1 /* Copyright (c) 2019-2023. 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 <simgrid/Exception.hpp>
7 #include <simgrid/s4u/Host.hpp>
9 #include "src/kernel/activity/SemaphoreImpl.hpp"
10 #include "src/kernel/activity/Synchro.hpp"
11 #include "src/kernel/actor/SynchroObserver.hpp"
12 #include "src/kernel/resource/CpuImpl.hpp"
14 #include <cmath> // std::isfinite
16 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(ker_semaphore, ker_synchro, "Semaphore kernel-space implementation");
18 namespace simgrid::kernel::activity {
20 /* -------- Acquisition -------- */
22 void SemAcquisitionImpl::wait_for(actor::ActorImpl* issuer, double timeout)
24 xbt_assert(std::isfinite(timeout), "timeout is not finite!");
25 xbt_assert(issuer == issuer_, "Cannot wait on acquisitions created by another actor (id %ld)", issuer_->get_pid());
27 XBT_DEBUG("Wait semaphore %p (timeout:%f)", this, timeout);
29 this->register_simcall(&issuer_->simcall_); // Block on that acquisition
33 } else if (timeout > 0) {
34 model_action_ = get_issuer()->get_host()->get_cpu()->sleep(timeout);
35 model_action_->set_activity(this);
38 // Already in the queue
41 void SemAcquisitionImpl::finish()
43 xbt_assert(simcalls_.size() == 1, "Unexpected number of simcalls waiting: %zu", simcalls_.size());
44 actor::Simcall* simcall = simcalls_.front();
45 simcalls_.pop_front();
47 if (model_action_ != nullptr) { // A timeout was declared
48 if (model_action_->get_state() == resource::Action::State::FINISHED) { // The timeout elapsed
49 if (granted_) { // but we got the semaphore, just in time!
50 set_state(State::DONE);
52 } else { // we have to report that timeout
53 cancel(); // Unregister the acquisition from the semaphore
55 /* Return to the englobing simcall that the wait_for timeouted */
56 auto* observer = dynamic_cast<kernel::actor::SemaphoreAcquisitionObserver*>(get_issuer()->simcall_.observer_);
57 xbt_assert(observer != nullptr);
58 observer->set_result(true);
61 model_action_->unref();
62 model_action_ = nullptr;
65 simcall->issuer_->waiting_synchro_ = nullptr;
66 simcall->issuer_->simcall_answer();
68 void SemAcquisitionImpl::cancel()
70 /* Remove myself from the list of interested parties */
71 const auto* issuer = get_issuer();
72 auto it = std::find_if(semaphore_->ongoing_acquisitions_.begin(), semaphore_->ongoing_acquisitions_.end(),
73 [issuer](SemAcquisitionImplPtr acqui) { return acqui->get_issuer() == issuer; });
74 xbt_assert(it != semaphore_->ongoing_acquisitions_.end(),
75 "Cannot find myself in the waiting queue that I have to leave");
76 semaphore_->ongoing_acquisitions_.erase(it);
79 /* -------- Semaphore -------- */
80 unsigned SemaphoreImpl::next_id_ = 0;
82 SemAcquisitionImplPtr SemaphoreImpl::acquire_async(actor::ActorImpl* issuer)
84 auto res = SemAcquisitionImplPtr(new kernel::activity::SemAcquisitionImpl(issuer, this), true);
90 /* No free token in the semaphore; register the acquisition */
91 ongoing_acquisitions_.push_back(res);
95 void SemaphoreImpl::release()
97 XBT_DEBUG("Sem release semaphore %p", this);
99 if (not ongoing_acquisitions_.empty()) {
100 /* Release the first waiting actor */
102 auto acqui = ongoing_acquisitions_.front();
103 ongoing_acquisitions_.pop_front();
105 acqui->granted_ = true;
106 if (acqui == acqui->get_issuer()->waiting_synchro_)
108 // else, the issuer is not blocked on this acquisition so no need to release it
111 // nobody's waiting here
116 } // namespace simgrid::kernel::activity