feat(introspection): implement experimental introspection feature with multiple App instances

actix-web/examples/introspection.rs

@@ -32,20 +32,20 @@ async fn main() -> std::io::Result<()> {
         }
 
         // GET /introspection for JSON response
-        async fn introspection_handler_json() -> impl Responder {
+        async fn introspection_handler_json(
-            use actix_web::introspection::introspection_report_as_json;
+            tree: web::Data<actix_web::introspection::IntrospectionTree>,
-
+        ) -> impl Responder {
-            let report = introspection_report_as_json();
+            let report = tree.report_as_json();
             HttpResponse::Ok()
                 .content_type("application/json")
                 .body(report)
         }
 
         // GET /introspection for plain text response
-        async fn introspection_handler_text() -> impl Responder {
+        async fn introspection_handler_text(
-            use actix_web::introspection::introspection_report_as_text;
+            tree: web::Data<actix_web::introspection::IntrospectionTree>,
-
+        ) -> impl Responder {
-            let report = introspection_report_as_text();
+            let report = tree.report_as_text();
             HttpResponse::Ok().content_type("text/plain").body(report)
         }
 
@@ -242,7 +242,7 @@ async fn main() -> std::io::Result<()> {
                         .to(HttpResponse::MethodNotAllowed),
                 )
         })
-        .workers(1)
+        .workers(5)
         .bind("127.0.0.1:8080")?;
 
         server.run().await

actix-web/examples/introspection_multi_servers.rs

@@ -0,0 +1,52 @@
+// Example showcasing the experimental introspection feature with multiple App instances.
+// Run with: `cargo run --features experimental-introspection --example introspection_multi_servers`
+
+#[actix_web::main]
+async fn main() -> std::io::Result<()> {
+    #[cfg(feature = "experimental-introspection")]
+    {
+        use actix_web::{web, App, HttpResponse, HttpServer, Responder};
+        use futures_util::future;
+
+        async fn introspection_handler(
+            tree: web::Data<actix_web::introspection::IntrospectionTree>,
+        ) -> impl Responder {
+            HttpResponse::Ok()
+                .content_type("text/plain")
+                .body(tree.report_as_text())
+        }
+
+        async fn index() -> impl Responder {
+            HttpResponse::Ok().body("Hello from app")
+        }
+
+        let srv1 = HttpServer::new(|| {
+            App::new()
+                .service(web::resource("/a").route(web::get().to(index)))
+                .service(
+                    web::resource("/introspection").route(web::get().to(introspection_handler)),
+                )
+        })
+        .workers(8)
+        .bind("127.0.0.1:8081")?
+        .run();
+
+        let srv2 = HttpServer::new(|| {
+            App::new()
+                .service(web::resource("/b").route(web::get().to(index)))
+                .service(
+                    web::resource("/introspection").route(web::get().to(introspection_handler)),
+                )
+        })
+        .workers(3)
+        .bind("127.0.0.1:8082")?
+        .run();
+
+        future::try_join(srv1, srv2).await?;
+    }
+    #[cfg(not(feature = "experimental-introspection"))]
+    {
+        eprintln!("This example requires the 'experimental-introspection' feature to be enabled.");
+    }
+    Ok(())
+}

actix-web/src/app.rs

@@ -30,6 +30,8 @@ pub struct App<T> {
     data_factories: Vec<FnDataFactory>,
     external: Vec<ResourceDef>,
     extensions: Extensions,
+    #[cfg(feature = "experimental-introspection")]
+    introspector: Rc<RefCell<crate::introspection::IntrospectionCollector>>,
 }
 
 impl App<AppEntry> {
@@ -46,6 +48,10 @@ impl App<AppEntry> {
             factory_ref,
             external: Vec::new(),
             extensions: Extensions::new(),
+            #[cfg(feature = "experimental-introspection")]
+            introspector: Rc::new(RefCell::new(
+                crate::introspection::IntrospectionCollector::new(),
+            )),
         }
     }
 }
@@ -366,6 +372,8 @@ where
             factory_ref: self.factory_ref,
             external: self.external,
             extensions: self.extensions,
+            #[cfg(feature = "experimental-introspection")]
+            introspector: self.introspector,
         }
     }
 
@@ -429,6 +437,8 @@ where
             factory_ref: self.factory_ref,
             external: self.external,
             extensions: self.extensions,
+            #[cfg(feature = "experimental-introspection")]
+            introspector: self.introspector,
         }
     }
 }
@@ -453,6 +463,8 @@ where
             default: self.default,
             factory_ref: self.factory_ref,
             extensions: RefCell::new(Some(self.extensions)),
+            #[cfg(feature = "experimental-introspection")]
+            introspector: Rc::clone(&self.introspector),
         }
     }
 }

actix-web/src/app_service.rs

@@ -41,6 +41,8 @@ where
     pub(crate) default: Option<Rc<BoxedHttpServiceFactory>>,
     pub(crate) factory_ref: Rc<RefCell<Option<AppRoutingFactory>>>,
     pub(crate) external: RefCell<Vec<ResourceDef>>,
+    #[cfg(feature = "experimental-introspection")]
+    pub(crate) introspector: Rc<RefCell<crate::introspection::IntrospectionCollector>>,
 }
 
 impl<T, B> ServiceFactory<Request> for AppInit<T, B>
@@ -72,6 +74,10 @@ where
 
         // create App config to pass to child services
         let mut config = AppService::new(config, Rc::clone(&default));
+        #[cfg(feature = "experimental-introspection")]
+        {
+            config.introspector = Rc::clone(&self.introspector);
+        }
 
         // register services
         mem::take(&mut *self.services.borrow_mut())
@@ -80,6 +86,9 @@ where
 
         let mut rmap = ResourceMap::new(ResourceDef::prefix(""));
 
+        #[cfg(feature = "experimental-introspection")]
+        let (config, services, _) = config.into_services();
+        #[cfg(not(feature = "experimental-introspection"))]
         let (config, services) = config.into_services();
 
         // complete pipeline creation.
@@ -110,6 +119,8 @@ where
 
         // construct app service and middleware service factory future.
         let endpoint_fut = self.endpoint.new_service(());
+        #[cfg(feature = "experimental-introspection")]
+        let introspector = Rc::clone(&self.introspector);
 
         // take extensions or create new one as app data container.
         let mut app_data = self.extensions.borrow_mut().take().unwrap_or_default();
@@ -132,7 +143,8 @@ where
 
             #[cfg(feature = "experimental-introspection")]
             {
-                crate::introspection::finalize_registry();
+                let tree = introspector.borrow_mut().finalize();
+                app_data.insert(crate::web::Data::new(tree));
             }
 
             Ok(AppInitService {

actix-web/src/config.rs

@@ -32,6 +32,9 @@ pub struct AppService {
     )>,
     #[cfg(feature = "experimental-introspection")]
     pub current_prefix: String,
+    #[cfg(feature = "experimental-introspection")]
+    pub(crate) introspector:
+        std::rc::Rc<std::cell::RefCell<crate::introspection::IntrospectionCollector>>,
 }
 
 impl AppService {
@@ -44,6 +47,10 @@ impl AppService {
             services: Vec::new(),
             #[cfg(feature = "experimental-introspection")]
             current_prefix: "".to_string(),
+            #[cfg(feature = "experimental-introspection")]
+            introspector: std::rc::Rc::new(std::cell::RefCell::new(
+                crate::introspection::IntrospectionCollector::new(),
+            )),
         }
     }
 
@@ -53,6 +60,24 @@ impl AppService {
     }
 
     #[allow(clippy::type_complexity)]
+    #[cfg(feature = "experimental-introspection")]
+    pub(crate) fn into_services(
+        self,
+    ) -> (
+        AppConfig,
+        Vec<(
+            ResourceDef,
+            BoxedHttpServiceFactory,
+            Option<Guards>,
+            Option<Rc<ResourceMap>>,
+        )>,
+        std::rc::Rc<std::cell::RefCell<crate::introspection::IntrospectionCollector>>,
+    ) {
+        (self.config, self.services, self.introspector)
+    }
+
+    #[allow(clippy::type_complexity)]
+    #[cfg(not(feature = "experimental-introspection"))]
     pub(crate) fn into_services(
         self,
     ) -> (
@@ -77,6 +102,8 @@ impl AppService {
             root: false,
             #[cfg(feature = "experimental-introspection")]
             current_prefix: self.current_prefix.clone(),
+            #[cfg(feature = "experimental-introspection")]
+            introspector: std::rc::Rc::clone(&self.introspector),
         }
     }
 
@@ -111,8 +138,6 @@ impl AppService {
         {
             use std::borrow::Borrow;
 
-            use crate::introspection;
-
             // Build the full path for introspection
             let pat = rdef.pattern().unwrap_or("").to_string();
 
@@ -148,7 +173,12 @@ impl AppService {
 
             // Determine if the registered service is a resource
             let is_resource = rdef.pattern().is_some();
-            introspection::register_pattern_detail(full_path, methods, guard_names, is_resource);
+            self.introspector.borrow_mut().register_pattern_detail(
+                full_path,
+                methods,
+                guard_names,
+                is_resource,
+            );
         }
 
         self.services

actix-web/src/introspection.rs

@@ -1,61 +1,14 @@
-use std::{
+use std::{collections::HashMap, fmt::Write as FmtWrite};
-    collections::HashMap,
-    fmt::Write as FmtWrite,
-    sync::{
-        atomic::{AtomicBool, Ordering},
-        Mutex, OnceLock,
-    },
-    thread,
-};
 
 use serde::Serialize;
 
 use crate::http::Method;
 
-static REGISTRY: OnceLock<Mutex<IntrospectionNode>> = OnceLock::new();
-static DETAIL_REGISTRY: OnceLock<Mutex<HashMap<String, RouteDetail>>> = OnceLock::new();
-static DESIGNATED_THREAD: OnceLock<thread::ThreadId> = OnceLock::new();
-static IS_INITIALIZED: AtomicBool = AtomicBool::new(false);
-
-fn initialize_registry() {
-    REGISTRY.get_or_init(|| {
-        Mutex::new(IntrospectionNode::new(
-            ResourceType::App,
-            "".into(),
-            "".into(),
-        ))
-    });
-}
-
-fn get_registry() -> &'static Mutex<IntrospectionNode> {
-    REGISTRY.get().expect("Registry not initialized")
-}
-
-fn initialize_detail_registry() {
-    DETAIL_REGISTRY.get_or_init(|| Mutex::new(HashMap::new()));
-}
-
-fn get_detail_registry() -> &'static Mutex<HashMap<String, RouteDetail>> {
-    DETAIL_REGISTRY
-        .get()
-        .expect("Detail registry not initialized")
-}
-
-fn is_designated_thread() -> bool {
-    let current_id = thread::current().id();
-    DESIGNATED_THREAD.get_or_init(|| {
-        IS_INITIALIZED.store(true, Ordering::SeqCst);
-        current_id // Assign the first thread that calls this function
-    });
-
-    *DESIGNATED_THREAD.get().unwrap() == current_id
-}
-
 #[derive(Clone)]
 pub struct RouteDetail {
     methods: Vec<Method>,
     guards: Vec<String>,
-    is_resource: bool, // Indicates if this detail is for a final resource endpoint
+    is_resource: bool,
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -74,6 +27,7 @@ pub struct IntrospectionNode {
     pub guards: Vec<String>,
     pub children: Vec<IntrospectionNode>,
 }
+
 #[derive(Debug, Clone, Serialize)]
 pub struct IntrospectionReportItem {
     pub full_path: String,
@@ -112,16 +66,10 @@ impl From<&IntrospectionNode> for Vec<IntrospectionReportItem> {
             };
 
             if !node.methods.is_empty() || !node.guards.is_empty() {
-                // Filter guards that are already represented in methods
                 let filtered_guards: Vec<String> = node
                     .guards
                     .iter()
-                    .filter(|guard| {
+                    .filter(|guard| !node.methods.iter().any(|m| m.to_string() == **guard))
-                        !node
-                            .methods
-                            .iter()
-                            .any(|method| method.to_string() == **guard)
-                    })
                     .cloned()
                     .collect();
 
@@ -143,35 +91,59 @@ impl From<&IntrospectionNode> for Vec<IntrospectionReportItem> {
     }
 }
 
-pub(crate) fn finalize_registry() {
+#[derive(Clone, Default)]
-    if !is_designated_thread() {
+pub struct IntrospectionCollector {
-        return;
+    details: HashMap<String, RouteDetail>,
 }
 
-    initialize_registry();
+impl IntrospectionCollector {
-    initialize_detail_registry();
+    pub fn new() -> Self {
+        Self {
+            details: HashMap::new(),
+        }
+    }
 
-    let detail_registry = get_detail_registry().lock().unwrap();
+    pub fn register_pattern_detail(
+        &mut self,
+        full_path: String,
+        methods: Vec<Method>,
+        guards: Vec<String>,
+        is_resource: bool,
+    ) {
+        self.details
+            .entry(full_path)
+            .and_modify(|d| {
+                update_unique(&mut d.methods, &methods);
+                update_unique(&mut d.guards, &guards);
+                if !d.is_resource && is_resource {
+                    d.is_resource = true;
+                }
+            })
+            .or_insert(RouteDetail {
+                methods,
+                guards,
+                is_resource,
+            });
+    }
+
+    pub fn finalize(&mut self) -> IntrospectionTree {
+        let detail_registry = std::mem::take(&mut self.details);
         let mut root = IntrospectionNode::new(ResourceType::App, "".into(), "".into());
 
-    // Build the introspection tree directly from the detail registry
+        for (full_path, _) in detail_registry.iter() {
-    for (full_path, _detail) in detail_registry.iter() {
             let parts: Vec<&str> = full_path.split('/').collect();
             let mut current_node = &mut root;
 
             for (i, part) in parts.iter().enumerate() {
-            // Find the index of the existing child
                 let existing_child_index = current_node
                     .children
                     .iter()
                     .position(|n| n.pattern == *part);
 
-            let child_index = if let Some(child_index) = existing_child_index {
+                let child_index = if let Some(idx) = existing_child_index {
-                child_index
+                    idx
                 } else {
-                // If it doesn't exist, create a new node and get its index
                     let child_full_path = parts[..=i].join("/");
-                // Determine the kind based on whether this path exists as a resource in the detail registry
                     let kind = if detail_registry
                         .get(&child_full_path)
                         .is_some_and(|d| d.is_resource)
@@ -185,10 +157,8 @@ pub(crate) fn finalize_registry() {
                     current_node.children.len() - 1
                 };
 
-            // Get a mutable reference to the child node
                 current_node = &mut current_node.children[child_index];
 
-            // If this node is marked as a resource, update its methods and guards
                 if let ResourceType::Resource = current_node.kind {
                     if let Some(detail) = detail_registry.get(&current_node.full_path) {
                         update_unique(&mut current_node.methods, &detail.methods);
@@ -198,48 +168,18 @@ pub(crate) fn finalize_registry() {
             }
         }
 
-    *get_registry().lock().unwrap() = root;
+        IntrospectionTree { root }
-}
-
-fn update_unique<T: Clone + PartialEq>(existing: &mut Vec<T>, new_items: &[T]) {
-    for item in new_items {
-        if !existing.contains(item) {
-            existing.push(item.clone());
-        }
     }
 }
 
-pub(crate) fn register_pattern_detail(
+#[derive(Clone)]
-    full_path: String,
+pub struct IntrospectionTree {
-    methods: Vec<Method>,
+    pub root: IntrospectionNode,
-    guards: Vec<String>,
-    is_resource: bool,
-) {
-    if !is_designated_thread() {
-        return;
-    }
-    initialize_detail_registry();
-    let mut reg = get_detail_registry().lock().unwrap();
-    reg.entry(full_path)
-        .and_modify(|d| {
-            update_unique(&mut d.methods, &methods);
-            update_unique(&mut d.guards, &guards);
-            // If the existing entry was not a resource but the new one is, update the kind
-            if !d.is_resource && is_resource {
-                d.is_resource = true;
-            }
-        })
-        .or_insert(RouteDetail {
-            methods,
-            guards,
-            is_resource,
-        });
 }
 
-pub fn introspection_report_as_text() -> String {
+impl IntrospectionTree {
-    let registry = get_registry();
+    pub fn report_as_text(&self) -> String {
-    let node = registry.lock().unwrap();
+        let report_items: Vec<IntrospectionReportItem> = (&self.root).into();
-    let report_items: Vec<IntrospectionReportItem> = (&*node).into();
 
         let mut buf = String::new();
         for item in report_items {
@@ -254,10 +194,16 @@ pub fn introspection_report_as_text() -> String {
         buf
     }
 
-pub fn introspection_report_as_json() -> String {
+    pub fn report_as_json(&self) -> String {
-    let registry = get_registry();
+        let report_items: Vec<IntrospectionReportItem> = (&self.root).into();
-    let node = registry.lock().unwrap();
-    let report_items: Vec<IntrospectionReportItem> = (&*node).into();
-
         serde_json::to_string_pretty(&report_items).unwrap()
     }
+}
+
+fn update_unique<T: Clone + PartialEq>(existing: &mut Vec<T>, new_items: &[T]) {
+    for item in new_items {
+        if !existing.contains(item) {
+            existing.push(item.clone());
+        }
+    }
+}

actix-web/src/resource.rs

@@ -432,7 +432,7 @@ where
         };
         #[cfg(feature = "experimental-introspection")]
         {
-            use crate::{http::Method, introspection};
+            use crate::http::Method;
 
             let guards_routes = routes.iter().map(|r| r.guards()).collect::<Vec<_>>();
 
@@ -464,7 +464,7 @@ where
                     })
                     .collect::<Vec<_>>();
 
-                introspection::register_pattern_detail(
+                config.introspector.borrow_mut().register_pattern_detail(
                     full_path.clone(),
                     methods,
                     guard_names,