SimGrid (3.23.3) NOT RELEASED YET (v3.24 expected September 23. 7:50 UTC)
+S4U:
+ - Barrier::wait returns SG_BARRIER_SERIAL_THREAD for (only) one actor
+ for consistency with pthread_barrier_wait()
+
MSG:
- convert a new set of functions to the S4U C interface and move the old MSG
versions to legacy (MSG_process_self*, MSG_process_{un}ref, ...)
- FG#28: add sg_actor_self (and other wrappers on this_actor methods)
- FG#29 and FG#33: provide a new C API to mutexes and condition variables
- FG#30: convert MSG_process_{un}ref to sg_actor_{un}ref
+ - FG#34: SG_BARRIER_SERIAL_THREAD?
----------------------------------------------------------------------------
#include <atomic>
#include <future>
+constexpr int SG_BARRIER_SERIAL_THREAD = -1;
+
namespace simgrid {
namespace s4u {
private:
MutexPtr mutex_;
ConditionVariablePtr cond_;
- unsigned int expected_processes_;
- unsigned int arrived_processes_ = 0;
+ unsigned int expected_actors_;
+ unsigned int arrived_actors_ = 0;
/* refcounting */
std::atomic_int_fast32_t refcount_{0};
Barrier& operator=(Barrier const&) = delete;
#endif
- /** Constructs a new barrier */
- static BarrierPtr create(unsigned int expected_processes);
-
+ static BarrierPtr create(unsigned int expected_actors);
int wait();
#ifndef DOXYGEN
namespace simgrid {
namespace s4u {
-Barrier::Barrier(unsigned int expected_processes) : mutex_(Mutex::create()), cond_(ConditionVariable::create()), expected_processes_(expected_processes)
+Barrier::Barrier(unsigned int expected_processes)
+ : mutex_(Mutex::create()), cond_(ConditionVariable::create()), expected_actors_(expected_processes)
{
}
*
* See @ref s4u_raii.
*/
-BarrierPtr Barrier::create(unsigned int expected_processes)
+BarrierPtr Barrier::create(unsigned int expected_actors)
{
- return BarrierPtr(new Barrier(expected_processes));
+ return BarrierPtr(new Barrier(expected_actors));
}
-/**
- * Wait functions
+/** @brief Block the current actor until all expected actors reach the barrier.
+ *
+ * This method is meant to be somewhat consistent with the pthread_barrier_wait function.
+ *
+ * @return 0 for all actors but one: exactly one actor will get SG_BARRIER_SERIAL_THREAD as a return value.
*/
int Barrier::wait()
{
mutex_->lock();
- arrived_processes_++;
- XBT_DEBUG("waiting %p %u/%u", this, arrived_processes_, expected_processes_);
- if (arrived_processes_ == expected_processes_) {
+ arrived_actors_++;
+ XBT_DEBUG("waiting %p %u/%u", this, arrived_actors_, expected_actors_);
+ if (arrived_actors_ == expected_actors_) {
cond_->notify_all();
mutex_->unlock();
- arrived_processes_ = 0;
- return -1;
+ arrived_actors_ = 0;
+ return SG_BARRIER_SERIAL_THREAD;
}
cond_->wait(mutex_);