79 lines
2.0 KiB
JavaScript
79 lines
2.0 KiB
JavaScript
import {LRUCache} from 'lru-cache';
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const cache = new LRUCache({
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max: 128,
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});
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export async function computeMissing(current, manifest) {
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const missing = [];
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for (const path in manifest) {
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if (!current || !current[path] || current[path].hash !== manifest[path]) {
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missing.push(path);
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}
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}
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return missing;
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}
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const octets = [];
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for (let i = 0; i < 256; ++i) {
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octets.push(i.toString(16).padStart(2, '0'));
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}
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export async function parseResources(resources, buffer) {
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const view = new DataView(buffer);
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let caret = 0;
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const count = view.getUint32(caret);
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caret += 4;
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const manifest = {};
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for (let i = 0; i < count; ++i) {
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let hash = '';
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for (let j = 0; j < 20; ++j) {
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hash += octets[view.getUint8(caret)]
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caret += 1;
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}
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const byteLength = view.getUint32(caret);
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caret += 4;
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const asset = new ArrayBuffer(byteLength);
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const assetView = new DataView(asset);
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for (let j = 0; j < asset.byteLength; ++j) {
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assetView.setUint8(j, view.getUint8(caret));
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caret += 1;
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}
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manifest[resources[i]] = {asset, hash};
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}
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return manifest;
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}
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export async function fetchResources(paths, {signal} = {}) {
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const response = await fetch('/resources/stream', {
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body: JSON.stringify(paths),
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method: 'post',
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signal,
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});
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if (signal.aborted) {
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return undefined;
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}
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return parseResources(paths, await response.arrayBuffer());
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}
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export async function get() {
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const {get} = await import('idb-keyval');
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const resources = await get('$$silphius_resources');
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return resources || {};
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}
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export async function set(resources) {
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const {set} = await import('idb-keyval');
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cache.clear();
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await set('$$silphius_resources', resources);
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}
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export async function readAsset(path) {
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if (!cache.has(path)) {
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const {pathname} = new URL(path, 'http://example.org');
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const resourcePath = pathname.slice('/resources/'.length);
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cache.set(path, get().then((resources) => resources[resourcePath]?.asset));
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}
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return cache.get(path);
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}
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