Use hashlib.file_digest when available and applicable

This implementation is faster / more efficient than ours, but can only be used on binary-mode files.

Also increase the read buffer size to improve efficiency and performance.

wagtail/tests/test_utils.py

@@ -553,7 +553,7 @@ class HashFileLikeTestCase(SimpleTestCase):
             """
 
             def __init__(self):
-                self.iterations = 20000
+                self.iterations = 5000
 
             def read(self, bytes):
                 self.iterations -= 1
@@ -564,5 +564,5 @@ class HashFileLikeTestCase(SimpleTestCase):
 
         self.assertEqual(
             hash_filelike(FakeLargeFile()),
-            "187cc1db32624dccace20d042f6d631f1a483020",
+            "bd36f0c5a02cd6e9e34202ea3ff8db07b533e025",
         )

wagtail/utils/file.py

@@ -1,9 +1,9 @@
-from hashlib import sha1
+import hashlib
 from io import UnsupportedOperation
 
 from django.utils.encoding import force_bytes
 
-HASH_READ_SIZE = 65536  # 64k
+HASH_READ_SIZE = 2**18  # 256k - matches `hashlib.file_digest`
 
 
 def hash_filelike(filelike):
@@ -20,13 +20,23 @@ def hash_filelike(filelike):
     except (AttributeError, UnsupportedOperation):
         pass
 
-    hasher = sha1()
-    while True:
-        data = filelike.read(HASH_READ_SIZE)
-        if not data:
-            break
-        # Use `force_bytes` to account for files opened as text
-        hasher.update(force_bytes(data))
+    hasher = None
+
+    if hasattr(hashlib, "file_digest"):
+        try:
+            hasher = hashlib.file_digest(filelike, hashlib.sha1)
+        except ValueError:
+            # If the value can't be accepted by `file_digest` (eg text-mode files), use our fallback implementation
+            pass
+
+    if hasher is None:
+        hasher = hashlib.sha1()
+        while True:
+            data = filelike.read(HASH_READ_SIZE)
+            if not data:
+                break
+            # Use `force_bytes` to account for files opened as text
+            hasher.update(force_bytes(data))
 
     if hasattr(filelike, "seek"):
         # Reset the file handler to where it was before