From 4210f10e6e786d8908f3d9872edf3cd61b9d224c Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Thu, 17 Mar 2016 19:47:46 +0200
Subject: Compute faster whole-file checksum for non-MD5

---
 obnamlib/whole_file_checksummer.py       |  9 +++++++--
 obnamlib/whole_file_checksummer_tests.py | 13 ++++++++-----
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/obnamlib/whole_file_checksummer.py b/obnamlib/whole_file_checksummer.py
index b08655b9..0c49e05d 100644
--- a/obnamlib/whole_file_checksummer.py
+++ b/obnamlib/whole_file_checksummer.py
@@ -36,6 +36,7 @@ class WholeFileCheckSummer(object):
     '''
 
     def __init__(self, file_key):
+        self._all_bytes = file_key == obnamlib.REPO_FILE_MD5
         self._summer = self._create_checksum_algorithm(file_key)
 
     def _create_checksum_algorithm(self, file_key):
@@ -44,8 +45,12 @@ class WholeFileCheckSummer(object):
         name = obnamlib.get_checksum_algorithm_name(file_key)
         return obnamlib.get_checksum_algorithm(name)
 
-    def append_chunk(self, chunk_data, token):
-        self._summer.update(chunk_data)
+    def append_chunk(self, chunk_data, chunk_id):
+        if self._all_bytes:
+            self._summer.update(chunk_data)
+        else:
+            thing = '{},{};'.format(len(chunk_data), chunk_id)
+            self._summer.update(thing)
 
     def get_checksum(self):
         '''Get the current whole-file checksum.'''
diff --git a/obnamlib/whole_file_checksummer_tests.py b/obnamlib/whole_file_checksummer_tests.py
index c06becab..0b9c7b9f 100644
--- a/obnamlib/whole_file_checksummer_tests.py
+++ b/obnamlib/whole_file_checksummer_tests.py
@@ -16,6 +16,7 @@
 # =*= License: GPL-3+ =*=
 
 
+import hashlib
 import unittest
 
 import obnamlib
@@ -36,6 +37,7 @@ class WholeFileCheckSummerTests(unittest.TestCase):
         summer = obnamlib.WholeFileCheckSummer(obnamlib.REPO_FILE_MD5)
         chunk = 'hello'
         token = repo.prepare_chunk_for_indexes(chunk)
+        chunk_id = None
         summer.append_chunk(chunk, token)
         self.assertEqual(
             summer.get_checksum(),
@@ -46,11 +48,12 @@ class WholeFileCheckSummerTests(unittest.TestCase):
         summer = obnamlib.WholeFileCheckSummer(obnamlib.REPO_FILE_SHA512)
         chunk = 'hello'
         token = repo.prepare_chunk_for_indexes(chunk)
-        summer.append_chunk(chunk, token)
-        self.assertEqual(
-            summer.get_checksum(),
-            '9b71d224bd62f3785d96d46ad3ea3d73319bfbc2890caadae2dff72519673ca7'
-            '2323c3d99ba5c11d7c7acc6e14b8c5da0c4663475c2e5c3adef46f73bcdec043')
+        chunk_id = '123'
+        summer.append_chunk(chunk, chunk_id)
+
+        expected = hashlib.sha512('{},{};'.format(len(chunk), chunk_id))
+
+        self.assertEqual(summer.get_checksum(), expected.hexdigest())
 
 
 class FakeRepository(object):
-- 
cgit v1.2.1