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//! Measure some common WASI call scenarios.
use criterion::{criterion_group, criterion_main, Criterion};
use std::{fs::File, path::Path, time::Instant};
use wasmtime::{Engine, Linker, Module, Store, TypedFunc};
use wasmtime_wasi::{sync::WasiCtxBuilder, WasiCtx};
criterion_group!(benches, bench_wasi);
criterion_main!(benches);
fn bench_wasi(c: &mut Criterion) {
let _ = env_logger::try_init();
// Build a zero-filled test file if it does not yet exist.
let test_file = Path::new("benches/wasi/test.bin");
if !test_file.is_file() {
let file = File::create(test_file).unwrap();
file.set_len(4096).unwrap();
}
// Benchmark each `*.wat` file in the `wasi` directory.
for file in std::fs::read_dir("benches/wasi").unwrap() {
let path = file.unwrap().path();
if path.extension().map(|e| e == "wat").unwrap_or(false) {
let wat = std::fs::read(&path).unwrap();
let (mut store, run_fn) = instantiate(&wat);
let bench_name = format!("wasi/{}", path.file_name().unwrap().to_string_lossy());
// To avoid overhead, the module itself must iterate the expected
// number of times in a specially-crafted `run` function (see
// `instantiate` for details).
c.bench_function(&bench_name, move |b| {
b.iter_custom(|iters| {
let start = Instant::now();
let result = run_fn.call(&mut store, iters).unwrap();
assert_eq!(iters, result);
start.elapsed()
})
});
}
}
}
/// Compile and instantiate the Wasm module, returning the exported `run`
/// function. This function expects `run` to:
/// - have a single `u64` parameter indicating the number of loop iterations to
/// execute
/// - execute the body of the function for that number of loop iterations
/// - return a single `u64` indicating how many loop iterations were executed
/// (to double-check)
fn instantiate(wat: &[u8]) -> (Store<WasiCtx>, TypedFunc<u64, u64>) {
let engine = Engine::default();
let wasi = wasi_context();
let mut store = Store::new(&engine, wasi);
let module = Module::new(&engine, wat).unwrap();
let mut linker = Linker::new(&engine);
wasmtime_wasi::add_to_linker(&mut linker, |cx| cx).unwrap();
let instance = linker.instantiate(&mut store, &module).unwrap();
let run = instance.get_typed_func(&mut store, "run").unwrap();
(store, run)
}
/// Build a WASI context with some actual data to retrieve.
fn wasi_context() -> WasiCtx {
WasiCtxBuilder::new()
.envs(&[
("a".to_string(), "b".to_string()),
("b".to_string(), "c".to_string()),
("c".to_string(), "d".to_string()),
])
.unwrap()
.args(&[
"exe".to_string(),
"--flag1".to_string(),
"--flag2".to_string(),
"--flag3".to_string(),
"--flag4".to_string(),
])
.unwrap()
.preopened_dir(
wasmtime_wasi::Dir::open_ambient_dir(
"benches/wasi",
wasmtime_wasi::ambient_authority(),
)
.unwrap(),
"/",
)
.unwrap()
.build()
}