Initial project import

tools/v/vlib/x/async/async.v

@@ -0,0 +1,35 @@
+module async
+
+import context
+
+// JobFn is the function signature run by Group and timeout helpers.
+//
+// The passed context is canceled when the parent context is canceled, when a
+// group task fails, or when a timeout expires. Cancellation is cooperative:
+// jobs should observe `ctx.done()` and return.
+pub type JobFn = fn (mut context.Context) !
+
+// TaskFn is the function signature run by Task.
+//
+// It mirrors JobFn but returns a value. Like all x.async work, the function
+// receives a context and must observe `ctx.done()` for cooperative cancellation.
+pub type TaskFn[T] = fn (mut context.Context) !T
+
+// background returns a root context for async helpers.
+//
+// It is intentionally just a thin wrapper around `context.background()` so code
+// can start with `async.background()` and later pass the same context to the
+// standard `context` APIs without conversion.
+pub fn background() context.Context {
+	return context.background()
+}
+
+// with_cancel returns a cancellable context derived from background.
+//
+// Call the returned cancel function when the surrounding operation is done, even
+// when all jobs completed successfully. That mirrors `context.with_cancel()` and
+// releases parent/child cancellation references promptly.
+pub fn with_cancel() (context.Context, context.CancelFn) {
+	ctx, cancel := new_cancel_context(context.background())
+	return context.Context(ctx), cancel
+}