1 /* Copyright (c) 2006-2019. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #ifndef SIMGRID_S4U_SEMAPHORE_HPP
7 #define SIMGRID_S4U_SEMAPHORE_HPP
9 #include <simgrid/forward.h>
10 #include <simgrid/simix.h>
15 /** @brief A classical semaphore, but blocking in the simulation world
18 * It is strictly impossible to use a real semaphore, such as
19 * <a href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/sem_init.html">sem_init</a>,
20 * because it would block the whole simulation.
21 * Instead, you should use the present class, that offers a very similar interface.
23 * As for any S4U object, Semaphores are using the @ref s4u_raii "RAII idiom" for memory management.
24 * Use #create() to get a simgrid::s4u::SemaphorePtr to a newly created semaphore
25 * and only manipulate simgrid::s4u::SemaphorePtr.
28 class XBT_PUBLIC Semaphore {
30 std::atomic_int_fast32_t refcount_{0};
32 friend void intrusive_ptr_add_ref(Semaphore* sem);
33 friend void intrusive_ptr_release(Semaphore* sem);
36 explicit Semaphore(unsigned int initial_capacity);
40 /** You cannot create a new semaphore by copying an existing one. Use SemaphorePtr instead */
41 Semaphore(Semaphore const&) = delete;
42 /** You cannot create a new semaphore by value assignment either. Use SemaphorePtr instead */
43 Semaphore& operator=(Semaphore const&) = delete;
45 /** Constructs a new semaphore */
46 static SemaphorePtr create(unsigned int initial_capacity);
49 int acquire_timeout(double timeout);
56 } // namespace simgrid
58 #endif /* SIMGRID_S4U_SEMAPHORE_HPP */