public async Task<bool> TryLockAsync(
LockToken token,
int tries = 16, // this is NOT retry - it is try
int retryTimeoutMilliseconds = 15000,
int timeoutMilliseconds = 15000)
{
if (tries < 1)
tries = 1;
var blob = await GetBlobAsync(token.ResourceId);
for (int i = 0; i < tries; i++)
{
try
{
await blob.AcquireLeaseAsync(
TimeSpan.FromMilliseconds(timeoutMilliseconds),
token.TokenId.ToString("N"));
return true;
}
catch (Exception e)
{
Trace.TraceInformation("Lock attempt - already locked: {0}", e);
// ignore
}
await Task.Delay(TimeSpan.FromMilliseconds(retryTimeoutMilliseconds / tries));
}
return false;
}
public async Task IncrementAsync(string counterName, string id, long value)
{
var key = string.Format("____COUNTER____{0}-{1}", counterName, id);
var token = new LockToken(key);
var result = await _lockStore.TryLockAsync(token);
if(!result)
throw new TimeoutException("Could not lock the resource");
var blob = await GetBlobAsync(key);
var text = await blob.DownloadTextAsync();
var current = long.Parse(string.IsNullOrEmpty(text) ? "0" : text);
var newValue = current + value;
if(newValue < 0)
throw new InvalidOperationException("Value cannot get below zero: " + newValue);
await blob.UploadTextAsync(newValue.ToString());
await _lockStore.ReleaseLockAsync(token);
}
public void TwoCannotLockAtTheSameTime()
{
var locker = new AzureLockStore(
new BlobSource()
{
ContainerName = "band25",
ConnectionString = ConnectionString,
Path = "this/is/great/"
});
var resource = Guid.NewGuid().ToString();
var token = new LockToken(resource);
var canLock = locker.TryLockAsync(token).Result;
Assert.True(canLock);
var newtoken = new LockToken(resource);
var canDoubleLock = locker.TryLockAsync(newtoken,
1, 100).Result;
Assert.False(canDoubleLock);
}
public async Task<Tuple<IEnumerable<Event>, bool>> TryScheduleAsync(DiagnosticsSource source)
{
// if Stop offset has been reached
if (source.StopOffsetPoint != null && source.LastOffsetPoint != null && source.LastOffsetPoint.CompareTo(source.StopOffsetPoint) >= 0)
return new Tuple<IEnumerable<Event>, bool>(Enumerable.Empty<Event>(), false);
var lockToken = new LockToken(source.ToTypeKey());
int seconds =
Convert.ToInt32(_configurationValueProvider.GetValue(ConfigurationKeys.ClusterLockDurationSeconds));
if (!(await _lockStore.TryLockAsync(lockToken, 2, 1000, seconds * 1000)))
{
TheTrace.TraceInformation("I could NOT be master for {0}", source.ToTypeKey());
return new Tuple<IEnumerable<Event>, bool>(Enumerable.Empty<Event>(), false);
}
try
{
var events = await DoSchedule(source);
return new Tuple<IEnumerable<Event>, bool>(events, true);
}
finally
{
Task.Run( () => _lockStore.ReleaseLockAsync(lockToken)).Wait();
}
}
public async Task ReleaseLockAsync(LockToken token)
{
var blob = await GetBlobAsync(token.ResourceId);
await blob.ReleaseLeaseAsync(AccessCondition.GenerateLeaseCondition(token.TokenId.ToString("N")));
}