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6e6713ae0b0be578221a2802719327526458a8cf
wasmtime/tests/all/externals.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 wasmtime::*;
#[test]
fn bad_globals() {
let ty = GlobalType::new(ValType::I32, Mutability::Var);
assert!(Global::new(&Store::default(), ty.clone(), Val::I64(0)).is_err());
assert!(Global::new(&Store::default(), ty.clone(), Val::F32(0)).is_err());
assert!(Global::new(&Store::default(), ty.clone(), Val::F64(0)).is_err());
let ty = GlobalType::new(ValType::I32, Mutability::Const);
let g = Global::new(&Store::default(), ty.clone(), Val::I32(0)).unwrap();
assert!(g.set(Val::I32(1)).is_err());
let ty = GlobalType::new(ValType::I32, Mutability::Var);
let g = Global::new(&Store::default(), ty.clone(), Val::I32(0)).unwrap();
assert!(g.set(Val::I64(0)).is_err());
}
#[test]
fn bad_tables() {
// i32 not supported yet
let ty = TableType::new(ValType::I32, Limits::new(0, Some(1)));
assert!(Table::new(&Store::default(), ty.clone(), Val::I32(0)).is_err());
// mismatched initializer
let ty = TableType::new(ValType::FuncRef, Limits::new(0, Some(1)));
assert!(Table::new(&Store::default(), ty.clone(), Val::I32(0)).is_err());
// get out of bounds
let ty = TableType::new(ValType::FuncRef, Limits::new(0, Some(1)));
let t = Table::new(&Store::default(), ty.clone(), Val::FuncRef(None)).unwrap();
assert!(t.get(0).is_none());
assert!(t.get(u32::max_value()).is_none());
// set out of bounds or wrong type
let ty = TableType::new(ValType::FuncRef, Limits::new(1, Some(1)));
let t = Table::new(&Store::default(), ty.clone(), Val::FuncRef(None)).unwrap();
assert!(t.set(0, Val::I32(0)).is_err());
assert!(t.set(0, Val::FuncRef(None)).is_ok());
assert!(t.set(1, Val::FuncRef(None)).is_err());
// grow beyond max
let ty = TableType::new(ValType::FuncRef, Limits::new(1, Some(1)));
let t = Table::new(&Store::default(), ty.clone(), Val::FuncRef(None)).unwrap();
assert!(t.grow(0, Val::FuncRef(None)).is_ok());
assert!(t.grow(1, Val::FuncRef(None)).is_err());
assert_eq!(t.size(), 1);
// grow wrong type
let ty = TableType::new(ValType::FuncRef, Limits::new(1, Some(2)));
let t = Table::new(&Store::default(), ty.clone(), Val::FuncRef(None)).unwrap();
assert!(t.grow(1, Val::I32(0)).is_err());
assert_eq!(t.size(), 1);
}
#[test]
fn cross_store() -> anyhow::Result<()> {
let mut cfg = Config::new();
cfg.wasm_reference_types(true);
let engine = Engine::new(&cfg)?;
let store1 = Store::new(&engine);
let store2 = Store::new(&engine);
// ============ Cross-store instantiation ==============
let func = Func::wrap(&store2, || {});
let ty = GlobalType::new(ValType::I32, Mutability::Const);
let global = Global::new(&store2, ty, Val::I32(0))?;
let ty = MemoryType::new(Limits::new(1, None));
let memory = Memory::new(&store2, ty);
let ty = TableType::new(ValType::FuncRef, Limits::new(1, None));
let table = Table::new(&store2, ty, Val::FuncRef(None))?;
let need_func = Module::new(&engine, r#"(module (import "" "" (func)))"#)?;
assert!(Instance::new(&store1, &need_func, &[func.into()]).is_err());
let need_global = Module::new(&engine, r#"(module (import "" "" (global i32)))"#)?;
assert!(Instance::new(&store1, &need_global, &[global.into()]).is_err());
let need_table = Module::new(&engine, r#"(module (import "" "" (table 1 funcref)))"#)?;
assert!(Instance::new(&store1, &need_table, &[table.into()]).is_err());
let need_memory = Module::new(&engine, r#"(module (import "" "" (memory 1)))"#)?;
assert!(Instance::new(&store1, &need_memory, &[memory.into()]).is_err());
// ============ Cross-store globals ==============
let store1val = Val::FuncRef(Some(Func::wrap(&store1, || {})));
let store2val = Val::FuncRef(Some(Func::wrap(&store2, || {})));
let ty = GlobalType::new(ValType::FuncRef, Mutability::Var);
assert!(Global::new(&store2, ty.clone(), store1val.clone()).is_err());
if let Ok(g) = Global::new(&store2, ty.clone(), store2val.clone()) {
assert!(g.set(store1val.clone()).is_err());
}
// ============ Cross-store tables ==============
let ty = TableType::new(ValType::FuncRef, Limits::new(1, None));
assert!(Table::new(&store2, ty.clone(), store1val.clone()).is_err());
let t1 = Table::new(&store2, ty.clone(), store2val.clone())?;
assert!(t1.set(0, store1val.clone()).is_err());
assert!(t1.grow(0, store1val.clone()).is_err());
assert!(t1.fill(0, store1val.clone(), 1).is_err());
let t2 = Table::new(&store1, ty.clone(), store1val.clone())?;
assert!(Table::copy(&t1, 0, &t2, 0, 0).is_err());
// ============ Cross-store funcs ==============
let module = Module::new(&engine, r#"(module (func (export "f") (param funcref)))"#)?;
let s1_inst = Instance::new(&store1, &module, &[])?;
let s2_inst = Instance::new(&store2, &module, &[])?;
let s1_f = s1_inst.get_func("f").unwrap();
let s2_f = s2_inst.get_func("f").unwrap();
assert!(s1_f.call(&[Val::FuncRef(None)]).is_ok());
assert!(s2_f.call(&[Val::FuncRef(None)]).is_ok());
assert!(s1_f.call(&[Val::FuncRef(Some(s1_f.clone()))]).is_ok());
assert!(s1_f.call(&[Val::FuncRef(Some(s2_f.clone()))]).is_err());
assert!(s2_f.call(&[Val::FuncRef(Some(s1_f.clone()))]).is_err());
assert!(s2_f.call(&[Val::FuncRef(Some(s2_f.clone()))]).is_ok());
let s1_f_t = s1_f.typed::<Option<Func>, ()>()?;
let s2_f_t = s2_f.typed::<Option<Func>, ()>()?;
assert!(s1_f_t.call(None).is_ok());
assert!(s2_f_t.call(None).is_ok());
assert!(s1_f_t.call(Some(s1_f.clone())).is_ok());
assert!(s1_f_t.call(Some(s2_f.clone())).is_err());
assert!(s2_f_t.call(Some(s1_f.clone())).is_err());
assert!(s2_f_t.call(Some(s2_f.clone())).is_ok());
Ok(())
}
#[test]
fn get_set_externref_globals_via_api() -> anyhow::Result<()> {
let mut cfg = Config::new();
cfg.wasm_reference_types(true);
let engine = Engine::new(&cfg)?;
let store = Store::new(&engine);
// Initialize with a null externref.
let global = Global::new(
&store,
GlobalType::new(ValType::ExternRef, Mutability::Var),
Val::ExternRef(None),
)?;
assert!(global.get().unwrap_externref().is_none());
global.set(Val::ExternRef(Some(ExternRef::new("hello".to_string()))))?;
let r = global.get().unwrap_externref().unwrap();
assert!(r.data().is::<String>());
assert_eq!(r.data().downcast_ref::<String>().unwrap(), "hello");
// Initialize with a non-null externref.
let global = Global::new(
&store,
GlobalType::new(ValType::ExternRef, Mutability::Const),
Val::ExternRef(Some(ExternRef::new(42_i32))),
)?;
let r = global.get().unwrap_externref().unwrap();
assert!(r.data().is::<i32>());
assert_eq!(r.data().downcast_ref::<i32>().copied().unwrap(), 42);
Ok(())
}
#[test]
fn get_set_funcref_globals_via_api() -> anyhow::Result<()> {
let mut cfg = Config::new();
cfg.wasm_reference_types(true);
let engine = Engine::new(&cfg)?;
let store = Store::new(&engine);
let f = Func::wrap(&store, || {});
// Initialize with a null funcref.
let global = Global::new(
&store,
GlobalType::new(ValType::FuncRef, Mutability::Var),
Val::FuncRef(None),
)?;
assert!(global.get().unwrap_funcref().is_none());
global.set(Val::FuncRef(Some(f.clone())))?;
let f2 = global.get().unwrap_funcref().cloned().unwrap();
assert_eq!(f.ty(), f2.ty());
// Initialize with a non-null funcref.
let global = Global::new(
&store,
GlobalType::new(ValType::FuncRef, Mutability::Var),
Val::FuncRef(Some(f.clone())),
)?;
let f2 = global.get().unwrap_funcref().cloned().unwrap();
assert_eq!(f.ty(), f2.ty());
Ok(())
}
#[test]
fn create_get_set_funcref_tables_via_api() -> anyhow::Result<()> {
let mut cfg = Config::new();
cfg.wasm_reference_types(true);
let engine = Engine::new(&cfg)?;
let store = Store::new(&engine);
let table_ty = TableType::new(ValType::FuncRef, Limits::at_least(10));
let table = Table::new(
&store,
table_ty,
Val::FuncRef(Some(Func::wrap(&store, || {}))),
)?;
assert!(table.get(5).unwrap().unwrap_funcref().is_some());
table.set(5, Val::FuncRef(None))?;
assert!(table.get(5).unwrap().unwrap_funcref().is_none());
Ok(())
}
#[test]
fn fill_funcref_tables_via_api() -> anyhow::Result<()> {
let mut cfg = Config::new();
cfg.wasm_reference_types(true);
let engine = Engine::new(&cfg)?;
let store = Store::new(&engine);
let table_ty = TableType::new(ValType::FuncRef, Limits::at_least(10));
let table = Table::new(&store, table_ty, Val::FuncRef(None))?;
for i in 0..10 {
assert!(table.get(i).unwrap().unwrap_funcref().is_none());
}
table.fill(2, Val::FuncRef(Some(Func::wrap(&store, || {}))), 4)?;
for i in (0..2).chain(7..10) {
assert!(table.get(i).unwrap().unwrap_funcref().is_none());
}
for i in 2..6 {
assert!(table.get(i).unwrap().unwrap_funcref().is_some());
}
Ok(())
}
#[test]
fn grow_funcref_tables_via_api() -> anyhow::Result<()> {
let mut cfg = Config::new();
cfg.wasm_reference_types(true);
let engine = Engine::new(&cfg)?;
let store = Store::new(&engine);
let table_ty = TableType::new(ValType::FuncRef, Limits::at_least(10));
let table = Table::new(&store, table_ty, Val::FuncRef(None))?;
assert_eq!(table.size(), 10);
table.grow(3, Val::FuncRef(None))?;
assert_eq!(table.size(), 13);
Ok(())
}
#[test]
fn create_get_set_externref_tables_via_api() -> anyhow::Result<()> {
let mut cfg = Config::new();
cfg.wasm_reference_types(true);
let engine = Engine::new(&cfg)?;
let store = Store::new(&engine);
let table_ty = TableType::new(ValType::ExternRef, Limits::at_least(10));
let table = Table::new(
&store,
table_ty,
Val::ExternRef(Some(ExternRef::new(42_usize))),
)?;
assert_eq!(
*table
.get(5)
.unwrap()
.unwrap_externref()
.unwrap()
.data()
.downcast_ref::<usize>()
.unwrap(),
42
);
table.set(5, Val::ExternRef(None))?;
assert!(table.get(5).unwrap().unwrap_externref().is_none());
Ok(())
}
#[test]
fn fill_externref_tables_via_api() -> anyhow::Result<()> {
let mut cfg = Config::new();
cfg.wasm_reference_types(true);
let engine = Engine::new(&cfg)?;
let store = Store::new(&engine);
let table_ty = TableType::new(ValType::ExternRef, Limits::at_least(10));
let table = Table::new(&store, table_ty, Val::ExternRef(None))?;
for i in 0..10 {
assert!(table.get(i).unwrap().unwrap_externref().is_none());
}
table.fill(2, Val::ExternRef(Some(ExternRef::new(42_usize))), 4)?;
for i in (0..2).chain(7..10) {
assert!(table.get(i).unwrap().unwrap_externref().is_none());
}
for i in 2..6 {
assert_eq!(
*table
.get(i)
.unwrap()
.unwrap_externref()
.unwrap()
.data()
.downcast_ref::<usize>()
.unwrap(),
42
);
}
Ok(())
}
#[test]
fn grow_externref_tables_via_api() -> anyhow::Result<()> {
let mut cfg = Config::new();
cfg.wasm_reference_types(true);
let engine = Engine::new(&cfg)?;
let store = Store::new(&engine);
let table_ty = TableType::new(ValType::ExternRef, Limits::at_least(10));
let table = Table::new(&store, table_ty, Val::ExternRef(None))?;
assert_eq!(table.size(), 10);
table.grow(3, Val::ExternRef(None))?;
assert_eq!(table.size(), 13);
Ok(())
}
#[test]
fn read_write_memory_via_api() {
let cfg = Config::new();
let store = Store::new(&Engine::new(&cfg).unwrap());
let ty = MemoryType::new(Limits::new(1, None));
let mem = Memory::new(&store, ty);
mem.grow(1).unwrap();
let value = b"hello wasm";
mem.write(mem.data_size() - value.len(), value).unwrap();
let mut buffer = [0u8; 10];
mem.read(mem.data_size() - buffer.len(), &mut buffer)
.unwrap();
assert_eq!(value, &buffer);
// Error conditions.
// Out of bounds write.
let res = mem.write(mem.data_size() - value.len() + 1, value);
assert!(res.is_err());
assert_ne!(
unsafe { mem.data_unchecked()[mem.data_size() - value.len() + 1] },
value[0],
"no data is written",
);
// Out of bounds read.
buffer[0] = 0x42;
let res = mem.read(mem.data_size() - buffer.len() + 1, &mut buffer);
assert!(res.is_err());
assert_eq!(buffer[0], 0x42, "no data is read");
// Read offset overflow.
let res = mem.read(usize::MAX, &mut buffer);
assert!(res.is_err());
// Write offset overflow.
let res = mem.write(usize::MAX, &mut buffer);
assert!(res.is_err());
}
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