wasmtime-guest-pprof

A drop-in helper around wasmtime's GuestProfiler that handles:

• the take() / restore borrow-checker dance the sampling callback needs,
• the background thread that ticks engine.increment_epoch() to drive sampling,
• the Firefox Profiler JSON → pprof conversion (via firefox-to-pprof).

You still own:

• the wasmtime::Engine/Module/Linker (so you can declare host imports)
• your Store<T> data, which must implement [ProfilerHost] + [TakeProfileSession]

Sketch

use std::time::Duration;
use wasmtime::{Config, Engine, Module, Store};
use wasmtime_guest_pprof::{ProfileSession, ProfilerHost, ProfilerHostExt, TakeProfileSession};

struct App {
    profiler: ProfileSession,
    // ...your host state
}
impl ProfilerHost for App {
    fn profiler(&mut self) -> &mut ProfileSession { &mut self.profiler }
}
impl TakeProfileSession for App {
    fn take_session(store: Store<Self>) -> ProfileSession {
        store.into_data().profiler
    }
}

# fn main() -> anyhow::Result<()> {
let mut config = Config::new();
config.epoch_interruption(true);
config.generate_address_map(true);
let engine = Engine::new(&config)?;
let module = Module::from_file(&engine, "guest.wasm")?;

let session = ProfileSession::new(
    &engine,
    "my-guest",
    Duration::from_millis(1),
    vec![("guest.wasm".into(), module.clone())],
)?;
let mut store = Store::new(&engine, App { profiler: session });
App::install(&mut store);
let _ticker = App::start_ticker(&engine, Duration::from_millis(1));

// ...invoke guest exports against `store`...

drop(_ticker);
let bytes = App::finish_pprof(store)?;
std::fs::write("guest.pb.gz", bytes)?;
# Ok(())
# }

License

Apache-2.0