Merge pull request #3738 from cfallin/pooling-affinity

Pooling allocator: add a reuse-affinity policy.

crates/wasmtime/src/config/pooling.rs

@@ -249,6 +249,10 @@ pub enum PoolingAllocationStrategy {
     NextAvailable,
     /// Allocate from a random available instance.
     Random,
+    /// Try to allocate an instance slot that was previously used for
+    /// the same module, potentially enabling faster instantiation by
+    /// reusing e.g. memory mappings.
+    ReuseAffinity,
 }
 
 impl Default for PoolingAllocationStrategy {
@@ -256,6 +260,7 @@ impl Default for PoolingAllocationStrategy {
         match wasmtime_runtime::PoolingAllocationStrategy::default() {
             wasmtime_runtime::PoolingAllocationStrategy::NextAvailable => Self::NextAvailable,
             wasmtime_runtime::PoolingAllocationStrategy::Random => Self::Random,
+            wasmtime_runtime::PoolingAllocationStrategy::ReuseAffinity => Self::ReuseAffinity,
         }
     }
 }
@@ -268,6 +273,7 @@ impl Into<wasmtime_runtime::PoolingAllocationStrategy> for PoolingAllocationStra
         match self {
             Self::NextAvailable => wasmtime_runtime::PoolingAllocationStrategy::NextAvailable,
             Self::Random => wasmtime_runtime::PoolingAllocationStrategy::Random,
+            Self::ReuseAffinity => wasmtime_runtime::PoolingAllocationStrategy::ReuseAffinity,
         }
     }
 }

crates/wasmtime/src/instance.rs

@@ -707,6 +707,7 @@ impl<'a> Instantiator<'a> {
                     .allocator()
                     .allocate(InstanceAllocationRequest {
                         module: compiled_module.module().clone(),
+                        unique_id: Some(compiled_module.unique_id()),
                         memfds: self.cur.module.memfds().clone(),
                         image_base: compiled_module.code().as_ptr() as usize,
                         functions: compiled_module.functions(),

crates/wasmtime/src/store.rs

@@ -426,6 +426,7 @@ impl<T> Store<T> {
                     shared_signatures: None.into(),
                     imports: Default::default(),
                     module: Arc::new(wasmtime_environ::Module::default()),
+                    unique_id: None,
                     memfds: None,
                     store: StorePtr::empty(),
                     wasm_data: &[],

crates/wasmtime/src/trampoline.rs

@@ -41,6 +41,7 @@ fn create_handle(
         let handle = OnDemandInstanceAllocator::new(config.mem_creator.clone(), 0).allocate(
             InstanceAllocationRequest {
                 module: Arc::new(module),
+                unique_id: None,
                 memfds: None,
                 functions,
                 image_base: 0,

crates/wasmtime/src/trampoline/func.rs

@@ -161,6 +161,7 @@ pub unsafe fn create_raw_function(
     Ok(
         OnDemandInstanceAllocator::default().allocate(InstanceAllocationRequest {
             module: Arc::new(module),
+            unique_id: None,
             memfds: None,
             functions: &functions,
             image_base: (*func).as_ptr() as usize,