sffc/bigbox.rs

## bigbox.rs
// Build this file with:
// rustc --target wasm32-unknown-unknown bigbox.rs

#![crate_type = "cdylib"]

type INNER = Vec<u8>;

#[no_mangle]
pub extern "C" fn make_big_box(len: usize) -> *mut core::ffi::c_void {
	let memory: Box<INNER> = Box::new(vec![0; len]);
	Box::into_raw(memory) as *mut core::ffi::c_void
}

#[no_mangle]
pub unsafe extern "C" fn free_big_box(ptr: *mut core::ffi::c_void) {
	Box::from_raw(ptr as *mut INNER);
}

## bigbox_frontend.html
<!DOCTYPE html>
<!--
View online at:
https://storage.googleapis.com/static-493776/crbug13958/bigbox_frontend.html
-->

<script type="text/javascript">
let wasmInstance;
async function main() {
	const wasmResponse = await fetch("./bigbox.wasm");
	const wasmBuffer = await wasmResponse.arrayBuffer();
	const wasmResult = await WebAssembly.instantiate(wasmBuffer);
	wasmInstance = wasmResult.instance;
}
main();
function updateView() {
	document.getElementById("wasmsize").innerText = wasmInstance.exports.memory.buffer.byteLength;
}
const registry = new FinalizationRegistry(({ ptr, len }) => {
	if (ptr) wasmInstance.exports.free_big_box(ptr);
	let s = ptr ? `Wasm object at ${ptr}` : `ArrayBuffer with length ${len}`;
	updateView();
	const time = new Date().toLocaleString(undefined, { hour: "numeric", minute: "numeric", second: "numeric", fractionalSecondDigits: 3 });
	document.getElementById("collected").innerHTML = `<li>${time} - ${s}</li>` + document.getElementById("collected").innerHTML;
});
function createBigBox(len) {
	if (!wasmInstance) {
		alert("Please wait for the wasm instance to finish loading");
		return;
	}
	const ptr = wasmInstance.exports.make_big_box(len);
	const obj = { _inner: ptr };
	registry.register(obj, { ptr });
	updateView();
	return obj;
}
function createBigArrayBuffer(len) {
	const buffer = new ArrayBuffer(len);
	registry.register(buffer, { len });
}
window.ablen = 1000000;
</script>

<p>
	Total WASM linear memory length: <span id="wasmsize"></span>
</p>

<p>
	<button onclick="createBigBox(1000000)">Make New 1MB Wasm Object</button>
</p>

<p>
	<button onclick="window.ablen++; createBigArrayBuffer(window.ablen)">Make New 1MB ArrayBuffer</button>
</p>

<p>
	Objects collected:
	<ul id="collected"></ul>
</p>
	// Build this file with:
	// rustc --target wasm32-unknown-unknown bigbox.rs

	#![crate_type = "cdylib"]

	type INNER = Vec<u8>;

	#[no_mangle]
	pub extern "C" fn make_big_box(len: usize) -> *mut core::ffi::c_void {
	let memory: Box<INNER> = Box::new(vec![0; len]);
	Box::into_raw(memory) as *mut core::ffi::c_void
	}

	#[no_mangle]
	pub unsafe extern "C" fn free_big_box(ptr: *mut core::ffi::c_void) {
	Box::from_raw(ptr as *mut INNER);
	}
	<!DOCTYPE html>
	<!--
	View online at:
	https://storage.googleapis.com/static-493776/crbug13958/bigbox_frontend.html
	-->

	<script type="text/javascript">
	let wasmInstance;
	async function main() {
	const wasmResponse = await fetch("./bigbox.wasm");
	const wasmBuffer = await wasmResponse.arrayBuffer();
	const wasmResult = await WebAssembly.instantiate(wasmBuffer);
	wasmInstance = wasmResult.instance;
	}
	main();
	function updateView() {
	document.getElementById("wasmsize").innerText = wasmInstance.exports.memory.buffer.byteLength;
	}
	const registry = new FinalizationRegistry(({ ptr, len }) => {
	if (ptr) wasmInstance.exports.free_big_box(ptr);
	let s = ptr ? `Wasm object at ${ptr}` : `ArrayBuffer with length ${len}`;
	updateView();
	const time = new Date().toLocaleString(undefined, { hour: "numeric", minute: "numeric", second: "numeric", fractionalSecondDigits: 3 });
	document.getElementById("collected").innerHTML = `<li>${time} - ${s}</li>` + document.getElementById("collected").innerHTML;
	});
	function createBigBox(len) {
	if (!wasmInstance) {
	alert("Please wait for the wasm instance to finish loading");
	return;
	}
	const ptr = wasmInstance.exports.make_big_box(len);
	const obj = { _inner: ptr };
	registry.register(obj, { ptr });
	updateView();
	return obj;
	}
	function createBigArrayBuffer(len) {
	const buffer = new ArrayBuffer(len);
	registry.register(buffer, { len });
	}
	window.ablen = 1000000;
	</script>

	<p>
	Total WASM linear memory length: <span id="wasmsize"></span>
	</p>

	<p>
	<button onclick="createBigBox(1000000)">Make New 1MB Wasm Object</button>
	</p>

	<p>
	<button onclick="window.ablen++; createBigArrayBuffer(window.ablen)">Make New 1MB ArrayBuffer</button>
	</p>

	<p>
	Objects collected:
	<ul id="collected"></ul>
	</p>