Implement async event streaming

Sources/Inotify/Inotify.swift

@@ -1,14 +1,21 @@
+import Dispatch
 import CInotify
 
 public actor Inotify {
 	private let fd: Int32
 	private var watches: [Int32: String] = [:]
+	private var eventReader: any DispatchSourceRead
+	private var eventStream: AsyncStream<RawInotifyEvent>
+	public var events: AsyncCompactMapSequence<AsyncStream<RawInotifyEvent>, InotifyEvent> {
+		self.eventStream.compactMap(self.transform(_:))
+	}
 
 	public init() throws {
 		self.fd = inotify_init1(Int32(IN_NONBLOCK | IN_CLOEXEC))
 		guard self.fd >= 0 else {
 			throw InotifyError.initFailed(errno: cinotify_get_errno())
 		}
+		(self.eventReader, self.eventStream) = Self.createEventReader(forFileDescriptor: fd)
 	}
 
 	@discardableResult
@@ -31,4 +38,33 @@ public actor Inotify {
 	deinit {
 		cinotify_deinit(self.fd)
 	}
+
+	private func transform(_ rawEvent: RawInotifyEvent) -> InotifyEvent? {
+		guard let path = self.watches[rawEvent.watchDescriptor] else { return nil }
+		return InotifyEvent.init(from: rawEvent, inDirectory: path)
+	}
+
+	private static func createEventReader(forFileDescriptor fd: Int32) -> (any DispatchSourceRead, AsyncStream<RawInotifyEvent>) {
+		let (stream, continuation) = AsyncStream<RawInotifyEvent>.makeStream(
+			of: RawInotifyEvent.self,
+			bufferingPolicy: .bufferingNewest(512)
+		)
+
+		let reader = DispatchSource.makeReadSource(
+			fileDescriptor: fd,
+			queue: DispatchQueue(label: "Inotify.read", qos: .utility)
+		)
+
+		reader.setEventHandler {
+			for rawEvent in InotifyEventParser.parse(fromFileDescriptor: fd) {
+				continuation.yield(rawEvent)
+			}
+		}
+		reader.setCancelHandler {
+			continuation.finish()
+		}
+		reader.activate()
+
+		return (reader, stream)
+	}
 }