Initial commit of libspinscale library

include/spinscale/qutex.h

@@ -0,0 +1,107 @@
+#ifndef QUTEX_H
+#define QUTEX_H
+
+#include <config.h>
+#include <list>
+#include <memory>
+#include <string>
+#include <spinscale/spinLock.h>
+#include <spinscale/lockerAndInvokerBase.h>
+
+namespace sscl {
+
+/**
+ * @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:
+	/**
+	 * @brief Constructor
+	 */
+	Qutex([[maybe_unused]] const std::string &_name)
+	:
+#ifdef CONFIG_ENABLE_DEBUG_LOCKS
+	name(_name), currOwner(nullptr),
+#endif
+	isOwned(false)
+	{}
+
+	/**
+	 * @brief Register a lockvoker in the queue
+	 * @param lockvoker The lockvoker to register
+	 * @return Iterator pointing to the registered lockvoker in the queue
+	 */
+	LockerAndInvokerBase::List::iterator registerInQueue(
+		const std::shared_ptr<LockerAndInvokerBase> &lockvoker
+		)
+	{
+		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
+	 * @param shouldLock Whether to acquire the spinlock before erasing (default: true)
+	 */
+	void unregisterFromQueue(
+		LockerAndInvokerBase::List::iterator it, bool shouldLock = true
+		)
+	{
+		if (shouldLock)
+		{
+			lock.acquire();
+			queue.erase(it);
+			lock.release();
+		}
+		else {
+			queue.erase(it);
+		}
+	}
+
+	/**
+	 * @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(
+		const LockerAndInvokerBase &tryingLockvoker, int nRequiredLocks);
+
+	/**
+	 * @brief Handle backoff when a lockvoker fails to acquire all required locks
+	 * @param failedAcquirer The lockvoker that failed to acquire all locks
+	 * @param nRequiredLocks Number of locks required by the lockvoker's LockSet
+	 */
+	void backoff(const LockerAndInvokerBase &failedAcquirer, int nRequiredLocks);
+
+	/**
+	 * @brief Release the lock and wake up the next waiting lockvoker
+	 */
+	void release();
+
+#ifdef CONFIG_ENABLE_DEBUG_LOCKS
+	std::shared_ptr<LockerAndInvokerBase> getCurrOwner() const
+		{ return currOwner; }
+#endif
+
+public:
+#ifdef CONFIG_ENABLE_DEBUG_LOCKS
+	std::string name;
+	std::shared_ptr<LockerAndInvokerBase> currOwner;
+#endif
+	SpinLock lock;
+	LockerAndInvokerBase::List queue;
+	bool isOwned;
+};
+
+} // namespace sscl
+
+#endif // QUTEX_H