Merge branch 'master' of https://intra.acdp.at/gogs/tanja/cdplib

cdplib/Singleton_Threadsafe.py

@@ -0,0 +1,41 @@
+import functools
+import threading
+
+lock = threading.Lock()
+
+def synchronized(lock):
+    """ Synchronization decorator """
+    def wrapper(f):
+        @functools.wraps(f)
+        def inner_wrapper(*args, **kw):
+            with lock:
+                return f(*args, **kw)
+        return inner_wrapper
+    return wrapper
+
+class SingletonThreadsafe(type):
+    _instances = {}
+
+    def __call__(cls, *args, **kwargs):
+        if cls not in cls._instances:
+            cls._locked_call(*args, **kwargs)
+        return cls._instances[cls]
+
+    @synchronized(lock)
+    def _locked_call(cls, *args, **kwargs):
+        if cls not in cls._instances:
+            cls._instances[cls] = super(SingletonThreadsafe, cls).__call__(*args, **kwargs)
+
+
+class testClass(metaclass=SingletonThreadsafe):
+    pass
+    def __init__(self, message: str = None):
+        self._message = message 
+
+if __name__ == "__main__":
+    x = testClass('hello')
+    y = testClass('yellow')
+
+    print(x==y)
+    print(x._message)
+    print(y._message)