Make RANDOM_KEY nonces thread-safe

src/ethproto/aa_bundler.py

@@ -1,6 +1,7 @@
 import random
 from collections import defaultdict
 from enum import Enum
+from threading import local
 from warnings import warn
 
 from environs import Env
@@ -54,7 +55,7 @@
 ]
 
 NONCE_CACHE = defaultdict(lambda: 0)
-RANDOM_NONCE_KEY = None
+RANDOM_NONCE_KEY = local()
 
 
 def pack_two(a, b):
@@ -140,10 +141,9 @@ def fetch_nonce(w3, account, entry_point, nonce_key):
 
 
 def get_random_nonce_key():
-    global RANDOM_NONCE_KEY
-    if RANDOM_NONCE_KEY is None:
-        RANDOM_NONCE_KEY = random.randint(1, 2**192 - 1)
-    return RANDOM_NONCE_KEY
+    if getattr(RANDOM_NONCE_KEY, "key", None) is None:
+        RANDOM_NONCE_KEY.key = random.randint(1, 2**192 - 1)
+    return RANDOM_NONCE_KEY.key
 
 
 def get_nonce_and_key(w3, tx, nonce_mode, entry_point=AA_BUNDLER_ENTRYPOINT, fetch=False):

tests/test_aa_bundler.py

@@ -1,3 +1,5 @@
+from queue import Queue
+from threading import Event, Thread
 from unittest.mock import MagicMock, patch
 
 from hexbytes import HexBytes
@@ -155,8 +157,8 @@ def test_get_nonce_random_key_mode(fetch_nonce_mock, randint_mock):
     fetch_nonce_mock.assert_not_called()
     randint_mock.assert_called_with(1, 2**192 - 1)
     randint_mock.reset_mock()
-    assert aa_bundler.RANDOM_NONCE_KEY == 444
-    aa_bundler.RANDOM_NONCE_KEY = None  # cleanup
+    assert aa_bundler.RANDOM_NONCE_KEY.key == 444
+    aa_bundler.RANDOM_NONCE_KEY.key = None  # cleanup
 
 
 @patch.object(aa_bundler.random, "randint")
@@ -241,3 +243,44 @@ def make_request(method, params):
     get_base_fee_mock.assert_called_once_with(w3)
     assert aa_bundler.NONCE_CACHE[0] == 1
     assert ret == {"userOpHash": "0xa950a17ca1ed83e974fb1aa227360a007cb65f566518af117ffdbb04d8d2d524"}
+
+
+def test_random_key_nonces_are_thread_safe():
+    queue = Queue()
+    event = Event()
+
+    def worker():
+        event.wait()  # Get all threads running at the same time
+        nonce_key, nonce = aa_bundler.get_nonce_and_key(
+            FAIL_IF_USED,
+            {"from": TEST_SENDER},
+            nonce_mode=aa_bundler.NonceMode.RANDOM_KEY,
+        )
+        aa_bundler.consume_nonce(nonce_key, nonce)
+        queue.put(
+            aa_bundler.get_nonce_and_key(
+                FAIL_IF_USED,
+                {"from": TEST_SENDER},
+                nonce_mode=aa_bundler.NonceMode.RANDOM_KEY,
+            )
+        )
+
+    threads = [Thread(target=worker) for _ in range(15)]
+    for thread in threads:
+        thread.start()
+
+    # Fire all threads at once
+    event.set()
+    for thread in threads:
+        thread.join()
+
+    nonces = {}
+
+    while not queue.empty():
+        nonce_key, nonce = queue.get_nowait()
+        # Each thread got a different key
+        assert nonce_key not in nonces
+        nonces[nonce_key] = nonce
+
+    # All nonces are the same
+    assert all(nonce == 1 for nonce in nonces.values())