Your implementation is correct. The .NET Framework does not provide a built-in concurrent hashset type, unfortunately. However, there are some workarounds. ConcurrentDictionary (recommended) This first one is to use the class ConcurrentDictionary<TKey, TValue> in the namespace System.Collections.Concurrent. In the case, the value is pointless, so we can use a simple byte (1 byte in memory). … Read more
Since C++ 17 (VS2015) you can use the standard: #include <shared_mutex> typedef std::shared_mutex Lock; typedef std::unique_lock< Lock > WriteLock; typedef std::shared_lock< Lock > ReadLock; Lock myLock; void ReadFunction() { ReadLock r_lock(myLock); //Do reader stuff } void WriteFunction() { WriteLock w_lock(myLock); //Do writer stuff } For older compiler versions and standards you can use boost to … Read more
1) Yes, a select with NOLOCK will complete faster than a normal select. 2) Yes, a select with NOLOCK will allow other queries against the effected table to complete faster than a normal select. Why would this be? NOLOCK typically (depending on your DB engine) means give me your data, and I don’t care what … Read more
The difference between a recursive and non-recursive mutex has to do with ownership. In the case of a recursive mutex, the kernel has to keep track of the thread who actually obtained the mutex the first time around so that it can detect the difference between recursion vs. a different thread that should block instead. … Read more
You can’t pass normal multiprocessing.Lock objects to Pool methods, because they can’t be pickled. There are two ways to get around this. One is to create Manager() and pass a Manager.Lock(): def main(): iterable = [1, 2, 3, 4, 5] pool = multiprocessing.Pool() m = multiprocessing.Manager() l = m.Lock() func = partial(target, l) pool.map(func, iterable) … Read more
The activity class should be inner class and the outter class should extend DeviceAdminReceiver public class adminActivity extends DeviceAdminReceiver { public static class Controller extends Activity { DevicePolicyManager mDPM; ComponentName mDeviceAdminSample; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mDPM = (DevicePolicyManager)getSystemService(Context.DEVICE_POLICY_SERVICE); mDeviceAdminSample = new ComponentName(Controller.this, adminActivity.class); } } } To lock the device write the code … Read more
You can use Darwin notifications, to listen for the events. From my testing on a jailbroken iOS 5.0.1 iPhone 4, I think that one of these events might be what you need: com.apple.springboard.lockstate com.apple.springboard.lockcomplete Note: according to the poster’s comments to a similar question I answered here, this should work on a non-jailbroken phone, too. … Read more
The lock statement is translated by C# 3.0 to the following: var temp = obj; Monitor.Enter(temp); try { // body } finally { Monitor.Exit(temp); } In C# 4.0 this has changed and it is now generated as follows: bool lockWasTaken = false; var temp = obj; try { Monitor.Enter(temp, ref lockWasTaken); // body } finally … Read more
The Wikipedia article on spurious wakeups has this tidbit: The pthread_cond_wait() function in Linux is implemented using the futex system call. Each blocking system call on Linux returns abruptly with EINTR when the process receives a signal. … pthread_cond_wait() can’t restart the waiting because it may miss a real wakeup in the little time it … Read more