dispatch the applicable handlers for an event
(event: Event<any, TResult>)
| 56 | |
| 57 | /** dispatch the applicable handlers for an event */ |
| 58 | async function dispatch<TResult>(event: Event<any, TResult>): Promise<void> { |
| 59 | // check the sync handlers first |
| 60 | let resultValue: EventStatus | TResult | undefined = Continue; |
| 61 | |
| 62 | // sync handlers run and await one at a time |
| 63 | // technically, it's possible for other events to run while a sync handler is running |
| 64 | // but that doesn't make any difference; the sync handler will still run to completion |
| 65 | // before the next handler is dispatched. |
| 66 | for (const [callback, captures] of getHandlers(event, syncHandlers)) { |
| 67 | try { |
| 68 | // keep track of which handlers are currently running |
| 69 | current.add(callback); |
| 70 | |
| 71 | // call the callback, collate the result. |
| 72 | let r = callback(event as EventData, ...captures); |
| 73 | r = is.promise(r) ? await r.catch(e => { |
| 74 | console.error(e); |
| 75 | return undefined; |
| 76 | }) : r; |
| 77 | |
| 78 | // if it is an event/request (as opposed to a notification), then process it. |
| 79 | if (is.promise(event.completed)) { |
| 80 | // if they returned some kind of value, then use that as the result, otherwise, use the default |
| 81 | resultValue = r as TResult | EventStatus; |
| 82 | |
| 83 | if (is.cancelled(resultValue)) { |
| 84 | return event.completed.resolve(resultValue); // the event has been cancelled |
| 85 | } |
| 86 | } |
| 87 | } catch (e: any) { |
| 88 | console.error(e); |
| 89 | // if the handler throws, it isn't a reason to cancel the event |
| 90 | } finally { |
| 91 | // clear the callback from the current set |
| 92 | current.delete(callback); |
| 93 | } |
| 94 | } |
| 95 | |
| 96 | // then the async handlers (for events with possible result handling) |
| 97 | |
| 98 | if (!is.promise(event.completed)) { |
| 99 | // no event.completed, which means this is a notifier |
| 100 | // since notifiers are not cancellable, we can run them all in parallel |
| 101 | // and they don't need to worry about reentrancy |
| 102 | for (const [callback, captures] of getHandlers(event, asyncHandlers)) { |
| 103 | // call the event handler, but don't await it |
| 104 | // we don't care about the result, and we don't want to block |
| 105 | // (if the handler throws, too bad) |
| 106 | try { void callback(event as EventData, ...captures); } catch (e: any) { |
| 107 | console.error(e); |
| 108 | /* ignore */ |
| 109 | } |
| 110 | } |
| 111 | return; |
| 112 | } |
| 113 | // this is an event/request (supports a result or cancellation) |
| 114 | // when these are called, they are permitted to work in parallel, and we await them all at the end |
| 115 | // the first one to respond with a non-Continue result will be the result of the event |