89 lines
2.0 KiB
V
89 lines
2.0 KiB
V
// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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module sync
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// Mutex HANDLE
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type MHANDLE voidptr
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//[init_with=new_mutex] // TODO: implement support for this struct attribute, and disallow Mutex{} from outside the sync.new_mutex() function.
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pub struct Mutex {
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mut:
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mx MHANDLE // mutex handle
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state MutexState // mutex state
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cycle_wait i64 // waiting cycles (implemented only with atomic)
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cycle_woken i64 // woken cycles ^
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reader_sem u32 // reader semarphone
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writer_sem u32 // writer semaphones
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}
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enum MutexState {
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broken
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waiting
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released
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abandoned
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destroyed
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}
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const (
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INFINITE = 0xffffffff
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)
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// Ref - https://docs.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-waitforsingleobject#return-value
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const (
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WAIT_ABANDONED = 0x00000080
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WAIT_IO_COMPLETION = 0x000000C0
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WAIT_OBJECT_0 = 0x00000000
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WAIT_TIMEOUT = 0x00000102
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WAIT_FAILED = 0xFFFFFFFF
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)
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pub fn new_mutex() Mutex {
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sm := Mutex{}
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unsafe {
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mut m := sm
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m.mx = C.CreateMutex(0, false, 0)
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if isnil(m.mx) {
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m.state = .broken // handle broken and mutex state are broken
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return sm
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}
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return sm
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}
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}
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pub fn (m mut Mutex) lock() {
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// if mutex handle not initalized
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if isnil(m.mx) {
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m.mx = C.CreateMutex(0, false, 0)
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if isnil(m.mx) {
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m.state = .broken // handle broken and mutex state are broken
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return
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}
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}
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state := C.WaitForSingleObject(m.mx, INFINITE) // infinite wait
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m.state = match state {
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WAIT_ABANDONED { .abandoned }
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WAIT_OBJECT_0 { .waiting }
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else { .broken }
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}
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}
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pub fn (m mut Mutex) unlock() {
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if m.state == .waiting {
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if C.ReleaseMutex(m.mx) != 0 {
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m.state = .broken
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return
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}
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}
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m.state = .released
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}
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pub fn (m mut Mutex) destroy() {
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if m.state == .waiting {
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m.unlock() // unlock mutex before destroying
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}
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C.CloseHandle(m.mx) // destroy mutex
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m.state = .destroyed // setting up reference to invalid state
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}
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