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v/vlib/sync/sync_windows.c.v

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V

// 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
#include <synchapi.h>
fn C.InitializeConditionVariable(voidptr)
fn C.WakeConditionVariable(voidptr)
fn C.SleepConditionVariableSRW(voidptr, voidptr, u32, u32) int
// TODO: The suggestion of using CriticalSection instead of mutex
// was discussed. Needs consideration.
// Mutex HANDLE
type MHANDLE = voidptr
// Semaphore HANDLE
type SHANDLE = voidptr
//[init_with=new_mutex] // TODO: implement support for this struct attribute, and disallow Mutex{} from outside the sync.new_mutex() function.
// `SRWLOCK` is much more performant that `Mutex` on Windows, so use that in both cases since we don't want to share with other processes
pub struct Mutex {
mut:
mx C.SRWLOCK // mutex handle
}
pub struct RwMutex {
mut:
mx C.SRWLOCK // mutex handle
}
struct Semaphore {
mtx C.SRWLOCK
cond C.CONDITION_VARIABLE
mut:
count u32
}
pub fn new_mutex() &Mutex {
mut m := &Mutex{}
m.init()
return m
}
pub fn new_rwmutex() &RwMutex {
mut m := &RwMutex{}
m.init()
return m
}
pub fn (mut m Mutex) init() {
C.InitializeSRWLock(&m.mx)
}
pub fn (mut m RwMutex) init() {
C.InitializeSRWLock(&m.mx)
}
pub fn (mut m Mutex) @lock() {
C.AcquireSRWLockExclusive(&m.mx)
}
pub fn (mut m Mutex) unlock() {
C.ReleaseSRWLockExclusive(&m.mx)
}
// RwMutex has separate read- and write locks
pub fn (mut m RwMutex) @rlock() {
C.AcquireSRWLockShared(&m.mx)
}
pub fn (mut m RwMutex) @lock() {
C.AcquireSRWLockExclusive(&m.mx)
}
// 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.ReleaseSRWLockShared(&m.mx)
}
pub fn (mut m RwMutex) unlock() {
C.ReleaseSRWLockExclusive(&m.mx)
}
pub fn (mut m Mutex) destroy() {
// nothing to do
}
[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.InitializeSRWLock(&sem.mtx)
C.InitializeConditionVariable(&sem.cond)
}
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.AcquireSRWLockExclusive(&sem.mtx)
c = C.atomic_fetch_add_u32(&sem.count, 1)
if c == 0 {
C.WakeConditionVariable(&sem.cond)
}
C.ReleaseSRWLockExclusive(&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.AcquireSRWLockExclusive(&sem.mtx)
c = C.atomic_load_u32(&sem.count)
outer:
for {
if c == 0 {
C.SleepConditionVariableSRW(&sem.cond, &sem.mtx, C.INFINITE, 0)
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.WakeConditionVariable(&sem.cond)
}
break outer
}
}
}
C.ReleaseSRWLockExclusive(&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.AcquireSRWLockExclusive(&sem.mtx)
t_ms := u32(timeout / time.millisecond)
mut res := 0
c = C.atomic_load_u32(&sem.count)
outer:
for {
if c == 0 {
res = C.SleepConditionVariableSRW(&sem.cond, &sem.mtx, t_ms, 0)
if res == 0 {
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.WakeConditionVariable(&sem.cond)
}
break outer
}
}
}
C.ReleaseSRWLockExclusive(&sem.mtx)
return res != 0
}
pub fn (s Semaphore) destroy() bool {
return true
}