core: Allow terminating an Isolate from another thread (denoland#1982)

core/isolate.rs

@@ -11,7 +11,7 @@ use futures::Poll;
 use libc::c_void;
 use std::ffi::CStr;
 use std::ffi::CString;
-use std::sync::{Once, ONCE_INIT};
+use std::sync::{Arc, Mutex, Once, ONCE_INIT};
 
 pub type Buf = Box<[u8]>;
 pub type Op = dyn Future<Item = Buf, Error = ()> + Send;
@@ -85,6 +85,7 @@ pub trait Behavior {
 /// JavaScript.
 pub struct Isolate<B: Behavior> {
   libdeno_isolate: *const libdeno::isolate,
+  shared_libdeno_isolate: Arc<Mutex<Option<*const libdeno::isolate>>>,
   behavior: B,
   needs_init: bool,
   shared: SharedQueue,
@@ -96,6 +97,9 @@ unsafe impl<B: Behavior> Send for Isolate<B> {}
 
 impl<B: Behavior> Drop for Isolate<B> {
   fn drop(&mut self) {
+    // remove shared_libdeno_isolate reference
+    *self.shared_libdeno_isolate.lock().unwrap() = None;
+
     unsafe { libdeno::deno_delete(self.libdeno_isolate) }
   }
 }
@@ -130,6 +134,7 @@ impl<B: Behavior> Isolate<B> {
 
     let mut core_isolate = Self {
       libdeno_isolate,
+      shared_libdeno_isolate: Arc::new(Mutex::new(Some(libdeno_isolate))),
       behavior,
       shared,
       needs_init,
@@ -148,6 +153,13 @@ impl<B: Behavior> Isolate<B> {
     core_isolate
   }
 
+  /// Get a thread safe handle on the isolate.
+  pub fn shared_isolate_handle(&mut self) -> IsolateHandle {
+    IsolateHandle {
+      shared_libdeno_isolate: self.shared_libdeno_isolate.clone(),
+    }
+  }
+
   /// Executes a bit of built-in JavaScript to provide Deno._sharedQueue.
   pub fn shared_init(&mut self) {
     if self.needs_init {
@@ -452,6 +464,28 @@ impl<B: Behavior> Future for Isolate<B> {
   }
 }
 
+/// IsolateHandle is a thread safe handle on an Isolate. It exposed thread safe V8 functions.
+#[derive(Clone)]
+pub struct IsolateHandle {
+  shared_libdeno_isolate: Arc<Mutex<Option<*const libdeno::isolate>>>,
+}
+
+unsafe impl Send for IsolateHandle {}
+
+impl IsolateHandle {
+  /// Terminate the execution of any currently running javascript.
+  /// After terminating execution it is probably not wise to continue using
+  /// the isolate.
+  pub fn terminate_execution(&self) {
+    unsafe {
+      match *self.shared_libdeno_isolate.lock().unwrap() {
+        Some(isolate) => libdeno::deno_terminate_execution(isolate),
+        None => (),
+      }
+    }
+  }
+}
+
 pub fn js_check(r: Result<(), JSError>) {
   if let Err(e) = r {
     panic!(e.to_string());
@@ -698,6 +732,76 @@ mod tests {
     js_check(isolate.execute("send1.js", "assert(nrecv === 2);"));
   }
 
+  #[test]
+  fn terminate_execution() {
+    let (tx, rx) = std::sync::mpsc::channel::<bool>();
+    let tx_clone = tx.clone();
+
+    let mut isolate = TestBehavior::setup(TestBehaviorMode::AsyncImmediate);
+    let shared = isolate.shared_isolate_handle();
+
+    let t1 = std::thread::spawn(move || {
+      // allow deno to boot and run
+      std::thread::sleep(std::time::Duration::from_millis(100));
+
+      // terminate execution
+      shared.terminate_execution();
+
+      // allow shutdown
+      std::thread::sleep(std::time::Duration::from_millis(100));
+
+      // unless reported otherwise the test should fail after this point
+      tx_clone.send(false).ok();
+    });
+
+    let t2 = std::thread::spawn(move || {
+      // run an infinite loop
+      let res = isolate.execute(
+        "infinite_loop.js",
+        r#"
+          let i = 0;
+          while (true) { i++; }
+        "#,
+      );
+
+      // execute() terminated, which means terminate_execution() was successful.
+      tx.send(true).ok();
+
+      if let Err(e) = res {
+        assert_eq!(e.to_string(), "Uncaught Error: execution terminated");
+      } else {
+        panic!("should return an error");
+      }
+
+      // make sure the isolate is still unusable
+      let res = isolate.execute("simple.js", "1+1;");
+      if let Err(e) = res {
+        assert_eq!(e.to_string(), "Uncaught Error: execution terminated");
+      } else {
+        panic!("should return an error");
+      }
+    });
+
+    if !rx.recv().unwrap() {
+      panic!("should have terminated")
+    }
+
+    t1.join().unwrap();
+    t2.join().unwrap();
+  }
+
+  #[test]
+  fn dangling_shared_isolate() {
+    let shared = {
+      // isolate is dropped at the end of this block
+      let mut isolate = TestBehavior::setup(TestBehaviorMode::AsyncImmediate);
+      isolate.shared_isolate_handle()
+    };
+
+    // this should not SEGFAULT
+    shared.terminate_execution();
+  }
+
   #[test]
   fn overflow_req_sync() {
     let mut isolate = TestBehavior::setup(TestBehaviorMode::OverflowReqSync);

core/libdeno.rs

@@ -155,6 +155,7 @@ extern "C" {
     js_filename: *const c_char,
     js_source: *const c_char,
   );
+  pub fn deno_terminate_execution(i: *const isolate);
 
   // Modules
 

libdeno/exceptions.cc

@@ -174,6 +174,25 @@ std::string EncodeExceptionAsJSON(v8::Local<v8::Context> context,
 void HandleException(v8::Local<v8::Context> context,
                      v8::Local<v8::Value> exception) {
   v8::Isolate* isolate = context->GetIsolate();
+
+  // TerminateExecution was called
+  if (isolate->IsExecutionTerminating()) {
+    // cancel exception termination so that the exception can be created
+    isolate->CancelTerminateExecution();
+
+    // maybe make a new exception object
+    if (exception->IsNullOrUndefined()) {
+      exception = v8::Exception::Error(v8_str("execution terminated"));
+    }
+
+    // handle the exception as if it is a regular exception
+    HandleException(context, exception);
+
+    // re-enable exception termination
+    isolate->TerminateExecution();
+    return;
+  }
+
   DenoIsolate* d = DenoIsolate::FromIsolate(isolate);
   std::string json_str = EncodeExceptionAsJSON(context, exception);
   CHECK_NOT_NULL(d);
@@ -183,6 +202,13 @@ void HandleException(v8::Local<v8::Context> context,
 void HandleExceptionMessage(v8::Local<v8::Context> context,
                             v8::Local<v8::Message> message) {
   v8::Isolate* isolate = context->GetIsolate();
+
+  // TerminateExecution was called
+  if (isolate->IsExecutionTerminating()) {
+    HandleException(context, v8::Undefined(isolate));
+    return;
+  }
+
   DenoIsolate* d = DenoIsolate::FromIsolate(isolate);
   std::string json_str = EncodeMessageAsJSON(context, message);
   CHECK_NOT_NULL(d);