mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-10-06 15:11:58 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 10

bpo-12822: use monotonic clock for condvar if possible (GH-11723)

Browse source
This commit is contained in:
Inada Naoki 2019-02-20 10:00:09 +09:00 • committed by GitHub
parent 46a97920fe
commit 001fee14e0
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
8 changed files with 87 additions and 51 deletions
Download patch file Download diff file Expand all files Collapse all files

81
Python/thread_pthread.h
View file

@ -56,16 +56,6 @@
#endif
#endif
#if !defined(pthread_attr_default)
# define pthread_attr_default ((pthread_attr_t *)NULL)
#endif
#if !defined(pthread_mutexattr_default)
# define pthread_mutexattr_default ((pthread_mutexattr_t *)NULL)
#endif
#if !defined(pthread_condattr_default)
# define pthread_condattr_default ((pthread_condattr_t *)NULL)
#endif
/* Whether or not to use semaphores directly rather than emulating them with
* mutexes and condition variables:
@ -110,6 +100,56 @@ do { \
} while(0)
/*
* pthread_cond support
*/
#if defined(HAVE_PTHREAD_CONDATTR_SETCLOCK) && defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
// monotonic is supported statically. It doesn't mean it works on runtime.
#define CONDATTR_MONOTONIC
#endif
// NULL when pthread_condattr_setclock(CLOCK_MONOTONIC) is not supported.
static pthread_condattr_t *condattr_monotonic = NULL;
static void
init_condattr()
{
#ifdef CONDATTR_MONOTONIC
static pthread_condattr_t ca;
pthread_condattr_init(&ca);
if (pthread_condattr_setclock(&ca, CLOCK_MONOTONIC) == 0) {
condattr_monotonic = &ca; // Use monotonic clock
}
#endif
}
int
_PyThread_cond_init(PyCOND_T *cond)
{
return pthread_cond_init(cond, condattr_monotonic);
}
void
_PyThread_cond_after(long long us, struct timespec *abs)
{
#ifdef CONDATTR_MONOTONIC
if (condattr_monotonic) {
clock_gettime(CLOCK_MONOTONIC, abs);
abs->tv_sec += us / 1000000;
abs->tv_nsec += (us % 1000000) * 1000;
abs->tv_sec += abs->tv_nsec / 1000000000;
abs->tv_nsec %= 1000000000;
return;
}
#endif
struct timespec ts;
MICROSECONDS_TO_TIMESPEC(us, ts);
*abs = ts;
}
/* A pthread mutex isn't sufficient to model the Python lock type
* because, according to Draft 5 of the docs (P1003.4a/D5), both of the
* following are undefined:
@ -146,6 +186,7 @@ PyThread__init_thread(void)
extern void pthread_init(void);
pthread_init();
#endif
init_condattr();
}
/*
@ -462,8 +503,7 @@ PyThread_allocate_lock(void)
memset((void *)lock, '\0', sizeof(pthread_lock));
lock->locked = 0;
status = pthread_mutex_init(&lock->mut,
pthread_mutexattr_default);
status = pthread_mutex_init(&lock->mut, NULL);
CHECK_STATUS_PTHREAD("pthread_mutex_init");
/* Mark the pthread mutex underlying a Python mutex as
pure happens-before. We can't simply mark the
@ -472,8 +512,7 @@ PyThread_allocate_lock(void)
will cause errors. */
_Py_ANNOTATE_PURE_HAPPENS_BEFORE_MUTEX(&lock->mut);
status = pthread_cond_init(&lock->lock_released,
pthread_condattr_default);
status = _PyThread_cond_init(&lock->lock_released);
CHECK_STATUS_PTHREAD("pthread_cond_init");
if (error) {
@ -532,9 +571,10 @@ PyThread_acquire_lock_timed(PyThread_type_lock lock, PY_TIMEOUT_T microseconds,
success = PY_LOCK_ACQUIRED;
}
else if (microseconds != 0) {
struct timespec ts;
if (microseconds > 0)
MICROSECONDS_TO_TIMESPEC(microseconds, ts);
struct timespec abs;
if (microseconds > 0) {
_PyThread_cond_after(microseconds, &abs);
}
/* continue trying until we get the lock */
/* mut must be locked by me -- part of the condition
@ -543,10 +583,13 @@ PyThread_acquire_lock_timed(PyThread_type_lock lock, PY_TIMEOUT_T microseconds,
if (microseconds > 0) {
status = pthread_cond_timedwait(
&thelock->lock_released,
&thelock->mut, &ts);
&thelock->mut, &abs);
if (status == 1) {
break;
}
if (status == ETIMEDOUT)
break;
CHECK_STATUS_PTHREAD("pthread_cond_timed_wait");
CHECK_STATUS_PTHREAD("pthread_cond_timedwait");
}
else {
status = pthread_cond_wait(