refactor image cache

crates/common/src/caching.rs

@@ -0,0 +1,135 @@
+use std::collections::{HashMap, VecDeque};
+use std::mem::take;
+
+use futures::FutureExt;
+use gpui::{
+    App, AppContext, Asset, AssetLogger, ElementId, Entity, ImageAssetLoader, ImageCache,
+    ImageCacheItem, ImageCacheProvider, ImageSource, Resource, hash,
+};
+
+pub fn coop_cache(id: impl Into<ElementId>, max_items: usize) -> CoopImageCacheProvider {
+    CoopImageCacheProvider {
+        id: id.into(),
+        max_items,
+    }
+}
+
+pub struct CoopImageCacheProvider {
+    id: ElementId,
+    max_items: usize,
+}
+
+impl ImageCacheProvider for CoopImageCacheProvider {
+    fn provide(&mut self, window: &mut gpui::Window, cx: &mut App) -> gpui::AnyImageCache {
+        window
+            .with_global_id(self.id.clone(), |id, window| {
+                window.with_element_state(id, |cache, _| {
+                    let cache = cache.unwrap_or_else(|| CoopImageCache::new(self.max_items, cx));
+                    (cache.clone(), cache)
+                })
+            })
+            .into()
+    }
+}
+
+pub struct CoopImageCache {
+    max_items: usize,
+    usage_list: VecDeque<u64>,
+    cache: HashMap<u64, (ImageCacheItem, Resource)>,
+}
+
+impl CoopImageCache {
+    pub fn new(max_items: usize, cx: &mut App) -> Entity<Self> {
+        cx.new(|cx| {
+            log::info!("Creating CoopImageCache");
+            cx.on_release(|this: &mut Self, cx| {
+                for (ix, (mut image, resource)) in take(&mut this.cache) {
+                    if let Some(Ok(image)) = image.get() {
+                        log::info!("Dropping image {ix}");
+                        cx.drop_image(image, None);
+                    }
+                    ImageSource::Resource(resource).remove_asset(cx);
+                }
+            })
+            .detach();
+
+            CoopImageCache {
+                max_items,
+                usage_list: VecDeque::with_capacity(max_items),
+                cache: HashMap::with_capacity(max_items),
+            }
+        })
+    }
+}
+
+impl ImageCache for CoopImageCache {
+    fn load(
+        &mut self,
+        resource: &Resource,
+        window: &mut gpui::Window,
+        cx: &mut gpui::App,
+    ) -> Option<Result<std::sync::Arc<gpui::RenderImage>, gpui::ImageCacheError>> {
+        let hash = hash(resource);
+
+        if let Some(item) = self.cache.get_mut(&hash) {
+            let current_idx = self
+                .usage_list
+                .iter()
+                .position(|item| *item == hash)
+                .expect("cache has an item usage_list doesn't");
+
+            self.usage_list.remove(current_idx);
+            self.usage_list.push_front(hash);
+
+            return item.0.get();
+        }
+
+        let load_future = AssetLogger::<ImageAssetLoader>::load(resource.clone(), cx);
+        let task = cx.background_executor().spawn(load_future).shared();
+
+        if self.usage_list.len() >= self.max_items {
+            log::info!("Image cache is full, evicting oldest item");
+
+            if let Some(oldest) = self.usage_list.pop_back() {
+                let mut image = self
+                    .cache
+                    .remove(&oldest)
+                    .expect("usage_list has an item cache doesn't");
+
+                if let Some(Ok(image)) = image.0.get() {
+                    log::info!("requesting image to be dropped");
+                    cx.drop_image(image, Some(window));
+                }
+
+                ImageSource::Resource(image.1).remove_asset(cx);
+            }
+        }
+
+        self.cache.insert(
+            hash,
+            (
+                gpui::ImageCacheItem::Loading(task.clone()),
+                resource.clone(),
+            ),
+        );
+        self.usage_list.push_front(hash);
+
+        let entity = window.current_view();
+
+        window
+            .spawn(cx, async move |cx| {
+                let result = task.await;
+
+                if let Err(err) = result {
+                    log::error!("error loading image into cache: {:?}", err);
+                }
+
+                cx.on_next_frame(move |_, cx| {
+                    cx.notify(entity);
+                });
+            })
+            .detach();
+
+        None
+    }
+}