public EnterLock(IDbFactory db, IIntegrationDatabaseConfiguration configuration, DistributedMutexContext context, TimeSpan queryLockInterval, CancellationToken cancellationToken)
{
_db = db;
_configuration = configuration;
_newLock = new DbDistributedMutexLock(context.Name)
{
MachineName = Environment.MachineName,
Description = context.Description.MaxLength(255)
};
using (IDbSession session = db.OpenSession())
{
TimeSpan waitTime = context.WaitTime;
int maxRetries = Math.Max((int)Math.Ceiling(waitTime.TotalMilliseconds / queryLockInterval.TotalMilliseconds), 1);
int attempts = 0;
DbDistributedMutexLock currentLock;
while (true)
{
if (TryEnterLock(session, out currentLock))
{
_onCancel = cancellationToken.Register(ReleaseLock);
return;
}
if (currentLock == null)
{
throw new InvalidOperationException($"Cannot obtain lock for '{_newLock.Name}', but current lock is null.");
}
if (++attempts >= maxRetries)
{
break;
}
context.OnWaiting($"{currentLock}. Waiting for {queryLockInterval} (attemt {attempts} of {maxRetries}).");
cancellationToken.WaitHandle.WaitOne(queryLockInterval);
}
throw new DistributedMutexTimeoutException($"Unable to acquire lock '{_newLock.Name}' within wait time ({waitTime}) using {attempts} attempts with a query interval of {queryLockInterval}. {currentLock}");
}
}
private bool TryEnterLock(IDbSession session, out DbDistributedMutexLock currentLock)
{
currentLock = session.Query <DbDistributedMutexLock>($@"
BEGIN TRY
INSERT INTO [{_configuration.TableName(IntegrationDbTable.DistributedMutex)}] (Name, LockId, CreatedAt, MachineName, Description)
VALUES (@Name, @LockId, @CreatedAt, @MachineName, @Description)
END TRY
BEGIN CATCH
DECLARE @ErrorNumber AS INT
SELECT @ErrorNumber = ERROR_NUMBER();
IF @ErrorNumber = 2627 -- PRIMARY KEY VIOLATION
SELECT * FROM [{_configuration.TableName(IntegrationDbTable.DistributedMutex)}] WHERE (Name = @Name);
ELSE
THROW
END CATCH",
_newLock).FirstOrDefault();
return(currentLock == null);
}
