2 * Console control handler support.
7 #include "ConsoleHandler.h"
13 #include "RtsSignals.h"
15 extern int stg_InstallConsoleEvent(int action, StgStablePtr *handler);
17 static BOOL WINAPI shutdown_handler(DWORD dwCtrlType);
18 static BOOL WINAPI generic_handler(DWORD dwCtrlType);
20 static rtsBool deliver_event = rtsTrue;
21 StgInt console_handler = STG_SIG_DFL;
23 #if !defined(THREADED_RTS)
25 static HANDLE hConsoleEvent = INVALID_HANDLE_VALUE;
27 #define N_PENDING_EVENTS 16
28 StgInt stg_pending_events = 0; /* number of undelivered events */
29 DWORD stg_pending_buf[N_PENDING_EVENTS]; /* their associated event numbers. */
34 * Function: initUserSignals()
36 * Initialize the console handling substrate.
41 console_handler = STG_SIG_DFL;
42 #if !defined (THREADED_RTS)
43 stg_pending_events = 0;
44 if (hConsoleEvent == INVALID_HANDLE_VALUE) {
46 CreateEvent ( NULL, /* default security attributes */
47 TRUE, /* manual-reset event */
48 FALSE, /* initially non-signalled */
56 freeSignalHandlers(void) {
60 /* Seems to be a bit of an orphan...where used? */
64 #if !defined (THREADED_RTS)
65 if (hConsoleEvent != INVALID_HANDLE_VALUE) {
66 CloseHandle(hConsoleEvent);
72 * Function: shutdown_handler()
74 * Local function that performs the default handling of Ctrl+C kind
75 * events; gently shutting down the RTS
77 * To repeat Signals.c remark -- user code may choose to override the
78 * default handler. Which is fine, assuming they put back the default
79 * handler when/if they de-install the custom handler.
82 static BOOL WINAPI shutdown_handler(DWORD dwCtrlType)
86 case CTRL_CLOSE_EVENT:
87 /* see generic_handler() comment re: this event */
90 case CTRL_BREAK_EVENT:
92 // If we're already trying to interrupt the RTS, terminate with
93 // extreme prejudice. So the first ^C tries to exit the program
94 // cleanly, and the second one just kills it.
95 if (sched_state >= SCHED_INTERRUPTING) {
96 stg_exit(EXIT_INTERRUPTED);
102 /* shutdown + logoff events are not handled here. */
110 * Function: initDefaultHandlers()
112 * Install any default signal/console handlers. Currently we install a
113 * Ctrl+C handler that shuts down the RTS in an orderly manner.
115 void initDefaultHandlers(void)
117 if ( !SetConsoleCtrlHandler(shutdown_handler, TRUE) ) {
118 errorBelch("warning: failed to install default console handler");
124 * Function: blockUserSignals()
126 * Temporarily block the delivery of further console events. Needed to
127 * avoid race conditions when GCing the stack of outstanding handlers or
128 * when emptying the stack by running the handlers.
132 blockUserSignals(void)
134 deliver_event = rtsFalse;
139 * Function: unblockUserSignals()
141 * The inverse of blockUserSignals(); re-enable the deliver of console events.
144 unblockUserSignals(void)
146 deliver_event = rtsTrue;
151 * Function: awaitUserSignals()
153 * Wait for the next console event. Currently a NOP (returns immediately.)
155 void awaitUserSignals(void)
161 #if !defined (THREADED_RTS)
163 * Function: startSignalHandlers()
165 * Run the handlers associated with the stacked up console events. Console
166 * event delivery is blocked for the duration of this call.
168 void startSignalHandlers(Capability *cap)
170 StgStablePtr handler;
172 if (console_handler < 0) {
177 ACQUIRE_LOCK(&sched_mutex);
179 handler = deRefStablePtr((StgStablePtr)console_handler);
180 while (stg_pending_events > 0) {
181 stg_pending_events--;
184 RtsFlags.GcFlags.initialStkSize,
186 (StgClosure *)handler,
188 stg_pending_buf[stg_pending_events]))));
191 RELEASE_LOCK(&sched_mutex);
192 unblockUserSignals();
194 #endif /* !THREADED_RTS */
197 * Function: markSignalHandlers()
199 * Evacuate the handler stack. _Assumes_ that console event delivery
200 * has already been blocked.
202 void markSignalHandlers (evac_fn evac STG_UNUSED)
204 // nothing to mark; the console handler is a StablePtr which is
205 // already treated as a root by the GC.
210 * Function: generic_handler()
212 * Local function which handles incoming console event (done in a sep OS thread),
213 * recording the event in stg_pending_events.
215 static BOOL WINAPI generic_handler(DWORD dwCtrlType)
217 /* Ultra-simple -- up the counter + signal a switch. */
219 case CTRL_CLOSE_EVENT:
220 /* Don't support the delivery of this event; if we
221 * indicate that we've handled it here and the Haskell handler
222 * doesn't take proper action (e.g., terminate the OS process),
223 * the user of the app will be unable to kill/close it. Not
224 * good, so disable the delivery for now.
228 if (!deliver_event) return TRUE;
230 #if defined(THREADED_RTS)
231 sendIOManagerEvent((StgWord8) ((dwCtrlType<<1) | 1));
233 if ( stg_pending_events < N_PENDING_EVENTS ) {
234 stg_pending_buf[stg_pending_events] = dwCtrlType;
235 stg_pending_events++;
244 * Function: rts_InstallConsoleEvent()
246 * Install/remove a console event handler.
249 rts_InstallConsoleEvent(int action, StgStablePtr *handler)
251 StgInt previous_hdlr = console_handler;
255 console_handler = STG_SIG_IGN;
256 if ( !SetConsoleCtrlHandler(NULL, TRUE) ) {
257 errorBelch("warning: unable to ignore console events");
261 console_handler = STG_SIG_IGN;
262 if ( !SetConsoleCtrlHandler(NULL, FALSE) ) {
263 errorBelch("warning: unable to restore default console event handling");
268 // handler is stored in an MVar in the threaded RTS
269 console_handler = STG_SIG_HAN;
271 console_handler = (StgInt)*handler;
273 if (previous_hdlr < 0 || previous_hdlr == STG_SIG_HAN) {
274 /* Only install generic_handler() once */
275 if ( !SetConsoleCtrlHandler(generic_handler, TRUE) ) {
276 errorBelch("warning: unable to install console event handler");
282 if (previous_hdlr == STG_SIG_DFL ||
283 previous_hdlr == STG_SIG_IGN ||
284 previous_hdlr == STG_SIG_HAN) {
285 return previous_hdlr;
287 if (handler != NULL) {
288 *handler = (StgStablePtr)previous_hdlr;
295 * Function: rts_HandledConsoleEvent()
297 * Signal that a Haskell console event handler has completed its run.
298 * The explicit notification that a Haskell handler has completed is
299 * required to better handle the delivery of Ctrl-C/Break events whilst
300 * an async worker thread is handling a read request on stdin. The
301 * Win32 console implementation will abort such a read request when Ctrl-C
302 * is delivered. That leaves the worker thread in a bind: should it
303 * abandon the request (the Haskell thread reading from stdin has been
304 * thrown an exception to signal the delivery of Ctrl-C & hence have
305 * aborted the I/O request) or simply ignore the aborted read and retry?
306 * (the Haskell thread reading from stdin isn't concerned with the
307 * delivery and handling of Ctrl-C.) With both scenarios being
308 * possible, the worker thread needs to be told -- that is, did the
309 * console event handler cause the IO request to be abandoned?
313 rts_ConsoleHandlerDone (int ev USED_IF_NOT_THREADS)
315 #if !defined(THREADED_RTS)
316 if ( (DWORD)ev == CTRL_BREAK_EVENT ||
317 (DWORD)ev == CTRL_C_EVENT ) {
318 /* only these two cause stdin system calls to abort.. */
319 SetEvent(hConsoleEvent); /* event is manual-reset */
320 Sleep(0); /* yield */
321 ResetEvent(hConsoleEvent); /* turn it back off again */
322 // SDM: yeuch, this can't possibly work reliably.
323 // I'm not having it in THREADED_RTS.
328 #if !defined(THREADED_RTS)
330 * Function: rts_waitConsoleHandlerCompletion()
332 * Esoteric entry point used by worker thread that got woken
333 * up as part Ctrl-C delivery.
336 rts_waitConsoleHandlerCompletion()
338 /* As long as the worker doesn't need to do a multiple wait,
339 * let's keep this HANDLE private to this 'module'.
341 return (WaitForSingleObject(hConsoleEvent, INFINITE) == WAIT_OBJECT_0);