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// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module sync
import time
#flag -lpthread
#include <semaphore.h>
#include <sys/errno.h>
[trusted]
fn C.pthread_mutex_init(voidptr, voidptr) int
fn C.pthread_mutex_lock(voidptr) int
fn C.pthread_mutex_unlock(voidptr) int
fn C.pthread_mutex_destroy(voidptr) int
fn C.pthread_rwlockattr_init(voidptr) int
fn C.pthread_rwlockattr_setkind_np(voidptr, int) int
fn C.pthread_rwlockattr_setpshared(voidptr, int) int
fn C.pthread_rwlock_init(voidptr, voidptr) int
fn C.pthread_rwlock_rdlock(voidptr) int
fn C.pthread_rwlock_wrlock(voidptr) int
fn C.pthread_rwlock_unlock(voidptr) int
fn C.pthread_condattr_init(voidptr) int
fn C.pthread_condattr_setpshared(voidptr, int) int
fn C.pthread_condattr_destroy(voidptr) int
fn C.pthread_cond_init(voidptr, voidptr) int
fn C.pthread_cond_signal(voidptr) int
fn C.pthread_cond_wait(voidptr, voidptr) int
fn C.pthread_cond_timedwait(voidptr, voidptr, voidptr) int
fn C.pthread_cond_destroy(voidptr) int
// [init_with=new_mutex] // TODO: implement support for this struct attribute, and disallow Mutex{} from outside the sync.new_mutex() function.
[heap]
pub struct Mutex {
mutex C.pthread_mutex_t
}
[heap]
pub struct RwMutex {
mutex C.pthread_rwlock_t
}
struct RwMutexAttr {
attr C.pthread_rwlockattr_t
}
struct CondAttr {
attr C.pthread_condattr_t
}
/*
MacOSX has no unnamed semaphores and no `timed_wait()` at all
so we emulate the behaviour with other devices
*/
[heap]
struct Semaphore {
mtx C.pthread_mutex_t
cond C.pthread_cond_t
mut:
count u32
}
pub fn new_mutex() &Mutex {
mut m := &Mutex{}
m.init()
return m
}
pub fn (mut m Mutex) init() {
C.pthread_mutex_init(&m.mutex, C.NULL)
}
pub fn new_rwmutex() &RwMutex {
mut m := &RwMutex{}
m.init()
return m
}
pub fn (mut m RwMutex) init() {
a := RwMutexAttr{}
C.pthread_rwlockattr_init(&a.attr)
// Give writer priority over readers
C.pthread_rwlockattr_setkind_np(&a.attr, C.PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP)
C.pthread_rwlockattr_setpshared(&a.attr, C.PTHREAD_PROCESS_PRIVATE)
C.pthread_rwlock_init(&m.mutex, &a.attr)
}
// @lock(), for *manual* mutex handling, since `lock` is a keyword
pub fn (mut m Mutex) @lock() {
C.pthread_mutex_lock(&m.mutex)
}
pub fn (mut m Mutex) unlock() {
C.pthread_mutex_unlock(&m.mutex)
}
// RwMutex has separate read- and write locks
pub fn (mut m RwMutex) @rlock() {
C.pthread_rwlock_rdlock(&m.mutex)
}
pub fn (mut m RwMutex) @lock() {
C.pthread_rwlock_wrlock(&m.mutex)
}
// Windows SRWLocks have different function to unlock
// So provide two functions here, too, to have a common interface
pub fn (mut m RwMutex) runlock() {
C.pthread_rwlock_unlock(&m.mutex)
}
pub fn (mut m RwMutex) unlock() {
C.pthread_rwlock_unlock(&m.mutex)
}
[inline]
pub fn new_semaphore() &Semaphore {
return new_semaphore_init(0)
}
pub fn new_semaphore_init(n u32) &Semaphore {
mut sem := &Semaphore{}
sem.init(n)
return sem
}
pub fn (mut sem Semaphore) init(n u32) {
C.atomic_store_u32(&sem.count, n)
C.pthread_mutex_init(&sem.mtx, C.NULL)
attr := CondAttr{}
C.pthread_condattr_init(&attr.attr)
C.pthread_condattr_setpshared(&attr.attr, C.PTHREAD_PROCESS_PRIVATE)
C.pthread_cond_init(&sem.cond, &attr.attr)
C.pthread_condattr_destroy(&attr.attr)
}
pub fn (mut sem Semaphore) post() {
mut c := C.atomic_load_u32(&sem.count)
for c > 1 {
if C.atomic_compare_exchange_weak_u32(&sem.count, &c, c + 1) {
return
}
}
C.pthread_mutex_lock(&sem.mtx)
c = C.atomic_fetch_add_u32(&sem.count, 1)
if c == 0 {
C.pthread_cond_signal(&sem.cond)
}
C.pthread_mutex_unlock(&sem.mtx)
}
pub fn (mut sem Semaphore) wait() {
mut c := C.atomic_load_u32(&sem.count)
for c > 0 {
if C.atomic_compare_exchange_weak_u32(&sem.count, &c, c - 1) {
return
}
}
C.pthread_mutex_lock(&sem.mtx)
c = C.atomic_load_u32(&sem.count)
outer: for {
if c == 0 {
C.pthread_cond_wait(&sem.cond, &sem.mtx)
c = C.atomic_load_u32(&sem.count)
}
for c > 0 {
if C.atomic_compare_exchange_weak_u32(&sem.count, &c, c - 1) {
if c > 1 {
C.pthread_cond_signal(&sem.cond)
}
break outer
}
}
}
C.pthread_mutex_unlock(&sem.mtx)
}
pub fn (mut sem Semaphore) try_wait() bool {
mut c := C.atomic_load_u32(&sem.count)
for c > 0 {
if C.atomic_compare_exchange_weak_u32(&sem.count, &c, c - 1) {
return true
}
}
return false
}
pub fn (mut sem Semaphore) timed_wait(timeout time.Duration) bool {
mut c := C.atomic_load_u32(&sem.count)
for c > 0 {
if C.atomic_compare_exchange_weak_u32(&sem.count, &c, c - 1) {
return true
}
}
C.pthread_mutex_lock(&sem.mtx)
t_spec := timeout.timespec()
mut res := 0
c = C.atomic_load_u32(&sem.count)
outer: for {
if c == 0 {
res = C.pthread_cond_timedwait(&sem.cond, &sem.mtx, &t_spec)
if res == C.ETIMEDOUT {
break outer
}
c = C.atomic_load_u32(&sem.count)
}
for c > 0 {
if C.atomic_compare_exchange_weak_u32(&sem.count, &c, c - 1) {
if c > 1 {
C.pthread_cond_signal(&sem.cond)
}
break outer
}
}
}
C.pthread_mutex_unlock(&sem.mtx)
return res == 0
}
pub fn (mut sem Semaphore) destroy() {
mut res := C.pthread_cond_destroy(&sem.cond)
if res == 0 {
res = C.pthread_mutex_destroy(&sem.mtx)
if res == 0 {
return
}
}
panic(unsafe { tos_clone(&byte(C.strerror(res))) })
}
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