v/vlib/sync/sync_windows.c.v

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// Copyright (c) 2019-2020 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
// TODO: The suggestion of using CriticalSection instead of mutex
// was discussed. Needs consideration.
// Mutex HANDLE
type MHANDLE voidptr
//[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 {
mut:
mx MHANDLE // mutex handle
state MutexState // mutex state
cycle_wait i64 // waiting cycles (implemented only with atomic)
cycle_woken i64 // woken cycles ^
reader_sem u32 // reader semarphone
writer_sem u32 // writer semaphones
}
[ref_only]
pub struct RwMutex {
mut:
mx C.SRWLOCK // mutex handle
}
enum MutexState {
broken
waiting
released
abandoned
destroyed
}
pub fn new_mutex() &Mutex {
sm := &Mutex{}
unsafe {
mut m := sm
m.mx = MHANDLE(C.CreateMutex(0, false, 0))
if isnil(m.mx) {
m.state = .broken // handle broken and mutex state are broken
return sm
}
}
return sm
}
pub fn new_rwmutex() &RwMutex {
m := &RwMutex{}
C.InitializeSRWLock(&m.mx)
return m
}
pub fn (mut m Mutex) m_lock() {
// if mutex handle not initalized
if isnil(m.mx) {
m.mx = MHANDLE(C.CreateMutex(0, false, 0))
if isnil(m.mx) {
m.state = .broken // handle broken and mutex state are broken
return
}
}
state := C.WaitForSingleObject(m.mx, C.INFINITE) // infinite wait
/* TODO fix match/enum combo
m.state = match state {
C.WAIT_ABANDONED { .abandoned }
C.WAIT_OBJECT_0 { .waiting }
else { .broken }
}
*/
if state == C.WAIT_ABANDONED {
m.state = .abandoned
// FIXME Use C constant instead
} else if state == 0 /* C.WAIT_OBJECT_0 */ {
m.state = .waiting
} else {
m.state = .broken
}
}
pub fn (mut m Mutex) unlock() {
if m.state == .waiting {
if C.ReleaseMutex(m.mx) {
m.state = .broken
return
}
}
m.state = .released
}
// RwMutex has separate read- and write locks
pub fn (mut m RwMutex) r_lock() {
C.AcquireSRWLockShared(&m.mx)
}
pub fn (mut m RwMutex) w_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) r_unlock() {
C.ReleaseSRWLockShared(&m.mx)
}
pub fn (mut m RwMutex) w_unlock() {
C.ReleaseSRWLockExclusive(&m.mx)
}
pub fn (mut m Mutex) destroy() {
if m.state == .waiting {
m.unlock() // unlock mutex before destroying
}
C.CloseHandle(m.mx) // destroy mutex
m.state = .destroyed // setting up reference to invalid state
}