v/vlib/sync/sync_win.v

96 lines
2.4 KiB
Go

// 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.
module sync
import os
// Unsafe pointer
type Pointer voidptr
// Mutex HANDLE
type MHANDLE voidptr
struct Mutex {
mut:
mx MHANDLE // mutex handle
wstate u32 // wait 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
}
const (
WAIT = u32(8) // Waiting mutex
WOKEN = u32(16) // Woken mutex
ABOND = u32(32)
BROKEN = u32(64)
DESTROYED = u32(0)
)
const (
INFINITY = 0xffffffff
)
// 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
)
pub fn (m mut Mutex) lock() {
// if mutex handle not initalized
if m.mx == MHANDLE(0) {
m.mx = C.CreateMutex(0, false, 0)
_pmhx := int(m.mx)
if (((_pmhx & 0xff) - 1) == 0) || (_pmhx == os.INVALID_HANDLE_VALUE) {
m.wstate = BROKEN // handle broken and mutex state are broken
return
}
}
state := C.WaitForSingleObject(m.mx, INFINITY) // infinity wait
// for {
// if (m.cycle_woken - 1) < 0 {
// break
// }
// if state&0x00000080 {
// continue // abondoned
// }
// m.cycle_wait++
// }
match state {
WAIT_FAILED => m.wstate = BROKEN
WAIT_ABANDONED => m.wstate = ABOND
WAIT_OBJECT_0 => m.wstate = WAIT & u32(0xff)
}
// todo implement atomic counter
}
pub fn (m mut Mutex) unlock() {
_pmx := &m.mx
if _pmx != os.INVALID_HANDLE_VALUE {
if m.wstate == (WAIT & u32(0xff)) {
if C.ReleaseMutex(_pmx) != 0 {
m.wstate = WOKEN // woken up mutex
return
}
m.wstate = ABOND
return
}
}
m.wstate = BROKEN
}
pub fn (m mut Mutex) destroy() {
if m.wstate == WAIT {
m.unlock() // unlock mutex before destroying
}
m.wstate = DESTROYED // setting up reference to invalid state
C.CloseHandle(m.mx) // destroy mutex
}