1 /* Copyright (c) 2007-2022. 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 **********************************/
21 * @brief Signalizes a condition.
23 * Signalizes a condition and wakes up a sleeping actor.
24 * If there are no actor sleeping, no action is done.
26 void ConditionVariableImpl::signal()
28 XBT_DEBUG("Signal condition %p", this);
30 /* If there are actors waiting for the condition choose one and try to make it acquire the mutex */
31 if (not sleeping_.empty()) {
32 auto& proc = sleeping_.front();
33 sleeping_.pop_front();
35 /* Destroy waiter's synchronization */
36 proc.waiting_synchro_ = nullptr;
38 /* Now transform the cond wait simcall into a mutex lock one */
39 actor::Simcall* simcall = &proc.simcall_;
40 const auto* observer = dynamic_cast<kernel::actor::ConditionWaitSimcall*>(simcall->observer_);
41 xbt_assert(observer != nullptr);
42 observer->get_mutex()->lock_async(simcall->issuer_)->wait_for(simcall->issuer_, -1);
48 * @brief Broadcasts a condition.
50 * Signal ALL actors waiting on a condition.
51 * If there are no actor waiting, no action is done.
53 void ConditionVariableImpl::broadcast()
55 XBT_DEBUG("Broadcast condition %p", this);
57 /* Signal the condition until nobody is waiting on it */
58 while (not sleeping_.empty())
62 void ConditionVariableImpl::wait(MutexImpl* mutex, double timeout, actor::ActorImpl* issuer)
64 XBT_DEBUG("Wait condition %p", this);
65 xbt_assert(std::isfinite(timeout), "timeout is not finite!");
67 /* If there is a mutex unlock it */
68 if (mutex != nullptr) {
69 xbt_assert(mutex->get_owner() == issuer,
70 "Actor %s cannot wait on ConditionVariable %p since it does not own the provided mutex %p",
71 issuer->get_cname(), this, mutex);
73 mutex->unlock(issuer);
76 SynchroImplPtr synchro(new SynchroImpl([this, issuer]() {
77 this->remove_sleeping_actor(*issuer);
78 auto* observer = dynamic_cast<kernel::actor::ConditionWaitSimcall*>(issuer->simcall_.observer_);
79 xbt_assert(observer != nullptr);
80 observer->set_result(true);
82 synchro->set_host(issuer->get_host()).set_timeout(timeout).start();
83 synchro->register_simcall(&issuer->simcall_);
84 sleeping_.push_back(*issuer);
87 // boost::intrusive_ptr<ConditionVariableImpl> support:
88 void intrusive_ptr_add_ref(ConditionVariableImpl* cond)
90 cond->refcount_.fetch_add(1, std::memory_order_relaxed);
93 void intrusive_ptr_release(ConditionVariableImpl* cond)
95 if (cond->refcount_.fetch_sub(1, std::memory_order_release) == 1) {
96 std::atomic_thread_fence(std::memory_order_acquire);
97 xbt_assert(cond->sleeping_.empty(), "Cannot destroy conditional since someone is still using it");
101 } // namespace activity
102 } // namespace kernel
103 } // namespace simgrid