diff --git a/include/qutex.h b/include/qutex.h new file mode 100644 index 0000000..ec32f09 --- /dev/null +++ b/include/qutex.h @@ -0,0 +1,139 @@ +#ifndef QUTEX_H +#define QUTEX_H + +#include +#include +#include +#include + +namespace smo { + +// Forward declarations +class LockerAndInvoker; + +/** + * @brief Qutex - Queue-based mutex for asynchronous lock management + * + * A Qutex combines a spinlock, an ownership flag, and a queue of waiting + * lockvokers to provide efficient asynchronous lock management with + * priority-based acquisition for LockSets. + */ +class Qutex +{ +public: + typedef std::list> LockerAndInvokerList; + + /** + * @brief Constructor + */ + Qutex() + { + // TODO: Initialize member variables + } + + /** + * @brief Register a lockvoker in the queue + * @param lockvoker The lockvoker to register + * @return Iterator pointing to the registered lockvoker in the queue + */ + LockerAndInvokerList::iterator registerInQueue( + const std::shared_ptr &lockvoker + ) + { + // TODO: Implement registration logic + // - Acquire the spinlock + // - Insert lockvoker at the rear of the queue + // - Return iterator to the inserted element + // - Release the spinlock + lock.acquire(); + auto it = queue.insert(queue.end(), lockvoker); + lock.release(); + return it; + } + + /** + * @brief Unregister a lockvoker from the queue + * @param it Iterator pointing to the lockvoker to unregister + */ + void unregisterFromQueue(LockerAndInvokerList::iterator it) + { + // TODO: Implement unregistration logic + // - Acquire the spinlock + // - Erase the element at the given iterator + // - Release the spinlock + (void)it; // Suppress unused parameter warning + } + + /** + * @brief Try to acquire the lock for a lockvoker + * @param tryingLockvoker The lockvoker attempting to acquire the lock + * @param nRequiredLocks Number of locks required by the lockvoker's LockSet + * @return true if the lock was successfully acquired, false otherwise + */ + bool tryAcquire(LockerAndInvoker &tryingLockvoker, int nRequiredLocks) + { + // TODO: Implement acquisition logic + // - Acquire the spinlock + // - Check if lock is already owned + // - For single-lock requests, grant immediately if available + // - For multi-lock requests, check if in top X% of queue + // - Set isOwned flag if successful + // - Release the spinlock + // - Return success/failure + (void)tryingLockvoker; // Suppress unused parameter warning + (void)nRequiredLocks; // Suppress unused parameter warning + return false; // Placeholder return value + } + + /** + * @brief Handle backoff when a lockvoker fails to acquire all required locks + * @param failedAcquirer The lockvoker that failed to acquire all locks + */ + void backoff(LockerAndInvoker &failedAcquirer) + { + // TODO: Implement backoff logic + // - Acquire the spinlock + // - If failedAcquirer is at front, rotate queue items + // - Move failedAcquirer to appropriate position in queue + // - Release the spinlock + // - Wake up the new front item + (void)failedAcquirer; // Suppress unused parameter warning + } + + /** + * @brief Release the lock and wake up the next waiting lockvoker + * @param prevOwner The lockvoker that previously owned the lock + */ + void release(LockerAndInvoker &prevOwner) + { + // TODO: Implement release logic + // - Acquire the spinlock + // - Unregister the previous owner from the queue + // - Clear the isOwned flag + // - Get the new front item + // - Release the spinlock + // - Wake up the new front item (conditionally) + (void)prevOwner; // Suppress unused parameter warning + } + + /** + * @brief Wake up a specific lockvoker + * @param lockvoker The lockvoker to wake up + */ + void wakeUp(LockerAndInvoker &lockvoker) + { + // TODO: Implement wake-up logic + // - Post the lockvoker's invocation to its io_service + // - This will cause the lockvoker to retry acquisition + (void)lockvoker; // Suppress unused parameter warning + } + +public: + SpinLock lock; + std::atomic isOwned; + LockerAndInvokerList queue; +}; + +} // namespace smo + +#endif // QUTEX_H