You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
33 lines
1.2 KiB
33 lines
1.2 KiB
//! Example of limiting a WebAssembly function's runtime using "fuel consumption".
|
|
|
|
// You can execute this example with `cargo run --example fuel`
|
|
|
|
use anyhow::Result;
|
|
use wasmtime::*;
|
|
|
|
fn main() -> Result<()> {
|
|
let mut config = Config::new();
|
|
config.consume_fuel(true);
|
|
let engine = Engine::new(&config)?;
|
|
let mut store = Store::new(&engine, ());
|
|
store.add_fuel(10_000)?;
|
|
let module = Module::from_file(store.engine(), "examples/fuel.wat")?;
|
|
let instance = Instance::new(&mut store, &module, &[])?;
|
|
|
|
// Invoke `fibonacci` export with higher and higher numbers until we exhaust our fuel.
|
|
let fibonacci = instance.get_typed_func::<i32, i32, _>(&mut store, "fibonacci")?;
|
|
for n in 1.. {
|
|
let fuel_before = store.fuel_consumed().unwrap();
|
|
let output = match fibonacci.call(&mut store, n) {
|
|
Ok(v) => v,
|
|
Err(_) => {
|
|
println!("Exhausted fuel computing fib({})", n);
|
|
break;
|
|
}
|
|
};
|
|
let fuel_consumed = store.fuel_consumed().unwrap() - fuel_before;
|
|
println!("fib({}) = {} [consumed {} fuel]", n, output, fuel_consumed);
|
|
store.add_fuel(fuel_consumed)?;
|
|
}
|
|
Ok(())
|
|
}
|
|
|