Use platform independant hashing for transformations.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

HISTORY.rst

@@ -91,6 +91,7 @@
   DOCUMENTS_RECENT_COUNT has been renamed to
   DOCUMENTS_RECENT_ACCESS_COUNT. New setting 
   DOCUMENTS_RECENT_ADDED_COUNT added.
+- Use platform independant hashing for transformations.
 
 3.0.3 (2018-08-17)
 ==================

mayan/apps/converter/tests/literals.py

@@ -2,3 +2,14 @@ from __future__ import unicode_literals
 
 TEST_TRANSFORMATION_NAME = 'rotate'
 TEST_TRANSFORMATION_ARGUMENT = 'degrees: 180'
+TEST_TRANSFORMATION_COMBINED_CACHE_HASH = '384bf78014d2aed7255d9e548a0694c70af0b22545653214bcceb1ac6286b5f7'
+TEST_TRANSFORMATION_RESIZE_CACHE_HASH = '4aa319f5a6950985a19380a1f279a66769d04138bd1583844270fe8c269260fc'
+TEST_TRANSFORMATION_RESIZE_CACHE_HASH_2 = 'cc8d220d40e810b995181c0c69b44b7a61c3bb039c0be96a5465fcaf698ca99a'
+TEST_TRANSFORMATION_RESIZE_HEIGHT = 528
+TEST_TRANSFORMATION_RESIZE_HEIGHT_2 = 529
+TEST_TRANSFORMATION_RESIZE_WIDTH = 123
+TEST_TRANSFORMATION_RESIZE_WIDTH_2 = 124
+TEST_TRANSFORMATION_ROTATE_CACHE_HASH = 'df6a5854fccdd3a56145fcd7f7bf52bdf95fe940d6611d435e80dfcaca3b61ac'
+TEST_TRANSFORMATION_ROTATE_DEGRESS = 34
+TEST_TRANSFORMATION_ZOOM_CACHE_HASH = 'ac7a864de6a95889d5892301e142f8cdc5808f55010c0b820ed056902fc25a73'
+TEST_TRANSFORMATION_ZOOM_PERCENT = 49

mayan/apps/converter/tests/test_transformations.py

@@ -10,17 +10,19 @@ from ..transformations import (
     TransformationRotate, TransformationZoom
 )
 
-TRANSFORMATION_RESIZE_WIDTH = 123
-TRANSFORMATION_RESIZE_HEIGHT = 528
-TRANSFORMATION_RESIZE_CACHE_HASH = '348d60cb7c028c95'
-TRANSFORMATION_RESIZE_WIDTH_2 = 124
-TRANSFORMATION_RESIZE_HEIGHT_2 = 529
-TRANSFORMATION_RESIZE_CACHE_HASH_2 = '348d78cb5709c1bf'
-TRANSFORMATION_ROTATE_DEGRESS = 34
-TRANSFORMATION_ROTATE_CACHE_HASH = '45148f480ad5f8bd'
-TRANSFORMATION_COMBINED_CACHE_HASH = '1267dbe78a1759da'
-TRANSFORMATION_ZOOM_PERCENT = 49
-TRANSFORMATION_ZOOM_CACHE_HASH = '1b333603674469e0'
+from .literals import (
+    TEST_TRANSFORMATION_COMBINED_CACHE_HASH,
+    TEST_TRANSFORMATION_RESIZE_CACHE_HASH,
+    TEST_TRANSFORMATION_RESIZE_CACHE_HASH_2,
+    TEST_TRANSFORMATION_RESIZE_HEIGHT,
+    TEST_TRANSFORMATION_RESIZE_HEIGHT_2,
+    TEST_TRANSFORMATION_RESIZE_WIDTH,
+    TEST_TRANSFORMATION_RESIZE_WIDTH_2,
+    TEST_TRANSFORMATION_ROTATE_CACHE_HASH,
+    TEST_TRANSFORMATION_ROTATE_DEGRESS,
+    TEST_TRANSFORMATION_ZOOM_CACHE_HASH,
+    TEST_TRANSFORMATION_ZOOM_PERCENT,
+)
 
 
 class TransformationBaseTestCase(TestCase):
@@ -45,64 +47,65 @@ class TransformationBaseTestCase(TestCase):
     def test_resize_cache_hashing(self):
         # Test if the hash is being generated correctly
         transformation = TransformationResize(
-            width=TRANSFORMATION_RESIZE_WIDTH,
-            height=TRANSFORMATION_RESIZE_HEIGHT
+            width=TEST_TRANSFORMATION_RESIZE_WIDTH,
+            height=TEST_TRANSFORMATION_RESIZE_HEIGHT
         )
 
         self.assertEqual(
-            transformation.cache_hash(), TRANSFORMATION_RESIZE_CACHE_HASH
+            transformation.cache_hash(), TEST_TRANSFORMATION_RESIZE_CACHE_HASH
         )
 
         # Test if the hash is being alternated correctly
         transformation = TransformationResize(
-            width=TRANSFORMATION_RESIZE_WIDTH_2,
-            height=TRANSFORMATION_RESIZE_HEIGHT_2
+            width=TEST_TRANSFORMATION_RESIZE_WIDTH_2,
+            height=TEST_TRANSFORMATION_RESIZE_HEIGHT_2
         )
 
         self.assertEqual(
-            transformation.cache_hash(), TRANSFORMATION_RESIZE_CACHE_HASH_2
+            transformation.cache_hash(),
+            TEST_TRANSFORMATION_RESIZE_CACHE_HASH_2
         )
 
     def test_rotate_cache_hashing(self):
         # Test if the hash is being generated correctly
         transformation = TransformationRotate(
-            degrees=TRANSFORMATION_ROTATE_DEGRESS
+            degrees=TEST_TRANSFORMATION_ROTATE_DEGRESS
         )
 
         self.assertEqual(
-            transformation.cache_hash(), TRANSFORMATION_ROTATE_CACHE_HASH
+            transformation.cache_hash(), TEST_TRANSFORMATION_ROTATE_CACHE_HASH
         )
 
     def test_rotate_zoom_hashing(self):
         # Test if the hash is being generated correctly
         transformation = TransformationZoom(
-            percent=TRANSFORMATION_ZOOM_PERCENT
+            percent=TEST_TRANSFORMATION_ZOOM_PERCENT
         )
 
         self.assertEqual(
-            transformation.cache_hash(), TRANSFORMATION_ZOOM_CACHE_HASH
+            transformation.cache_hash(), TEST_TRANSFORMATION_ZOOM_CACHE_HASH
         )
 
     def test_cache_hash_combining(self):
         # Test magic method and hash combining
 
         transformation_resize = TransformationResize(
-            width=TRANSFORMATION_RESIZE_WIDTH,
-            height=TRANSFORMATION_RESIZE_HEIGHT
+            width=TEST_TRANSFORMATION_RESIZE_WIDTH,
+            height=TEST_TRANSFORMATION_RESIZE_HEIGHT
         )
 
         transformation_rotate = TransformationRotate(
-            degrees=TRANSFORMATION_ROTATE_DEGRESS
+            degrees=TEST_TRANSFORMATION_ROTATE_DEGRESS
         )
 
         transformation_zoom = TransformationZoom(
-            percent=TRANSFORMATION_ZOOM_PERCENT
+            percent=TEST_TRANSFORMATION_ZOOM_PERCENT
         )
 
         self.assertEqual(
             BaseTransformation.combine(
                 (transformation_rotate, transformation_resize, transformation_zoom)
-            ), TRANSFORMATION_COMBINED_CACHE_HASH
+            ), TEST_TRANSFORMATION_COMBINED_CACHE_HASH
         )
 
 

mayan/apps/converter/transformations.py

@@ -1,11 +1,12 @@
 from __future__ import unicode_literals
 
+import hashlib
 import logging
 
 from PIL import Image, ImageColor, ImageFilter
 
-from django.utils.six import text_type
 from django.utils.translation import string_concat, ugettext_lazy as _
+from django.utils.encoding import force_text
 
 logger = logging.getLogger(__name__)
 
@@ -19,25 +20,17 @@ class BaseTransformation(object):
     name = 'base_transformation'
     _registry = {}
 
-    @staticmethod
-    def encode_hash(decoded_value):
-        return hex(abs(decoded_value))[2:]
-
-    @staticmethod
-    def decode_hash(encoded_value):
-        return int(encoded_value, 16)
-
     @staticmethod
     def combine(transformations):
         result = None
 
-        for index, transformation in enumerate(transformations):
+        for transformation in transformations:
             if not result:
-                result = hash((BaseTransformation.decode_hash(transformation.cache_hash()), index))
+                result = hashlib.sha256(transformation.cache_hash())
             else:
-                result ^= hash((BaseTransformation.decode_hash(transformation.cache_hash()), index))
+                result.update(transformation.cache_hash())
 
-        return BaseTransformation.encode_hash(result)
+        return result.hexdigest()
 
     @classmethod
     def register(cls, transformation):
@@ -69,11 +62,14 @@ class BaseTransformation(object):
             self.kwargs[argument_name] = kwargs.get(argument_name)
 
     def cache_hash(self):
-        result = text_type.__hash__(self.name)
-        for index, (key, value) in enumerate(self.kwargs.items()):
-            result ^= hash((key, index)) ^ hash((value, index))
+        result = hashlib.sha256(self.name)
 
-        return BaseTransformation.encode_hash(result)
+        # Sort arguments for guaranteed repeatability
+        for key, value in sorted(self.kwargs.items()):
+            result.update(force_text(key))
+            result.update(force_text(value))
+
+        return result.hexdigest()
 
     def execute_on(self, image):
         self.image = image