stream: Handle multi-corking properly

This adds proper support for the following situation:

    w.cork();
    w.write(...);
    w.cork();
    w.write(...);
    w.uncork();
    w.write(...);
    w.uncork();

This is relevant when you have a function (as we do in HTTP) that wants
to use cork, but in some cases, want to have a cork/uncork *around*
that function, without losing the benefits of writev.

lib/_stream_writable.js

@@ -77,7 +77,7 @@ function WritableState(options, stream) {
   this.writing = false;
 
   // when true all writes will be buffered until .uncork() call
-  this.corked = false;
+  this.corked = 0;
 
   // a flag to be able to tell if the onwrite cb is called immediately,
   // or on a later tick.  We set this to true at first, becuase any
@@ -190,16 +190,17 @@ Writable.prototype.write = function(chunk, encoding, cb) {
 Writable.prototype.cork = function() {
   var state = this._writableState;
 
-  state.corked = true;
+  state.corked++;
 };
 
 Writable.prototype.uncork = function() {
   var state = this._writableState;
 
   if (state.corked) {
-    state.corked = false;
+    state.corked--;
 
     if (!state.writing &&
+        !state.corked &&
         !state.finished &&
         !state.bufferProcessing &&
         state.buffer.length)
@@ -221,6 +222,8 @@ function decodeChunk(state, chunk, encoding) {
 // If we return false, then we need a drain event, so set that flag.
 function writeOrBuffer(stream, state, chunk, encoding, cb) {
   chunk = decodeChunk(state, chunk, encoding);
+  if (Buffer.isBuffer(chunk))
+    encoding = 'buffer';
   var len = state.objectMode ? 1 : chunk.length;
 
   state.length += len;
@@ -392,8 +395,11 @@ Writable.prototype.end = function(chunk, encoding, cb) {
   if (typeof chunk !== 'undefined' && chunk !== null)
     this.write(chunk, encoding);
 
-  // .end() should .uncork()
+  // .end() fully uncorks
+  if (state.corked) {
+    state.corked = 1;
     this.uncork();
+  }
 
   // ignore unnecessary end() calls.
   if (!state.ending && !state.finished)

test/simple/test-stream-writev.js

@@ -0,0 +1,121 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+
+var stream = require('stream');
+
+var queue = [];
+for (var decode = 0; decode < 2; decode++) {
+  for (var uncork = 0; uncork < 2; uncork++) {
+    for (var multi = 0; multi < 2; multi++) {
+      queue.push([!!decode, !!uncork, !!multi]);
+    }
+  }
+}
+
+run();
+
+function run() {
+  var t = queue.pop();
+  if (t)
+    test(t[0], t[1], t[2], run);
+  else
+    console.log('ok');
+}
+
+function test(decode, uncork, multi, next) {
+  console.log('# decode=%j uncork=%j multi=%j', decode, uncork, multi);
+  var counter = 0;
+  var expectCount = 0;
+  function cnt(msg) {
+    expectCount++;
+    var expect = expectCount;
+    var called = false;
+    return function(er) {
+      if (er)
+        throw er;
+      called = true;
+      counter++;
+      assert.equal(counter, expect);
+    };
+  }
+
+  var w = new stream.Writable({ decodeStrings: decode });
+  w._write = function(chunk, e, cb) {
+    assert(false, 'Should not call _write');
+  };
+
+  var expectChunks = decode ?
+      [{ encoding: 'buffer',
+         chunk: [104, 101, 108, 108, 111, 44, 32] },
+       { encoding: 'buffer', chunk: [119, 111, 114, 108, 100] },
+       { encoding: 'buffer', chunk: [33] },
+       { encoding: 'buffer',
+         chunk: [10, 97, 110, 100, 32, 116, 104, 101, 110, 46, 46, 46] },
+       { encoding: 'buffer',
+         chunk: [250, 206, 190, 167, 222, 173, 190, 239, 222, 202, 251, 173] }] :
+      [{ encoding: 'ascii', chunk: 'hello, ' },
+       { encoding: 'utf8', chunk: 'world' },
+       { encoding: 'buffer', chunk: [33] },
+       { encoding: 'binary', chunk: '\nand then...' },
+       { encoding: 'hex', chunk: 'facebea7deadbeefdecafbad' }];
+
+  var actualChunks;
+  w._writev = function(chunks, cb) {
+    actualChunks = chunks.map(function(chunk) {
+      return {
+        encoding: chunk.encoding,
+        chunk: Buffer.isBuffer(chunk.chunk) ?
+            Array.prototype.slice.call(chunk.chunk) : chunk.chunk
+      };
+    });
+    cb();
+  };
+
+  w.cork();
+  w.write('hello, ', 'ascii', cnt('hello'));
+  w.write('world', 'utf8', cnt('world'));
+
+  if (multi)
+    w.cork();
+
+  w.write(new Buffer('!'), 'buffer', cnt('!'));
+  w.write('\nand then...', 'binary', cnt('and then'));
+
+  if (multi)
+    w.uncork();
+
+  w.write('facebea7deadbeefdecafbad', 'hex', cnt('hex'));
+
+  if (uncork)
+    w.uncork();
+
+  w.end(cnt('end'));
+
+  w.on('finish', function() {
+    // make sure finish comes after all the write cb
+    cnt('finish')();
+    assert.deepEqual(expectChunks, actualChunks);
+    next();
+  });
+}