support res.removeListener('drain'), res.once('drain')

index.js

@@ -63,9 +63,39 @@ function compression (options) {
     var stream
 
     var _end = res.end
-    var _on = res.on
     var _write = res.write
 
+    // proxy drain events from stream
+    var _addListener = interceptAddListener(res, function (type, listener) {
+      if (!listeners || type !== 'drain') {
+        // skip intercept
+        return false
+      } else if (stream) {
+        // add listener to stream instead
+        stream.on(type, listener)
+      } else {
+        // buffer listeners for future stream
+        listeners.push([type, listener])
+      }
+    })
+
+    interceptRemoveListener(res, function (type, listener) {
+      if (!listeners || type !== 'drain') {
+        // skip intercept
+        return false
+      } else if (stream) {
+        // remove listener from stream
+        stream.removeListener(type, listener)
+      } else {
+        // remove buffered listener
+        for (var i = listeners.length - 1; i >= 0; i--) {
+          if (listeners[i][0] === type && listeners[i][1] === listener) {
+            listeners.splice(i, 1)
+          }
+        }
+      }
+    })
+
     // flush
     res.flush = function flush () {
       if (stream) {
@@ -116,24 +146,9 @@ function compression (options) {
         : stream.end()
     }
 
-    res.on = function on (type, listener) {
-      if (!listeners || type !== 'drain') {
-        return _on.call(this, type, listener)
-      }
-
-      if (stream) {
-        return stream.on(type, listener)
-      }
-
-      // buffer listeners for future stream
-      listeners.push([type, listener])
-
-      return this
-    }
-
     function nocompress (msg) {
       debug('no compression: %s', msg)
-      addListeners(res, _on, listeners)
+      addListeners(res, _addListener, listeners)
       listeners = null
     }
 
@@ -212,7 +227,7 @@ function compression (options) {
         _end.call(res)
       })
 
-      _on.call(res, 'drain', function onResponseDrain () {
+      _addListener.call(res, 'drain', function onResponseDrain () {
         stream.resume()
       })
     })
@@ -226,9 +241,9 @@ function compression (options) {
  * @private
  */
 
-function addListeners (stream, on, listeners) {
+function addListeners (stream, addListener, listeners) {
   for (var i = 0; i < listeners.length; i++) {
-    on.apply(stream, listeners[i])
+    addListener.apply(stream, listeners[i])
   }
 }
 
@@ -246,6 +261,93 @@ function chunkLength (chunk, encoding) {
     : chunk.length
 }
 
+/**
+ * Intercept add listener on event emitter.
+ * @private
+ */
+
+function interceptAddListener (ee, fn) {
+  var _addListener = ee.addListener
+  var _on = ee.on
+
+  if (_addListener) {
+    Object.defineProperty(ee, 'addListener', {
+      configurable: true,
+      value: addListener,
+      writable: true
+    })
+  }
+
+  if (_on) {
+    Object.defineProperty(ee, 'on', {
+      configurable: true,
+      value: on,
+      writable: true
+    })
+  }
+
+  return _addListener || _on || noop
+
+  function addListener (type, listener) {
+    return fn.call(this, type, listener) === false
+      ? _addListener.call(this, type, listener)
+      : this
+  }
+
+  function on (type, listener) {
+    return fn.call(this, type, listener) === false
+      ? _on.call(this, type, listener)
+      : this
+  }
+}
+
+/**
+ * Intercept add listener on event emitter.
+ * @private
+ */
+
+function interceptRemoveListener (ee, fn) {
+  var _removeListener = ee.removeListener
+  var _off = ee.off
+
+  if (_removeListener) {
+    Object.defineProperty(ee, 'removeListener', {
+      configurable: true,
+      value: removeListener,
+      writable: true
+    })
+  }
+
+  if (_off) {
+    Object.defineProperty(ee, 'off', {
+      configurable: true,
+      value: off,
+      writable: true
+    })
+  }
+
+  return _removeListener || _off || noop
+
+  function removeListener (type, listener) {
+    return fn.call(this, type, listener) === false
+      ? _removeListener.call(this, type, listener)
+      : this
+  }
+
+  function off (type, listener) {
+    return fn.call(this, type, listener) === false
+      ? _off.call(this, type, listener)
+      : this
+  }
+}
+
+/**
+ * Reusable no-op function.
+ * @private
+ */
+
+function noop () {}
+
 /**
  * Default filter function.
  * @private

test/compression.js

@@ -305,6 +305,192 @@ describe('compression()', function () {
       .expect(200, done)
   })
 
+  it('should support removeListener("drain") after on("drain"); stream present', function (done) {
+    // compression doesn't proxy listenerCount() to the compression stream, so
+    // instead watch for a MaxListenersExceededWarning
+    var hasWarned = false
+    var onWarning = function () {
+      hasWarned = true
+    }
+    process.on('warning', onWarning)
+    var server = createServer({ threshold: 0 }, function (req, res) {
+      res.setHeader('Content-Type', 'text/plain')
+      var len = bytes('40kb')
+      var buf = Buffer.alloc(len, '.')
+      res.write(buf)
+      for (var times = 0; times < res.getMaxListeners() + 1; times++) {
+        var listener = function () {}
+        res.on('drain', listener)
+        res.removeListener('drain', listener)
+      }
+      res.end()
+    })
+
+    request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip')
+      .expect(function () {
+        process.removeListener('warning', onWarning)
+        assert.ok(!hasWarned)
+      })
+      .expect(200, done)
+  })
+
+  it('should support removeListener("drain") after addListener("drain")', function (done) {
+    var hasWarned = false
+    var onWarning = function () {
+      hasWarned = true
+    }
+    process.on('warning', onWarning)
+    var server = createServer({ threshold: 0 }, function (req, res) {
+      res.setHeader('Content-Type', 'text/plain')
+      var len = bytes('40kb')
+      var buf = Buffer.alloc(len, '.')
+      res.write(buf)
+      for (var times = 0; times < res.getMaxListeners() + 1; times++) {
+        var listener = function () {}
+        res.addListener('drain', listener)
+        res.removeListener('drain', listener)
+      }
+      res.end()
+    })
+
+    request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip')
+      .expect(function () {
+        process.removeListener('warning', onWarning)
+        assert.ok(!hasWarned)
+      })
+      .expect(200, done)
+  })
+
+  it('should support off("drain") after addListener("drain")', function (done) {
+    if (!require('events').EventEmitter.prototype.off) { // off was added in Node.js v10
+      this.skip()
+    }
+    var hasWarned = false
+    var onWarning = function () {
+      hasWarned = true
+    }
+    process.on('warning', onWarning)
+    var server = createServer({ threshold: 0 }, function (req, res) {
+      res.setHeader('Content-Type', 'text/plain')
+      var len = bytes('40kb')
+      var buf = Buffer.alloc(len, '.')
+      res.write(buf)
+      for (var times = 0; times < res.getMaxListeners() + 1; times++) {
+        var listener = function () {}
+        res.addListener('drain', listener)
+        res.off('drain', listener)
+      }
+      res.end()
+    })
+
+    request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip')
+      .expect(function () {
+        process.removeListener('warning', onWarning)
+        assert.ok(!hasWarned)
+      })
+      .expect(200, done)
+  })
+
+  it('should support removeListener("drain"); buffered', function (done) {
+    // Variant of above tests for scenario when the listener is buffered (stream
+    // is not yet present).
+    var hasWarned = false
+    var onWarning = function () {
+      hasWarned = true
+    }
+    process.on('warning', onWarning)
+    var server = createServer({ threshold: 0 }, function (req, res) {
+      res.setHeader('Content-Type', 'text/plain')
+      res.on('end', function () {})
+      for (var times = 0; times < res.getMaxListeners() + 1; times++) {
+        var listener = function () {}
+        res.on('drain', listener)
+        res.removeListener('drain', listener)
+      }
+      res.end()
+    })
+
+    request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip')
+      .expect(function () {
+        process.removeListener('warning', onWarning)
+        assert.ok(!hasWarned)
+      })
+      .expect(200, done)
+  })
+
+  it('should support removeListener("drain"); multiple bindings of same listener, buffered', function (done) {
+    // Variant of above test for scenario when the listener is buffered (stream
+    // is not yet present) and the same listener is added two or more times.
+    var hasWarned = false
+    var onWarning = function () {
+      hasWarned = true
+    }
+    process.on('warning', onWarning)
+    var server = createServer({ threshold: 0 }, function (req, res) {
+      res.setHeader('Content-Type', 'text/plain')
+      for (var times = 0; times < res.getMaxListeners() + 1; times++) {
+        var listener = function () {}
+        res.on('drain', listener)
+        res.on('drain', listener)
+        res.removeListener('drain', listener)
+      }
+      res.end()
+    })
+
+    request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip')
+      .expect(function () {
+        process.removeListener('warning', onWarning)
+        assert.ok(!hasWarned)
+      })
+      .expect(200, done)
+  })
+
+  it('should not leak event listeners when res.unpipe() is used (#135)', function (done) {
+    // unpipe and stream.Readable were added in v0.9.4
+    var stream = require('stream')
+    if (!(stream.Readable && stream.Readable.prototype.unpipe)) {
+      this.skip()
+    }
+
+    var hasWarned = false
+    var onWarning = function () {
+      hasWarned = true
+    }
+    var server = createServer({ threshold: 0 }, function (req, res) {
+      var times = 0
+      var int = setInterval(function () {
+        var rs = require('fs').createReadStream('does not exist')
+        rs.on('error', function (e) {
+          rs.unpipe(res)
+        })
+        rs.pipe(res)
+        if (times++ > res.getMaxListeners()) {
+          clearInterval(int)
+          res.end('hello, world')
+        }
+      })
+    })
+
+    request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip')
+      .expect(function () {
+        process.removeListener('warning', onWarning)
+        assert.ok(!hasWarned)
+      })
+      .expect(200, done)
+  })
+
   describe('threshold', function () {
     it('should not compress responses below the threshold size', function (done) {
       var server = createServer({ threshold: '1kb' }, function (req, res) {
@@ -669,6 +855,13 @@ function createServer (opts, fn) {
         return
       }
 
+      if (typeof res.getMaxListeners !== 'function') {
+        // Added in v0.11.2
+        res.getMaxListeners = function getMaxListeners () {
+          return 10
+        }
+      }
+
       fn(req, res)
     })
   })