CODEWITHSUNDEEP
javascriptwebassembly
user2847643
user2847643

Reputation: 2935

Terminate WebAssembly from JavaScript

Is it possible to terminate running WebAssembly code and cleanup any remaining resources from JavaScript?

In general the scenario is this. JS initializes a WASM module and calls an exported function. At a later point in time WASM code calls an imported function f transferring control back to JS. f does some stuff and based on the result decides whether to keep WASM running or not.

Two cases:

If it would make it easier to analyze a more concrete example think how execve works. If the call fails it simply returns indicating failure. However if it succeeds it does not return - a broad oversimplification would be to say it terminates the caller and starts a new one in it's place (keeping some of the environment unchanged).

Upvotes: 1

Views: 813

Answers (1)

Andreas Rossberg
Andreas Rossberg

Reputation: 36098

The only way to possibly terminate a caller -- no matter whether the caller is Wasm or JavaScript -- is to throw an exception. That leaves it up to the caller to react adequately. In particular, if it needs to do cleanup then it should be written such that it catches possible exceptions, performs the cleanup, and rethrows (or, equivalently, use a try-finally construct when available).

Wasm does not currently support exception handling directly, but that can be emulated by thunking out to JavaScript. Future versions of Wasm will have proper exception handling support.

Upvotes: 2

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