Move {blocked,sleeping}_queue from scheduler global vars to CapIOManager

The blocked_queue_{hd,tl} and the sleeping_queue are currently
cooperatively managed between the scheduler and (some but not all of)
the non-threaded I/O manager implementations.

They lived as global vars with the scheduler, but are poked by I/O
primops and the I/O manager backends.

This patch is a step on the path towards making the management of I/O or
timer blocking belong to the I/O managers and not the scheduler.

Specifically, this patch moves the {blocked,sleeping}_queue from being
global vars in the scheduler to being members of the CapIOManager struct
within each Capability. They are not yet exclusively used by the I/O
managers: they are still poked from a couple other places, notably in
the scheduler before calling awaitEvent.

1 files changed, 16 insertions, 0 deletions

diff --git a/rts/IOManager.h b/rts/IOManager.h
index f1d8cfe5c2..515cfc2f85 100644
--- a/rts/IOManager.h
+++ b/rts/IOManager.h
@@ -43,6 +43,22 @@ typedef struct {
     /* Control FD for the MIO manager for this capability */
     int control_fd;
 #endif
+#else // !defined(THREADED_RTS)
+    /* Thread queue for threads blocked on I/O completion.
+     * Used by the select() and Win32 MIO I/O managers. It is not used by
+     * the WinIO I/O manager, though it remains defined in this case.
+     */
+    StgTSO *blocked_queue_hd;
+    StgTSO *blocked_queue_tl;
+
+    /* Thread queue for threads blocked on timeouts.
+     * Used by the select() I/O manager only. It is grossly inefficient, like
+     * everything else to do with the select() I/O manager.
+     *
+     * TODO: It is not used by any of the Windows I/O managers, though it
+     * remains defined for them. This is an oddity that should be resolved.
+     */
+    StgTSO *sleeping_queue;
 #endif
 
 } CapIOManager;