From 3bae76070592c8057df3ffbd9119b77f7f9c72f6 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sun, 21 Aug 2022 08:28:07 +0530
Subject: [PATCH] Micro-optimization

---
 src/calibre/db/backend.py       | 32 +++++++++++++++++++-------------
 src/calibre/db/tests/reading.py |  8 +++++++-
 2 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index ae421b0080..4115740583 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -8,7 +8,6 @@ __docformat__ = 'restructuredtext en'
 # Imports {{{
 import apsw
 import errno
-import glob
 import hashlib
 import json
 import os
@@ -1435,18 +1434,25 @@ class DB:
         fmt_path = os.path.join(path, fname+fmt)
         if os.path.exists(fmt_path):
             return fmt_path
-        try:
-            candidates = glob.glob(os.path.join(path, '*'+fmt))
-        except:  # If path contains strange characters this throws an exc
-            candidates = []
-        if fmt and candidates and os.path.exists(candidates[0]):
-            try:
-                shutil.copyfile(candidates[0], fmt_path)
-            except shutil.SameFileError:
-                # some other process synced in the file since the last
-                # os.path.exists()
-                return candidates[0]
-            return fmt_path
+        if not fmt:
+            return
+        candidates = ()
+        with suppress(OSError):
+            candidates = os.listdir(path)
+        q = fmt.lower()
+        for x in candidates:
+            if x.lower().endswith(q):
+                x = os.path.join(path, x)
+                with suppress(OSError):
+                    atomic_rename(x, fmt_path)
+                    return fmt_path
+                try:
+                    shutil.move(x, fmt_path)
+                except (shutil.SameFileError, OSError):
+                    # some other process synced in the file since the last
+                    # os.path.exists()
+                    return x
+                return fmt_path
 
     def cover_abspath(self, book_id, path):
         path = os.path.join(self.library_path, path)
diff --git a/src/calibre/db/tests/reading.py b/src/calibre/db/tests/reading.py
index fc0fd88955..5a46bcca4e 100644
--- a/src/calibre/db/tests/reading.py
+++ b/src/calibre/db/tests/reading.py
@@ -5,7 +5,7 @@ __license__   = 'GPL v3'
 __copyright__ = '2011, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
-import datetime
+import datetime, os
 from io import BytesIO
 from time import time
 
@@ -455,6 +455,12 @@ class ReadingTest(BaseTest):
         buf = BytesIO()
         self.assertRaises(NoSuchFormat, cache.copy_format_to, 99999, 'X', buf, 'copy_format_to() failed to raise an exception for non-existent book')
         self.assertRaises(NoSuchFormat, cache.copy_format_to, 1, 'X', buf, 'copy_format_to() failed to raise an exception for non-existent format')
+        fmt = cache.formats(1)[0]
+        path = cache.format_abspath(1, fmt)
+        changed_path = os.path.join(os.path.dirname(path), 'x' + os.path.basename(path))
+        os.rename(path, changed_path)
+        self.assertEqual(cache.format_abspath(1, fmt), path)
+        self.assertFalse(os.path.exists(changed_path))
 
     # }}}