[pitivi] previewers: Improved cached files naming

[Alexandru Băluț <alexbalut src gnome org>]

commit 4408f60e8d4bc20d0777d591742b79665eff9885
Author: Vivek R <123vivekr gmail com>
Date:   Mon Jan 27 12:20:54 2020 +0530

    previewers: Improved cached files naming
    
    Fixes #2377

 pitivi/timeline/previewers.py | 34 +++++++++++++++++++++++++++++-----
 pitivi/utils/misc.py          | 13 -------------
 tests/test_previewers.py      | 17 +++++++++++++++++
 3 files changed, 46 insertions(+), 18 deletions(-)
---
diff --git a/pitivi/timeline/previewers.py b/pitivi/timeline/previewers.py
index 0660df63..531b1cf1 100644
--- a/pitivi/timeline/previewers.py
+++ b/pitivi/timeline/previewers.py
@@ -16,6 +16,7 @@
 # License along with this program; if not, see <http://www.gnu.org/licenses/>.
 """Previewers for the timeline."""
 import contextlib
+import hashlib
 import os
 import random
 import sqlite3
@@ -33,7 +34,6 @@ from gi.repository import Gtk
 from pitivi.settings import GlobalSettings
 from pitivi.settings import xdg_cache_home
 from pitivi.utils.loggable import Loggable
-from pitivi.utils.misc import hash_file
 from pitivi.utils.misc import path_from_uri
 from pitivi.utils.misc import quantize
 from pitivi.utils.misc import quote_uri
@@ -940,8 +940,14 @@ class ThumbnailCache(Loggable):
     @staticmethod
     def dbfile_name(uri):
         """Returns the cache file path for the specified URI."""
-        filename = hash_file(Gst.uri_get_location(uri))
-        thumbs_cache_dir = xdg_cache_home("thumbs")
+        filename = gen_filename(Gst.uri_get_location(uri), "db")
+        thumbs_dir = xdg_cache_home("thumbs")
+        thumbs_cache_dir = os.path.join(thumbs_dir, "v1")
+
+        if not os.path.exists(thumbs_cache_dir):
+            os.makedirs(thumbs_cache_dir)
+            GLib.idle_add(delete_all_files_in_dir, thumbs_dir)
+
         return os.path.join(thumbs_cache_dir, filename)
 
     @classmethod
@@ -1070,12 +1076,30 @@ class ThumbnailCache(Loggable):
         self.log("Saved thumbnail cache file")
 
 
+def delete_all_files_in_dir(path):
+    """Deletes the files in path without descending into subdirectories."""
+    for dir_entry in os.scandir(path):
+        if dir_entry.is_file() or dir_entry.is_symlink():
+            os.unlink(dir_entry.path)
+
+
+def gen_filename(uri, extension):
+    """Generates the cache filename for the specified URI."""
+    uri_hash = hashlib.sha256(uri.encode("UTF-8")).hexdigest()
+    return "{}_{}_{}.{}".format(os.path.basename(uri), uri_hash, os.path.getmtime(uri), extension)
+
+
 def get_wavefile_location_for_uri(uri):
     """Computes the URI where the wave.npy file should be stored."""
     if ProxyManager.is_proxy_asset(uri):
         uri = ProxyManager.get_target_uri(uri)
-    filename = hash_file(Gst.uri_get_location(uri)) + ".wave.npy"
-    cache_dir = xdg_cache_home("waves")
+    filename = gen_filename(Gst.uri_get_location(uri), "wave.npy")
+    waves_dir = xdg_cache_home("waves")
+    cache_dir = os.path.join(waves_dir, "v1")
+
+    if not os.path.exists(cache_dir):
+        os.makedirs(cache_dir)
+        GLib.idle_add(delete_all_files_in_dir, waves_dir)
 
     return os.path.join(cache_dir, filename)
 
diff --git a/pitivi/utils/misc.py b/pitivi/utils/misc.py
index 70f93485..ba844e76 100644
--- a/pitivi/utils/misc.py
+++ b/pitivi/utils/misc.py
@@ -15,7 +15,6 @@
 #
 # You should have received a copy of the GNU Lesser General Public
 # License along with this program; if not, see <http://www.gnu.org/licenses/>.
-import hashlib
 import os
 import subprocess
 import threading
@@ -223,18 +222,6 @@ class PathWalker(Thread):
         self.stopme.set()
 
 
-def hash_file(uri):
-    """Hashes the first 256KB of the specified file."""
-    sha256 = hashlib.sha256()
-    with open(uri, "rb") as file:
-        for unused in range(1024):
-            chunk = file.read(256)
-            if not chunk:
-                break
-            sha256.update(chunk)
-    return sha256.hexdigest()
-
-
 def quantize(value, interval):
     return (value // interval) * interval
 
diff --git a/tests/test_previewers.py b/tests/test_previewers.py
index 0e7cbf5e..2f0dfcf3 100644
--- a/tests/test_previewers.py
+++ b/tests/test_previewers.py
@@ -25,6 +25,7 @@ from gi.repository import GdkPixbuf
 from gi.repository import GES
 from gi.repository import Gst
 
+from pitivi.timeline.previewers import delete_all_files_in_dir
 from pitivi.timeline.previewers import get_wavefile_location_for_uri
 from pitivi.timeline.previewers import Previewer
 from pitivi.timeline.previewers import THUMB_HEIGHT
@@ -170,3 +171,19 @@ class TestThumbnailCache(BaseTestMediaLibrary):
                 thumb_cache = ThumbnailCache(sample_uri)
                 self.assertTrue(Gst.SECOND in thumb_cache)
                 self.assertIsNotNone(thumb_cache[Gst.SECOND])
+
+
+class TestFunctions(BaseTestMediaLibrary):
+    """Tests for the standalone functions."""
+
+    def test_delete_all_files_in_dir(self):
+        """Checks whether files in sub directories are deleted."""
+        with tempfile.TemporaryDirectory() as dir_a, \
+                tempfile.NamedTemporaryFile(dir=dir_a, delete=False), \
+                tempfile.TemporaryDirectory(dir=dir_a) as dir_a_b, \
+                tempfile.NamedTemporaryFile(dir=dir_a_b) as file_a_b1:
+            self.assertEqual(len(os.listdir(dir_a)), 2)
+            self.assertEqual(len(os.listdir(dir_a_b)), 1)
+            delete_all_files_in_dir(dir_a)
+            self.assertEqual(os.listdir(dir_a), [os.path.basename(dir_a_b)])
+            self.assertEqual(os.listdir(dir_a_b), [os.path.basename(file_a_b1.name)])