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
  55 #include "libguile/validate.h"
  56 #include "libguile/async.h"
  57
  58 #ifdef HAVE_STRING_H
  59 #include <string.h>
  60 #endif
  61 #ifdef HAVE_UNISTD_H
  62 #include <unistd.h>
  63 #endif
  64
  65
  66 \f
  67 /* {Asynchronous Events}
  68  *
  69  *
  70  * Async == thunk + mark.
  71  *
  72  * Setting the mark guarantees future execution of the thunk.  More
  73  * than one set may be satisfied by a single execution.
  74  *
  75  * scm_tick_clock decremented once per SCM_ALLOW_INTS.
  76  * Async execution triggered by SCM_ALLOW_INTS when scm_tick_clock drops to 0.
  77  * Async execution prevented by scm_mask_ints != 0.
  78  *
  79  * If the clock reaches 0 when scm_mask_ints != 0, then reset the clock
  80  * to 1.
  81  *
  82  * If the clock reaches 0 any other time, run marked asyncs.
  83  *
  84  * From a unix signal handler, mark a corresponding async and set the clock
  85  * to 1.   Do SCM_REDEFER_INTS;/SCM_REALLOW_INTS so that if the signal handler is not
  86  * called in the dynamic scope of a critical section, it is excecuted immediately.
  87  *
  88  * Overall, closely timed signals of a particular sort may be combined.  Pending signals
  89  * are delivered in a fixed priority order, regardless of arrival order.
  90  *
  91  */
  92
  93 /* True between SCM_DEFER_INTS and SCM_ALLOW_INTS, and
  94  * when the interpreter is not running at all.
  95  */
  96 int scm_ints_disabled = 1;
  97 unsigned int scm_mask_ints = 1;
  98
  99 #ifdef GUILE_OLD_ASYNC_CLICK
 100 unsigned int scm_async_clock = 20;
 101 static unsigned int scm_async_rate = 20;
 102
 103 static unsigned int scm_tick_clock = 0;
 104 static unsigned int scm_tick_rate = 0;
 105 static unsigned int scm_desired_tick_rate = 0;
 106 static unsigned int scm_switch_clock = 0;
 107 static unsigned int scm_switch_rate = 0;
 108 static unsigned int scm_desired_switch_rate = 0;
 109 #else
 110 int scm_asyncs_pending_p = 0;
 111 #endif
 112
 113 static long tc16_async;
 114
 115 \f
 116
 117 /* cmm: this has SCM_ prefix because SCM_MAKE_VALIDATE expects it.
 118    this is ugly.  */
 119 #define SCM_ASYNCP(X) (SCM_NIMP(X) && (tc16_async == SCM_GCTYP16 (X)))
 120
 121 #define VALIDATE_ASYNC(pos,a) SCM_MAKE_VALIDATE(pos, a, ASYNCP)
 122
 123 #define ASYNC_GOT_IT(X)        (SCM_CELL_WORD_0 (X) >> 16)
 124 #define SET_ASYNC_GOT_IT(X, V) (SCM_SET_CELL_WORD_0 (X, (SCM_CELL_WORD_0 (X) & ((1 << 16) - 1)) | ((V) << 16)))
 125 #define ASYNC_THUNK(X)         SCM_CELL_OBJECT_1 (X)
 126
 127 \f
 128
 129 #ifdef GUILE_OLD_ASYNC_CLICK
 130 int
 131 scm_asyncs_pending ()
 132 {
 133   SCM pos;
 134   pos = scm_asyncs;
 135   while (pos != SCM_EOL)
 136     {
 137       SCM a = SCM_CAR (pos);
 138       if (ASYNC_GOT_IT (a))
 139         return 1;
 140       pos = SCM_CDR (pos);
 141     }
 142   return 0;
 143 }
 144
 145 #if 0
 146 static SCM
 147 scm_sys_tick_async_thunk (void)
 148 {
 149   scm_deliver_signal (SCM_TICK_SIGNAL);
 150   return SCM_BOOL_F;
 151 }
 152 #endif
 153
 154 void
 155 scm_async_click ()
 156 {
 157   int owe_switch;
 158   int owe_tick;
 159
 160   if (!scm_switch_rate)
 161     {
 162       owe_switch = 0;
 163       scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
 164       scm_desired_switch_rate = 0;
 165     }
 166   else
 167     {
 168       owe_switch = (scm_async_rate >= scm_switch_clock);
 169       if (owe_switch)
 170         {
 171           if (scm_desired_switch_rate)
 172             {
 173               scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
 174               scm_desired_switch_rate = 0;
 175             }
 176           else
 177             scm_switch_clock = scm_switch_rate;
 178         }
 179       else
 180         {
 181           if (scm_desired_switch_rate)
 182             {
 183               scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
 184               scm_desired_switch_rate = 0;
 185             }
 186           else
 187             scm_switch_clock -= scm_async_rate;
 188         }
 189     }
 190
 191   if (scm_mask_ints)
 192     {
 193       if (owe_switch)
 194         scm_switch ();
 195       scm_async_clock = 1;
 196       return;;
 197     }
 198
 199   if (!scm_tick_rate)
 200     {
 201       unsigned int r;
 202       owe_tick = 0;
 203       r = scm_desired_tick_rate;
 204       if (r)
 205         {
 206           scm_desired_tick_rate = 0;
 207           scm_tick_rate = r;
 208           scm_tick_clock = r;
 209         }
 210     }
 211   else
 212     {
 213       owe_tick = (scm_async_rate >= scm_tick_clock);
 214       if (owe_tick)
 215         {
 216           scm_tick_clock = scm_tick_rate = scm_desired_tick_rate;
 217           scm_desired_tick_rate = 0;
 218         }
 219       else
 220         {
 221           if (scm_desired_tick_rate)
 222             {
 223               scm_tick_clock = scm_tick_rate = scm_desired_tick_rate;
 224               scm_desired_tick_rate = 0;
 225             }
 226           else
 227             scm_tick_clock -= scm_async_rate;
 228         }
 229     }
 230
 231   /*
 232      if (owe_tick)
 233        scm_async_mark (system_signal_asyncs[SCM_SIG_ORD(SCM_TICK_SIGNAL)]); */
 234
 235   SCM_DEFER_INTS;
 236   if (scm_tick_rate && scm_switch_rate)
 237     {
 238       scm_async_rate = min (scm_tick_clock,  scm_switch_clock);
 239       scm_async_clock = scm_async_rate;
 240     }
 241   else if (scm_tick_rate)
 242     {
 243       scm_async_clock = scm_async_rate = scm_tick_clock;
 244     }
 245   else if (scm_switch_rate)
 246     {
 247       scm_async_clock = scm_async_rate = scm_switch_clock;
 248     }
 249   else
 250     scm_async_clock = scm_async_rate = 1 << 16;
 251   SCM_ALLOW_INTS_ONLY;
 252
 253  tail:
 254   scm_run_asyncs (scm_asyncs);
 255
 256   SCM_DEFER_INTS;
 257   if (scm_asyncs_pending ())
 258     {
 259       SCM_ALLOW_INTS_ONLY;
 260       goto tail;
 261     }
 262   SCM_ALLOW_INTS;
 263
 264   if (owe_switch)
 265     scm_switch ();
 266 }
 267
 268 void
 269 scm_switch ()
 270 {
 271 #if 0 /* Thread switching code should probably reside here, but the
 272          async switching code doesn't seem to work, so it's put in the
 273          SCM_DEFER_INTS macro instead. /mdj */
 274   SCM_THREAD_SWITCHING_CODE;
 275 #endif
 276 }
 277
 278 #else
 279
 280 void
 281 scm_async_click ()
 282 {
 283   if (!scm_mask_ints)
 284     do
 285       scm_run_asyncs (scm_asyncs);
 286     while (scm_asyncs_pending_p);
 287 }
 288
 289 #endif
 290
 291
 292 \f
 293
 294 static SCM
 295 mark_async (SCM obj)
 296 {
 297   return ASYNC_THUNK (obj);
 298 }
 299
 300 \f
 301
 302 SCM_DEFINE (scm_async, "async", 1, 0, 0,
 303            (SCM thunk),
 304 "")
 305 #define FUNC_NAME s_scm_async
 306 {
 307   SCM_RETURN_NEWSMOB (tc16_async, SCM_UNPACK (thunk));
 308 }
 309 #undef FUNC_NAME
 310
 311 SCM_DEFINE (scm_system_async, "system-async", 1, 0, 0,
 312             (SCM thunk),
 313 "")
 314 #define FUNC_NAME s_scm_system_async
 315 {
 316   SCM it;
 317   SCM list;
 318
 319   it = scm_async (thunk);
 320   SCM_NEWCELL (list);
 321   SCM_SETCAR (list, it);
 322   SCM_SETCDR (list, scm_asyncs);
 323   scm_asyncs = list;
 324   return it;
 325 }
 326 #undef FUNC_NAME
 327
 328 SCM_DEFINE (scm_async_mark, "async-mark", 1, 0, 0,
 329             (SCM a),
 330 "")
 331 #define FUNC_NAME s_scm_async_mark
 332 {
 333   VALIDATE_ASYNC (1, a);
 334 #ifdef GUILE_OLD_ASYNC_CLICK
 335   SET_ASYNC_GOT_IT (a, 1);
 336 #else
 337   SET_ASYNC_GOT_IT (a, scm_asyncs_pending_p = 1);
 338 #endif
 339   return SCM_UNSPECIFIED;
 340 }
 341 #undef FUNC_NAME
 342
 343
 344 SCM_DEFINE (scm_system_async_mark, "system-async-mark", 1, 0, 0,
 345            (SCM a),
 346 "")
 347 #define FUNC_NAME s_scm_system_async_mark
 348 {
 349   VALIDATE_ASYNC (1, a);
 350   SCM_REDEFER_INTS;
 351 #ifdef GUILE_OLD_ASYNC_CLICK
 352   SET_ASYNC_GOT_IT (a, 1);
 353   scm_async_rate = 1 + scm_async_rate - scm_async_clock;
 354   scm_async_clock = 1;
 355 #else
 356   SET_ASYNC_GOT_IT (a, scm_asyncs_pending_p = 1);
 357 #endif
 358   SCM_REALLOW_INTS;
 359   return SCM_UNSPECIFIED;
 360 }
 361 #undef FUNC_NAME
 362
 363
 364 SCM_DEFINE (scm_run_asyncs, "run-asyncs", 1, 0, 0,
 365            (SCM list_of_a),
 366 "")
 367 #define FUNC_NAME s_scm_run_asyncs
 368 {
 369 #ifdef GUILE_OLD_ASYNC_CLICK
 370   if (scm_mask_ints)
 371     return SCM_BOOL_F;
 372 #else
 373   scm_asyncs_pending_p = 0;
 374 #endif
 375   while (! SCM_NULLP (list_of_a))
 376     {
 377       SCM a;
 378       SCM_VALIDATE_CONS (1, list_of_a);
 379       a = SCM_CAR (list_of_a);
 380       VALIDATE_ASYNC (SCM_ARG1, a);
 381       scm_mask_ints = 1;
 382       if (ASYNC_GOT_IT (a))
 383         {
 384           SET_ASYNC_GOT_IT (a, 0);
 385           scm_apply (ASYNC_THUNK (a), SCM_EOL, SCM_EOL);
 386         }
 387       scm_mask_ints = 0;
 388       list_of_a = SCM_CDR (list_of_a);
 389     }
 390   return SCM_BOOL_T;
 391 }
 392 #undef FUNC_NAME
 393
 394 \f
 395
 396
 397 SCM_DEFINE (scm_noop, "noop", 0, 0, 1,
 398            (SCM args),
 399 "")
 400 #define FUNC_NAME s_scm_noop
 401 {
 402   return (SCM_NULLP (args) ? SCM_BOOL_F : SCM_CAR (args));
 403 }
 404 #undef FUNC_NAME
 405
 406
 407 \f
 408
 409 #ifdef GUILE_OLD_ASYNC_CLICK
 410
 411 SCM_DEFINE (scm_set_tick_rate, "set-tick-rate", 1, 0, 0,
 412            (SCM n),
 413 "")
 414 #define FUNC_NAME s_scm_set_tick_rate
 415 {
 416   unsigned int old_n = scm_tick_rate;
 417   SCM_VALIDATE_INUM (1, n);
 418   scm_desired_tick_rate = SCM_INUM (n);
 419   scm_async_rate = 1 + scm_async_rate - scm_async_clock;
 420   scm_async_clock = 1;
 421   return SCM_MAKINUM (old_n);
 422 }
 423 #undef FUNC_NAME
 424
 425 \f
 426
 427
 428 SCM_DEFINE (scm_set_switch_rate, "set-switch-rate", 1, 0, 0,
 429            (SCM n),
 430 "")
 431 #define FUNC_NAME s_scm_set_switch_rate
 432 {
 433   unsigned int old_n = scm_switch_rate;
 434   SCM_VALIDATE_INUM (1, n);
 435   scm_desired_switch_rate = SCM_INUM (n);
 436   scm_async_rate = 1 + scm_async_rate - scm_async_clock;
 437   scm_async_clock = 1;
 438   return SCM_MAKINUM (old_n);
 439 }
 440 #undef FUNC_NAME
 441
 442 #endif
 443 \f
 444
 445 /* points to the GC system-async, so that scm_gc_end can find it.  */
 446 SCM scm_gc_async;
 447
 448 /* the vcell for gc-thunk.  */
 449 static SCM scm_gc_vcell;
 450
 451 /* the thunk installed in the GC system-async, which is marked at the
 452    end of garbage collection.  */
 453 static SCM
 454 scm_sys_gc_async_thunk (void)
 455 {
 456   if (SCM_NFALSEP (scm_gc_vcell))
 457     {
 458       SCM proc = SCM_CDR (scm_gc_vcell);
 459
 460       if (SCM_NFALSEP (proc) && !SCM_UNBNDP (proc))
 461         scm_apply (proc, SCM_EOL, SCM_EOL);
 462     }
 463   return SCM_UNSPECIFIED;
 464 }
 465
 466 \f
 467
 468 SCM_DEFINE (scm_unmask_signals, "unmask-signals", 0, 0, 0,
 469            (),
 470 "")
 471 #define FUNC_NAME s_scm_unmask_signals
 472 {
 473   scm_mask_ints = 0;
 474   return SCM_UNSPECIFIED;
 475 }
 476 #undef FUNC_NAME
 477
 478
 479 SCM_DEFINE (scm_mask_signals, "mask-signals", 0, 0, 0,
 480            (),
 481 "")
 482 #define FUNC_NAME s_scm_mask_signals
 483 {
 484   scm_mask_ints = 1;
 485   return SCM_UNSPECIFIED;
 486 }
 487 #undef FUNC_NAME
 488
 489 \f
 490
 491 void
 492 scm_init_async ()
 493 {
 494   SCM a_thunk;
 495   tc16_async = scm_make_smob_type_mfpe ("async", 0,
 496                                            mark_async, NULL, NULL, NULL);
 497   scm_gc_vcell = scm_sysintern ("gc-thunk", SCM_BOOL_F);
 498   a_thunk = scm_make_gsubr ("%gc-thunk", 0, 0, 0, scm_sys_gc_async_thunk);
 499   scm_gc_async = scm_system_async (a_thunk);
 500
 501 #include "libguile/async.x"
 502 }
 503
 504 /*
 505   Local Variables:
 506   c-file-style: "gnu"
 507   End:
 508 */