From ed51c3a16078719265efb7439e4e8cde93774cb0 Mon Sep 17 00:00:00 2001
From: Joe Podwys <joe@podwys.com>
Date: Sat, 7 May 2016 18:52:20 -0600
Subject: [PATCH 01/20] Update index.js

---
 index.js | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/index.js b/index.js
index c0e801e7..eed2a7fa 100644
--- a/index.js
+++ b/index.js
@@ -74,7 +74,7 @@ function compression (options) {
 
     // proxy
 
-    res.write = function write (chunk, encoding) {
+    res.write = function write (chunk, encoding, cb){
       if (ended) {
         return false
       }
@@ -84,19 +84,19 @@ function compression (options) {
       }
 
       return stream
-        ? stream.write(new Buffer(chunk, encoding))
-        : _write.call(this, chunk, encoding)
-    }
+        ? stream.write(new Buffer(chunk, encoding), cb)
+        : _write.call(this, chunk, encoding, cb)
+    };
 
-    res.end = function end (chunk, encoding) {
+    res.end = function end (chunk, encoding, cb){
       if (ended) {
         return false
       }
 
       if (!this._header) {
         // estimate the length
-        if (!this.getHeader('Content-Length')) {
-          length = chunkLength(chunk, encoding)
+        if (!this.getHeader('Content-Length'), cb) {
+          length = chunkLength(chunk, encoding, cb)
         }
 
         this._implicitHeader()

From f9c95f9821403ec734046bff7f4a14c25a64f12a Mon Sep 17 00:00:00 2001
From: Joe Podwys <joe@podwys.com>
Date: Sat, 7 May 2016 18:53:51 -0600
Subject: [PATCH 02/20] Update index.js

---
 index.js | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/index.js b/index.js
index eed2a7fa..552f602a 100644
--- a/index.js
+++ b/index.js
@@ -95,15 +95,15 @@ function compression (options) {
 
       if (!this._header) {
         // estimate the length
-        if (!this.getHeader('Content-Length'), cb) {
-          length = chunkLength(chunk, encoding, cb)
+        if (!this.getHeader('Content-Length')) {
+          length = chunkLength(chunk, encoding)
         }
 
         this._implicitHeader()
       }
 
       if (!stream) {
-        return _end.call(this, chunk, encoding)
+        return _end.call(this, chunk, encoding, cb)
       }
 
       // mark ended
@@ -111,8 +111,8 @@ function compression (options) {
 
       // write Buffer for Node.js 0.8
       return chunk
-        ? stream.end(new Buffer(chunk, encoding))
-        : stream.end()
+        ? stream.end(new Buffer(chunk, encoding), cb)
+        : stream.end(null, cb)
     }
 
     res.on = function on (type, listener) {

From c4ba4af8b2b3d51ef7fa749840f06c0369144568 Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Mon, 23 May 2016 15:12:07 -0600
Subject: [PATCH 03/20] Adding tests.

---
 test/compression.js | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/test/compression.js b/test/compression.js
index 81c00149..f37dce4b 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -676,6 +676,35 @@ describe('compression()', function () {
       .end()
     })
   })
+
+  describe('when callbacks are used', function () {
+    it('should call the passed callbacks', function(done){
+      var callbacks = 0;
+      var server = createServer({ threshold: '1kb' }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.write('Hello', null, function(){
+          callbacks++
+          res.flush()
+        });
+        res.write(' World', null, function(){
+          callbacks++
+          res.flush()
+        });
+        res.end(null, null, function(){
+          callbacks++
+        });
+      })
+
+      request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip')
+      .expect('Content-Encoding', 'gzip')
+      .end(function(){
+        assert.equal(callbacks, 3)
+        done();
+      });
+    })
+  })
 })
 
 function createServer (opts, fn) {

From bd60b964aca5d9d96253aaf2ff0df7d05f93f38a Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Mon, 23 May 2016 15:15:44 -0600
Subject: [PATCH 04/20] Updating docs.

---
 README.md | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index a5d599db..ccb0032a 100644
--- a/README.md
+++ b/README.md
@@ -205,10 +205,10 @@ app.get('/events', function (req, res) {
 
   // send a ping approx every 2 seconds
   var timer = setInterval(function () {
-    res.write('data: ping\n\n')
-
-    // !!! this is the important part
-    res.flush()
+    res.write('data: ping\n\n', function(){
+      // !!! this is the important part
+      res.flush()
+    })
   }, 2000)
 
   res.on('close', function () {

From 5cd1fe283c4fcfe93153385f1d7dc7d5ce712415 Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Mon, 23 May 2016 15:25:56 -0600
Subject: [PATCH 05/20] no message

---
 index.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/index.js b/index.js
index 552f602a..9c3f0ca0 100644
--- a/index.js
+++ b/index.js
@@ -74,7 +74,7 @@ function compression (options) {
 
     // proxy
 
-    res.write = function write (chunk, encoding, cb){
+    res.write = function write (chunk, encoding, cb) {
       if (ended) {
         return false
       }
@@ -88,7 +88,7 @@ function compression (options) {
         : _write.call(this, chunk, encoding, cb)
     };
 
-    res.end = function end (chunk, encoding, cb){
+    res.end = function end (chunk, encoding, cb) {
       if (ended) {
         return false
       }

From 2b85837de0b8a54509b1356ab87c0beaa31fc228 Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Mon, 23 May 2016 15:26:42 -0600
Subject: [PATCH 06/20] no message

---
 index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/index.js b/index.js
index 9c3f0ca0..2ab7f7a0 100644
--- a/index.js
+++ b/index.js
@@ -86,7 +86,7 @@ function compression (options) {
       return stream
         ? stream.write(new Buffer(chunk, encoding), cb)
         : _write.call(this, chunk, encoding, cb)
-    };
+    }
 
     res.end = function end (chunk, encoding, cb) {
       if (ended) {

From 31792c184df0da6f43d93c4b33501f7a6aaf8c69 Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Mon, 23 May 2016 16:29:49 -0600
Subject: [PATCH 07/20] Testing with and without compression.

---
 test/compression.js | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/test/compression.js b/test/compression.js
index f37dce4b..98809761 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -678,17 +678,40 @@ describe('compression()', function () {
   })
 
   describe('when callbacks are used', function () {
-    it('should call the passed callbacks', function(done){
+    it('should call the passed callbacks while compressing', function(done){
       var callbacks = 0;
-      var server = createServer({ threshold: '1kb' }, function (req, res) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.write('Hello', null, function(){
+          callbacks++
+        });
+        res.write(' World', null, function(){
+          callbacks++
+        });
+        res.end(null, null, function(){
+          callbacks++
+        });
+      })
+
+      request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip')
+      .expect('Content-Encoding', 'gzip')
+      .end(function(){
+        assert.equal(callbacks, 3)
+        done();
+      });
+    })
+    
+    it('should call the passed callbacks while not compressing', function(done){
+      var callbacks = 0;
+      var server = createServer({ threshold: '10kb' }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
         res.write('Hello', null, function(){
           callbacks++
-          res.flush()
         });
         res.write(' World', null, function(){
           callbacks++
-          res.flush()
         });
         res.end(null, null, function(){
           callbacks++

From bda469c06073313ced4182bf6f9f7723ef50ef95 Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Mon, 23 May 2016 17:00:22 -0600
Subject: [PATCH 08/20] Reverting readme change and ensuring callbacks are
 called in the order they are coded.

---
 README.md           |  8 ++++----
 test/compression.js | 44 ++++++++++----------------------------------
 2 files changed, 14 insertions(+), 38 deletions(-)

diff --git a/README.md b/README.md
index ccb0032a..a5d599db 100644
--- a/README.md
+++ b/README.md
@@ -205,10 +205,10 @@ app.get('/events', function (req, res) {
 
   // send a ping approx every 2 seconds
   var timer = setInterval(function () {
-    res.write('data: ping\n\n', function(){
-      // !!! this is the important part
-      res.flush()
-    })
+    res.write('data: ping\n\n')
+
+    // !!! this is the important part
+    res.flush()
   }, 2000)
 
   res.on('close', function () {
diff --git a/test/compression.js b/test/compression.js
index 98809761..58566eb6 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -678,18 +678,18 @@ describe('compression()', function () {
   })
 
   describe('when callbacks are used', function () {
-    it('should call the passed callbacks while compressing', function(done){
-      var callbacks = 0;
+    it('should call the passed callbacks in the order passed', function(done){
+      var callbackOutput = [];
       var server = createServer({ threshold: 0 }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
-        res.write('Hello', null, function(){
-          callbacks++
+        res.write('Hello', null, function (err){
+          callbackOutput.push(0);
         });
-        res.write(' World', null, function(){
-          callbacks++
+        res.write(' World', null, function (err){
+          callbackOutput.push(1);
         });
-        res.end(null, null, function(){
-          callbacks++
+        res.end(null, null, function (err){
+          callbackOutput.push(2);
         });
       })
 
@@ -698,32 +698,8 @@ describe('compression()', function () {
       .set('Accept-Encoding', 'gzip')
       .expect('Content-Encoding', 'gzip')
       .end(function(){
-        assert.equal(callbacks, 3)
-        done();
-      });
-    })
-    
-    it('should call the passed callbacks while not compressing', function(done){
-      var callbacks = 0;
-      var server = createServer({ threshold: '10kb' }, function (req, res) {
-        res.setHeader('Content-Type', 'text/plain')
-        res.write('Hello', null, function(){
-          callbacks++
-        });
-        res.write(' World', null, function(){
-          callbacks++
-        });
-        res.end(null, null, function(){
-          callbacks++
-        });
-      })
-
-      request(server)
-      .get('/')
-      .set('Accept-Encoding', 'gzip')
-      .expect('Content-Encoding', 'gzip')
-      .end(function(){
-        assert.equal(callbacks, 3)
+        assert.equal(callbackOutput.length, 3)
+        assert.deepEqual(callbackOutput, [0, 1, 2])
         done();
       });
     })

From 5f122e82e1f7ad0306023ee58f361bb9ad8ed910 Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Mon, 23 May 2016 17:08:58 -0600
Subject: [PATCH 09/20] Adding error handling.

---
 test/compression.js | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/test/compression.js b/test/compression.js
index 58566eb6..ffbfb66f 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -682,13 +682,13 @@ describe('compression()', function () {
       var callbackOutput = [];
       var server = createServer({ threshold: 0 }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
-        res.write('Hello', null, function (err){
+        res.write('Hello', null, function () {
           callbackOutput.push(0);
         });
-        res.write(' World', null, function (err){
+        res.write(' World', null, function () {
           callbackOutput.push(1);
         });
-        res.end(null, null, function (err){
+        res.end(null, null, function () {
           callbackOutput.push(2);
         });
       })
@@ -697,7 +697,10 @@ describe('compression()', function () {
       .get('/')
       .set('Accept-Encoding', 'gzip')
       .expect('Content-Encoding', 'gzip')
-      .end(function(){
+      .end(function (err) {
+        if (err) {
+          throw new Error(err);
+        }
         assert.equal(callbackOutput.length, 3)
         assert.deepEqual(callbackOutput, [0, 1, 2])
         done();

From eb1bad8768bd39ba6499254703028be8b6311c87 Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Mon, 23 May 2016 17:13:33 -0600
Subject: [PATCH 10/20] Fixing lint errors.

---
 test/compression.js | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/test/compression.js b/test/compression.js
index ffbfb66f..a2b52ef6 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -678,19 +678,19 @@ describe('compression()', function () {
   })
 
   describe('when callbacks are used', function () {
-    it('should call the passed callbacks in the order passed', function(done){
-      var callbackOutput = [];
+    it('should call the passed callbacks in the order passed', function (done) {
+      var callbackOutput = []
       var server = createServer({ threshold: 0 }, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
         res.write('Hello', null, function () {
-          callbackOutput.push(0);
-        });
+          callbackOutput.push(0)
+        })
         res.write(' World', null, function () {
-          callbackOutput.push(1);
-        });
+          callbackOutput.push(1)
+        })
         res.end(null, null, function () {
-          callbackOutput.push(2);
-        });
+          callbackOutput.push(2)
+        })
       })
 
       request(server)
@@ -699,12 +699,12 @@ describe('compression()', function () {
       .expect('Content-Encoding', 'gzip')
       .end(function (err) {
         if (err) {
-          throw new Error(err);
+          throw new Error(err)
         }
         assert.equal(callbackOutput.length, 3)
         assert.deepEqual(callbackOutput, [0, 1, 2])
-        done();
-      });
+        done()
+      })
     })
   })
 })

From ac8914b1589d2c6c91417e870bdbeec3a3fb5c1b Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Mon, 23 May 2016 23:24:02 -0600
Subject: [PATCH 11/20] Adding test with no streaming.

---
 test/compression.js | 37 +++++++++++++++++++++++++++++++++++--
 1 file changed, 35 insertions(+), 2 deletions(-)

diff --git a/test/compression.js b/test/compression.js
index a2b52ef6..04106cdf 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -678,9 +678,9 @@ describe('compression()', function () {
   })
 
   describe('when callbacks are used', function () {
-    it('should call the passed callbacks in the order passed', function (done) {
+    it('should call the passed callbacks in the order passed when compressing', function (done) {
       var callbackOutput = []
-      var server = createServer({ threshold: 0 }, function (req, res) {
+      var server = createServer(null, function (req, res) {
         res.setHeader('Content-Type', 'text/plain')
         res.write('Hello', null, function () {
           callbackOutput.push(0)
@@ -707,6 +707,39 @@ describe('compression()', function () {
       })
     })
   })
+
+  describe('when callbacks are used', function () {
+    it('should call the passed callbacks in the order passed when not compressing', function (done) {
+      var callbackOutput = []
+      var server = createServer(null, function (req, res) {
+        res.setHeader('Cache-Control', 'no-transform')
+        res.setHeader('Content-Type', 'text/plain')
+        res.write('hello,', null, function () {
+          callbackOutput.push(0)
+        })
+        res.write(' world', null, function () {
+          callbackOutput.push(1)
+        })
+        res.end(null, null, function () {
+          callbackOutput.push(2)
+        })
+      })
+
+      request(server)
+      .get('/')
+      .set('Accept-Encoding', 'gzip')
+      .expect('Cache-Control', 'no-transform')
+      .expect(shouldNotHaveHeader('Content-Encoding'))
+      .end(function (err) {
+        if (err) {
+          throw new Error(err)
+        }
+        assert.equal(callbackOutput.length, 3)
+        assert.deepEqual(callbackOutput, [0, 1, 2])
+        done()
+      })
+    })
+  })
 })
 
 function createServer (opts, fn) {

From 866775db3d4fb31d3582dae5dfeff78542d7408a Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Mon, 23 May 2016 23:30:06 -0600
Subject: [PATCH 12/20] no message

---
 test/compression.js | 2 --
 1 file changed, 2 deletions(-)

diff --git a/test/compression.js b/test/compression.js
index 04106cdf..181de7ef 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -706,9 +706,7 @@ describe('compression()', function () {
         done()
       })
     })
-  })
 
-  describe('when callbacks are used', function () {
     it('should call the passed callbacks in the order passed when not compressing', function (done) {
       var callbackOutput = []
       var server = createServer(null, function (req, res) {

From c1f3aab8b4c095451b7d2296d715f79ed44469ec Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Tue, 24 May 2016 00:18:17 -0600
Subject: [PATCH 13/20] Attempting to handle pre-11 node versions.

---
 index.js | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/index.js b/index.js
index 2ab7f7a0..eeb8a13e 100644
--- a/index.js
+++ b/index.js
@@ -60,6 +60,7 @@ function compression (options) {
     var length
     var listeners = []
     var stream
+    var noop = function () {}
 
     var _end = res.end
     var _on = res.on
@@ -79,6 +80,8 @@ function compression (options) {
         return false
       }
 
+      cb = (res.write.length === 3) ? cb : noop
+
       if (!this._header) {
         this._implicitHeader()
       }
@@ -93,6 +96,8 @@ function compression (options) {
         return false
       }
 
+      cb = (res.end.length === 3) ? cb : noop
+
       if (!this._header) {
         // estimate the length
         if (!this.getHeader('Content-Length')) {

From b0055d2c7a8cf1c242786b440f88703a35a2bb75 Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Tue, 24 May 2016 00:25:26 -0600
Subject: [PATCH 14/20] no message

---
 test/compression.js | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/test/compression.js b/test/compression.js
index 181de7ef..172abe69 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -679,8 +679,10 @@ describe('compression()', function () {
 
   describe('when callbacks are used', function () {
     it('should call the passed callbacks in the order passed when compressing', function (done) {
+      var hasCallbacks = false
       var callbackOutput = []
       var server = createServer(null, function (req, res) {
+        hasCallbacks = (res.write.length === 3 && res.end.length === 3)
         res.setHeader('Content-Type', 'text/plain')
         res.write('Hello', null, function () {
           callbackOutput.push(0)
@@ -701,15 +703,19 @@ describe('compression()', function () {
         if (err) {
           throw new Error(err)
         }
-        assert.equal(callbackOutput.length, 3)
-        assert.deepEqual(callbackOutput, [0, 1, 2])
+        if (hasCallbacks) {
+          assert.equal(callbackOutput.length, 3)
+          assert.deepEqual(callbackOutput, [0, 1, 2])
+        }
         done()
       })
     })
 
     it('should call the passed callbacks in the order passed when not compressing', function (done) {
+      var hasCallbacks = false
       var callbackOutput = []
       var server = createServer(null, function (req, res) {
+        hasCallbacks = (res.write.length === 3 && res.end.length === 3)
         res.setHeader('Cache-Control', 'no-transform')
         res.setHeader('Content-Type', 'text/plain')
         res.write('hello,', null, function () {
@@ -732,8 +738,10 @@ describe('compression()', function () {
         if (err) {
           throw new Error(err)
         }
-        assert.equal(callbackOutput.length, 3)
-        assert.deepEqual(callbackOutput, [0, 1, 2])
+        if (hasCallbacks) {
+          assert.equal(callbackOutput.length, 3)
+          assert.deepEqual(callbackOutput, [0, 1, 2])
+        }
         done()
       })
     })

From 3ab2f0d7b3275dd1b41826dc6b6be34e2afc74d8 Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Tue, 24 May 2016 01:15:14 -0600
Subject: [PATCH 15/20] Handling node 0.8 and 0.10.

---
 index.js            | 20 ++++++++++----------
 test/compression.js |  4 ++--
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/index.js b/index.js
index eeb8a13e..0439f691 100644
--- a/index.js
+++ b/index.js
@@ -62,9 +62,9 @@ function compression (options) {
     var stream
     var noop = function () {}
 
-    var _end = res.end
+    res._end = res.end
+    res._write = res.write
     var _on = res.on
-    var _write = res.write
 
     // flush
     res.flush = function flush () {
@@ -80,7 +80,7 @@ function compression (options) {
         return false
       }
 
-      cb = (res.write.length === 3) ? cb : noop
+      cb = (res._end.length === 3) ? cb : null
 
       if (!this._header) {
         this._implicitHeader()
@@ -88,7 +88,7 @@ function compression (options) {
 
       return stream
         ? stream.write(new Buffer(chunk, encoding), cb)
-        : _write.call(this, chunk, encoding, cb)
+        : res._write.call(this, chunk, encoding, cb)
     }
 
     res.end = function end (chunk, encoding, cb) {
@@ -96,7 +96,7 @@ function compression (options) {
         return false
       }
 
-      cb = (res.end.length === 3) ? cb : noop
+      cb = (res._end.length === 3) ? cb : null
 
       if (!this._header) {
         // estimate the length
@@ -108,7 +108,7 @@ function compression (options) {
       }
 
       if (!stream) {
-        return _end.call(this, chunk, encoding, cb)
+        return res._end.call(this, chunk, encoding, cb)
       }
 
       // mark ended
@@ -116,8 +116,8 @@ function compression (options) {
 
       // write Buffer for Node.js 0.8
       return chunk
-        ? stream.end(new Buffer(chunk, encoding), cb)
-        : stream.end(null, cb)
+        ? stream.end(new Buffer(chunk, encoding), null, cb)
+        : stream.end(null, null, cb)
     }
 
     res.on = function on (type, listener) {
@@ -207,13 +207,13 @@ function compression (options) {
 
       // compression
       stream.on('data', function onStreamData (chunk) {
-        if (_write.call(res, chunk) === false) {
+        if (res._write.call(res, chunk) === false) {
           stream.pause()
         }
       })
 
       stream.on('end', function onStreamEnd () {
-        _end.call(res)
+        res._end.call(res)
       })
 
       _on.call(res, 'drain', function onResponseDrain () {
diff --git a/test/compression.js b/test/compression.js
index 172abe69..20251911 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -682,7 +682,7 @@ describe('compression()', function () {
       var hasCallbacks = false
       var callbackOutput = []
       var server = createServer(null, function (req, res) {
-        hasCallbacks = (res.write.length === 3 && res.end.length === 3)
+        hasCallbacks = (res._write.length === 3 && res._end.length === 3)
         res.setHeader('Content-Type', 'text/plain')
         res.write('Hello', null, function () {
           callbackOutput.push(0)
@@ -715,7 +715,7 @@ describe('compression()', function () {
       var hasCallbacks = false
       var callbackOutput = []
       var server = createServer(null, function (req, res) {
-        hasCallbacks = (res.write.length === 3 && res.end.length === 3)
+        hasCallbacks = (res._write.length === 3 && res._end.length === 3)
         res.setHeader('Cache-Control', 'no-transform')
         res.setHeader('Content-Type', 'text/plain')
         res.write('hello,', null, function () {

From 79c6b75b3a28aa7dacf0c3e555a8392a203f59d8 Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Tue, 24 May 2016 02:06:47 -0600
Subject: [PATCH 16/20] Typo.

---
 index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/index.js b/index.js
index 0439f691..dbab5d50 100644
--- a/index.js
+++ b/index.js
@@ -80,7 +80,7 @@ function compression (options) {
         return false
       }
 
-      cb = (res._end.length === 3) ? cb : null
+      cb = (res._write.length === 3) ? cb : null
 
       if (!this._header) {
         this._implicitHeader()

From 0f617c7f15a1826adf3d8782b282facd6cac4642 Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Tue, 24 May 2016 14:05:48 -0600
Subject: [PATCH 17/20] Checking OutgoingMessage.prototype.

---
 index.js            | 6 ++++--
 test/compression.js | 6 ++----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/index.js b/index.js
index dbab5d50..e6c494ce 100644
--- a/index.js
+++ b/index.js
@@ -21,6 +21,8 @@ var debug = require('debug')('compression')
 var onHeaders = require('on-headers')
 var vary = require('vary')
 var zlib = require('zlib')
+var OutgoingMessage = require('http').OutgoingMessage
+var hasCallback = (OutgoingMessage.prototype.write.length === 3)
 
 /**
  * Module exports.
@@ -80,7 +82,7 @@ function compression (options) {
         return false
       }
 
-      cb = (res._write.length === 3) ? cb : null
+      cb = hasCallback ? cb : null
 
       if (!this._header) {
         this._implicitHeader()
@@ -96,7 +98,7 @@ function compression (options) {
         return false
       }
 
-      cb = (res._end.length === 3) ? cb : null
+      cb = hasCallback ? cb : null
 
       if (!this._header) {
         // estimate the length
diff --git a/test/compression.js b/test/compression.js
index 20251911..06e31c66 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -3,6 +3,8 @@ var bytes = require('bytes')
 var crypto = require('crypto')
 var http = require('http')
 var request = require('supertest')
+var OutgoingMessage = http.OutgoingMessage
+var hasCallbacks = (OutgoingMessage.prototype.write.length === 3)
 
 var compression = require('..')
 
@@ -679,10 +681,8 @@ describe('compression()', function () {
 
   describe('when callbacks are used', function () {
     it('should call the passed callbacks in the order passed when compressing', function (done) {
-      var hasCallbacks = false
       var callbackOutput = []
       var server = createServer(null, function (req, res) {
-        hasCallbacks = (res._write.length === 3 && res._end.length === 3)
         res.setHeader('Content-Type', 'text/plain')
         res.write('Hello', null, function () {
           callbackOutput.push(0)
@@ -712,10 +712,8 @@ describe('compression()', function () {
     })
 
     it('should call the passed callbacks in the order passed when not compressing', function (done) {
-      var hasCallbacks = false
       var callbackOutput = []
       var server = createServer(null, function (req, res) {
-        hasCallbacks = (res._write.length === 3 && res._end.length === 3)
         res.setHeader('Cache-Control', 'no-transform')
         res.setHeader('Content-Type', 'text/plain')
         res.write('hello,', null, function () {

From 4b50f90e1413f1fc683a59fa353a030017d11708 Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Fri, 27 May 2016 20:19:42 -0600
Subject: [PATCH 18/20] Making res.flush synchronous.

---
 index.js            | 38 +++++++++++++-------------
 test/compression.js | 66 ---------------------------------------------
 2 files changed, 18 insertions(+), 86 deletions(-)

diff --git a/index.js b/index.js
index e6c494ce..07d30d08 100644
--- a/index.js
+++ b/index.js
@@ -21,8 +21,6 @@ var debug = require('debug')('compression')
 var onHeaders = require('on-headers')
 var vary = require('vary')
 var zlib = require('zlib')
-var OutgoingMessage = require('http').OutgoingMessage
-var hasCallback = (OutgoingMessage.prototype.write.length === 3)
 
 /**
  * Module exports.
@@ -62,44 +60,44 @@ function compression (options) {
     var length
     var listeners = []
     var stream
-    var noop = function () {}
 
-    res._end = res.end
-    res._write = res.write
+    var _end = res.end
     var _on = res.on
+    var _write = res.write
+
+    var flushCB = function flushCB () {
+      stream.flush()
+    }
 
     // flush
     res.flush = function flush () {
       if (stream) {
-        stream.flush()
+        // call write and pass flushCB to force synchronous behavior
+        stream.write('', flushCB)
       }
     }
 
     // proxy
 
-    res.write = function write (chunk, encoding, cb) {
+    res.write = function write (chunk, encoding) {
       if (ended) {
         return false
       }
 
-      cb = hasCallback ? cb : null
-
       if (!this._header) {
         this._implicitHeader()
       }
 
       return stream
-        ? stream.write(new Buffer(chunk, encoding), cb)
-        : res._write.call(this, chunk, encoding, cb)
+        ? stream.write(new Buffer(chunk, encoding))
+        : _write.call(this, chunk, encoding)
     }
 
-    res.end = function end (chunk, encoding, cb) {
+    res.end = function end (chunk, encoding) {
       if (ended) {
         return false
       }
 
-      cb = hasCallback ? cb : null
-
       if (!this._header) {
         // estimate the length
         if (!this.getHeader('Content-Length')) {
@@ -110,7 +108,7 @@ function compression (options) {
       }
 
       if (!stream) {
-        return res._end.call(this, chunk, encoding, cb)
+        return _end.call(this, chunk, encoding)
       }
 
       // mark ended
@@ -118,8 +116,8 @@ function compression (options) {
 
       // write Buffer for Node.js 0.8
       return chunk
-        ? stream.end(new Buffer(chunk, encoding), null, cb)
-        : stream.end(null, null, cb)
+        ? stream.end(new Buffer(chunk, encoding))
+        : stream.end()
     }
 
     res.on = function on (type, listener) {
@@ -209,13 +207,13 @@ function compression (options) {
 
       // compression
       stream.on('data', function onStreamData (chunk) {
-        if (res._write.call(res, chunk) === false) {
+        if (_write.call(res, chunk) === false) {
           stream.pause()
         }
       })
 
       stream.on('end', function onStreamEnd () {
-        res._end.call(res)
+        _end.call(res)
       })
 
       _on.call(res, 'drain', function onResponseDrain () {
@@ -280,4 +278,4 @@ function shouldTransform (req, res) {
   // https://tools.ietf.org/html/rfc7234#section-5.2.2.4
   return !cacheControl ||
     !cacheControlNoTransformRegExp.test(cacheControl)
-}
+}
\ No newline at end of file
diff --git a/test/compression.js b/test/compression.js
index 06e31c66..a49006f8 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -678,72 +678,6 @@ describe('compression()', function () {
       .end()
     })
   })
-
-  describe('when callbacks are used', function () {
-    it('should call the passed callbacks in the order passed when compressing', function (done) {
-      var callbackOutput = []
-      var server = createServer(null, function (req, res) {
-        res.setHeader('Content-Type', 'text/plain')
-        res.write('Hello', null, function () {
-          callbackOutput.push(0)
-        })
-        res.write(' World', null, function () {
-          callbackOutput.push(1)
-        })
-        res.end(null, null, function () {
-          callbackOutput.push(2)
-        })
-      })
-
-      request(server)
-      .get('/')
-      .set('Accept-Encoding', 'gzip')
-      .expect('Content-Encoding', 'gzip')
-      .end(function (err) {
-        if (err) {
-          throw new Error(err)
-        }
-        if (hasCallbacks) {
-          assert.equal(callbackOutput.length, 3)
-          assert.deepEqual(callbackOutput, [0, 1, 2])
-        }
-        done()
-      })
-    })
-
-    it('should call the passed callbacks in the order passed when not compressing', function (done) {
-      var callbackOutput = []
-      var server = createServer(null, function (req, res) {
-        res.setHeader('Cache-Control', 'no-transform')
-        res.setHeader('Content-Type', 'text/plain')
-        res.write('hello,', null, function () {
-          callbackOutput.push(0)
-        })
-        res.write(' world', null, function () {
-          callbackOutput.push(1)
-        })
-        res.end(null, null, function () {
-          callbackOutput.push(2)
-        })
-      })
-
-      request(server)
-      .get('/')
-      .set('Accept-Encoding', 'gzip')
-      .expect('Cache-Control', 'no-transform')
-      .expect(shouldNotHaveHeader('Content-Encoding'))
-      .end(function (err) {
-        if (err) {
-          throw new Error(err)
-        }
-        if (hasCallbacks) {
-          assert.equal(callbackOutput.length, 3)
-          assert.deepEqual(callbackOutput, [0, 1, 2])
-        }
-        done()
-      })
-    })
-  })
 })
 
 function createServer (opts, fn) {

From 2e995d03c0f4b12c6de3a0453f68bba611f75a7c Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Fri, 27 May 2016 20:20:32 -0600
Subject: [PATCH 19/20] no message

---
 test/compression.js | 2 --
 1 file changed, 2 deletions(-)

diff --git a/test/compression.js b/test/compression.js
index a49006f8..81c00149 100644
--- a/test/compression.js
+++ b/test/compression.js
@@ -3,8 +3,6 @@ var bytes = require('bytes')
 var crypto = require('crypto')
 var http = require('http')
 var request = require('supertest')
-var OutgoingMessage = http.OutgoingMessage
-var hasCallbacks = (OutgoingMessage.prototype.write.length === 3)
 
 var compression = require('..')
 

From 74fdf7bd2dbb508c4ef15cd3b63dd4049e05a0ab Mon Sep 17 00:00:00 2001
From: Joseph Podwys <joseph@podwys.com>
Date: Fri, 27 May 2016 20:21:07 -0600
Subject: [PATCH 20/20] no message

---
 index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/index.js b/index.js
index 07d30d08..5d9b0df5 100644
--- a/index.js
+++ b/index.js
@@ -278,4 +278,4 @@ function shouldTransform (req, res) {
   // https://tools.ietf.org/html/rfc7234#section-5.2.2.4
   return !cacheControl ||
     !cacheControlNoTransformRegExp.test(cacheControl)
-}
\ No newline at end of file
+}