share WASI outbound HTTP connection pool across instances (#3240)

Now each `InstanceState` gets a clone of the `AppState` HTTP clients containing
the pools, meaning connections may persist across instances (and thus across
inbound requests).

Signed-off-by: Joel Dice <[email protected]>

Author: dicej

crates/factor-outbound-http/src/lib.rs

@@ -50,11 +50,13 @@ impl Factor for OutboundHttpFactor {
         &self,
         mut ctx: ConfigureAppContext<T, Self>,
     ) -> anyhow::Result<Self::AppState> {
+        let connection_pooling = ctx
+            .take_runtime_config()
+            .unwrap_or_default()
+            .connection_pooling;
         Ok(AppState {
-            connection_pooling: ctx
-                .take_runtime_config()
-                .unwrap_or_default()
-                .connection_pooling,
+            wasi_http_clients: wasi::HttpClients::new(connection_pooling),
+            connection_pooling,
         })
     }
 
@@ -74,7 +76,7 @@ impl Factor for OutboundHttpFactor {
             self_request_origin: None,
             request_interceptor: None,
             spin_http_client: None,
-            wasi_http_clients: None,
+            wasi_http_clients: ctx.app_state().wasi_http_clients.clone(),
             connection_pooling: ctx.app_state().connection_pooling,
         })
     }
@@ -88,9 +90,16 @@ pub struct InstanceState {
     self_request_origin: Option<SelfRequestOrigin>,
     request_interceptor: Option<Arc<dyn OutboundHttpInterceptor>>,
     // Connection-pooling client for 'fermyon:spin/http' interface
+    //
+    // TODO: We could move this to `AppState` to like the
+    // `wasi:http/outgoing-handler` pool for consistency, although it's probably
+    // not a high priority given that `fermyon:spin/http` is deprecated anyway.
     spin_http_client: Option<reqwest::Client>,
-    // Connection pooling client for `wasi:http/outgoing-handler` interface
-    wasi_http_clients: Option<wasi::HttpClients>,
+    // Connection pooling clients for `wasi:http/outgoing-handler` interface
+    //
+    // This is a clone of `AppState::wasi_http_clients`, meaning it is shared
+    // among all instances of the app.
+    wasi_http_clients: wasi::HttpClients,
     connection_pooling: bool,
 }
 
@@ -171,5 +180,7 @@ impl std::fmt::Display for SelfRequestOrigin {
 }
 
 pub struct AppState {
+    // Connection pooling clients for `wasi:http/outgoing-handler` interface
+    wasi_http_clients: wasi::HttpClients,
     connection_pooling: bool,
 }

crates/factor-outbound-http/src/wasi.rs

@@ -101,6 +101,23 @@ pub(super) struct HttpClients {
     https: HttpsClient,
 }
 
+impl HttpClients {
+    pub(super) fn new(enable_pooling: bool) -> Self {
+        let builder = move || {
+            let mut builder = Client::builder(TokioExecutor::new());
+            if !enable_pooling {
+                builder.pool_max_idle_per_host(0);
+            }
+            builder
+        };
+        Self {
+            http1: builder().build(HttpConnector),
+            http2: builder().http2_only(true).build(HttpConnector),
+            https: builder().build(HttpsConnector),
+        }
+    }
+}
+
 pub(crate) struct WasiHttpImplInner<'a> {
     state: &'a mut InstanceState,
     table: &'a mut ResourceTable,
@@ -135,25 +152,6 @@ impl WasiHttpView for WasiHttpImplInner<'_> {
         request: Request<wasmtime_wasi_http::body::HyperOutgoingBody>,
         config: wasmtime_wasi_http::types::OutgoingRequestConfig,
     ) -> wasmtime_wasi_http::HttpResult<wasmtime_wasi_http::types::HostFutureIncomingResponse> {
-        let connection_pooling = self.state.connection_pooling;
-        let builder = move || {
-            let mut builder = Client::builder(TokioExecutor::new());
-            if !connection_pooling {
-                builder.pool_max_idle_per_host(0);
-            }
-            builder
-        };
-
-        let http_clients = self
-            .state
-            .wasi_http_clients
-            .get_or_insert_with(|| HttpClients {
-                http1: builder().build(HttpConnector),
-                http2: builder().http2_only(true).build(HttpConnector),
-                https: builder().build(HttpsConnector),
-            })
-            .clone();
-
         Ok(HostFutureIncomingResponse::Pending(
             wasmtime_wasi::runtime::spawn(
                 send_request_impl(
@@ -164,7 +162,7 @@ impl WasiHttpView for WasiHttpImplInner<'_> {
                     self.state.request_interceptor.clone(),
                     self.state.self_request_origin.clone(),
                     self.state.blocked_networks.clone(),
-                    http_clients,
+                    self.state.wasi_http_clients.clone(),
                 )
                 .in_current_span(),
             ),