[pitivi] previewers: Integrate the master cache in the ThumbnailCache class

[Alexandru Băluț <alexbalut src gnome org>]

commit 9d1d846b056d2cf1e0cc292175b6bda22cf6d7aa
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Wed Oct 5 13:07:37 2016 +0200

    previewers: Integrate the master cache in the ThumbnailCache class
    
    Reviewed-by: Thibault Saunier <tsaunier gnome org>
    Differential Revision: https://phabricator.freedesktop.org/D1350

 pitivi/medialibrary.py        |    4 +-
 pitivi/timeline/previewers.py |   62 ++++++++++++++++++++---------------------
 tests/test_previewers.py      |   22 +++++++++++++-
 3 files changed, 52 insertions(+), 36 deletions(-)
---
diff --git a/pitivi/medialibrary.py b/pitivi/medialibrary.py
index a66922d..7137d51 100644
--- a/pitivi/medialibrary.py
+++ b/pitivi/medialibrary.py
@@ -45,7 +45,7 @@ from pitivi.dialogs.clipmediaprops import ClipMediaPropsDialog
 from pitivi.dialogs.filelisterrordialog import FileListErrorDialog
 from pitivi.mediafilespreviewer import PreviewWidget
 from pitivi.settings import GlobalSettings
-from pitivi.timeline.previewers import getThumbnailCache
+from pitivi.timeline.previewers import ThumbnailCache
 from pitivi.utils.loggable import Loggable
 from pitivi.utils.misc import disconnectAllByFunc
 from pitivi.utils.misc import get_proxy_target
@@ -792,7 +792,7 @@ class MediaLibraryWidget(Gtk.Box, Loggable):
                     thumb_128 = self._getIcon(
                         "image-x-generic", None, LARGE_SIZE)
                 else:
-                    thumb_cache = getThumbnailCache(asset)
+                    thumb_cache = ThumbnailCache.get(asset)
                     thumb_64 = thumb_cache.getPreviewThumbnail()
                     if not thumb_64:
                         thumb_64 = self._getIcon("video-x-generic")
diff --git a/pitivi/timeline/previewers.py b/pitivi/timeline/previewers.py
index 1fe8ea9..0c43a0f 100644
--- a/pitivi/timeline/previewers.py
+++ b/pitivi/timeline/previewers.py
@@ -141,7 +141,7 @@ class ThumbnailBin(PreviewerBin):
     def do_set_property(self, prop, value):
         if prop.name == 'uri':
             self.uri = value
-            self.thumb_cache = getThumbnailCache(value)
+            self.thumb_cache = ThumbnailCache.get(self.uri)
         else:
             raise AttributeError('unknown property %s' % prop.name)
 
@@ -387,7 +387,7 @@ class VideoPreviewer(Previewer, Zoomable, Loggable):
 
         # Maps (quantized) times to Thumbnail objects
         self.thumbs = {}
-        self.thumb_cache = getThumbnailCache(self.uri)
+        self.thumb_cache = ThumbnailCache.get(self.uri)
         self.thumb_width, unused_height = self.thumb_cache.getImagesSize()
 
         self.cpu_usage_tracker = CPUUsageTracker()
@@ -720,40 +720,16 @@ class Thumbnail(Gtk.Image):
         self.props.width_request = self.width
         self.props.height_request = self.height
 
-CACHES = {}
-
-
-# pylint: disable=invalid-name
-def getThumbnailCache(obj):
-    """Gets a ThumbnailCache for the specified object.
-
-    Args:
-        obj (str or GES.UriClipAsset): The object for which to get a cache,
-            it can be a string ora GES.UriClipAsset
-
-    Returns:
-        ThumbnailCache: The cache for the object.
-    """
-    if isinstance(obj, str):
-        uri = obj
-    elif isinstance(obj, GES.UriClipAsset):
-        uri = get_proxy_target(obj).props.id
-
-    if uri in CACHES:
-        return CACHES[uri]
-    else:
-        cache = ThumbnailCache(uri)
-        CACHES[uri] = cache
-        return cache
-
 
 class ThumbnailCache(Loggable):
-    """Caches thumbnails by key using LRU policy.
+    """Caches an asset's thumbnails by key, using LRU policy.
 
     Uses a two stage caching mechanism. A limited number of elements are
     held in memory, the rest is being cached on disk in an SQLite db.
     """
 
+    caches_by_uri = {}
+
     def __init__(self, uri):
         Loggable.__init__(self)
         self._filehash = hash_file(Gst.uri_get_location(uri))
@@ -766,6 +742,28 @@ class ThumbnailCache(Loggable):
                           (Time INTEGER NOT NULL PRIMARY KEY,\
                           Jpeg BLOB NOT NULL)")
 
+    @classmethod
+    def get(cls, obj):
+        """Gets a ThumbnailCache for the specified object.
+
+        Args:
+            obj (str or GES.UriClipAsset): The object for which to get a cache,
+                it can be a string representing a URI, or a GES.UriClipAsset.
+
+        Returns:
+            ThumbnailCache: The cache for the object.
+        """
+        if isinstance(obj, str):
+            uri = obj
+        elif isinstance(obj, GES.UriClipAsset):
+            uri = get_proxy_target(obj).props.id
+        else:
+            raise ValueError("Unhandled type: %s" % type(obj))
+
+        if uri not in cls.caches_by_uri:
+            cls.caches_by_uri[uri] = ThumbnailCache(uri)
+        return cls.caches_by_uri[uri]
+
     def copy(self, uri):
         """Copies `self` to the specified `uri`.
 
@@ -863,7 +861,7 @@ class PipelineCpuAdapter(Loggable):
         self.rate = 1.0
         self.done = False
         self.ready = False
-        self.lastPos = 0
+        self.last_pos = 0
         self._bus_cb_id = None
 
     def start(self):
@@ -896,7 +894,7 @@ class PipelineCpuAdapter(Loggable):
                     res, position = self.pipeline.query_position(
                         Gst.Format.TIME)
                     if res:
-                        self.lastPos = position
+                        self.last_pos = position
                     self.pipeline.set_state(Gst.State.READY)
                     self.ready = True
                 return True
@@ -943,7 +941,7 @@ class PipelineCpuAdapter(Loggable):
                                        Gst.Format.TIME,
                                        Gst.SeekFlags.FLUSH | Gst.SeekFlags.ACCURATE,
                                        Gst.SeekType.SET,
-                                       self.lastPos,
+                                       self.last_pos,
                                        Gst.SeekType.NONE,
                                        -1)
                     self.ready = False
diff --git a/tests/test_previewers.py b/tests/test_previewers.py
index 4afeeaf..7c3a1c7 100644
--- a/tests/test_previewers.py
+++ b/tests/test_previewers.py
@@ -18,14 +18,16 @@
 # Boston, MA 02110-1301, USA.
 import os
 import pickle
+import tempfile
 from unittest import mock
+from unittest import TestCase
 
 from gi.repository import GES
 from gi.repository import Gst
 
 from pitivi.timeline.previewers import get_wavefile_location_for_uri
-from pitivi.timeline.previewers import getThumbnailCache
 from pitivi.timeline.previewers import THUMB_HEIGHT
+from pitivi.timeline.previewers import ThumbnailCache
 from tests import common
 from tests.test_media_library import BaseTestMediaLibrary
 
@@ -46,7 +48,7 @@ class TestPreviewers(BaseTestMediaLibrary):
         sample_uri = common.get_sample_uri(sample_name)
         asset = GES.UriClipAsset.request_sync(sample_uri)
 
-        thumb_cache = getThumbnailCache(asset)
+        thumb_cache = ThumbnailCache.get(asset)
         width, height = thumb_cache.getImagesSize()
         self.assertEqual(height, THUMB_HEIGHT)
         self.assertTrue(thumb_cache[0] is not None)
@@ -59,3 +61,19 @@ class TestPreviewers(BaseTestMediaLibrary):
             samples = pickle.load(fsamples)
 
         self.assertTrue(bool(samples))
+
+
+class TestThumbnailCache(TestCase):
+
+    def test_get(self):
+        with self.assertRaises(ValueError):
+            ThumbnailCache.get(1)
+        with mock.patch("pitivi.timeline.previewers.xdg_cache_home") as xdg_config_home,\
+                tempfile.TemporaryDirectory() as temp_dir:
+            xdg_config_home.return_value = temp_dir
+            sample_uri = common.get_sample_uri("1sec_simpsons_trailer.mp4")
+            cache = ThumbnailCache.get(sample_uri)
+            self.assertIsNotNone(cache)
+
+            asset = GES.UriClipAsset.request_sync(sample_uri)
+            self.assertEqual(ThumbnailCache.get(asset), cache)