Use siphash for persistent hashing

.pylintrc-local.yml

@@ -4,3 +4,4 @@
 - arg: ignored-modules
   val:
   - matplotlib
+  - siphash24

pyproject.toml

@@ -33,6 +33,7 @@ classifiers = [
 dependencies = [
     "platformdirs>=2.2",
     "typing-extensions>=4; python_version<'3.11'",
+    "siphash24>=1.6",
 ]
 
 [project.optional-dependencies]

pytools/persistent_dict.py

@@ -30,7 +30,6 @@
 """
 
 
-import hashlib
 import logging
 import os
 import pickle
@@ -52,6 +51,8 @@
     cast,
 )
 
+from siphash24 import siphash13
+
 
 if TYPE_CHECKING:
     from _typeshed import ReadableBuffer
@@ -160,7 +161,7 @@ class KeyBuilder:
 
     # this exists so that we can (conceivably) switch algorithms at some point
     # down the road
-    new_hash: Callable[..., Hash] = hashlib.sha256
+    new_hash: Callable[..., Hash] = siphash13
 
     def rec(self, key_hash: Hash, key: Any) -> Hash:
         """
@@ -301,7 +302,8 @@ def update_for_frozenset(self, key_hash: Hash, key: FrozenSet[Any]) -> None:
 
         unordered_hash(
             key_hash,
-            (self.rec(self.new_hash(), key_i).digest() for key_i in key))
+            (self.rec(self.new_hash(), key_i).digest() for key_i in key),
+            hash_constructor=self.new_hash)
 
     update_for_FrozenOrderedSet = update_for_frozenset  # noqa: N815
 
@@ -351,7 +353,8 @@ def update_for_frozendict(self, key_hash: Hash, key: Mapping[Any, Any]) -> None:
 
         unordered_hash(
             key_hash,
-            (self.rec(self.new_hash(), (k, v)).digest() for k, v in key.items()))
+            (self.rec(self.new_hash(), (k, v)).digest() for k, v in key.items()),
+            hash_constructor=self.new_hash)
 
     update_for_immutabledict = update_for_frozendict
     update_for_constantdict = update_for_frozendict

pytools/test/test_persistent_dict.py

@@ -548,17 +548,14 @@ class TagClass2(Tag):
     assert keyb(TagClass) != keyb(TagClass2)
     assert keyb(TagClass()) != keyb(TagClass2())
 
-    assert keyb(TagClass()) == \
-        "f5697a96dde0083e31a290b54ee7a5640b2bb8eb6d18e9c7ee89228b015a6131"
-    assert keyb(TagClass2) == \
-        "0833645765e32e7fb4a586614d0e345878eba50199ed2d8e963b28f797fd6e29"
+    assert keyb(TagClass()) == "7b3e4e66503438f6"
+    assert keyb(TagClass2) == "690b86bbf51aad83"
 
     @tag_dataclass
     class TagClass3(Tag):
         s: str
 
-    assert (keyb(TagClass3("foo"))  # type: ignore[call-arg]
-        == "c6521f4157ed530d04e956b7046db85e038c120b047cd1b848340d81f9fd8b4a")
+    assert (keyb(TagClass3("foo")) == "cf1a33652cc75b9c")  # type: ignore[call-arg]
 
 
 def test_dataclass_hashing() -> None:
@@ -569,8 +566,7 @@ class MyDC:
         name: str
         value: int
 
-    assert keyb(MyDC("hi", 1)) == \
-        "2ba6363c3b98f1cc2209bd57388368b3efe3074e3764eee30fbcf15946efb802"
+    assert keyb(MyDC("hi", 1)) == "d1a1079f1c10aa4f"
 
     assert keyb(MyDC("hi", 1)) == keyb(MyDC("hi", 1))
     assert keyb(MyDC("hi", 1)) != keyb(MyDC("hi", 2))
@@ -594,8 +590,7 @@ class MyAttrs:
         name: str
         value: int
 
-    assert (keyb(MyAttrs("hi", 1))  # type: ignore[call-arg]
-        == "17f272d114d22c1dc0117354777f2d506b303d90e10840d39fb0eef007252f68")
+    assert (keyb(MyAttrs("hi", 1)) == "5b6c5da60eb2bd0f")  # type: ignore[call-arg]
 
     assert keyb(MyAttrs("hi", 1)) == keyb(MyAttrs("hi", 1))  # type: ignore[call-arg]
     assert keyb(MyAttrs("hi", 1)) != keyb(MyAttrs("hi", 2))  # type: ignore[call-arg]
@@ -626,7 +621,7 @@ def test_datetime_hashing() -> None:
     # No timezone info; date is always naive
     assert (keyb(datetime.date(2020, 1, 1))
             == keyb(datetime.date(2020, 1, 1))
-            == "9fb97d7faabc3603f3e334ca5eb1eb0fe0c92665e5611cb1b5aa77fa0f70f5e3")
+            == "1c866ff10ff0d997")
     assert keyb(datetime.date(2020, 1, 1)) != keyb(datetime.date(2020, 1, 2))
 
     # }}}
@@ -640,7 +635,7 @@ def test_datetime_hashing() -> None:
             == keyb(datetime.time(12, 0))
             == keyb(datetime.time(12, 0, 0))
             == keyb(datetime.time(12, 0, 0, 0))
-            == "288ec82f6a00ac15968d4d257d4aca1089b863c61ef2ee200e64351238397705")
+            == "e523be74ebc6b227")
     assert keyb(datetime.time(12, 0)) != keyb(datetime.time(12, 1))
 
     # Aware time
@@ -653,7 +648,7 @@ def test_datetime_hashing() -> None:
     assert t1 == t2
     assert (keyb(t1)
             == keyb(t2)
-            == "3587427ca9d581779d532b397df206ddeadfcf4e38b1ee69c19174e8e1268cc4")
+            == "2041e7cd5b17b8eb")
 
     assert t1 != t3
     assert keyb(t1) != keyb(t3)
@@ -672,7 +667,7 @@ def test_datetime_hashing() -> None:
     assert dt1 == dt2
     assert (keyb(dt1)
             == keyb(dt2)
-            == "cd35722af47e42cb3bc81c389b87eb2e78ee8e20298bb1d8a193b30940d1c142")
+            == "8be96b9e739c7d8c")
 
     dt3 = datetime.datetime(2020, 1, 1, 7,
                             tzinfo=datetime.timezone(datetime.timedelta(hours=-4)))
@@ -688,7 +683,7 @@ def test_datetime_hashing() -> None:
     assert (keyb(datetime.datetime(2020, 1, 1))
             == keyb(datetime.datetime(2020, 1, 1))
             == keyb(datetime.datetime(2020, 1, 1, 0, 0, 0, 0))
-            == "8f3b843d7b9176afd8e2ce97ebc19789098a1c7774c4ec00d4054ec954ce2b88"
+            == "215dbe82add7a55c"
             )
     assert keyb(datetime.datetime(2020, 1, 1)) != keyb(datetime.datetime(2020, 1, 2))
     assert (keyb(datetime.datetime(2020, 1, 1))
@@ -711,7 +706,7 @@ def test_datetime_hashing() -> None:
     assert tz2 == tz3
     assert (keyb(tz2)
             == keyb(tz3)
-            == "89bd615f32c1f209b0853b1fc7d06ddb6fda7f367a00a8621d60337d52cb8d10")
+            == "5e1d46ab778c7ccf")
 
     # }}}
 
@@ -771,7 +766,7 @@ def test_size():
 
         size = pdict.nbytes()
         print("sqlite size: ", size/1024/1024, " MByte")
-        assert 1*1024*1024 < size < 2*1024*1024
+        assert 1024*1024//2 < size < 2*1024*1024
     finally:
         shutil.rmtree(tmpdir)
 
@@ -841,8 +836,7 @@ def test_hash_function() -> None:
 
     # {{{ global functions
 
-    assert keyb(global_fun) == keyb(global_fun) == \
-        "51b5980dd3a8aa13f6e83869e4a04c22973d7aaf96cb22899abdfdc55e15c9b2"
+    assert keyb(global_fun) == keyb(global_fun) == "79efd03f9a38ed77"
     assert keyb(global_fun) != keyb(global_fun2)
 
     # }}}
@@ -882,8 +876,7 @@ def local_fun():
     def local_fun2():
         pass
 
-    assert keyb(local_fun) == keyb(local_fun) == \
-        "fc58f5b0130df821913c848749eb03f5dcd4da7a568c6130f1c0cfb96ed0d12d"
+    assert keyb(local_fun) == keyb(local_fun) == "adc92e690b62dc2b"
     assert keyb(local_fun) != keyb(local_fun2)
 
     # }}}
@@ -898,8 +891,7 @@ class C2:
         def method(self):
             pass
 
-    assert keyb(C1.method) == keyb(C1.method) == \
-        "3013eb424dac133a57bd70cb6084d2a2f349a247714efc508fe3b10b99b6f717"
+    assert keyb(C1.method) == keyb(C1.method) == "af19e056ad7749c4"
     assert keyb(C1.method) != keyb(C2.method)
 
     # }}}