libguile/async.c

   1 /* Copyright (C) 1995, 96, 97, 98, 2000 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
   5  * the Free Software Foundation; either version 2, or (at your option)
   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.
  26  *
  27  * This exception does not however invalidate any other reasons why
  28  * the executable file might be covered by the GNU General Public License.
  29  *
  30  * This exception applies only to the code released by the
  31  * Free Software Foundation under the name GUILE.  If you copy
  32  * code from other Free Software Foundation releases into a copy of
  33  * GUILE, as the General Public License permits, the exception does
  34  * not apply to the code that you add in this way.  To avoid misleading
  35  * anyone as to the status of such modified files, you must delete
  36  * this exception notice from them.
  37  *
  38  * If you write modifications of your own for GUILE, it is your choice
  39  * whether to permit this exception to apply to your modifications.
  40  * If you do not wish that, delete this exception notice.  */
  41
  42 /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
  43    gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
  44
  45 \f
  46
  47 #include <stdio.h>
  48 #include <signal.h>
  49 #include "libguile/_scm.h"
  50 #include "libguile/eval.h"
  51 #include "libguile/throw.h"
  52 #include "libguile/root.h"
  53 #include "libguile/smob.h"
  54 #include "libguile/gc.h"
  55
  56 #include "libguile/validate.h"
  57 #include "libguile/async.h"
  58
  59 #ifdef HAVE_STRING_H
  60 #include <string.h>
  61 #endif
  62 #ifdef HAVE_UNISTD_H
  63 #include <unistd.h>
  64 #endif
  65
  66
  67 \f
  68 /* {Asynchronous Events}
  69  *
  70  *
  71  * Async == thunk + mark.
  72  *
  73  * Setting the mark guarantees future execution of the thunk.  More
  74  * than one set may be satisfied by a single execution.
  75  *
  76  * scm_tick_clock decremented once per SCM_ALLOW_INTS.
  77  * Async execution triggered by SCM_ALLOW_INTS when scm_tick_clock drops to 0.
  78  * Async execution prevented by scm_mask_ints != 0.
  79  *
  80  * If the clock reaches 0 when scm_mask_ints != 0, then reset the clock
  81  * to 1.
  82  *
  83  * If the clock reaches 0 any other time, run marked asyncs.
  84  *
  85  * From a unix signal handler, mark a corresponding async and set the clock
  86  * to 1.   Do SCM_REDEFER_INTS;/SCM_REALLOW_INTS so that if the signal handler is not
  87  * called in the dynamic scope of a critical section, it is excecuted immediately.
  88  *
  89  * Overall, closely timed signals of a particular sort may be combined.  Pending signals
  90  * are delivered in a fixed priority order, regardless of arrival order.
  91  *
  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 #ifdef GUILE_OLD_ASYNC_CLICK
 101 unsigned int scm_async_clock = 20;
 102 static unsigned int scm_async_rate = 20;
 103
 104 static unsigned int scm_tick_clock = 0;
 105 static unsigned int scm_tick_rate = 0;
 106 static unsigned int scm_desired_tick_rate = 0;
 107 static unsigned int scm_switch_clock = 0;
 108 static unsigned int scm_switch_rate = 0;
 109 static unsigned int scm_desired_switch_rate = 0;
 110 #else
 111 int scm_asyncs_pending_p = 0;
 112 #endif
 113
 114 static long tc16_async;
 115
 116 \f
 117
 118 /* cmm: this has SCM_ prefix because SCM_MAKE_VALIDATE expects it.
 119    this is ugly.  */
 120 #define SCM_ASYNCP(X) (SCM_NIMP(X) && (tc16_async == SCM_GCTYP16 (X)))
 121
 122 #define VALIDATE_ASYNC(pos,a) SCM_MAKE_VALIDATE(pos, a, ASYNCP)
 123
 124 #define ASYNC_GOT_IT(X)        (SCM_CELL_WORD_0 (X) >> 16)
 125 #define SET_ASYNC_GOT_IT(X, V) (SCM_SET_CELL_WORD_0 (X, (SCM_CELL_WORD_0 (X) & ((1 << 16) - 1)) | ((V) << 16)))
 126 #define ASYNC_THUNK(X)         SCM_CELL_OBJECT_1 (X)
 127
 128 \f
 129
 130 #ifdef GUILE_OLD_ASYNC_CLICK
 131 int
 132 scm_asyncs_pending ()
 133 {
 134   SCM pos;
 135   pos = scm_asyncs;
 136   while (pos != SCM_EOL)
 137     {
 138       SCM a = SCM_CAR (pos);
 139       if (ASYNC_GOT_IT (a))
 140         return 1;
 141       pos = SCM_CDR (pos);
 142     }
 143   return 0;
 144 }
 145
 146 #if 0
 147 static SCM
 148 scm_sys_tick_async_thunk (void)
 149 {
 150   scm_deliver_signal (SCM_TICK_SIGNAL);
 151   return SCM_BOOL_F;
 152 }
 153 #endif
 154
 155 void
 156 scm_async_click ()
 157 {
 158   int owe_switch;
 159   int owe_tick;
 160
 161   if (!scm_switch_rate)
 162     {
 163       owe_switch = 0;
 164       scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
 165       scm_desired_switch_rate = 0;
 166     }
 167   else
 168     {
 169       owe_switch = (scm_async_rate >= scm_switch_clock);
 170       if (owe_switch)
 171         {
 172           if (scm_desired_switch_rate)
 173             {
 174               scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
 175               scm_desired_switch_rate = 0;
 176             }
 177           else
 178             scm_switch_clock = scm_switch_rate;
 179         }
 180       else
 181         {
 182           if (scm_desired_switch_rate)
 183             {
 184               scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
 185               scm_desired_switch_rate = 0;
 186             }
 187           else
 188             scm_switch_clock -= scm_async_rate;
 189         }
 190     }
 191
 192   if (scm_mask_ints)
 193     {
 194       if (owe_switch)
 195         scm_switch ();
 196       scm_async_clock = 1;
 197       return;;
 198     }
 199
 200   if (!scm_tick_rate)
 201     {
 202       unsigned int r;
 203       owe_tick = 0;
 204       r = scm_desired_tick_rate;
 205       if (r)
 206         {
 207           scm_desired_tick_rate = 0;
 208           scm_tick_rate = r;
 209           scm_tick_clock = r;
 210         }
 211     }
 212   else
 213     {
 214       owe_tick = (scm_async_rate >= scm_tick_clock);
 215       if (owe_tick)
 216         {
 217           scm_tick_clock = scm_tick_rate = scm_desired_tick_rate;
 218           scm_desired_tick_rate = 0;
 219         }
 220       else
 221         {
 222           if (scm_desired_tick_rate)
 223             {
 224               scm_tick_clock = scm_tick_rate = scm_desired_tick_rate;
 225               scm_desired_tick_rate = 0;
 226             }
 227           else
 228             scm_tick_clock -= scm_async_rate;
 229         }
 230     }
 231
 232   /*
 233      if (owe_tick)
 234        scm_async_mark (system_signal_asyncs[SCM_SIG_ORD(SCM_TICK_SIGNAL)]); */
 235
 236   SCM_DEFER_INTS;
 237   if (scm_tick_rate && scm_switch_rate)
 238     {
 239       scm_async_rate = min (scm_tick_clock,  scm_switch_clock);
 240       scm_async_clock = scm_async_rate;
 241     }
 242   else if (scm_tick_rate)
 243     {
 244       scm_async_clock = scm_async_rate = scm_tick_clock;
 245     }
 246   else if (scm_switch_rate)
 247     {
 248       scm_async_clock = scm_async_rate = scm_switch_clock;
 249     }
 250   else
 251     scm_async_clock = scm_async_rate = 1 << 16;
 252   SCM_ALLOW_INTS_ONLY;
 253
 254  tail:
 255   scm_run_asyncs (scm_asyncs);
 256
 257   SCM_DEFER_INTS;
 258   if (scm_asyncs_pending ())
 259     {
 260       SCM_ALLOW_INTS_ONLY;
 261       goto tail;
 262     }
 263   SCM_ALLOW_INTS;
 264
 265   if (owe_switch)
 266     scm_switch ();
 267 }
 268
 269 void
 270 scm_switch ()
 271 {
 272 #if 0 /* Thread switching code should probably reside here, but the
 273          async switching code doesn't seem to work, so it's put in the
 274          SCM_DEFER_INTS macro instead. /mdj */
 275   SCM_THREAD_SWITCHING_CODE;
 276 #endif
 277 }
 278
 279 #else
 280
 281 void
 282 scm_async_click ()
 283 {
 284   if (!scm_mask_ints)
 285     do
 286       scm_run_asyncs (scm_asyncs);
 287     while (scm_asyncs_pending_p);
 288 }
 289
 290 #endif
 291
 292
 293 \f
 294
 295 static SCM
 296 mark_async (SCM obj)
 297 {
 298   return ASYNC_THUNK (obj);
 299 }
 300
 301 \f
 302
 303 SCM_DEFINE (scm_async, "async", 1, 0, 0,
 304            (SCM thunk),
 305 "")
 306 #define FUNC_NAME s_scm_async
 307 {
 308   SCM_RETURN_NEWSMOB (tc16_async, SCM_UNPACK (thunk));
 309 }
 310 #undef FUNC_NAME
 311
 312 SCM_DEFINE (scm_system_async, "system-async", 1, 0, 0,
 313             (SCM thunk),
 314 "")
 315 #define FUNC_NAME s_scm_system_async
 316 {
 317   SCM it;
 318   SCM list;
 319
 320   it = scm_async (thunk);
 321   SCM_NEWCELL (list);
 322   SCM_SETCAR (list, it);
 323   SCM_SETCDR (list, scm_asyncs);
 324   scm_asyncs = list;
 325   return it;
 326 }
 327 #undef FUNC_NAME
 328
 329 SCM_DEFINE (scm_async_mark, "async-mark", 1, 0, 0,
 330             (SCM a),
 331 "")
 332 #define FUNC_NAME s_scm_async_mark
 333 {
 334   VALIDATE_ASYNC (1, a);
 335 #ifdef GUILE_OLD_ASYNC_CLICK
 336   SET_ASYNC_GOT_IT (a, 1);
 337 #else
 338   SET_ASYNC_GOT_IT (a, scm_asyncs_pending_p = 1);
 339 #endif
 340   return SCM_UNSPECIFIED;
 341 }
 342 #undef FUNC_NAME
 343
 344
 345 SCM_DEFINE (scm_system_async_mark, "system-async-mark", 1, 0, 0,
 346            (SCM a),
 347 "")
 348 #define FUNC_NAME s_scm_system_async_mark
 349 {
 350   VALIDATE_ASYNC (1, a);
 351   SCM_REDEFER_INTS;
 352 #ifdef GUILE_OLD_ASYNC_CLICK
 353   SET_ASYNC_GOT_IT (a, 1);
 354   scm_async_rate = 1 + scm_async_rate - scm_async_clock;
 355   scm_async_clock = 1;
 356 #else
 357   SET_ASYNC_GOT_IT (a, scm_asyncs_pending_p = 1);
 358 #endif
 359   SCM_REALLOW_INTS;
 360   return SCM_UNSPECIFIED;
 361 }
 362 #undef FUNC_NAME
 363
 364
 365 SCM_DEFINE (scm_run_asyncs, "run-asyncs", 1, 0, 0,
 366            (SCM list_of_a),
 367 "")
 368 #define FUNC_NAME s_scm_run_asyncs
 369 {
 370 #ifdef GUILE_OLD_ASYNC_CLICK
 371   if (scm_mask_ints)
 372     return SCM_BOOL_F;
 373 #else
 374   scm_asyncs_pending_p = 0;
 375 #endif
 376   while (! SCM_NULLP (list_of_a))
 377     {
 378       SCM a;
 379       SCM_VALIDATE_CONS (1, list_of_a);
 380       a = SCM_CAR (list_of_a);
 381       VALIDATE_ASYNC (SCM_ARG1, a);
 382       scm_mask_ints = 1;
 383       if (ASYNC_GOT_IT (a))
 384         {
 385           SET_ASYNC_GOT_IT (a, 0);
 386           scm_apply (ASYNC_THUNK (a), SCM_EOL, SCM_EOL);
 387         }
 388       scm_mask_ints = 0;
 389       list_of_a = SCM_CDR (list_of_a);
 390     }
 391   return SCM_BOOL_T;
 392 }
 393 #undef FUNC_NAME
 394
 395 \f
 396
 397
 398 SCM_DEFINE (scm_noop, "noop", 0, 0, 1,
 399            (SCM args),
 400 "")
 401 #define FUNC_NAME s_scm_noop
 402 {
 403   return (SCM_NULLP (args) ? SCM_BOOL_F : SCM_CAR (args));
 404 }
 405 #undef FUNC_NAME
 406
 407
 408 \f
 409
 410 #ifdef GUILE_OLD_ASYNC_CLICK
 411
 412 SCM_DEFINE (scm_set_tick_rate, "set-tick-rate", 1, 0, 0,
 413            (SCM n),
 414 "")
 415 #define FUNC_NAME s_scm_set_tick_rate
 416 {
 417   unsigned int old_n = scm_tick_rate;
 418   SCM_VALIDATE_INUM (1, n);
 419   scm_desired_tick_rate = SCM_INUM (n);
 420   scm_async_rate = 1 + scm_async_rate - scm_async_clock;
 421   scm_async_clock = 1;
 422   return SCM_MAKINUM (old_n);
 423 }
 424 #undef FUNC_NAME
 425
 426 \f
 427
 428
 429 SCM_DEFINE (scm_set_switch_rate, "set-switch-rate", 1, 0, 0,
 430            (SCM n),
 431 "")
 432 #define FUNC_NAME s_scm_set_switch_rate
 433 {
 434   unsigned int old_n = scm_switch_rate;
 435   SCM_VALIDATE_INUM (1, n);
 436   scm_desired_switch_rate = SCM_INUM (n);
 437   scm_async_rate = 1 + scm_async_rate - scm_async_clock;
 438   scm_async_clock = 1;
 439   return SCM_MAKINUM (old_n);
 440 }
 441 #undef FUNC_NAME
 442
 443 #endif
 444 \f
 445
 446 /* points to the GC system-async, so that scm_gc_end can find it.  */
 447 SCM scm_gc_async;
 448
 449 /* the vcell for gc-thunk.  */
 450 static SCM scm_gc_vcell;
 451
 452 /* the thunk installed in the GC system-async, which is marked at the
 453    end of garbage collection.  */
 454 static SCM
 455 scm_sys_gc_async_thunk (void)
 456 {
 457   scm_c_run_hook (scm_after_gc_hook, SCM_EOL);
 458
 459 #if (SCM_DEBUG_DEPRECATED == 0)
 460
 461   /* The following code will be removed in Guile 1.5.  */
 462   if (SCM_NFALSEP (scm_gc_vcell))
 463     {
 464       SCM proc = SCM_CDR (scm_gc_vcell);
 465
 466       if (SCM_NFALSEP (proc) && !SCM_UNBNDP (proc))
 467         scm_apply (proc, SCM_EOL, SCM_EOL);
 468     }
 469
 470 #endif  /* SCM_DEBUG_DEPRECATED == 0 */
 471
 472   return SCM_UNSPECIFIED;
 473 }
 474
 475 \f
 476
 477 SCM_DEFINE (scm_unmask_signals, "unmask-signals", 0, 0, 0,
 478            (),
 479 "")
 480 #define FUNC_NAME s_scm_unmask_signals
 481 {
 482   scm_mask_ints = 0;
 483   return SCM_UNSPECIFIED;
 484 }
 485 #undef FUNC_NAME
 486
 487
 488 SCM_DEFINE (scm_mask_signals, "mask-signals", 0, 0, 0,
 489            (),
 490 "")
 491 #define FUNC_NAME s_scm_mask_signals
 492 {
 493   scm_mask_ints = 1;
 494   return SCM_UNSPECIFIED;
 495 }
 496 #undef FUNC_NAME
 497
 498 \f
 499
 500 void
 501 scm_init_async ()
 502 {
 503   SCM a_thunk;
 504   tc16_async = scm_make_smob_type_mfpe ("async", 0,
 505                                            mark_async, NULL, NULL, NULL);
 506   scm_gc_vcell = scm_sysintern ("gc-thunk", SCM_BOOL_F);
 507   a_thunk = scm_make_gsubr ("%gc-thunk", 0, 0, 0, scm_sys_gc_async_thunk);
 508   scm_gc_async = scm_system_async (a_thunk);
 509
 510 #include "libguile/async.x"
 511 }
 512
 513 /*
 514   Local Variables:
 515   c-file-style: "gnu"
 516   End:
 517 */