/// <summary>
/// Attempts to pass an error to the router and return whether or not it should be removed.
/// </summary>
/// <param name="router"></param>
/// <param name="exception"></param>
/// <param name="cancellationToken"></param>
/// <returns></returns>
async ValueTask TryAbortRouter(FrameRouter router, Exception exception, CancellationToken cancellationToken)
{
try
{
await router.AbortAsync(exception, cancellationToken);
}
catch (Exception e)
{
logger.LogError(e, "Unhandled exception occurred dispatching exception to listener.");
}
}
/// <summary>
/// Attempts to execute the listener and return whether or not it should be removed. If the listener throws an exception, it is logged and marked for removal.
/// </summary>
/// <param name="router"></param>
/// <param name="frame"></param>
/// <param name="cancellationToken"></param>
/// <returns></returns>
async ValueTask <bool> TryRouteAsync(FrameRouter router, StompFrame frame, CancellationToken cancellationToken)
{
try
{
return(await router.RouteAsync(frame, cancellationToken));
}
catch (Exception e)
{
logger.LogError(e, "Unhandled exception occurred dispatching frame to trigger.");
return(false);
}
}
/// <summary>
/// Sends the specified frame, and registers a completion for the next frame that matches the specified conditions.
/// </summary>
/// <param name="command"></param>
/// <param name="headers"></param>
/// <param name="body"></param>
/// <param name="response"></param>
/// <param name="cancellationToken"></param>
/// <returns></returns>
async ValueTask <StompFrame> SendFrameAndWaitAsync(StompCommand command, IEnumerable <KeyValuePair <string, string> > headers, ReadOnlyMemory <byte> body, Func <StompFrame, bool> response, CancellationToken cancellationToken)
{
headers ??= Enumerable.Empty <KeyValuePair <string, string> >();
// schedule a router for the frame filter
var tcs = new TaskCompletionSource <StompFrame>();
ValueTask <bool> WriteAsync(StompFrame frame, CancellationToken cancellationToken)
{
tcs.SetResult(frame); return(new ValueTask <bool>(false));
}
ValueTask AbortAsync(Exception exception, CancellationToken cancellationToken)
{
tcs.SetException(exception); return(ValueTaskHelper.CompletedTask);
}
var hnd = new FrameRouter(response, WriteAsync, AbortAsync);
// handle cancellation through new task
cancellationToken.Register(() => tcs.TrySetCanceled(cancellationToken));
// subscribe to matching frames
var node = await RegisterRouterAsync(hnd, cancellationToken);
try
{
// send initial frame and wait for resumption
await SendFrameAsync(new StompFrame(command, headers, body), cancellationToken);
return(await tcs.Task);
}
finally
{
// ensure listener is removed upon completion
if (node.List != null)
{
using (await routersLock.LockAsync())
if (node.List != null)
{
routers.Remove(node);
}
}
}
}
/// <summary>
/// Registers a trigger for a frame condition.
/// </summary>
/// <param name="trigger"></param>
/// <param name="cancellationToken"></param>
/// <returns></returns>
async ValueTask <LinkedListNode <FrameRouter> > RegisterRouterAsync(FrameRouter trigger, CancellationToken cancellationToken)
{
using (await routersLock.LockAsync(cancellationToken))
return(routers.AddLast(trigger));
}
