feat: add wasm-gc support for timer, event loop, and time

src/internal/event_loop/event_loop.js.mbt

@@ -28,7 +28,7 @@ pub fn reschedule() -> Unit {
   // Instead of looping blockingly until there is no ready task,
   // we only perform one round of scheduling here
   // (i.e., only those tasks already ready when `reschedule` is called are run).
-  // Remaining tasks are delayed untin the next js event loop,
+  // Remaining tasks are delayed until the next event loop iteration,
   // so that those blocking jobs got a chance to execute instead of starving.
   if @coroutine.has_immediately_ready_task() {
     ignore(set_timeout(0, reschedule))

src/internal/event_loop/moon.pkg

@@ -34,7 +34,7 @@ options(
   ],
   targets: {
     "cancel_before_submit_test.mbt": [ "native" ],
-    "event_loop.js.mbt": [ "js" ],
+    "event_loop.js.mbt": [ "js", "wasm-gc" ],
     "event_loop.mbt": [ "native" ],
     "fs.mbt": [ "native" ],
     "io.mbt": [ "native" ],
@@ -49,8 +49,9 @@ options(
     "process_windows.mbt": [ "native" ],
     "stdio.mbt": [ "native" ],
     "thread_pool.mbt": [ "native" ],
+    "timer.js.mbt": [ "js", "wasm-gc" ],
     "timer.mbt": [ "native" ],
-    "unimplemented.mbt": [ "wasm", "wasm-gc" ],
+    "unimplemented.mbt": [ "wasm" ],
     "worker_wbtest.mbt": [ "native", "js" ],
   },
 )

src/internal/event_loop/timer.js.mbt

@@ -17,9 +17,14 @@
 type Timer
 
 ///|
+#cfg(target="js")
 extern "js" fn set_timeout(duration : Int, f : () -> Unit) -> Timer =
   #| (duration, f) => setTimeout(f, duration)
 
+///|
+#cfg(target="wasm-gc")
+fn set_timeout(duration : Int, f : () -> Unit) -> Timer = "moonbitlang_async_timer" "setTimeout"
+
 ///|
 pub fn Timer::new(duration : Int, f : () -> Unit) -> Timer {
   set_timeout(duration, () => {
@@ -29,5 +34,16 @@ pub fn Timer::new(duration : Int, f : () -> Unit) -> Timer {
 }
 
 ///|
+#cfg(target="js")
 pub extern "js" fn Timer::cancel(self : Timer) =
   #| (timer) => clearTimeout(timer)
+
+///|
+#cfg(target="wasm-gc")
+fn clear_timeout(timer : Timer) = "moonbitlang_async_timer" "clearTimeout"
+
+///|
+#cfg(target="wasm-gc")
+pub fn Timer::cancel(self : Timer) -> Unit {
+  clear_timeout(self)
+}

src/internal/event_loop/wasm-gc-imports.js

@@ -0,0 +1,15 @@
+// Import objects for moonbitlang/async wasm-gc timer, event loop, and time modules.
+// When loading the compiled wasm-gc module, merge these into the import object:
+//
+//   import { moonbitlang_async_timer, moonbitlang_async_time } from "./wasm-gc-imports.js";
+//   const imports = { ...otherImports, moonbitlang_async_timer, moonbitlang_async_time };
+//   const { instance } = await WebAssembly.instantiateStreaming(fetch("module.wasm"), imports);
+
+export const moonbitlang_async_timer = {
+  setTimeout: (duration, f) => setTimeout(f, duration),
+  clearTimeout: (timer) => clearTimeout(timer),
+};
+
+export const moonbitlang_async_time = {
+  date_now: () => Date.now(),
+};

src/internal/time/time.mbt

@@ -62,7 +62,34 @@ pub fn ms_since_epoch() -> Int64 {
 }
 
 ///|
-#cfg(any(target="wasm", target="wasm-gc"))
+#cfg(target="wasm-gc")
+fn wasm_gc_date_now() -> Double = "moonbitlang_async_time" "date_now"
+
+///|
+/// Get the current wall-clock time in milliseconds.
+///
+/// This is the time source used by the async runtime. It is intended for
+/// computing elapsed time by subtraction. The value can jump forwards or
+/// backwards if the system clock is adjusted, so do not assume monotonicity.
+///
+/// Platform notes:
+/// - Unix/macOS: `gettimeofday()` (Unix epoch)
+/// - Windows: `GetSystemTimeAsFileTime()` (FILETIME epoch, 1601)
+/// - JavaScript/wasm-gc: `Date.now()` (Unix epoch)
+///
+/// # Example
+/// ```mbt check
+/// test {
+///   let _ : Int64 = ms_since_epoch()
+/// }
+/// ```
+#cfg(target="wasm-gc")
+pub fn ms_since_epoch() -> Int64 {
+  wasm_gc_date_now().to_int64()
+}
+
+///|
+#cfg(target="wasm")
 pub fn ms_since_epoch() -> Int64 {
   abort("unimplemented")
 }