src,v8: add wasm streaming handler api #42843
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Maybe this would be a good candidate for an embedder API?
If we really want to expose this as a JavaScript API, the documentation should be very clear about the security implications. Loading compiled code from an untrusted origin defeats all security properties of WebAssembly.
| @@ -245,6 +245,16 @@ function setupFetch() { | |||
| throw new ERR_WEBASSEMBLY_RESPONSE('body has already been used'); | |||
| } | |||
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| const handler = require('internal/v8').getWasmStreamingHandler(); | |||
| const cached = await handler?.get(response.url); | |||
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As I understand this, this will only work when loading WebAssembly from a remote origin, and only if the URL is stable, and only if the WebAssembly module does not change.
| if (streamState.setCompiledModuleBytes(cached)) { | ||
| return; | ||
| } else { | ||
| await handler.delete(response.url); |
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In this case, V8 has decided not to use the compiled code. That can happen, for example, when running node with certain V8 flags. However, actively deleting something from the cache means that two Node.js processes running with different command-line flags but using the same WebAssembly cache will keep filling and erasing the cache.
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@tniessen that's a really good point. Do you see a way to isolate this deletion?
| env->wasm_streaming_compilation_callback() | ||
| ->Call( | ||
| env->context(), Undefined(env->isolate()), arraysize(args), args) | ||
| .ToLocalChecked(); |
this allows user code to take full advantage of v8's wasm streaming api by caching previously compiled modules.
Fixes: #36671