sync: add .try_lock() to mutex/rwmutex, add tests (#20381)

vlib/sync/mutex_test.v

@@ -0,0 +1,42 @@
+import sync
+
+struct Counter {
+pub mut:
+	i int
+}
+
+fn write_10000(mut co Counter, mut mx sync.Mutex) {
+	mx.@lock()
+	co.i = 10000
+	mx.unlock()
+}
+
+fn test_mutex() {
+	mut co := &Counter{10086}
+	mut mx := sync.new_mutex()
+	mx.@lock()
+	co.i = 888
+	th := spawn write_10000(mut co, mut mx)
+	mx.unlock() // after mx unlock, thread write_10000 can continue
+	th.wait()
+	mx.destroy()
+	assert co.i == 10000
+}
+
+fn test_try_lock_mutex() {
+	// In Windows, try_lock only avalible after Windows 7
+	$if windows {
+		$if !windows_7 ? {
+			return
+		}
+	}
+	mut mx := sync.new_mutex()
+	mx.@lock()
+	try_fail := mx.try_lock()
+	assert try_fail == false
+	mx.unlock()
+	try_sucess := mx.try_lock()
+	assert try_sucess == true
+	mx.unlock() // you must unlock it, after try_lock sucess
+	mx.destroy()
+}

vlib/sync/rwmutex_test.v

@@ -0,0 +1,74 @@
+import sync
+import time
+
+struct Counter {
+pub mut:
+	i int
+}
+
+fn write_10000(mut co Counter, mut mx sync.RwMutex) {
+	mx.@lock()
+	co.i = 10000
+	mx.unlock()
+}
+
+fn test_rwmutex() {
+	mut co := &Counter{10086}
+	mut mx := sync.new_rwmutex()
+	mx.@lock()
+	co.i = 888
+	th1 := spawn write_10000(mut co, mut mx)
+	mx.unlock() // after mx unlock, thread write_10000 can continue
+	th1.wait()
+	assert co.i == 10000
+
+	mx.@rlock()
+	th2 := spawn write_10000(mut co, mut mx) // write_10000 will be blocked
+	co.i = 999 // for demo purpose, don't modify data in rlock!
+	time.sleep(1 * time.millisecond)
+	assert co.i == 999
+	mx.runlock() // after rlock released, write_10000 can continue
+	th2.wait()
+	assert co.i == 10000
+	mx.destroy()
+}
+
+fn test_try_lock_rwmutex() {
+	// In Windows, try_lock only avalible after Windows 7
+	$if windows {
+		$if !windows_7 ? {
+			return
+		}
+	}
+	mut mx := sync.new_rwmutex()
+
+	// try_rlock will always fail when mx locked
+	mx.@lock()
+	try_fail_reading1 := mx.try_rlock()
+	try_fail_writing1 := mx.try_wlock()
+	assert try_fail_reading1 == false
+	assert try_fail_writing1 == false
+
+	mx.unlock()
+
+	// try_rlock will always sucess when mx unlocked,
+	// multiple try_rlock can apply to the same mx
+	try_sucess_reading2 := mx.try_rlock()
+	try_sucess_reading3 := mx.try_rlock()
+	assert try_sucess_reading2 == true
+	assert try_sucess_reading3 == true
+
+	// if mx is rlocked, then the try_wlock will fail
+	try_fail_writing2 := mx.try_wlock()
+	assert try_fail_writing2 == false
+
+	mx.runlock()
+	mx.runlock() // you must release rlock mutiple times, as it was rlocked multiple times
+
+	// after mx release all rlock, try_wlock will sucess
+	try_sucess_writing3 := mx.try_wlock()
+	assert try_sucess_writing3 == true
+
+	mx.unlock() // you must unlock it, after try_wlock sucess
+	mx.destroy()
+}

vlib/sync/sync_darwin.c.v

@@ -12,6 +12,7 @@ import time
 @[trusted]
 fn C.pthread_mutex_init(voidptr, voidptr) int
 fn C.pthread_mutex_lock(voidptr) int
+fn C.pthread_mutex_trylock(voidptr) int
 fn C.pthread_mutex_unlock(voidptr) int
 fn C.pthread_mutex_destroy(voidptr) int
 fn C.pthread_rwlockattr_init(voidptr) int
@@ -20,6 +21,8 @@ fn C.pthread_rwlockattr_setpshared(voidptr, int) int
 fn C.pthread_rwlock_init(voidptr, voidptr) int
 fn C.pthread_rwlock_rdlock(voidptr) int
 fn C.pthread_rwlock_wrlock(voidptr) int
+fn C.pthread_rwlock_tryrdlock(voidptr) int
+fn C.pthread_rwlock_trywrlock(voidptr) int
 fn C.pthread_rwlock_unlock(voidptr) int
 fn C.pthread_rwlock_destroy(voidptr) int
 fn C.pthread_condattr_init(voidptr) int
@@ -119,6 +122,13 @@ pub fn (mut m Mutex) @lock() {
 	C.pthread_mutex_lock(&m.mutex)
 }
 
+// try_lock try to lock the mutex instance and return immediately.
+// If the mutex was already locked, it will return false.
+@[inline]
+pub fn (mut m Mutex) try_lock() bool {
+	return C.pthread_mutex_trylock(&m.mutex) == 0
+}
+
 // unlock unlocks the mutex instance. The mutex is released, and one of
 // the other threads, that were blocked, because they called @lock can continue.
 @[inline]
@@ -158,6 +168,20 @@ pub fn (mut m RwMutex) @lock() {
 	C.pthread_rwlock_wrlock(&m.mutex)
 }
 
+// try_rlock try to lock the given RwMutex instance for reading and return immediately.
+// If the mutex was already locked, it will return false.
+@[inline]
+pub fn (mut m RwMutex) try_rlock() bool {
+	return C.pthread_rwlock_tryrdlock(&m.mutex) == 0
+}
+
+// try_wlock try to lock the given RwMutex instance for writing and return immediately.
+// If the mutex was already locked, it will return false.
+@[inline]
+pub fn (mut m RwMutex) try_wlock() bool {
+	return C.pthread_rwlock_trywrlock(&m.mutex) == 0
+}
+
 // destroy frees the resources associated with the rwmutex instance.
 // Note: the mutex itself is not freed.
 @[inline]

vlib/sync/sync_default.c.v

@@ -16,6 +16,7 @@ $if !android {
 @[trusted]
 fn C.pthread_mutex_init(voidptr, voidptr) int
 fn C.pthread_mutex_lock(voidptr) int
+fn C.pthread_mutex_trylock(voidptr) int
 fn C.pthread_mutex_unlock(voidptr) int
 fn C.pthread_mutex_destroy(voidptr) int
 fn C.pthread_rwlockattr_init(voidptr) int
@@ -25,6 +26,8 @@ fn C.pthread_rwlockattr_destroy(voidptr) int
 fn C.pthread_rwlock_init(voidptr, voidptr) int
 fn C.pthread_rwlock_rdlock(voidptr) int
 fn C.pthread_rwlock_wrlock(voidptr) int
+fn C.pthread_rwlock_tryrdlock(voidptr) int
+fn C.pthread_rwlock_trywrlock(voidptr) int
 fn C.pthread_rwlock_unlock(voidptr) int
 fn C.pthread_rwlock_destroy(voidptr) int
 fn C.sem_init(voidptr, int, u32) int
@@ -106,6 +109,13 @@ pub fn (mut m Mutex) @lock() {
 	C.pthread_mutex_lock(&m.mutex)
 }
 
+// try_lock try to lock the mutex instance and return immediately.
+// If the mutex was already locked, it will return false.
+@[inline]
+pub fn (mut m Mutex) try_lock() bool {
+	return C.pthread_mutex_trylock(&m.mutex) == 0
+}
+
 // unlock unlocks the mutex instance. The mutex is released, and one of
 // the other threads, that were blocked, because they called @lock can continue.
 @[inline]
@@ -144,6 +154,20 @@ pub fn (mut m RwMutex) @lock() {
 	C.pthread_rwlock_wrlock(&m.mutex)
 }
 
+// try_rlock try to lock the given RwMutex instance for reading and return immediately.
+// If the mutex was already locked, it will return false.
+@[inline]
+pub fn (mut m RwMutex) try_rlock() bool {
+	return C.pthread_rwlock_tryrdlock(&m.mutex) == 0
+}
+
+// try_wlock try to lock the given RwMutex instance for writing and return immediately.
+// If the mutex was already locked, it will return false.
+@[inline]
+pub fn (mut m RwMutex) try_wlock() bool {
+	return C.pthread_rwlock_trywrlock(&m.mutex) == 0
+}
+
 // destroy frees the resources associated with the rwmutex instance.
 // Note: the mutex itself is not freed.
 pub fn (mut m RwMutex) destroy() {

vlib/sync/sync_windows.c.v

@@ -76,6 +76,19 @@ pub fn (mut m Mutex) @lock() {
 	C.AcquireSRWLockExclusive(&m.mx)
 }
 
+// try_lock try to lock the mutex instance and return immediately.
+// If the mutex was already locked, it will return false.
+// NOTE: try_lock require Windows 7 or later. Before Windows 7, it will always return false.
+// NOTE: To enable try_lock , you should compile your project with `-d windows_7`, like `v . -d windows_7`
+// https://learn.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-tryacquiresrwlockexclusive
+pub fn (mut m Mutex) try_lock() bool {
+	$if windows_7 ? {
+		return C.TryAcquireSRWLockExclusive(&m.mx) != 0
+	} $else {
+		return false
+	}
+}
+
 pub fn (mut m Mutex) unlock() {
 	C.ReleaseSRWLockExclusive(&m.mx)
 }
@@ -89,6 +102,32 @@ pub fn (mut m RwMutex) @lock() {
 	C.AcquireSRWLockExclusive(&m.mx)
 }
 
+// try_rlock try to lock the given RwMutex instance for reading and return immediately.
+// If the mutex was already locked, it will return false.
+// NOTE: try_rlock require Windows 7 or later. Before Windows 7, it will always return false.
+// NOTE: To enable try_rlock , you should compile your project with `-d windows_7`, like `v . -d windows_7`
+// https://learn.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-tryacquiresrwlockshared
+pub fn (mut m RwMutex) try_rlock() bool {
+	$if windows_7 ? {
+		return C.TryAcquireSRWLockShared(&m.mx) != 0
+	} $else {
+		return false
+	}
+}
+
+// try_wlock try to lock the given RwMutex instance for writing and return immediately.
+// If the mutex was already locked, it will return false.
+// NOTE: try_wlock require Windows 7 or later. Before Windows 7, it will always return false.
+// NOTE: To enable try_wlock , you should compile your project with `-d windows_7`, like `v . -d windows_7`
+// https://learn.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-tryacquiresrwlockexclusive
+pub fn (mut m RwMutex) try_wlock() bool {
+	$if windows_7 ? {
+		return C.TryAcquireSRWLockExclusive(&m.mx) != 0
+	} $else {
+		return false
+	}
+}
+
 // Windows SRWLocks have different function to unlock
 // So provide two functions here, too, to have a common interface
 pub fn (mut m RwMutex) runlock() {