// CAUTION - we disable the Obsolte warning for this extension method
// IDistributedLockManager is marked as obsolete, but not because it will
// go away in the near term. The webjob SDK marked it with the comment
// that the current implementation is not ready for public use. however
// as the Azure Functions framework already relies on it, we assume it
// is also good enought for our scenarios.
#pragma warning disable CS0618
public static async Task <IDistributedLock> AcquireLockAsync(this IDistributedLockManager distributedLockManager, string lockId, string lockOwner, TimeSpan?lockPeriod = default, TimeSpan?acquisitionTimeout = default, CancellationToken cancellationToken = default)
{
if (distributedLockManager is null)
{
throw new ArgumentNullException(nameof(distributedLockManager));
}
if (string.IsNullOrEmpty(lockId))
{
throw new ArgumentException($"'{nameof(lockId)}' cannot be null or empty", nameof(lockId));
}
if (string.IsNullOrEmpty(lockOwner))
{
throw new ArgumentException($"'{nameof(lockOwner)}' cannot be null or empty", nameof(lockOwner));
}
using var acquisitionCancellationTokenSource = new CancellationTokenSource(acquisitionTimeout.GetValueOrDefault(TimeSpan.FromMinutes(1)));
using var linkedCancellationTokenSource = CancellationTokenSource.CreateLinkedTokenSource(acquisitionCancellationTokenSource.Token, cancellationToken);
while (!linkedCancellationTokenSource.Token.IsCancellationRequested)
{
var distributedLock = await distributedLockManager
.TryLockAsync(null, lockId, lockOwner, null, lockPeriod.GetValueOrDefault(TimeSpan.FromMinutes(1)), linkedCancellationTokenSource.Token)
.ConfigureAwait(false);
if (distributedLock != null)
{
return(distributedLock);
}
}
throw new TimeoutException($"Unable to acquire lock {lockId} for owner {lockOwner}");
}
private async Task AcquireOrRenewLeaseAsync()
{
if (_hostId == null)
{
_hostId = await _hostIdProvider.GetHostIdAsync(CancellationToken.None);
}
string lockName = GetBlobName(_hostId);
DateTime requestStart = DateTime.UtcNow;
if (HasLease)
{
try
{
await _lockManager.RenewAsync(LockHandle, CancellationToken.None);
_lastRenewal = DateTime.UtcNow;
_lastRenewalLatency = _lastRenewal - requestStart;
}
catch
{
// The lease was 'stolen'. Log details for debugging.
string lastRenewalFormatted = _lastRenewal.ToString("yyyy-MM-ddTHH:mm:ss.FFFZ", CultureInfo.InvariantCulture);
int millisecondsSinceLastSuccess = (int)(DateTime.UtcNow - _lastRenewal).TotalMilliseconds;
int lastRenewalMilliseconds = (int)_lastRenewalLatency.TotalMilliseconds;
ProcessLeaseError($"Another host has acquired the lease. The last successful renewal completed at {lastRenewalFormatted} ({millisecondsSinceLastSuccess} milliseconds ago) with a duration of {lastRenewalMilliseconds} milliseconds.");
}
}
else
{
string proposedLeaseId = _websiteInstanceId;
LockHandle = await _lockManager.TryLockAsync(null, lockName, _websiteInstanceId, proposedLeaseId, _leaseTimeout, CancellationToken.None);
if (LockHandle == null)
{
// We didn't have the lease and failed to acquire it. Common if somebody else already has it.
// This is normal and does not warrant any logging.
return;
}
_lastRenewal = DateTime.UtcNow;
_lastRenewalLatency = _lastRenewal - requestStart;
string message = $"Host lock lease acquired by instance ID '{_websiteInstanceId}'.";
_logger.LogInformation(message);
// We've successfully acquired the lease, change the timer to use our renewal interval
SetTimerInterval(_renewalInterval);
}
}