uasyncio.synchro: New submodule for synchronization primitives, Lock added.

uasyncio.synchro/uasyncio/synchro.py

@@ -0,0 +1,28 @@
+from uasyncio import core
+
+class Lock:
+
+    def __init__(self):
+        self.locked = False
+        self.wlist = []
+
+    def release(self):
+        assert self.locked
+        self.locked = False
+        if self.wlist:
+            #print(self.wlist)
+            coro = self.wlist.pop(0)
+            core.get_event_loop().call_soon(coro)
+
+    def acquire(self):
+        # As release() is not coro, assume we just released and going to acquire again
+        # so, yield first to let someone else to acquire it first
+        yield
+        #print("acquire:", self.locked)
+        while 1:
+            if not self.locked:
+                self.locked = True
+                return True
+            #print("putting", core.get_event_loop().cur_coro, "on waiting list")
+            self.wlist.append(core.get_event_loop().cur_coro)
+            yield False