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_TYP16 (X) | ((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
 146 void
 147 scm_async_click ()
 148 {
 149   int owe_switch;
 150   int owe_tick;
 151
 152   if (!scm_switch_rate)
 153     {
 154       owe_switch = 0;
 155       scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
 156       scm_desired_switch_rate = 0;
 157     }
 158   else
 159     {
 160       owe_switch = (scm_async_rate >= scm_switch_clock);
 161       if (owe_switch)
 162         {
 163           if (scm_desired_switch_rate)
 164             {
 165               scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
 166               scm_desired_switch_rate = 0;
 167             }
 168           else
 169             scm_switch_clock = scm_switch_rate;
 170         }
 171       else
 172         {
 173           if (scm_desired_switch_rate)
 174             {
 175               scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
 176               scm_desired_switch_rate = 0;
 177             }
 178           else
 179             scm_switch_clock -= scm_async_rate;
 180         }
 181     }
 182
 183   if (scm_mask_ints)
 184     {
 185       if (owe_switch)
 186         scm_switch ();
 187       scm_async_clock = 1;
 188       return;;
 189     }
 190
 191   if (!scm_tick_rate)
 192     {
 193       unsigned int r;
 194       owe_tick = 0;
 195       r = scm_desired_tick_rate;
 196       if (r)
 197         {
 198           scm_desired_tick_rate = 0;
 199           scm_tick_rate = r;
 200           scm_tick_clock = r;
 201         }
 202     }
 203   else
 204     {
 205       owe_tick = (scm_async_rate >= scm_tick_clock);
 206       if (owe_tick)
 207         {
 208           scm_tick_clock = scm_tick_rate = scm_desired_tick_rate;
 209           scm_desired_tick_rate = 0;
 210         }
 211       else
 212         {
 213           if (scm_desired_tick_rate)
 214             {
 215               scm_tick_clock = scm_tick_rate = scm_desired_tick_rate;
 216               scm_desired_tick_rate = 0;
 217             }
 218           else
 219             scm_tick_clock -= scm_async_rate;
 220         }
 221     }
 222
 223   SCM_DEFER_INTS;
 224   if (scm_tick_rate && scm_switch_rate)
 225     {
 226       scm_async_rate = min (scm_tick_clock,  scm_switch_clock);
 227       scm_async_clock = scm_async_rate;
 228     }
 229   else if (scm_tick_rate)
 230     {
 231       scm_async_clock = scm_async_rate = scm_tick_clock;
 232     }
 233   else if (scm_switch_rate)
 234     {
 235       scm_async_clock = scm_async_rate = scm_switch_clock;
 236     }
 237   else
 238     scm_async_clock = scm_async_rate = 1 << 16;
 239   SCM_ALLOW_INTS_ONLY;
 240
 241  tail:
 242   scm_run_asyncs (scm_asyncs);
 243
 244   SCM_DEFER_INTS;
 245   if (scm_asyncs_pending ())
 246     {
 247       SCM_ALLOW_INTS_ONLY;
 248       goto tail;
 249     }
 250   SCM_ALLOW_INTS;
 251
 252   if (owe_switch)
 253     scm_switch ();
 254 }
 255
 256 void
 257 scm_switch ()
 258 {
 259 #if 0 /* Thread switching code should probably reside here, but the
 260          async switching code doesn't seem to work, so it's put in the
 261          SCM_DEFER_INTS macro instead. /mdj */
 262   SCM_THREAD_SWITCHING_CODE;
 263 #endif
 264 }
 265
 266 #else
 267
 268 void
 269 scm_async_click ()
 270 {
 271   if (!scm_mask_ints)
 272     do
 273       scm_run_asyncs (scm_asyncs);
 274     while (scm_asyncs_pending_p);
 275 }
 276
 277 #endif
 278
 279
 280 \f
 281
 282 static SCM
 283 mark_async (SCM obj)
 284 {
 285   return ASYNC_THUNK (obj);
 286 }
 287
 288 \f
 289
 290 SCM_DEFINE (scm_async, "async", 1, 0, 0,
 291            (SCM thunk),
 292 "")
 293 #define FUNC_NAME s_scm_async
 294 {
 295   SCM_RETURN_NEWSMOB (tc16_async, SCM_UNPACK (thunk));
 296 }
 297 #undef FUNC_NAME
 298
 299 SCM_DEFINE (scm_system_async, "system-async", 1, 0, 0,
 300             (SCM thunk),
 301 "")
 302 #define FUNC_NAME s_scm_system_async
 303 {
 304   SCM it;
 305   SCM list;
 306
 307   it = scm_async (thunk);
 308   SCM_NEWCELL (list);
 309   SCM_SETCAR (list, it);
 310   SCM_SETCDR (list, scm_asyncs);
 311   scm_asyncs = list;
 312   return it;
 313 }
 314 #undef FUNC_NAME
 315
 316 SCM_DEFINE (scm_async_mark, "async-mark", 1, 0, 0,
 317             (SCM a),
 318 "")
 319 #define FUNC_NAME s_scm_async_mark
 320 {
 321   VALIDATE_ASYNC (1, a);
 322 #ifdef GUILE_OLD_ASYNC_CLICK
 323   SET_ASYNC_GOT_IT (a, 1);
 324 #else
 325   SET_ASYNC_GOT_IT (a, scm_asyncs_pending_p = 1);
 326 #endif
 327   return SCM_UNSPECIFIED;
 328 }
 329 #undef FUNC_NAME
 330
 331
 332 SCM_DEFINE (scm_system_async_mark, "system-async-mark", 1, 0, 0,
 333            (SCM a),
 334 "")
 335 #define FUNC_NAME s_scm_system_async_mark
 336 {
 337   VALIDATE_ASYNC (1, a);
 338   SCM_REDEFER_INTS;
 339 #ifdef GUILE_OLD_ASYNC_CLICK
 340   SET_ASYNC_GOT_IT (a, 1);
 341   scm_async_rate = 1 + scm_async_rate - scm_async_clock;
 342   scm_async_clock = 1;
 343 #else
 344   SET_ASYNC_GOT_IT (a, scm_asyncs_pending_p = 1);
 345 #endif
 346   SCM_REALLOW_INTS;
 347   return SCM_UNSPECIFIED;
 348 }
 349 #undef FUNC_NAME
 350
 351
 352 SCM_DEFINE (scm_run_asyncs, "run-asyncs", 1, 0, 0,
 353            (SCM list_of_a),
 354 "")
 355 #define FUNC_NAME s_scm_run_asyncs
 356 {
 357 #ifdef GUILE_OLD_ASYNC_CLICK
 358   if (scm_mask_ints)
 359     return SCM_BOOL_F;
 360 #else
 361   scm_asyncs_pending_p = 0;
 362 #endif
 363   while (! SCM_NULLP (list_of_a))
 364     {
 365       SCM a;
 366       SCM_VALIDATE_CONS (1, list_of_a);
 367       a = SCM_CAR (list_of_a);
 368       VALIDATE_ASYNC (SCM_ARG1, a);
 369       scm_mask_ints = 1;
 370       if (ASYNC_GOT_IT (a))
 371         {
 372           SET_ASYNC_GOT_IT (a, 0);
 373           scm_apply (ASYNC_THUNK (a), SCM_EOL, SCM_EOL);
 374         }
 375       scm_mask_ints = 0;
 376       list_of_a = SCM_CDR (list_of_a);
 377     }
 378   return SCM_BOOL_T;
 379 }
 380 #undef FUNC_NAME
 381
 382 \f
 383
 384
 385 SCM_DEFINE (scm_noop, "noop", 0, 0, 1,
 386            (SCM args),
 387 "")
 388 #define FUNC_NAME s_scm_noop
 389 {
 390   SCM_VALIDATE_REST_ARGUMENT (args);
 391   return (SCM_NULLP (args) ? SCM_BOOL_F : SCM_CAR (args));
 392 }
 393 #undef FUNC_NAME
 394
 395
 396 \f
 397
 398 #ifdef GUILE_OLD_ASYNC_CLICK
 399
 400 SCM_DEFINE (scm_set_tick_rate, "set-tick-rate", 1, 0, 0,
 401            (SCM n),
 402 "")
 403 #define FUNC_NAME s_scm_set_tick_rate
 404 {
 405   unsigned int old_n = scm_tick_rate;
 406   SCM_VALIDATE_INUM (1, n);
 407   scm_desired_tick_rate = SCM_INUM (n);
 408   scm_async_rate = 1 + scm_async_rate - scm_async_clock;
 409   scm_async_clock = 1;
 410   return SCM_MAKINUM (old_n);
 411 }
 412 #undef FUNC_NAME
 413
 414 \f
 415
 416
 417 SCM_DEFINE (scm_set_switch_rate, "set-switch-rate", 1, 0, 0,
 418            (SCM n),
 419 "")
 420 #define FUNC_NAME s_scm_set_switch_rate
 421 {
 422   unsigned int old_n = scm_switch_rate;
 423   SCM_VALIDATE_INUM (1, n);
 424   scm_desired_switch_rate = SCM_INUM (n);
 425   scm_async_rate = 1 + scm_async_rate - scm_async_clock;
 426   scm_async_clock = 1;
 427   return SCM_MAKINUM (old_n);
 428 }
 429 #undef FUNC_NAME
 430
 431 #endif
 432
 433 \f
 434
 435 SCM_DEFINE (scm_unmask_signals, "unmask-signals", 0, 0, 0,
 436            (),
 437 "")
 438 #define FUNC_NAME s_scm_unmask_signals
 439 {
 440   scm_mask_ints = 0;
 441   return SCM_UNSPECIFIED;
 442 }
 443 #undef FUNC_NAME
 444
 445
 446 SCM_DEFINE (scm_mask_signals, "mask-signals", 0, 0, 0,
 447            (),
 448 "")
 449 #define FUNC_NAME s_scm_mask_signals
 450 {
 451   scm_mask_ints = 1;
 452   return SCM_UNSPECIFIED;
 453 }
 454 #undef FUNC_NAME
 455
 456 \f
 457
 458 void
 459 scm_init_async ()
 460 {
 461   scm_asyncs = SCM_EOL;
 462   tc16_async = scm_make_smob_type ("async", 0);
 463   scm_set_smob_mark (tc16_async, mark_async);
 464
 465 #ifndef SCM_MAGIC_SNARFER
 466 #include "libguile/async.x"
 467 #endif
 468 }
 469
 470 /*
 471   Local Variables:
 472   c-file-style: "gnu"
 473   End:
 474 */