--- /dev/null
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \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.
+#include <signal.h>
+
+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
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