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///////////////////////////////////////////////////////////////////////////////
//
/// \file mythread.h
/// \brief Some threading related helper macros and functions
//
// Author: Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#ifndef MYTHREAD_H
#define MYTHREAD_H
#include "sysdefs.h"
// If any type of threading is enabled, #define MYTHREAD_ENABLED.
#if defined(MYTHREAD_POSIX) || defined(MYTHREAD_WIN95) \
|| defined(MYTHREAD_VISTA)
# define MYTHREAD_ENABLED 1
#endif
#ifdef MYTHREAD_ENABLED
////////////////////////////////////////
// Shared between all threading types //
////////////////////////////////////////
// Locks a mutex for a duration of a block.
//
// Perform mythread_mutex_lock(&mutex) in the beginning of a block
// and mythread_mutex_unlock(&mutex) at the end of the block. "break"
// may be used to unlock the mutex and jump out of the block.
// mythread_sync blocks may be nested.
//
// Example:
//
// mythread_sync(mutex) {
// foo();
// if (some_error)
// break; // Skips bar()
// bar();
// }
//
// At least GCC optimizes the loops completely away so it doesn't slow
// things down at all compared to plain mythread_mutex_lock(&mutex)
// and mythread_mutex_unlock(&mutex) calls.
//
#define mythread_sync(mutex) mythread_sync_helper1(mutex, __LINE__)
#define mythread_sync_helper1(mutex, line) mythread_sync_helper2(mutex, line)
#define mythread_sync_helper2(mutex, line) \
for (unsigned int mythread_i_ ## line = 0; \
mythread_i_ ## line \
? (mythread_mutex_unlock(&(mutex)), 0) \
: (mythread_mutex_lock(&(mutex)), 1); \
mythread_i_ ## line = 1) \
for (unsigned int mythread_j_ ## line = 0; \
!mythread_j_ ## line; \
mythread_j_ ## line = 1)
#endif
#if !defined(MYTHREAD_ENABLED)
//////////////////
// No threading //
//////////////////
// Calls the given function once. This isn't thread safe.
#define mythread_once(func) \
do { \
static bool once_ = false; \
if (!once_) { \
func(); \
once_ = true; \
} \
} while (0)
#if !(defined(_WIN32) && !defined(__CYGWIN__))
// Use sigprocmask() to set the signal mask in single-threaded programs.
static inline void
mythread_sigmask(int how, const sigset_t *restrict set,
sigset_t *restrict oset)
{
int ret = sigprocmask(how, set, oset);
assert(ret == 0);
(void)ret;
}
#endif
#elif defined(MYTHREAD_POSIX)
////////////////////
// Using pthreads //
////////////////////
#include <sys/time.h>
#include <pthread.h>
#include <signal.h>
#include <time.h>
#include <errno.h>
#define MYTHREAD_RET_TYPE void *
#define MYTHREAD_RET_VALUE NULL
typedef pthread_t mythread;
typedef pthread_mutex_t mythread_mutex;
typedef struct {
pthread_cond_t cond;
#ifdef HAVE_CLOCK_GETTIME
// Clock ID (CLOCK_REALTIME or CLOCK_MONOTONIC) associated with
// the condition variable.
clockid_t clk_id;
#endif
} mythread_cond;
typedef struct timespec mythread_condtime;
// Calls the given function once in a thread-safe way.
#define mythread_once(func) \
do { \
static pthread_once_t once_ = PTHREAD_ONCE_INIT; \
pthread_once(&once_, &func); \
} while (0)
// Use pthread_sigmask() to set the signal mask in multi-threaded programs.
// Do nothing on OpenVMS since it lacks pthread_sigmask().
static inline void
mythread_sigmask(int how, const sigset_t *restrict set,
sigset_t *restrict oset)
{
#ifdef __VMS
(void)how;
(void)set;
(void)oset;
#else
int ret = pthread_sigmask(how, set, oset);
assert(ret == 0);
(void)ret;
#endif
}
// Creates a new thread with all signals blocked. Returns zero on success
// and non-zero on error.
static inline int
mythread_create(mythread *thread, void *(*func)(void *arg), void *arg)
{
sigset_t old;
sigset_t all;
sigfillset(&all);
mythread_sigmask(SIG_SETMASK, &all, &old);
const int ret = pthread_create(thread, NULL, func, arg);
mythread_sigmask(SIG_SETMASK, &old, NULL);
return ret;
}
// Joins a thread. Returns zero on success and non-zero on error.
static inline int
mythread_join(mythread thread)
{
return pthread_join(thread, NULL);
}
// Initiatlizes a mutex. Returns zero on success and non-zero on error.
static inline int
mythread_mutex_init(mythread_mutex *mutex)
{
return pthread_mutex_init(mutex, NULL);
}
static inline void
mythread_mutex_destroy(mythread_mutex *mutex)
{
int ret = pthread_mutex_destroy(mutex);
assert(ret == 0);
(void)ret;
}
static inline void
mythread_mutex_lock(mythread_mutex *mutex)
{
int ret = pthread_mutex_lock(mutex);
assert(ret == 0);
(void)ret;
}
static inline void
mythread_mutex_unlock(mythread_mutex *mutex)
{
int ret = pthread_mutex_unlock(mutex);
assert(ret == 0);
(void)ret;
}
// Initializes a condition variable.
//
// Using CLOCK_MONOTONIC instead of the default CLOCK_REALTIME makes the
// timeout in pthread_cond_timedwait() work correctly also if system time
// is suddenly changed. Unfortunately CLOCK_MONOTONIC isn't available
// everywhere while the default CLOCK_REALTIME is, so the default is
// used if CLOCK_MONOTONIC isn't available.
//
// If clock_gettime() isn't available at all, gettimeofday() will be used.
static inline int
mythread_cond_init(mythread_cond *mycond)
{
#ifdef HAVE_CLOCK_GETTIME
// NOTE: HAVE_DECL_CLOCK_MONOTONIC is always defined to 0 or 1.
# if defined(HAVE_PTHREAD_CONDATTR_SETCLOCK) && HAVE_DECL_CLOCK_MONOTONIC
struct timespec ts;
pthread_condattr_t condattr;
// POSIX doesn't seem to *require* that pthread_condattr_setclock()
// will fail if given an unsupported clock ID. Test that
// CLOCK_MONOTONIC really is supported using clock_gettime().
if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0
&& pthread_condattr_init(&condattr) == 0) {
int ret = pthread_condattr_setclock(
&condattr, CLOCK_MONOTONIC);
if (ret == 0)
ret = pthread_cond_init(&mycond->cond, &condattr);
pthread_condattr_destroy(&condattr);
if (ret == 0) {
mycond->clk_id = CLOCK_MONOTONIC;
return 0;
}
}
// If anything above fails, fall back to the default CLOCK_REALTIME.
// POSIX requires that all implementations of clock_gettime() must
// support at least CLOCK_REALTIME.
# endif
mycond->clk_id = CLOCK_REALTIME;
#endif
return pthread_cond_init(&mycond->cond, NULL);
}
static inline void
mythread_cond_destroy(mythread_cond *cond)
{
int ret = pthread_cond_destroy(&cond->cond);
assert(ret == 0);
(void)ret;
}
static inline void
mythread_cond_signal(mythread_cond *cond)
{
int ret = pthread_cond_signal(&cond->cond);
assert(ret == 0);
(void)ret;
}
static inline void
mythread_cond_wait(mythread_cond *cond, mythread_mutex *mutex)
{
int ret = pthread_cond_wait(&cond->cond, mutex);
assert(ret == 0);
(void)ret;
}
// Waits on a condition or until a timeout expires. If the timeout expires,
// non-zero is returned, otherwise zero is returned.
static inline int
mythread_cond_timedwait(mythread_cond *cond, mythread_mutex *mutex,
const mythread_condtime *condtime)
{
int ret = pthread_cond_timedwait(&cond->cond, mutex, condtime);
assert(ret == 0 || ret == ETIMEDOUT);
return ret;
}
// Sets condtime to the absolute time that is timeout_ms milliseconds
// in the future. The type of the clock to use is taken from cond.
static inline void
mythread_condtime_set(mythread_condtime *condtime, const mythread_cond *cond,
uint32_t timeout_ms)
{
condtime->tv_sec = timeout_ms / 1000;
condtime->tv_nsec = (timeout_ms % 1000) * 1000000;
#ifdef HAVE_CLOCK_GETTIME
struct timespec now;
int ret = clock_gettime(cond->clk_id, &now);
assert(ret == 0);
(void)ret;
condtime->tv_sec += now.tv_sec;
condtime->tv_nsec += now.tv_nsec;
#else
(void)cond;
struct timeval now;
gettimeofday(&now, NULL);
condtime->tv_sec += now.tv_sec;
condtime->tv_nsec += now.tv_usec * 1000L;
#endif
// tv_nsec must stay in the range [0, 999_999_999].
if (condtime->tv_nsec >= 1000000000L) {
condtime->tv_nsec -= 1000000000L;
++condtime->tv_sec;
}
}
#elif defined(MYTHREAD_WIN95) || defined(MYTHREAD_VISTA)
/////////////////////
// Windows threads //
/////////////////////
#define WIN32_LEAN_AND_MEAN
#ifdef MYTHREAD_VISTA
# undef _WIN32_WINNT
# define _WIN32_WINNT 0x0600
#endif
#include <windows.h>
#include <process.h>
#define MYTHREAD_RET_TYPE unsigned int __stdcall
#define MYTHREAD_RET_VALUE 0
typedef HANDLE mythread;
typedef CRITICAL_SECTION mythread_mutex;
#ifdef MYTHREAD_WIN95
typedef HANDLE mythread_cond;
#else
typedef CONDITION_VARIABLE mythread_cond;
#endif
typedef struct {
// Tick count (milliseconds) in the beginning of the timeout.
// NOTE: This is 32 bits so it wraps around after 49.7 days.
// Multi-day timeouts may not work as expected.
DWORD start;
// Length of the timeout in milliseconds. The timeout expires
// when the current tick count minus "start" is equal or greater
// than "timeout".
DWORD timeout;
} mythread_condtime;
// mythread_once() is only available with Vista threads.
#ifdef MYTHREAD_VISTA
#define mythread_once(func) \
do { \
static INIT_ONCE once_ = INIT_ONCE_STATIC_INIT; \
BOOL pending_; \
if (!InitOnceBeginInitialize(&once_, 0, &pending_, NULL)) \
abort(); \
if (pending_) \
func(); \
if (!InitOnceComplete(&once, 0, NULL)) \
abort(); \
} while (0)
#endif
// mythread_sigmask() isn't available on Windows. Even a dummy version would
// make no sense because the other POSIX signal functions are missing anyway.
static inline int
mythread_create(mythread *thread,
unsigned int (__stdcall *func)(void *arg), void *arg)
{
uintptr_t ret = _beginthreadex(NULL, 0, func, arg, 0, NULL);
if (ret == 0)
return -1;
*thread = (HANDLE)ret;
return 0;
}
static inline int
mythread_join(mythread thread)
{
int ret = 0;
if (WaitForSingleObject(thread, INFINITE) != WAIT_OBJECT_0)
ret = -1;
if (!CloseHandle(thread))
ret = -1;
return ret;
}
static inline int
mythread_mutex_init(mythread_mutex *mutex)
{
InitializeCriticalSection(mutex);
return 0;
}
static inline void
mythread_mutex_destroy(mythread_mutex *mutex)
{
DeleteCriticalSection(mutex);
}
static inline void
mythread_mutex_lock(mythread_mutex *mutex)
{
EnterCriticalSection(mutex);
}
static inline void
mythread_mutex_unlock(mythread_mutex *mutex)
{
LeaveCriticalSection(mutex);
}
static inline int
mythread_cond_init(mythread_cond *cond)
{
#ifdef MYTHREAD_WIN95
*cond = CreateEvent(NULL, FALSE, FALSE, NULL);
return *cond == NULL ? -1 : 0;
#else
InitializeConditionVariable(cond);
return 0;
#endif
}
static inline void
mythread_cond_destroy(mythread_cond *cond)
{
#ifdef MYTHREAD_WIN95
CloseHandle(*cond);
#else
(void)cond;
#endif
}
static inline void
mythread_cond_signal(mythread_cond *cond)
{
#ifdef MYTHREAD_WIN95
SetEvent(*cond);
#else
WakeConditionVariable(cond);
#endif
}
static inline void
mythread_cond_wait(mythread_cond *cond, mythread_mutex *mutex)
{
#ifdef MYTHREAD_WIN95
LeaveCriticalSection(mutex);
WaitForSingleObject(*cond, INFINITE);
EnterCriticalSection(mutex);
#else
BOOL ret = SleepConditionVariableCS(cond, mutex, INFINITE);
assert(ret);
(void)ret;
#endif
}
static inline int
mythread_cond_timedwait(mythread_cond *cond, mythread_mutex *mutex,
const mythread_condtime *condtime)
{
#ifdef MYTHREAD_WIN95
LeaveCriticalSection(mutex);
#endif
DWORD elapsed = GetTickCount() - condtime->start;
DWORD timeout = elapsed >= condtime->timeout
? 0 : condtime->timeout - elapsed;
#ifdef MYTHREAD_WIN95
DWORD ret = WaitForSingleObject(*cond, timeout);
assert(ret == WAIT_OBJECT_0 || ret == WAIT_TIMEOUT);
EnterCriticalSection(mutex);
return ret == WAIT_TIMEOUT;
#else
BOOL ret = SleepConditionVariableCS(cond, mutex, timeout);
assert(ret || GetLastError() == ERROR_TIMEOUT);
return !ret;
#endif
}
static inline void
mythread_condtime_set(mythread_condtime *condtime, const mythread_cond *cond,
uint32_t timeout)
{
(void)cond;
condtime->start = GetTickCount();
condtime->timeout = timeout;
}
#endif
#endif