add: C APIの#[repr(Rust)]なものへのアクセスをすべて安全にする (VOICEVOX#849)

C APIにおいて、Rust APIのオブジェクトそのものの代わりにトークンのような
1-bit長の構造体ユーザーに渡すようにすることで、次のことを実現する。

1. "delete"時に対象オブジェクトに対するアクセスがあった場合、アクセスが
    終わるまで待つ
2. 次のユーザー操作に対するセーフティネットを張り、パニックするようにす
    る
    1. "delete"後に他の通常のメソッド関数の利用を試みる
    2. "delete"後に"delete"を試みる
    3. そもそもオブジェクトとして変なダングリングポインタが渡される

ドキュメントとしてのsafety requirementsもあわせて緩和する。

Resolves VOICEVOX#836.

Cargo.toml

@@ -58,8 +58,10 @@ ndarray-stats = "0.5.1"
 octocrab = { version = "0.19.0", default-features = false }
 once_cell = "1.20.1"
 ouroboros = "0.18.4"
+parking_lot = "0.12.1"
 parse-display = "0.8.2"
 pollster = "0.3.0"
+predicates = "3.1.2"
 pretty_assertions = "1.4.1"
 proc-macro2 = "1.0.86"
 pyo3 = "0.20.3"

crates/voicevox_core_c_api/Cargo.toml

@@ -25,10 +25,12 @@ chrono = { workspace = true, default-features = false, features = ["clock"] }
 colorchoice.workspace = true
 const_format.workspace = true
 cstr.workspace = true
-derive-getters.workspace = true
+duplicate.workspace = true
 easy-ext.workspace = true
+educe.workspace = true
 itertools.workspace = true
 libc.workspace = true
+parking_lot = { workspace = true, features = ["arc_lock"] }
 process_path.workspace = true
 ref-cast.workspace = true
 serde_json = { workspace = true, features = ["preserve_order"] }
@@ -45,10 +47,12 @@ clap = { workspace = true, features = ["derive"] }
 duct.workspace = true
 easy-ext.workspace = true
 inventory.workspace = true
+indexmap = { workspace = true, features = ["serde"] }
 libloading.workspace = true
 libtest-mimic.workspace = true
 ndarray.workspace = true
 ndarray-stats.workspace = true
+predicates.workspace = true
 regex.workspace = true
 serde = { workspace = true, features = ["derive"] }
 serde_with.workspace = true

crates/voicevox_core_c_api/src/c_impls.rs

@@ -1,11 +1,21 @@
-use std::{ffi::CString, path::Path};
+use std::{
+    collections::HashMap,
+    ffi::CString,
+    path::Path,
+    ptr::NonNull,
+    sync::{Arc, LazyLock},
+};
 
 use camino::Utf8Path;
+use duplicate::duplicate_item;
+use easy_ext::ext;
 use ref_cast::ref_cast_custom;
 use voicevox_core::{InitializeOptions, Result, SpeakerMeta, VoiceModelId};
 
 use crate::{
-    helpers::CApiResult, OpenJtalkRc, VoicevoxOnnxruntime, VoicevoxSynthesizer,
+    helpers::CApiResult,
+    object::{CApiObject, CApiObjectPtrExt as _},
+    OpenJtalkRc, VoicevoxOnnxruntime, VoicevoxSynthesizer, VoicevoxUserDict,
     VoicevoxVoiceModelFile,
 };
 
@@ -61,61 +71,93 @@ macro_rules! to_cstr {
 use to_cstr;
 
 impl OpenJtalkRc {
-    pub(crate) fn new(open_jtalk_dic_dir: impl AsRef<Utf8Path>) -> Result<Self> {
-        Ok(Self {
-            open_jtalk: voicevox_core::blocking::OpenJtalk::new(open_jtalk_dic_dir)?,
-        })
+    pub(crate) fn new(open_jtalk_dic_dir: impl AsRef<Utf8Path>) -> Result<NonNull<Self>> {
+        let body = voicevox_core::blocking::OpenJtalk::new(open_jtalk_dic_dir)?;
+        Ok(<Self as CApiObject>::new(body))
     }
 }
 
 impl VoicevoxSynthesizer {
     pub(crate) fn new(
         onnxruntime: &'static VoicevoxOnnxruntime,
-        open_jtalk: &OpenJtalkRc,
+        open_jtalk: *const OpenJtalkRc,
         options: &InitializeOptions,
-    ) -> Result<Self> {
-        let synthesizer = voicevox_core::blocking::Synthesizer::new(
+    ) -> Result<NonNull<Self>> {
+        let body = voicevox_core::blocking::Synthesizer::new(
             &onnxruntime.0,
-            open_jtalk.open_jtalk.clone(),
+            open_jtalk.body().clone(),
             options,
         )?;
-        Ok(Self { synthesizer })
+        Ok(<Self as CApiObject>::new(body))
     }
+}
 
-    pub(crate) fn onnxruntime(&self) -> &'static VoicevoxOnnxruntime {
-        VoicevoxOnnxruntime::new(self.synthesizer.onnxruntime())
+#[ext(VoicevoxSynthesizerPtrExt)]
+impl *const VoicevoxSynthesizer {
+    pub(crate) fn onnxruntime(self) -> &'static VoicevoxOnnxruntime {
+        VoicevoxOnnxruntime::new(self.body().onnxruntime())
     }
 
     pub(crate) fn load_voice_model(
-        &self,
+        self,
         model: &voicevox_core::blocking::VoiceModelFile,
     ) -> CApiResult<()> {
-        self.synthesizer.load_voice_model(model)?;
+        self.body().load_voice_model(model)?;
         Ok(())
     }
 
-    pub(crate) fn unload_voice_model(&self, model_id: VoiceModelId) -> Result<()> {
-        self.synthesizer.unload_voice_model(model_id)?;
+    pub(crate) fn unload_voice_model(self, model_id: VoiceModelId) -> Result<()> {
+        self.body().unload_voice_model(model_id)?;
         Ok(())
     }
 
-    pub(crate) fn metas(&self) -> CString {
-        metas_to_json(&self.synthesizer.metas())
+    pub(crate) fn metas(self) -> CString {
+        metas_to_json(&self.body().metas())
     }
 }
 
 impl VoicevoxVoiceModelFile {
-    pub(crate) fn open(path: impl AsRef<Path>) -> Result<Self> {
+    pub(crate) fn open(path: impl AsRef<Path>) -> Result<NonNull<Self>> {
         let model = voicevox_core::blocking::VoiceModelFile::open(path)?;
-        Ok(Self { model })
+        Ok(Self::new(model))
     }
+}
 
-    pub(crate) fn metas(&self) -> CString {
-        metas_to_json(self.model.metas())
+#[ext(VoicevoxVoiceModelFilePtrExt)]
+impl *const VoicevoxVoiceModelFile {
+    pub(crate) fn metas(self) -> CString {
+        metas_to_json(self.body().metas())
     }
 }
 
 fn metas_to_json(metas: &[SpeakerMeta]) -> CString {
     let metas = serde_json::to_string(metas).expect("should not fail");
     CString::new(metas).expect("should not contain NUL")
 }
+
+#[duplicate_item(
+    H                          B;
+    [ OpenJtalkRc ]            [ voicevox_core::blocking::OpenJtalk ];
+    [ VoicevoxUserDict ]       [ voicevox_core::blocking::UserDict ];
+    [ VoicevoxSynthesizer ]    [ voicevox_core::blocking::Synthesizer<voicevox_core::blocking::OpenJtalk> ];
+    [ VoicevoxVoiceModelFile ] [ voicevox_core::blocking::VoiceModelFile ];
+)]
+impl CApiObject for H {
+    type RustApiObject = B;
+
+    fn heads() -> &'static std::sync::Mutex<Vec<Self>> {
+        static HEADS: std::sync::Mutex<Vec<H>> = std::sync::Mutex::new(vec![]);
+        &HEADS
+    }
+
+    fn bodies() -> &'static std::sync::Mutex<
+        HashMap<usize, Arc<parking_lot::RwLock<Option<Self::RustApiObject>>>>,
+    > {
+        #[expect(clippy::type_complexity, reason = "`CApiObject::bodies`と同様")]
+        static BODIES: LazyLock<
+            std::sync::Mutex<HashMap<usize, Arc<parking_lot::RwLock<Option<B>>>>>,
+        > = LazyLock::new(Default::default);
+
+        &BODIES
+    }
+}