHX_PTR_INTERFACE_H
#define PHX_PTR_INTERFACE_H

#include <Phx/PhxConfig.h> // also includes pthread.h
#include <Phx/PhxTypes.h>

namespace Phx {

  template <class T>
  class PtrInterface {
  public:
    typedef uint32_t ReferenceCount;

    PtrInterface(void) : mReferenceCount(0) { }

    void newReference(void) const {
      ++(const_cast<PtrInterface<T>*>(this))->mReferenceCount;
    }

    void deleteReference(void) const {
      PtrInterface<T>* nonConst = const_cast<PtrInterface<T>*>(this);
      --nonConst->mReferenceCount;
      if (nonConst->mReferenceCount == 0) {
        nonConst->onZeroReferenceCount();
      }
    }

    ReferenceCount referenceCount() const { return mReferenceCount; }

  protected:
    // virtual destructor
    virtual ~PtrInterface() {}

  private:
    virtual void onZeroReferenceCount(void) { delete this; }

    // number of references to this object
    ReferenceCount mReferenceCount;
  };


  template <class T>
  class LockedPtrInterface {
  public:
    typedef uint32_t ReferenceCount;

    LockedPtrInterface(void) : mReferenceCount(0) { 
      if (pthread_mutex_init(&mLock, 0) != 0) {
        throw InternalException();
      }
    }

    void newReference(void) const {
      LockedPtrInterface<T>* nonConst = const_cast<LockedPtrInterface<T>*>(this);
      pthread_mutex_lock(&nonConst->mLock);
      ++nonConst->mReferenceCount;
      pthread_mutex_unlock(&nonConst->mLock);
    }

    void deleteReference(void) const {
      LockedPtrInterface<T>* nonConst = const_cast<LockedPtrInterface<T>*>(this);
      pthread_mutex_lock(&nonConst->mLock);
      --nonConst->mReferenceCount;

      if (nonConst->mReferenceCount == 0) {
        pthread_mutex_unlock(&nonConst->mLock);
        nonConst->onZeroReferenceCount();
      } else {
        pthread_mutex_unlock(&nonConst->mLock);
      }
    }

    ReferenceCount referenceCount() const { 
      LockedPtrInterface<T>* nonConst = const_cast<LockedPtrInterface<T>*>(this);
      pthread_mutex_lock(&nonConst->mLock);
      ReferenceCount count = mReferenceCount; 
      pthread_mutex_unlock(&nonConst->mLock);
      return count; 
    }

  protected:
    // virtual destructor - frees mutex
    virtual ~LockedPtrInterface() {
      pthread_mutex_destroy(&mLock);
    }

  private:
    virtual void onZeroReferenceCount(void) { delete this; }

    // number of references to this object
    ReferenceCount mReferenceCount;
    pthread_mutex_t mLock;
  };

}; // namespace Phx

#endif /* PHX_PTR_INTERFACE_H */

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