Implement Halt Hook (request from Bernd).

C/agc.c

@@ -187,6 +187,7 @@ AtomAdjust(Atom a)
 #define HoldEntryAdjust(P) (P)
 #define CodeCharPAdjust(P) (P)
 #define CodeVoidPAdjust(P) (P)
+#define HaltHookAdjust(P) (P)
 
 #define recompute_mask(dbr)
 

C/c_interface.c

@@ -505,6 +505,7 @@ X_API Term     STD_PROTO(YAP_TermNil,(void));
 X_API int      STD_PROTO(YAP_AtomGetHold,(Atom));
 X_API int      STD_PROTO(YAP_AtomReleaseHold,(Atom));
 X_API Agc_hook STD_PROTO(YAP_AGCRegisterHook,(Agc_hook));
+X_API int      STD_PROTO(YAP_HaltRegisterHook,(HaltHookFunc, void *));
 X_API char    *STD_PROTO(YAP_cwd,(void));
 X_API Term     STD_PROTO(YAP_OpenList,(int));
 X_API Term     STD_PROTO(YAP_ExtendList,(Term, Term));
@@ -2957,6 +2958,12 @@ YAP_AGCRegisterHook(Agc_hook hook)
   return old;
 } 
 
+X_API int
+YAP_HaltRegisterHook(HaltHookFunc hook, void * closure)
+{
+  return Yap_HaltRegisterHook(hook, closure);
+} 
+
 X_API char *
 YAP_cwd(void)
 {

C/init.c

@@ -1333,6 +1333,33 @@ Yap_InitWorkspace(UInt Heap, UInt Stack, UInt Trail, UInt Atts, UInt max_table_s
   }
 }
 
+int
+Yap_HaltRegisterHook (HaltHookFunc f, void * env)
+{
+  struct halt_hook *h;
+
+  if (!(h = (struct halt_hook *)Yap_AllocCodeSpace(sizeof(struct halt_hook))))
+    return FALSE;
+  h->environment = env;
+  h->hook = f;
+  LOCK(BGL);
+  h->next = Yap_HaltHooks;
+  Yap_HaltHooks = h;
+  UNLOCK(BGL);
+  return TRUE;
+}
+
+static void
+run_halt_hooks(int code)
+{
+  struct halt_hook *hooke = Yap_HaltHooks;
+
+  while (hooke) {
+    hooke->hook(code, hooke->environment);
+    hooke = hooke->next;
+  }
+}
+
 void
 Yap_exit (int value)
 {
@@ -1340,6 +1367,7 @@ Yap_exit (int value)
   unmap_memory();
 #endif /* YAPOR */
 
+  if (! (Yap_PrologMode & BootMode) ) {
 #ifdef LOW_PROF
     remove("PROFPREDS");
     remove("PROFILING");
@@ -1347,8 +1375,9 @@ Yap_exit (int value)
 #if defined MYDDAS_MYSQL || defined MYDDAS_ODBC
     Yap_MYDDAS_delete_all_myddas_structs();
 #endif
-  if (! (Yap_PrologMode & BootMode) )
+    run_halt_hooks(value);
     Yap_ShutdownLoadForeign();
+  }
   exit(value);
 }
 

H/YapHeap.h

@@ -62,6 +62,16 @@ typedef struct gc_ma_hash_entry_struct {
   struct gc_ma_hash_entry_struct *next;
 } gc_ma_hash_entry;
 
+typedef void (*HaltHookFunc)(int, void *);
+
+typedef struct halt_hook {
+  void * environment;
+  HaltHookFunc hook;
+  struct halt_hook *next;
+} halt_hook_entry;
+
+int	STD_PROTO(Yap_HaltRegisterHook,(HaltHookFunc, void *));
+
 typedef struct atom_hash_entry {
 #if defined(YAPOR) || defined(THREADS)
   rwlock_t AERWLock;

H/dhstruct.h

@@ -263,6 +263,8 @@
 
 #define Stream Yap_heap_regs->yap_streams
 
+#define Yap_HaltHooks Yap_heap_regs->yap_halt_hook
+
 #define NOfFileAliases Yap_heap_regs->n_of_file_aliases
 #define SzOfFileAliases Yap_heap_regs->sz_of_file_aliases
 #define FileAliases Yap_heap_regs->file_aliases

H/hstruct.h

@@ -263,6 +263,8 @@
 
   struct stream_desc  *yap_streams;
 
+  struct halt_hook  *yap_halt_hook;
+
   UInt  n_of_file_aliases;
   UInt  sz_of_file_aliases;
   struct AliasDescS  *file_aliases;

H/ihstruct.h

@@ -263,6 +263,8 @@
 
   Yap_heap_regs->yap_streams = NULL;
 
+  Yap_heap_regs->yap_halt_hook = NULL;
+
   Yap_heap_regs->n_of_file_aliases = 0;
   Yap_heap_regs->sz_of_file_aliases = 0;
   Yap_heap_regs->file_aliases = NULL;

H/rheap.h

@@ -899,6 +899,18 @@ RestoreDBErasedIList(void)
   }
 }
 
+static void
+RestoreHaltHooks(void)
+{
+  struct halt_hook *hooke = Yap_HaltHooks = HaltHookAdjust(Yap_HaltHooks);
+
+  while (hooke) {
+    hooke->next = HaltHookAdjust(hooke->next);
+    hooke = hooke->next;
+  }
+}
+
+
 static void
 RestoreStreams(void)
 {

H/rhstruct.h

@@ -263,6 +263,8 @@
 
   RestoreStreams();
 
+  RestoreHaltHooks();
+
 
 
   RestoreAliases();

H/sshift.h

@@ -610,7 +610,15 @@ CodeVoidPAdjust (void * addr)
   return addr + HDiff;
 }
 
+inline EXTERN struct halt_hook *HaltHookAdjust (struct halt_hook *);
 
+inline EXTERN struct halt_hook *
+HaltHookAdjust (struct halt_hook * addr)
+{
+  if (!addr)
+    return NULL;
+  return  (struct halt_hook *) (CharP (addr) + HDiff);
+}
 
 inline EXTERN BlockHeader *BlockAdjust (BlockHeader *);
 
@@ -620,8 +628,6 @@ BlockAdjust (BlockHeader * addr)
   return (BlockHeader *) ((BlockHeader *) (CharP (addr) + HDiff));
 }
 
-
-
 inline EXTERN yamop *PtoOpAdjust (yamop *);
 
 inline EXTERN yamop *

docs/yap.tex

@@ -1384,7 +1384,7 @@ anonymous variables.
 
 Punctuation tokens consist of one of the following characters:
 @example
-@center ( ) , [ ] @{ @} |
+( ) , [ ] @{ @} |
 @end example
 
 These characters are used to group terms.
@@ -3346,7 +3346,7 @@ Also refer to @code{copy_term/2}.
 True when @var{List} is a proper list. That is, @var{List}
 is bound to the empty list (nil) or a term with functor '.' and arity 2.
 
-@item ?@var{Term1} =@= ?@var{Term2}
+@item ?@var{Term1} =@@= ?@var{Term2}
 @findex  =@=/2
 @syindex =@=/2
 @cnindex =@=/2
@@ -16695,6 +16695,14 @@ only two boolean flags are accepted: @code{YAPC_ENABLE_GC} and
 @code{YAPC_ENABLE_AGC}.  The first enables/disables the standard garbage
 collector, the second does the same for the atom garbage collector.`
 
+@item  @code{int} YAP_HaltRegisterHook(@code{YAP_halt_hook f, void *closure})
+@findex YAP_HaltRegisterHook (C-Interface function)
+
+Register the function @var{f} to be called if YAP is halted. The
+function is called with two arguments: the exit code of the process (@code{0}
+if this cannot be determined on your operating system) and the closure
+argument @var{closure}. 
+@c See also @code{at_halt/1}.
 @end table
 
 

include/YapInterface.h

@@ -470,6 +470,9 @@ extern X_API int  PROTO(YAP_AtomReleaseHold,(YAP_Atom));
 /*  void  YAP_AtomReleaseHold(YAP_Atom)  */
 extern X_API YAP_agc_hook  PROTO(YAP_AGCRegisterHook,(YAP_agc_hook));
 
+/*  void  YAP_AtomReleaseHold(YAP_Atom)  */
+extern X_API int  PROTO(YAP_HaltRegisterHook,(YAP_halt_hook, void *));
+
 /*  char *YAP_cwd(void)  */
 extern X_API char *  PROTO(YAP_cwd,(void));
 

include/yap_structs.h

@@ -176,6 +176,8 @@ typedef struct {
 
 typedef int  (*YAP_agc_hook)(void *_Atom);
 
+typedef void  (*YAP_halt_hook)(int exit_code, void *closure);
+
 /********* execution mode ***********************/
 
 typedef enum

library/yap2swi/yap2swi.c

@@ -3249,6 +3249,7 @@ X_API void (*PL_signal(int sig, void (*func)(int)))(int)
 
 X_API void PL_on_halt(void (*f)(int, void *), void *closure)
 {
+  Yap_HaltRegisterHook((HaltHookFunc)f,closure);
 }
 
 void Yap_swi_install(void);

misc/HEAPFIELDS

@@ -295,6 +295,9 @@ struct operator_entry	*op_list	OpList			=NULL OpListAdjust
 /* stream array */
 struct stream_desc *yap_streams		Stream			=NULL RestoreStreams()
 
+/* halt hooks */
+struct halt_hook *yap_halt_hook		Yap_HaltHooks		=NULL RestoreHaltHooks()
+
 /* stream aliases */
 UInt		n_of_file_aliases	NOfFileAliases		=0 void
 UInt		sz_of_file_aliases	SzOfFileAliases		=0 void