| Home | Libraries | People | FAQ | More

## Class interprocess_semaphore

boost::interprocess::interprocess_semaphore

## Synopsis

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

    class interprocess_semaphore {
    public:
      // construct/copy/destruct
      interprocess_semaphore(int);
      ~interprocess_semaphore();

      // public member functions
      void post() ;
      void wait() ;
      bool try_wait() ;
      bool timed_wait(const boost::posix_time::ptime &) ;
    };

## Description

Wraps a interprocess_semaphore that can be placed in shared memory and can be shared between processes. Allows timed lock tries

### `interprocess_semaphore` public construct/copy/destruct

1.     interprocess_semaphore(int initialCount);

   Creates a interprocess_semaphore with the given initial count. interprocess_exception if there is an error.

2.     ~interprocess_semaphore();

   Destroys the interprocess_semaphore. Does not throw

### `interprocess_semaphore` public member functions

1.     void post() ;

   Increments the interprocess_semaphore count. If there are processes/threads blocked waiting for the interprocess_semaphore, then one of these processes will return successfully from its wait function. If there is an error an interprocess_exception exception is thrown.

2.     void wait() ;

   Decrements the interprocess_semaphore. If the interprocess_semaphore value is not greater than zero, then the calling process/thread blocks until it can decrement the counter. If there is an error an interprocess_exception exception is thrown.

3.     bool try_wait() ;

   Decrements the interprocess_semaphore if the interprocess_semaphore's value is greater than zero and returns true. If the value is not greater than zero returns false. If there is an error an interprocess_exception exception is thrown.

4.     bool timed_wait(const boost::posix_time::ptime & abs_time) ;

   Decrements the interprocess_semaphore if the interprocess_semaphore's value is greater than zero and returns true. Otherwise, waits for the interprocess_semaphore to the posted or the timeout expires. If the timeout expires, the function returns false. If the interprocess_semaphore is posted the function returns true. If there is an error throws sem_exception