lock.hh

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#ifndef TAMER_LOCK_HH
#define TAMER_LOCK_HH 1
/* Copyright (c) 2007-2015, Eddie Kohler
 * Copyright (c) 2007, Regents of the University of California
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, subject to the conditions
 * listed in the Tamer LICENSE file. These conditions include: you must
 * preserve this copyright notice, and you cannot mention the copyright
 * holders in advertising related to the Software without their permission.
 * The Software is provided WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. This
 * notice is a summary of the Tamer LICENSE file; the license in that file is
 * legally binding.
 */
#include <tamer/event.hh>
namespace tamer {

 
class mutex {
  public:
    inline mutex();
 
    inline void acquire(event<> done);
    inline void release();
 
    inline void acquire_shared(event<> done);
    inline void release_shared();
 
  private:
    struct wait {
        wait **pprev;
        wait *next;
        event<> e;
    };
 
    int locked_;
    wait *wait_;
    wait **wait_tailp_;
 
    void acquire(int shared, event<> done);
    class closure__acquire__iQ_;
    void acquire(closure__acquire__iQ_ &);
 
    void wake() {
        if (wait_)
            wait_->e.trigger();
    }
 
    mutex(const mutex &);
    mutex &operator=(const mutex &);
};

inline mutex::mutex()
    : locked_(0), wait_(), wait_tailp_(&wait_) {
}

inline void mutex::acquire(event<> done) {
    acquire(-1, done);
}

inline void mutex::release() {
    assert(locked_ == -1);
    ++locked_;
    wake();
}

inline void mutex::acquire_shared(event<> done) {
    acquire(1, done);
}

inline void mutex::release_shared() {
    assert(locked_ != -1 && locked_ != 0);
    --locked_;
    wake();
}
 
} /* namespace tamer */
#endif /* TAMER_LOCK_HH */