From 497fb9e21f45ec08e1486abaee6dfa7b20b8a691 Mon Sep 17 00:00:00 2001
From: Scott Gasch <scott@gasch.org>
Date: Wed, 24 Mar 2021 18:08:54 -0700
Subject: Initial revision

---
 smart_future.py | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 smart_future.py

(limited to 'smart_future.py')

diff --git a/smart_future.py b/smart_future.py
new file mode 100644
index 0000000..f1ffee1
--- /dev/null
+++ b/smart_future.py
@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+
+from __future__ import annotations
+from collections.abc import Mapping
+import concurrent.futures as fut
+import time
+from typing import Callable, List, TypeVar
+
+from deferred_operand import DeferredOperand
+import id_generator
+
+T = TypeVar('T')
+
+
+def wait_many(futures: List[SmartFuture], *, callback: Callable = None):
+    finished: Mapping[int, bool] = {}
+    x = 0
+    while True:
+        future = futures[x]
+        if not finished.get(future.get_id(), False):
+            if future.is_ready():
+                finished[future.get_id()] = True
+                yield future
+            else:
+                if callback is not None:
+                    callback()
+                time.sleep(0.1)
+        x += 1
+        if x >= len(futures):
+            x = 0
+        if len(finished) == len(futures):
+            if callback is not None:
+                callback()
+            return
+
+
+class SmartFuture(DeferredOperand):
+    """This is a SmartFuture, a class that wraps a normal Future and can
+    then be used, mostly, like a normal (non-Future) identifier.
+
+    Using a FutureWrapper in expressions will block and wait until
+    the result of the deferred operation is known.
+    """
+
+    def __init__(self, wrapped_future: fut.Future) -> None:
+        self.wrapped_future = wrapped_future
+        self.id = id_generator.get("smart_future_id")
+
+    def get_id(self) -> int:
+        return self.id
+
+    def is_ready(self) -> bool:
+        return self.wrapped_future.done()
+
+    # You shouldn't have to call this; instead, have a look at defining a
+    # method on DeferredOperand base class.
+    def _resolve(self, *, timeout=None) -> T:
+        return self.wrapped_future.result(timeout)
-- 
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