feat(java): callback API

Co-authored-by: alemi <me@alemi.dev>

dist/java/src/mp/code/Extensions.java

@@ -0,0 +1,17 @@
+package mp.code;
+
+public class Extensions {
+	/**
+	 * Hashes the given {@link String} using CodeMP's hashing algorithm (xxh3).
+	 * @param input the string to hash
+	 * @return the hash
+	 */
+	public static native long hash(String input);
+
+	/**
+	 * Drive the underlying library's asynchronous event loop.
+	 * @param block true if it should use the current thread, false if it should
+	 *              spawn a separate one
+	 */
+	public static native void drive(boolean block);
+}

dist/java/src/mp/code/Utils.java

@@ -1,10 +0,0 @@
-package mp.code;
-
-public class Utils {
-	/**
-	 * Hashes the given {@link String} using CodeMP's hashing algorithm (xxh3).
-	 * @param input the string to hash
-	 * @return the hash
-	 */
-	public static native long hash(String input);
-}

src/ffi/java/buffer.rs

@@ -1,8 +1,8 @@
 use jni::{objects::{JClass, JObject, JValueGen}, sys::{jlong, jobject, jstring}, JNIEnv};
 
-use crate::{api::Controller, ffi::java::handle_callback};
+use crate::api::Controller;
 
-use super::{JExceptable, RT};
+use super::JExceptable;
 
 /// Gets the name of the buffer. 
 #[no_mangle]
@@ -26,7 +26,7 @@ pub extern "system" fn Java_mp_code_BufferController_get_1content(
 	self_ptr: jlong,
 ) -> jstring {
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) };
-	let content = RT.block_on(controller.content())
+	let content = super::tokio().block_on(controller.content())
 		.jexcept(&mut env);
 	env.new_string(content)
 		.jexcept(&mut env)
@@ -41,7 +41,7 @@ pub extern "system" fn Java_mp_code_BufferController_try_1recv(
 	self_ptr: jlong,
 ) -> jobject {
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) };
-	let change = RT.block_on(controller.try_recv()).jexcept(&mut env);
+	let change = super::tokio().block_on(controller.try_recv()).jexcept(&mut env);
 	recv_jni(&mut env, change)
 }
 
@@ -53,7 +53,7 @@ pub extern "system" fn Java_mp_code_BufferController_recv(
 	self_ptr: jlong,
 ) -> jobject {
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) };
-	let change = RT.block_on(controller.recv()).map(Some).jexcept(&mut env);
+	let change = super::tokio().block_on(controller.recv()).map(Some).jexcept(&mut env);
 	recv_jni(&mut env, change)
 }
 
@@ -88,6 +88,18 @@ fn recv_jni(env: &mut JNIEnv, change: Option<crate::api::TextChange>) -> jobject
 	}.as_raw()
 }
 
+/// Clears the callback for buffer changes.
+#[no_mangle]
+pub extern "system" fn Java_mp_code_BufferController_clear_1callback(
+	_env: JNIEnv,
+	_class: JClass,
+	self_ptr: jlong,
+) {
+	unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) }
+		.clear_callback();
+}
+
+/// Registers a callback for buffer changes.
 #[no_mangle]
 pub extern "system" fn Java_mp_code_BufferController_callback<'local>(
 	mut env: JNIEnv,
@@ -95,7 +107,36 @@ pub extern "system" fn Java_mp_code_BufferController_callback<'local>(
 	self_ptr: jlong,
 	cb: JObject<'local>,
 ) {
-	handle_callback!("mp/code/BufferController", env, self_ptr, cb, crate::buffer::Controller);
+	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) };
+	
+	let Ok(cb_ref) = env.new_global_ref(cb) else {
+		env.throw_new("mp/code/exceptions/JNIException", "Failed to pin callback reference!")
+			.expect("Failed to throw exception!");
+		return;
+	};
+
+	controller.callback(move |controller: crate::buffer::Controller| {
+		let jvm = super::jvm();
+		let mut env = jvm.attach_current_thread_permanently()
+			.expect("failed attaching to main JVM thread");
+		if let Err(e) = env.with_local_frame(5, |env| {
+			use crate::ffi::java::JObjectify;
+			let jcontroller = controller.jobjectify(env)?;
+			let sig = format!("(L{};)V", "java/lang/Object");
+			if let Err(e) = env.call_method(
+				&cb_ref,
+				"invoke",
+				&sig,
+				&[jni::objects::JValueGen::Object(&jcontroller)]
+			) {
+				tracing::error!("error invoking callback: {e:?}");
+			};
+			Ok::<(), jni::errors::Error>(())
+		}) {
+			tracing::error!("error invoking callback: {e}");
+			let _ = env.exception_describe();
+		}
+	});
 }
 
 /// Receive from Java, converts and sends a [crate::api::TextChange].
@@ -147,7 +188,7 @@ pub extern "system" fn Java_mp_code_BufferController_send<'local>(
 		}).jexcept(&mut env);
 
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::buffer::Controller)) };
-	RT.block_on(controller.send(crate::api::TextChange {
+	super::tokio().block_on(controller.send(crate::api::TextChange {
 		start,
 		end,
 		content,

src/ffi/java/client.rs

@@ -1,7 +1,7 @@
 use jni::{objects::{JClass, JObject, JString, JValueGen}, sys::{jboolean, jint, jlong, jobject, jobjectArray}, JNIEnv};
 use crate::{api::Config, client::Client, Workspace};
 
-use super::{JExceptable, JObjectify, RT};
+use super::{JExceptable, JObjectify};
 
 /// Connect using the given credentials to the default server, and return a [Client] to interact with it.
 #[no_mangle]
@@ -63,7 +63,7 @@ pub extern "system" fn Java_mp_code_Client_connectToServer<'local>(
 }
 
 fn connect_internal(mut env: JNIEnv, config: Config) -> jobject {
-	RT.block_on(Client::connect(config))
+	super::tokio().block_on(Client::connect(config))
 		.map(|client| Box::into_raw(Box::new(client)) as jlong)
 		.map(|ptr| {
 			env.find_class("mp/code/Client")
@@ -98,7 +98,7 @@ pub extern "system" fn Java_mp_code_Client_join_1workspace<'local>(
 	let workspace_id = unsafe { env.get_string_unchecked(&input) }
 		.map(|wid| wid.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	RT.block_on(client.join_workspace(workspace_id))
+	super::tokio().block_on(client.join_workspace(workspace_id))
 		.map(|workspace| spawn_updater(workspace.clone()))
 		.map(|workspace| Box::into_raw(Box::new(workspace)) as jlong)
 		.map(|ptr| {
@@ -120,7 +120,7 @@ pub extern "system" fn Java_mp_code_Client_create_1workspace<'local>(
 	let workspace_id = unsafe { env.get_string_unchecked(&input) }
 		.map(|wid| wid.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	RT
+	super::tokio()
 		.block_on(client.create_workspace(workspace_id))
 		.jexcept(&mut env);
 }
@@ -137,7 +137,7 @@ pub extern "system" fn Java_mp_code_Client_delete_1workspace<'local>(
 	let workspace_id = unsafe { env.get_string_unchecked(&input) }
 		.map(|wid| wid.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	RT
+	super::tokio()
 		.block_on(client.delete_workspace(workspace_id))
 		.jexcept(&mut env);
 }
@@ -158,7 +158,7 @@ pub extern "system" fn Java_mp_code_Client_invite_1to_1workspace<'local>(
 	let user_name = unsafe { env.get_string_unchecked(&usr) }
 		.map(|wid| wid.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	RT
+	super::tokio()
 		.block_on(client.invite_to_workspace(workspace_id, user_name))
 		.jexcept(&mut env);
 }
@@ -173,7 +173,7 @@ pub extern "system" fn Java_mp_code_Client_list_1workspaces<'local>(
 	invited: jboolean
 ) -> jobjectArray {
 	let client = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Client)) };
-	let list = RT
+	let list = super::tokio()
 		.block_on(client.list_workspaces(owned != 0, invited != 0))
 		.jexcept(&mut env);
 	env.find_class("java/lang/String")
@@ -210,7 +210,7 @@ pub extern "system" fn Java_mp_code_Client_active_1workspaces<'local>(
 // TODO: this stays until we get rid of the arc then i'll have to find a better way
 fn spawn_updater(workspace: Workspace) -> Workspace {
 	let w = workspace.clone();
-	RT.spawn(async move {
+	super::tokio().spawn(async move {
 		loop {
 			tokio::time::sleep(std::time::Duration::from_secs(60)).await;
 			w.fetch_buffers().await.unwrap();
@@ -264,7 +264,7 @@ pub extern "system" fn Java_mp_code_Client_refresh<'local>(
 	self_ptr: jlong,
 ) {
 	let client = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Client)) };
-	RT.block_on(client.refresh())
+	super::tokio().block_on(client.refresh())
 		.jexcept(&mut env);
 }
 

src/ffi/java/cursor.rs

@@ -1,7 +1,7 @@
 use jni::{objects::{JClass, JObject, JString, JValueGen}, sys::{jlong, jobject}, JNIEnv};
 use crate::api::Controller;
 
-use super::{handle_callback, JExceptable, RT};
+use super::JExceptable;
 
 /// Try to fetch a [crate::api::Cursor], or returns null if there's nothing.
 #[no_mangle]
@@ -11,7 +11,7 @@ pub extern "system" fn Java_mp_code_CursorController_try_1recv(
 	self_ptr: jlong,
 ) -> jobject {
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::cursor::Controller)) };
-	let cursor = RT.block_on(controller.try_recv()).jexcept(&mut env);
+	let cursor = super::tokio().block_on(controller.try_recv()).jexcept(&mut env);
 	jni_recv(&mut env, cursor)
 }
 
@@ -23,7 +23,7 @@ pub extern "system" fn Java_mp_code_CursorController_recv(
 	self_ptr: jlong,
 ) -> jobject {
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::cursor::Controller)) };
-	let cursor = RT.block_on(controller.recv()).map(Some).jexcept(&mut env);
+	let cursor = super::tokio().block_on(controller.recv()).map(Some).jexcept(&mut env);
 	jni_recv(&mut env, cursor)
 }
 
@@ -56,6 +56,18 @@ fn jni_recv(env: &mut JNIEnv, cursor: Option<crate::api::Cursor>) -> jobject {
 	}.as_raw()
 }
 
+/// Clears the callback for cursor changes.
+#[no_mangle]
+pub extern "system" fn Java_mp_code_CursorController_clear_1callback(
+	_env: JNIEnv,
+	_class: JClass,
+	self_ptr: jlong,
+) {
+	unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::cursor::Controller)) }
+		.clear_callback();
+}
+
+/// Registers a callback for cursor changes.
 #[no_mangle]
 pub extern "system" fn Java_mp_code_CursorController_callback<'local>(
 	mut env: JNIEnv,
@@ -63,7 +75,36 @@ pub extern "system" fn Java_mp_code_CursorController_callback<'local>(
 	self_ptr: jlong,
 	cb: JObject<'local>,
 ) {
-	handle_callback!("mp/code/CursorController", env, self_ptr, cb, crate::cursor::Controller);
+	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::cursor::Controller)) };
+	
+	let Ok(cb_ref) = env.new_global_ref(cb) else {
+		env.throw_new("mp/code/exceptions/JNIException", "Failed to pin callback reference!")
+			.expect("Failed to throw exception!");
+		return;
+	};
+
+	controller.callback(move |controller: crate::cursor::Controller| {
+		let jvm = super::jvm();
+		let mut env = jvm.attach_current_thread_permanently()
+			.expect("failed attaching to main JVM thread");
+		if let Err(e) = env.with_local_frame(5, |env| {
+			use crate::ffi::java::JObjectify;
+			let jcontroller = controller.jobjectify(env)?;
+			let sig = format!("(L{};)V", "java/lang/Object");
+			if let Err(e) = env.call_method(
+				&cb_ref,
+				"invoke",
+				&sig,
+				&[jni::objects::JValueGen::Object(&jcontroller)]
+			) {
+				tracing::error!("error invoking callback: {e:?}");
+			};
+			Ok::<(), jni::errors::Error>(())
+		}) {
+			tracing::error!("error invoking callback: {e}");
+			let _ = env.exception_describe();
+		}
+	});
 }
 
 /// Receive from Java, converts and sends a [crate::api::Cursor].
@@ -109,7 +150,7 @@ pub extern "system" fn Java_mp_code_CursorController_send<'local>(
 	};
 
 	let controller = unsafe { Box::leak(Box::from_raw(self_ptr as *mut crate::cursor::Controller)) };
-	RT.block_on(controller.send(crate::api::Cursor {
+	super::tokio().block_on(controller.send(crate::api::Cursor {
 		start: (start_row, start_col),
 		end: (end_row, end_col),
 		buffer,

src/ffi/java/ext.rs

@@ -0,0 +1,34 @@
+use jni::{objects::{JClass, JString}, sys::{jboolean, jlong}, JNIEnv};
+
+use super::JExceptable;
+
+/// Calculate the XXH3 hash for a given String.
+#[no_mangle]
+pub extern "system" fn Java_mp_code_Extensions_hash<'local>(
+	mut env: JNIEnv,
+	_class: JClass<'local>,
+	content: JString<'local>,
+) -> jlong {
+	let content: String = env.get_string(&content)
+		.map(|s| s.into())
+		.jexcept(&mut env);
+	let hash = crate::ext::hash(content.as_bytes());
+	i64::from_ne_bytes(hash.to_ne_bytes())
+}
+
+/// Tells the [tokio] runtime how to drive the event loop.
+#[no_mangle]
+pub extern "system" fn Java_mp_code_Extensions_drive(
+	_env: JNIEnv,
+	_class: JClass,
+	block: jboolean
+) {
+	if block != 0 {
+		super::tokio().block_on(std::future::pending::<()>());
+	} else {
+		std::thread::spawn(|| {
+			super::tokio().block_on(std::future::pending::<()>());
+		});
+	}
+}
+

src/ffi/java/mod.rs

@@ -2,10 +2,37 @@ pub mod client;
 pub mod workspace;
 pub mod cursor;
 pub mod buffer;
-pub mod utils;
+pub mod ext;
 
-lazy_static::lazy_static! {
+/// Gets or creates the relevant [tokio::runtime::Runtime].
-	pub(crate) static ref RT: tokio::runtime::Runtime = tokio::runtime::Runtime::new().expect("could not create tokio runtime");
+fn tokio() -> &'static tokio::runtime::Runtime {
+	use std::sync::OnceLock;
+	static RT: OnceLock<tokio::runtime::Runtime> = OnceLock::new();
+	RT.get_or_init(||
+		tokio::runtime::Builder::new_current_thread()
+			.enable_all()
+			.build()
+			.expect("could not create tokio runtime")
+	)
+}
+
+/// A static reference to [jni::JavaVM] that is set on JNI load.
+static mut JVM: Option<std::sync::Arc<jni::JavaVM>> = None;
+
+/// Safe accessor for the [jni::JavaVM] static.
+pub(crate) fn jvm() -> std::sync::Arc<jni::JavaVM> {
+	unsafe { JVM.clone() }.unwrap()
+}
+
+/// Called upon initialisation of the JVM.
+#[allow(non_snake_case)]
+#[no_mangle]
+pub extern "system" fn JNI_OnLoad(
+	vm: jni::JavaVM,
+	_: *mut std::ffi::c_void
+) -> jni::sys::jint {
+	unsafe { JVM = Some(std::sync::Arc::new(vm)) };
+	jni::sys::JNI_VERSION_1_1
 }
 
 /// Set up logging. Useful for debugging.
@@ -149,7 +176,7 @@ impl<'local> JObjectify<'local> for crate::cursor::Controller {
 			class,
 			"(J)V",
 			&[
-				jni::objects::JValueGen::Long(Box::into_raw(Box::new(&self)) as jni::sys::jlong)
+				jni::objects::JValueGen::Long(Box::into_raw(Box::new(self)) as jni::sys::jlong)
 			]
 		)
 	}
@@ -164,46 +191,8 @@ impl<'local> JObjectify<'local> for crate::buffer::Controller {
 			class,
 			"(J)V",
 			&[
-				jni::objects::JValueGen::Long(Box::into_raw(Box::new(&self)) as jni::sys::jlong)
+				jni::objects::JValueGen::Long(Box::into_raw(Box::new(self)) as jni::sys::jlong)
 			]
 		)
 	}
 }
-
-macro_rules! handle_callback {
-	($jtype:literal, $env:ident, $self_ptr:ident, $cb:ident, $t:ty) => {
-		let controller = unsafe { Box::leak(Box::from_raw($self_ptr as *mut $t)) };
-		
-		let Ok(jvm) = $env.get_java_vm() else {
-			$env.throw_new("mp/code/exceptions/JNIException", "Failed to get JVM reference!")
-				.expect("Failed to throw exception!");
-			return;
-		};
-
-		let Ok(cb_ref) = $env.new_global_ref($cb) else {
-			$env.throw_new("mp/code/exceptions/JNIException", "Failed to pin callback reference!")
-				.expect("Failed to throw exception!");
-			return;
-		};
-		controller.callback(move |controller: $t| {
-			use std::ops::DerefMut;
-			use crate::ffi::java::JObjectify;
-			let mut guard = jvm.attach_current_thread().unwrap();
-			let jcontroller = match controller.jobjectify(guard.deref_mut()) {
-				Err(e) => return tracing::error!("could not convert callback argument: {e:?}"),
-				Ok(x) => x,
-			};
-			let sig = format!("(L{};)V", $jtype);
-			if let Err(e) = guard.call_method(&cb_ref,
-				"invoke",
-				&sig,
-				&[jni::objects::JValueGen::Object(&jcontroller)]
-			) {
-				tracing::error!("error invoking callback: {e:?}");
-			}
-		});
-	};
-}
-
-pub(crate) use handle_callback;
-

src/ffi/java/utils.rs

@@ -1,17 +0,0 @@
-use jni::{objects::{JClass, JString}, sys::jlong, JNIEnv};
-
-use super::JExceptable;
-
-/// Calculate the XXH3 hash for a given String.
-#[no_mangle]
-pub extern "system" fn Java_mp_code_Utils_hash<'local>(
-	mut env: JNIEnv,
-	_class: JClass<'local>,
-	content: JString<'local>,
-) -> jlong {
-	let content: String = env.get_string(&content)
-		.map(|s| s.into())
-		.jexcept(&mut env);
-	let hash = crate::ext::hash(content.as_bytes());
-	i64::from_ne_bytes(hash.to_ne_bytes())
-}

src/ffi/java/workspace.rs

@@ -1,7 +1,7 @@
 use jni::{objects::{JClass, JObject, JString, JValueGen}, sys::{jboolean, jlong, jobject, jobjectArray, jstring}, JNIEnv};
 use crate::Workspace;
 
-use super::{JExceptable, JObjectify, RT};
+use super::{JExceptable, JObjectify};
 
 /// Get the workspace id.
 #[no_mangle]
@@ -55,7 +55,7 @@ pub extern "system" fn Java_mp_code_Workspace_create_1buffer<'local>(
 	let path = unsafe { env.get_string_unchecked(&input) }
 		.map(|path| path.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	RT.block_on(ws.create(&path))
+	super::tokio().block_on(ws.create(&path))
 		.jexcept(&mut env);
 }
 
@@ -103,7 +103,7 @@ pub extern "system" fn Java_mp_code_Workspace_attach_1to_1buffer<'local>(
 	let path = unsafe { env.get_string_unchecked(&input) }
 		.map(|path| path.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	RT.block_on(workspace.attach(&path))
+	super::tokio().block_on(workspace.attach(&path))
 		.map(|buffer| buffer.jobjectify(&mut env).jexcept(&mut env))
 		.jexcept(&mut env)
 		.as_raw()
@@ -142,7 +142,7 @@ pub extern "system" fn Java_mp_code_Workspace_fetch_1buffers(
 	self_ptr: jlong,
 ) {
 	let workspace = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Workspace)) };
-	RT.block_on(workspace.fetch_buffers()).jexcept(&mut env);
+	super::tokio().block_on(workspace.fetch_buffers()).jexcept(&mut env);
 }
 
 /// Update the local user list.
@@ -153,7 +153,7 @@ pub extern "system" fn Java_mp_code_Workspace_fetch_1users(
 	self_ptr: jlong,
 ) {
 	let workspace = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Workspace)) };
-	RT.block_on(workspace.fetch_users()).jexcept(&mut env);
+	super::tokio().block_on(workspace.fetch_users()).jexcept(&mut env);
 }
 
 /// List users attached to a buffer.
@@ -168,7 +168,7 @@ pub extern "system" fn Java_mp_code_Workspace_list_1buffer_1users<'local>(
 	let buffer = unsafe { env.get_string_unchecked(&input) }
 		.map(|buffer| buffer.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	let users = RT.block_on(workspace.list_buffer_users(&buffer))
+	let users = super::tokio().block_on(workspace.list_buffer_users(&buffer))
 		.jexcept(&mut env);
 
 	env.find_class("java/util/UUID")
@@ -194,7 +194,7 @@ pub extern "system" fn Java_mp_code_Workspace_delete_1buffer<'local>(
 	let buffer = unsafe { env.get_string_unchecked(&input) }
 		.map(|buffer| buffer.to_string_lossy().to_string())
 		.jexcept(&mut env);
-	RT.block_on(workspace.delete(&buffer))
+	super::tokio().block_on(workspace.delete(&buffer))
 		.jexcept(&mut env);
 }
 
@@ -206,7 +206,7 @@ pub extern "system" fn Java_mp_code_Workspace_event(
 	self_ptr: jlong
 ) -> jobject {
 	let workspace = unsafe { Box::leak(Box::from_raw(self_ptr as *mut Workspace)) };
-	RT.block_on(workspace.event())
+	super::tokio().block_on(workspace.event())
 		.map(|event| {
 			let (name, arg) = match event {
 				crate::api::Event::FileTreeUpdated(arg) => ("FILE_TREE_UPDATED", env.new_string(arg).unwrap_or_default()),
@@ -247,10 +247,10 @@ pub extern "system" fn Java_mp_code_Workspace_select_1buffer(
 		}
 	}
 
-	RT.block_on(crate::ext::select_buffer(
+	super::tokio().block_on(crate::ext::select_buffer(
 		&controllers,
 		Some(std::time::Duration::from_millis(timeout as u64)),
-		&RT,
+		super::tokio(),
 	)).jexcept(&mut env)
 		.map(|buf| {
 			env.find_class("mp/code/BufferController").and_then(|class|