public bool TryAcquireLockEntry(InMemoryConnection connection, string resource, out LockEntry entry)
{
var acquired = false;
lock (_state._locks)
{
if (!_state._locks.TryGetValue(resource, out entry))
{
_state._locks.Add(resource, entry = new LockEntry {
Owner = connection, ReferenceCount = 1, Level = 1
});
acquired = true;
}
else if (entry.Owner == connection)
{
entry.Level++;
acquired = true;
}
// TODO: Ensure ReferenceCount is updated only under _state._locks
entry.ReferenceCount++;
}
return(acquired);
}
public LockDisposable(InMemoryDispatcherBase dispatcher, InMemoryConnection reference, string resource, LockEntry entry)
{
_dispatcher = dispatcher;
_reference = reference;
_resource = resource;
_entry = entry ?? throw new ArgumentNullException(nameof(entry));
}
public void CancelLockEntry(string resource, LockEntry entry)
{
lock (_state._locks)
{
if (!_state._locks.TryGetValue(resource, out var current2) || !ReferenceEquals(current2, entry))
{
throw new InvalidOperationException("Precondition failed when decrementing a lock");
}
entry.ReferenceCount--;
if (entry.ReferenceCount == 0)
{
_state._locks.Remove(resource);
}
}
}
public void ReleaseLockEntry(InMemoryConnection connection, string resource, LockEntry entry)
{
// TODO: Ensure lock ordering to avoid deadlocks
lock (_state._locks)
{
if (!_state._locks.TryGetValue(resource, out var current))
{
throw new InvalidOperationException("Does not contain a lock");
}
if (!ReferenceEquals(current, entry))
{
throw new InvalidOperationException("Does not contain a correct lock entry");
}
lock (entry)
{
if (!ReferenceEquals(entry.Owner, connection))
{
throw new InvalidOperationException("Wrong entry owner");
}
if (entry.Level <= 0)
{
throw new InvalidOperationException("Wrong level");
}
entry.Level--;
if (entry.Level == 0)
{
entry.Owner = null;
entry.ReferenceCount--;
if (entry.ReferenceCount == 0)
{
_state._locks.Remove(resource);
}
else
{
Monitor.Pulse(entry);
}
}
}
}
}