Make image cache per-document rather than global

1 files changed, 0 insertions, 645 deletions

diff --git a/components/net/image_cache_thread.rs b/components/net/image_cache_thread.rs
deleted file mode 100644
index a9cdca099d7..00000000000
--- a/components/net/image_cache_thread.rs
+++ /dev/null
@@ -1,645 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-use immeta::load_from_buf;
-use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
-use ipc_channel::router::ROUTER;
-use net_traits::{NetworkError, FetchResponseMsg};
-use net_traits::image::base::{Image, ImageMetadata, PixelFormat, load_from_memory};
-use net_traits::image_cache_thread::{ImageCacheCommand, ImageCacheThread, ImageState};
-use net_traits::image_cache_thread::{ImageOrMetadataAvailable, ImageResponse, UsePlaceholder};
-use net_traits::image_cache_thread::{ImageResponder, PendingImageId, CanRequestImages};
-use servo_config::resource_files::resources_dir_path;
-use servo_url::ServoUrl;
-use std::borrow::ToOwned;
-use std::collections::HashMap;
-use std::collections::hash_map::Entry::{Occupied, Vacant};
-use std::fs::File;
-use std::io::{self, Read};
-use std::mem;
-use std::sync::Arc;
-use std::sync::mpsc::{Receiver, Sender, channel};
-use std::thread;
-use threadpool::ThreadPool;
-use webrender_traits;
-
-///
-/// TODO(gw): Remaining work on image cache:
-///     * Make use of the prefetch support in various parts of the code.
-///     * Profile time in GetImageIfAvailable - might be worth caching these results per paint / layout thread.
-///
-/// MAYBE(Yoric):
-///     * For faster lookups, it might be useful to store the LoadKey in the DOM once we have performed a first load.
-
-// TODO(gw): This is a port of the old is_image_opaque code from WR.
-//           Consider using SIMD to speed this up if it shows in profiles.
-fn is_image_opaque(format: webrender_traits::ImageFormat, bytes: &[u8]) -> bool {
-    match format {
-        webrender_traits::ImageFormat::RGBA8 => {
-            let mut is_opaque = true;
-            for i in 0..(bytes.len() / 4) {
-                if bytes[i * 4 + 3] != 255 {
-                    is_opaque = false;
-                    break;
-                }
-            }
-            is_opaque
-        }
-        webrender_traits::ImageFormat::RGB8 => true,
-        webrender_traits::ImageFormat::A8 => false,
-        webrender_traits::ImageFormat::Invalid | webrender_traits::ImageFormat::RGBAF32 => unreachable!(),
-    }
-}
-
-/// Represents an image that is either being loaded
-/// by the resource thread, or decoded by a worker thread.
-struct PendingLoad {
-    // The bytes loaded so far. Reset to an empty vector once loading
-    // is complete and the buffer has been transmitted to the decoder.
-    bytes: ImageBytes,
-
-    // Image metadata, if available.
-    metadata: Option<ImageMetadata>,
-
-    // Once loading is complete, the result of the operation.
-    result: Option<Result<(), NetworkError>>,
-    listeners: Vec<ImageResponder>,
-
-    // The url being loaded. Do not forget that this may be several Mb
-    // if we are loading a data: url.
-    url: ServoUrl,
-}
-
-enum ImageBytes {
-    InProgress(Vec<u8>),
-    Complete(Arc<Vec<u8>>),
-}
-
-impl ImageBytes {
-    fn extend_from_slice(&mut self, data: &[u8]) {
-        match *self {
-            ImageBytes::InProgress(ref mut bytes) => bytes.extend_from_slice(data),
-            ImageBytes::Complete(_) => panic!("attempted modification of complete image bytes"),
-        }
-    }
-
-    fn mark_complete(&mut self) -> Arc<Vec<u8>> {
-        let bytes = {
-            let own_bytes = match *self {
-                ImageBytes::InProgress(ref mut bytes) => bytes,
-                ImageBytes::Complete(_) => panic!("attempted modification of complete image bytes"),
-            };
-            mem::replace(own_bytes, vec![])
-        };
-        let bytes = Arc::new(bytes);
-        *self = ImageBytes::Complete(bytes.clone());
-        bytes
-    }
-
-    fn as_slice(&self) -> &[u8] {
-        match *self {
-            ImageBytes::InProgress(ref bytes) => &bytes,
-            ImageBytes::Complete(ref bytes) => &*bytes,
-        }
-    }
-}
-
-enum LoadResult {
-    Loaded(Image),
-    PlaceholderLoaded(Arc<Image>),
-    None
-}
-
-impl PendingLoad {
-    fn new(url: ServoUrl) -> PendingLoad {
-        PendingLoad {
-            bytes: ImageBytes::InProgress(vec!()),
-            metadata: None,
-            result: None,
-            listeners: vec!(),
-            url: url,
-        }
-    }
-
-    fn add_listener(&mut self, listener: ImageResponder) {
-        self.listeners.push(listener);
-    }
-}
-
-// Represents all the currently pending loads/decodings. For
-// performance reasons, loads are indexed by a dedicated load key.
-struct AllPendingLoads {
-    // The loads, indexed by a load key. Used during most operations,
-    // for performance reasons.
-    loads: HashMap<LoadKey, PendingLoad>,
-
-    // Get a load key from its url. Used ony when starting and
-    // finishing a load or when adding a new listener.
-    url_to_load_key: HashMap<ServoUrl, LoadKey>,
-
-    // A counter used to generate instances of LoadKey
-    keygen: LoadKeyGenerator,
-}
-
-/// Result of accessing a cache.
-enum CacheResult<'a> {
-    /// The value was in the cache.
-    Hit(LoadKey, &'a mut PendingLoad),
-    /// The value was not in the cache and needed to be regenerated.
-    Miss(Option<(LoadKey, &'a mut PendingLoad)>),
-}
-
-impl AllPendingLoads {
-    fn new() -> AllPendingLoads {
-        AllPendingLoads {
-            loads: HashMap::new(),
-            url_to_load_key: HashMap::new(),
-            keygen: LoadKeyGenerator::new(),
-        }
-    }
-
-    // `true` if there is no currently pending load, `false` otherwise.
-    fn is_empty(&self) -> bool {
-        assert!(self.loads.is_empty() == self.url_to_load_key.is_empty());
-        self.loads.is_empty()
-    }
-
-    // get a PendingLoad from its LoadKey.
-    fn get_by_key_mut(&mut self, key: &LoadKey) -> Option<&mut PendingLoad> {
-        self.loads.get_mut(key)
-    }
-
-    fn remove(&mut self, key: &LoadKey) -> Option<PendingLoad> {
-        self.loads.remove(key).
-            and_then(|pending_load| {
-                self.url_to_load_key.remove(&pending_load.url).unwrap();
-                Some(pending_load)
-            })
-    }
-
-    fn get_cached<'a>(&'a mut self, url: ServoUrl, can_request: CanRequestImages)
-                      -> CacheResult<'a> {
-        match self.url_to_load_key.entry(url.clone()) {
-            Occupied(url_entry) => {
-                let load_key = url_entry.get();
-                CacheResult::Hit(*load_key, self.loads.get_mut(load_key).unwrap())
-            }
-            Vacant(url_entry) => {
-                if can_request == CanRequestImages::No {
-                    return CacheResult::Miss(None);
-                }
-
-                let load_key = self.keygen.next();
-                url_entry.insert(load_key);
-
-                let pending_load = PendingLoad::new(url);
-                match self.loads.entry(load_key) {
-                    Occupied(_) => unreachable!(),
-                    Vacant(load_entry) => {
-                        let mut_load = load_entry.insert(pending_load);
-                        CacheResult::Miss(Some((load_key, mut_load)))
-                    }
-                }
-            }
-        }
-    }
-}
-
-/// Represents an image that has completed loading.
-/// Images that fail to load (due to network or decode
-/// failure) are still stored here, so that they aren't
-/// fetched again.
-struct CompletedLoad {
-    image_response: ImageResponse,
-    id: PendingImageId,
-}
-
-impl CompletedLoad {
-    fn new(image_response: ImageResponse, id: PendingImageId) -> CompletedLoad {
-        CompletedLoad {
-            image_response: image_response,
-            id: id,
-        }
-    }
-}
-
-// A key used to communicate during loading.
-type LoadKey = PendingImageId;
-
-struct LoadKeyGenerator {
-    counter: u64
-}
-
-impl LoadKeyGenerator {
-    fn new() -> LoadKeyGenerator {
-        LoadKeyGenerator {
-            counter: 0
-        }
-    }
-    fn next(&mut self) -> PendingImageId {
-        self.counter += 1;
-        PendingImageId(self.counter)
-    }
-}
-
-struct ResourceLoadInfo {
-    action: FetchResponseMsg,
-    key: LoadKey,
-}
-
-/// Implementation of the image cache
-struct ImageCache {
-    decoder_sender: Sender<DecoderMsg>,
-
-    // Worker threads for decoding images.
-    thread_pool: ThreadPool,
-
-    // Images that are loading over network, or decoding.
-    pending_loads: AllPendingLoads,
-
-    // Images that have finished loading (successful or not)
-    completed_loads: HashMap<ServoUrl, CompletedLoad>,
-
-    // The placeholder image used when an image fails to load
-    placeholder_image: Option<Arc<Image>>,
-
-    // Webrender API instance.
-    webrender_api: webrender_traits::RenderApi,
-}
-
-/// Message that the decoder worker threads send to main image cache thread.
-struct DecoderMsg {
-    key: LoadKey,
-    image: Option<Image>,
-}
-
-struct Receivers {
-    cmd_receiver: Receiver<ImageCacheCommand>,
-    decoder_receiver: Receiver<DecoderMsg>,
-}
-
-impl Receivers {
-    #[allow(unsafe_code)]
-    fn recv(&self) -> SelectResult {
-        let cmd_receiver = &self.cmd_receiver;
-        let decoder_receiver = &self.decoder_receiver;
-        select! {
-            msg = cmd_receiver.recv() => {
-                SelectResult::Command(msg.unwrap())
-            },
-            msg = decoder_receiver.recv() => {
-                SelectResult::Decoder(msg.unwrap())
-            }
-        }
-    }
-}
-
-/// The types of messages that the main image cache thread receives.
-enum SelectResult {
-    Command(ImageCacheCommand),
-    Decoder(DecoderMsg),
-}
-
-fn convert_format(format: PixelFormat) -> webrender_traits::ImageFormat {
-    match format {
-        PixelFormat::K8 | PixelFormat::KA8 => {
-            panic!("Not support by webrender yet");
-        }
-        PixelFormat::RGB8 => webrender_traits::ImageFormat::RGB8,
-        PixelFormat::RGBA8 => webrender_traits::ImageFormat::RGBA8,
-    }
-}
-
-fn get_placeholder_image(webrender_api: &webrender_traits::RenderApi) -> io::Result<Arc<Image>> {
-    let mut placeholder_path = try!(resources_dir_path());
-    placeholder_path.push("rippy.png");
-    let mut file = try!(File::open(&placeholder_path));
-    let mut image_data = vec![];
-    try!(file.read_to_end(&mut image_data));
-    let mut image = load_from_memory(&image_data).unwrap();
-    let format = convert_format(image.format);
-    let mut bytes = Vec::new();
-    bytes.extend_from_slice(&*image.bytes);
-    let descriptor = webrender_traits::ImageDescriptor {
-        width: image.width,
-        height: image.height,
-        stride: None,
-        format: format,
-        offset: 0,
-        is_opaque: is_image_opaque(format, &bytes),
-    };
-    let data = webrender_traits::ImageData::new(bytes);
-    let image_key = webrender_api.generate_image_key();
-    webrender_api.add_image(image_key, descriptor, data, None);
-    image.id = Some(image_key);
-    Ok(Arc::new(image))
-}
-
-fn premultiply(data: &mut [u8]) {
-    let length = data.len();
-
-    for i in (0..length).step_by(4) {
-        let b = data[i + 0] as u32;
-        let g = data[i + 1] as u32;
-        let r = data[i + 2] as u32;
-        let a = data[i + 3] as u32;
-
-        data[i + 0] = (b * a / 255) as u8;
-        data[i + 1] = (g * a / 255) as u8;
-        data[i + 2] = (r * a / 255) as u8;
-    }
-}
-
-impl ImageCache {
-    fn run(webrender_api: webrender_traits::RenderApi,
-           ipc_command_receiver: IpcReceiver<ImageCacheCommand>) {
-        // Preload the placeholder image, used when images fail to load.
-        let placeholder_image = get_placeholder_image(&webrender_api).ok();
-
-        // Ask the router to proxy messages received over IPC to us.
-        let cmd_receiver = ROUTER.route_ipc_receiver_to_new_mpsc_receiver(ipc_command_receiver);
-
-        let (decoder_sender, decoder_receiver) = channel();
-        let mut cache = ImageCache {
-            decoder_sender: decoder_sender,
-            thread_pool: ThreadPool::new(4),
-            pending_loads: AllPendingLoads::new(),
-            completed_loads: HashMap::new(),
-            placeholder_image: placeholder_image,
-            webrender_api: webrender_api,
-        };
-
-        let receivers = Receivers {
-            cmd_receiver: cmd_receiver,
-            decoder_receiver: decoder_receiver,
-        };
-
-        let mut exit_sender: Option<IpcSender<()>> = None;
-
-        loop {
-            match receivers.recv() {
-                SelectResult::Command(cmd) => {
-                    exit_sender = cache.handle_cmd(cmd);
-                }
-                SelectResult::Decoder(msg) => {
-                    cache.handle_decoder(msg);
-                }
-            }
-
-            // Can only exit when all pending loads are complete.
-            if let Some(ref exit_sender) = exit_sender {
-                if cache.pending_loads.is_empty() {
-                    exit_sender.send(()).unwrap();
-                    break;
-                }
-            }
-        }
-    }
-
-    // Handle a request from a client
-    fn handle_cmd(&mut self, cmd: ImageCacheCommand) -> Option<IpcSender<()>> {
-        match cmd {
-            ImageCacheCommand::Exit(sender) => {
-                return Some(sender);
-            }
-            ImageCacheCommand::AddListener(id, responder) => {
-                self.add_listener(id, responder);
-            }
-            ImageCacheCommand::GetImageOrMetadataIfAvailable(url,
-                                                             use_placeholder,
-                                                             can_request,
-                                                             consumer) => {
-                let result = self.get_image_or_meta_if_available(url, use_placeholder, can_request);
-                // TODO(#15501): look for opportunities to clean up cache if this send fails.
-                let _ = consumer.send(result);
-            }
-            ImageCacheCommand::StoreDecodeImage(id, data) => {
-                self.handle_progress(ResourceLoadInfo {
-                    action: data,
-                    key: id
-                });
-            }
-        };
-
-        None
-    }
-
-    // Handle progress messages from the resource thread
-    fn handle_progress(&mut self, msg: ResourceLoadInfo) {
-        match (msg.action, msg.key) {
-            (FetchResponseMsg::ProcessRequestBody, _) |
-            (FetchResponseMsg::ProcessRequestEOF, _) => return,
-            (FetchResponseMsg::ProcessResponse(_response), _) => {}
-            (FetchResponseMsg::ProcessResponseChunk(data), _) => {
-                debug!("got some data for {:?}", msg.key);
-                let pending_load = self.pending_loads.get_by_key_mut(&msg.key).unwrap();
-                pending_load.bytes.extend_from_slice(&data);
-                //jmr0 TODO: possibly move to another task?
-                if let None = pending_load.metadata {
-                    if let Ok(metadata) = load_from_buf(&pending_load.bytes.as_slice()) {
-                        let dimensions = metadata.dimensions();
-                        let img_metadata = ImageMetadata { width: dimensions.width,
-                                                           height: dimensions.height };
-                        for listener in &pending_load.listeners {
-                            listener.respond(ImageResponse::MetadataLoaded(img_metadata.clone()));
-                        }
-                        pending_load.metadata = Some(img_metadata);
-                    }
-                }
-            }
-            (FetchResponseMsg::ProcessResponseEOF(result), key) => {
-                debug!("received EOF for {:?}", key);
-                match result {
-                    Ok(()) => {
-                        let pending_load = self.pending_loads.get_by_key_mut(&msg.key).unwrap();
-                        pending_load.result = Some(result);
-                        let bytes = pending_load.bytes.mark_complete();
-                        let sender = self.decoder_sender.clone();
-                        debug!("async decoding {} ({:?})", pending_load.url, key);
-
-                        self.thread_pool.execute(move || {
-                            let msg = decode_bytes_sync(key, &*bytes);
-                            sender.send(msg).unwrap();
-                        });
-                    }
-                    Err(_) => {
-                        debug!("processing error for {:?}", key);
-                        match self.placeholder_image.clone() {
-                            Some(placeholder_image) => {
-                                self.complete_load(msg.key, LoadResult::PlaceholderLoaded(
-                                        placeholder_image))
-                            }
-                            None => self.complete_load(msg.key, LoadResult::None),
-                        }
-                    }
-                }
-            }
-        }
-    }
-
-    // Handle a message from one of the decoder worker threads
-    fn handle_decoder(&mut self, msg: DecoderMsg) {
-        let image = match msg.image {
-            None => LoadResult::None,
-            Some(image) => LoadResult::Loaded(image),
-        };
-        self.complete_load(msg.key, image);
-    }
-
-    // Change state of a url from pending -> loaded.
-    fn complete_load(&mut self, key: LoadKey, mut load_result: LoadResult) {
-        let pending_load = match self.pending_loads.remove(&key) {
-            Some(load) => load,
-            None => return,
-        };
-
-        match load_result {
-            LoadResult::Loaded(ref mut image) => {
-                let format = convert_format(image.format);
-                let mut bytes = Vec::new();
-                bytes.extend_from_slice(&*image.bytes);
-                if format == webrender_traits::ImageFormat::RGBA8 {
-                    premultiply(bytes.as_mut_slice());
-                }
-                let descriptor = webrender_traits::ImageDescriptor {
-                    width: image.width,
-                    height: image.height,
-                    stride: None,
-                    format: format,
-                    offset: 0,
-                    is_opaque: is_image_opaque(format, &bytes),
-                };
-                let data = webrender_traits::ImageData::new(bytes);
-                let image_key = self.webrender_api.generate_image_key();
-                self.webrender_api.add_image(image_key, descriptor, data, None);
-                image.id = Some(image_key);
-            }
-            LoadResult::PlaceholderLoaded(..) | LoadResult::None => {}
-        }
-
-        let image_response = match load_result {
-            LoadResult::Loaded(image) => ImageResponse::Loaded(Arc::new(image)),
-            LoadResult::PlaceholderLoaded(image) => ImageResponse::PlaceholderLoaded(image),
-            LoadResult::None => ImageResponse::None,
-        };
-
-        let completed_load = CompletedLoad::new(image_response.clone(), key);
-        self.completed_loads.insert(pending_load.url.into(), completed_load);
-
-        for listener in pending_load.listeners {
-            listener.respond(image_response.clone());
-        }
-    }
-
-    /// Add a listener for a given image if it is still pending, or notify the
-    /// listener if the image is complete.
-    fn add_listener(&mut self,
-                    id: PendingImageId,
-                    listener: ImageResponder) {
-        if let Some(load) = self.pending_loads.get_by_key_mut(&id) {
-            if let Some(ref metadata) = load.metadata {
-                listener.respond(ImageResponse::MetadataLoaded(metadata.clone()));
-            }
-            load.add_listener(listener);
-            return;
-        }
-        if let Some(load) = self.completed_loads.values().find(|l| l.id == id) {
-            listener.respond(load.image_response.clone());
-            return;
-        }
-        warn!("Couldn't find cached entry for listener {:?}", id);
-    }
-
-    /// Return a completed image if it exists, or None if there is no complete load
-    /// or the complete load is not fully decoded or is unavailable.
-    fn get_completed_image_if_available(&self,
-                                        url: &ServoUrl,
-                                        placeholder: UsePlaceholder)
-                                        -> Option<Result<ImageOrMetadataAvailable, ImageState>> {
-        self.completed_loads.get(url).map(|completed_load| {
-            match (&completed_load.image_response, placeholder) {
-                (&ImageResponse::Loaded(ref image), _) |
-                (&ImageResponse::PlaceholderLoaded(ref image), UsePlaceholder::Yes) => {
-                    Ok(ImageOrMetadataAvailable::ImageAvailable(image.clone()))
-                }
-                (&ImageResponse::PlaceholderLoaded(_), UsePlaceholder::No) |
-                (&ImageResponse::None, _) |
-                (&ImageResponse::MetadataLoaded(_), _) => {
-                    Err(ImageState::LoadError)
-                }
-            }
-        })
-    }
-
-    /// Return any available metadata or image for the given URL, or an indication that
-    /// the image is not yet available if it is in progress, or else reserve a slot in
-    /// the cache for the URL if the consumer can request images.
-    fn get_image_or_meta_if_available(&mut self,
-                                      url: ServoUrl,
-                                      placeholder: UsePlaceholder,
-                                      can_request: CanRequestImages)
-                                      -> Result<ImageOrMetadataAvailable, ImageState> {
-        if let Some(result) = self.get_completed_image_if_available(&url, placeholder) {
-            debug!("{} is available", url);
-            return result;
-        }
-
-        let decoded = {
-            let result = self.pending_loads.get_cached(url.clone(), can_request);
-            match result {
-                CacheResult::Hit(key, pl) => match (&pl.result, &pl.metadata) {
-                    (&Some(Ok(_)), _) => {
-                        debug!("sync decoding {} ({:?})", url, key);
-                        decode_bytes_sync(key, &pl.bytes.as_slice())
-                    }
-                    (&None, &Some(ref meta)) => {
-                        debug!("metadata available for {} ({:?})", url, key);
-                        return Ok(ImageOrMetadataAvailable::MetadataAvailable(meta.clone()))
-                    }
-                    (&Some(Err(_)), _) | (&None, &None) => {
-                        debug!("{} ({:?}) is still pending", url, key);
-                        return Err(ImageState::Pending(key));
-                    }
-                },
-                CacheResult::Miss(Some((key, _pl))) => {
-                    debug!("should be requesting {} ({:?})", url, key);
-                    return Err(ImageState::NotRequested(key));
-                }
-                CacheResult::Miss(None) => {
-                    debug!("couldn't find an entry for {}", url);
-                    return Err(ImageState::LoadError);
-                }
-            }
-        };
-
-        // In the case where a decode is ongoing (or waiting in a queue) but we have the
-        // full response available, we decode the bytes synchronously and ignore the
-        // async decode when it finishes later.
-        // TODO: make this behaviour configurable according to the caller's needs.
-        self.handle_decoder(decoded);
-        match self.get_completed_image_if_available(&url, placeholder) {
-            Some(result) => result,
-            None => Err(ImageState::LoadError),
-        }
-    }
-}
-
-/// Create a new image cache.
-pub fn new_image_cache_thread(webrender_api: webrender_traits::RenderApi) -> ImageCacheThread {
-    let (ipc_command_sender, ipc_command_receiver) = ipc::channel().unwrap();
-
-    thread::Builder::new().name("ImageCacheThread".to_owned()).spawn(move || {
-        ImageCache::run(webrender_api, ipc_command_receiver)
-    }).expect("Thread spawning failed");
-
-    ImageCacheThread::new(ipc_command_sender)
-}
-
-fn decode_bytes_sync(key: LoadKey, bytes: &[u8]) -> DecoderMsg {
-    let image = load_from_memory(bytes);
-    DecoderMsg {
-        key: key,
-        image: image
-    }
-}