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update rthreads.c from upstream

This commit is contained in:
zeromus 2017-09-17 04:02:14 -05:00
parent fda9fc2a89
commit c5cea732fa
1 changed files with 185 additions and 81 deletions
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266
desmume/src/libretro-common/rthreads/rthreads.c
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@ -37,6 +37,9 @@
#include <xtl.h>
#else
#define WIN32_LEAN_AND_MEAN
#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0500 /*_WIN32_WINNT_WIN2K */
#endif
#include <windows.h>
#include <mmsystem.h>
#endif
@ -52,7 +55,7 @@
#include <time.h>
#endif
#if defined(VITA)
#if defined(VITA) || defined(BSD)
#include <sys/time.h>
#endif
@ -97,10 +100,13 @@ struct QueueEntry
struct scond
{
#ifdef USE_WIN32_THREADS
/* With this implementation of scond, we don't have any way of waking (or even identifying) specific threads */
/* But we need to wake them in the order indicated by the queue. */
/* This potato token will get get passed around every waiter. The bearer can test whether he's next, and hold onto the potato if he is. */
/* When he's done he can then put it back into play to progress the queue further */
/* With this implementation of scond, we don't have any way of waking
* (or even identifying) specific threads
* But we need to wake them in the order indicated by the queue.
* This potato token will get get passed around every waiter.
* The bearer can test whether he's next, and hold onto the potato if he is.
* When he's done he can then put it back into play to progress
* the queue further */
HANDLE hot_potato;
/* The primary signalled event. Hot potatoes are passed until this is set. */
@ -112,7 +118,8 @@ struct scond
/* equivalent to the queue length */
int waiters;
/* how many waiters in the queue have been conceptually wakened by signals (even if we haven't managed to actually wake them yet) */
/* how many waiters in the queue have been conceptually wakened by signals
* (even if we haven't managed to actually wake them yet) */
int wakens;
/* used to control access to this scond, in case the user fails */
@ -152,7 +159,9 @@ sthread_t *sthread_create(void (*thread_func)(void*), void *userdata)
bool thread_created = false;
struct thread_data *data = NULL;
sthread_t *thread = (sthread_t*)calloc(1, sizeof(*thread));
#if defined(_WIN32_WINNT) && _WIN32_WINNT <= 0x0410
DWORD thread_id = 0;
#endif
if (!thread)
return NULL;
@ -164,7 +173,11 @@ sthread_t *sthread_create(void (*thread_func)(void*), void *userdata)
data->userdata = userdata;
#ifdef USE_WIN32_THREADS
thread->thread = CreateThread(NULL, 0, thread_wrap, data, 0, NULL);
#if defined(_WIN32_WINNT) && _WIN32_WINNT <= 0x0410
thread->thread = CreateThread(NULL, 0, thread_wrap, data, 0, &thread_id);
#else
thread->thread = CreateThread(NULL, 0, thread_wrap, data, 0, NULL);
#endif
thread_created = !!thread->thread;
#else
#if defined(VITA)
@ -224,6 +237,8 @@ int sthread_detach(sthread_t *thread)
*/
void sthread_join(sthread_t *thread)
{
if (!thread)
return;
#ifdef USE_WIN32_THREADS
WaitForSingleObject(thread->thread, INFINITE);
CloseHandle(thread->thread);
@ -356,16 +371,31 @@ scond_t *scond_new(void)
#ifdef USE_WIN32_THREADS
/* This is very complex because recreating condition variable semantics with win32 parts is not easy */
/* The main problem is that a condition variable can't be used to "pre-wake" a thread (it will get wakened only after it's waited) */
/* whereas a win32 event can pre-wake a thread (the event will be set in advance, so a 'waiter' won't even have to wait on it) */
/* Keep in mind a condition variable can apparently pre-wake a thread, insofar as spurious wakeups are always possible, */
/* but nobody will be expecting this and it does not need to be simulated. */
/* Moreover, we won't be doing this, because it counts as a spurious wakeup -- someone else with a genuine claim must get wakened, in any case. */
/* Therefore we choose to wake only one of the correct waiting threads. */
/* So at the very least, we need to do something clever. But there's bigger problems. */
/* We don't even have a straightforward way in win32 to satisfy pthread_cond_wait's atomicity requirement. The bulk of this algorithm is solving that. */
/* Note: We might could simplify this using vista+ condition variables, but we wanted an XP compatible solution. */
/* This is very complex because recreating condition variable semantics
* with Win32 parts is not easy.
*
* The main problem is that a condition variable can't be used to
* "pre-wake" a thread (it will get wakened only after it's waited).
*
* Whereas a win32 event can pre-wake a thread (the event will be set
* in advance, so a 'waiter' won't even have to wait on it).
*
* Keep in mind a condition variable can apparently pre-wake a thread,
* insofar as spurious wakeups are always possible,
* but nobody will be expecting this and it does not need to be simulated.
*
* Moreover, we won't be doing this, because it counts as a spurious wakeup
* -- someone else with a genuine claim must get wakened, in any case.
*
* Therefore we choose to wake only one of the correct waiting threads.
* So at the very least, we need to do something clever. But there's
* bigger problems.
* We don't even have a straightforward way in win32 to satisfy
* pthread_cond_wait's atomicity requirement. The bulk of this
* algorithm is solving that.
*
* Note: We might could simplify this using vista+ condition variables,
* but we wanted an XP compatible solution. */
cond->event = CreateEvent(NULL, FALSE, FALSE, NULL);
if (!cond->event) goto error;
cond->hot_potato = CreateEvent(NULL, FALSE, FALSE, NULL);
@ -380,7 +410,7 @@ scond_t *scond_new(void)
cond->head = NULL;
#else
if(pthread_cond_init(&cond->cond, NULL) != 0)
if (pthread_cond_init(&cond->cond, NULL) != 0)
goto error;
#endif
@ -415,68 +445,114 @@ void scond_free(scond_t *cond)
#ifdef USE_WIN32_THREADS
static bool _scond_wait_win32(scond_t *cond, slock_t *lock, DWORD dwMilliseconds)
{
static bool beginPeriod = false;
struct QueueEntry myentry;
struct QueueEntry **ptr;
#if _WIN32_WINNT >= 0x0500
static LARGE_INTEGER performanceCounterFrequency;
LARGE_INTEGER tsBegin;
static bool first_init = true;
#else
static bool beginPeriod = false;
DWORD tsBegin;
DWORD dwFinalTimeout = dwMilliseconds; /* Careful! in case we begin in the head, we don't do the hot potato stuff, so this timeout needs presetting */
#endif
DWORD waitResult;
DWORD dwFinalTimeout = dwMilliseconds; /* Careful! in case we begin in the head,
we don't do the hot potato stuff,
so this timeout needs presetting. */
/* Reminder: `lock` is held before this is called. */
/* however, someone else may have called scond_signal without the lock. soo... */
EnterCriticalSection(&cond->cs);
/* since this library is meant for realtime game software I have no problem setting this to 1 and forgetting about it. */
if(!beginPeriod)
/* since this library is meant for realtime game software
* I have no problem setting this to 1 and forgetting about it. */
#if _WIN32_WINNT >= 0x0500
if (first_init)
{
performanceCounterFrequency.QuadPart = 0;
first_init = false;
}
if (performanceCounterFrequency.QuadPart == 0)
{
QueryPerformanceFrequency(&performanceCounterFrequency);
}
#else
if (!beginPeriod)
{
beginPeriod = true;
timeBeginPeriod(1);
}
#endif
/* Now we can take a good timestamp for use in faking the timeout ourselves. */
/* But don't bother unless we need to (to save a little time) */
if(dwMilliseconds != INFINITE)
if (dwMilliseconds != INFINITE)
#if _WIN32_WINNT >= 0x0500
QueryPerformanceCounter(&tsBegin);
#else
tsBegin = timeGetTime();
#endif
/* add ourselves to a queue of waiting threads */
ptr = &cond->head;
while(*ptr) /* walk to the end of the linked list */
/* walk to the end of the linked list */
while (*ptr)
ptr = &((*ptr)->next);
*ptr = &myentry;
myentry.next = NULL;
cond->waiters++;
/* now the conceptual lock release and condition block are supposed to be atomic. */
/* we can't do that in windows, but we can simulate the effects by using the queue, by the following analysis: */
/* What happens if they aren't atomic? */
/* 1. a signaller can rush in and signal, expecting a waiter to get it; but the waiter wouldn't, because he isn't blocked yet */
/* solution: win32 events make this easy. the event will sit there enabled */
/* 2. a signaller can rush in and signal, and then turn right around and wait */
/* solution: the signaller will get queued behind the waiter, who's enqueued before he releases the mutex */
/* now the conceptual lock release and condition block are supposed to be atomic.
* we can't do that in Windows, but we can simulate the effects by using
* the queue, by the following analysis:
* What happens if they aren't atomic?
*
* 1. a signaller can rush in and signal, expecting a waiter to get it;
* but the waiter wouldn't, because he isn't blocked yet.
* Solution: Win32 events make this easy. The event will sit there enabled
*
* 2. a signaller can rush in and signal, and then turn right around and wait.
* Solution: the signaller will get queued behind the waiter, who's
* enqueued before he releases the mutex. */
/* It's my turn if I'm the head of the queue. Check to see if it's my turn. */
/* It's my turn if I'm the head of the queue.
* Check to see if it's my turn. */
while (cond->head != &myentry)
{
/* It isn't my turn: */
DWORD timeout = INFINITE;
/* As long as someone is even going to be able to wake up when they receive the potato, keep it going round */
/* As long as someone is even going to be able to wake up
* when they receive the potato, keep it going round. */
if (cond->wakens > 0)
SetEvent(cond->hot_potato);
/* Assess the remaining timeout time */
if(dwMilliseconds != INFINITE)
if (dwMilliseconds != INFINITE)
{
DWORD now = timeGetTime();
#if _WIN32_WINNT >= 0x0500
LARGE_INTEGER now;
LONGLONG elapsed;
QueryPerformanceCounter(&now);
elapsed = now.QuadPart - tsBegin.QuadPart;
elapsed *= 1000;
elapsed /= performanceCounterFrequency.QuadPart;
#else
DWORD now = timeGetTime();
DWORD elapsed = now - tsBegin;
if(elapsed > dwMilliseconds)
{
/* Try one last time with a zero timeout (keeps the code simpler) */
#endif
/* Try one last time with a zero timeout (keeps the code simpler) */
if (elapsed > dwMilliseconds)
elapsed = dwMilliseconds;
}
timeout = dwMilliseconds - elapsed;
}
@ -484,7 +560,8 @@ static bool _scond_wait_win32(scond_t *cond, slock_t *lock, DWORD dwMilliseconds
LeaveCriticalSection(&lock->lock);
LeaveCriticalSection(&cond->cs);
/* Wait a while to catch the hot potato.. someone else should get a chance to go */
/* Wait a while to catch the hot potato..
* someone else should get a chance to go */
/* After all, it isn't my turn (and it must be someone else's) */
Sleep(0);
waitResult = WaitForSingleObject(cond->hot_potato, timeout);
@ -493,23 +570,32 @@ static bool _scond_wait_win32(scond_t *cond, slock_t *lock, DWORD dwMilliseconds
EnterCriticalSection(&lock->lock);
EnterCriticalSection(&cond->cs);
if(waitResult == WAIT_TIMEOUT)
if (waitResult == WAIT_TIMEOUT)
{
/* Out of time! Now, let's think about this. I do have the potato now--maybe it's my turn, and I have the event? */
/* If that's the case, I could proceed right now without aborting due to timeout. */
/* However.. I DID wait a real long time. The caller was willing to wait that long. */
/* I choose to give him one last chance with a zero timeout in the next step */
if(cond->head == &myentry)
/* Out of time! Now, let's think about this. I do have the potato now--
* maybe it's my turn, and I have the event?
* If that's the case, I could proceed right now without aborting
* due to timeout.
*
* However.. I DID wait a real long time. The caller was willing
* to wait that long.
*
* I choose to give him one last chance with a zero timeout
* in the next step
*/
if (cond->head == &myentry)
{
dwFinalTimeout = 0;
break;
}
else
{
/* It's not our turn and we're out of time. Give up. */
/* Remove ourself from the queue and bail. */
/* It's not our turn and we're out of time. Give up.
* Remove ourself from the queue and bail. */
struct QueueEntry* curr = cond->head;
while(curr->next != &myentry) curr = curr->next;
while (curr->next != &myentry)
curr = curr->next;
curr->next = myentry.next;
cond->waiters--;
LeaveCriticalSection(&cond->cs);
@ -527,10 +613,12 @@ static bool _scond_wait_win32(scond_t *cond, slock_t *lock, DWORD dwMilliseconds
LeaveCriticalSection(&cond->cs);
/* Wait for someone to actually signal this condition */
/* We're the only waiter waiting on the event right now -- everyone else is waiting on something different */
/* We're the only waiter waiting on the event right now -- everyone else
* is waiting on something different */
waitResult = WaitForSingleObject(cond->event, dwFinalTimeout);
/* Take the main lock so we can do work. Nobody else waits on this lock for very long, so even though it's GO TIME we won't have to wait long */
/* Take the main lock so we can do work. Nobody else waits on this lock
* for very long, so even though it's GO TIME we won't have to wait long */
EnterCriticalSection(&lock->lock);
EnterCriticalSection(&cond->cs);
@ -538,7 +626,7 @@ static bool _scond_wait_win32(scond_t *cond, slock_t *lock, DWORD dwMilliseconds
cond->head = myentry.next;
cond->waiters--;
if(waitResult == WAIT_TIMEOUT)
if (waitResult == WAIT_TIMEOUT)
{
/* Oops! ran out of time in the final wait. Just bail. */
LeaveCriticalSection(&cond->cs);
@ -546,13 +634,15 @@ static bool _scond_wait_win32(scond_t *cond, slock_t *lock, DWORD dwMilliseconds
}
/* If any other wakenings are pending, go ahead and set it up */
/* There may actually be no waiters. That's OK. The first waiter will come in, find it's his turn, and immediately get the signaled event */
/* There may actually be no waiters. That's OK. The first waiter will come in,
* find it's his turn, and immediately get the signaled event */
cond->wakens--;
if (cond->wakens > 0)
{
SetEvent(cond->event);
/* Progress the queue: Put the hot potato back into play. It'll be tossed around until next in line gets it */
/* Progress the queue: Put the hot potato back into play. It'll be
* tossed around until next in line gets it */
SetEvent(cond->hot_potato);
}
@ -587,12 +677,13 @@ void scond_wait(scond_t *cond, slock_t *lock)
int scond_broadcast(scond_t *cond)
{
#ifdef USE_WIN32_THREADS
/* remember: we currently have mutex */
if(cond->waiters == 0) return 0;
if (cond->waiters == 0)
return 0;
/* awaken everything which is currently queued up */
if(cond->wakens == 0) SetEvent(cond->event);
if (cond->wakens == 0)
SetEvent(cond->event);
cond->wakens = cond->waiters;
/* Since there is now at least one pending waken, the potato must be in play */
@ -615,27 +706,31 @@ void scond_signal(scond_t *cond)
{
#ifdef USE_WIN32_THREADS
/* Unfortunately, pthread_cond_signal does not require that the lock be held in advance */
/* To avoid stomping on the condvar from other threads, we need to control access to it with this */
/* Unfortunately, pthread_cond_signal does not require that the
* lock be held in advance */
/* To avoid stomping on the condvar from other threads, we need
* to control access to it with this */
EnterCriticalSection(&cond->cs);
/* remember: we currently have mutex */
if(cond->waiters == 0)
if (cond->waiters == 0)
{
LeaveCriticalSection(&cond->cs);
return;
}
/* wake up the next thing in the queue */
if(cond->wakens == 0) SetEvent(cond->event);
if (cond->wakens == 0)
SetEvent(cond->event);
cond->wakens++;
/* The data structure is done being modified.. I think we can leave the CS now. */
/* This would prevent some other thread from receiving the hot potato and then
/* immediately stalling for the critical section. */
/* But remember, we were trying to replicate a semantic where this entire scond_signal call
/* was controlled (by the user) by a lock. */
/* So in case there's trouble with this, we can move it after SetEvent() */
/* The data structure is done being modified.. I think we can leave the CS now.
* This would prevent some other thread from receiving the hot potato and then
* immediately stalling for the critical section.
* But remember, we were trying to replicate a semantic where this entire
* scond_signal call was controlled (by the user) by a lock.
* So in case there's trouble with this, we can move it after SetEvent() */
LeaveCriticalSection(&cond->cs);
/* Since there is now at least one pending waken, the potato must be in play */
@ -661,19 +756,28 @@ void scond_signal(scond_t *cond)
bool scond_wait_timeout(scond_t *cond, slock_t *lock, int64_t timeout_us)
{
#ifdef USE_WIN32_THREADS
/* How to convert a us timeout to ms? */
/* Someone asking for a 0 timeout clearly wants immediate timeout. */
/* Someone asking for a 1 timeout clearly wants an actual timeout of the minimum length */
/* Someone asking for 1000 or 1001 timeout shouldn't accidentally get 2ms. */
/* How to convert a microsecond (us) timeout to millisecond (ms)?
*
* Someone asking for a 0 timeout clearly wants immediate timeout.
* Someone asking for a 1 timeout clearly wants an actual timeout
* of the minimum length */
/* Someone asking for 1000 or 1001 timeout shouldn't
* accidentally get 2ms. */
DWORD dwMilliseconds = timeout_us/1000;
if(timeout_us == 0) {
/* The implementation of a 0 timeout here with pthreads is sketchy. */
/* It isn't clear what happens if pthread_cond_timedwait is called with NOW. */
/* Moreover, it is possible that this thread gets pre-empted after the clock_gettime but before the pthread_cond_timedwait. */
/* In order to help smoke out problems caused by this strange usage, let's treat a 0 timeout as always timing out. */
/* The implementation of a 0 timeout here with pthreads is sketchy.
* It isn't clear what happens if pthread_cond_timedwait is called with NOW.
* Moreover, it is possible that this thread gets pre-empted after the
* clock_gettime but before the pthread_cond_timedwait.
* In order to help smoke out problems caused by this strange usage,
* let's treat a 0 timeout as always timing out.
*/
if (timeout_us == 0)
return false;
}
else if(timeout_us < 1000) dwMilliseconds = 1;
else if (timeout_us < 1000)
dwMilliseconds = 1;
return _scond_wait_win32(cond,lock,dwMilliseconds);
#else
int ret;