Operasi Asinkron dengan WASM
Implementasikan pola asinkron untuk menangani tugas yang berjalan lama dalam WASM tanpa memblokir thread utama, menggunakan promise dan async/await.
Operasi Asinkron dengan WASM adalah pelajaran WebAssembly (WASM) for High Performance Apps gratis di CoddyKit. Ini adalah pelajaran 1 dari 4. Kamu bisa membaca pelajaran lengkapnya di bawah secara gratis — lalu praktikkan langsung di browser dengan editor kode bawaan dan tutor AI 24/7. Ini adalah bagian dari jalur belajar WebAssembly (WASM) for High Performance Apps, dan progresmu tersinkronisasi di web dan aplikasi CoddyKit. Kursus WebAssembly (WASM) for High Performance Apps mencakup 4 pelajaran total.
Bagian dari pelajaran ini belum diterjemahkan dan ditampilkan dalam bahasa Inggris.
Why Asynchronous WASM?
When a WebAssembly module performs a complex calculation or a long task, it can freeze your web page. This is because JavaScript is single-threaded, and most direct WASM calls are synchronous.
Asynchronous WASM patterns allow these tasks to run without completely blocking the main browser thread, keeping your UI responsive.
WASM's Synchronous Nature
When JavaScript calls an exported WASM function, that function executes entirely before JavaScript regains control. If the WASM function takes a long time, the browser's main thread will be blocked.
This means no UI updates, no user input processing, making the page appear frozen. True parallel execution for WASM often involves Web Workers, which is covered in another lesson.
Strategy: Breaking into Chunks
To prevent blocking the main thread, we can break a long-running WASM task into smaller, manageable chunks. Instead of one huge, blocking WASM call, we make many small ones.
Between each small WASM call, JavaScript can yield control back to the browser's event loop. This allows the UI to update and remain responsive.
WASM Function for a Chunk
Here's a Rust function that represents one "chunk" of work. It takes a starting value and performs a small number of calculations. In a real application, this could process a part of an image or a segment of data.
pub extern "C" fn process_chunk(start_val: u32, iterations: u32) -> u32 {
let mut sum = start_val;
for i in 0..iterations {
sum = sum.wrapping_add(i); // Simulate work, prevent overflow
}
sum
}Promises in JavaScript
To handle asynchronous operations, JavaScript uses Promises. A Promise represents the eventual completion (or failure) of an asynchronous operation and its resulting value.
- Pending: Initial state, neither fulfilled nor rejected.
- Fulfilled: Operation completed successfully.
- Rejected: Operation failed.
We use .then() for success and .catch() for errors.
Simplifying with async/await
async/await is syntactic sugar built on Promises, making asynchronous code look and behave more like synchronous code, improving readability. It's built on Promises.
- An
asyncfunction always returns a Promise. - The
awaitkeyword can only be used inside anasyncfunction. It pauses the execution until the Promise settles, allowing other tasks to run.
This is crucial for orchestrating our WASM chunks.
Making WASM Calls Yield
We can create a JavaScript utility function that wraps a synchronous WASM call in a Promise. By using setTimeout(..., 0), we tell the browser to execute the WASM call after the current event loop cycle finishes.
This effectively "yields" control back to the browser, allowing it to update the UI before the next WASM chunk runs.
function callWasmAsync(wasmExports, funcName, ...args) {
return new Promise(resolve => {
setTimeout(() => {
const result = wasmExports[funcName](...args);
resolve(result);
}, 0); // Yield control to the event loop
});
}Full Async WASM Example
Here's a complete, runnable example demonstrating how to manage a long-running WASM task asynchronously using chunking and JavaScript's async/await.
Notice how `setTimeout(0)` around the WASM call allows the browser to breathe between chunks.
// main.js
// Assume wasm_module.wasm (containing process_chunk) is loaded.
// For this runnable example, we'll simulate the WASM function.
// This simulates our WASM module's process_chunk function
function simulateWasmProcessChunk(start_val, iterations) {
let sum = start_val;
for (let i = 0; i < iterations; i++) {
sum = (sum + i) % 10000; // Simplified calculation
}
return sum;
}
// Utility to call a synchronous task asynchronously
function callSyncTaskAsync(taskFunc, ...args) {
return new Promise(resolve => {
setTimeout(() => {
const result = taskFunc(...args);
resolve(result);
}, 0); // Yield control to the event loop
});
}
async function performLongTask() {
console.log("Starting async task...");
let currentSum = 0;
const totalChunks = 5;
const iterationsPerChunk = 10_000_000; // Simulate heavy work
for (let i = 0; i < totalChunks; i++) {
// Call the simulated WASM chunk asynchronously
currentSum = await callSyncTaskAsync(
simulateWasmProcessChunk,
currentSum,
iterationsPerChunk
);
console.log(`Chunk ${i + 1} done. Current sum: ${currentSum}`);
}
console.log("Async task finished. Final sum:", currentSum);
return currentSum;
}
performLongTask();Handling Errors Asynchronously
Just like any asynchronous operation, you should handle potential errors. If a WASM chunk call fails (e.g., due to invalid input or memory issues), the Promise will reject.
You can use try...catch with async/await or .catch() with Promises to gracefully handle these situations in your JavaScript code.
Async WASM Check
Consider a WebAssembly function heavy_calc() that takes 5 seconds to run. If you call it directly from JavaScript's main thread, what is the primary consequence?
Recap: Async WASM Patterns
We've learned how to handle long-running WASM tasks asynchronously on the main thread without using Web Workers. Key takeaways:
- WASM functions are synchronous when called from JavaScript.
- Break long tasks into smaller "chunks."
- Use JavaScript Promises and
async/awaitto orchestrate these chunks. - Yield control to the browser's event loop (e.g., with
setTimeout(0)) between chunk calls to keep the UI responsive.
This pattern is crucial for maintaining a smooth user experience in complex web applications.
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Tulis dan jalankan kode asli di browser kamu, dapatkan bantuan instan dari tutor AI 24/7, dan lanjutkan di mana kamu tinggalkan di web atau aplikasi.
- Kursus
- 12
- Pelajaran
- 48
Pertanyaan yang Sering Diajukan
Apakah pelajaran “Operasi Asinkron dengan WASM” gratis?
Ya — teks lengkap “Operasi Asinkron dengan WASM” gratis dibaca di sini di web. Untuk praktiknya secara interaktif (editor kode bawaan dan tutor AI 24/7) dan buka sisa kursus WebAssembly (WASM) for High Performance Apps, upgrade ke CoddyKit PRO. Kursus WebAssembly (WASM) for High Performance Apps mencakup 4 pelajaran total.
Apa yang akan aku pelajari di “Operasi Asinkron dengan WASM”?
Implementasikan pola asinkron untuk menangani tugas yang berjalan lama dalam WASM tanpa memblokir thread utama, menggunakan promise dan async/await. Kamu berlatih WebAssembly (WASM) for High Performance Apps dengan kode praktik yang langsung kamu jalankan di browser, dan tutor AI 24/7 menjawab pertanyaanmu saat kamu mengerjakan pelajaran ini.
Apakah aku perlu pengalaman untuk memulai WebAssembly (WASM) for High Performance Apps?
Tidak diperlukan pengalaman sebelumnya. WebAssembly (WASM) for High Performance Apps di CoddyKit dirancang untuk pemula hingga pelajar tingkat lanjut, jadi kamu bisa memulai di sini atau dari awal dan belajar sesuai kecepatan kamu sendiri. Ini adalah pelajaran 1 dari 4.
Berapa lama pelajaran “Operasi Asinkron dengan WASM” memakan waktu?
Sebagian besar pelajaran CoddyKit memakan waktu sekitar 5–10 menit. Setiap pelajaran ringkas dan interaktif, jadi kamu membuat kemajuan stabil dan melanjutkan dari tempat kamu tinggalkan di web dan aplikasi.
Bisakah aku menulis dan menjalankan kode dalam pelajaran WebAssembly (WASM) for High Performance Apps ini?
Ya. Setiap pelajaran WebAssembly (WASM) for High Performance Apps menyertakan editor kode bawaan, jadi kamu menulis dan menjalankan kode nyata langsung di browser dan mendapatkan umpan balik AI instan — tidak diperlukan penyiapan lokal.
Semua pelajaran dalam kursus ini
- Operasi Asinkron dengan WASM
- Callback JavaScript Khusus
- Penanganan Kesalahan & Eksepsi
- Berbagi Memori dan Larik Bertipe di Seluruh Batas JS/WASM