57 lines
1.4 KiB
C++
57 lines
1.4 KiB
C++
#include <mutex>
|
|
#include <stdexcept>
|
|
|
|
class hierarchical_mutex
|
|
{
|
|
std::mutex internal_mutex;
|
|
unsigned long const hierarchy_value;
|
|
unsigned long previous_hierarchy_value;
|
|
static thread_local unsigned long this_thread_hierarchy_value;
|
|
|
|
void check_for_hierarchy_violation()
|
|
{
|
|
if(this_thread_hierarchy_value <= hierarchy_value)
|
|
{
|
|
throw std::logic_error("mutex hierarchy violated");
|
|
}
|
|
}
|
|
void update_hierarchy_value()
|
|
{
|
|
previous_hierarchy_value=this_thread_hierarchy_value;
|
|
this_thread_hierarchy_value=hierarchy_value;
|
|
}
|
|
public:
|
|
explicit hierarchical_mutex(unsigned long value):
|
|
hierarchy_value(value),
|
|
previous_hierarchy_value(0)
|
|
{}
|
|
void lock()
|
|
{
|
|
check_for_hierarchy_violation();
|
|
internal_mutex.lock();
|
|
update_hierarchy_value();
|
|
}
|
|
void unlock()
|
|
{
|
|
this_thread_hierarchy_value=previous_hierarchy_value;
|
|
internal_mutex.unlock();
|
|
}
|
|
bool try_lock()
|
|
{
|
|
check_for_hierarchy_violation();
|
|
if(!internal_mutex.try_lock())
|
|
return false;
|
|
update_hierarchy_value();
|
|
return true;
|
|
}
|
|
};
|
|
thread_local unsigned long
|
|
hierarchical_mutex::this_thread_hierarchy_value(ULONG_MAX);
|
|
|
|
int main()
|
|
{
|
|
hierarchical_mutex m1(42);
|
|
hierarchical_mutex m2(2000);
|
|
|
|
}
|