private async Task StartInternalAsync(
string lockName,
LockLostBehavior lockLostBehavior,
CancellationToken cancellationToken)
{
_log.TraceMethodEntry();
if (cancellationToken.IsCancellationRequested)
{
return;
}
var lockTimeout = TimeSpan.FromSeconds(5);
using (var inMemoryLockCacheClient = new InMemoryCacheClient())
using (var distributedLockCacheClient = new HybridCacheClient(inMemoryLockCacheClient, _messageBus))
{
var lockProvider = new CacheLockProvider(distributedLockCacheClient, _messageBus);
while (!cancellationToken.IsCancellationRequested)
{
var lockHandle = await lockProvider.AcquireAsync(
lockName,
lockTimeout,
cancellationToken)
.ConfigureAwait(false);
if (lockHandle != null)
{
try
{
// we have the lock
// keep renewing it
await HoldAndRenewAsync(
lockHandle,
cancellationToken)
.ConfigureAwait(false);
}
catch (Exception e)
{
switch (lockLostBehavior)
{
case LockLostBehavior.Complete:
return;
case LockLostBehavior.Error:
throw new LockLostException(lockName, e);
case LockLostBehavior.Retry:
break;
default:
break;
}
}
}
}
}
}
/// <summary>
/// Creates and starts a Distributed Lock Process Manager.
/// </summary>
/// <param name="messageBus">The message bus to attach to.</param>
/// <param name="loggerFactory">The logging interface factory.</param>
/// <param name="lockName">The name of the lock.</param>
/// <param name="lockLostBehavior">The behavior to carry out if the lock is lost.</param>
/// <param name="hasLockObserver">The observer for watching if the lock is aquired.</param>
/// <param name="cancellationToken">The cancellation token used to stop the process manager.</param>
/// <returns>Instance of the distributed lock process manager and the active task.</returns>
public static (DistributedLockProcessManager Instance, Task Task, IDisposable HasLockSubscription) SubscribeAndStart(
IMessageBus messageBus,
ILoggerFactory loggerFactory,
string lockName,
LockLostBehavior lockLostBehavior,
IObserver <bool> hasLockObserver,
CancellationToken cancellationToken)
{
if (hasLockObserver == null)
{
throw new ArgumentNullException(nameof(hasLockObserver));
}
var instance = new DistributedLockProcessManager(
messageBus,
lockName,
lockLostBehavior,
loggerFactory);
var hasLockSubscription = instance.HasLock.Subscribe(hasLockObserver);
var task = instance.StartAsync(cancellationToken);
return(instance, task, hasLockSubscription);
}
/// <summary>
/// Initializes a new instance of the <see cref="DistributedLockProcessManager"/> class.
/// </summary>
/// <param name="messageBus">The message bus to attach to.</param>
/// <param name="lockName">The name of the lock.</param>
/// <param name="lockLostBehavior">The behavior to carry out if the lock is lost.</param>
/// <param name="loggerFactory">The logging interface factory.</param>
public DistributedLockProcessManager(
IMessageBus messageBus,
string lockName,
LockLostBehavior lockLostBehavior,
ILoggerFactory loggerFactory)
{
_messageBus = messageBus ?? throw new ArgumentNullException(nameof(messageBus));
if (string.IsNullOrWhiteSpace(lockName))
{
throw new ArgumentNullException(nameof(lockName));
}
_lockName = lockName;
_lockLostBehaviour = lockLostBehavior;
if (loggerFactory == null)
{
throw new ArgumentNullException(nameof(loggerFactory));
}
_log = loggerFactory.CreateLogger <DistributedLockProcessManager>();
}