Allocate Graph memory from Ruby GC

ext/rubydex/graph.c

@@ -38,10 +38,14 @@ static const char *extract_self_receiver(VALUE opts) {
     return StringValueCStr(kwarg_val);
 }
 
-// Free function for the custom Graph allocator. We always have to call into Rust to free data allocated by it
+// Free function for the custom Graph allocator.
 static void graph_free(void *ptr) {
     if (ptr) {
-        rdx_graph_free(ptr);
+        // let the Rust side drop the Graph struct internally.
+        rdx_graph_drop(ptr);
+
+        // Free the TypeData Ruby object itself
+        xfree(ptr);
     }
 }
 
@@ -58,11 +62,18 @@ const rb_data_type_t graph_type = {
     .flags = RUBY_TYPED_FREE_IMMEDIATELY,
 };
 
-// Custom allocator for the Graph class. Calls into Rust to create a new `Arc<Mutex<Graph>>` that gets stored internally
-// as a void pointer
+// Custom allocator for the Graph class.
+// Requests enough memory from the Ruby GC to fit a `Graph` Rust struct, then initializes it in-place.
+// Only the `Graph` Rust struct itself is in the Ruby heap. Everything else it points to (e.g. all its hash maps' storage)
+// are still normal Rust allocations from the Rust allocator, unknown to the Ruby GC.
 static VALUE rdxr_graph_alloc(VALUE klass) {
-    void *graph = rdx_graph_new();
-    return TypedData_Wrap_Struct(klass, &graph_type, graph);
+    void *graph;
+    // Can't use `TypedData_Make_Struct`, because the Graph is a Rust type that isn't exposed directly to C.
+    VALUE graph_obj = rb_data_typed_object_make(klass, &graph_type, &graph, RDX_GRAPH_SIZE);
+
+    rdx_graph_init(graph);
+
+    return graph_obj;
 }
 
 // Graph#index_all: (Array[String] file_paths) -> Array[String]

ext/rubydex/handle.h

@@ -35,14 +35,15 @@ static const rb_data_type_t handle_type = {
 };
 
 static VALUE rdxr_handle_alloc(VALUE klass) {
-    HandleData *data = ALLOC(HandleData);
+    HandleData *data;
+    VALUE handle_obj = TypedData_Make_Struct(klass, HandleData, &handle_type, data);
 
     *data = (HandleData) {
         .graph_obj = Qnil,
         .id = 0,
     };
 
-    return TypedData_Wrap_Struct(klass, &handle_type, data);
+    return handle_obj;
 }
 
 static VALUE rdxr_handle_initialize(VALUE self, VALUE graph_obj, VALUE id_val) {

rust/rubydex-sys/src/declaration_api.rs

@@ -243,7 +243,7 @@ pub unsafe extern "C" fn rdx_declaration_unqualified_name(pointer: GraphPointer,
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - The returned pointer must be freed with `rdx_declaration_definitions_iter_free`.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn rdx_declaration_definitions_iter_new(
@@ -452,7 +452,7 @@ pub unsafe extern "C" fn rdx_constant_alias_target(pointer: GraphPointer, decl_i
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - The returned pointer must be freed with `rdx_constant_references_iter_free`.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn rdx_declaration_constant_references_iter_new(
@@ -485,7 +485,7 @@ pub unsafe extern "C" fn rdx_declaration_constant_references_iter_new(
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - The returned pointer must be freed with `rdx_method_references_iter_free`.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn rdx_declaration_method_references_iter_new(

rust/rubydex-sys/src/definition_api.rs

@@ -159,7 +159,7 @@ pub struct CommentArray {
 /// Caller must free the returned pointer with `rdx_definition_comments_free` and each inner string with `free_c_string` if needed.
 ///
 /// # Safety
-/// - `pointer` must be a valid pointer previously returned by `rdx_graph_new`.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `definition_id` must be a valid definition id.
 ///
 /// # Panics
@@ -232,7 +232,7 @@ pub unsafe extern "C" fn rdx_definition_comments_free(ptr: *mut CommentArray) {
 /// Caller must free the returned pointer with `rdx_location_free`.
 ///
 /// # Safety
-/// - `pointer` must be a valid pointer previously returned by `rdx_graph_new`.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `definition_id` must be a valid definition id.
 ///
 /// # Panics
@@ -256,7 +256,7 @@ pub unsafe extern "C" fn rdx_definition_location(pointer: GraphPointer, definiti
 /// with `free_c_declaration`.
 ///
 /// # Safety
-/// - `pointer` must be a valid pointer previously returned by `rdx_graph_new`.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `definition_id` must be a valid definition id.
 ///
 /// # Panics
@@ -280,7 +280,7 @@ pub unsafe extern "C" fn rdx_definition_declaration(pointer: GraphPointer, defin
 /// Caller must free the returned pointer with `free_u64`.
 ///
 /// # Safety
-/// - `pointer` must be a valid pointer previously returned by `rdx_graph_new`.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `definition_id` must be a valid definition id.
 ///
 /// # Panics
@@ -331,7 +331,7 @@ where
 /// Returns true if the definition is deprecated.
 ///
 /// # Safety
-/// - `pointer` must be a valid pointer previously returned by `rdx_graph_new`.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `definition_id` must be a valid definition id.
 ///
 /// # Panics
@@ -352,7 +352,7 @@ pub unsafe extern "C" fn rdx_definition_is_deprecated(pointer: GraphPointer, def
 /// Caller must free the returned pointer with `rdx_location_free`.
 ///
 /// # Safety
-/// - `pointer` must be a valid pointer previously returned by `rdx_graph_new`.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `definition_id` must be a valid definition id.
 ///
 /// # Panics
@@ -376,7 +376,7 @@ pub unsafe extern "C" fn rdx_definition_name_location(pointer: GraphPointer, def
 /// must free with `free_c_constant_reference`.
 ///
 /// # Safety
-/// - `pointer` must be a valid pointer previously returned by `rdx_graph_new`.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `definition_id` must be a valid definition id for a class definition.
 ///
 /// # Panics
@@ -462,7 +462,7 @@ fn map_mixin_kind(mixin: &Mixin) -> MixinKind {
 /// Returns NULL for definition types that do not support mixins.
 ///
 /// # Safety
-/// - `pointer` must be a valid pointer previously returned by `rdx_graph_new`.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `definition_id` must be a valid definition id.
 ///
 /// # Panics

rust/rubydex-sys/src/diagnostic_api.rs

@@ -33,7 +33,7 @@ impl DiagnosticArray {
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - The pointed graph must remain alive for the duration of the call.
 ///
 /// # Panics

rust/rubydex-sys/src/document_api.rs

@@ -69,7 +69,7 @@ pub unsafe extern "C" fn rdx_document_uri(pointer: GraphPointer, uri_id: u64) ->
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - The returned pointer must be freed with `rdx_document_definitions_iter_free`.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn rdx_document_definitions_iter_new(pointer: GraphPointer, uri_id: u64) -> *mut DefinitionsIter {

rust/rubydex-sys/src/graph_api.rs

@@ -23,38 +23,55 @@ use std::{mem, ptr};
 
 pub type GraphPointer = *mut c_void;
 
-/// Creates a new graph within a mutex. This is meant to be used when creating new Graph objects in Ruby
+/// Returns the number of bytes needed to store a Graph in externally allocated memory.
 #[unsafe(no_mangle)]
-pub extern "C" fn rdx_graph_new() -> GraphPointer {
-    Box::into_raw(Box::new(Graph::new())) as GraphPointer
+pub static RDX_GRAPH_SIZE: usize = mem::size_of::<Graph>();
+
+/// Initializes a Graph in-place at the given `pointer`.
+///
+/// # Safety
+///
+/// `pointer` must point to valid, properly aligned memory of at least `RDX_GRAPH_SIZE` bytes.
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn rdx_graph_init(pointer: GraphPointer) {
+    // Ruby's allocator only guarantees 16 byte alignment on the 64-bit platforms we support.
+    // Let's make sure we don't have higher alignment requirements (e.g. if we add a u128 in the future).
+    const _: () = assert!(
+        mem::align_of::<Graph>() <= 16,
+        "Graph alignment exceeds the 16-byte alignment guaranteed by Ruby's allocator"
+    );
+
+    unsafe {
+        pointer.cast::<Graph>().write(Graph::new());
+    }
 }
 
-/// Frees a Graph through its pointer
+/// Drops a Graph initialized by `rdx_graph_init` without freeing the underlying memory.
+///
+/// # Safety
+///
+/// `pointer` must point to a valid initialized Graph.
 #[unsafe(no_mangle)]
-pub extern "C" fn rdx_graph_free(pointer: GraphPointer) {
+pub unsafe extern "C" fn rdx_graph_drop(pointer: GraphPointer) {
     unsafe {
-        let _ = Box::from_raw(pointer.cast::<Graph>());
+        ptr::drop_in_place(pointer.cast::<Graph>());
     }
 }
 
 pub fn with_graph<F, T>(pointer: GraphPointer, action: F) -> T
 where
     F: FnOnce(&Graph) -> T,
 {
-    let mut graph = unsafe { Box::from_raw(pointer.cast::<Graph>()) };
-    let result = action(&mut graph);
-    mem::forget(graph);
-    result
+    let graph = unsafe { &*pointer.cast::<Graph>() };
+    action(graph)
 }
 
 fn with_mut_graph<F, T>(pointer: GraphPointer, action: F) -> T
 where
     F: FnOnce(&mut Graph) -> T,
 {
-    let mut graph = unsafe { Box::from_raw(pointer.cast::<Graph>()) };
-    let result = action(&mut graph);
-    mem::forget(graph);
-    result
+    let graph = unsafe { &mut *pointer.cast::<Graph>() };
+    action(graph)
 }
 
 /// Searches the graph using exact substring matching
@@ -165,7 +182,7 @@ pub unsafe extern "C" fn rdx_graph_resolve_constant(
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `paths` must be an array of `count` valid, null-terminated UTF-8 strings.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn rdx_graph_exclude_paths(pointer: GraphPointer, paths: *const *const c_char, count: usize) {
@@ -179,7 +196,7 @@ pub unsafe extern "C" fn rdx_graph_exclude_paths(pointer: GraphPointer, paths: *
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `out_count` must be a valid, writable pointer.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn rdx_graph_excluded_paths(
@@ -318,7 +335,7 @@ pub extern "C" fn rdx_graph_resolve(pointer: GraphPointer) {
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `out_error_count` must be a valid, writable pointer.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn rdx_check_integrity(
@@ -378,7 +395,7 @@ pub unsafe extern "C" fn rdx_graph_set_encoding(pointer: GraphPointer, encoding_
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - The returned pointer must be freed with `rdx_graph_declarations_iter_free`.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn rdx_graph_declarations_iter_new(pointer: GraphPointer) -> *mut DeclarationsIter {
@@ -399,7 +416,7 @@ pub unsafe extern "C" fn rdx_graph_declarations_iter_new(pointer: GraphPointer)
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - The returned pointer must be freed with `rdx_graph_documents_iter_free`.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn rdx_graph_documents_iter_new(pointer: GraphPointer) -> *mut DocumentsIter {
@@ -441,7 +458,7 @@ pub unsafe extern "C" fn rdx_graph_get_declaration(pointer: GraphPointer, name:
 /// Creates a new iterator over constant references by snapshotting the current set of IDs.
 ///
 /// # Safety
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn rdx_graph_constant_references_iter_new(pointer: GraphPointer) -> *mut ConstantReferencesIter {
     with_graph(pointer, |graph| {
@@ -472,7 +489,7 @@ pub unsafe extern "C" fn rdx_graph_constant_references_iter_new(pointer: GraphPo
 /// Creates a new iterator over method references by snapshotting the current set of IDs.
 ///
 /// # Safety
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn rdx_graph_method_references_iter_new(pointer: GraphPointer) -> *mut MethodReferencesIter {
     with_graph(pointer, |graph| {
@@ -491,7 +508,7 @@ pub unsafe extern "C" fn rdx_graph_method_references_iter_new(pointer: GraphPoin
 /// Caller must free with the returned pointer.
 ///
 /// # Safety
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `require_path` must be a valid, null-terminated UTF-8 string.
 /// - `load_paths` must be an array of `load_paths_count` valid, null-terminated UTF-8 strings.
 #[unsafe(no_mangle)]
@@ -521,7 +538,7 @@ pub unsafe extern "C" fn rdx_resolve_require_path(
 /// Caller must free with `free_c_string_array`.
 ///
 /// # Safety
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `load_path` must be an array of `load_path_count` valid, null-terminated UTF-8 strings.
 /// - `out_count` must be a valid, writable pointer.
 #[unsafe(no_mangle)]
@@ -568,7 +585,7 @@ pub enum IndexSourceResult {
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `uri` must be a valid, null-terminated UTF-8 string.
 /// - `language_id` must be either null or a valid, null-terminated UTF-8 string.
 /// - `source` must point to a valid UTF-8 byte buffer of at least `source_len` bytes.
@@ -799,7 +816,7 @@ fn run_and_finalize_completion(
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `nesting` must point to `nesting_count` valid, null-terminated UTF-8 strings.
 /// - `self_receiver` must be null or a valid, null-terminated UTF-8 string. When non-null, it
 ///   overrides the self-type (e.g., `"Foo::<Foo>"` for completion inside `def Foo.bar`), while
@@ -836,7 +853,7 @@ pub unsafe extern "C" fn rdx_graph_complete_expression(
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `name` must be a valid, null-terminated UTF-8 string (FQN of the namespace).
 /// - `self_receiver` must be null or a valid, null-terminated UTF-8 string. When non-null, it
 ///   is the caller's runtime self type (e.g., for filtering `private_class_method` visibility).
@@ -870,7 +887,7 @@ pub unsafe extern "C" fn rdx_graph_complete_namespace_access(
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `name` must be a valid, null-terminated UTF-8 string (FQN of the receiver).
 /// - `self_receiver` must be null or a valid, null-terminated UTF-8 string. When non-null, it
 ///   is the caller's runtime self type, used for MRI-style visibility checks.
@@ -904,7 +921,7 @@ pub unsafe extern "C" fn rdx_graph_complete_method_call(
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `name` must be a valid, null-terminated UTF-8 string (FQN of the method).
 /// - `nesting` must point to `nesting_count` valid, null-terminated UTF-8 strings.
 /// - `self_receiver` must be null or a valid, null-terminated UTF-8 string. See
@@ -1001,7 +1018,7 @@ pub enum CVisibility {
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid `GraphPointer` previously returned by this crate.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn rdx_graph_visibility(pointer: GraphPointer, declaration_id: u64) -> *const CVisibility {
     with_graph(pointer, |graph| {

rust/rubydex-sys/src/reference_api.rs

@@ -175,7 +175,7 @@ pub unsafe extern "C" fn rdx_method_reference_name(pointer: GraphPointer, refere
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid pointer previously returned by `rdx_graph_new`.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `reference_id` must be a valid reference id.
 ///
 /// # Panics
@@ -268,7 +268,7 @@ pub unsafe extern "C" fn rdx_method_reference_receiver_declaration(
 ///
 /// # Safety
 ///
-/// - `pointer` must be a valid pointer previously returned by `rdx_graph_new`.
+/// - `pointer` must be a valid pointer previously initialized by `rdx_graph_init`.
 /// - `reference_id` must be a valid reference id.
 ///
 /// # Panics