96 lines
2.4 KiB
Go
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
|
|
}
|