From 32b3611026896863d75801c9ded79685e6dd00ee Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Fri, 25 Oct 2019 17:24:40 +0300
Subject: [PATCH] sync: new_mutex() and new_waitgroup()

---
 examples/news_fetcher.v                  | 15 +++++++++------
 vlib/sync/sync_nix.v                     |  8 ++++++++
 vlib/sync/{sync_win.v => sync_windows.v} | 20 +++++++++++++++++---
 vlib/sync/waitgroup.v                    |  7 +++++++
 4 files changed, 41 insertions(+), 9 deletions(-)
 rename vlib/sync/{sync_win.v => sync_windows.v} (76%)

diff --git a/examples/news_fetcher.v b/examples/news_fetcher.v
index 4dd16fa967..dce80a2487 100644
--- a/examples/news_fetcher.v
+++ b/examples/news_fetcher.v
@@ -17,10 +17,10 @@ struct Story {
 
 struct Fetcher {
 mut:
-	mu      sync.Mutex
+	mu      &sync.Mutex
 	ids     []int
 	cursor  int
-	wg		&sync.WaitGroup
+	wg      &sync.WaitGroup
 }
 
 fn (f mut Fetcher) fetch() {
@@ -65,12 +65,15 @@ fn main() {
 		ids = tmp
 	}
 	
-	mut wg := &sync.WaitGroup{}
-	fetcher := &Fetcher{ids: ids, wg: wg} // wg sent via ptr
-	wg.add(ids.len)
+	wg := sync.new_waitgroup()
+	mtx := sync.new_mutex()
+	mut fetcher := &Fetcher{ids: ids}
+	fetcher.mu = &mtx
+	fetcher.wg = &wg
+	fetcher.wg.add(ids.len)
 	for i := 0; i < NR_THREADS; i++ {
 		go fetcher.fetch()
 	}
-	wg.wait()
+	fetcher.wg.wait()
 }
 
diff --git a/vlib/sync/sync_nix.v b/vlib/sync/sync_nix.v
index 46707bd8b0..2287a81d6d 100644
--- a/vlib/sync/sync_nix.v
+++ b/vlib/sync/sync_nix.v
@@ -5,10 +5,18 @@
 module sync
 
 #include <pthread.h>
+
+//[init_with=new_mutex] // TODO: implement support for this struct attribute, and disallow Mutex{} from outside the sync.new_mutex() function.
 pub struct Mutex {
 	mutex C.pthread_mutex_t
 }
 
+pub fn new_mutex() Mutex {
+	m := Mutex{}
+	C.pthread_mutex_init( &m.mutex, C.NULL)
+	return m
+}
+
 pub fn (m mut Mutex) lock() {
 	C.pthread_mutex_lock(&m.mutex)
 }
diff --git a/vlib/sync/sync_win.v b/vlib/sync/sync_windows.v
similarity index 76%
rename from vlib/sync/sync_win.v
rename to vlib/sync/sync_windows.v
index be540803eb..a2fdef37b0 100644
--- a/vlib/sync/sync_win.v
+++ b/vlib/sync/sync_windows.v
@@ -7,6 +7,7 @@ module sync
 // Mutex HANDLE
 type MHANDLE voidptr
 
+//[init_with=new_mutex] // TODO: implement support for this struct attribute, and disallow Mutex{} from outside the sync.new_mutex() function.
 pub struct Mutex {
 mut:
 	mx           MHANDLE    // mutex handle
@@ -38,6 +39,19 @@ const (
 	WAIT_FAILED        = 0xFFFFFFFF
 )
 
+pub fn new_mutex() Mutex {
+	sm := Mutex{}
+	unsafe {
+		mut m := sm		
+		m.mx = C.CreateMutex(0, false, 0)
+		if isnil(m.mx) {
+			m.state = .broken // handle broken and mutex state are broken
+			return sm
+		}		
+		return sm
+	}
+}
+
 pub fn (m mut Mutex) lock() {
 	// if mutex handle not initalized
 	if isnil(m.mx) {
@@ -49,9 +63,9 @@ pub fn (m mut Mutex) lock() {
 	}
 	state := C.WaitForSingleObject(m.mx, INFINITE) // infinite wait
 	m.state = match state {
-		WAIT_ABANDONED => { MutexState.abandoned }
-		WAIT_OBJECT_0  => { MutexState.waiting }
-		else           => { MutexState.broken }
+		WAIT_ABANDONED { MutexState.abandoned }
+		WAIT_OBJECT_0  { MutexState.waiting }
+		else           { MutexState.broken }
 	}
 }
 
diff --git a/vlib/sync/waitgroup.v b/vlib/sync/waitgroup.v
index 669401e4e7..307192e824 100644
--- a/vlib/sync/waitgroup.v
+++ b/vlib/sync/waitgroup.v
@@ -4,12 +4,19 @@
 
 module sync
 
+//[init_with=new_waitgroup] // TODO: implement support for init_with struct attribute, and disallow WaitGroup{} from outside the sync.new_waitgroup() function.
 pub struct WaitGroup {
 mut:
 	mu Mutex
 	active int
 }
 
+pub fn new_waitgroup() WaitGroup {
+	mut w := WaitGroup{}
+	w.mu = sync.new_mutex()
+	return w
+}
+
 pub fn (wg mut WaitGroup) add(delta int) {
 	wg.mu.lock()
 	wg.active += delta