public async Task Invoke(HttpContext httpContext)
{
// Ensure all ShellContext are loaded and available.
await _shellHost.InitializeAsync();
var shellSettings = _runningShellTable.Match(httpContext);
// We only serve the next request if the tenant has been resolved.
if (shellSettings != null)
{
if (shellSettings.State == TenantState.Initializing)
{
httpContext.Response.Headers.Add(HeaderNames.RetryAfter, "10");
httpContext.Response.StatusCode = StatusCodes.Status503ServiceUnavailable;
await httpContext.Response.WriteAsync("The requested tenant is currently initializing.");
return;
}
// Makes 'RequestServices' aware of the current 'ShellScope'.
httpContext.UseShellScopeServices();
var shellScope = await _shellHost.GetScopeAsync(shellSettings);
// Holds the 'ShellContext' for the full request.
httpContext.Features.Set(new ShellContextFeature
{
ShellContext = shellScope.ShellContext,
OriginalPath = httpContext.Request.Path,
OriginalPathBase = httpContext.Request.PathBase
});
await shellScope.UsingAsync(scope => _next.Invoke(httpContext));
}
}
protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
stoppingToken.Register(() =>
{
_logger.LogInformation("'{ServiceName}' is stopping.", nameof(ModularBackgroundService));
});
if (_options.ShellWarmup)
{
// Ensure all ShellContext are loaded and available.
await _shellHost.InitializeAsync();
}
while (GetRunningShells().Count() < 1)
{
try
{
await Task.Delay(MinIdleTime, stoppingToken);
}
catch (TaskCanceledException)
{
break;
}
}
var previousShells = Enumerable.Empty <ShellContext>();
while (!stoppingToken.IsCancellationRequested)
{
try
{
var runningShells = GetRunningShells();
await UpdateAsync(previousShells, runningShells, stoppingToken);
previousShells = runningShells;
var pollingDelay = Task.Delay(PollingTime, stoppingToken);
await RunAsync(runningShells, stoppingToken);
await WaitAsync(pollingDelay, stoppingToken);
}
catch (Exception ex) when(!ex.IsFatal())
{
_logger.LogError(ex, "Error while executing '{ServiceName}'", nameof(ModularBackgroundService));
}
}
}
public async Task Invoke(HttpContext httpContext)
{
// Ensure all ShellContext are loaded and available.
await _shellHost.InitializeAsync();
var shellSettings = _runningShellTable.Match(httpContext);
// We only serve the next request if the tenant has been resolved.
if (shellSettings != null)
{
if (shellSettings.State == TenantState.Initializing)
{
httpContext.Response.Headers.Add(HeaderNames.RetryAfter, "10");
httpContext.Response.StatusCode = StatusCodes.Status503ServiceUnavailable;
await httpContext.Response.WriteAsync("The requested tenant is currently initializing.");
return;
}
var hasPendingTasks = false;
// We need to get a scope and the ShellContext that created it
var(scope, shellContext) = await _shellHost.GetScopeAndContextAsync(shellSettings);
using (scope)
{
// Register the shell context as a custom feature
httpContext.Features.Set(shellContext);
if (!shellContext.IsActivated)
{
var semaphore = _semaphores.GetOrAdd(shellSettings.Name, (name) => new SemaphoreSlim(1));
await semaphore.WaitAsync();
try
{
// The tenant gets activated here
if (!shellContext.IsActivated)
{
using (var activatingScope = await _shellHost.GetScopeAsync(shellSettings))
{
var tenantEvents = activatingScope.ServiceProvider.GetServices <IModularTenantEvents>();
foreach (var tenantEvent in tenantEvents)
{
await tenantEvent.ActivatingAsync();
}
foreach (var tenantEvent in tenantEvents.Reverse())
{
await tenantEvent.ActivatedAsync();
}
}
shellContext.IsActivated = true;
}
}
finally
{
semaphore.Release();
_semaphores.TryRemove(shellSettings.Name, out semaphore);
}
}
await _next.Invoke(httpContext);
var deferredTaskEngine = scope.ServiceProvider.GetService <IDeferredTaskEngine>();
hasPendingTasks = deferredTaskEngine?.HasPendingTasks ?? false;
}
// Create a new scope only if there are pending tasks
if (hasPendingTasks)
{
using (var pendingScope = await _shellHost.GetScopeAsync(shellSettings))
{
if (pendingScope != null)
{
var deferredTaskEngine = pendingScope.ServiceProvider.GetService <IDeferredTaskEngine>();
var context = new DeferredTaskContext(pendingScope.ServiceProvider);
await deferredTaskEngine.ExecuteTasksAsync(context);
}
}
}
}
}
