winio: Multiple refactorings and support changes.

15 files changed, 134 insertions, 476 deletions

diff --git a/rts/FileLock.c b/rts/FileLock.c
index 351d2a58f7..34f4046b38 100644
--- a/rts/FileLock.c
+++ b/rts/FileLock.c
@@ -25,10 +25,10 @@ typedef struct {
 
 // Two hash tables.  The first maps objects (device/inode pairs) to
 // Lock objects containing the number of active readers or writers.  The
-// second maps file descriptors to lock objects, so that we can unlock
-// by FD without needing to fstat() again.
+// second maps file descriptors or file handles to lock objects, so that we can
+// unlock by FD or HANDLE without needing to fstat() again.
 static HashTable *obj_hash;
-static HashTable *fd_hash;
+static HashTable *key_hash;
 
 #if defined(THREADED_RTS)
 static Mutex file_lock_mutex;
@@ -53,7 +53,7 @@ void
 initFileLocking(void)
 {
     obj_hash = allocHashTable();
-    fd_hash  = allocHashTable(); /* ordinary word-based table */
+    key_hash  = allocHashTable(); /* ordinary word-based table */
 #if defined(THREADED_RTS)
     initMutex(&file_lock_mutex);
 #endif
@@ -69,14 +69,14 @@ void
 freeFileLocking(void)
 {
     freeHashTable(obj_hash, freeLock);
-    freeHashTable(fd_hash,  NULL);
+    freeHashTable(key_hash,  NULL);
 #if defined(THREADED_RTS)
     closeMutex(&file_lock_mutex);
 #endif
 }
 
 int
-lockFile(int fd, StgWord64 dev, StgWord64 ino, int for_writing)
+lockFile(StgWord id, StgWord64 dev, StgWord64 ino, int for_writing)
 {
     Lock key, *lock;
 
@@ -94,7 +94,7 @@ lockFile(int fd, StgWord64 dev, StgWord64 ino, int for_writing)
         lock->inode  = ino;
         lock->readers = for_writing ? -1 : 1;
         insertHashTable_(obj_hash, (StgWord)lock, (void *)lock, hashLock);
-        insertHashTable(fd_hash, fd, lock);
+        insertHashTable(key_hash, id, lock);
         RELEASE_LOCK(&file_lock_mutex);
         return 0;
     }
@@ -105,7 +105,7 @@ lockFile(int fd, StgWord64 dev, StgWord64 ino, int for_writing)
             RELEASE_LOCK(&file_lock_mutex);
             return -1;
         }
-        insertHashTable(fd_hash, fd, lock);
+        insertHashTable(key_hash, id, lock);
         lock->readers++;
         RELEASE_LOCK(&file_lock_mutex);
         return 0;
@@ -113,15 +113,15 @@ lockFile(int fd, StgWord64 dev, StgWord64 ino, int for_writing)
 }
 
 int
-unlockFile(int fd)
+unlockFile(StgWord id)
 {
     Lock *lock;
 
     ACQUIRE_LOCK(&file_lock_mutex);
 
-    lock = lookupHashTable(fd_hash, fd);
+    lock = lookupHashTable(key_hash, id);
     if (lock == NULL) {
-        // errorBelch("unlockFile: fd %d not found", fd);
+        // errorBelch("unlockFile: key %d not found", key);
         // This is normal: we didn't know when calling unlockFile
         // whether this FD referred to a locked file or not.
         RELEASE_LOCK(&file_lock_mutex);
@@ -138,7 +138,7 @@ unlockFile(int fd)
         removeHashTable_(obj_hash, (StgWord)lock, NULL, hashLock, cmpLocks);
         stgFree(lock);
     }
-    removeHashTable(fd_hash, fd, NULL);
+    removeHashTable(key_hash, id, NULL);
 
     RELEASE_LOCK(&file_lock_mutex);
     return 0;
diff --git a/rts/Prelude.h b/rts/Prelude.h
index c6971677af..0527218da0 100644
--- a/rts/Prelude.h
+++ b/rts/Prelude.h
@@ -52,8 +52,12 @@ PRELUDE_CLOSURE(base_GHCziExceptionziType_overflowException_closure);
 
 PRELUDE_CLOSURE(base_GHCziConcziSync_runSparks_closure);
 PRELUDE_CLOSURE(base_GHCziConcziIO_ensureIOManagerIsRunning_closure);
+PRELUDE_CLOSURE(base_GHCziConcziIO_interruptIOManager_closure);
 PRELUDE_CLOSURE(base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure);
 PRELUDE_CLOSURE(base_GHCziConcziSignal_runHandlersPtr_closure);
+#if defined(mingw32_HOST_OS)
+PRELUDE_CLOSURE(base_GHCziEventziWindows_processRemoteCompletion_closure);
+#endif
 
 PRELUDE_CLOSURE(base_GHCziTopHandler_flushStdHandles_closure);
 PRELUDE_CLOSURE(base_GHCziTopHandler_runMainIO_closure);
@@ -85,8 +89,12 @@ PRELUDE_INFO(base_GHCziStable_StablePtr_con_info);
 
 #define runSparks_closure         DLL_IMPORT_DATA_REF(base_GHCziConcziSync_runSparks_closure)
 #define ensureIOManagerIsRunning_closure DLL_IMPORT_DATA_REF(base_GHCziConcziIO_ensureIOManagerIsRunning_closure)
+#define interruptIOManager_closure DLL_IMPORT_DATA_REF(base_GHCziConcziIO_interruptIOManager_closure)
 #define ioManagerCapabilitiesChanged_closure DLL_IMPORT_DATA_REF(base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure)
 #define runHandlersPtr_closure       DLL_IMPORT_DATA_REF(base_GHCziConcziSignal_runHandlersPtr_closure)
+#if defined(mingw32_HOST_OS)
+#define processRemoteCompletion_closure DLL_IMPORT_DATA_REF(base_GHCziEventziWindows_processRemoteCompletion_closure)
+#endif
 
 #define flushStdHandles_closure   DLL_IMPORT_DATA_REF(base_GHCziTopHandler_flushStdHandles_closure)
 #define runMainIO_closure   DLL_IMPORT_DATA_REF(base_GHCziTopHandler_runMainIO_closure)
diff --git a/rts/RtsStartup.c b/rts/RtsStartup.c
index 31f8267708..a52c02190e 100644
--- a/rts/RtsStartup.c
+++ b/rts/RtsStartup.c
@@ -46,7 +46,8 @@
 #endif
 
 #if defined(mingw32_HOST_OS) && !defined(THREADED_RTS)
-#include "win32/AsyncIO.h"
+#include "win32/AsyncMIO.h"
+#include "win32/AsyncWinIO.h"
 #endif
 
 #if defined(mingw32_HOST_OS)
@@ -299,10 +300,13 @@ hs_init_ghc(int *argc, char **argv[], RtsConfig rts_config)
     getStablePtr((StgPtr)nestedAtomically_closure);
     getStablePtr((StgPtr)runSparks_closure);
     getStablePtr((StgPtr)ensureIOManagerIsRunning_closure);
+    getStablePtr((StgPtr)interruptIOManager_closure);
     getStablePtr((StgPtr)ioManagerCapabilitiesChanged_closure);
 #if !defined(mingw32_HOST_OS)
     getStablePtr((StgPtr)blockedOnBadFD_closure);
     getStablePtr((StgPtr)runHandlersPtr_closure);
+#else
+    getStablePtr((StgPtr)processRemoteCompletion_closure);
 #endif
 
     // Initialize the top-level handler system
@@ -338,7 +342,10 @@ hs_init_ghc(int *argc, char **argv[], RtsConfig rts_config)
 #endif
 
 #if defined(mingw32_HOST_OS) && !defined(THREADED_RTS)
-    startupAsyncIO();
+   if (is_io_mng_native_p())
+      startupAsyncWinIO();
+    else
+      startupAsyncIO();
 #endif
 
     x86_init_fpu();
@@ -520,7 +527,10 @@ hs_exit_(bool wait_foreign)
 #endif
 
 #if defined(mingw32_HOST_OS) && !defined(THREADED_RTS)
-    shutdownAsyncIO(wait_foreign);
+    if (is_io_mng_native_p())
+      shutdownAsyncWinIO(wait_foreign);
+    else
+      shutdownAsyncIO(wait_foreign);
 #endif
 
     /* free hash table storage */
diff --git a/rts/RtsSymbols.c b/rts/RtsSymbols.c
index 0f0bd56c82..ff430d0137 100644
--- a/rts/RtsSymbols.c
+++ b/rts/RtsSymbols.c
@@ -26,6 +26,7 @@
 #include <io.h>
 #include <windows.h>
 #include <shfolder.h> /* SHGetFolderPathW */
+#include "win32/AsyncWinIO.h"
 #endif
 
 #if defined(openbsd_HOST_OS)
@@ -142,11 +143,15 @@
       /* see Note [Symbols for MinGW's printf] */        \
       SymI_HasProto(_lock_file)                          \
       SymI_HasProto(_unlock_file)                        \
+      SymI_HasProto(__mingw_vsnwprintf)                  \
+      /* ^^ Need to figure out why this is needed.  */   \
       /* See Note [_iob_func symbol] */                  \
       RTS_WIN64_ONLY(SymI_HasProto_redirect(             \
          __imp___acrt_iob_func, __rts_iob_func, true))   \
       RTS_WIN32_ONLY(SymI_HasProto_redirect(             \
-         __imp____acrt_iob_func, __rts_iob_func, true))
+         __imp____acrt_iob_func, __rts_iob_func, true))  \
+      SymI_HasProto(__mingw_vsnwprintf)
+      /* ^^ Need to figure out why this is needed.  */
 
 #define RTS_MINGW_COMPAT_SYMBOLS                         \
       SymI_HasProto_deprecated(access)                   \
@@ -337,11 +342,16 @@
    SymI_HasProto(blockUserSignals)      \
    SymI_HasProto(unblockUserSignals)
 #else
-#define RTS_USER_SIGNALS_SYMBOLS        \
-   SymI_HasProto(ioManagerWakeup)       \
-   SymI_HasProto(sendIOManagerEvent)    \
-   SymI_HasProto(readIOManagerEvent)    \
-   SymI_HasProto(getIOManagerEvent)     \
+#define RTS_USER_SIGNALS_SYMBOLS             \
+   SymI_HasProto(registerNewIOCPHandle)      \
+   SymI_HasProto(getOverlappedEntries)       \
+   SymI_HasProto(servicedIOEntries)          \
+   SymI_HasProto(completeSynchronousRequest) \
+   SymI_HasProto(registerAlertableWait)      \
+   SymI_HasProto(ioManagerWakeup)            \
+   SymI_HasProto(sendIOManagerEvent)         \
+   SymI_HasProto(readIOManagerEvent)         \
+   SymI_HasProto(getIOManagerEvent)          \
    SymI_HasProto(console_handler)
 #endif
 
diff --git a/rts/package.conf.in b/rts/package.conf.in
index 45866a1ecd..a03eff6a14 100644
--- a/rts/package.conf.in
+++ b/rts/package.conf.in
@@ -105,8 +105,12 @@ ld-options:
          , "-Wl,-u,_base_GHCziExceptionziType_overflowException_closure"
          , "-Wl,-u,_base_GHCziConcziSync_runSparks_closure"
          , "-Wl,-u,_base_GHCziConcziIO_ensureIOManagerIsRunning_closure"
+         , "-Wl,-u,_base_GHCziConcziIO_interruptIOManager_closure"
          , "-Wl,-u,_base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure"
          , "-Wl,-u,_base_GHCziConcziSignal_runHandlersPtr_closure"
+#if defined(mingw32_HOST_OS)
+         , "-Wl,-u,_base_GHCziEventziWindows_processRemoteCompletion_closure"
+#endif
          , "-Wl,-u,_base_GHCziTopHandler_flushStdHandles_closure"
          , "-Wl,-u,_base_GHCziTopHandler_runMainIO_closure"
          , "-Wl,-u,_ghczmprim_GHCziTypes_Czh_con_info"
@@ -214,8 +218,12 @@ ld-options:
          , "-Wl,-u,base_GHCziExceptionziType_overflowException_closure"
          , "-Wl,-u,base_GHCziConcziSync_runSparks_closure"
          , "-Wl,-u,base_GHCziConcziIO_ensureIOManagerIsRunning_closure"
+         , "-Wl,-u,base_GHCziConcziIO_interruptIOManager_closure"
          , "-Wl,-u,base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure"
          , "-Wl,-u,base_GHCziConcziSignal_runHandlersPtr_closure"
+#if defined(mingw32_HOST_OS)
+         , "-Wl,-u,base_GHCziEventziWindows_processRemoteCompletion_closure"
+#endif
          , "-Wl,-u,base_GHCziTopHandler_flushStdHandles_closure"
          , "-Wl,-u,base_GHCziTopHandler_runMainIO_closure"
          , "-Wl,-u,ghczmprim_GHCziTypes_Czh_con_info"
diff --git a/rts/rts.cabal.in b/rts/rts.cabal.in
index ebbd9a9e71..a16582a7f5 100644
--- a/rts/rts.cabal.in
+++ b/rts/rts.cabal.in
@@ -97,6 +97,7 @@ library
           dbghelp
           -- for process information
           psapi
+       -- TODO: Hadrian will use this cabal file, so drop WINVER from Hadrian's configs.
        -- Minimum supported Windows version.
        -- These numbers can be found at:
        --  https://msdn.microsoft.com/en-us/library/windows/desktop/aa383745(v=vs.85).aspx
@@ -231,6 +232,7 @@ library
          "-Wl,-u,_base_GHCziEventziThread_blockedOnBadFD_closure"
          "-Wl,-u,_base_GHCziConcziSync_runSparks_closure"
          "-Wl,-u,_base_GHCziConcziIO_ensureIOManagerIsRunning_closure"
+         "-Wl,-u,_base_GHCziConcziIO_interruptIOManager_closure"
          "-Wl,-u,_base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure"
          "-Wl,-u,_base_GHCziConcziSignal_runHandlersPtr_closure"
          "-Wl,-u,_base_GHCziTopHandler_flushStdHandles_closure"
@@ -310,6 +312,7 @@ library
          "-Wl,-u,base_GHCziEventziThread_blockedOnBadFD_closure"
          "-Wl,-u,base_GHCziConcziSync_runSparks_closure"
          "-Wl,-u,base_GHCziConcziIO_ensureIOManagerIsRunning_closure"
+         "-Wl,-u,base_GHCziConcziIO_interruptIOManager_closure"
          "-Wl,-u,base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure"
          "-Wl,-u,base_GHCziConcziSignal_runHandlersPtr_closure"
          "-Wl,-u,base_GHCziTopHandler_flushStdHandles_closure"
@@ -366,6 +369,17 @@ library
         -- This symbol is useful in gdb, but not referred to anywhere,
         -- so we need to force it to be included in the binary.
         ld-options: "-Wl,-u,findPtr"
+         -- This symbol is useful in gdb, but not referred to anywhere,
+         -- so we need to force it to be included in the binary.
+         "-Wl,-u,findPtr"
+
+    if os(windows)
+      if flag(leading-underscore)
+        ld-options:
+           "-Wl,-u,_base_GHCziEventziWindows_processRemoteCompletion_closure"
+      else
+        ld-options:
+           "-Wl,-u,base_GHCziEventziWindows_processRemoteCompletion_closure"
 
     if os(osx)
       ld-options: "-Wl,-search_paths_first"
@@ -497,7 +511,8 @@ library
                -- I wish we had wildcards..., this would be:
                -- *.c hooks/**/*.c sm/**/*.c eventlog/**/*.c linker/**/*.c
     if os(windows)
-       c-sources: win32/AsyncIO.c
+       c-sources: win32/AsyncMIO.c
+                  win32/AsyncWinIO.c
                   win32/AwaitEvent.c
                   win32/ConsoleHandler.c
                   win32/GetEnv.c
diff --git a/rts/win32/AsyncIO.c b/rts/win32/AsyncIO.c
deleted file mode 100644
index 49da79d2dd..0000000000
--- a/rts/win32/AsyncIO.c
+++ /dev/null
@@ -1,384 +0,0 @@
-/* AsyncIO.c
- *
- * Integrating Win32 asynchronous I/O with the GHC RTS.
- *
- * (c) sof, 2002-2003.
- */
-
-#if !defined(THREADED_RTS)
-
-#include "Rts.h"
-#include "RtsUtils.h"
-#include <windows.h>
-#include <stdio.h>
-#include "Schedule.h"
-#include "Capability.h"
-#include "win32/AsyncIO.h"
-#include "win32/IOManager.h"
-
-/*
- * Overview:
- *
- * Haskell code issue asynchronous I/O requests via the
- * async{Read,Write,DoOp}# primops. These cause addIORequest()
- * to be invoked, which forwards the request to the underlying
- * asynchronous I/O subsystem. Each request is tagged with a unique
- * ID.
- *
- * addIORequest() returns this ID, so that when the blocked CH
- * thread is added onto blocked_queue, its TSO is annotated with
- * it. Upon completion of an I/O request, the async I/O handling
- * code makes a back-call to signal its completion; the local
- * onIOComplete() routine. It adds the IO request ID (along with
- * its result data) to a queue of completed requests before returning.
- *
- * The queue of completed IO request is read by the thread operating
- * the RTS scheduler. It de-queues the CH threads corresponding
- * to the request IDs, making them runnable again.
- *
- */
-
-typedef struct CompletedReq {
-    unsigned int   reqID;
-    HsInt          len;
-    HsInt          errCode;
-} CompletedReq;
-
-#define MAX_REQUESTS 200
-
-static CRITICAL_SECTION queue_lock;
-static HANDLE           completed_req_event = INVALID_HANDLE_VALUE;
-static HANDLE           abandon_req_wait = INVALID_HANDLE_VALUE;
-static HANDLE           wait_handles[2];
-static CompletedReq     completedTable[MAX_REQUESTS];
-static int              completed_hw;
-static HANDLE           completed_table_sema;
-static int              issued_reqs;
-
-static void
-onIOComplete(unsigned int reqID,
-             int   fd STG_UNUSED,
-             HsInt len,
-             void* buf STG_UNUSED,
-             HsInt errCode)
-{
-    DWORD dwRes;
-    /* Deposit result of request in queue/table..when there's room. */
-    dwRes = WaitForSingleObject(completed_table_sema, INFINITE);
-    switch (dwRes) {
-    case WAIT_OBJECT_0:
-    case WAIT_ABANDONED:
-        break;
-    default:
-        /* Not likely */
-        fprintf(stderr,
-                "onIOComplete: failed to grab table semaphore (res=%d, err=%d), "
-                "dropping request 0x%x\n", reqID, dwRes, GetLastError());
-        fflush(stderr);
-        return;
-    }
-    EnterCriticalSection(&queue_lock);
-    if (completed_hw == MAX_REQUESTS) {
-        /* Shouldn't happen */
-        fprintf(stderr, "onIOComplete: ERROR -- Request table overflow (%d); "
-                        "dropping.\n", reqID);
-        fflush(stderr);
-    } else {
-#if 0
-        fprintf(stderr, "onCompl: %d %d %d %d %d\n",
-                reqID, len, errCode, issued_reqs, completed_hw);
-        fflush(stderr);
-#endif
-        completedTable[completed_hw].reqID   = reqID;
-        completedTable[completed_hw].len     = len;
-        completedTable[completed_hw].errCode = errCode;
-        completed_hw++;
-        issued_reqs--;
-        if (completed_hw == 1) {
-            /* The event is used to wake up the scheduler thread should it
-             * be blocked waiting for requests to complete. The event resets
-             * once that thread has cleared out the request queue/table.
-             */
-            SetEvent(completed_req_event);
-        }
-    }
-    LeaveCriticalSection(&queue_lock);
-}
-
-unsigned int
-addIORequest(int   fd,
-             bool  forWriting,
-             bool  isSock,
-             HsInt len,
-             char* buf)
-{
-    EnterCriticalSection(&queue_lock);
-    issued_reqs++;
-    LeaveCriticalSection(&queue_lock);
-#if 0
-    fprintf(stderr, "addIOReq: %d %d %d\n", fd, forWriting, len);
-    fflush(stderr);
-#endif
-    return AddIORequest(fd,forWriting,isSock,len,buf,onIOComplete);
-}
-
-unsigned int
-addDelayRequest(HsInt usecs)
-{
-    EnterCriticalSection(&queue_lock);
-    issued_reqs++;
-    LeaveCriticalSection(&queue_lock);
-#if 0
-    fprintf(stderr, "addDelayReq: %d\n", usecs); fflush(stderr);
-#endif
-    return AddDelayRequest(usecs,onIOComplete);
-}
-
-unsigned int
-addDoProcRequest(void* proc, void* param)
-{
-    EnterCriticalSection(&queue_lock);
-    issued_reqs++;
-    LeaveCriticalSection(&queue_lock);
-#if 0
-    fprintf(stderr, "addProcReq: %p %p\n", proc, param); fflush(stderr);
-#endif
-    return AddProcRequest(proc,param,onIOComplete);
-}
-
-
-int
-startupAsyncIO()
-{
-    if (!StartIOManager()) {
-        return 0;
-    }
-    InitializeCriticalSection(&queue_lock);
-    /* Create a pair of events:
-     *
-     *    - completed_req_event -- signals the deposit of request result;
-     *                             manual reset.
-     *    - abandon_req_wait    -- external OS thread tells current
-     *                             RTS/Scheduler thread to abandon wait
-     *                             for IO request completion.
-     *                             Auto reset.
-     */
-    completed_req_event = CreateEvent (NULL, TRUE,  FALSE, NULL);
-    abandon_req_wait    = CreateEvent (NULL, FALSE, FALSE, NULL);
-    wait_handles[0] = completed_req_event;
-    wait_handles[1] = abandon_req_wait;
-    completed_hw = 0;
-    if ( !(completed_table_sema = CreateSemaphore(NULL, MAX_REQUESTS,
-                                                  MAX_REQUESTS, NULL)) ) {
-        DWORD rc = GetLastError();
-        fprintf(stderr, "startupAsyncIO: CreateSemaphore failed 0x%x\n",
-                (int)rc);
-        fflush(stderr);
-    }
-
-    return ( completed_req_event  != INVALID_HANDLE_VALUE &&
-             abandon_req_wait     != INVALID_HANDLE_VALUE &&
-             completed_table_sema != NULL );
-}
-
-void
-shutdownAsyncIO(bool wait_threads)
-{
-    ShutdownIOManager(wait_threads);
-    if (completed_req_event != INVALID_HANDLE_VALUE) {
-        CloseHandle(completed_req_event);
-        completed_req_event = INVALID_HANDLE_VALUE;
-    }
-    if (abandon_req_wait != INVALID_HANDLE_VALUE) {
-        CloseHandle(abandon_req_wait);
-        abandon_req_wait = INVALID_HANDLE_VALUE;
-    }
-    if (completed_table_sema != NULL) {
-        CloseHandle(completed_table_sema);
-        completed_table_sema = NULL;
-    }
-    DeleteCriticalSection(&queue_lock);
-}
-
-/*
- * Function: awaitRequests(wait)
- *
- * Check for the completion of external IO work requests. Worker
- * threads signal completion of IO requests by depositing them
- * in a table (completedTable). awaitRequests() matches up
- * requests in that table with threads on the blocked_queue,
- * making the threads whose IO requests have completed runnable
- * again.
- *
- * awaitRequests() is called by the scheduler periodically _or_ if
- * it is out of work, and need to wait for the completion of IO
- * requests to make further progress. In the latter scenario,
- * awaitRequests() will simply block waiting for worker threads
- * to complete if the 'completedTable' is empty.
- */
-int
-awaitRequests(bool wait)
-{
-#if !defined(THREADED_RTS)
-  // none of this is actually used in the threaded RTS
-
-start:
-#if 0
-    fprintf(stderr, "awaitRequests(): %d %d %d\n",
-            issued_reqs, completed_hw, wait);
-    fflush(stderr);
-#endif
-    EnterCriticalSection(&queue_lock);
-    // Nothing immediately available & we won't wait
-    if ((!wait && completed_hw == 0)
-#if 0
-        // If we just return when wait==false, we'll go into a busy
-        // wait loop, so I disabled this condition --SDM 18/12/2003
-        (issued_reqs == 0 && completed_hw == 0)
-#endif
-        ) {
-        LeaveCriticalSection(&queue_lock);
-        return 0;
-    }
-    if (completed_hw == 0) {
-        // empty table, drop lock and wait
-        LeaveCriticalSection(&queue_lock);
-        if ( wait && sched_state == SCHED_RUNNING ) {
-            DWORD dwRes = WaitForMultipleObjects(2, wait_handles,
-                                                 FALSE, INFINITE);
-            switch (dwRes) {
-            case WAIT_OBJECT_0:
-                // a request was completed
-                break;
-            case WAIT_OBJECT_0 + 1:
-            case WAIT_TIMEOUT:
-                // timeout (unlikely) or told to abandon waiting
-                return 0;
-            case WAIT_FAILED: {
-                DWORD dw = GetLastError();
-                fprintf(stderr, "awaitRequests: wait failed -- "
-                                "error code: %lu\n", dw); fflush(stderr);
-                return 0;
-            }
-            default:
-                fprintf(stderr, "awaitRequests: unexpected wait return "
-                                "code %lu\n", dwRes); fflush(stderr);
-                return 0;
-            }
-        } else {
-            return 0;
-        }
-        goto start;
-    } else {
-        int i;
-        StgTSO *tso, *prev;
-
-        for (i=0; i < completed_hw; i++) {
-            /* For each of the completed requests, match up their Ids
-             * with those of the threads on the blocked_queue. If the
-             * thread that made the IO request has been subsequently
-             * killed (and removed from blocked_queue), no match will
-             * be found for that request Id.
-             *
-             * i.e., killing a Haskell thread doesn't attempt to cancel
-             * the IO request it is blocked on.
-             *
-             */
-            unsigned int rID = completedTable[i].reqID;
-
-            prev = NULL;
-            for(tso = blocked_queue_hd; tso != END_TSO_QUEUE;
-                  tso = tso->_link) {
-
-                switch(tso->why_blocked) {
-                case BlockedOnRead:
-                case BlockedOnWrite:
-                case BlockedOnDoProc:
-                    if (tso->block_info.async_result->reqID == rID) {
-                        // Found the thread blocked waiting on request;
-                        // stodgily fill
-                        // in its result block.
-                        tso->block_info.async_result->len =
-                          completedTable[i].len;
-                        tso->block_info.async_result->errCode =
-                          completedTable[i].errCode;
-
-                        // Drop the matched TSO from blocked_queue
-                        if (prev) {
-                            setTSOLink(&MainCapability, prev, tso->_link);
-                        } else {
-                            blocked_queue_hd = tso->_link;
-                        }
-                        if (blocked_queue_tl == tso) {
-                            blocked_queue_tl = prev ? prev : END_TSO_QUEUE;
-                        }
-
-                        // Terminates the run queue + this inner for-loop.
-                        tso->_link = END_TSO_QUEUE;
-                        tso->why_blocked = NotBlocked;
-                        // save the StgAsyncIOResult in the
-                        // stg_block_async_info stack frame, because
-                        // the block_info field will be overwritten by
-                        // pushOnRunQueue().
-                        tso->stackobj->sp[1] = (W_)tso->block_info.async_result;
-                        pushOnRunQueue(&MainCapability, tso);
-                        break;
-                    }
-                    break;
-                default:
-                    if (tso->why_blocked != NotBlocked) {
-                        barf("awaitRequests: odd thread state");
-                    }
-                    break;
-                }
-
-                prev = tso;
-            }
-            /* Signal that there's completed table slots available */
-            if ( !ReleaseSemaphore(completed_table_sema, 1, NULL) ) {
-                DWORD dw = GetLastError();
-                fprintf(stderr, "awaitRequests: failed to signal semaphore "
-                                "(error code=0x%x)\n", (int)dw);
-                fflush(stderr);
-            }
-        }
-        completed_hw = 0;
-        ResetEvent(completed_req_event);
-        LeaveCriticalSection(&queue_lock);
-        return 1;
-    }
-#endif /* !THREADED_RTS */
-}
-
-/*
- * Function: abandonRequestWait()
- *
- * Wake up a thread that's blocked waiting for new IO requests
- * to complete (via awaitRequests().)
- */
-void
-abandonRequestWait( void )
-{
-    /* the event is auto-reset, but in case there's no thread
-     * already waiting on the event, we want to return it to
-     * a non-signalled state.
-     *
-     * Careful!  There is no synchronisation between
-     * abandonRequestWait and awaitRequest, which means that
-     * abandonRequestWait might be called just before a thread
-     * goes into a wait, and we miss the abandon signal.  So we
-     * must SetEvent() here rather than PulseEvent() to ensure
-     * that the event isn't lost.  We can re-optimise by resetting
-     * the event somewhere safe if we know the event has been
-     * properly serviced (see resetAbandon() below).  --SDM 18/12/2003
-     */
-    SetEvent(abandon_req_wait);
-}
-
-void
-resetAbandonRequestWait( void )
-{
-    ResetEvent(abandon_req_wait);
-}
-
-#endif /* !defined(THREADED_RTS) */
diff --git a/rts/win32/AsyncIO.h b/rts/win32/AsyncIO.h
deleted file mode 100644
index 75d0e0460d..0000000000
--- a/rts/win32/AsyncIO.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/* AsyncIO.h
- *
- * Integrating Win32 asynchronous I/O with the GHC RTS.
- *
- * (c) sof, 2002-2003.
- */
-
-#pragma once
-
-extern unsigned int
-addIORequest(int   fd,
-             bool  forWriting,
-             bool  isSock,
-             HsInt len,
-             char* buf);
-extern unsigned int addDelayRequest(HsInt usecs);
-extern unsigned int addDoProcRequest(void* proc, void* param);
-extern int  startupAsyncIO(void);
-extern void shutdownAsyncIO(bool wait_threads);
-
-extern int awaitRequests(bool wait);
-
-extern void abandonRequestWait(void);
-extern void resetAbandonRequestWait(void);
diff --git a/rts/win32/AwaitEvent.c b/rts/win32/AwaitEvent.c
index b639121c87..6a621d6ef5 100644
--- a/rts/win32/AwaitEvent.c
+++ b/rts/win32/AwaitEvent.c
@@ -14,15 +14,18 @@
  *
  */
 #include "Rts.h"
+#include "RtsFlags.h"
 #include "Schedule.h"
 #include "AwaitEvent.h"
 #include <windows.h>
-#include "win32/AsyncIO.h"
+#include "win32/AsyncMIO.h"
+#include "win32/AsyncWinIO.h"
 #include "win32/ConsoleHandler.h"
+#include <stdbool.h>
 
 // Used to avoid calling abandonRequestWait() if we don't need to.
 // Protected by sched_mutex.
-static uint32_t workerWaitingForRequests = 0;
+static bool workerWaitingForRequests = false;
 
 void
 awaitEvent(bool wait)
@@ -30,9 +33,12 @@ awaitEvent(bool wait)
   do {
     /* Try to de-queue completed IO requests
      */
-    workerWaitingForRequests = 1;
-    awaitRequests(wait);
-    workerWaitingForRequests = 0;
+    workerWaitingForRequests = true;
+    if (is_io_mng_native_p())
+      awaitAsyncRequests(wait);
+    else
+      awaitRequests(wait);
+    workerWaitingForRequests = false;
 
     // If a signal was raised, we need to service it
     // XXX the scheduler loop really should be calling
diff --git a/rts/win32/ConsoleHandler.c b/rts/win32/ConsoleHandler.c
index 3ddf4103da..05d15868eb 100644
--- a/rts/win32/ConsoleHandler.c
+++ b/rts/win32/ConsoleHandler.c
@@ -1,13 +1,15 @@
 /*
  * Console control handler support.
  *
+ * NOTE: This is the MIO manager, only used for --io-manager=posix.
+ *       For the WINIO manager see base in the GHC.Event modules.
  */
 #include "Rts.h"
 #include <windows.h>
 #include "ConsoleHandler.h"
 #include "Schedule.h"
 #include "RtsUtils.h"
-#include "AsyncIO.h"
+#include "AsyncMIO.h"
 #include "RtsSignals.h"
 
 extern int stg_InstallConsoleEvent(int action, StgStablePtr *handler);
@@ -86,7 +88,6 @@ static BOOL WINAPI shutdown_handler(DWORD dwCtrlType)
         return false;
     case CTRL_C_EVENT:
     case CTRL_BREAK_EVENT:
-
         // If we're already trying to interrupt the RTS, terminate with
         // extreme prejudice.  So the first ^C tries to exit the program
         // cleanly, and the second one just kills it.
@@ -223,12 +224,12 @@ static BOOL WINAPI generic_handler(DWORD dwCtrlType)
 
 #if defined(THREADED_RTS)
         sendIOManagerEvent((StgWord8) ((dwCtrlType<<1) | 1));
+        interruptIOManagerEvent ();
 #else
         if ( stg_pending_events < N_PENDING_EVENTS ) {
             stg_pending_buf[stg_pending_events] = dwCtrlType;
             stg_pending_events++;
         }
-
         // we need to wake up awaitEvent()
         abandonRequestWait();
 #endif
diff --git a/rts/win32/ConsoleHandler.h b/rts/win32/ConsoleHandler.h
index 06af9dd0d0..bb7278abba 100644
--- a/rts/win32/ConsoleHandler.h
+++ b/rts/win32/ConsoleHandler.h
@@ -1,6 +1,8 @@
 /*
  * Console control handler support.
  *
+ * NOTE: This is the MIO manager, only used for --io-manager=posix.
+ *       For the WINIO manager see base in the GHC.Event modules.
  */
 
 #pragma once
@@ -16,24 +18,24 @@
  */
 
 #if !defined(THREADED_RTS)
-/* 
+/*
  * under THREADED_RTS, console events are passed to the IO manager
  * thread, which starts up the handler.  See ThrIOManager.c.
  */
 
 /*
- * Function: signals_pending() 
- * 
+ * Function: signals_pending()
+ *
  * Used by the RTS to check whether new signals have been 'recently' reported.
- * If so, the RTS arranges for the delivered signals to be handled by 
- * de-queueing them from their table, running the associated Haskell 
+ * If so, the RTS arranges for the delivered signals to be handled by
+ * de-queueing them from their table, running the associated Haskell
  * signal handler.
  */
 extern StgInt stg_pending_events;
 
 #define signals_pending() ( stg_pending_events > 0)
 
-/* 
+/*
  * Function: anyUserHandlers()
  *
  * Used by the Scheduler to decide whether its worth its while to stick
diff --git a/rts/win32/IOManager.c b/rts/win32/IOManager.c
index e5da32b982..47bcf4bcf4 100644
--- a/rts/win32/IOManager.c
+++ b/rts/win32/IOManager.c
@@ -3,6 +3,9 @@
  * Non-blocking / asynchronous I/O for Win32.
  *
  * (c) sof, 2002-2003.
+ *
+ * NOTE: This is the MIO manager, only used for --io-manager=posix.
+ *       For the WINIO manager see base in the GHC.Event modules.
  */
 
 #if !defined(THREADED_RTS)
diff --git a/rts/win32/IOManager.h b/rts/win32/IOManager.h
index a5bd61ab1b..cb876db9cc 100644
--- a/rts/win32/IOManager.h
+++ b/rts/win32/IOManager.h
@@ -3,6 +3,9 @@
  * Non-blocking / asynchronous I/O for Win32.
  *
  * (c) sof, 2002-2003
+ *
+ * NOTE: This is the MIO manager, only used for --io-manager=posix.
+ *       For the WINIO manager see base in the GHC.Event modules.
  */
 
 #pragma once
@@ -102,3 +105,5 @@ extern int AddProcRequest ( void*          proc,
                             CompletionProc onCompletion);
 
 extern void abandonWorkRequest ( int reqID );
+
+extern void interruptIOManagerEvent ( void );
diff --git a/rts/win32/ThrIOManager.c b/rts/win32/ThrIOManager.c
index 44414b92c3..b70a178faf 100644
--- a/rts/win32/ThrIOManager.c
+++ b/rts/win32/ThrIOManager.c
@@ -5,6 +5,7 @@
  * The IO manager thread in THREADED_RTS.
  * See also libraries/base/GHC/Conc.hs.
  *
+ * NOTE: This is used by both MIO and WINIO
  * ---------------------------------------------------------------------------*/
 
 #include "Rts.h"
@@ -15,28 +16,14 @@
 // Here's the Event that we use to wake up the IO manager thread
 static HANDLE io_manager_event = INVALID_HANDLE_VALUE;
 
-// must agree with values in GHC.Conc:
-#define IO_MANAGER_WAKEUP 0xffffffff
-#define IO_MANAGER_DIE    0xfffffffe
-// spurious wakeups are returned as zero.
-// console events are ((event<<1) | 1)
-
-#if defined(THREADED_RTS)
-
 #define EVENT_BUFSIZ 256
 Mutex event_buf_mutex;
 StgWord32 event_buf[EVENT_BUFSIZ];
 uint32_t next_event;
 
-#endif
-
 HANDLE
 getIOManagerEvent (void)
 {
-    // This function has to exist even in the non-THREADED_RTS,
-    // because code in GHC.Conc refers to it.  It won't ever be called
-    // unless we're in the threaded RTS, however.
-#if defined(THREADED_RTS)
     HANDLE hRes;
 
     ACQUIRE_LOCK(&event_buf_mutex);
@@ -57,18 +44,12 @@ getIOManagerEvent (void)
 
     RELEASE_LOCK(&event_buf_mutex);
     return hRes;
-#else
-    return NULL;
-#endif
 }
 
 
 HsWord32
 readIOManagerEvent (void)
 {
-    // This function must exist even in non-THREADED_RTS,
-    // see getIOManagerEvent() above.
-#if defined(THREADED_RTS)
     HsWord32 res;
 
     ACQUIRE_LOCK(&event_buf_mutex);
@@ -77,7 +58,11 @@ readIOManagerEvent (void)
         if (next_event == 0) {
             res = 0; // no event to return
         } else {
-            res = (HsWord32)(event_buf[--next_event]);
+            do {
+               // Dequeue as many wakeup events as possible.
+                res = (HsWord32)(event_buf[--next_event]);
+            } while (res == IO_MANAGER_WAKEUP && next_event);
+
             if (next_event == 0) {
                 if (!ResetEvent(io_manager_event)) {
                     sysErrorBelch("readIOManagerEvent");
@@ -91,34 +76,45 @@ readIOManagerEvent (void)
 
     RELEASE_LOCK(&event_buf_mutex);
 
-    // debugBelch("readIOManagerEvent: %d\n", res);
+    //debugBelch("readIOManagerEvent: %d\n", res);
     return res;
-#else
-    return 0;
-#endif
 }
 
 void
 sendIOManagerEvent (HsWord32 event)
 {
-#if defined(THREADED_RTS)
     ACQUIRE_LOCK(&event_buf_mutex);
 
-    // debugBelch("sendIOManagerEvent: %d\n", event);
+    //debugBelch("sendIOManagerEvent: %d to %p\n", event, io_manager_event);
     if (io_manager_event != INVALID_HANDLE_VALUE) {
         if (next_event == EVENT_BUFSIZ) {
             errorBelch("event buffer overflowed; event dropped");
         } else {
+            event_buf[next_event++] = (StgWord32)event;
             if (!SetEvent(io_manager_event)) {
-                sysErrorBelch("sendIOManagerEvent");
+                sysErrorBelch("sendIOManagerEvent: SetEvent");
                 stg_exit(EXIT_FAILURE);
             }
-            event_buf[next_event++] = (StgWord32)event;
         }
     }
 
     RELEASE_LOCK(&event_buf_mutex);
-#endif
+}
+
+void
+interruptIOManagerEvent (void)
+{
+  if (is_io_mng_native_p ()) {
+    ACQUIRE_LOCK(&event_buf_mutex);
+
+    /* How expensive is this??.  */
+    Capability *cap;
+    cap = rts_lock();
+    rts_evalIO(&cap, interruptIOManager_closure, NULL);
+    rts_unlock(cap);
+
+    RELEASE_LOCK(&event_buf_mutex);
+  }
 }
 
 void
@@ -127,7 +123,6 @@ ioManagerWakeup (void)
     sendIOManagerEvent(IO_MANAGER_WAKEUP);
 }
 
-#if defined(THREADED_RTS)
 void
 ioManagerDie (void)
 {
@@ -145,7 +140,9 @@ ioManagerDie (void)
 void
 ioManagerStart (void)
 {
+#if defined(THREADED_RTS)
     initMutex(&event_buf_mutex);
+#endif
     next_event = 0;
 
     // Make sure the IO manager thread is running
@@ -156,4 +153,3 @@ ioManagerStart (void)
         rts_unlock(cap);
     }
 }
-#endif
diff --git a/rts/win32/libHSbase.def b/rts/win32/libHSbase.def
index de4db2244b..fb705bbd9f 100644
--- a/rts/win32/libHSbase.def
+++ b/rts/win32/libHSbase.def
@@ -27,8 +27,10 @@ EXPORTS
 	base_GHCziPtr_FunPtr_con_info
 
 	base_GHCziConcziIO_ensureIOManagerIsRunning_closure
+	base_GHCziConcziIO_interruptIOManager_closure
 	base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure
 	base_GHCziConcziSync_runSparks_closure
+	base_GHCziEventziWindows_processRemoteCompletion_closure
 
 	base_GHCziTopHandler_flushStdHandles_closure