refactor usage of `Arc` (#595)

Accept generic construct instead of Arc to avoid nested arc required to bridge different crates. Also fix a missing export.
Signed-off-by: tabokie <xy.tao@outlook.com>

src/encryption.rs

@@ -69,19 +69,19 @@ fn copy_error<T: Into<Vec<u8>>>(err: T) -> *const c_char {
     unsafe { libc::strdup(cstr.as_ptr()) }
 }
 
-extern "C" fn encryption_key_manager_destructor(ctx: *mut c_void) {
+extern "C" fn encryption_key_manager_destructor<T: EncryptionKeyManager>(ctx: *mut c_void) {
     unsafe {
         // Recover from raw pointer and implicitly drop.
-        Box::from_raw(ctx as *mut Arc<dyn EncryptionKeyManager>);
+        Box::from_raw(ctx as *mut T);
     }
 }
 
-extern "C" fn encryption_key_manager_get_file(
+extern "C" fn encryption_key_manager_get_file<T: EncryptionKeyManager>(
     ctx: *mut c_void,
     fname: *const c_char,
     file_info: *mut DBFileEncryptionInfo,
 ) -> *const c_char {
-    let key_manager = unsafe { &*(ctx as *mut Arc<dyn EncryptionKeyManager>) };
+    let key_manager = unsafe { &*(ctx as *mut T) };
     let fname = match unsafe { CStr::from_ptr(fname).to_str() } {
         Ok(ret) => ret,
         Err(err) => {
@@ -102,12 +102,12 @@ extern "C" fn encryption_key_manager_get_file(
     }
 }
 
-extern "C" fn encryption_key_manager_new_file(
+extern "C" fn encryption_key_manager_new_file<T: EncryptionKeyManager>(
     ctx: *mut c_void,
     fname: *const c_char,
     file_info: *mut DBFileEncryptionInfo,
 ) -> *const c_char {
-    let key_manager = unsafe { &*(ctx as *mut Arc<dyn EncryptionKeyManager>) };
+    let key_manager = unsafe { &*(ctx as *mut T) };
     let fname = match unsafe { CStr::from_ptr(fname).to_str() } {
         Ok(ret) => ret,
         Err(err) => {
@@ -128,11 +128,11 @@ extern "C" fn encryption_key_manager_new_file(
     }
 }
 
-extern "C" fn encryption_key_manager_delete_file(
+extern "C" fn encryption_key_manager_delete_file<T: EncryptionKeyManager>(
     ctx: *mut c_void,
     fname: *const c_char,
 ) -> *const c_char {
-    let key_manager = unsafe { &*(ctx as *mut Arc<dyn EncryptionKeyManager>) };
+    let key_manager = unsafe { &*(ctx as *mut T) };
     let fname = match unsafe { CStr::from_ptr(fname).to_str() } {
         Ok(ret) => ret,
         Err(err) => {
@@ -151,12 +151,12 @@ extern "C" fn encryption_key_manager_delete_file(
     }
 }
 
-extern "C" fn encryption_key_manager_link_file(
+extern "C" fn encryption_key_manager_link_file<T: EncryptionKeyManager>(
     ctx: *mut c_void,
     src_fname: *const c_char,
     dst_fname: *const c_char,
 ) -> *const c_char {
-    let key_manager = unsafe { &*(ctx as *mut Arc<dyn EncryptionKeyManager>) };
+    let key_manager = unsafe { &*(ctx as *mut T) };
     let src_fname = match unsafe { CStr::from_ptr(src_fname).to_str() } {
         Ok(ret) => ret,
         Err(err) => {
@@ -192,18 +192,16 @@ unsafe impl Send for DBEncryptionKeyManager {}
 unsafe impl Sync for DBEncryptionKeyManager {}
 
 impl DBEncryptionKeyManager {
-    pub fn new(key_manager: Arc<dyn EncryptionKeyManager>) -> DBEncryptionKeyManager {
-        // Size of Arc<dyn T>::into_raw is of 128-bits, which couldn't be used as C-style pointer.
-        // Boxing it to make a 64-bits pointer.
+    pub fn new<T: EncryptionKeyManager>(key_manager: T) -> DBEncryptionKeyManager {
         let ctx = Box::into_raw(Box::new(key_manager)) as *mut c_void;
         let instance = unsafe {
             crocksdb_ffi::crocksdb_encryption_key_manager_create(
                 ctx,
-                encryption_key_manager_destructor,
-                encryption_key_manager_get_file,
-                encryption_key_manager_new_file,
-                encryption_key_manager_delete_file,
-                encryption_key_manager_link_file,
+                encryption_key_manager_destructor::<T>,
+                encryption_key_manager_get_file::<T>,
+                encryption_key_manager_new_file::<T>,
+                encryption_key_manager_delete_file::<T>,
+                encryption_key_manager_link_file::<T>,
             )
         };
         DBEncryptionKeyManager { inner: instance }
@@ -387,7 +385,7 @@ mod test {
         }
     }
 
-    impl EncryptionKeyManager for Mutex<TestEncryptionKeyManager> {
+    impl EncryptionKeyManager for Arc<Mutex<TestEncryptionKeyManager>> {
         fn get_file(&self, fname: &str) -> Result<FileEncryptionInfo> {
             let key_manager = self.lock().unwrap();
             key_manager.get_file_called.fetch_add(1, Ordering::SeqCst);

src/file_system.rs

@@ -3,7 +3,6 @@
 pub use crocksdb_ffi::{self, DBFileSystemInspectorInstance};
 
 use libc::{c_char, c_void, size_t, strdup};
-use std::sync::Arc;
 
 // Inspect global IO flow. No per-file inspection for now.
 pub trait FileSystemInspector: Sync + Send {
@@ -11,19 +10,19 @@ pub trait FileSystemInspector: Sync + Send {
     fn write(&self, len: usize) -> Result<usize, String>;
 }
 
-extern "C" fn file_system_inspector_destructor(ctx: *mut c_void) {
+extern "C" fn file_system_inspector_destructor<T: FileSystemInspector>(ctx: *mut c_void) {
     unsafe {
         // Recover from raw pointer and implicitly drop.
-        Box::from_raw(ctx as *mut Arc<dyn FileSystemInspector>);
+        Box::from_raw(ctx as *mut T);
     }
 }
 
-extern "C" fn file_system_inspector_read(
+extern "C" fn file_system_inspector_read<T: FileSystemInspector>(
     ctx: *mut c_void,
     len: size_t,
     errptr: *mut *mut c_char,
 ) -> size_t {
-    let file_system_inspector = unsafe { &*(ctx as *mut Arc<dyn FileSystemInspector>) };
+    let file_system_inspector = unsafe { &*(ctx as *mut T) };
     match file_system_inspector.read(len) {
         Ok(ret) => ret,
         Err(e) => {
@@ -35,12 +34,12 @@ extern "C" fn file_system_inspector_read(
     }
 }
 
-extern "C" fn file_system_inspector_write(
+extern "C" fn file_system_inspector_write<T: FileSystemInspector>(
     ctx: *mut c_void,
     len: size_t,
     errptr: *mut *mut c_char,
 ) -> size_t {
-    let file_system_inspector = unsafe { &*(ctx as *mut Arc<dyn FileSystemInspector>) };
+    let file_system_inspector = unsafe { &*(ctx as *mut T) };
     match file_system_inspector.write(len) {
         Ok(ret) => ret,
         Err(e) => {
@@ -60,16 +59,14 @@ unsafe impl Send for DBFileSystemInspector {}
 unsafe impl Sync for DBFileSystemInspector {}
 
 impl DBFileSystemInspector {
-    pub fn new(file_system_inspector: Arc<dyn FileSystemInspector>) -> DBFileSystemInspector {
-        // Size of Arc<dyn T>::into_raw is of 128-bits, which couldn't be used as C-style pointer.
-        // Boxing it to make a 64-bits pointer.
+    pub fn new<T: FileSystemInspector>(file_system_inspector: T) -> DBFileSystemInspector {
         let ctx = Box::into_raw(Box::new(file_system_inspector)) as *mut c_void;
         let instance = unsafe {
             crocksdb_ffi::crocksdb_file_system_inspector_create(
                 ctx,
-                file_system_inspector_destructor,
-                file_system_inspector_read,
-                file_system_inspector_write,
+                file_system_inspector_destructor::<T>,
+                file_system_inspector_read::<T>,
+                file_system_inspector_write::<T>,
             )
         };
         DBFileSystemInspector { inner: instance }
@@ -131,7 +128,7 @@ mod test {
         }
     }
 
-    impl FileSystemInspector for Mutex<TestFileSystemInspector> {
+    impl FileSystemInspector for Arc<Mutex<TestFileSystemInspector>> {
         fn read(&self, len: usize) -> Result<usize, String> {
             let mut inner = self.lock().unwrap();
             inner.read_called += 1;

src/lib.rs

@@ -41,6 +41,7 @@ pub use event_listener::{
     CompactionJobInfo, EventListener, FlushJobInfo, IngestionInfo, SubcompactionJobInfo,
     WriteStallInfo,
 };
+pub use file_system::FileSystemInspector;
 pub use librocksdb_sys::{
     self as crocksdb_ffi, new_bloom_filter, CompactionPriority, CompactionReason,
     DBBackgroundErrorReason, DBBottommostLevelCompaction, DBCompactionStyle, DBCompressionType,

src/rocksdb.rs

@@ -2654,9 +2654,9 @@ impl Env {
 
     // Create an encrypted env that accepts an external key manager.
     #[cfg(feature = "encryption")]
-    pub fn new_key_managed_encrypted_env(
+    pub fn new_key_managed_encrypted_env<T: EncryptionKeyManager>(
         base_env: Arc<Env>,
-        key_manager: Arc<dyn EncryptionKeyManager>,
+        key_manager: T,
     ) -> Result<Env, String> {
         let db_key_manager = DBEncryptionKeyManager::new(key_manager);
         let env = unsafe {
@@ -2671,9 +2671,9 @@ impl Env {
         })
     }
 
-    pub fn new_file_system_inspected_env(
+    pub fn new_file_system_inspected_env<T: FileSystemInspector>(
         base_env: Arc<Env>,
-        file_system_inspector: Arc<dyn FileSystemInspector>,
+        file_system_inspector: T,
     ) -> Result<Env, String> {
         let db_file_system_inspector = DBFileSystemInspector::new(file_system_inspector);
         let env = unsafe {