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2697a18d2f6907ab957ca6578389030b55cc55a9
wasmtime/tests/all/host_funcs.rs
Alex Crichton 2697a18d2f Redo the statically typed Func API (#2719) 
* Redo the statically typed `Func` API

This commit reimplements the `Func` API with respect to statically typed
dispatch. Previously `Func` had a `getN` and `getN_async` family of
methods which were implemented for 0 to 16 parameters. The return value
of these functions was an `impl Fn(..)` closure with the appropriate
parameters and return values.

There are a number of downsides with this approach that have become
apparent over time:

* The addition of `*_async` doubled the API surface area (which is quite
  large here due to one-method-per-number-of-parameters).
* The [documentation of `Func`][old-docs] are quite verbose and feel
  "polluted" with all these getters, making it harder to understand the
  other methods that can be used to interact with a `Func`.
* These methods unconditionally pay the cost of returning an owned `impl
  Fn` with a `'static` lifetime. While cheap, this is still paying the
  cost for cloning the `Store` effectively and moving data into the
  closed-over environment.
* Storage of the return value into a struct, for example, always
  requires `Box`-ing the returned closure since it otherwise cannot be
  named.
* Recently I had the desire to implement an "unchecked" path for
  invoking wasm where you unsafely assert the type signature of a wasm
  function. Doing this with today's scheme would require doubling
  (again) the API surface area for both async and synchronous calls,
  further polluting the documentation.

The main benefit of the previous scheme is that by returning a `impl Fn`
it was quite easy and ergonomic to actually invoke the function. In
practice, though, examples would often have something akin to
`.get0::<()>()?()?` which is a lot of things to interpret all at once.
Note that `get0` means "0 parameters" yet a type parameter is passed.
There's also a double function invocation which looks like a lot of
characters all lined up in a row.

Overall, I think that the previous design is starting to show too many
cracks and deserves a rewrite. This commit is that rewrite.

The new design in this commit is to delete the `getN{,_async}` family of
functions and instead have a new API:

    impl Func {
        fn typed<P, R>(&self) -> Result<&Typed<P, R>>;
    }

    impl Typed<P, R> {
        fn call(&self, params: P) -> Result<R, Trap>;
        async fn call_async(&self, params: P) -> Result<R, Trap>;
    }

This should entirely replace the current scheme, albeit by slightly
losing ergonomics use cases. The idea behind the API is that the
existence of `Typed<P, R>` is a "proof" that the underlying function
takes `P` and returns `R`. The `Func::typed` method peforms a runtime
type-check to ensure that types all match up, and if successful you get
a `Typed` value. Otherwise an error is returned.

Once you have a `Typed` then, like `Func`, you can either `call` or
`call_async`. The difference with a `Typed`, however, is that the
params/results are statically known and hence these calls can be much
more efficient.

This is a much smaller API surface area from before and should greatly
simplify the `Func` documentation. There's still a problem where
`Func::wrapN_async` produces a lot of functions to document, but that's
now the sole offender. It's a nice benefit that the
statically-typed-async verisons are now expressed with an `async`
function rather than a function-returning-a-future which makes it both
more efficient and easier to understand.

The type `P` and `R` are intended to either be bare types (e.g. `i32`)
or tuples of any length (including 0). At this time `R` is only allowed
to be `()` or a bare `i32`-style type because multi-value is not
supported with a native ABI (yet). The `P`, however, can be any size of
tuples of parameters. This is also where some ergonomics are lost
because instead of `f(1, 2)` you now have to write `f.call((1, 2))`
(note the double-parens). Similarly `f()` becomes `f.call(())`.

Overall I feel that this is a better tradeoff than before. While not
universally better due to the loss in ergonomics I feel that this design
is much more flexible in terms of what you can do with the return value
and also understanding the API surface area (just less to take in).

[old-docs]: https://docs.rs/wasmtime/0.24.0/wasmtime/struct.Func.html#method.get0

* Rename Typed to TypedFunc

* Implement multi-value returns through `Func::typed`

* Fix examples in docs

* Fix some more errors

* More test fixes

* Rebasing and adding `get_typed_func`

* Updating tests

* Fix typo

* More doc tweaks

* Tweak visibility on `Func::invoke`

* Fix tests again
2021-03-11 14:43:34 -06:00

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use anyhow::Result;
use std::sync::atomic::{AtomicUsize, Ordering::SeqCst};
use wasi_cap_std_sync::WasiCtxBuilder;
use wasmtime::*;
use wasmtime_wasi::Wasi;
#[test]
fn async_required() {
let mut config = Config::default();
config.define_host_func_async(
"",
"",
FuncType::new(None, None),
move |_caller, _params, _results| Box::new(async { Ok(()) }),
);
assert_eq!(
Engine::new(&config)
.map_err(|e| e.to_string())
.err()
.unwrap(),
"an async host function cannot be defined without async support enabled in the config"
);
}
#[test]
fn wrap_func() {
let mut config = Config::default();
config.wrap_host_func("", "", || {});
config.wrap_host_func("m", "f", |_: i32| {});
config.wrap_host_func("m", "f2", |_: i32, _: i64| {});
config.wrap_host_func("m2", "f", |_: f32, _: f64| {});
config.wrap_host_func("m2", "f2", || -> i32 { 0 });
config.wrap_host_func("", "", || -> i64 { 0 });
config.wrap_host_func("m", "f", || -> f32 { 0.0 });
config.wrap_host_func("m2", "f", || -> f64 { 0.0 });
config.wrap_host_func("m3", "", || -> Option<ExternRef> { None });
config.wrap_host_func("m3", "f", || -> Option<Func> { None });
config.wrap_host_func("", "f1", || -> Result<(), Trap> { loop {} });
config.wrap_host_func("", "f2", || -> Result<i32, Trap> { loop {} });
config.wrap_host_func("", "f3", || -> Result<i64, Trap> { loop {} });
config.wrap_host_func("", "f4", || -> Result<f32, Trap> { loop {} });
config.wrap_host_func("", "f5", || -> Result<f64, Trap> { loop {} });
config.wrap_host_func("", "f6", || -> Result<Option<ExternRef>, Trap> { loop {} });
config.wrap_host_func("", "f7", || -> Result<Option<Func>, Trap> { loop {} });
}
#[test]
fn drop_func() -> Result<()> {
static HITS: AtomicUsize = AtomicUsize::new(0);
struct A;
impl Drop for A {
fn drop(&mut self) {
HITS.fetch_add(1, SeqCst);
}
}
let mut config = Config::default();
let a = A;
config.wrap_host_func("", "", move || {
drop(&a);
});
assert_eq!(HITS.load(SeqCst), 0);
// Define the function again to ensure redefined functions are dropped
let a = A;
config.wrap_host_func("", "", move || {
drop(&a);
});
assert_eq!(HITS.load(SeqCst), 1);
drop(config);
assert_eq!(HITS.load(SeqCst), 2);
Ok(())
}
#[test]
fn drop_delayed() -> Result<()> {
static HITS: AtomicUsize = AtomicUsize::new(0);
struct A;
impl Drop for A {
fn drop(&mut self) {
HITS.fetch_add(1, SeqCst);
}
}
let mut config = Config::default();
let a = A;
config.wrap_host_func("", "", move || drop(&a));
assert_eq!(HITS.load(SeqCst), 0);
let engine = Engine::new(&config)?;
let module = Module::new(&engine, &wat::parse_str(r#"(import "" "" (func))"#)?)?;
let store = Store::new(&engine);
let instance = Instance::new(
&store,
&module,
&[store
.get_host_func("", "")
.expect("function should be defined")
.into()],
)?;
drop((instance, store));
assert_eq!(HITS.load(SeqCst), 0);
let store = Store::new(&engine);
let instance = Instance::new(
&store,
&module,
&[store
.get_host_func("", "")
.expect("function should be defined")
.into()],
)?;
drop((instance, store, engine, module));
assert_eq!(HITS.load(SeqCst), 0);
drop(config);
assert_eq!(HITS.load(SeqCst), 1);
Ok(())
}
#[test]
fn signatures_match() -> Result<()> {
let mut config = Config::default();
config.wrap_host_func("", "f1", || {});
config.wrap_host_func("", "f2", || -> i32 { loop {} });
config.wrap_host_func("", "f3", || -> i64 { loop {} });
config.wrap_host_func("", "f4", || -> f32 { loop {} });
config.wrap_host_func("", "f5", || -> f64 { loop {} });
config.wrap_host_func(
"",
"f6",
|_: f32, _: f64, _: i32, _: i64, _: i32, _: Option<ExternRef>, _: Option<Func>| -> f64 {
loop {}
},
);
let engine = Engine::new(&config)?;
let store = Store::new(&engine);
let f = store
.get_host_func("", "f1")
.expect("func should be defined");
assert_eq!(f.ty().params().collect::<Vec<_>>(), &[]);
assert_eq!(f.param_arity(), 0);
assert_eq!(f.ty().results().collect::<Vec<_>>(), &[]);
assert_eq!(f.result_arity(), 0);
let f = store
.get_host_func("", "f2")
.expect("func should be defined");
assert_eq!(f.ty().params().collect::<Vec<_>>(), &[]);
assert_eq!(f.ty().results().collect::<Vec<_>>(), &[ValType::I32]);
let f = store
.get_host_func("", "f3")
.expect("func should be defined");
assert_eq!(f.ty().params().collect::<Vec<_>>(), &[]);
assert_eq!(f.ty().results().collect::<Vec<_>>(), &[ValType::I64]);
let f = store
.get_host_func("", "f4")
.expect("func should be defined");
assert_eq!(f.ty().params().collect::<Vec<_>>(), &[]);
assert_eq!(f.ty().results().collect::<Vec<_>>(), &[ValType::F32]);
let f = store
.get_host_func("", "f5")
.expect("func should be defined");
assert_eq!(f.ty().params().collect::<Vec<_>>(), &[]);
assert_eq!(f.ty().results().collect::<Vec<_>>(), &[ValType::F64]);
let f = store
.get_host_func("", "f6")
.expect("func should be defined");
assert_eq!(
f.ty().params().collect::<Vec<_>>(),
&[
ValType::F32,
ValType::F64,
ValType::I32,
ValType::I64,
ValType::I32,
ValType::ExternRef,
ValType::FuncRef,
]
);
assert_eq!(f.ty().results().collect::<Vec<_>>(), &[ValType::F64]);
Ok(())
}
#[test]
// Note: Cranelift only supports refrerence types (used in the wasm in this
// test) on x64.
#[cfg(target_arch = "x86_64")]
fn import_works() -> Result<()> {
static HITS: AtomicUsize = AtomicUsize::new(0);
let wasm = wat::parse_str(
r#"
(import "" "f1" (func))
(import "" "f2" (func (param i32) (result i32)))
(import "" "f3" (func (param i32) (param i64)))
(import "" "f4" (func (param i32 i64 i32 f32 f64 externref funcref)))
(func (export "run") (param externref funcref)
call 0
i32.const 0
call 1
i32.const 1
i32.add
i64.const 3
call 2
i32.const 100
i64.const 200
i32.const 300
f32.const 400
f64.const 500
local.get 0
local.get 1
call 3
)
"#,
)?;
let mut config = Config::new();
config.wasm_reference_types(true);
config.wrap_host_func("", "f1", || {
assert_eq!(HITS.fetch_add(1, SeqCst), 0);
});
config.wrap_host_func("", "f2", |x: i32| -> i32 {
assert_eq!(x, 0);
assert_eq!(HITS.fetch_add(1, SeqCst), 1);
1
});
config.wrap_host_func("", "f3", |x: i32, y: i64| {
assert_eq!(x, 2);
assert_eq!(y, 3);
assert_eq!(HITS.fetch_add(1, SeqCst), 2);
});
config.wrap_host_func(
"",
"f4",
|a: i32, b: i64, c: i32, d: f32, e: f64, f: Option<ExternRef>, g: Option<Func>| {
assert_eq!(a, 100);
assert_eq!(b, 200);
assert_eq!(c, 300);
assert_eq!(d, 400.0);
assert_eq!(e, 500.0);
assert_eq!(
f.as_ref().unwrap().data().downcast_ref::<String>().unwrap(),
"hello"
);
assert_eq!(g.as_ref().unwrap().call(&[]).unwrap()[0].unwrap_i32(), 42);
assert_eq!(HITS.fetch_add(1, SeqCst), 3);
},
);
let engine = Engine::new(&config)?;
let module = Module::new(&engine, &wasm)?;
let store = Store::new(&engine);
let instance = Instance::new(
&store,
&module,
&[
store
.get_host_func("", "f1")
.expect("should be defined")
.into(),
store
.get_host_func("", "f2")
.expect("should be defined")
.into(),
store
.get_host_func("", "f3")
.expect("should be defined")
.into(),
store
.get_host_func("", "f4")
.expect("should be defined")
.into(),
],
)?;
let run = instance.get_func("run").unwrap();
run.call(&[
Val::ExternRef(Some(ExternRef::new("hello".to_string()))),
Val::FuncRef(Some(Func::wrap(&store, || -> i32 { 42 }))),
])?;
assert_eq!(HITS.load(SeqCst), 4);
Ok(())
}
#[test]
fn trap_smoke() -> Result<()> {
let mut config = Config::default();
config.wrap_host_func("", "", || -> Result<(), Trap> { Err(Trap::new("test")) });
let engine = Engine::new(&config)?;
let store = Store::new(&engine);
let f = store.get_host_func("", "").expect("should be defined");
let err = f.call(&[]).unwrap_err().downcast::<Trap>()?;
assert!(err.to_string().contains("test"));
assert!(err.i32_exit_status().is_none());
Ok(())
}
#[test]
fn trap_import() -> Result<()> {
let wasm = wat::parse_str(
r#"
(import "" "" (func))
(start 0)
"#,
)?;
let mut config = Config::default();
config.wrap_host_func("", "", || -> Result<(), Trap> { Err(Trap::new("foo")) });
let engine = Engine::new(&config)?;
let module = Module::new(&engine, &wasm)?;
let store = Store::new(&engine);
let trap = Instance::new(
&store,
&module,
&[store.get_host_func("", "").expect("defined").into()],
)
.err()
.unwrap()
.downcast::<Trap>()?;
assert!(trap.to_string().contains("foo"));
Ok(())
}
#[test]
fn new_from_signature() -> Result<()> {
let mut config = Config::default();
let ty = FuncType::new(None, None);
config.define_host_func("", "f1", ty, |_, _, _| panic!());
let ty = FuncType::new(Some(ValType::I32), Some(ValType::F64));
config.define_host_func("", "f2", ty, |_, _, _| panic!());
let engine = Engine::new(&config)?;
let store = Store::new(&engine);
let f = store.get_host_func("", "f1").expect("func defined");
assert!(f.typed::<(), ()>().is_ok());
assert!(f.typed::<(), i32>().is_err());
assert!(f.typed::<i32, ()>().is_err());
let f = store.get_host_func("", "f2").expect("func defined");
assert!(f.typed::<(), ()>().is_err());
assert!(f.typed::<(), i32>().is_err());
assert!(f.typed::<i32, ()>().is_err());
assert!(f.typed::<i32, f64>().is_ok());
Ok(())
}
#[test]
fn call_wrapped_func() -> Result<()> {
let mut config = Config::default();
config.wrap_host_func("", "f1", |a: i32, b: i64, c: f32, d: f64| {
assert_eq!(a, 1);
assert_eq!(b, 2);
assert_eq!(c, 3.0);
assert_eq!(d, 4.0);
});
config.wrap_host_func("", "f2", || 1i32);
config.wrap_host_func("", "f3", || 2i64);
config.wrap_host_func("", "f4", || 3.0f32);
config.wrap_host_func("", "f5", || 4.0f64);
let engine = Engine::new(&config)?;
let store = Store::new(&engine);
let f = store.get_host_func("", "f1").expect("func defined");
f.call(&[Val::I32(1), Val::I64(2), 3.0f32.into(), 4.0f64.into()])?;
f.typed::<(i32, i64, f32, f64), ()>()?
.call((1, 2, 3.0, 4.0))?;
let f = store.get_host_func("", "f2").expect("func defined");
let results = f.call(&[])?;
assert_eq!(results.len(), 1);
assert_eq!(results[0].unwrap_i32(), 1);
assert_eq!(f.typed::<(), i32>()?.call(())?, 1);
let f = store.get_host_func("", "f3").expect("func defined");
let results = f.call(&[])?;
assert_eq!(results.len(), 1);
assert_eq!(results[0].unwrap_i64(), 2);
assert_eq!(f.typed::<(), i64>()?.call(())?, 2);
let f = store.get_host_func("", "f4").expect("func defined");
let results = f.call(&[])?;
assert_eq!(results.len(), 1);
assert_eq!(results[0].unwrap_f32(), 3.0);
assert_eq!(f.typed::<(), f32>()?.call(())?, 3.0);
let f = store.get_host_func("", "f5").expect("func defined");
let results = f.call(&[])?;
assert_eq!(results.len(), 1);
assert_eq!(results[0].unwrap_f64(), 4.0);
assert_eq!(f.typed::<(), f64>()?.call(())?, 4.0);
Ok(())
}
#[test]
fn func_return_nothing() -> Result<()> {
let mut config = Config::default();
let ty = FuncType::new(None, Some(ValType::I32));
config.define_host_func("", "", ty, |_, _, _| Ok(()));
let engine = Engine::new(&config)?;
let store = Store::new(&engine);
let f = store.get_host_func("", "").expect("func defined");
let err = f.call(&[]).unwrap_err().downcast::<Trap>()?;
assert!(err
.to_string()
.contains("function attempted to return an incompatible value"));
Ok(())
}
#[test]
fn call_via_funcref() -> Result<()> {
static HITS: AtomicUsize = AtomicUsize::new(0);
struct A;
impl Drop for A {
fn drop(&mut self) {
HITS.fetch_add(1, SeqCst);
}
}
let wasm = wat::parse_str(
r#"
(table $t 1 funcref)
(type $add (func (param i32 i32) (result i32)))
(func (export "call") (param funcref) (result i32 funcref)
(table.set $t (i32.const 0) (local.get 0))
(call_indirect (type $add) (i32.const 3) (i32.const 4) (i32.const 0))
(local.get 0)
)
"#,
)?;
let mut config = Config::default();
let a = A;
config.wrap_host_func("", "", move |x: i32, y: i32| {
drop(&a);
x + y
});
let engine = Engine::new(&config)?;
let module = Module::new(&engine, &wasm)?;
let store = Store::new(&engine);
let instance = Instance::new(&store, &module, &[])?;
let results = instance
.get_func("call")
.unwrap()
.call(&[store.get_host_func("", "").expect("func defined").into()])?;
assert_eq!(results.len(), 2);
assert_eq!(results[0].unwrap_i32(), 7);
{
let f = results[1].unwrap_funcref().unwrap();
let results = f.call(&[1.into(), 2.into()])?;
assert_eq!(results.len(), 1);
assert_eq!(results[0].unwrap_i32(), 3);
}
assert_eq!(HITS.load(SeqCst), 0);
drop((results, instance, store, module, engine));
assert_eq!(HITS.load(SeqCst), 0);
drop(config);
assert_eq!(HITS.load(SeqCst), 1);
Ok(())
}
#[test]
fn store_with_context() -> Result<()> {
struct Ctx {
called: std::cell::Cell<bool>,
}
let mut config = Config::default();
config.wrap_host_func("", "", |caller: Caller| {
let ctx = caller
.store()
.get::<Ctx>()
.expect("store should have context");
ctx.called.set(true);
});
let engine = Engine::new(&config)?;
let store = Store::new(&engine);
assert!(store.get::<Ctx>().is_none());
assert!(store
.set(Ctx {
called: std::cell::Cell::new(false)
})
.is_ok());
assert!(store
.set(Ctx {
called: std::cell::Cell::new(false)
})
.is_err());
assert!(!store.get::<Ctx>().unwrap().called.get());
let f = store.get_host_func("", "").expect("func defined");
f.call(&[])?;
assert!(store.get::<Ctx>().unwrap().called.get());
Ok(())
}
#[test]
fn wasi_imports_missing_context() -> Result<()> {
let mut config = Config::default();
Wasi::add_to_config(&mut config);
let wasm = wat::parse_str(
r#"
(import "wasi_snapshot_preview1" "proc_exit" (func $__wasi_proc_exit (param i32)))
(memory (export "memory") 0)
(func (export "_start")
(call $__wasi_proc_exit (i32.const 123))
)
"#,
)?;
let engine = Engine::new(&config)?;
let module = Module::new(&engine, wasm)?;
let store = Store::new(&engine);
let linker = Linker::new(&store);
let instance = linker.instantiate(&module)?;
let start = instance.get_typed_func::<(), ()>("_start")?;
let trap = start.call(()).unwrap_err();
assert!(trap.to_string().contains("context is missing in the store"));
assert!(trap.i32_exit_status().is_none());
Ok(())
}
#[test]
fn wasi_imports() -> Result<()> {
let mut config = Config::default();
Wasi::add_to_config(&mut config);
let wasm = wat::parse_str(
r#"
(import "wasi_snapshot_preview1" "proc_exit" (func $__wasi_proc_exit (param i32)))
(memory (export "memory") 0)
(func (export "_start")
(call $__wasi_proc_exit (i32.const 123))
)
"#,
)?;
let engine = Engine::new(&config)?;
let module = Module::new(&engine, wasm)?;
let store = Store::new(&engine);
assert!(Wasi::set_context(&store, WasiCtxBuilder::new().build()?).is_ok());
let linker = Linker::new(&store);
let instance = linker.instantiate(&module)?;
let start = instance.get_typed_func::<(), ()>("_start")?;
let trap = start.call(()).unwrap_err();
assert_eq!(trap.i32_exit_status(), Some(123));
Ok(())
}
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