perf: use hash() as sort key in stable repr and canonicalize JSON keys

src/cashet/hashing.py

@@ -347,7 +347,7 @@ def _stable_repr_to(
         _visited.add(obj_id)
         buf.write("{")
         first = True
-        for item in sorted(obj, key=repr):
+        for item in sorted(obj, key=hash):
             if not first:
                 buf.write(", ")
             first = False
@@ -362,7 +362,7 @@ def _stable_repr_to(
         _visited.add(obj_id)
         buf.write("frozenset({")
         first = True
-        for item in sorted(obj, key=repr):
+        for item in sorted(obj, key=hash):
             if not first:
                 buf.write(", ")
             first = False
@@ -377,7 +377,7 @@ def _stable_repr_to(
         _visited.add(obj_id)
         buf.write("{")
         first = True
-        for key, val in sorted(obj.items(), key=lambda p: repr(p[0])):
+        for key, val in sorted(obj.items(), key=lambda p: hash(p[0])):
             if not first:
                 buf.write(", ")
             first = False

src/cashet/store.py

@@ -306,20 +306,20 @@ def _put_commit_row(
                 commit.task_def.args_hash,
                 commit.task_def.args_snapshot,
                 commit.task_def.func_source,
-                json.dumps(commit.task_def.dep_versions),
+                json.dumps(commit.task_def.dep_versions, sort_keys=True),
                 int(commit.task_def.cache),
                 commit.task_def.retries,
                 int(commit.task_def.force),
                 timeout_seconds,
                 commit.task_def.ttl.total_seconds() if commit.task_def.ttl else None,
-                json.dumps([r.hash for r in commit.input_refs]),
+                json.dumps([r.hash for r in commit.input_refs], sort_keys=True),
                 output_hash,
                 output_size,
                 output_tier,
                 commit.parent_hash,
                 commit.status.value,
                 commit.error,
-                json.dumps(commit.tags),
+                json.dumps(commit.tags, sort_keys=True),
                 commit.created_at.isoformat(),
                 commit.claimed_at.isoformat(),
                 accessed_at,

tests/test_hashing.py

@@ -257,6 +257,26 @@ def identity(data: Any) -> Any:
         ref2 = client.submit(identity, {1: 2})
         assert ref1.hash != ref2.hash
 
+    def test_dict_insertion_order_invariant(self, client: Client) -> None:
+        def identity(data: Any) -> Any:
+            return data
+
+        d1 = {"x": 1, "y": 2, "z": 3}
+        d2 = {"z": 3, "y": 2, "x": 1}
+        ref1 = client.submit(identity, d1)
+        ref2 = client.submit(identity, d2)
+        assert ref1.hash == ref2.hash
+
+    def test_set_insertion_order_invariant(self, client: Client) -> None:
+        def identity(data: Any) -> Any:
+            return data
+
+        s1 = {"a", "b", "c"}
+        s2 = {"c", "b", "a"}
+        ref1 = client.submit(identity, s1)
+        ref2 = client.submit(identity, s2)
+        assert ref1.hash == ref2.hash
+
 
 class TestRecursiveStructures:
     def test_recursive_list_does_not_crash(self, client: Client) -> None: