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Implement condition variables for Windows

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This commit is contained in:
Chris Robinson 2014-05-27 04:59:43 -07:00
parent 2d2bc25fd0
commit f0b65aa6b7
2 changed files with 170 additions and 10 deletions
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158
common/threads.c
View File

@ -230,6 +230,164 @@ int almtx_timedlock(almtx_t *mtx, const struct timespec *ts)
return ret;
}
#if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x0600
int alcnd_init(alcnd_t *cond)
{
InitializeConditionVariable(cond);
return althrd_success;
}
int alcnd_signal(alcnd_t *cond)
{
WakeConditionVariable(cond);
return althrd_success;
}
int alcnd_broadcast(alcnd_t *cond)
{
WakeAllConditionVariable(cond);
return althrd_success;
}
int alcnd_wait(alcnd_t *cond, almtx_t *mtx)
{
if(SleepConditionVariableCS(cond, mtx, INFINITE) != 0)
return althrd_success;
return althrd_error;
}
int alcnd_timedwait(alcnd_t *cond, almtx_t *mtx, const struct timespec *time_point)
{
struct timespec curtime;
DWORD sleeptime;
if(altimespec_get(&curtime, AL_TIME_UTC) != AL_TIME_UTC)
return althrd_error;
sleeptime = (time_point->tv_nsec - curtime.tv_nsec + 999999)/1000000;
sleeptime += (time_point->tv_sec - curtime.tv_sec)*1000;
if(SleepConditionVariableCS(cond, mtx, sleeptime) != 0)
return althrd_success;
return (GetLastError()==ERROR_TIMEOUT) ? althrd_timedout : althrd_error;
}
void alcnd_destroy(alcnd_t* UNUSED(cond))
{
/* Nothing to delete? */
}
#else
/* WARNING: This is a rather poor implementation of condition variables, with
* known problems. However, it's simple, efficient, and good enough for now to
* not require Vista. Based on "Strategies for Implementing POSIX Condition
* Variables" by Douglas C. Schmidt and Irfan Pyarali:
* http://www.cs.wustl.edu/~schmidt/win32-cv-1.html
*/
/* A better solution may be using Wine's implementation. It requires internals
* (NtCreateKeyedEvent, NtReleaseKeyedEvent, and NtWaitForKeyedEvent) from
* ntdll, and implemention of exchange and compare-exchange for RefCounts.
*/
typedef struct {
RefCount wait_count;
HANDLE events[2];
} _int_alcnd_t;
enum {
SIGNAL = 0,
BROADCAST = 1
};
int alcnd_init(alcnd_t *cond)
{
_int_alcnd_t *icond = calloc(1, sizeof(*icond));
if(!icond) return althrd_nomem;
InitRef(&icond->wait_count, 0);
icond->events[SIGNAL] = CreateEvent(NULL, FALSE, FALSE, NULL);
icond->events[BROADCAST] = CreateEvent(NULL, TRUE, FALSE, NULL);
if(!icond->events[SIGNAL] || !icond->events[BROADCAST])
{
if(icond->events[SIGNAL])
CloseHandle(icond->events[SIGNAL]);
if(icond->events[BROADCAST])
CloseHandle(icond->events[BROADCAST]);
free(icond);
return althrd_error;
}
cond->Ptr = icond;
return althrd_success;
}
int alcnd_signal(alcnd_t *cond)
{
_int_alcnd_t *icond = cond->Ptr;
if(ReadRef(&icond->wait_count) > 0)
SetEvent(icond->events[SIGNAL]);
return althrd_success;
}
int alcnd_broadcast(alcnd_t *cond)
{
_int_alcnd_t *icond = cond->Ptr;
if(ReadRef(&icond->wait_count) > 0)
SetEvent(icond->events[BROADCAST]);
return althrd_success;
}
int alcnd_wait(alcnd_t *cond, almtx_t *mtx)
{
_int_alcnd_t *icond = cond->Ptr;
int res, last;
IncrementRef(&icond->wait_count);
LeaveCriticalSection(mtx);
res = WaitForMultipleObjects(2, icond->events, FALSE, INFINITE);
last = DecrementRef(&icond->wait_count) == 0 && res == WAIT_OBJECT_0+BROADCAST;
if(last) ResetEvent(icond->events[BROADCAST]);
EnterCriticalSection(mtx);
return althrd_success;
}
int alcnd_timedwait(alcnd_t *cond, almtx_t *mtx, const struct timespec *time_point)
{
_int_alcnd_t *icond = cond->Ptr;
struct timespec curtime;
DWORD sleeptime;
int res, last;
if(altimespec_get(&curtime, AL_TIME_UTC) != AL_TIME_UTC)
return althrd_error;
sleeptime = (time_point->tv_nsec - curtime.tv_nsec + 999999)/1000000;
sleeptime += (time_point->tv_sec - curtime.tv_sec)*1000;
IncrementRef(&icond->wait_count);
LeaveCriticalSection(mtx);
res = WaitForMultipleObjects(2, icond->events, FALSE, sleeptime);
last = DecrementRef(&icond->wait_count) == 0 && res == WAIT_OBJECT_0+BROADCAST;
if(last) ResetEvent(icond->events[BROADCAST]);
EnterCriticalSection(mtx);
return (res == WAIT_TIMEOUT) ? althrd_timedout : althrd_success;
}
void alcnd_destroy(alcnd_t *cond)
{
_int_alcnd_t *icond = cond->Ptr;
CloseHandle(icond->events[SIGNAL]);
CloseHandle(icond->events[BROADCAST]);
free(icond);
}
#endif /* defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x0600 */
/* An associative map of uint:void* pairs. The key is the TLS index (given by
* TlsAlloc), and the value is the altss_dtor_t callback. When a thread exits,

22
include/threads.h
View File

@ -39,6 +39,11 @@ struct timespec {
typedef DWORD althrd_t;
typedef CRITICAL_SECTION almtx_t;
#if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x0600
typedef CONDITION_VARIABLE alcnd_t;
#else
typedef struct { void *Ptr; } alcnd_t;
#endif
typedef DWORD altss_t;
typedef LONG alonce_flag;
@ -120,16 +125,6 @@ typedef pthread_once_t alonce_flag;
#define AL_ONCE_FLAG_INIT PTHREAD_ONCE_INIT
/* NOTE: Condition variables are POSIX-only at the moment, as Windows requires
* Vista or newer for them (without slow, hacky work-arounds). */
int alcnd_init(alcnd_t *cond);
int alcnd_signal(alcnd_t *cond);
int alcnd_broadcast(alcnd_t *cond);
int alcnd_wait(alcnd_t *cond, almtx_t *mtx);
int alcnd_timedwait(alcnd_t *cond, almtx_t *mtx, const struct timespec *time_point);
void alcnd_destroy(alcnd_t *cond);
inline althrd_t althrd_current(void)
{
return pthread_self();
@ -218,6 +213,13 @@ int almtx_init(almtx_t *mtx, int type);
void almtx_destroy(almtx_t *mtx);
int almtx_timedlock(almtx_t *mtx, const struct timespec *ts);
int alcnd_init(alcnd_t *cond);
int alcnd_signal(alcnd_t *cond);
int alcnd_broadcast(alcnd_t *cond);
int alcnd_wait(alcnd_t *cond, almtx_t *mtx);
int alcnd_timedwait(alcnd_t *cond, almtx_t *mtx, const struct timespec *time_point);
void alcnd_destroy(alcnd_t *cond);
int altss_create(altss_t *tss_id, altss_dtor_t callback);
void altss_delete(altss_t tss_id);