Serve shared rustdoc resources via special handler

This removes the need for things like
onur/rust@482575f
and allows launching a local docs.rs instance without having to build a
patched compiler.

Author: jonas-schievink

src/web/mod.rs

@@ -69,6 +69,7 @@ const OPENSEARCH_XML: &'static [u8] = include_bytes!("opensearch.xml");
 
 
 struct CratesfyiHandler {
+    shared_resource_handler: Box<Handler>,
     router_handler: Box<Handler>,
     database_file_handler: Box<Handler>,
     static_handler: Box<Handler>,
@@ -186,12 +187,14 @@ impl CratesfyiHandler {
                    rustdoc::rustdoc_html_server_handler,
                    "crate_version_target_html");
 
+        let shared_resources = Self::chain(rustdoc::SharedResourceHandler);
         let router_chain = Self::chain(router);
         let prefix = PathBuf::from(env::var("CRATESFYI_PREFIX").unwrap()).join("public_html");
         let static_handler = Static::new(prefix)
             .cache(Duration::from_secs(STATIC_FILE_CACHE_DURATION));
 
         CratesfyiHandler {
+            shared_resource_handler: Box::new(shared_resources),
             router_handler: Box::new(router_chain),
             database_file_handler: Box::new(file::DatabaseFileHandler),
             static_handler: Box::new(static_handler),
@@ -202,10 +205,13 @@ impl CratesfyiHandler {
 
 impl Handler for CratesfyiHandler {
     fn handle(&self, req: &mut Request) -> IronResult<Response> {
-        // try router first then db/static file handler
+        // try serving shared rustdoc resources first, then router, then db/static file handler
         // return 404 if none of them return Ok
-        self.router_handler
+        self.shared_resource_handler
             .handle(req)
+            .or_else(|e| {
+                self.router_handler.handle(req).or(Err(e))
+            })
             .or_else(|e| {
                 // if router fails try to serve files from database first
                 self.database_file_handler.handle(req).or(Err(e))

src/web/rustdoc.rs

@@ -16,7 +16,7 @@ use rustc_serialize::json::{Json, ToJson};
 use std::collections::BTreeMap;
 use iron::headers::{Expires, HttpDate, CacheControl, CacheDirective};
 use time;
-
+use iron::Handler;
 
 
 #[derive(Debug)]
@@ -110,6 +110,10 @@ pub fn rustdoc_redirector_handler(req: &mut Request) -> IronResult<Response> {
 }
 
 
+/// Serves documentation generated by rustdoc.
+///
+/// This includes all HTML files for an individual crate, as well as the `search-index.js`, which is
+/// also crate-specific.
 pub fn rustdoc_html_server_handler(req: &mut Request) -> IronResult<Response> {
 
     let router = extension!(req, Router);
@@ -251,3 +255,28 @@ pub fn badge_handler(req: &mut Request) -> IronResult<Response> {
                                        CacheDirective::MustRevalidate]));
     Ok(resp)
 }
+
+/// Serves shared web resources used by rustdoc-generated documentation.
+///
+/// This includes common `css` and `js` files that only change when the compiler is updated, but are
+/// otherwise the same for all crates documented with that compiler. Those have a custom handler to
+/// deduplicate them and save space.
+pub struct SharedResourceHandler;
+
+impl Handler for SharedResourceHandler {
+    fn handle(&self, req: &mut Request) -> IronResult<Response> {
+        let path = req.url.path();
+        let filename = path.last().unwrap();  // unwrap is fine: vector is non-empty
+        let suffix = filename.split('.').last().unwrap();  // unwrap is fine: split always works
+        if ["js", "css", "woff", "svg"].contains(&suffix) {
+            let conn = extension!(req, Pool);
+
+            if let Some(file) = File::from_path(conn, filename) {
+                return Ok(file.serve());
+            }
+        }
+
+        // Just always return a 404 here - the main handler will then try the other handlers
+        Err(IronError::new(Nope::ResourceNotFound, status::NotFound))
+    }
+}