Remove the Context type from wasmtime (#825)

* Remove the `Context` type from `wasmtime`

This hasn't really ended up being used in all that many places and the
dependencies on it were pretty minimal. This commit removes it in favor
of simplifying its various users a bit and/or leveraging the
`Engine`/`Store` structures where possible.

* Run rustfmt

crates/api/src/callable.rs

@@ -141,8 +141,7 @@ impl WrappedCallable for WasmtimeFn {
         // Get the trampoline to call for this function.
         let exec_code_buf = self
             .store
-            .context()
-            .compiler()
+            .compiler_mut()
             .get_published_trampoline(body, &signature, value_size)
             .map_err(|e| Trap::new(format!("trampoline error: {:?}", e)))?;
 

crates/api/src/context.rs

@@ -1,53 +0,0 @@
-use crate::Config;
-use std::cell::{RefCell, RefMut};
-use std::hash::{Hash, Hasher};
-use std::rc::Rc;
-use wasmtime_environ::settings;
-use wasmtime_jit::{native, Compiler, Features};
-
-#[derive(Clone)]
-pub struct Context {
-    compiler: Rc<RefCell<Compiler>>,
-    features: Features,
-    debug_info: bool,
-}
-
-impl Context {
-    pub fn new(config: &Config) -> Context {
-        let isa = native::builder().finish(settings::Flags::new(config.flags.clone()));
-        Context::new_with_compiler(config, Compiler::new(isa, config.strategy))
-    }
-
-    pub fn new_with_compiler(config: &Config, compiler: Compiler) -> Context {
-        Context {
-            compiler: Rc::new(RefCell::new(compiler)),
-            features: config.features.clone(),
-            debug_info: config.debug_info,
-        }
-    }
-
-    pub(crate) fn debug_info(&self) -> bool {
-        self.debug_info
-    }
-
-    pub(crate) fn compiler(&self) -> RefMut<Compiler> {
-        self.compiler.borrow_mut()
-    }
-}
-
-impl Hash for Context {
-    fn hash<H>(&self, state: &mut H)
-    where
-        H: Hasher,
-    {
-        self.compiler.as_ptr().hash(state)
-    }
-}
-
-impl Eq for Context {}
-
-impl PartialEq for Context {
-    fn eq(&self, other: &Context) -> bool {
-        Rc::ptr_eq(&self.compiler, &other.compiler)
-    }
-}

crates/api/src/instance.rs

@@ -1,4 +1,3 @@
-use crate::context::Context;
 use crate::externals::Extern;
 use crate::module::Module;
 use crate::runtime::Store;
@@ -6,9 +5,6 @@ use crate::trampoline::take_api_trap;
 use crate::trap::Trap;
 use crate::types::{ExportType, ExternType};
 use anyhow::{Error, Result};
-use std::cell::RefCell;
-use std::collections::{HashMap, HashSet};
-use std::rc::Rc;
 use wasmtime_jit::{CompiledModule, Resolver};
 use wasmtime_runtime::{Export, InstanceHandle, InstantiationError};
 
@@ -29,19 +25,15 @@ fn instantiate_in_context(
     data: &[u8],
     imports: &[Extern],
     module_name: Option<&str>,
-    context: Context,
-    exports: Rc<RefCell<HashMap<String, Option<wasmtime_runtime::Export>>>>,
-) -> Result<(InstanceHandle, HashSet<Context>), Error> {
-    let mut contexts = HashSet::new();
-    let debug_info = context.debug_info();
+) -> Result<InstanceHandle> {
     let mut resolver = SimpleResolver { imports };
     let mut compiled_module = CompiledModule::new(
-        &mut context.compiler(),
+        &mut store.compiler_mut(),
         data,
         module_name,
         &mut resolver,
-        exports,
-        debug_info,
+        store.global_exports().clone(),
+        store.engine().config().debug_info,
     )?;
 
     // Register all module signatures
@@ -58,34 +50,24 @@ fn instantiate_in_context(
             e.into()
         }
     })?;
-    contexts.insert(context);
-    Ok((instance, contexts))
+    Ok(instance)
 }
 
 #[derive(Clone)]
 pub struct Instance {
     instance_handle: InstanceHandle,
-
     module: Module,
-
-    // We need to keep CodeMemory alive.
-    contexts: HashSet<Context>,
-
     exports: Box<[Extern]>,
 }
 
 impl Instance {
     pub fn new(module: &Module, externs: &[Extern]) -> Result<Instance, Error> {
         let store = module.store();
-        let context = store.context().clone();
-        let exports = store.global_exports().clone();
-        let (mut instance_handle, contexts) = instantiate_in_context(
-            module.store(),
+        let mut instance_handle = instantiate_in_context(
+            store,
             module.binary().expect("binary"),
             externs,
             module.name(),
-            context,
-            exports,
         )?;
 
         let exports = {
@@ -104,7 +86,6 @@ impl Instance {
         Ok(Instance {
             instance_handle,
             module: module.clone(),
-            contexts,
             exports,
         })
     }
@@ -141,8 +122,6 @@ impl Instance {
     }
 
     pub fn from_handle(store: &Store, instance_handle: InstanceHandle) -> Instance {
-        let contexts = HashSet::new();
-
         let mut exports = Vec::new();
         let mut exports_types = Vec::new();
         let mut mutable = instance_handle.clone();
@@ -175,7 +154,6 @@ impl Instance {
         Instance {
             instance_handle,
             module,
-            contexts,
             exports: exports.into_boxed_slice(),
         }
     }

crates/api/src/lib.rs

@@ -7,7 +7,6 @@
 //! itself for consumption from other languages.
 
 mod callable;
-mod context;
 mod externals;
 mod instance;
 mod module;

crates/api/src/module.rs

@@ -196,7 +196,7 @@ impl Module {
     ///
     /// [binary]: https://webassembly.github.io/spec/core/binary/index.html
     pub fn validate(store: &Store, binary: &[u8]) -> Result<()> {
-        let features = store.engine().config.features.clone();
+        let features = store.engine().config().features.clone();
         let config = ValidatingParserConfig {
             operator_config: OperatorValidatorConfig {
                 enable_threads: features.threads,

crates/api/src/runtime.rs

@@ -1,4 +1,3 @@
-use crate::context::Context;
 use anyhow::Result;
 use std::cell::RefCell;
 use std::collections::HashMap;
@@ -8,7 +7,7 @@ use wasmtime_environ::{
     ir,
     settings::{self, Configurable},
 };
-use wasmtime_jit::{CompilationStrategy, Features};
+use wasmtime_jit::{native, CompilationStrategy, Compiler, Features};
 
 // Runtime Environment
 
@@ -297,7 +296,7 @@ pub enum OptLevel {
 /// default settings.
 #[derive(Default, Clone)]
 pub struct Engine {
-    pub(crate) config: Arc<Config>,
+    config: Arc<Config>,
 }
 
 impl Engine {
@@ -308,6 +307,11 @@ impl Engine {
             config: Arc::new(config.clone()),
         }
     }
+
+    /// Returns the configuration settings that this engine is using.
+    pub fn config(&self) -> &Config {
+        &self.config
+    }
 }
 
 // Store
@@ -337,7 +341,7 @@ pub struct Store {
 
 struct StoreInner {
     engine: Engine,
-    context: Context,
+    compiler: RefCell<Compiler>,
     global_exports: Rc<RefCell<HashMap<String, Option<wasmtime_runtime::Export>>>>,
     signature_cache: RefCell<HashMap<wasmtime_runtime::VMSharedSignatureIndex, ir::Signature>>,
 }
@@ -345,10 +349,12 @@ struct StoreInner {
 impl Store {
     /// Creates a new store to be associated with the given [`Engine`].
     pub fn new(engine: &Engine) -> Store {
+        let isa = native::builder().finish(settings::Flags::new(engine.config.flags.clone()));
+        let compiler = Compiler::new(isa, engine.config.strategy);
         Store {
             inner: Rc::new(StoreInner {
                 engine: engine.clone(),
-                context: Context::new(&engine.config),
+                compiler: RefCell::new(compiler),
                 global_exports: Rc::new(RefCell::new(HashMap::new())),
                 signature_cache: RefCell::new(HashMap::new()),
             }),
@@ -360,8 +366,8 @@ impl Store {
         &self.inner.engine
     }
 
-    pub(crate) fn context(&self) -> &Context {
-        &self.inner.context
+    pub(crate) fn compiler_mut(&self) -> std::cell::RefMut<'_, Compiler> {
+        self.inner.compiler.borrow_mut()
     }
 
     // Specific to wasmtime: hack to pass memory around to wasi
@@ -377,7 +383,7 @@ impl Store {
         signature: &ir::Signature,
     ) -> wasmtime_runtime::VMSharedSignatureIndex {
         use std::collections::hash_map::Entry;
-        let index = self.context().compiler().signatures().register(signature);
+        let index = self.compiler_mut().signatures().register(signature);
         match self.inner.signature_cache.borrow_mut().entry(index) {
             Entry::Vacant(v) => {
                 v.insert(signature.clone());