accomodate signal-handler calls from multiple threads

svn: r9225

src/mred/mred.cxx

@@ -1655,6 +1655,7 @@ void wxDoEvents()
 								  c->main_cells,
 								  c->main_break_cell,
 								  NULL, 0);
+      scheme_set_break_main_target(user_main_thread);
       cp = scheme_intern_symbol("mred");
       user_main_thread->name = cp;
     }
@@ -1778,7 +1779,7 @@ static void MrEdSleep(float secs, void *fds)
 #ifdef mred_BREAK_HANDLER
 static void user_break_hit(int ignore)
 {
-  scheme_break_thread(user_main_thread);
+  scheme_break_main_thread();
   scheme_signal_received();
 
 #  ifdef SIGSET_NEEDS_REINSTALL
@@ -2369,7 +2370,7 @@ void IOFrame::OnMenuCommand(long id)
   else if (id == 81)
     media->Paste();
   else if (id == 83)
-    scheme_break_thread(user_main_thread);
+    scheme_break_main_thread();
   else if (id == 77)
     if (OnClose())
       Show(FALSE);
@@ -2448,7 +2449,7 @@ static Bool RecordInput(void *m, wxEvent *event, void *data)
 
 static Bool SendBreak(void *m, wxEvent *event, void *data)
 {
-  scheme_break_thread(user_main_thread);
+  scheme_break_main_thread();
   return TRUE;
 }
 

src/mzscheme/include/mzscheme.exp

@@ -26,6 +26,8 @@ scheme_thread
 scheme_thread_w_details
 scheme_kill_thread
 scheme_break_thread
+scheme_break_main_thread
+scheme_set_break_main_target
 scheme_thread_block
 scheme_thread_block_enable_break
 scheme_swap_thread

src/mzscheme/include/mzscheme3m.exp

@@ -26,6 +26,8 @@ scheme_thread
 scheme_thread_w_details
 scheme_kill_thread
 scheme_break_thread
+scheme_break_main_thread
+scheme_set_break_main_target
 scheme_thread_block
 scheme_thread_block_enable_break
 scheme_swap_thread

src/mzscheme/include/mzwin.def

@@ -28,6 +28,8 @@ EXPORTS
  scheme_thread_w_details
  scheme_kill_thread
  scheme_break_thread
+ scheme_break_main_thread
+ scheme_set_break_main_target
  scheme_thread_block
  scheme_thread_block_enable_break
  scheme_swap_thread

src/mzscheme/include/mzwin3m.def

@@ -28,6 +28,8 @@ EXPORTS
  scheme_thread_w_details
  scheme_kill_thread
  scheme_break_thread
+ scheme_break_main_thread
+ scheme_set_break_main_target
  scheme_thread_block
  scheme_thread_block_enable_break
  scheme_swap_thread

src/mzscheme/main.c

@@ -169,7 +169,7 @@ extern Scheme_Object *scheme_initialize(Scheme_Env *env);
 
 static void user_break_hit(int ignore)
 {
-  scheme_break_thread(NULL);
+  scheme_break_main_thread();
   scheme_signal_received();
 
 #  ifdef SIGSET_NEEDS_REINSTALL

src/mzscheme/src/port.c

@@ -6458,38 +6458,7 @@ void scheme_block_child_signals(int block)
 
 static void child_done(int ingored)
 {
-  pid_t result;
-  int status;
-  System_Child *sc, *prev;
-
-  do {
-    do {
-      result = WAITANY(&status);
-    } while ((result == -1) && (errno == EINTR));
-
-    if (result > 0) {
-      if (WIFEXITED(status))
-	status = WEXITSTATUS(status);
-      else
-	status = MZ_FAILURE_STATUS;
-
-      prev = NULL;
-      for (sc = scheme_system_children; sc; prev = sc, sc = sc->next) {
-	if (sc->id == result) {
-          sc->done = 1;
-	  sc->status = status;
-
-	  if (prev) {
-	    prev->next = sc->next;
-	  } else
-	    scheme_system_children = sc->next;
-
-	  scheme_signal_received();
-	  break;
-	}
-      }
-    }
-  } while (result > 0);
+  scheme_signal_received();
 
 # ifdef SIGSET_NEEDS_REINSTALL
   MZ_SIGSET(SIGCHLD, child_done);
@@ -6514,6 +6483,43 @@ static void init_sigchld(void)
   }
 }
 
+void scheme_check_child_done()
+{
+  pid_t result;
+  int status;
+  System_Child *sc, *prev;
+
+  if (scheme_system_children) {
+    do {
+      do {
+        result = WAITANY(&status);
+      } while ((result == -1) && (errno == EINTR));
+
+      if (result > 0) {
+        if (WIFEXITED(status))
+          status = WEXITSTATUS(status);
+        else
+          status = MZ_FAILURE_STATUS;
+
+        prev = NULL;
+        for (sc = scheme_system_children; sc; prev = sc, sc = sc->next) {
+          if (sc->id == result) {
+            sc->done = 1;
+            sc->status = status;
+
+            if (prev) {
+              prev->next = sc->next;
+            } else
+              scheme_system_children = sc->next;
+            
+            break;
+          }
+        }
+      }
+    } while (result > 0);
+  }
+}
+
 #endif
 
 /*========================================================================*/

src/mzscheme/src/schemef.h

@@ -92,6 +92,8 @@ MZ_EXTERN Scheme_Object *scheme_thread_w_details(Scheme_Object *thunk,
 						 int suspend_to_kill);
 MZ_EXTERN void scheme_kill_thread(Scheme_Thread *p);
 MZ_EXTERN void scheme_break_thread(Scheme_Thread *p);
+MZ_EXTERN void scheme_break_main_thread();
+MZ_EXTERN void scheme_set_break_main_target(Scheme_Thread *p);
 
 MZ_EXTERN void scheme_thread_block(float sleep_time);
 MZ_EXTERN void scheme_thread_block_enable_break(float sleep_time, int enable);

src/mzscheme/src/schemex.h

@@ -74,6 +74,8 @@ Scheme_Object *(*scheme_thread_w_details)(Scheme_Object *thunk,
 						 int suspend_to_kill);
 void (*scheme_kill_thread)(Scheme_Thread *p);
 void (*scheme_break_thread)(Scheme_Thread *p);
+void (*scheme_break_main_thread)();
+void (*scheme_set_break_main_target)(Scheme_Thread *p);
 void (*scheme_thread_block)(float sleep_time);
 void (*scheme_thread_block_enable_break)(float sleep_time, int enable);
 void (*scheme_swap_thread)(Scheme_Thread *process);

src/mzscheme/src/schemex.inc

@@ -34,6 +34,8 @@
   scheme_extension_table->scheme_thread_w_details = scheme_thread_w_details;
   scheme_extension_table->scheme_kill_thread = scheme_kill_thread;
   scheme_extension_table->scheme_break_thread = scheme_break_thread;
+  scheme_extension_table->scheme_break_main_thread = scheme_break_main_thread;
+  scheme_extension_table->scheme_set_break_main_target = scheme_set_break_main_target;
   scheme_extension_table->scheme_thread_block = scheme_thread_block;
   scheme_extension_table->scheme_thread_block_enable_break = scheme_thread_block_enable_break;
   scheme_extension_table->scheme_swap_thread = scheme_swap_thread;

src/mzscheme/src/schemexm.h

@@ -34,6 +34,8 @@
 #define scheme_thread_w_details (scheme_extension_table->scheme_thread_w_details)
 #define scheme_kill_thread (scheme_extension_table->scheme_kill_thread)
 #define scheme_break_thread (scheme_extension_table->scheme_break_thread)
+#define scheme_break_main_thread (scheme_extension_table->scheme_break_main_thread)
+#define scheme_set_break_main_target (scheme_extension_table->scheme_set_break_main_target)
 #define scheme_thread_block (scheme_extension_table->scheme_thread_block)
 #define scheme_thread_block_enable_break (scheme_extension_table->scheme_thread_block_enable_break)
 #define scheme_swap_thread (scheme_extension_table->scheme_swap_thread)

src/mzscheme/src/thread.c

@@ -95,6 +95,10 @@ extern HANDLE scheme_break_semaphore;
 
 #include "schfd.h"
 
+#if defined(UNIX_PROCESSES)
+extern void scheme_check_child_done();
+#endif
+
 #define DEFAULT_INIT_STACK_SIZE 1000
 #define MAX_INIT_STACK_SIZE 100000
 
@@ -119,6 +123,8 @@ extern void scheme_gmp_tls_unload(long *s);
 extern void scheme_gmp_tls_snapshot(long *s, long *save);
 extern void scheme_gmp_tls_restore_snapshot(long *s, long *save, int do_free);
 
+static void check_ready_break();
+
 extern int scheme_num_read_syntax_objects;
 extern int scheme_hash_request_count;
 extern int scheme_hash_iteration_count;
@@ -210,7 +216,8 @@ extern MZ_DLLIMPORT void (*GC_collect_end_callback)(void);
 static void get_ready_for_GC(void);
 static void done_with_GC(void);
 
-static short delay_breaks = 0, delayed_break_ready = 0;
+static volatile short delayed_break_ready = 0;
+static Scheme_Thread *main_break_target_thread;
 
 void (*scheme_sleep)(float seconds, void *fds);
 void (*scheme_notify_multithread)(int on);
@@ -3216,6 +3223,8 @@ Scheme_Object *scheme_call_as_nested_thread(int argc, Scheme_Object *argv[], voi
      GC cleaning for this thread: */
   prepare_this_thread_for_GC(p);
 
+  check_ready_break();
+
   np->nester = p;
   p->nestee = np;
   np->external_break = p->external_break;
@@ -3579,6 +3588,8 @@ void scheme_check_break_now(void)
 {
   Scheme_Thread *p = scheme_current_thread;
 
+  check_ready_break();
+
   if (p->external_break && scheme_can_break(p)) {
     scheme_thread_block_w_thread(0.0, p);
     p->ran_some = 1;
@@ -3726,14 +3737,36 @@ static void exit_or_escape(Scheme_Thread *p)
   select_thread();
 }
 
-void scheme_break_thread(Scheme_Thread *p)
-     /* This function can be called from an interrupt handler. */
+void scheme_break_main_thread()
+/* This function can be called from an interrupt handler. 
+   On some platforms, it will even be called from multiple
+   OS threads. In the case of multiple threads, there's a
+   tiny chance that a single Ctl-C will trigger multiple
+   break exceptions. */
 {
-  if (delay_breaks) {
-    delayed_break_ready = 1;
-    return;
-  }
+  delayed_break_ready = 1;
+}
 
+void scheme_set_break_main_target(Scheme_Thread *p)
+{
+  if (!main_break_target_thread) {
+    REGISTER_SO(main_break_target_thread);
+  }
+  main_break_target_thread = p;
+}
+
+static void check_ready_break()
+{
+  if (delayed_break_ready) {
+    if (scheme_main_thread) {
+      delayed_break_ready = 0;
+      scheme_break_thread(main_break_target_thread);
+    }
+  }
+}
+
+void scheme_break_thread(Scheme_Thread *p)
+{
   if (!p) {
     p = scheme_main_thread;
     if (!p)
@@ -3801,6 +3834,8 @@ void scheme_thread_block(float sleep_time)
 
  start_sleep_check:
 
+  check_ready_break();
+
   if (!p->external_break && !p->next && scheme_check_for_break && scheme_check_for_break())
     p->external_break = 1;
 
@@ -3818,6 +3853,10 @@ void scheme_thread_block(float sleep_time)
   /* Check scheduled_kills early and often. */
   check_scheduled_kills();
 
+#if defined(UNIX_PROCESSES)
+  scheme_check_child_done();
+#endif
+
   if (!do_atomic && (sleep_end >= 0.0)) {
     double msecs = 0.0;
 
@@ -4029,6 +4068,7 @@ void scheme_thread_block(float sleep_time)
   }
 
   /* Check for external break again after swap or sleep */
+  check_ready_break();
   if (p->external_break && !p->suspend_break && scheme_can_break(p)) {
     raise_break(p);
   }
@@ -7108,9 +7148,6 @@ static void get_ready_for_GC()
 #endif
 
   did_gc_count++;
-
-  delayed_break_ready = 0;
-  delay_breaks = 1;
 }
 
 extern int GC_words_allocd;
@@ -7132,10 +7169,6 @@ static void done_with_GC()
   scheme_block_child_signals(0);
 #endif
 
-  delay_breaks = 0;
-  if (delayed_break_ready)
-    scheme_break_thread(NULL);
-
   scheme_total_gc_time += (scheme_get_process_milliseconds() - start_this_gc_time);
 }