1   
//
1   
//
2   
// Copyright (c) 2026 Michael Vandeberg
2   
// Copyright (c) 2026 Michael Vandeberg
3   
//
3   
//
4   
// Distributed under the Boost Software License, Version 1.0. (See accompanying
4   
// Distributed under the Boost Software License, Version 1.0. (See accompanying
5   
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
5   
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6   
//
6   
//
7   
// Official repository: https://github.com/cppalliance/corosio
7   
// Official repository: https://github.com/cppalliance/corosio
8   
//
8   
//
9  
9  
10   
#ifndef BOOST_COROSIO_DETAIL_CONDITIONALLY_ENABLED_EVENT_HPP
10   
#ifndef BOOST_COROSIO_DETAIL_CONDITIONALLY_ENABLED_EVENT_HPP
11   
#define BOOST_COROSIO_DETAIL_CONDITIONALLY_ENABLED_EVENT_HPP
11   
#define BOOST_COROSIO_DETAIL_CONDITIONALLY_ENABLED_EVENT_HPP
12  
12  
13   
#include <boost/corosio/detail/conditionally_enabled_mutex.hpp>
13   
#include <boost/corosio/detail/conditionally_enabled_mutex.hpp>
14  
14  
15   
#include <chrono>
15   
#include <chrono>
16   
#include <condition_variable>
16   
#include <condition_variable>
17  
17  
18   
namespace boost::corosio::detail {
18   
namespace boost::corosio::detail {
19  
19  
20   
/* Condition variable wrapper that becomes a no-op when disabled.
20   
/* Condition variable wrapper that becomes a no-op when disabled.
21  
21  
22   
   When enabled, notify/wait delegate to an underlying
22   
   When enabled, notify/wait delegate to an underlying
23   
   std::condition_variable. When disabled, all operations
23   
   std::condition_variable. When disabled, all operations
24   
   are no-ops. The wait paths are unreachable in
24   
   are no-ops. The wait paths are unreachable in
25   
   single-threaded mode because the task sentinel prevents
25   
   single-threaded mode because the task sentinel prevents
26   
   the empty-queue state in do_one().
26   
   the empty-queue state in do_one().
27   
*/
27   
*/
28   
class conditionally_enabled_event
28   
class conditionally_enabled_event
29   
{
29   
{
30   
    std::condition_variable cond_;
30   
    std::condition_variable cond_;
31   
    bool enabled_;
31   
    bool enabled_;
32  
32  
33   
public:
33   
public:
34   
    explicit conditionally_enabled_event(bool enabled = true) noexcept
34   
    explicit conditionally_enabled_event(bool enabled = true) noexcept
35   
        : enabled_(enabled)
35   
        : enabled_(enabled)
36   
    {
36   
    {
37   
    }
37   
    }
38  
38  
39   
    conditionally_enabled_event(conditionally_enabled_event const&)            = delete;
39   
    conditionally_enabled_event(conditionally_enabled_event const&)            = delete;
40   
    conditionally_enabled_event& operator=(conditionally_enabled_event const&) = delete;
40   
    conditionally_enabled_event& operator=(conditionally_enabled_event const&) = delete;
41  
41  
42   
    void set_enabled(bool v) noexcept
42   
    void set_enabled(bool v) noexcept
43   
    {
43   
    {
44   
        enabled_ = v;
44   
        enabled_ = v;
45   
    }
45   
    }
46  
46  
47   
    void notify_one()
47   
    void notify_one()
48   
    {
48   
    {
49   
        if (enabled_)
49   
        if (enabled_)
50   
            cond_.notify_one();
50   
            cond_.notify_one();
51   
    }
51   
    }
52  
52  
53   
    void notify_all()
53   
    void notify_all()
54   
    {
54   
    {
55   
        if (enabled_)
55   
        if (enabled_)
56   
            cond_.notify_all();
56   
            cond_.notify_all();
57   
    }
57   
    }
58  
58  
59   
    void wait(conditionally_enabled_mutex::scoped_lock& lock)
59   
    void wait(conditionally_enabled_mutex::scoped_lock& lock)
60   
    {
60   
    {
61   
        if (enabled_)
61   
        if (enabled_)
62   
            cond_.wait(lock.underlying());
62   
            cond_.wait(lock.underlying());
63   
    }
63   
    }
64  
64  
65   
    template<class Rep, class Period>
65   
    template<class Rep, class Period>
66   
    void wait_for(
66   
    void wait_for(
67   
        conditionally_enabled_mutex::scoped_lock& lock,
67   
        conditionally_enabled_mutex::scoped_lock& lock,
68   
        std::chrono::duration<Rep, Period> const& d)
68   
        std::chrono::duration<Rep, Period> const& d)
69   
    {
69   
    {
70   
        if (enabled_)
70   
        if (enabled_)
71   
            cond_.wait_for(lock.underlying(), d);
71   
            cond_.wait_for(lock.underlying(), d);
72   
    }
72   
    }
73   
};
73   
};
74  
74  
75   
} // namespace boost::corosio::detail
75   
} // namespace boost::corosio::detail
76  
76  
77   
#endif // BOOST_COROSIO_DETAIL_CONDITIONALLY_ENABLED_EVENT_HPP
77   
#endif // BOOST_COROSIO_DETAIL_CONDITIONALLY_ENABLED_EVENT_HPP