fix: stop polling if the poller has an error

This will stop polling for FS events if there’s an error polling for fs events. Added tests for the JS. Tests for the c++ are harder.

packages/bindings/lib/poller.js

@@ -1,12 +1,12 @@
 const debug = require('debug')
 const logger = debug('serialport/bindings/poller')
 const EventEmitter = require('events')
-const FDPoller = require('bindings')('bindings.node').Poller
+const PollerBindings = require('bindings')('bindings.node').Poller
 
 const EVENTS = {
-  UV_READABLE: 1,
-  UV_WRITABLE: 2,
-  UV_DISCONNECT: 4,
+  UV_READABLE: 0b0001,
+  UV_WRITABLE: 0b0010,
+  UV_DISCONNECT: 0b0100,
 }
 
 function handleEvent(error, eventFlag) {
@@ -35,7 +35,7 @@ function handleEvent(error, eventFlag) {
  * Polls unix systems for readable or writable states of a file or serialport
  */
 class Poller extends EventEmitter {
-  constructor(fd) {
+  constructor(fd, FDPoller = PollerBindings) {
     logger('Creating poller')
     super()
     this.poller = new FDPoller(fd, handleEvent.bind(this))

packages/bindings/lib/poller.test.js

@@ -0,0 +1,60 @@
+const Poller = require('./poller')
+
+class MockPollerBidnings {
+  constructor(fd, callback) {
+    this.fd = fd
+    this.callback = callback
+  }
+  poll(flag) {
+    this.lastPollFlag = flag
+    setImmediate(() => this.callback(null, flag))
+  }
+}
+
+class ErrorPollerBindings {
+  constructor(fd, callback) {
+    this.fd = fd
+    this.callback = callback
+  }
+  poll(flag) {
+    this.lastPollFlag = flag
+    setImmediate(() => this.callback(new Error('oh no!'), flag))
+  }
+}
+
+describe('Poller', () => {
+  it('constructs', () => {
+    new Poller(1, MockPollerBidnings)
+  })
+  it('can listen to the readable event', done => {
+    const poller = new Poller(1, MockPollerBidnings)
+    poller.once('readable', err => {
+      assert.equal(err, null)
+      assert.equal(poller.poller.lastPollFlag, 1)
+      done(err)
+    })
+  })
+  it('can listen to the writable event', done => {
+    const poller = new Poller(1, MockPollerBidnings)
+    poller.once('writable', err => {
+      assert.equal(err, null)
+      assert.equal(poller.poller.lastPollFlag, 2)
+      done(err)
+    })
+  })
+  it('can listen to the disconnect event', done => {
+    const poller = new Poller(1, MockPollerBidnings)
+    poller.once('disconnect', err => {
+      assert.equal(err, null)
+      assert.equal(poller.poller.lastPollFlag, 4)
+      done(err)
+    })
+  })
+  it('reports errors on callback', done => {
+    const poller = new Poller(1, ErrorPollerBindings)
+    poller.once('readable', err => {
+      assert.notEqual(err, null)
+      done()
+    })
+  })
+})

packages/bindings/src/poller.cpp

@@ -49,22 +49,29 @@ void Poller::stop() {
   }
 }
 
+int Poller::_stop() {
+  return uv_poll_stop(poll_handle);
+}
+
 void Poller::onData(uv_poll_t* handle, int status, int events) {
   Nan::HandleScope scope;
   Poller* obj = static_cast<Poller*>(handle->data);
   v8::Local<v8::Value> argv[2];
+
+  // if Error
   if (0 != status) {
     // fprintf(stdout, "OnData Error status=%s events=%d\n", uv_strerror(status), events);
     argv[0] = v8::Exception::Error(Nan::New<v8::String>(uv_strerror(status)).ToLocalChecked());
     argv[1] = Nan::Undefined();
+    obj->_stop(); // doesn't matter if this errors
   } else {
     // fprintf(stdout, "OnData status=%d events=%d\n", status, events);
     argv[0] = Nan::Null();
     argv[1] = Nan::New<v8::Integer>(events);
+    // remove triggered events from the poll
+    int newEvents = obj->events & ~events;
+    obj->poll(newEvents);
   }
-  // remove triggered events from the poll
-  int newEvents = obj->events & ~events;
-  obj->poll(newEvents);
 
   obj->callback.Call(2, argv, obj);
 }

packages/bindings/src/poller.h

@@ -22,6 +22,7 @@ class Poller : public Nan::ObjectWrap, public Nan::AsyncResource {
   ~Poller();
   void poll(int events);
   void stop();
+  int _stop();
 
   static NAN_METHOD(New);
   static NAN_METHOD(poll);