1 files changed, 212 insertions, 0 deletions
diff --git a/v_windows/v/vlib/sync/sync_windows.c.v b/v_windows/v/vlib/sync/sync_windows.c.v
new file mode 100644
index 0000000..d0942b7
--- /dev/null
+++ b/v_windows/v/vlib/sync/sync_windows.c.v
@@ -0,0 +1,212 @@
+// Copyright (c) 2019-2021 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 time
+
+#include <synchapi.h>
+#include <time.h>
+
+fn C.GetSystemTimeAsFileTime(lpSystemTimeAsFileTime &C._FILETIME)
+fn C.InitializeConditionVariable(voidptr)
+fn C.WakeConditionVariable(voidptr)
+fn C.SleepConditionVariableSRW(voidptr, voidptr, u32, u32) int
+
+// TODO: The suggestion of using CriticalSection instead of mutex
+// was discussed. Needs consideration.
+
+// Mutex HANDLE
+type MHANDLE = voidptr
+
+// Semaphore HANDLE
+type SHANDLE = voidptr
+
+//[init_with=new_mutex] // TODO: implement support for this struct attribute, and disallow Mutex{} from outside the sync.new_mutex() function.
+
+// `SRWLOCK` is much more performant that `Mutex` on Windows, so use that in both cases since we don't want to share with other processes
+[heap]
+pub struct Mutex {
+mut:
+	mx C.SRWLOCK // mutex handle
+}
+
+[heap]
+pub struct RwMutex {
+mut:
+	mx C.SRWLOCK // mutex handle
+}
+
+[heap]
+struct Semaphore {
+	mtx  C.SRWLOCK
+	cond C.CONDITION_VARIABLE
+mut:
+	count u32
+}
+
+pub fn new_mutex() &Mutex {
+	mut m := &Mutex{}
+	m.init()
+	return m
+}
+
+pub fn new_rwmutex() &RwMutex {
+	mut m := &RwMutex{}
+	m.init()
+	return m
+}
+
+pub fn (mut m Mutex) init() {
+	C.InitializeSRWLock(&m.mx)
+}
+
+pub fn (mut m RwMutex) init() {
+	C.InitializeSRWLock(&m.mx)
+}
+
+pub fn (mut m Mutex) @lock() {
+	C.AcquireSRWLockExclusive(&m.mx)
+}
+
+pub fn (mut m Mutex) unlock() {
+	C.ReleaseSRWLockExclusive(&m.mx)
+}
+
+// RwMutex has separate read- and write locks
+pub fn (mut m RwMutex) @rlock() {
+	C.AcquireSRWLockShared(&m.mx)
+}
+
+pub fn (mut m RwMutex) @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) runlock() {
+	C.ReleaseSRWLockShared(&m.mx)
+}
+
+pub fn (mut m RwMutex) unlock() {
+	C.ReleaseSRWLockExclusive(&m.mx)
+}
+
+pub fn (mut m Mutex) destroy() {
+	// nothing to do
+}
+
+[inline]
+pub fn new_semaphore() &Semaphore {
+	return new_semaphore_init(0)
+}
+
+pub fn new_semaphore_init(n u32) &Semaphore {
+	mut sem := &Semaphore{}
+	sem.init(n)
+	return sem
+}
+
+pub fn (mut sem Semaphore) init(n u32) {
+	C.atomic_store_u32(&sem.count, n)
+	C.InitializeSRWLock(&sem.mtx)
+	C.InitializeConditionVariable(&sem.cond)
+}
+
+pub fn (mut sem Semaphore) post() {
+	mut c := C.atomic_load_u32(&sem.count)
+	for c > 1 {
+		if C.atomic_compare_exchange_weak_u32(&sem.count, &c, c + 1) {
+			return
+		}
+	}
+	C.AcquireSRWLockExclusive(&sem.mtx)
+	c = C.atomic_fetch_add_u32(&sem.count, 1)
+	if c == 0 {
+		C.WakeConditionVariable(&sem.cond)
+	}
+	C.ReleaseSRWLockExclusive(&sem.mtx)
+}
+
+pub fn (mut sem Semaphore) wait() {
+	mut c := C.atomic_load_u32(&sem.count)
+	for c > 0 {
+		if C.atomic_compare_exchange_weak_u32(&sem.count, &c, c - 1) {
+			return
+		}
+	}
+	C.AcquireSRWLockExclusive(&sem.mtx)
+	c = C.atomic_load_u32(&sem.count)
+
+	outer: for {
+		if c == 0 {
+			C.SleepConditionVariableSRW(&sem.cond, &sem.mtx, C.INFINITE, 0)
+			c = C.atomic_load_u32(&sem.count)
+		}
+		for c > 0 {
+			if C.atomic_compare_exchange_weak_u32(&sem.count, &c, c - 1) {
+				if c > 1 {
+					C.WakeConditionVariable(&sem.cond)
+				}
+				break outer
+			}
+		}
+	}
+	C.ReleaseSRWLockExclusive(&sem.mtx)
+}
+
+pub fn (mut sem Semaphore) try_wait() bool {
+	mut c := C.atomic_load_u32(&sem.count)
+	for c > 0 {
+		if C.atomic_compare_exchange_weak_u32(&sem.count, &c, c - 1) {
+			return true
+		}
+	}
+	return false
+}
+
+pub fn (mut sem Semaphore) timed_wait(timeout time.Duration) bool {
+	mut c := C.atomic_load_u32(&sem.count)
+	for c > 0 {
+		if C.atomic_compare_exchange_weak_u32(&sem.count, &c, c - 1) {
+			return true
+		}
+	}
+	mut ft_start := C._FILETIME{}
+	C.GetSystemTimeAsFileTime(&ft_start)
+	time_end := ((u64(ft_start.dwHighDateTime) << 32) | ft_start.dwLowDateTime) +
+		u64(timeout / (100 * time.nanosecond))
+	mut t_ms := timeout.sys_milliseconds()
+	C.AcquireSRWLockExclusive(&sem.mtx)
+	mut res := 0
+	c = C.atomic_load_u32(&sem.count)
+
+	outer: for {
+		if c == 0 {
+			res = C.SleepConditionVariableSRW(&sem.cond, &sem.mtx, t_ms, 0)
+			if res == 0 {
+				break outer
+			}
+			c = C.atomic_load_u32(&sem.count)
+		}
+		for c > 0 {
+			if C.atomic_compare_exchange_weak_u32(&sem.count, &c, c - 1) {
+				if c > 1 {
+					C.WakeConditionVariable(&sem.cond)
+				}
+				break outer
+			}
+		}
+		C.GetSystemTimeAsFileTime(&ft_start)
+		time_now := ((u64(ft_start.dwHighDateTime) << 32) | ft_start.dwLowDateTime) // in 100ns
+		if time_now > time_end {
+			break outer // timeout exceeded
+		}
+		t_ms = u32((time_end - time_now) / 10000)
+	}
+	C.ReleaseSRWLockExclusive(&sem.mtx)
+	return res != 0
+}
+
+pub fn (s Semaphore) destroy() {
+}