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## Class named_condition

boost::interprocess::named_condition

## Synopsis

    // In header: <boost/interprocess/sync/named_condition.hpp>

    class named_condition {
    public:
      // types
      typedef unspecified construct_func_t;

      // member classes/structs/unions

      // @ private:

      struct condition_holder {
        interprocess_condition cond_;
      };
      template<typename Lock>
      class lock_inverter {
      public:
        // construct/copy/destruct
        lock_inverter(Lock &);

        // public member functions
        void lock();
        void unlock();
      };

      // construct/copy/destruct
      named_condition();
      named_condition(const named_condition &);
      named_condition(create_only_t, const char *,
                      const permissions & = permissions());
      named_condition(open_or_create_t, const char *,
                      const permissions & = permissions());
      named_condition(open_only_t, const char *);
      named_condition& operator=(const named_condition &);
      ~named_condition();

      // public member functions
      *void notify_one();
      void notify_all();
      template<typename L> void wait(L &);
      template<typename L, typename Pr> void wait(L &, Pr);
      template<typename L> bool timed_wait(L &, const boost::posix_time::ptime &);
      template<typename L, typename Pr>
        bool timed_wait(L &, const boost::posix_time::ptime &, Pr);
      interprocess_condition * condition() const;
      void dont_close_on_destruction();

      // public static functions
      static bool remove(const char *);
      unspecified m_shmem;
    };

## Description

A global condition variable that can be created by name. This condition variable is designed to work with named_mutex and can't be placed in shared memory or memory mapped files.

### `named_condition` public construct/copy/destruct

1.     named_condition();

   @ //Non-copyable

2.     named_condition(const named_condition &);

3.     named_condition(create_only_t create_only, const char * name,
                       const permissions & perm = permissions());

   Creates a global condition with a name. If the condition can't be created throws interprocess_exception

4.     named_condition(open_or_create_t open_or_create, const char * name,
                       const permissions & perm = permissions());

   Opens or creates a global condition with a name. If the condition is created, this call is equivalent to named_condition(create_only_t, ... ) If the condition is already created, this call is equivalent named_condition(open_only_t, ... ) Does not throw

5.     named_condition(open_only_t open_only, const char * name);

   Opens a global condition with a name if that condition is previously created. If it is not previously created this function throws interprocess_exception.

6.     named_condition& operator=(const named_condition &);

7.     ~named_condition();

   @

   Destroys *this and indicates that the calling process is finished using the resource. The destructor function will deallocate any system resources allocated by the system for use by this process for this resource. The resource can still be opened again calling the open constructor overload. To erase the resource from the system use remove().

### `named_condition` public member functions

1.     *void notify_one();

   If there is a thread waiting on *this, change that thread's state to ready. Otherwise there is no effect.

2.     void notify_all();

   Change the state of all threads waiting on *this to ready. If there are no waiting threads, notify_all() has no effect.

3.     template<typename L> void wait(L & lock);

   Releases the lock on the named_mutex object associated with lock, blocks the current thread of execution until readied by a call to this->notify_one() or this->notify_all(), and then reacquires the lock.

4.     template<typename L, typename Pr> void wait(L & lock, Pr pred);

   The same as: while (!pred()) wait(lock)

5.     template<typename L>
         bool timed_wait(L & lock, const boost::posix_time::ptime & abs_time);

   Releases the lock on the named_mutex object associated with lock, blocks the current thread of execution until readied by a call to this->notify_one() or this->notify_all(), or until time abs_time is reached, and then reacquires the lock. Returns: false if time abs_time is reached, otherwise true.

6.     template<typename L, typename Pr>
         bool timed_wait(L & lock, const boost::posix_time::ptime & abs_time,
                         Pr pred);

   The same as: while (!pred()) { if (!timed_wait(lock, abs_time)) return pred(); } return true;

7.     interprocess_condition * condition() const;

8.     void dont_close_on_destruction();

### `named_condition` public static functions

1.     static bool remove(const char * name);

   Erases a named condition from the system. Returns false on error. Never throws.