Prevent sequential errors from attempting multiple reconnections (#125)

* prevent sequential errors from attempting multiple reconnections.

* clean up test

Co-authored-by: davidpatty <dpatty@qualtrics.com>

lib/eventsource.js

@@ -45,6 +45,7 @@ function EventSource (url, eventSourceInitDict) {
 
   var self = this
   self.reconnectInterval = 1000
+  self.connectionInProgress = false
 
   function onConnectionClosed (message) {
     if (readyState === EventSource.CLOSED) return
@@ -58,9 +59,10 @@ function EventSource (url, eventSourceInitDict) {
       reconnectUrl = null
     }
     setTimeout(function () {
-      if (readyState !== EventSource.CONNECTING) {
+      if (readyState !== EventSource.CONNECTING || self.connectionInProgress) {
         return
       }
+      self.connectionInProgress = true
       connect()
     }, self.reconnectInterval)
   }
@@ -131,6 +133,7 @@ function EventSource (url, eventSourceInitDict) {
     }
 
     req = (isSecure ? https : http).request(options, function (res) {
+      self.connectionInProgress = false
       // Handle HTTP errors
       if (res.statusCode === 500 || res.statusCode === 502 || res.statusCode === 503 || res.statusCode === 504) {
         _emit('error', new Event('error', {status: res.statusCode, message: res.statusMessage}))

test/eventsource_test.js

@@ -873,6 +873,36 @@ describe('Reconnection', function () {
       }
     })
   })
+
+  it('attempts to reconnect are deduplicated on sequential erorrs', function (done) {
+    createServer(function (err, server) {
+      if (err) return done(err)
+      var events = ['data: Hello']
+      var eventsSent = 0
+      var errorOccurred = false
+      server.on('request', function (req, res) {
+        if (eventsSent === 0) {
+          var fn = writeEvents(events)
+          fn(req, res)
+          eventsSent++
+          // now cause a few errors
+          fn(req, res)
+          eventsSent++
+        } else {
+          assert.equal(EventSource.CONNECTING, es.readyState)
+          assert.ok(errorOccurred)
+          server.close(done)
+        }
+      })
+
+      var es = new EventSource(server.url)
+      assert.equal(EventSource.CONNECTING, es.readyState)
+      es.reconnectInterval = 0
+      es.onerror = function (err) {
+        errorOccurred = !!(errorOccurred || err)
+      }
+    })
+  })
 })
 
 describe('readyState', function () {