rusty_v8_minimum_snapshot.rs

use rusty_v8 as v8;
use std::mem::forget;

fn main() {
    let platform = v8::new_default_platform().unwrap();
    v8::V8::initialize_platform(platform);
    v8::V8::initialize();
    let snapshot;
    // --- create snapshot ---
    {
        let mut creator = v8::SnapshotCreator::new(None);
        let mut isolate = unsafe { creator.get_owned_isolate() };
        {
            let scope = &mut v8::HandleScope::new(&mut isolate);
            let context = v8::Context::new(scope);
            let src = r#"
                function add1(n) { return n + 1; }
                x = 1;
                y = 2;
                add1(x + y);
            "#;
            {
                let scope = &mut v8::ContextScope::new(scope, context);
                let code = v8::String::new(scope, src).unwrap();
                let script = v8::Script::compile(scope, code, None).unwrap();
                let result = script.run(scope).unwrap();
                assert_eq!(result.to_rust_string_lossy(scope), "4");
            }
            creator.set_default_context(context);
        }

        snapshot = creator.create_blob(v8::FunctionCodeHandling::Keep).unwrap();
        let snapshot_slice: &[u8] = &*snapshot;
        println!("Snapshot size: {} kb", snapshot_slice.len() / 1024);
        forget(isolate);
    }

    // --- restore snapshot ---
    {
        let mut isolate = v8::Isolate::new(v8::Isolate::create_params().snapshot_blob(snapshot));
        let scope = &mut v8::HandleScope::new(&mut isolate);
        let context = v8::Context::new(scope);
        {
            let scope = &mut v8::ContextScope::new(scope, context);
            let code = v8::String::new(scope, "add1(x + y)").unwrap();
            let script = v8::Script::compile(scope, code, None).unwrap();
            let result = script.run(scope).unwrap();
            assert_eq!(result.to_rust_string_lossy(scope), "4");
        }
    }
}