mirrors/cosmopolitan
1
0
Fork 0
mirror of https://github.com/jart/cosmopolitan.git synced 2025-06-28 07:18:30 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 1

Make more improvements to threads and mappings

Browse source 
- NetBSD should now have faster synchronization
- POSIX barriers may now be shared across processes
- An edge case with memory map tracking has been fixed
- Grand Central Dispatch is no longer used on MacOS ARM64
- POSIX mutexes in normal mode now use futexes across processes
This commit is contained in:
Justine Tunney 2024-07-24 01:05:00 -07:00
parent 2187d6d2dd
commit e398f3887c
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
20 changed files with 566 additions and 171 deletions
Download patch file Download diff file Expand all files Collapse all files

90
libc/intrin/pthread_mutex_unlock.c
View file

@ -25,45 +25,26 @@
#include "libc/runtime/internal.h"
#include "libc/thread/lock.h"
#include "libc/thread/thread.h"
#include "third_party/nsync/futex.internal.h"
#include "third_party/nsync/mu.h"
/**
* Releases mutex.
*
* This function does nothing in vfork() children.
*
* @return 0 on success or error number on failure
* @raises EPERM if in error check mode and not owned by caller
* @vforksafe
*/
errno_t pthread_mutex_unlock(pthread_mutex_t *mutex) {
int me;
uint64_t word, lock;
static void pthread_mutex_unlock_naive(pthread_mutex_t *mutex, uint64_t word) {
uint64_t lock = MUTEX_UNLOCK(word);
atomic_store_explicit(&mutex->_word, lock, memory_order_release);
}
LOCKTRACE("pthread_mutex_unlock(%t)", mutex);
// get current state of lock
word = atomic_load_explicit(&mutex->_word, memory_order_relaxed);
#if PTHREAD_USE_NSYNC
// use fancy nsync mutex if possible
if (MUTEX_TYPE(word) == PTHREAD_MUTEX_NORMAL && //
MUTEX_PSHARED(word) == PTHREAD_PROCESS_PRIVATE && //
_weaken(nsync_mu_unlock)) {
_weaken(nsync_mu_unlock)((nsync_mu *)mutex);
return 0;
// see "take 3" algorithm in "futexes are tricky" by ulrich drepper
static void pthread_mutex_unlock_drepper(atomic_int *futex, char pshare) {
int word = atomic_fetch_sub_explicit(futex, 1, memory_order_release);
if (word == 2) {
atomic_store_explicit(futex, 0, memory_order_release);
_weaken(nsync_futex_wake_)(futex, 1, pshare);
}
#endif
}
// implement barebones normal mutexes
if (MUTEX_TYPE(word) == PTHREAD_MUTEX_NORMAL) {
lock = MUTEX_UNLOCK(word);
atomic_store_explicit(&mutex->_word, lock, memory_order_release);
return 0;
}
// implement recursive mutex unlocking
me = gettid();
static errno_t pthread_mutex_unlock_recursive(pthread_mutex_t *mutex,
uint64_t word) {
int me = gettid();
for (;;) {
// we allow unlocking an initialized lock that wasn't locked, but we
@ -88,3 +69,44 @@ errno_t pthread_mutex_unlock(pthread_mutex_t *mutex) {
return 0;
}
}
/**
* Releases mutex.
*
* This function does nothing in vfork() children.
*
* @return 0 on success or error number on failure
* @raises EPERM if in error check mode and not owned by caller
* @vforksafe
*/
errno_t pthread_mutex_unlock(pthread_mutex_t *mutex) {
uint64_t word;
LOCKTRACE("pthread_mutex_unlock(%t)", mutex);
// get current state of lock
word = atomic_load_explicit(&mutex->_word, memory_order_relaxed);
#if PTHREAD_USE_NSYNC
// use superior mutexes if possible
if (MUTEX_TYPE(word) == PTHREAD_MUTEX_NORMAL && //
MUTEX_PSHARED(word) == PTHREAD_PROCESS_PRIVATE && //
_weaken(nsync_mu_unlock)) {
_weaken(nsync_mu_unlock)((nsync_mu *)mutex);
return 0;
}
#endif
// implement barebones normal mutexes
if (MUTEX_TYPE(word) == PTHREAD_MUTEX_NORMAL) {
if (_weaken(nsync_futex_wake_)) {
pthread_mutex_unlock_drepper(&mutex->_futex, MUTEX_PSHARED(word));
} else {
pthread_mutex_unlock_naive(mutex, word);
}
return 0;
}
// handle recursive and error checking mutexes
return pthread_mutex_unlock_recursive(mutex, word);
}