mutex

问题 Here's the code where I'me trying to impersonate a user and then create a mutex. The mutex is not getting created. I get ERROR_ACCESS_DENIED error. void Impersonate() { DWORD logonType = LOGON32_LOGON_INTERACTIVE; DWORD logonProvider = LOGON32_PROVIDER_DEFAULT; HANDLE userToken; HANDLE hMutex; DWORD err; LPSTR user = "zoom"; // the user I created myself on my machine. // It has Administrator privileges, and my account, // from which I start the app, is Admin too LPSTR password = "zoom"; LPSTR

问题 Currently studying about std::mutex and would love some help. If I've a code that looks like - .... if(returnBoolValue()) { std::lock_guard<std::mutex> lock(mutex_var); .... .... } .... is the std::lock_guard guarding the function returning the value inside if condition? ie. returnBoolValue() And how should I improve it so that function call is inside the guard as well, if possible? std::mutex - http://en.cppreference.com/w/cpp/thread/mutex std::lock_guard - http://en.cppreference.com/w/cpp

问题 In the classic problem of transferring money from one bank account to another, the accepted solution (I believe) is to associate a mutex with each bank account, then lock both before withdrawing the money from one account and depositing it into the other. At first blush, I'd do it like this: class Account { public: void deposit(const Money& amount); void withdraw(const Money& amount); void lock() { m.lock(); } void unlock() { m.unlock(); } private: std::mutex m; }; void transfer(Account& src,

问题 In the classic problem of transferring money from one bank account to another, the accepted solution (I believe) is to associate a mutex with each bank account, then lock both before withdrawing the money from one account and depositing it into the other. At first blush, I'd do it like this: class Account { public: void deposit(const Money& amount); void withdraw(const Money& amount); void lock() { m.lock(); } void unlock() { m.unlock(); } private: std::mutex m; }; void transfer(Account& src,

问题 The context is like this: a thread tries to lock a already locked mutex the thread is put to sleep/blocking after some while, the mutex is unlocked Q1) What will happen then ? will the thread be immediately put back to running? Or kernel will still wait the running thread consume its time slice and schedule the waiting thread normally? Q2) What if the mutex is not unlocked forever? How does the kernel determine to keep the thread waiting? 回答1: Will the thread be immediately put back to

问题 I was trying to get the exclusive lock for the SQLite database. I used sqlite3_db_mutex(db); and sqlite3_mutex_try(mutexObj) function to acquire lock, but when I tried to execute query from other shell to the same database, I was able insert row in the table,read the data from table I want is to get the LOCK to the database, so that during that time, no-one can make any change to the database, while I've acquired the lock. It is possible in Sqlite ???? 回答1: sqlite3_db_mutex locks that

问题 pthread supports static initialization of pthread_mutex_t using PTHREAD_MUTEX_INITIALIZER. Is it possible to achieve a similar static mechanism for mutex initialization using Windows mutex? 回答1: No, since Windows mutex are handles, they must be initialized with CreateMutex(). Note that the static initialization of pthread_mutex_t using PTHREAD_MUTEX_INITIALIZER is not a real init, it will be done internally at the first call to pthread_mutex_lock() or pthread_mutex_trylock() 回答2: Yes, this is

问题 I have this pretty straightforward piece of code that very rarely throws "System.ApplicationException : Object synchronization method was called from an unsynchronized block of code." when ReleaseMutex () is called. I logically analyzed the flow of the method and just cannot understand how/why this could happen. To my understanding, the ownership of mutex is guaranteed in this case: readonly string mutexKey; public Logger(string dbServer, string dbName) { this.mutexKey = ServiceManagerHelper

问题 I have this pretty straightforward piece of code that very rarely throws "System.ApplicationException : Object synchronization method was called from an unsynchronized block of code." when ReleaseMutex () is called. I logically analyzed the flow of the method and just cannot understand how/why this could happen. To my understanding, the ownership of mutex is guaranteed in this case: readonly string mutexKey; public Logger(string dbServer, string dbName) { this.mutexKey = ServiceManagerHelper

问题 Hi I have a situation in which I have to allow only one thread to say update a variable. There is a trigger, which might invoke multiple threads to update this variable, however the update should happen only once by the first thread whichever arrives at the critical section. Ideally the flow should be like follows: Thread-1; Thread-2 and Thread-3 are invoked to update a variable in critical section guarded by a lock or a mutex Critical section using this guard allows only one thread to enter,