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22c4035692
Source-Repo: https://github.com/servo/servo Source-Revision: c5e1b0d32e17fad29799023c85e2e73ac89c3af7
169 lines
5.8 KiB
Rust
169 lines
5.8 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*!
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An adapter for ImageCacheTask that does local caching to avoid
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extra message traffic, it also avoids waiting on the same image
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multiple times and thus triggering reflows multiple times.
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*/
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use image_cache_task::{Decode, GetImage, ImageCacheTask, ImageFailed, ImageNotReady, ImageReady};
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use image_cache_task::{ImageResponseMsg, Prefetch, WaitForImage};
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use std::comm::{Receiver, channel};
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use std::collections::HashMap;
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use std::collections::hash_map::{Occupied, Vacant};
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use servo_util::task::spawn_named;
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use url::Url;
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pub trait ImageResponder<NodeAddress: Send> {
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fn respond(&self) -> proc(ImageResponseMsg, NodeAddress):Send;
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}
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pub struct LocalImageCache<NodeAddress> {
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image_cache_task: ImageCacheTask,
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round_number: uint,
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on_image_available: Option<Box<ImageResponder<NodeAddress>+Send>>,
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state_map: HashMap<Url, ImageState>
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}
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impl<NodeAddress: Send> LocalImageCache<NodeAddress> {
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pub fn new(image_cache_task: ImageCacheTask) -> LocalImageCache<NodeAddress> {
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LocalImageCache {
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image_cache_task: image_cache_task,
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round_number: 1,
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on_image_available: None,
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state_map: HashMap::new()
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}
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}
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}
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#[deriving(Clone)]
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struct ImageState {
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prefetched: bool,
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decoded: bool,
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last_request_round: uint,
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last_response: ImageResponseMsg
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}
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impl<NodeAddress: Send> LocalImageCache<NodeAddress> {
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/// The local cache will only do a single remote request for a given
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/// URL in each 'round'. Layout should call this each time it begins
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pub fn next_round(&mut self, on_image_available: Box<ImageResponder<NodeAddress> + Send>) {
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self.round_number += 1;
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self.on_image_available = Some(on_image_available);
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}
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pub fn prefetch(&mut self, url: &Url) {
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{
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let state = self.get_state(url);
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if state.prefetched {
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return
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}
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state.prefetched = true;
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}
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self.image_cache_task.send(Prefetch((*url).clone()));
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}
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pub fn decode(&mut self, url: &Url) {
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{
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let state = self.get_state(url);
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if state.decoded {
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return
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}
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state.decoded = true;
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}
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self.image_cache_task.send(Decode((*url).clone()));
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}
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// FIXME: Should return a Future
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pub fn get_image(&mut self, node_address: NodeAddress, url: &Url) -> Receiver<ImageResponseMsg> {
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{
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let round_number = self.round_number;
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let state = self.get_state(url);
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// Save the previous round number for comparison
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let last_round = state.last_request_round;
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// Set the current round number for this image
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state.last_request_round = round_number;
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match state.last_response {
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ImageReady(ref image) => {
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let (chan, port) = channel();
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chan.send(ImageReady(image.clone()));
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return port;
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}
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ImageNotReady => {
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if last_round == round_number {
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let (chan, port) = channel();
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chan.send(ImageNotReady);
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return port;
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} else {
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// We haven't requested the image from the
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// remote cache this round
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}
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}
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ImageFailed => {
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let (chan, port) = channel();
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chan.send(ImageFailed);
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return port;
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}
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}
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}
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let (response_chan, response_port) = channel();
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self.image_cache_task.send(GetImage((*url).clone(), response_chan));
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let response = response_port.recv();
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match response {
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ImageNotReady => {
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// Need to reflow when the image is available
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// FIXME: Instead we should be just passing a Future
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// to the caller, then to the display list. Finally,
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// the compositor should be resonsible for waiting
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// on the image to load and triggering layout
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let image_cache_task = self.image_cache_task.clone();
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assert!(self.on_image_available.is_some());
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let on_image_available: proc(ImageResponseMsg, NodeAddress):Send =
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self.on_image_available.as_ref().unwrap().respond();
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let url = (*url).clone();
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spawn_named("LocalImageCache", proc() {
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let (response_chan, response_port) = channel();
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image_cache_task.send(WaitForImage(url, response_chan));
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on_image_available(response_port.recv(), node_address);
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});
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}
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_ => ()
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}
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// Put a copy of the response in the cache
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let response_copy = match response {
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ImageReady(ref image) => ImageReady(image.clone()),
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ImageNotReady => ImageNotReady,
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ImageFailed => ImageFailed
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};
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self.get_state(url).last_response = response_copy;
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let (chan, port) = channel();
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chan.send(response);
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return port;
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}
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fn get_state<'a>(&'a mut self, url: &Url) -> &'a mut ImageState {
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match self.state_map.entry((*url).clone()) {
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Occupied(entry) => entry.into_mut(),
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Vacant(entry) =>
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entry.set(ImageState {
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prefetched: false,
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decoded: false,
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last_request_round: 0,
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last_response: ImageNotReady,
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})
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}
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}
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}
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