1 /* Copyright (c) 2007-2023. 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 #include "src/kernel/activity/ConditionVariableImpl.hpp"
7 #include "src/kernel/activity/MutexImpl.hpp"
8 #include "src/kernel/activity/Synchro.hpp"
9 #include "src/kernel/actor/SimcallObserver.hpp"
10 #include <cmath> // std::isfinite
12 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(ker_condition, ker_synchro, "Condition variables kernel-space implementation");
14 /********************************* Condition **********************************/
16 namespace simgrid::kernel::activity {
19 * @brief Signalizes a condition.
21 * Signalizes a condition and wakes up a sleeping actor.
22 * If there are no actor sleeping, no action is done.
24 void ConditionVariableImpl::signal()
26 XBT_DEBUG("Signal condition %p", this);
28 /* If there are actors waiting for the condition choose one and try to make it acquire the mutex */
29 if (not sleeping_.empty()) {
30 auto& proc = sleeping_.front();
31 sleeping_.pop_front();
33 /* Destroy waiter's synchronization */
34 proc.waiting_synchro_ = nullptr;
36 /* Now transform the cond wait simcall into a mutex lock one */
37 actor::Simcall* simcall = &proc.simcall_;
38 const auto* observer = dynamic_cast<kernel::actor::ConditionWaitSimcall*>(simcall->observer_);
39 xbt_assert(observer != nullptr);
40 observer->get_mutex()->lock_async(simcall->issuer_)->wait_for(simcall->issuer_, -1);
46 * @brief Broadcasts a condition.
48 * Signal ALL actors waiting on a condition.
49 * If there are no actor waiting, no action is done.
51 void ConditionVariableImpl::broadcast()
53 XBT_DEBUG("Broadcast condition %p", this);
55 /* Signal the condition until nobody is waiting on it */
56 while (not sleeping_.empty())
60 void ConditionVariableImpl::wait(MutexImpl* mutex, double timeout, actor::ActorImpl* issuer)
62 XBT_DEBUG("Wait condition %p", this);
63 xbt_assert(std::isfinite(timeout), "timeout is not finite!");
65 /* If there is a mutex unlock it */
66 if (mutex != nullptr) {
67 xbt_assert(mutex->get_owner() == issuer,
68 "Actor %s cannot wait on ConditionVariable %p since it does not own the provided mutex %p",
69 issuer->get_cname(), this, mutex);
71 mutex->unlock(issuer);
74 SynchroImplPtr synchro(new SynchroImpl([this, issuer]() {
75 this->remove_sleeping_actor(*issuer);
76 auto* observer = dynamic_cast<kernel::actor::ConditionWaitSimcall*>(issuer->simcall_.observer_);
77 xbt_assert(observer != nullptr);
78 observer->set_result(true);
80 synchro->set_host(issuer->get_host()).set_timeout(timeout).start();
81 synchro->register_simcall(&issuer->simcall_);
82 sleeping_.push_back(*issuer);
85 // boost::intrusive_ptr<ConditionVariableImpl> support:
86 void intrusive_ptr_add_ref(ConditionVariableImpl* cond)
88 cond->refcount_.fetch_add(1, std::memory_order_relaxed);
91 void intrusive_ptr_release(ConditionVariableImpl* cond)
93 if (cond->refcount_.fetch_sub(1, std::memory_order_release) == 1) {
94 std::atomic_thread_fence(std::memory_order_acquire);
95 xbt_assert(cond->sleeping_.empty(), "Cannot destroy conditional since someone is still using it");
99 } // namespace simgrid::kernel::activity