1 files changed, 51 insertions, 0 deletions
diff --git a/rts/win32/AwaitEvent.c b/rts/win32/AwaitEvent.c
new file mode 100644
index 0000000000..43e188fb34
--- /dev/null
+++ b/rts/win32/AwaitEvent.c
@@ -0,0 +1,51 @@
+#if !defined(THREADED_RTS) /* to the end */
+/*
+ * Wait/check for external events. Periodically, the
+ * Scheduler checks for the completion of external operations,
+ * like the expiration of timers, completion of I/O requests
+ * issued by Haskell threads.
+ *
+ * If the Scheduler is otherwise out of work, it'll block
+ * herein waiting for external events to occur.
+ *
+ * This file mirrors the select()-based functionality 
+ * for POSIX / Unix platforms in rts/Select.c, but for
+ * Win32.
+ *
+ */
+#include "Rts.h"
+#include "Schedule.h"
+#include "AwaitEvent.h"
+#include <windows.h>
+#include "win32/AsyncIO.h"
+
+// Used to avoid calling abandonRequestWait() if we don't need to.
+// Protected by sched_mutex.
+static nat workerWaitingForRequests = 0;
+
+void
+awaitEvent(rtsBool wait)
+{
+  int ret;
+
+  do {
+    /* Try to de-queue completed IO requests
+     */
+    workerWaitingForRequests = 1;
+    ret = awaitRequests(wait);
+    workerWaitingForRequests = 0;
+    if (!ret) { 
+      return; /* still hold the lock */
+    }
+
+    // Return to the scheduler if:
+    //
+    //  - we were interrupted
+    //  - new threads have arrived
+
+  } while (wait
+	   && sched_state == SCHED_RUNNING
+	   && emptyRunQueue(&MainCapability)
+      );
+}
+#endif