Don't share id_map and deref_id_map

src/librustdoc/html/render/mod.rs

@@ -44,7 +44,6 @@ use std::rc::Rc;
 use std::str;
 use std::string::ToString;
 use std::sync::mpsc::{channel, Receiver};
-use std::sync::Arc;
 
 use itertools::Itertools;
 use rustc_ast_pretty::pprust;
@@ -103,27 +102,42 @@ crate fn ensure_trailing_slash(v: &str) -> impl fmt::Display + '_ {
 crate struct Context<'tcx> {
     /// Current hierarchy of components leading down to what's currently being
     /// rendered
-    crate current: Vec<String>,
+    current: Vec<String>,
     /// The current destination folder of where HTML artifacts should be placed.
     /// This changes as the context descends into the module hierarchy.
-    crate dst: PathBuf,
+    dst: PathBuf,
     /// A flag, which when `true`, will render pages which redirect to the
     /// real location of an item. This is used to allow external links to
     /// publicly reused items to redirect to the right location.
-    crate render_redirect_pages: bool,
+    render_redirect_pages: bool,
     /// The map used to ensure all generated 'id=' attributes are unique.
-    id_map: Rc<RefCell<IdMap>>,
+    id_map: RefCell<IdMap>,
     /// Tracks section IDs for `Deref` targets so they match in both the main
     /// body and the sidebar.
-    deref_id_map: Rc<RefCell<FxHashMap<DefId, String>>>,
-    crate shared: Arc<SharedContext<'tcx>>,
-    all: Rc<RefCell<AllTypes>>,
-    /// Storage for the errors produced while generating documentation so they
-    /// can be printed together at the end.
-    crate errors: Rc<Receiver<String>>,
-    crate cache: Rc<Cache>,
+    deref_id_map: RefCell<FxHashMap<DefId, String>>,
+    /// Shared mutable state.
+    ///
+    /// Issue for improving the situation: [#82381][]
+    ///
+    /// [#82381]: https://github.com/rust-lang/rust/issues/82381
+    shared: Rc<SharedContext<'tcx>>,
+    /// The [`Cache`] used during rendering.
+    ///
+    /// Ideally the cache would be in [`SharedContext`], but it's mutated
+    /// between when the `SharedContext` is created and when `Context`
+    /// is created, so more refactoring would be needed.
+    ///
+    /// It's immutable once in `Context`, so it's not as bad that it's not in
+    /// `SharedContext`.
+    // FIXME: move `cache` to `SharedContext`
+    cache: Rc<Cache>,
 }
 
+// `Context` is cloned a lot, so we don't want the size to grow unexpectedly.
+#[cfg(target_arch = "x86_64")]
+rustc_data_structures::static_assert_size!(Context<'_>, 152);
+
+/// Shared mutable state used in [`Context`] and elsewhere.
 crate struct SharedContext<'tcx> {
     crate tcx: TyCtxt<'tcx>,
     /// The path to the crate root source minus the file name.
@@ -139,16 +153,16 @@ crate struct SharedContext<'tcx> {
     /// The local file sources we've emitted and their respective url-paths.
     crate local_sources: FxHashMap<PathBuf, String>,
     /// Whether the collapsed pass ran
-    crate collapsed: bool,
+    collapsed: bool,
     /// The base-URL of the issue tracker for when an item has been tagged with
     /// an issue number.
-    crate issue_tracker_base_url: Option<String>,
+    issue_tracker_base_url: Option<String>,
     /// The directories that have already been created in this doc run. Used to reduce the number
     /// of spurious `create_dir_all` calls.
-    crate created_dirs: RefCell<FxHashSet<PathBuf>>,
+    created_dirs: RefCell<FxHashSet<PathBuf>>,
     /// This flag indicates whether listings of modules (in the side bar and documentation itself)
     /// should be ordered alphabetically or in order of appearance (in the source code).
-    crate sort_modules_alphabetically: bool,
+    sort_modules_alphabetically: bool,
     /// Additional CSS files to be added to the generated docs.
     crate style_files: Vec<StylePath>,
     /// Suffix to be added on resource files (if suffix is "-v2" then "light.css" becomes
@@ -161,8 +175,12 @@ crate struct SharedContext<'tcx> {
     crate fs: DocFS,
     /// The default edition used to parse doctests.
     crate edition: Edition,
-    crate codes: ErrorCodes,
+    codes: ErrorCodes,
     playground: Option<markdown::Playground>,
+    all: RefCell<AllTypes>,
+    /// Storage for the errors produced while generating documentation so they
+    /// can be printed together at the end.
+    errors: Receiver<String>,
 }
 
 impl<'tcx> Context<'tcx> {
@@ -478,6 +496,8 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             edition,
             codes: ErrorCodes::from(unstable_features.is_nightly_build()),
             playground,
+            all: RefCell::new(AllTypes::new()),
+            errors: receiver,
         };
 
         // Add the default themes to the `Vec` of stylepaths
@@ -504,20 +524,18 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             current: Vec::new(),
             dst,
             render_redirect_pages: false,
-            id_map: Rc::new(RefCell::new(id_map)),
-            deref_id_map: Rc::new(RefCell::new(FxHashMap::default())),
-            shared: Arc::new(scx),
-            all: Rc::new(RefCell::new(AllTypes::new())),
-            errors: Rc::new(receiver),
+            id_map: RefCell::new(id_map),
+            deref_id_map: RefCell::new(FxHashMap::default()),
+            shared: Rc::new(scx),
             cache: Rc::new(cache),
         };
 
         CURRENT_DEPTH.with(|s| s.set(0));
 
         // Write shared runs within a flock; disable thread dispatching of IO temporarily.
-        Arc::get_mut(&mut cx.shared).unwrap().fs.set_sync_only(true);
+        Rc::get_mut(&mut cx.shared).unwrap().fs.set_sync_only(true);
         write_shared(&cx, &krate, index, &md_opts)?;
-        Arc::get_mut(&mut cx.shared).unwrap().fs.set_sync_only(false);
+        Rc::get_mut(&mut cx.shared).unwrap().fs.set_sync_only(false);
         Ok((cx, krate))
     }
 
@@ -558,7 +576,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         } else {
             String::new()
         };
-        let all = self.all.replace(AllTypes::new());
+        let all = self.shared.all.replace(AllTypes::new());
         let v = layout::render(
             &self.shared.layout,
             &page,
@@ -590,8 +608,8 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         self.shared.fs.write(&settings_file, v.as_bytes())?;
 
         // Flush pending errors.
-        Arc::get_mut(&mut self.shared).unwrap().fs.close();
-        let nb_errors = self.errors.iter().map(|err| diag.struct_err(&err).emit()).count();
+        Rc::get_mut(&mut self.shared).unwrap().fs.close();
+        let nb_errors = self.shared.errors.iter().map(|err| diag.struct_err(&err).emit()).count();
         if nb_errors > 0 {
             Err(Error::new(io::Error::new(io::ErrorKind::Other, "I/O error"), ""))
         } else {
@@ -670,7 +688,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             self.shared.fs.write(&joint_dst, buf.as_bytes())?;
 
             if !self.render_redirect_pages {
-                self.all.borrow_mut().append(full_path(self, &item), &item_type);
+                self.shared.all.borrow_mut().append(full_path(self, &item), &item_type);
             }
             // If the item is a macro, redirect from the old macro URL (with !)
             // to the new one (without).
@@ -1572,6 +1590,7 @@ impl Context<'_> {
         };
 
         {
+            // FIXME: remove this once `Context` is no longer cloned
             self.id_map.borrow_mut().reset();
             self.id_map.borrow_mut().populate(&INITIAL_IDS);
         }