libguile/async.c

   1 /* Copyright (C) 1995,1996,1997,1998,2000,2001, 2002 Free Software Foundation, Inc.
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
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   6  * any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this software; see the file COPYING.  If not, write to
  15  * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  16  * Boston, MA 02111-1307 USA
  17  *
  18  * As a special exception, the Free Software Foundation gives permission
  19  * for additional uses of the text contained in its release of GUILE.
  20  *
  21  * The exception is that, if you link the GUILE library with other files
  22  * to produce an executable, this does not by itself cause the
  23  * resulting executable to be covered by the GNU General Public License.
  24  * Your use of that executable is in no way restricted on account of
  25  * linking the GUILE library code into it.
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  30  * This exception applies only to the code released by the
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  40  * If you do not wish that, delete this exception notice.  */
  41
  42
  43 \f
  44
  45 #include <signal.h>
  46 #include "libguile/_scm.h"
  47 #include "libguile/eval.h"
  48 #include "libguile/throw.h"
  49 #include "libguile/root.h"
  50 #include "libguile/smob.h"
  51 #include "libguile/lang.h"
  52 #include "libguile/deprecation.h"
  53
  54 #include "libguile/validate.h"
  55 #include "libguile/async.h"
  56
  57 #ifdef HAVE_STRING_H
  58 #include <string.h>
  59 #endif
  60 #ifdef HAVE_UNISTD_H
  61 #include <unistd.h>
  62 #endif
  63
  64
  65 \f
  66 /* {Asynchronous Events}
  67  *
  68  * There are two kinds of asyncs: system asyncs and user asyncs.  The
  69  * two kinds have some concepts in commen but work slightly
  70  * differently and are not interchangeable.
  71  *
  72  * System asyncs are used to run arbitrary code at the next safe point
  73  * in a specified thread.  You can use them to trigger execution of
  74  * Scheme code from signal handlers or to interrupt a thread, for
  75  * example.
  76  *
  77  * Each thread has a list of 'activated asyncs', which is a normal
  78  * Scheme list of procedures with zero arguments.  When a thread
  79  * executes a SCM_ASYNC_TICK statement (which is included in
  80  * SCM_TICK), it will call all procedures on this list.
  81  *
  82  * Also, a thread will wake up when a procedure is added to its list
  83  * of active asyncs and call them.  After that, it will go to sleep
  84  * again.  (Not implemented yet.)
  85  *
  86  *
  87  * User asyncs are a little data structure that consists of a
  88  * procedure of zero arguments and a mark.  There are functions for
  89  * setting the mark of a user async and for calling all procedures of
  90  * marked asyncs in a given list.  Nothing you couldn't quickly
  91  * implement yourself.
  92  */
  93
  94 /* True between SCM_DEFER_INTS and SCM_ALLOW_INTS, and
  95  * when the interpreter is not running at all.
  96  */
  97 int scm_ints_disabled = 1;
  98 unsigned int scm_mask_ints = 1;
  99
 100 \f
 101
 102 /* User asyncs. */
 103
 104 static scm_t_bits tc16_async;
 105
 106 /* cmm: this has SCM_ prefix because SCM_MAKE_VALIDATE expects it.
 107    this is ugly.  */
 108 #define SCM_ASYNCP(X)           SCM_TYP16_PREDICATE (tc16_async, X)
 109 #define VALIDATE_ASYNC(pos, a)  SCM_MAKE_VALIDATE(pos, a, ASYNCP)
 110
 111 #define ASYNC_GOT_IT(X)        (SCM_CELL_WORD_0 (X) >> 16)
 112 #define SET_ASYNC_GOT_IT(X, V) (SCM_SET_CELL_WORD_0 ((X), SCM_TYP16 (X) | ((V) << 16)))
 113 #define ASYNC_THUNK(X)         SCM_CELL_OBJECT_1 (X)
 114
 115 static SCM
 116 async_gc_mark (SCM obj)
 117 {
 118   return ASYNC_THUNK (obj);
 119 }
 120
 121 SCM_DEFINE (scm_async, "async", 1, 0, 0,
 122             (SCM thunk),
 123             "Create a new async for the procedure @var{thunk}.")
 124 #define FUNC_NAME s_scm_async
 125 {
 126   SCM_RETURN_NEWSMOB (tc16_async, SCM_UNPACK (thunk));
 127 }
 128 #undef FUNC_NAME
 129
 130 SCM_DEFINE (scm_async_mark, "async-mark", 1, 0, 0,
 131             (SCM a),
 132             "Mark the async @var{a} for future execution.")
 133 #define FUNC_NAME s_scm_async_mark
 134 {
 135   VALIDATE_ASYNC (1, a);
 136   SET_ASYNC_GOT_IT (a, 1);
 137   return SCM_UNSPECIFIED;
 138 }
 139 #undef FUNC_NAME
 140
 141 SCM_DEFINE (scm_run_asyncs, "run-asyncs", 1, 0, 0,
 142             (SCM list_of_a),
 143             "Execute all thunks from the asyncs of the list @var{list_of_a}.")
 144 #define FUNC_NAME s_scm_run_asyncs
 145 {
 146   while (! SCM_NULL_OR_NIL_P (list_of_a))
 147     {
 148       SCM a;
 149       SCM_VALIDATE_CONS (1, list_of_a);
 150       a = SCM_CAR (list_of_a);
 151       VALIDATE_ASYNC (SCM_ARG1, a);
 152       scm_mask_ints = 1;
 153       if (ASYNC_GOT_IT (a))
 154         {
 155           SET_ASYNC_GOT_IT (a, 0);
 156           scm_call_0 (ASYNC_THUNK (a));
 157         }
 158       scm_mask_ints = 0;
 159       list_of_a = SCM_CDR (list_of_a);
 160     }
 161   return SCM_BOOL_T;
 162 }
 163 #undef FUNC_NAME
 164
 165 \f
 166
 167 /* System asyncs. */
 168
 169 void
 170 scm_async_click ()
 171 {
 172   SCM asyncs;
 173
 174   if (!scm_mask_ints)
 175     {
 176       while (!SCM_NULLP(asyncs = scm_active_asyncs))
 177         {
 178           scm_active_asyncs = SCM_EOL;
 179           do
 180             {
 181               SCM c = SCM_CDR (asyncs);
 182               SCM_SETCDR (asyncs, SCM_EOL);
 183               scm_call_0 (SCM_CAR (asyncs));
 184               asyncs = c;
 185             }
 186           while (!SCM_NULLP(asyncs));
 187         }
 188     }
 189 }
 190
 191 SCM_DEFINE (scm_system_async, "system-async", 1, 0, 0,
 192             (SCM thunk),
 193             "This function is deprecated.  You can use @var{thunk} directly\n"
 194             "instead of explicitely creating a asnc object.\n")
 195 #define FUNC_NAME s_scm_system_async
 196 {
 197   scm_c_issue_deprecation_warning
 198     ("'system-async' is deprecated.  "
 199      "Use the procedure directly with 'system-async-mark'.");
 200   return thunk;
 201 }
 202 #undef FUNC_NAME
 203
 204 void
 205 scm_i_queue_async_cell (SCM c, scm_root_state *root)
 206 {
 207   if (SCM_CDR (c) == SCM_EOL)
 208     {
 209       SCM_SETCDR (c, root->active_asyncs);
 210       root->active_asyncs = c;
 211     }
 212 }
 213
 214 SCM_DEFINE (scm_system_async_mark_for_thread, "system-async-mark", 1, 1, 0,
 215            (SCM proc, SCM thread),
 216             "Register the procedure @var{proc} for future execution\n"
 217             "in @var{thread}.  When @var{thread} is not specified,\n"
 218             "use the current thread.")
 219 #define FUNC_NAME s_scm_system_async_mark_for_thread
 220 {
 221   scm_i_queue_async_cell (scm_cons (proc, SCM_EOL),
 222                           (SCM_UNBNDP (thread)
 223                            ? scm_root
 224                            : scm_i_thread_root (thread)));
 225   return SCM_UNSPECIFIED;
 226 }
 227 #undef FUNC_NAME
 228
 229 SCM
 230 scm_system_async_mark (SCM proc)
 231 #define FUNC_NAME s_scm_system_async_mark_for_thread
 232 {
 233   return scm_system_async_mark_for_thread (proc, SCM_UNDEFINED);
 234 }
 235 #undef FUNC_NAME
 236
 237 \f
 238
 239
 240 SCM_DEFINE (scm_noop, "noop", 0, 0, 1,
 241             (SCM args),
 242             "Do nothing.  When called without arguments, return @code{#f},\n"
 243             "otherwise return the first argument.")
 244 #define FUNC_NAME s_scm_noop
 245 {
 246   SCM_VALIDATE_REST_ARGUMENT (args);
 247   return (SCM_NULL_OR_NIL_P (args) ? SCM_BOOL_F : SCM_CAR (args));
 248 }
 249 #undef FUNC_NAME
 250
 251
 252 \f
 253
 254 SCM_DEFINE (scm_unmask_signals, "unmask-signals", 0, 0, 0,
 255             (),
 256             "Unmask signals. The returned value is not specified.")
 257 #define FUNC_NAME s_scm_unmask_signals
 258 {
 259   scm_mask_ints = 0;
 260   return SCM_UNSPECIFIED;
 261 }
 262 #undef FUNC_NAME
 263
 264
 265 SCM_DEFINE (scm_mask_signals, "mask-signals", 0, 0, 0,
 266             (),
 267             "Mask signals. The returned value is not specified.")
 268 #define FUNC_NAME s_scm_mask_signals
 269 {
 270   scm_mask_ints = 1;
 271   return SCM_UNSPECIFIED;
 272 }
 273 #undef FUNC_NAME
 274
 275 \f
 276
 277 void
 278 scm_init_async ()
 279 {
 280   scm_asyncs = SCM_EOL;
 281   tc16_async = scm_make_smob_type ("async", 0);
 282   scm_set_smob_mark (tc16_async, async_gc_mark);
 283
 284 #include "libguile/async.x"
 285 }
 286
 287 /*
 288   Local Variables:
 289   c-file-style: "gnu"
 290   End:
 291 */