1 /* Copyright (c) 2019-2022. 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 #ifndef SIMGRID_KERNEL_ACTIVITY_SEMAPHOREIMPL_HPP
7 #define SIMGRID_KERNEL_ACTIVITY_SEMAPHOREIMPL_HPP
10 #include <boost/intrusive/list.hpp>
12 #include "simgrid/s4u/Semaphore.hpp"
13 #include "src/kernel/actor/ActorImpl.hpp"
14 #include "src/kernel/actor/SynchroObserver.hpp"
20 /** Semaphore Acquisition: the act / process of acquiring the semaphore.
22 * You can declare some interest on a semaphore without being blocked waiting if it's already empty.
23 * See the documentation of the MutexAcquisitionImpl for further details.
25 class XBT_PUBLIC SemAcquisitionImpl : public ActivityImpl_T<SemAcquisitionImpl> {
26 actor::ActorImpl* issuer_ = nullptr;
27 SemaphoreImpl* semaphore_ = nullptr;
28 bool granted_ = false;
31 friend actor::SemaphoreAcquisitionObserver;
34 SemAcquisitionImpl(actor::ActorImpl* issuer, SemaphoreImpl* sem) : issuer_(issuer), semaphore_(sem) {}
35 SemaphoreImplPtr get_semaphore() { return semaphore_; }
36 actor::ActorImpl* get_issuer() { return issuer_; }
38 bool test(actor::ActorImpl* issuer = nullptr) override { return granted_; }
39 void wait_for(actor::ActorImpl* issuer, double timeout) override;
41 void finish() override;
42 void cancel() override;
43 void set_exception(actor::ActorImpl* issuer) override
48 class XBT_PUBLIC SemaphoreImpl {
49 std::atomic_int_fast32_t refcount_{1};
50 s4u::Semaphore piface_;
52 std::deque<SemAcquisitionImplPtr> ongoing_acquisitions_;
54 static unsigned next_id_;
55 unsigned id_ = next_id_++;
57 friend SemAcquisitionImpl;
58 friend actor::SemaphoreObserver;
61 explicit SemaphoreImpl(unsigned int value) : piface_(this), value_(value){};
63 SemaphoreImpl(SemaphoreImpl const&) = delete;
64 SemaphoreImpl& operator=(SemaphoreImpl const&) = delete;
66 SemAcquisitionImplPtr acquire_async(actor::ActorImpl* issuer);
68 bool would_block() const { return (value_ == 0); }
70 unsigned int get_capacity() const { return value_; }
71 bool is_used() const { return not ongoing_acquisitions_.empty(); }
73 friend void intrusive_ptr_add_ref(SemaphoreImpl* sem)
75 XBT_ATTRIB_UNUSED auto previous = sem->refcount_.fetch_add(1);
76 xbt_assert(previous != 0);
78 friend void intrusive_ptr_release(SemaphoreImpl* sem)
80 if (sem->refcount_.fetch_sub(1) == 1) {
81 xbt_assert(not sem->is_used(), "Cannot destroy semaphore since someone is still using it");
85 unsigned get_id() const { return id_; }
86 s4u::Semaphore& sem() { return piface_; }
88 } // namespace activity
90 } // namespace simgrid
92 #endif /* SIMGRID_KERNEL_ACTIVITY_SEMAPHOREIMPL_HPP */