add

ccxt/async_support/base/ws/future.py

@@ -0,0 +1,46 @@
+import asyncio
+
+# Test by running:
+# - python python/ccxt/pro/test/base/test_close.py
+# - python python/ccxt/pro/test/base/test_future.py
+class Future(asyncio.Future):
+
+    def resolve(self, result=None):
+        if not self.done():
+            self.set_result(result)
+
+    def reject(self, error=None):
+        if not self.done():
+            self.set_exception(error)
+
+    @classmethod
+    def race(cls, futures):
+        future = Future()
+        coro = asyncio.wait(futures, return_when=asyncio.FIRST_COMPLETED)
+        task = asyncio.create_task(coro)
+
+        def callback(done):
+            complete, _ = done.result()
+            # check for exceptions
+            exceptions = []
+            cancelled = False
+            for f in complete:
+                if f.cancelled():
+                    cancelled = True
+                else:
+                    err = f.exception()
+                    if err:
+                        exceptions.append(err)
+            # if any exceptions return with first exception
+            if future.cancelled():
+                return
+            if len(exceptions) > 0:
+                future.set_exception(exceptions[0])
+            # else return first result
+            elif cancelled:
+                future.cancel()
+            else:
+                first_result = list(complete)[0].result()
+                future.set_result(first_result)
+        task.add_done_callback(callback)
+        return future