use lazy caching texture list to limit number of images loaded at one time

1 files changed, 126 insertions, 0 deletions

diff --git a/lazycachelist.py b/lazycachelist.py
new file mode 100644
index 0000000..0c37ba3
--- /dev/null
+++ b/lazycachelist.py
@@ -0,0 +1,126 @@
+from dataclasses import dataclass
+
+from texture import ImageTextureImmichAsset
+
+@dataclass
+class Album:
+    id: str
+    range_start: int
+    range_end: int
+    assets_list: list[str] = None
+
+    @property
+    def assets_count(self):
+        return end - start
+
+
+class LazyCachingTextureList():
+    def __init__(self, immich_connector, album_ids, max_cache_items=100):
+        self.immich_connector = immich_connector
+        assert max_cache_items >= 20, "Minimum cache items is 20"  # Double small radius
+
+        # Ring buffer
+        self.cache_length = max_cache_items
+        self.cache = [None] * max_cache_items
+        self.radius_small = 10
+        self.radius_large = int(max_cache_items / 2)
+        self.cache_items_behind = 0
+        self.cache_items_ahead = 0
+        self.cache_index = 0
+        self.asset_index = 0
+        self.asset_count = 0
+
+        self.cached_items = 0
+
+        self.album_keys = album_ids
+        self.albums = self._get_albums()
+
+    def index_in_cache_range(self, index):
+        index_range_low  = (self.asset_index - self.cache_items_behind) % self.asset_count
+        index_range_high = (self.asset_index + self.cache_items_ahead ) % self.asset_count
+        if index_range_low > index_range_high:
+            return index_range_low <= index or index <= index_range_high
+        return index_range_low <= index <= index_range_high
+
+    def _get_albums(self):
+        albums = []
+        self.asset_count = i = 0
+        albums_info = self.immich_connector.load_all_albums()
+        for album_info in albums_info:
+            id = album_info["id"]
+            if id not in self.album_keys:
+                continue
+            asset_count = album_info["assetCount"]
+            albums.append(Album(id, i, i + asset_count))
+            i += asset_count + 1
+            self.asset_count += asset_count
+        #self.asset_count = sum(( album.assets_count for album in self.albums ))
+        return albums
+
+    def _get_album_asset_by_index(self, asset_index):
+        if asset_index < 0:
+            asset_index = asset_count - asset_index
+        for album in self.albums:
+            if album.range_start <= asset_index <= album.range_end:
+                if album.assets_list is None:
+                    album.assets_list = self.immich_connector.load_album_assets(album.id)
+                return album.assets_list[asset_index - album.range_start]
+        raise IndexError("Index out of bounds")
+
+    def _fill_cache(self, current_radius, final_radius, step):
+        if current_radius >= final_radius:
+            return current_radius
+
+        for i in range(current_radius * step, final_radius * step, step):
+            cache_index = (self.cache_index + i) % self.cache_length
+            asset_index = (self.asset_index + i) % self.asset_count
+            if self.cache[cache_index]:
+                self.cache[cache_index].free()  # Since this is a ring buffer, textures outside of range can just get free'd here
+            asset = self._get_album_asset_by_index(asset_index)
+            tex = ImageTextureImmichAsset(asset, asset_index)
+            self.immich_connector.load_texture_async(self, tex)
+            self.cache[cache_index] = tex
+            self.cached_items += 1
+
+        return max(current_radius, final_radius)
+
+    def _update_cache_get_item(self, asset_index):
+        prev_asset_index = self.asset_index
+        self.asset_index = asset_index % self.asset_count
+        # Movement is the distance between the previous and current index in the assets list
+        # Since the list wraps around, fastest method is just to get the abs min of the 3 cases
+        movement = min(
+            asset_index - prev_asset_index,       # No list wrap
+            asset_index - self.asset_count,       # Wrap backwards (0  -> -1)
+            self.asset_count - prev_asset_index,  # Wrap forwards  (-1 ->  0)
+        key=abs)
+        self.cache_index = (self.cache_index + movement) % self.cache_length
+
+        ahead  = max(0, self.cache_items_ahead  - movement)
+        behind = max(0, self.cache_items_behind + movement)
+
+        if ahead + behind > self.cache_length:
+            if movement < 0:
+                ahead += movement
+            else:
+                behind -= movement
+
+        #print("AHEAD/BEHIND/CACHE_I/ASSET_I/MOVEMENT:", ahead, behind, self.cache_index, self.asset_index, movement)
+        # TODO if ahead is 0 then clear queue
+
+        ahead  = self._fill_cache(ahead,  self.radius_small, +1)  # Fill small radius ahead of cache_index
+        behind = self._fill_cache(behind, self.radius_small, -1)  # Fill small radius behind cache_index
+        ahead  = self._fill_cache(ahead,  self.radius_large, +1)  # Fill large radius ahead of cache_index
+
+        self.cache_items_ahead = ahead
+        self.cache_items_behind = behind
+        return self.cache[self.cache_index]
+
+    def __len__(self):
+        return self.asset_count
+
+    def __getitem__(self, index):
+        i = index % self.asset_count
+        if abs(index) > i:
+            raise IndexError("Index out of bounds")
+        return self._update_cache_get_item(index)