external/public-domain/xz/dist/src/common/mythread.h

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       mythread.h
   4 /// \brief      Some threading related helper macros and functions
   5 //
   6 //  Author:     Lasse Collin
   7 //
   8 //  This file has been put into the public domain.
   9 //  You can do whatever you want with this file.
  10 //
  11 ///////////////////////////////////////////////////////////////////////////////
  12
  13 #ifndef MYTHREAD_H
  14 #define MYTHREAD_H
  15
  16 #include "sysdefs.h"
  17
  18 // If any type of threading is enabled, #define MYTHREAD_ENABLED.
  19 #if defined(MYTHREAD_POSIX) || defined(MYTHREAD_WIN95) \
  20                 || defined(MYTHREAD_VISTA)
  21 #       define MYTHREAD_ENABLED 1
  22 #endif
  23
  24
  25 #ifdef MYTHREAD_ENABLED
  26
  27 ////////////////////////////////////////
  28 // Shared between all threading types //
  29 ////////////////////////////////////////
  30
  31 // Locks a mutex for a duration of a block.
  32 //
  33 // Perform mythread_mutex_lock(&mutex) in the beginning of a block
  34 // and mythread_mutex_unlock(&mutex) at the end of the block. "break"
  35 // may be used to unlock the mutex and jump out of the block.
  36 // mythread_sync blocks may be nested.
  37 //
  38 // Example:
  39 //
  40 //     mythread_sync(mutex) {
  41 //         foo();
  42 //         if (some_error)
  43 //             break; // Skips bar()
  44 //         bar();
  45 //     }
  46 //
  47 // At least GCC optimizes the loops completely away so it doesn't slow
  48 // things down at all compared to plain mythread_mutex_lock(&mutex)
  49 // and mythread_mutex_unlock(&mutex) calls.
  50 //
  51 #define mythread_sync(mutex) mythread_sync_helper1(mutex, __LINE__)
  52 #define mythread_sync_helper1(mutex, line) mythread_sync_helper2(mutex, line)
  53 #define mythread_sync_helper2(mutex, line) \
  54         for (unsigned int mythread_i_ ## line = 0; \
  55                         mythread_i_ ## line \
  56                                 ? (mythread_mutex_unlock(&(mutex)), 0) \
  57                                 : (mythread_mutex_lock(&(mutex)), 1); \
  58                         mythread_i_ ## line = 1) \
  59                 for (unsigned int mythread_j_ ## line = 0; \
  60                                 !mythread_j_ ## line; \
  61                                 mythread_j_ ## line = 1)
  62 #endif
  63
  64
  65 #if !defined(MYTHREAD_ENABLED)
  66
  67 //////////////////
  68 // No threading //
  69 //////////////////
  70
  71 // Calls the given function once. This isn't thread safe.
  72 #define mythread_once(func) \
  73 do { \
  74         static bool once_ = false; \
  75         if (!once_) { \
  76                 func(); \
  77                 once_ = true; \
  78         } \
  79 } while (0)
  80
  81
  82 #if !(defined(_WIN32) && !defined(__CYGWIN__))
  83 // Use sigprocmask() to set the signal mask in single-threaded programs.
  84 #include <signal.h>
  85
  86 static inline void
  87 mythread_sigmask(int how, const sigset_t *restrict set,
  88                 sigset_t *restrict oset)
  89 {
  90         int ret = sigprocmask(how, set, oset);
  91         assert(ret == 0);
  92         (void)ret;
  93 }
  94 #endif
  95
  96
  97 #elif defined(MYTHREAD_POSIX)
  98
  99 ////////////////////
 100 // Using pthreads //
 101 ////////////////////
 102
 103 #include <sys/time.h>
 104 #include <pthread.h>
 105 #include <signal.h>
 106 #include <time.h>
 107 #include <errno.h>
 108
 109 #define MYTHREAD_RET_TYPE void *
 110 #define MYTHREAD_RET_VALUE NULL
 111
 112 typedef pthread_t mythread;
 113 typedef pthread_mutex_t mythread_mutex;
 114
 115 typedef struct {
 116         pthread_cond_t cond;
 117 #ifdef HAVE_CLOCK_GETTIME
 118         // Clock ID (CLOCK_REALTIME or CLOCK_MONOTONIC) associated with
 119         // the condition variable.
 120         clockid_t clk_id;
 121 #endif
 122 } mythread_cond;
 123
 124 typedef struct timespec mythread_condtime;
 125
 126
 127 // Calls the given function once in a thread-safe way.
 128 #define mythread_once(func) \
 129         do { \
 130                 static pthread_once_t once_ = PTHREAD_ONCE_INIT; \
 131                 pthread_once(&once_, &func); \
 132         } while (0)
 133
 134
 135 // Use pthread_sigmask() to set the signal mask in multi-threaded programs.
 136 // Do nothing on OpenVMS since it lacks pthread_sigmask().
 137 static inline void
 138 mythread_sigmask(int how, const sigset_t *restrict set,
 139                 sigset_t *restrict oset)
 140 {
 141 #ifdef __VMS
 142         (void)how;
 143         (void)set;
 144         (void)oset;
 145 #else
 146         int ret = pthread_sigmask(how, set, oset);
 147         assert(ret == 0);
 148         (void)ret;
 149 #endif
 150 }
 151
 152
 153 // Creates a new thread with all signals blocked. Returns zero on success
 154 // and non-zero on error.
 155 static inline int
 156 mythread_create(mythread *thread, void *(*func)(void *arg), void *arg)
 157 {
 158         sigset_t old;
 159         sigset_t all;
 160         sigfillset(&all);
 161
 162         mythread_sigmask(SIG_SETMASK, &all, &old);
 163         const int ret = pthread_create(thread, NULL, func, arg);
 164         mythread_sigmask(SIG_SETMASK, &old, NULL);
 165
 166         return ret;
 167 }
 168
 169 // Joins a thread. Returns zero on success and non-zero on error.
 170 static inline int
 171 mythread_join(mythread thread)
 172 {
 173         return pthread_join(thread, NULL);
 174 }
 175
 176
 177 // Initiatlizes a mutex. Returns zero on success and non-zero on error.
 178 static inline int
 179 mythread_mutex_init(mythread_mutex *mutex)
 180 {
 181         return pthread_mutex_init(mutex, NULL);
 182 }
 183
 184 static inline void
 185 mythread_mutex_destroy(mythread_mutex *mutex)
 186 {
 187         int ret = pthread_mutex_destroy(mutex);
 188         assert(ret == 0);
 189         (void)ret;
 190 }
 191
 192 static inline void
 193 mythread_mutex_lock(mythread_mutex *mutex)
 194 {
 195         int ret = pthread_mutex_lock(mutex);
 196         assert(ret == 0);
 197         (void)ret;
 198 }
 199
 200 static inline void
 201 mythread_mutex_unlock(mythread_mutex *mutex)
 202 {
 203         int ret = pthread_mutex_unlock(mutex);
 204         assert(ret == 0);
 205         (void)ret;
 206 }
 207
 208
 209 // Initializes a condition variable.
 210 //
 211 // Using CLOCK_MONOTONIC instead of the default CLOCK_REALTIME makes the
 212 // timeout in pthread_cond_timedwait() work correctly also if system time
 213 // is suddenly changed. Unfortunately CLOCK_MONOTONIC isn't available
 214 // everywhere while the default CLOCK_REALTIME is, so the default is
 215 // used if CLOCK_MONOTONIC isn't available.
 216 //
 217 // If clock_gettime() isn't available at all, gettimeofday() will be used.
 218 static inline int
 219 mythread_cond_init(mythread_cond *mycond)
 220 {
 221 #ifdef HAVE_CLOCK_GETTIME
 222         // NOTE: HAVE_DECL_CLOCK_MONOTONIC is always defined to 0 or 1.
 223 #       if defined(HAVE_PTHREAD_CONDATTR_SETCLOCK) && HAVE_DECL_CLOCK_MONOTONIC
 224         struct timespec ts;
 225         pthread_condattr_t condattr;
 226
 227         // POSIX doesn't seem to *require* that pthread_condattr_setclock()
 228         // will fail if given an unsupported clock ID. Test that
 229         // CLOCK_MONOTONIC really is supported using clock_gettime().
 230         if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0
 231                         && pthread_condattr_init(&condattr) == 0) {
 232                 int ret = pthread_condattr_setclock(
 233                                 &condattr, CLOCK_MONOTONIC);
 234                 if (ret == 0)
 235                         ret = pthread_cond_init(&mycond->cond, &condattr);
 236
 237                 pthread_condattr_destroy(&condattr);
 238
 239                 if (ret == 0) {
 240                         mycond->clk_id = CLOCK_MONOTONIC;
 241                         return 0;
 242                 }
 243         }
 244
 245         // If anything above fails, fall back to the default CLOCK_REALTIME.
 246         // POSIX requires that all implementations of clock_gettime() must
 247         // support at least CLOCK_REALTIME.
 248 #       endif
 249
 250         mycond->clk_id = CLOCK_REALTIME;
 251 #endif
 252
 253         return pthread_cond_init(&mycond->cond, NULL);
 254 }
 255
 256 static inline void
 257 mythread_cond_destroy(mythread_cond *cond)
 258 {
 259         int ret = pthread_cond_destroy(&cond->cond);
 260         assert(ret == 0);
 261         (void)ret;
 262 }
 263
 264 static inline void
 265 mythread_cond_signal(mythread_cond *cond)
 266 {
 267         int ret = pthread_cond_signal(&cond->cond);
 268         assert(ret == 0);
 269         (void)ret;
 270 }
 271
 272 static inline void
 273 mythread_cond_wait(mythread_cond *cond, mythread_mutex *mutex)
 274 {
 275         int ret = pthread_cond_wait(&cond->cond, mutex);
 276         assert(ret == 0);
 277         (void)ret;
 278 }
 279
 280 // Waits on a condition or until a timeout expires. If the timeout expires,
 281 // non-zero is returned, otherwise zero is returned.
 282 static inline int
 283 mythread_cond_timedwait(mythread_cond *cond, mythread_mutex *mutex,
 284                 const mythread_condtime *condtime)
 285 {
 286         int ret = pthread_cond_timedwait(&cond->cond, mutex, condtime);
 287         assert(ret == 0 || ret == ETIMEDOUT);
 288         return ret;
 289 }
 290
 291 // Sets condtime to the absolute time that is timeout_ms milliseconds
 292 // in the future. The type of the clock to use is taken from cond.
 293 static inline void
 294 mythread_condtime_set(mythread_condtime *condtime, const mythread_cond *cond,
 295                 uint32_t timeout_ms)
 296 {
 297         condtime->tv_sec = timeout_ms / 1000;
 298         condtime->tv_nsec = (timeout_ms % 1000) * 1000000;
 299
 300 #ifdef HAVE_CLOCK_GETTIME
 301         struct timespec now;
 302         int ret = clock_gettime(cond->clk_id, &now);
 303         assert(ret == 0);
 304         (void)ret;
 305
 306         condtime->tv_sec += now.tv_sec;
 307         condtime->tv_nsec += now.tv_nsec;
 308 #else
 309         (void)cond;
 310
 311         struct timeval now;
 312         gettimeofday(&now, NULL);
 313
 314         condtime->tv_sec += now.tv_sec;
 315         condtime->tv_nsec += now.tv_usec * 1000L;
 316 #endif
 317
 318         // tv_nsec must stay in the range [0, 999_999_999].
 319         if (condtime->tv_nsec >= 1000000000L) {
 320                 condtime->tv_nsec -= 1000000000L;
 321                 ++condtime->tv_sec;
 322         }
 323 }
 324
 325
 326 #elif defined(MYTHREAD_WIN95) || defined(MYTHREAD_VISTA)
 327
 328 /////////////////////
 329 // Windows threads //
 330 /////////////////////
 331
 332 #define WIN32_LEAN_AND_MEAN
 333 #ifdef MYTHREAD_VISTA
 334 #       undef _WIN32_WINNT
 335 #       define _WIN32_WINNT 0x0600
 336 #endif
 337 #include <windows.h>
 338 #include <process.h>
 339
 340 #define MYTHREAD_RET_TYPE unsigned int __stdcall
 341 #define MYTHREAD_RET_VALUE 0
 342
 343 typedef HANDLE mythread;
 344 typedef CRITICAL_SECTION mythread_mutex;
 345
 346 #ifdef MYTHREAD_WIN95
 347 typedef HANDLE mythread_cond;
 348 #else
 349 typedef CONDITION_VARIABLE mythread_cond;
 350 #endif
 351
 352 typedef struct {
 353         // Tick count (milliseconds) in the beginning of the timeout.
 354         // NOTE: This is 32 bits so it wraps around after 49.7 days.
 355         // Multi-day timeouts may not work as expected.
 356         DWORD start;
 357
 358         // Length of the timeout in milliseconds. The timeout expires
 359         // when the current tick count minus "start" is equal or greater
 360         // than "timeout".
 361         DWORD timeout;
 362 } mythread_condtime;
 363
 364
 365 // mythread_once() is only available with Vista threads.
 366 #ifdef MYTHREAD_VISTA
 367 #define mythread_once(func) \
 368         do { \
 369                 static INIT_ONCE once_ = INIT_ONCE_STATIC_INIT; \
 370                 BOOL pending_; \
 371                 if (!InitOnceBeginInitialize(&once_, 0, &pending_, NULL)) \
 372                         abort(); \
 373                 if (pending_) \
 374                         func(); \
 375                 if (!InitOnceComplete(&once, 0, NULL)) \
 376                         abort(); \
 377         } while (0)
 378 #endif
 379
 380
 381 // mythread_sigmask() isn't available on Windows. Even a dummy version would
 382 // make no sense because the other POSIX signal functions are missing anyway.
 383
 384
 385 static inline int
 386 mythread_create(mythread *thread,
 387                 unsigned int (__stdcall *func)(void *arg), void *arg)
 388 {
 389         uintptr_t ret = _beginthreadex(NULL, 0, func, arg, 0, NULL);
 390         if (ret == 0)
 391                 return -1;
 392
 393         *thread = (HANDLE)ret;
 394         return 0;
 395 }
 396
 397 static inline int
 398 mythread_join(mythread thread)
 399 {
 400         int ret = 0;
 401
 402         if (WaitForSingleObject(thread, INFINITE) != WAIT_OBJECT_0)
 403                 ret = -1;
 404
 405         if (!CloseHandle(thread))
 406                 ret = -1;
 407
 408         return ret;
 409 }
 410
 411
 412 static inline int
 413 mythread_mutex_init(mythread_mutex *mutex)
 414 {
 415         InitializeCriticalSection(mutex);
 416         return 0;
 417 }
 418
 419 static inline void
 420 mythread_mutex_destroy(mythread_mutex *mutex)
 421 {
 422         DeleteCriticalSection(mutex);
 423 }
 424
 425 static inline void
 426 mythread_mutex_lock(mythread_mutex *mutex)
 427 {
 428         EnterCriticalSection(mutex);
 429 }
 430
 431 static inline void
 432 mythread_mutex_unlock(mythread_mutex *mutex)
 433 {
 434         LeaveCriticalSection(mutex);
 435 }
 436
 437
 438 static inline int
 439 mythread_cond_init(mythread_cond *cond)
 440 {
 441 #ifdef MYTHREAD_WIN95
 442         *cond = CreateEvent(NULL, FALSE, FALSE, NULL);
 443         return *cond == NULL ? -1 : 0;
 444 #else
 445         InitializeConditionVariable(cond);
 446         return 0;
 447 #endif
 448 }
 449
 450 static inline void
 451 mythread_cond_destroy(mythread_cond *cond)
 452 {
 453 #ifdef MYTHREAD_WIN95
 454         CloseHandle(*cond);
 455 #else
 456         (void)cond;
 457 #endif
 458 }
 459
 460 static inline void
 461 mythread_cond_signal(mythread_cond *cond)
 462 {
 463 #ifdef MYTHREAD_WIN95
 464         SetEvent(*cond);
 465 #else
 466         WakeConditionVariable(cond);
 467 #endif
 468 }
 469
 470 static inline void
 471 mythread_cond_wait(mythread_cond *cond, mythread_mutex *mutex)
 472 {
 473 #ifdef MYTHREAD_WIN95
 474         LeaveCriticalSection(mutex);
 475         WaitForSingleObject(*cond, INFINITE);
 476         EnterCriticalSection(mutex);
 477 #else
 478         BOOL ret = SleepConditionVariableCS(cond, mutex, INFINITE);
 479         assert(ret);
 480         (void)ret;
 481 #endif
 482 }
 483
 484 static inline int
 485 mythread_cond_timedwait(mythread_cond *cond, mythread_mutex *mutex,
 486                 const mythread_condtime *condtime)
 487 {
 488 #ifdef MYTHREAD_WIN95
 489         LeaveCriticalSection(mutex);
 490 #endif
 491
 492         DWORD elapsed = GetTickCount() - condtime->start;
 493         DWORD timeout = elapsed >= condtime->timeout
 494                         ? 0 : condtime->timeout - elapsed;
 495
 496 #ifdef MYTHREAD_WIN95
 497         DWORD ret = WaitForSingleObject(*cond, timeout);
 498         assert(ret == WAIT_OBJECT_0 || ret == WAIT_TIMEOUT);
 499
 500         EnterCriticalSection(mutex);
 501
 502         return ret == WAIT_TIMEOUT;
 503 #else
 504         BOOL ret = SleepConditionVariableCS(cond, mutex, timeout);
 505         assert(ret || GetLastError() == ERROR_TIMEOUT);
 506         return !ret;
 507 #endif
 508 }
 509
 510 static inline void
 511 mythread_condtime_set(mythread_condtime *condtime, const mythread_cond *cond,
 512                 uint32_t timeout)
 513 {
 514         (void)cond;
 515         condtime->start = GetTickCount();
 516         condtime->timeout = timeout;
 517 }
 518
 519 #endif
 520
 521 #endif