[project @ 2004-08-13 13:04:50 by simonmar]

[ghc-hetmet.git] / ghc / rts / Signals.c

diff --git a/ghc/rts/Signals.c b/ghc/rts/Signals.c
index 6d9ea44..4d76b11 100644 (file)
--- a/ghc/rts/Signals.c
+++ b/ghc/rts/Signals.c
@@ -1,5 +1,5 @@
 /* -----------------------------------------------------------------------------
 /* -----------------------------------------------------------------------------

- * $Id: Signals.c,v 1.4 1999/02/05 16:02:54 simonm Exp $
+ * $Id: Signals.c,v 1.41 2004/08/13 13:10:44 simonmar Exp $

  *
  * (c) The GHC Team, 1998-1999
  *
  *
  * (c) The GHC Team, 1998-1999
  *

@@ -7,71 +7,140 @@
  *
  * ---------------------------------------------------------------------------*/
 
  *
  * ---------------------------------------------------------------------------*/
 

+/* This is non-Posix-compliant.
+   #include "PosixSource.h" 
+*/

 #include "Rts.h"
 #include "SchedAPI.h"
 #include "Rts.h"
 #include "SchedAPI.h"

+#include "Schedule.h"

 #include "Signals.h"
 #include "RtsUtils.h"
 #include "RtsFlags.h"
 #include "Signals.h"
 #include "RtsUtils.h"
 #include "RtsFlags.h"

-#include "StablePriv.h"

 
 

-#ifndef PAR
+#ifdef alpha_TARGET_ARCH
+# if defined(linux_TARGET_OS)
+#  include <asm/fpu.h>
+# else
+#  include <machine/fpu.h>
+# endif
+#endif
+
+#ifdef HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+
+#ifdef HAVE_SIGNAL_H
+# include <signal.h>
+#endif
+
+#include <stdlib.h>

 
 

+/* This curious flag is provided for the benefit of the Haskell binding
+ * to POSIX.1 to control whether or not to include SA_NOCLDSTOP when
+ * installing a SIGCHLD handler. 
+ * 
+ */
+StgInt nocldstop = 0;
+
+#if defined(RTS_USER_SIGNALS)
+
+/* SUP: The type of handlers is a little bit, well, doubtful... */

 static StgInt *handlers = NULL; /* Dynamically grown array of signal handlers */
 static StgInt nHandlers = 0;    /* Size of handlers array */
 
 static StgInt *handlers = NULL; /* Dynamically grown array of signal handlers */
 static StgInt nHandlers = 0;    /* Size of handlers array */
 

+static nat n_haskell_handlers = 0;
+

 #define N_PENDING_HANDLERS 16
 
 StgPtr pending_handler_buf[N_PENDING_HANDLERS];
 StgPtr *next_pending_handler = pending_handler_buf;
 
 #define N_PENDING_HANDLERS 16
 
 StgPtr pending_handler_buf[N_PENDING_HANDLERS];
 StgPtr *next_pending_handler = pending_handler_buf;
 

-StgInt nocldstop = 0;
+#ifdef RTS_SUPPORTS_THREADS
+pthread_t signalHandlingThread;
+#endif
+
+       // Handle all signals in the current thread.
+       // Called from Capability.c whenever the main capability is granted to a thread
+       // and in installDefaultHandlers
+void
+handleSignalsInThisThread()
+{
+#ifdef RTS_SUPPORTS_THREADS
+    signalHandlingThread = pthread_self();
+#endif
+}
+

 
 /* -----------------------------------------------------------------------------
 
 /* -----------------------------------------------------------------------------

-   Allocate/resize the table of signal handlers.
-   -------------------------------------------------------------------------- */
+ * Allocate/resize the table of signal handlers.
+ * -------------------------------------------------------------------------- */

 
 static void
 more_handlers(I_ sig)
 {
 
 static void
 more_handlers(I_ sig)
 {

-    I_ i;
+    StgInt i;

 
     if (sig < nHandlers)
        return;
 
     if (handlers == NULL)
 
     if (sig < nHandlers)
        return;
 
     if (handlers == NULL)

-       handlers = (I_ *) malloc((sig + 1) * sizeof(I_));
+       handlers = (StgInt *)stgMallocBytes((sig + 1) * sizeof(StgInt), "more_handlers");

     else
     else

-       handlers = (I_ *) realloc(handlers, (sig + 1) * sizeof(I_));
+       handlers = (StgInt *)stgReallocBytes(handlers, (sig + 1) * sizeof(StgInt), "more_handlers");

 
 

-    if (handlers == NULL) {
-       fflush(stdout);
-       fprintf(stderr, "VM exhausted (in more_handlers)\n");
-       exit(EXIT_FAILURE);
-    }

     for(i = nHandlers; i <= sig; i++)
     for(i = nHandlers; i <= sig; i++)

-       /* Fill in the new slots with default actions */
+       // Fill in the new slots with default actions

        handlers[i] = STG_SIG_DFL;
 
     nHandlers = sig + 1;
 }
 
 /* -----------------------------------------------------------------------------
        handlers[i] = STG_SIG_DFL;
 
     nHandlers = sig + 1;
 }
 
 /* -----------------------------------------------------------------------------

-   Low-level signal handler
+ * SIGCONT handler
+ *
+ * It seems that shells tend to put stdin back into blocking mode
+ * following a suspend/resume of the process.  Here we arrange to put
+ * it back into non-blocking mode.  We don't do anything to
+ * stdout/stderr because these handles don't get put into non-blocking
+ * mode at all - see the comments on stdout/stderr in PrelHandle.hsc.
+ * -------------------------------------------------------------------------- */

 
 

-   Places the requested handler on a stack of pending handlers to be
-   started up at the next context switch.
-   -------------------------------------------------------------------------- */
+static void
+cont_handler(int sig STG_UNUSED)
+{
+    setNonBlockingFd(0);
+}
+
+/* -----------------------------------------------------------------------------
+ * Low-level signal handler
+ *
+ * Places the requested handler on a stack of pending handlers to be
+ * started up at the next context switch.
+ * -------------------------------------------------------------------------- */

 
 static void
 generic_handler(int sig)
 {
     sigset_t signals;
 
 
 static void
 generic_handler(int sig)
 {
     sigset_t signals;
 

+#if defined(THREADED_RTS)
+       // Make the thread that currently holds the main capability
+       // handle the signal.
+       // This makes sure that awaitEvent() is interrupted
+       // and it (hopefully) prevents race conditions
+       // (signal handlers are not atomic with respect to other threads)
+
+    if(pthread_self() != signalHandlingThread) {
+        pthread_kill(signalHandlingThread, sig);
+        return;
+    }
+#endif
+

     /* Can't call allocate from here.  Probably can't call malloc
        either.  However, we have to schedule a new thread somehow.
 
        It's probably ok to request a context switch and allow the
     /* Can't call allocate from here.  Probably can't call malloc
        either.  However, we have to schedule a new thread somehow.
 
        It's probably ok to request a context switch and allow the

-       scheduler to  start the handler thread, but how to we
+       scheduler to  start the handler thread, but how do we

        communicate this to the scheduler?
 
        We need some kind of locking, but with low overhead (i.e. no
        communicate this to the scheduler?
 
        We need some kind of locking, but with low overhead (i.e. no

@@ -95,22 +164,30 @@ generic_handler(int sig)
        circumstances, depending on the signal.  
     */
 
        circumstances, depending on the signal.  
     */
 

-    *next_pending_handler++ = deRefStablePtr(handlers[sig]);
+    *next_pending_handler++ = deRefStablePtr((StgStablePtr)handlers[sig]);

 
 

-    /* stack full? */
+    // stack full?

     if (next_pending_handler == &pending_handler_buf[N_PENDING_HANDLERS]) {
     if (next_pending_handler == &pending_handler_buf[N_PENDING_HANDLERS]) {

-      barf("too many pending signals");
+       prog_belch("too many pending signals");
+       stg_exit(EXIT_FAILURE);

     }
     
     }
     

-    /* re-establish the signal handler, and carry on */
+    // re-establish the signal handler, and carry on

     sigemptyset(&signals);
     sigaddset(&signals, sig);
     sigprocmask(SIG_UNBLOCK, &signals, NULL);
     sigemptyset(&signals);
     sigaddset(&signals, sig);
     sigprocmask(SIG_UNBLOCK, &signals, NULL);

+
+    // *always* do the SIGCONT handler, even if the user overrides it.
+    if (sig == SIGCONT) {
+       cont_handler(sig);
+    }
+
+    context_switch = 1;

 }
 
 /* -----------------------------------------------------------------------------
 }
 
 /* -----------------------------------------------------------------------------

-   Blocking/Unblocking of the user signals
-   -------------------------------------------------------------------------- */
+ * Blocking/Unblocking of the user signals
+ * -------------------------------------------------------------------------- */

 
 static sigset_t userSignals;
 static sigset_t savedSignals;
 
 static sigset_t userSignals;
 static sigset_t savedSignals;

@@ -124,7 +201,7 @@ initUserSignals(void)
 void
 blockUserSignals(void)
 {
 void
 blockUserSignals(void)
 {

-    sigprocmask(SIG_SETMASK, &userSignals, &savedSignals);
+    sigprocmask(SIG_BLOCK, &userSignals, &savedSignals);

 }
 
 void
 }
 
 void

@@ -133,28 +210,44 @@ unblockUserSignals(void)
     sigprocmask(SIG_SETMASK, &savedSignals, NULL);
 }
 
     sigprocmask(SIG_SETMASK, &savedSignals, NULL);
 }
 

+rtsBool
+anyUserHandlers(void)
+{
+    return n_haskell_handlers != 0;
+}
+
+void
+awaitUserSignals(void)
+{
+    while (!signals_pending() && !interrupted) {
+       pause();
+    }
+}

 
 /* -----------------------------------------------------------------------------
 
 /* -----------------------------------------------------------------------------

-   Install a Haskell signal handler.
-   -------------------------------------------------------------------------- */
+ * Install a Haskell signal handler.
+ * -------------------------------------------------------------------------- */

 
 

-StgInt 
-sig_install(StgInt sig, StgInt spi, StgStablePtr handler, sigset_t *mask)
+int
+stg_sig_install(int sig, int spi, StgStablePtr *handler, void *mask)

 {
 {

-    sigset_t signals;
+    sigset_t signals, osignals;

     struct sigaction action;
     StgInt previous_spi;
 
     struct sigaction action;
     StgInt previous_spi;
 

-    /* Block the signal until we figure out what to do */
-    /* Count on this to fail if the signal number is invalid */
-    if(sig < 0 || sigemptyset(&signals) || sigaddset(&signals, sig) ||
-       sigprocmask(SIG_BLOCK, &signals, NULL))
-      return STG_SIG_ERR;
-
+    // Block the signal until we figure out what to do
+    // Count on this to fail if the signal number is invalid
+    if (sig < 0 || sigemptyset(&signals) ||
+       sigaddset(&signals, sig) || sigprocmask(SIG_BLOCK, &signals, &osignals)) {
+       return STG_SIG_ERR;
+    }
+    

     more_handlers(sig);
 
     previous_spi = handlers[sig];
 
     more_handlers(sig);
 
     previous_spi = handlers[sig];
 

+    action.sa_flags = 0;
+    

     switch(spi) {
     case STG_SIG_IGN:
        handlers[sig] = STG_SIG_IGN;
     switch(spi) {
     case STG_SIG_IGN:
        handlers[sig] = STG_SIG_IGN;

@@ -167,43 +260,55 @@ sig_install(StgInt sig, StgInt spi, StgStablePtr handler, sigset_t *mask)
        sigdelset(&userSignals, sig);
         action.sa_handler = SIG_DFL;
        break;
        sigdelset(&userSignals, sig);
         action.sa_handler = SIG_DFL;
        break;

+

     case STG_SIG_HAN:
     case STG_SIG_HAN:

-       handlers[sig] = (I_)handler;
+    case STG_SIG_RST:
+       handlers[sig] = (StgInt)*handler;

        sigaddset(&userSignals, sig);
        action.sa_handler = generic_handler;
        sigaddset(&userSignals, sig);
        action.sa_handler = generic_handler;

+       if (spi == STG_SIG_RST) {
+           action.sa_flags = SA_RESETHAND;
+       }
+       n_haskell_handlers++;

        break;
        break;

+

     default:
     default:

-        barf("sig_install: bad spi");
+        barf("stg_sig_install: bad spi");

     }
 
     }
 

-    if (mask != 0)
-        action.sa_mask = *mask;
+    if (mask != NULL)
+        action.sa_mask = *(sigset_t *)mask;

     else
        sigemptyset(&action.sa_mask);
 
     else
        sigemptyset(&action.sa_mask);
 

-    action.sa_flags = sig == SIGCHLD && nocldstop ? SA_NOCLDSTOP : 0;
+    action.sa_flags |= sig == SIGCHLD && nocldstop ? SA_NOCLDSTOP : 0;

 
     if (sigaction(sig, &action, NULL) || 
 
     if (sigaction(sig, &action, NULL) || 

-       sigprocmask(SIG_UNBLOCK, &signals, NULL)) 
+       sigprocmask(SIG_SETMASK, &osignals, NULL)) 

     {
     {

-      /* need to return an error code, so avoid a stable pointer leak
-       * by freeing the previous handler if there was one.
-       */       
-      if (previous_spi >= 0) {
-         freeStablePtr(handlers[sig]);
-      }
-      return STG_SIG_ERR;
+       // need to return an error code, so avoid a stable pointer leak
+       // by freeing the previous handler if there was one.
+       if (previous_spi >= 0) {
+           freeStablePtr(stgCast(StgStablePtr,handlers[sig]));
+           n_haskell_handlers--;
+       }
+       return STG_SIG_ERR;

     }
 
     }
 

-    return previous_spi;
+    if (previous_spi == STG_SIG_DFL || previous_spi == STG_SIG_IGN
+       || previous_spi == STG_SIG_ERR) {
+       return previous_spi;
+    } else {
+       *handler = (StgStablePtr)previous_spi;
+       return STG_SIG_HAN;
+    }

 }
 
 /* -----------------------------------------------------------------------------
 }
 
 /* -----------------------------------------------------------------------------

-   Creating new threads for the pending signal handlers.
-   -------------------------------------------------------------------------- */
-
+ * Creating new threads for the pending signal handlers.
+ * -------------------------------------------------------------------------- */

 void
 void

-start_signal_handlers(void)
+startSignalHandlers(void)

 {
   blockUserSignals();
   
 {
   blockUserSignals();
   

@@ -211,29 +316,163 @@ start_signal_handlers(void)
 
     next_pending_handler--;
 
 
     next_pending_handler--;
 

-    /* create*Thread  puts the thread on the head of the runnable
-     * queue, hence it will be run next.  Poor man's priority
-     * scheduling.
-     */
-    createIOThread(RtsFlags.GcFlags.initialStkSize, 
-                  (StgClosure *) *next_pending_handler);
+    scheduleThread(
+       createIOThread(RtsFlags.GcFlags.initialStkSize, 
+                     (StgClosure *) *next_pending_handler));

   }
 
   unblockUserSignals();
 }
 
   }
 
   unblockUserSignals();
 }
 

-#else /* PAR */
+/* ----------------------------------------------------------------------------
+ * Mark signal handlers during GC.
+ *
+ * We do this rather than trying to start all the signal handlers
+ * prior to GC, because that requires extra heap for the new threads.
+ * Signals must be blocked (see blockUserSignals() above) during GC to
+ * avoid race conditions.
+ * -------------------------------------------------------------------------- */
+
+void
+markSignalHandlers (evac_fn evac)
+{
+    StgPtr *p;
+
+    p = next_pending_handler;
+    while (p != pending_handler_buf) {
+       p--;
+       evac((StgClosure **)p);
+    }
+}
+
+#else /* !RTS_USER_SIGNALS */

 StgInt 
 StgInt 

-sig_install(StgInt sig, StgInt spi, StgStablePtr handler, sigset_t *mask)
+stg_sig_install(StgInt sig STG_UNUSED,
+               StgInt spi STG_UNUSED,
+               StgStablePtr* handler STG_UNUSED,
+               void* mask STG_UNUSED)

 {
 {

-    fflush(stdout);
-    fprintf(stderr,
-           "No signal handling support in a parallel implementation.\n");
-    exit(EXIT_FAILURE);
+  //barf("User signals not supported");
+  return STG_SIG_DFL;

 }
 
 }
 

-void
-start_signal_handlers(void)
+#endif
+
+#if defined(RTS_USER_SIGNALS)
+/* -----------------------------------------------------------------------------
+ * SIGINT handler.
+ *
+ * We like to shutdown nicely after receiving a SIGINT, write out the
+ * stats, write profiling info, close open files and flush buffers etc.
+ * -------------------------------------------------------------------------- */
+#ifdef SMP
+pthread_t startup_guy;
+#endif
+
+static void
+shutdown_handler(int sig STG_UNUSED)

 {
 {

+#ifdef SMP
+    // if I'm a worker thread, send this signal to the guy who
+    // originally called startupHaskell().  Since we're handling
+    // the signal, it won't be a "send to all threads" type of signal
+    // (according to the POSIX threads spec).
+    if (pthread_self() != startup_guy) {
+       pthread_kill(startup_guy, sig);
+       return;
+    }
+    // ToDo: The code for the threaded RTS below does something very
+    // similar. Maybe the SMP special case is not needed
+    // -- Wolfgang Thaller
+#elif defined(THREADED_RTS)
+       // Make the thread that currently holds the main capability
+       // handle the signal.
+       // This makes sure that awaitEvent() is interrupted
+    if(pthread_self() != signalHandlingThread) {
+        pthread_kill(signalHandlingThread, sig);
+        return;
+    }
+#endif
+
+    // 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.
+    if (interrupted) {
+       stg_exit(EXIT_INTERRUPTED);
+    } else {
+       interruptStgRts();
+    }

 }
 }

+
+/* -----------------------------------------------------------------------------
+ * Install default signal handlers.
+ *
+ * The RTS installs a default signal handler for catching
+ * SIGINT, so that we can perform an orderly shutdown.
+ *
+ * Haskell code may install their own SIGINT handler, which is
+ * fine, provided they're so kind as to put back the old one
+ * when they de-install.
+ *
+ * In addition to handling SIGINT, the RTS also handles SIGFPE
+ * by ignoring it.  Apparently IEEE requires floating-point
+ * exceptions to be ignored by default, but alpha-dec-osf3
+ * doesn't seem to do so.
+ * -------------------------------------------------------------------------- */
+void
+initDefaultHandlers()
+{
+    struct sigaction action,oact;
+
+#ifdef SMP
+    startup_guy = pthread_self();

 #endif
 #endif

+#ifdef RTS_SUPPORTS_THREADS
+    handleSignalsInThisThread();
+#endif
+
+    // install the SIGINT handler
+    action.sa_handler = shutdown_handler;
+    sigemptyset(&action.sa_mask);
+    action.sa_flags = 0;
+    if (sigaction(SIGINT, &action, &oact) != 0) {
+       prog_belch("warning: failed to install SIGINT handler");
+    }
+
+#if defined(HAVE_SIGINTERRUPT)
+    siginterrupt(SIGINT, 1);   // isn't this the default? --SDM
+#endif
+
+    // install the SIGCONT handler
+    action.sa_handler = cont_handler;
+    sigemptyset(&action.sa_mask);
+    action.sa_flags = 0;
+    if (sigaction(SIGCONT, &action, &oact) != 0) {
+       prog_belch("warning: failed to install SIGCONT handler");
+    }
+
+    // install the SIGFPE handler
+
+    // In addition to handling SIGINT, also handle SIGFPE by ignoring it.
+    // Apparently IEEE requires floating-point exceptions to be ignored by
+    // default, but alpha-dec-osf3 doesn't seem to do so.
+
+    // Commented out by SDM 2/7/2002: this causes an infinite loop on
+    // some architectures when an integer division by zero occurs: we
+    // don't recover from the floating point exception, and the
+    // program just generates another one immediately.
+#if 0
+    action.sa_handler = SIG_IGN;
+    sigemptyset(&action.sa_mask);
+    action.sa_flags = 0;
+    if (sigaction(SIGFPE, &action, &oact) != 0) {
+       prog_belch("warning: failed to install SIGFPE handler");
+    }
+#endif
+
+#ifdef alpha_TARGET_ARCH
+    ieee_set_fp_control(0);
+#endif
+}
+
+#endif /* RTS_USER_SIGNALS */