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v/vlib/sync/sync_nix.c.v

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// Copyright (c) 2019-2020 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
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module sync
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import time
#flag -lpthread
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#include <semaphore.h>
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// [init_with=new_mutex] // TODO: implement support for this struct attribute, and disallow Mutex{} from outside the sync.new_mutex() function.
[ref_only]
pub struct Mutex {
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mutex C.pthread_mutex_t
}
[ref_only]
pub struct RwMutex {
mutex C.pthread_rwlock_t
}
[ref_only]
struct RwMutexAttr {
attr C.pthread_rwlockattr_t
}
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/* MacOSX has no unnamed semaphores and no `timed_wait()` at all
so we emulate the behaviour with other devices */
struct MacOSX_Semaphore {
mtx C.pthread_mutex_t
cond C.pthread_cond_t
mut:
count int
}
[ref_only]
struct PosixSemaphore {
sem C.sem_t
}
[ref_only]
struct CondAttr {
attr C.pthread_condattr_t
}
pub struct Semaphore {
/*
$if macos {
sem &MacOSX_Semaphore
} $else {
sem &PosixSemaphore
}
*/
sem voidptr // since the above does not work, yet
}
pub fn new_mutex() &Mutex {
m := &Mutex{}
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C.pthread_mutex_init(&m.mutex, C.NULL)
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return m
}
pub fn new_rwmutex() &RwMutex {
m := &RwMutex{}
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)
return m
}
// m_lock(), for *manual* mutex handling, since `lock` is a keyword
pub fn (mut m Mutex) m_lock() {
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C.pthread_mutex_lock(&m.mutex)
}
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pub fn (mut m Mutex) unlock() {
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C.pthread_mutex_unlock(&m.mutex)
}
// RwMutex has separate read- and write locks
pub fn (mut m RwMutex) r_lock() {
C.pthread_rwlock_rdlock(&m.mutex)
}
pub fn (mut m RwMutex) w_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) r_unlock() {
C.pthread_rwlock_unlock(&m.mutex)
}
pub fn (mut m RwMutex) w_unlock() {
C.pthread_rwlock_unlock(&m.mutex)
}
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pub fn new_semaphore() Semaphore {
$if macos {
s := Semaphore{
sem: &MacOSX_Semaphore{count: 0}
}
C.pthread_mutex_init(&&MacOSX_Semaphore(s.sem).mtx, C.NULL)
a := &CondAttr{}
C.pthread_condattr_init(&a.attr)
C.pthread_condattr_setpshared(&a.attr, C.PTHREAD_PROCESS_PRIVATE)
C.pthread_cond_init(&&MacOSX_Semaphore(s.sem).cond, &a.attr)
return s
} $else {
s := Semaphore{
sem: &PosixSemaphore{}
}
C.sem_init(&&PosixSemaphore(s.sem).sem, 0, 0)
return s
}
}
pub fn (s Semaphore) post() {
$if macos {
C.pthread_mutex_lock(&&MacOSX_Semaphore(s.sem).mtx)
(&MacOSX_Semaphore(s.sem)).count++
C.pthread_cond_signal(&&MacOSX_Semaphore(s.sem).cond)
C.pthread_mutex_unlock(&&MacOSX_Semaphore(s.sem).mtx)
} $else {
C.sem_post(&&PosixSemaphore(s.sem).sem)
}
}
pub fn (s Semaphore) wait() {
$if macos {
C.pthread_mutex_lock(&&MacOSX_Semaphore(s.sem).mtx)
for &MacOSX_Semaphore(s.sem).count == 0 {
C.pthread_cond_wait(&&MacOSX_Semaphore(s.sem).cond, &&MacOSX_Semaphore(s.sem).mtx)
}
(&MacOSX_Semaphore(s.sem)).count--
C.pthread_mutex_unlock(&&MacOSX_Semaphore(s.sem).mtx)
} $else {
C.sem_wait(&&PosixSemaphore(s.sem).sem)
}
}
pub fn (s Semaphore) try_wait() bool {
$if macos {
t_spec := time.zero_timespec()
C.pthread_mutex_lock(&&MacOSX_Semaphore(s.sem).mtx)
for &MacOSX_Semaphore(s.sem).count == 0 {
res := C.pthread_cond_timedwait(&&MacOSX_Semaphore(s.sem).cond, &&MacOSX_Semaphore(s.sem).mtx, &t_spec)
if res == C.ETIMEDOUT {
break
}
}
mut res := false
if &MacOSX_Semaphore(s.sem).count > 0 { // success
(&MacOSX_Semaphore(s.sem)).count--
res = true
}
C.pthread_mutex_unlock(&&MacOSX_Semaphore(s.sem).mtx)
return res
} $else {
return C.sem_trywait(&&PosixSemaphore(s.sem).sem) == 0
}
}
pub fn (s Semaphore) timed_wait(timeout time.Duration) bool {
t_spec := timeout.timespec()
$if macos {
C.pthread_mutex_lock(&&MacOSX_Semaphore(s.sem).mtx)
for &MacOSX_Semaphore(s.sem).count == 0 {
res := C.pthread_cond_timedwait(&&MacOSX_Semaphore(s.sem).cond, &&MacOSX_Semaphore(s.sem).mtx, &t_spec)
if res == C.ETIMEDOUT {
break
}
}
mut res := false
if &MacOSX_Semaphore(s.sem).count > 0 { // success
(&MacOSX_Semaphore(s.sem)).count--
res = true
}
C.pthread_mutex_unlock(&&MacOSX_Semaphore(s.sem).mtx)
return res
} $else {
return C.sem_timedwait(&&PosixSemaphore(s.sem).sem, &t_spec) == 0
}
}