public Task <TenantShell <TTenant> > Get(TenantIdentifier identifier)
{
return(Task.Run(() =>
{
return _factory(identifier);
}));
}
public async Task <TenantShell <TTenant> > ResolveTenantShell(TenantIdentifier identifier, ITenantShellFactory <TTenant> tenantFactory)
{
if (_cache.TryGetValue(identifier, out TenantShell <TTenant> result))
{
return(result);
}
try
{
await _semaphore.WaitAsync();
// Double locking - check cache again incase another thread just put it there.
if (_cache.TryGetValue(identifier, out result))
{
return(result);
}
// initialise tenant shell for tenant identifier.
var tenantResult = await tenantFactory.Get(identifier);
if (tenantResult == null)
{
// don't cache / associate null tenant shells with tenant identifiers. This means future requests for a tenant who currenlty has a null shell will contiue to flow throw to the factory
// until it returns a tenant shell result.
// This is better flow if you are creating new tenants dynamically and a request is recieved on the new tenants URL before the tenants has been set up in the source.
// It means the request will resolve to a null tenant shell for a while, (factory may keep returning null), and eventually when a tenant is actually returned from the factory, a new tenant shell will then be created and added to
// the cache, at which point the factory will stop being used for subsequent requests.
return(null);
}
// We got a new shell, so add it to the cache under its identifier, and any additional identifiers.
_cache.AddOrUpdate(identifier, tenantResult, (a, b) => { return(tenantResult); });
bool distinguisherFound = false;
foreach (var item in tenantResult.Identifiers)
{
if (item.Equals(identifier))
{
distinguisherFound = true;
continue;
}
_cache.AddOrUpdate(item, tenantResult, (a, b) => { return(tenantResult); });
}
if (!distinguisherFound)
{
tenantResult.Identifiers.Add(identifier);
}
return(tenantResult);
}
finally
{
_semaphore.Release();
}
}
public virtual Task <TenantIdentifier> IdentifyTenant()
{
TenantIdentifier identity = null;
var context = HttpContextAccessor.GetCurrent();
if (HttpContextAccessor != null)
{
identity = GetTenantDistinguisher(context);
}
return(Task.FromResult(identity));
}
public async Task <IDisposable> RemoveTenantShell(TenantIdentifier identifier)
{
TenantShell <TTenant> removed = null;
if (!_cache.TryGetValue(identifier, out TenantShell <TTenant> result))
{
// tenant hasn't yet been initialised.. so nothing to do..
return(null);
}
try
{
await _semaphore.WaitAsync(); // block restarting if a tenant intiialise in process or another restart in prcess.
// tenant may have just been restarted on another thread and removed from cache, so check again.
//Todo: make this more robust if TryRemove returns false for example..
var isRemoved = _cache.TryRemove(identifier, out removed);
if (isRemoved)
{
foreach (var item in removed.Identifiers)
{
if (item.Equals(identifier))
{
continue;
}
isRemoved = _cache.TryRemove(item, out TenantShell <TTenant> itemRemoved);
}
}
// dispose after small delay to allow respoinse to be returned flowing back through the same pipeline.
#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
return(removed);
//Task.Delay(new TimeSpan(0, 0, 2)).ContinueWith((t) =>
//{
// removed?.Dispose();
//});
#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
}
finally
{
_semaphore.Release();
}
}
public bool TryRemove(TenantIdentifier key, out TenantShell <TTenant> value)
{
return(_mappings.TryRemove(key, out value));
}
public TenantShell <TTenant> AddOrUpdate(TenantIdentifier key,
TenantShell <TTenant> addValue,
Func <TenantIdentifier, TenantShell <TTenant>, TenantShell <TTenant> > updateValueFactory)
{
return(_mappings.AddOrUpdate(key, addValue, updateValueFactory));
}