NAME¶

std::recursive_mutex::try_lock - std::recursive_mutex::try_lock

Synopsis¶

bool try_lock(); (since C++11)

Tries to lock the mutex. Returns immediately. On successful lock acquisition returns
true, otherwise returns false.

This function is allowed to fail spuriously and return false even if the mutex is
not currently locked by any other thread.

A thread may call try_lock on a recursive mutex repeatedly. Successful calls to
try_lock increment the ownership count: the mutex will only be released after the
thread makes a matching number of calls to unlock.

The maximum number of levels of ownership is unspecified. A call to try_lock will
return false if this number is exceeded.

Prior unlock() operation on the same mutex synchronizes-with (as defined in
std::memory_order) this operation if it returns true. Note that prior lock() does
not synchronize with this operation if it returns false.

Parameters¶

(none)

Return value¶

true if the lock was acquired successfully, otherwise false.

Exceptions¶

Throws nothing.

Example¶

// Run this code

#include <iostream>
#include <mutex>

int main()
{
std::recursive_mutex test;
if (test.try_lock()) {
std::cout << "lock acquired\n";
test.unlock();
} else {
std::cout << "lock not acquired\n";
}

test.lock();
// non-recursive mutex would return false from try_lock now
if (test.try_lock()) {
std::cout << "lock acquired\n";
test.unlock();
} else {
std::cout << "lock not acquired\n";
}
test.unlock();
}

Output:¶

lock acquired
lock acquired

See also¶

lock locks the mutex, blocks if the mutex is not available
(public member function)
unlock unlocks the mutex
(public member function)