Implement RFC 11: Redesigning Wasmtime's APIs (#2897)

Implement Wasmtime's new API as designed by RFC 11. This is quite a large commit which has had lots of discussion externally, so for more information it's best to read the RFC thread and the PR thread.

crates/wasi/src/lib.rs

@@ -28,7 +28,7 @@ pub use sync::*;
 #[cfg(feature = "tokio")]
 pub mod tokio {
     pub use wasi_tokio::*;
-    super::define_wasi!(async);
+    super::define_wasi!(async T: Send);
 }
 
 // The only difference between these definitions for sync vs async is whether
@@ -38,100 +38,41 @@ pub mod tokio {
 #[doc(hidden)]
 #[macro_export]
 macro_rules! define_wasi {
-    ($async_mode: tt) => {
+    ($async_mode:tt $($bounds:tt)*) => {
 
-use std::cell::RefCell;
-use std::rc::Rc;
-use wasmtime::{Config, Linker, Store};
-use wasi_common::WasiCtx;
+use wasmtime::Linker;
 
-/// An instantiated instance of all available wasi exports. Presently includes
-/// both the "preview1" snapshot and the "unstable" (preview0) snapshot.
-pub struct Wasi {
-    preview_1: snapshots::preview_1::Wasi,
-    preview_0: snapshots::preview_0::Wasi,
-}
-
-impl Wasi {
-    pub fn new(store: &Store, context: WasiCtx) -> Self {
-        let context = Rc::new(RefCell::new(context));
-        let preview_1 = snapshots::preview_1::Wasi::new(store, context.clone());
-        let preview_0 = snapshots::preview_0::Wasi::new(store, context);
-        Self {
-            preview_1,
-            preview_0,
-        }
-    }
-    pub fn add_to_linker(&self, linker: &mut Linker) -> Result<(), anyhow::Error> {
-        self.preview_1.add_to_linker(linker)?;
-        self.preview_0.add_to_linker(linker)?;
-        Ok(())
-    }
-    pub fn add_to_config(config: &mut Config) {
-        snapshots::preview_1::Wasi::add_to_config(config);
-        snapshots::preview_0::Wasi::add_to_config(config);
-    }
-    pub fn set_context(store: &Store, context: WasiCtx) -> Result<(), WasiCtx> {
-        // It doesn't matter which underlying `Wasi` type this gets called on as the
-        // implementations are identical
-        snapshots::preview_1::Wasi::set_context(store, context)
-    }
+pub fn add_to_linker<T>(
+    linker: &mut Linker<T>,
+    get_cx: impl Fn(&mut T) -> &mut crate::WasiCtx + Send + Sync + Copy + 'static,
+) -> anyhow::Result<()>
+    where $($bounds)*
+{
+    snapshots::preview_1::add_wasi_snapshot_preview1_to_linker(linker, get_cx)?;
+    snapshots::preview_0::add_wasi_unstable_to_linker(linker, get_cx)?;
+    Ok(())
 }
 
 pub mod snapshots {
     pub mod preview_1 {
-        use wasi_common::WasiCtx;
-        // Defines a `struct Wasi` with member fields and appropriate APIs for dealing
-        // with all the various WASI exports.
-        wasmtime_wiggle::wasmtime_integration!({
+        wiggle::wasmtime_integration!({
             // The wiggle code to integrate with lives here:
             target: wasi_common::snapshots::preview_1,
             // This must be the same witx document as used above. This should be ensured by
             // the `WASI_ROOT` env variable, which is set in wasi-common's `build.rs`.
             witx: ["$WASI_ROOT/phases/snapshot/witx/wasi_snapshot_preview1.witx"],
-            // This must be the same ctx type as used for the target:
-            ctx: WasiCtx,
-            // This macro will emit a struct to represent the instance,
-            // with this name and docs:
-            modules: { wasi_snapshot_preview1 =>
-                { name: Wasi,
-                  docs: "An instantiated instance of the wasi exports.
-
-This represents a wasi module which can be used to instantiate other wasm
-modules. This structure exports all that various fields of the wasi instance
-as fields which can be used to implement your own instantiation logic, if
-necessary. Additionally [`Wasi::get_export`] can be used to do name-based
-resolution.",
-                },
-            },
+            errors: { errno => Error },
             $async_mode: *
         });
     }
     pub mod preview_0 {
-        use wasi_common::WasiCtx;
-        // Defines a `struct Wasi` with member fields and appropriate APIs for dealing
-        // with all the various WASI exports.
-        wasmtime_wiggle::wasmtime_integration!({
+        wiggle::wasmtime_integration!({
             // The wiggle code to integrate with lives here:
             target: wasi_common::snapshots::preview_0,
             // This must be the same witx document as used above. This should be ensured by
             // the `WASI_ROOT` env variable, which is set in wasi-common's `build.rs`.
             witx: ["$WASI_ROOT/phases/old/snapshot_0/witx/wasi_unstable.witx"],
-            // This must be the same ctx type as used for the target:
-            ctx: WasiCtx,
-            // This macro will emit a struct to represent the instance,
-            // with this name and docs:
-            modules: { wasi_unstable =>
-                { name: Wasi,
-                  docs: "An instantiated instance of the wasi exports.
-
-This represents a wasi module which can be used to instantiate other wasm
-modules. This structure exports all that various fields of the wasi instance
-as fields which can be used to implement your own instantiation logic, if
-necessary. Additionally [`Wasi::get_export`] can be used to do name-based
-resolution.",
-                },
-            },
+            errors: { errno => Error },
             $async_mode: *
         });
     }