v/vlib/sync/sync_win.v

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// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
// 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 os
// Mutex HANDLE
type MHANDLE voidptr
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struct Mutex {
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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
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}
enum MutexState {
broken
waiting
released
abandoned
destroyed
}
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const (
INFINITE = 0xffffffff
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)
// Ref - https://docs.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-waitforsingleobject#return-value
const (
WAIT_ABANDONED = 0x00000080
WAIT_IO_COMPLETION = 0x000000C0
WAIT_OBJECT_0 = 0x00000000
WAIT_TIMEOUT = 0x00000102
WAIT_FAILED = 0xFFFFFFFF
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)
pub fn (m mut Mutex) lock() {
// if mutex handle not initalized
if isnil(m.mx) {
m.mx = 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, INFINITE) // infinite wait
m.state = match state {
WAIT_ABANDONED => { MutexState.abandoned }
WAIT_OBJECT_0 => { MutexState.waiting }
else => { MutexState.broken }
}
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}
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pub fn (m mut Mutex) unlock() {
if m.state == .waiting {
if C.ReleaseMutex(m.mx) != 0 {
m.state = .broken
return
}
}
m.state = .released
}
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pub fn (m mut 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
}