std::defer_lock, std::try_to_lock, std::adopt_lock
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constexpr std::defer_lock_t defer_lock = std::defer_lock_t(); |
(C++11 起) | |
constexpr std::try_to_lock_t try_to_lock = std::try_to_lock_t(); |
(C++11 起) | |
constexpr std::adopt_lock_t adopt_lock = std::adopt_lock_t(); |
(C++11 起) | |
std::defer_lock
, std::try_to_lock
and std::adopt_lock
are instances of empty struct tag types std::defer_lock_t, std::try_to_lock_t and std::adopt_lock_t respectively.
They are used to specify locking strategies for std::lock_guard and std::unique_lock.
类型
|
Effect(s) |
defer_lock_t
|
没有获得互斥体的所有权
原文: do not acquire ownership of the mutex |
try_to_lock_t
|
不阻塞的情况下,试图获取互斥体的所有权
原文: try to acquire ownership of the mutex without blocking |
adopt_lock_t
|
假设调用线程已经拥有互斥体的所有权
原文: assume the calling thread already has ownership of the mutex |
[编辑] 。为例。
#include <mutex> #include <thread> struct bank_account { explicit bank_account(int balance) : balance(balance) {} int balance; std::mutex m; }; void transfer(bank_account &from, bank_account &to, int amount) { // attempt to lock both mutexes without deadlock std::lock(from.m, to.m); // make sure both already-locked mutexes are unlocked when // we're done; if we just used the lock_guard without std::lock // and std::adopt_lock, we might deadlock with other calls to transfer std::lock_guard lock1(from.m, std::adopt_lock); std::lock_guard lock2(to.m, std::adopt_lock); from.balance -= amount; to.balance += amount; } int main() { bank_account my_account(100); bank_account your_account(50); std::thread t1(transfer, my_account, your_account, 10); std::thread t2(transfer, your_account, my_account, 5); t1.join(); t2.join(); }
[编辑] 。另请参阅。
标签类型用于指定锁定策略 原文: tag type used to specify locking strategy (类) | |
构建一个lock_guard,任意给定的互斥锁定 原文: constructs a lock_guard, optionally locking the given mutex (公共成员函数of std::lock_guard )
| |
构建了一个 unique_lock ,可以提供的互斥锁 原文: constructs a unique_lock , optionally locking the supplied mutex (公共成员函数of std::unique_lock )
|