Persistent data | Deno | Page 1

gleaming pendant Dec 4, 2022, 7:33 PM

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According to the V8 documentation, if I want an object to exist across multiple independent operations I'd have to use a Persistent handle although I see no references to it outside of a few documentation mentions here: https://github.com/denoland/rusty_v8/search?q=persistent

Am I supposed to do it in a different way with Deno?

GitHub

Search · persistent · denoland/rusty_v8

Rust bindings for the V8 JavaScript engine. Contribute to denoland/rusty_v8 development by creating an account on GitHub.

hard pelican Dec 4, 2022, 7:39 PM

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Some of the differences between handle types in V8 are the way they are because of C++ semantics, not all of which map cleanly to Rust

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For a handle to exist across multiple independent operations, in rusty_v8 you'd use a v8::Global

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https://docs.rs/v8/latest/v8/struct.Global.html

Global in v8 - Rust

An object reference that is independent of any handle scope. Where a Local handle only lives as long as the HandleScope in which it was allocated, a global handle remains valid until it is explicitly disposed using reset().

paper condor Dec 4, 2022, 7:41 PM

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And specifically the reason is that Persistent has copy semantics while Global has move semantics. How that relates to rusty_v8 needing to use Global instead of Persistent I'm not quite sure, though 🙂

hard pelican Dec 4, 2022, 7:44 PM

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Rust's move semantics are just changing ownership

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which you can do with Global

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and you can also clone a Global

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so I guess that's fine?

#Persistent data