[project @ 2005-01-21 19:58:51 by sof]

[ghc-hetmet.git] / ghc / rts / win32 / IOManager.c

diff --git a/ghc/rts/win32/IOManager.c b/ghc/rts/win32/IOManager.c
index ca5fd4d..60f6aa8 100644 (file)
--- a/ghc/rts/win32/IOManager.c
+++ b/ghc/rts/win32/IOManager.c
@@ -42,7 +42,7 @@ IOWorkerProc(PVOID param)
     WorkQueue* pq = iom->workQueue;
     WorkItem*  work;
     int        len = 0, fd = 0;
-    DWORD      errCode;
+    DWORD      errCode = 0;
     void*      complData;
 
     hWaits[0] = (HANDLE)iom->hExitEvent;
@@ -70,6 +70,11 @@ IOWorkerProc(PVOID param)
         */
        rc = WaitForMultipleObjects( 2, hWaits, FALSE, INFINITE );
 
+       if (rc == WAIT_OBJECT_0) {
+           // we received the exit event
+           return 0;
+       }
+
        EnterCriticalSection(&iom->manLock);
        /* Signal that the thread is 'non-idle' and about to consume 
         * a work item.
@@ -78,10 +83,7 @@ IOWorkerProc(PVOID param)
        iom->queueSize--;
        LeaveCriticalSection(&iom->manLock);
     
-       if ( WAIT_OBJECT_0 == rc ) {
-           /* shutdown */
-           return 0;
-       } else if ( (WAIT_OBJECT_0 + 1) == rc ) {
+       if ( rc == (WAIT_OBJECT_0 + 1) ) {
            /* work item available, fetch it. */
            if (FetchWork(pq,(void**)&work)) {
                if ( work->workKind & WORKER_READ ) {
@@ -94,9 +96,56 @@ IOWorkerProc(PVOID param)
                            errCode = WSAGetLastError();
                        }
                    } else {
+                       DWORD dw;
+
+                       while (1) {
+                       /* Do the read(), with extra-special handling for Ctrl+C */
                        len = read(work->workData.ioData.fd,
                                   work->workData.ioData.buf,
                                   work->workData.ioData.len);
+                       dw = GetLastError();
+                       if ( len == 0 && work->workData.ioData.len != 0 ) {
+                           /* Given the following scenario:
+                            *     - a console handler has been registered that handles Ctrl+C
+                            *       events.
+                            *     - we've not tweaked the 'console mode' settings to turn on
+                            *       ENABLE_PROCESSED_INPUT.
+                            *     - we're blocked waiting on input from standard input.
+                            *     - the user hits Ctrl+C.
+                            *
+                            * The OS will invoke the console handler (in a separate OS thread),
+                            * and the above read() (i.e., under the hood, a ReadFile() op) returns
+                            * 0, with the error set to ERROR_OPERATION_ABORTED. We don't
+                            * want to percolate this non-EOF condition too far back up, but ignore
+                            * it. 
+                            *
+                            * However, we do want to give the RTS an opportunity to deliver the
+                            * console event. Take care of this in the low-level console handler
+                            * in ConsoleHandler.c which wakes up the RTS thread that's blocked
+                            * waiting for I/O results from this worker (and possibly others).
+                            * It won't see any I/O, but notices and dispatches the queued up
+                            * signals/console events while in the Scheduler.
+                            *
+                            * The original, and way hackier scheme, was to have the worker
+                            * return a special return code representing aborted-due-to-ctrl-C-on-stdin,
+                            * which GHC.Conc.asyncRead would look out for and retry the I/O
+                            * call if encountered.
+                            */
+                           if ( dw == ERROR_OPERATION_ABORTED ) {
+                               /* Only do the retry when dealing with the standard input handle. */
+                               HANDLE h  = (HANDLE)GetStdHandle(STD_INPUT_HANDLE);
+                               if ( _get_osfhandle(work->workData.ioData.fd) == (long)h ) {
+                                   Sleep(0);
+                               } else {
+                                   break;
+                               }
+                           } else {
+                               break;
+                           }
+                       } else {
+                           break;
+                       }
+                       }
                        if (len == -1) { errCode = errno; }
                    }
                    complData = work->workData.ioData.buf;