reduce listeners added to pipelining socket

index.js

@@ -94,8 +94,6 @@ function attachFinishedListener (msg, callback) {
 
   function onFinish (error) {
     eeMsg.cancel()
-    eeSocket.cancel()
-
     finished = true
     callback(error)
   }
@@ -110,8 +108,13 @@ function attachFinishedListener (msg, callback) {
     if (finished) return
     if (eeMsg !== eeSocket) return
 
+    var attached = socket.__onFinished
+    if (!attached || !attached.queue) {
+      attached = socket.__onFinished = createListener(socket)
+      eeSocket = first([[socket, 'error', 'close']], attached)
+    }
     // finished on first socket event
-    eeSocket = first([[socket, 'error', 'close']], onFinish)
+    attached.queue.push(onFinish)
   }
 
   if (msg.socket) {

test/test.js

@@ -190,14 +190,12 @@ describe('onFinished(res, listener)', function () {
   describe('when calling many times on same response', function () {
     it('should not print warnings', function (done) {
       var server = http.createServer(function (req, res) {
-        var stderr = captureStderr(function () {
-          for (var i = 0; i < 400; i++) {
-            onFinished(res, noop)
-          }
-        })
-
+        var stderr = captureStderr()
+        for (var i = 0; i < 400; i++) {
+          onFinished(res, noop)
+        }
         onFinished(res, done)
-        assert.strictEqual(stderr, '')
+        assert.strictEqual(stderr(), '')
         res.end()
       })
 
@@ -537,14 +535,12 @@ describe('onFinished(req, listener)', function () {
   describe('when calling many times on same request', function () {
     it('should not print warnings', function (done) {
       var server = http.createServer(function (req, res) {
-        var stderr = captureStderr(function () {
-          for (var i = 0; i < 400; i++) {
-            onFinished(req, noop)
-          }
-        })
-
+        var stderr = captureStderr()
+        for (var i = 0; i < 400; i++) {
+          onFinished(req, noop)
+        }
         onFinished(req, done)
-        assert.strictEqual(stderr, '')
+        assert.strictEqual(stderr(), '')
         res.end()
       })
 
@@ -558,6 +554,38 @@ describe('onFinished(req, listener)', function () {
     })
   })
 
+  describe('when a client is pipelining requests', function () {
+    it('should not print warnings', function (done) {
+      var stderr = captureStderr()
+      var server = http.createServer(function (req, res) {
+        onFinished(req, noop)
+        res.end()
+      })
+      server.on('close', function () {
+        assert.strictEqual(stderr(), '')
+        done()
+      })
+      server.listen(function () {
+        var pipelineCount = 12
+        net.connect(this.address().port, function () {
+          var socket = this
+          for (var i = 0; i < pipelineCount; i++) {
+            writeRequest(this)
+          }
+          var responses = ''
+          var resRe = /HTTP\/1.1/g
+          socket.on('data', function (chunk) {
+            responses += chunk
+            if (responses.match(resRe).length === pipelineCount) {
+              socket.end()
+              server.close()
+            }
+          })
+        })
+      })
+    })
+  })
+
   describe('when CONNECT method', function () {
     it('should fire when request finishes', function (done) {
       var client
@@ -1031,21 +1059,18 @@ describe('isFinished(req)', function () {
   })
 })
 
-function captureStderr (fn) {
+function captureStderr () {
   var chunks = []
   var write = process.stderr.write
 
   process.stderr.write = function write (chunk, encoding) {
-    chunks.push(new Buffer(chunk, encoding)) // eslint-disable-line node/no-deprecated-api
+    chunks.push(Buffer.from ? Buffer.from(chunk, encoding) : new Buffer(chunk, encoding)) // eslint-disable-line node/no-deprecated-api
   }
 
-  try {
-    fn()
-  } finally {
+  return function restore () {
     process.stderr.write = write
+    return Buffer.concat(chunks).toString('utf8')
   }
-
-  return Buffer.concat(chunks).toString('utf8')
 }
 
 function close (server, callback) {