protected override async Task <Tuple <bool, JObject> > TryObtainLockAsync(string lockMessage, CancellationToken token)
{
// Create the feedlock file if it doesn't exist, this will stay around indefinitely. The lock is done
// by leasing this file.
await CreateFileIfNotExistsAsync();
// Try to lease the blob
var result = await _lease.GetLease();
if (result)
{
// Keep the lease
if (_keepLockTask == null)
{
_keepLockTask = Task.Run(async() => await KeepLock());
}
// For azure blobs the message goes into a separate file.
var json = GetMessageJson(lockMessage);
_updateLockMessage = _messageBlob.UploadTextAsync(json.ToString());
// The message is not needed for success
return(Tuple.Create(result, new JObject()));
}
else
{
// Return a non-successful result along with the message from the other client locking this feed if one exists.
var json = await GetMessageJson();
return(Tuple.Create(result, json));
}
}
public async Task <bool> GetLock(TimeSpan wait, CancellationToken token)
{
var result = false;
if (!_isLocked)
{
var exists = await _blob.ExistsAsync();
if (!exists)
{
// Create the feed lock blob if it doesn't exist
var bytes = Encoding.UTF8.GetBytes("feedlock");
await _blob.UploadFromByteArrayAsync(bytes, 0, bytes.Length);
}
var timer = new Stopwatch();
timer.Start();
var lastNotify = TimeSpan.Zero;
var firstLoop = true;
do
{
result = await _lease.GetLease();
if (!result)
{
var diff = timer.Elapsed.Subtract(lastNotify);
if (diff.TotalSeconds > 60 || firstLoop)
{
_log.LogMinimal($"Waiting to obtain an exclusive lock on the feed.");
}
firstLoop = false;
await Task.Delay(100);
}
}while (!result && timer.Elapsed < wait);
if (!result)
{
_log.LogError($"Unable to obtain a lock on the feed. Try again later.");
}
else if (_keepLockTask == null)
{
_keepLockTask = Task.Run(async() => await KeepLock());
}
_isLocked = result;
}
return(result);
}