internal static SessionSemaphore ObtainCrossServerLock(HttpSessionState session, string sessionKey)
{
SessionSemaphore semaphore = null;
var identity = Guid.NewGuid().ToString("N"); //compute identity before locking
string semaphoreKey = SEMAPHORE_PREFIX + sessionKey; //compute key before locking
lock (_singleServerLocks.GetOrAdd(sessionKey, new object())) //one thread per server per session key will pass beyond this point
{
do
{
while (session[semaphoreKey] != null)
{
Thread.Sleep(1);
}
session[semaphoreKey] = identity;
Thread.Sleep(1);
if (session[semaphoreKey].ToString() == identity)
{
semaphore = new SessionSemaphore(identity, semaphoreKey, session);
}
} while (semaphore == null);
}
return(semaphore);
}
public static SessionSemaphore ObtainCrossServerLock(this HttpSessionState session, string sessionKey)
{
return(SessionSemaphore.ObtainCrossServerLock(session, sessionKey));
}