std::counting_semaphore<LeastMaxValue>::try_acquire

 

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线程 thread (C++11) jthread (C++20) hardware_destructive_interference_sizehardware_constructive_interference_size (C++17)(C++17) this_thread 命名空间 get_id (C++11) yield (C++11) sleep_for (C++11) sleep_until (C++11) 协作取消 stop_token (C++20) inplace_stop_token (C++26) never_stop_token (C++26) stop_source (C++20) inplace_stop_source (C++26)   stop_callback (C++20) inplace_stop_callback (C++26) stop_callback_for_t (C++26) stoppable_token (C++26) unstoppable_token (C++26) stoppable-source (C++26) stoppable-callback-for (C++26)   互斥 mutex (C++11) recursive_mutex (C++11) shared_mutex (C++17) timed_mutex (C++11) recursive_timed_mutex (C++11) shared_timed_mutex (C++14) 通用锁管理 lock (C++11) lock_guard (C++11) scoped_lock (C++17) unique_lock (C++11) shared_lock (C++14) once_flag (C++11) call_once (C++11) try_lock (C++11) defer_locktry_to_lockadopt_lockdefer_lock_ttry_to_lock_tadopt_lock_t (C++11)(C++11)(C++11)(C++11)(C++11)(C++11) 条件变量 condition_variable (C++11) condition_variable_any (C++11) notify_all_at_thread_exit (C++11) cv_status (C++11) 信号量 counting_semaphorebinary_semaphore (C++20)(C++20) 闩锁和屏障 latch (C++20) barrier (C++20) 期货 promise (C++11) future (C++11) shared_future (C++11) packaged_task (C++11) async (C++11) launch (C++11) future_status (C++11) future_error (C++11) future_category (C++11) future_errc (C++11) 安全回收 rcu_obj_base (C++26) rcu_domain (C++26) rcu_default_domain (C++26) rcu_synchronize (C++26) rcu_barrier (C++26) rcu_retire (C++26) 危险指针 hazard_pointer_obj_base (C++26) hazard_pointer (C++26) make_hazard_pointer (C++26)

原子类型 atomic (C++11) atomic_ref (C++20) atomic_flag (C++11) 原子类型的初始化 atomic_init (C++11)(C++20 中已弃用) ATOMIC_VAR_INIT (C++11)(C++20 中已弃用) ATOMIC_FLAG_INIT (C++11) 内存排序 memory_order (C++11) kill_dependency (C++11) atomic_thread_fence (C++11) atomic_signal_fence (C++11) 原子操作的自由函数 atomic_storeatomic_store_explicit (C++11)(C++11) atomic_loadatomic_load_explicit (C++11)(C++11) atomic_exchangeatomic_exchange_explicit (C++11)(C++11) atomic_compare_exchange_weakatomic_compare_exchange_weak_explicitatomic_compare_exchange_strongatomic_compare_exchange_strong_explicit (C++11)(C++11)(C++11)(C++11) atomic_fetch_addatomic_fetch_add_explicit (C++11)(C++11) atomic_fetch_subatomic_fetch_sub_explicit (C++11)(C++11) atomic_fetch_andatomic_fetch_and_explicit (C++11)(C++11) atomic_fetch_oratomic_fetch_or_explicit (C++11)(C++11) atomic_fetch_xoratomic_fetch_xor_explicit (C++11)(C++11) atomic_fetch_maxatomic_fetch_max_explicit (C++26)(C++26) atomic_fetch_minatomic_fetch_min_explicit (C++26)(C++26) atomic_is_lock_free (C++11) atomic_waitatomic_wait_explicit (C++20)(C++20) atomic_notify_one (C++20) atomic_notify_all (C++20) 原子标志的自由函数 atomic_flag_test_and_setatomic_flag_test_and_set_explicit (C++11)(C++11) atomic_flag_clearatomic_flag_clear_explicit (C++11)(C++11) atomic_flag_testatomic_flag_test_explicit (C++20)(C++20) atomic_flag_waitatomic_flag_wait_explicit (C++20)(C++20) atomic_flag_notify_one (C++20) atomic_flag_notify_all (C++20)

 

std::counting_semaphore

成员函数

counting_semaphore::counting_semaphore

counting_semaphore::~counting_semaphore

操作

counting_semaphore::release

counting_semaphore::acquire

counting_semaphore::try_acquire

counting_semaphore::try_acquire_for

counting_semaphore::try_acquire_until

常量

counting_semaphore::max

 

bool try_acquire() noexcept;		(自 C++20 起)

尝试原子地将内部计数器减 1，如果它大于 ​0​；无论如何都不会阻塞。

返回值

如果它减小了内部计数器，则为 true，否则为 false.

备注

即使计数器大于 ​0​，实现也允许它无法递减计数器 - 也就是说，它们允许虚假失败并返回 false.

另请参见

release	递增内部计数器并解除获取者的阻塞 (公共成员函数)
acquire	递减内部计数器或阻塞，直到它可以 (公共成员函数)
try_acquire_for	尝试递减内部计数器，阻塞不超过持续时间 (公共成员函数)
try_acquire_until	尝试递减内部计数器，阻塞到某个时间点 (公共成员函数)