/// <summary>
/// Can be disposed from any thread
/// </summary>
/// <returns></returns>
public async Task <IDisposable> LockWriteAsync(int millisecondsTimeout = int.MaxValue)
{
MyLockQueueItem queueItem;
IDisposable answer;
lock (_lock)
{
// If there's no items
if (_queue.Count == 0)
{
// Create a new write entry
var newEntry = new MyWriteLockQueueItem(this, true);
// Add it to the queue
_queue.Add(newEntry);
// We're already locked, so just return instantly
return(new MyDisposableLock(newEntry));
}
// Otherwise, we always just add for write locks
else
{
var newEntry = new MyWriteLockQueueItem(this, alreadyLocked: false);
_queue.Add(newEntry);
queueItem = newEntry;
answer = new MyDisposableLock(newEntry);
}
}
try
{
await TimeoutTask.Create(queueItem.LockedTask, millisecondsTimeout);
}
catch (TimeoutException)
{
queueItem.Release();
throw new TimeoutException("Timeout exceeded and lock not established.");
}
return(answer);
}
/// <summary>
/// Can be disposed from any thread
/// </summary>
/// <returns></returns>
public async Task <IDisposable> LockReadAsync(int millisecondsTimeout = int.MaxValue)
{
MyLockQueueItem queueItem;
IDisposable answer;
lock (_lock)
{
// If there's no items
if (_queue.Count == 0)
{
// Create a new read entry
var newEntry = new MyReadLockQueueItem(this, true);
// Add it to the queue
_queue.Add(newEntry);
// We're already locked, so just return instantly
return(new MyDisposableLock(newEntry));
}
// If there's only one item, and it's another read, merge with it
if (_queue.Count == 1 && _queue[0] is MyReadLockQueueItem)
{
(_queue[0] as MyReadLockQueueItem).Add();
// We're already locked, so just return instantly
return(new MyDisposableLock(_queue[0]));
}
// If there's a read at the end, merge with it
else if (_queue.Last() is MyReadLockQueueItem)
{
var last = _queue.Last() as MyReadLockQueueItem;
last.Add();
// Need to wait till this one starts
queueItem = last;
answer = new MyDisposableLock(last);
}
// Otherwise, the last item is a write, so we need to add new and wait
else
{
var newEntry = new MyReadLockQueueItem(this, alreadyLocked: false);
_queue.Add(newEntry);
queueItem = newEntry;
answer = new MyDisposableLock(newEntry);
}
}
try
{
await TimeoutTask.Create(queueItem.LockedTask, millisecondsTimeout);
}
catch (TimeoutException)
{
queueItem.Release();
throw new TimeoutException("Timeout exceeded and lock not established.");
}
return(answer);
}
