2018-12-21 17:03:26 +01:00
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// 1. +++ fetchAndInstantiate() +++ //
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// This library function fetches the wasm module at 'url', instantiates it with
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// the given 'importObject', and returns the instantiated object instance
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2018-12-27 18:27:26 +01:00
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export async function instantiateStreaming(url, importObject) {
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let result = await WebAssembly.instantiateStreaming(fetch(url), importObject);
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return result.instance;
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2018-12-21 17:03:26 +01:00
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}
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export function fetchAndInstantiate(url, importObject) {
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return fetch(url)
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.then(response => response.arrayBuffer())
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.then(bytes => WebAssembly.instantiate(bytes, importObject))
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.then(results => results.instance);
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}
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// 2. +++ instantiateCachedURL() +++ //
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// This library function fetches the wasm Module at 'url', instantiates it with
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// the given 'importObject', and returns a Promise resolving to the finished
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// wasm Instance. Additionally, the function attempts to cache the compiled wasm
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// Module in IndexedDB using 'url' as the key. The entire site's wasm cache (not
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// just the given URL) is versioned by dbVersion and any change in dbVersion on
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// any call to instantiateCachedURL() will conservatively clear out the entire
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// cache to avoid stale modules.
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export function instantiateCachedURL(dbVersion, url, importObject) {
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const dbName = 'wasm-cache';
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const storeName = 'wasm-cache';
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// This helper function Promise-ifies the operation of opening an IndexedDB
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// database and clearing out the cache when the version changes.
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function openDatabase() {
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return new Promise((resolve, reject) => {
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var request = indexedDB.open(dbName, dbVersion);
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request.onerror = reject.bind(null, 'Error opening wasm cache database');
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request.onsuccess = () => {
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resolve(request.result);
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};
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request.onupgradeneeded = event => {
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var db = request.result;
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if (db.objectStoreNames.contains(storeName)) {
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console.log(`Clearing out version ${event.oldVersion} wasm cache`);
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db.deleteObjectStore(storeName);
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}
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console.log(`Creating version ${event.newVersion} wasm cache`);
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db.createObjectStore(storeName);
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};
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});
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}
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// This helper function Promise-ifies the operation of looking up 'url' in the
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// given IDBDatabase.
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function lookupInDatabase(db) {
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return new Promise((resolve, reject) => {
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var store = db.transaction([storeName]).objectStore(storeName);
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var request = store.get(url);
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request.onerror = reject.bind(null, `Error getting wasm module ${url}`);
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request.onsuccess = event => {
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if (request.result) resolve(request.result);
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else reject(`Module ${url} was not found in wasm cache`);
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};
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});
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}
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// This helper function fires off an async operation to store the given wasm
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// Module in the given IDBDatabase.
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function storeInDatabase(db, module) {
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var store = db.transaction([storeName], 'readwrite').objectStore(storeName);
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var request = store.put(module, url);
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request.onerror = err => {
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console.log(`Failed to store in wasm cache: ${err}`);
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};
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request.onsuccess = err => {
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console.log(`Successfully stored ${url} in wasm cache`);
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};
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}
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// This helper function fetches 'url', compiles it into a Module,
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// instantiates the Module with the given import object.
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function fetchAndInstantiate() {
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return fetch(url)
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.then(response => response.arrayBuffer())
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.then(buffer => WebAssembly.instantiate(buffer, importObject));
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}
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// With all the Promise helper functions defined, we can now express the core
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// logic of an IndexedDB cache lookup. We start by trying to open a database.
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return openDatabase().then(
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db => {
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// Now see if we already have a compiled Module with key 'url' in 'db':
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return lookupInDatabase(db).then(
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module => {
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// We do! Instantiate it with the given import object.
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console.log(`Found ${url} in wasm cache`);
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return WebAssembly.instantiate(module, importObject);
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},
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errMsg => {
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// Nope! Compile from scratch and then store the compiled Module in 'db'
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// with key 'url' for next time.
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console.log(errMsg);
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return fetchAndInstantiate().then(results => {
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try {
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storeInDatabase(db, results.module);
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} catch (e) {
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console.log('Failed to store module into db');
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}
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return results.instance;
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});
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}
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);
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},
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errMsg => {
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// If opening the database failed (due to permissions or quota), fall back
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// to simply fetching and compiling the module and don't try to store the
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// results.
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console.log(errMsg);
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return fetchAndInstantiate().then(results => results.instance);
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}
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);
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}
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2018-12-27 18:27:26 +01:00
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export async function instantiateAny(version, url, importObject) {
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console.log("instantiate");
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try {
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2018-12-27 20:24:44 +01:00
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return await instantiateStreaming(url, importObject);
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2018-12-27 18:27:26 +01:00
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} catch (e) {
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console.log("instantiateSteaming failed", e);
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}
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try {
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2018-12-27 20:24:44 +01:00
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return await instantiateCachedURL(version, url, importObject);
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2018-12-27 18:27:26 +01:00
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} catch (e) {
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console.log("instantiateCachedURL failed", e);
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}
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throw new Error("can't instantiate wasm");
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}
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