feat(orc-452): shuffle ipfs providers on startup

Author: chasingrainbows

src/web3py/extensions/ipfs.py

@@ -1,4 +1,5 @@
 import logging
+import random
 from functools import wraps
 from typing import Iterable
 from web3 import Web3
@@ -27,11 +28,16 @@ class IPFS(Module):
     def __init__(self, w3: Web3, providers: Iterable[IPFSProvider], *, retries: int = 3) -> None:
         super().__init__(w3)
         self.retries = retries
-        self.providers = list(providers)
+
         self.current_provider_index: int = 0
         self.last_working_provider_index: int = 0
         self.current_frame: FrameNumber | None = None
 
+        self.providers = list(providers)
+        # Randomize provider order to reduce probability that
+        # all oracles use the same provider simultaneously in one frame
+        random.shuffle(self.providers)
+
         assert self.providers
 
         for p in self.providers:

tests/web3py/test_ipfs.py

@@ -59,7 +59,23 @@ def test_init__invalid_provider_type__raises_assertion_error(self, mock_w3):
         with pytest.raises(AssertionError):
             IPFS(mock_w3, ["not a provider"])
 
-    def test_provider_selection__different_frames__rotates_providers(self, mock_w3, mock_provider1, mock_provider2):
+    def test_providers_order__shuffled_once_at_init__order_remain_the_same_during_operations(
+        self, mock_w3, mock_provider1, mock_provider2
+    ):
+        ipfs = IPFS(mock_w3, [mock_provider1, mock_provider2])
+        initial_providers_order = ipfs.providers[:]
+
+        ipfs.fetch(HARDCODED_FETCH_CID, FrameNumber(0))
+        ipfs.publish(HARDCODED_PUBLISH_CONTENT, FrameNumber(1), "test")
+        ipfs.fetch(HARDCODED_FETCH_CID, FrameNumber(2))
+
+        assert ipfs.providers == initial_providers_order
+
+    @patch('random.shuffle')
+    def test_provider_selection__different_frames__rotates_providers(
+        self, mock_shuffle, mock_w3, mock_provider1, mock_provider2
+    ):
+        mock_shuffle.return_value = None
         ipfs = IPFS(mock_w3, [mock_provider1, mock_provider2])
 
         ipfs.fetch(HARDCODED_FETCH_CID, FrameNumber(0))
@@ -74,7 +90,11 @@ def test_provider_selection__different_frames__rotates_providers(self, mock_w3,
         ipfs.fetch(HARDCODED_FETCH_CID, FrameNumber(3))
         assert ipfs.provider == mock_provider2
 
-    def test_provider_selection__same_frame__keeps_same_provider(self, mock_w3, mock_provider1, mock_provider2):
+    @patch('random.shuffle')
+    def test_provider_selection__same_frame__keeps_same_provider(
+        self, mock_shuffle, mock_w3, mock_provider1, mock_provider2
+    ):
+        mock_shuffle.return_value = None
         ipfs = IPFS(mock_w3, [mock_provider1, mock_provider2])
 
         ipfs.fetch(HARDCODED_FETCH_CID, FrameNumber(1))
@@ -114,7 +134,11 @@ def test_fetch__all_retries_fail__raises_no_more_providers_error(self, mock_w3,
         assert isinstance(excinfo.value.__cause__, MaxRetryError)
         assert provider.fetch.call_count == 3
 
-    def test_fetch__first_provider_fails__falls_back_to_second_provider(self, mock_w3, mock_provider1, mock_provider2):
+    @patch('random.shuffle')
+    def test_fetch__first_provider_fails__falls_back_to_second_provider(
+        self, mock_shuffle, mock_w3, mock_provider1, mock_provider2
+    ):
+        mock_shuffle.return_value = None
         provider1 = mock_provider1
         provider1.fetch = MagicMock(side_effect=Exception("fail"))
         provider2 = mock_provider2
@@ -127,7 +151,11 @@ def test_fetch__first_provider_fails__falls_back_to_second_provider(self, mock_w
         assert provider1.fetch.call_count == 1
         assert provider2.fetch.call_count == 1
 
-    def test_fetch__all_providers_fail__raises_no_more_providers_error(self, mock_w3, mock_provider1, mock_provider2):
+    @patch('random.shuffle')
+    def test_fetch__all_providers_fail__raises_no_more_providers_error(
+        self, mock_shuffle, mock_w3, mock_provider1, mock_provider2
+    ):
+        mock_shuffle.return_value = None
         provider1 = mock_provider1
         provider1.fetch = MagicMock(side_effect=Exception("fail1"))
         provider2 = mock_provider2
@@ -159,9 +187,11 @@ def test_publish__all_retries_fail__raises_no_more_providers_error(self, mock_w3
         assert isinstance(excinfo.value.__cause__, MaxRetryError)
         assert provider.publish.call_count == 3
 
+    @patch('random.shuffle')
     def test_publish__first_provider_fails__falls_back_to_second_provider(
-        self, mock_w3, mock_provider1, mock_provider2
+        self, mock_shuffle, mock_w3, mock_provider1, mock_provider2
     ):
+        mock_shuffle.return_value = None
         provider1 = mock_provider1
         provider1.publish = MagicMock(side_effect=Exception("fail"))
         provider2 = mock_provider2
@@ -174,7 +204,11 @@ def test_publish__first_provider_fails__falls_back_to_second_provider(
         assert provider1.publish.call_count == 1
         assert provider2.publish.call_count == 1
 
-    def test_publish__all_providers_fail__raises_no_more_providers_error(self, mock_w3, mock_provider1, mock_provider2):
+    @patch('random.shuffle')
+    def test_publish__all_providers_fail__raises_no_more_providers_error(
+        self, mock_shuffle, mock_w3, mock_provider1, mock_provider2
+    ):
+        mock_shuffle.return_value = None
         provider1 = mock_provider1
         provider1.publish = MagicMock(side_effect=Exception("fail1"))
         provider2 = mock_provider2