Make smart futures avoid polling.

[python_utils.git] / smart_future.py

diff --git a/smart_future.py b/smart_future.py
index 1c95973f48ab3bc3a0c9bcd90fa13498f851b8a9..c097d53b7c849867db4dd7f81121097397d0bee3 100644 (file)
--- a/smart_future.py
+++ b/smart_future.py
@@ -1,11 +1,12 @@
 #!/usr/bin/env python3
 
 from __future__ import annotations
-from collections.abc import Mapping
+import concurrent
 import concurrent.futures as fut
-import time
 from typing import Callable, List, TypeVar
 
+from overrides import overrides
+
 # This module is commonly used by others in here and should avoid
 # taking any unnecessary dependencies back on them.
 from deferred_operand import DeferredOperand
@@ -15,25 +16,33 @@ T = TypeVar('T')
 
 
 def wait_any(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):
+    real_futures = []
+    smart_future_by_real_future = {}
+    completed_futures = set()
+    for _ in futures:
+        real_futures.append(_.wrapped_future)
+        smart_future_by_real_future[_.wrapped_future] = _
+    while len(completed_futures) != len(real_futures):
+        newly_completed_futures = concurrent.futures.as_completed(real_futures)
+        for f in newly_completed_futures:
             if callback is not None:
                 callback()
-            return
+            completed_futures.add(f)
+            yield smart_future_by_real_future[f]
+    if callback is not None:
+        callback()
+    return
+
+
+def wait_all(futures: List[SmartFuture]) -> None:
+    real_futures = [x.wrapped_future for x in futures]
+    (done, not_done) = concurrent.futures.wait(
+        real_futures,
+        timeout=None,
+        return_when=concurrent.futures.ALL_COMPLETED
+    )
+    assert len(done) == len(real_futures)
+    assert len(not_done) == 0
 
 
 class SmartFuture(DeferredOperand):
@@ -56,5 +65,6 @@ class SmartFuture(DeferredOperand):
 
     # You shouldn't have to call this; instead, have a look at defining a
     # method on DeferredOperand base class.
+    @overrides
     def _resolve(self, *, timeout=None) -> T:
         return self.wrapped_future.result(timeout)