Fix: Use custom implementation of fs.WriteStream that supports flush (fixes #189)

Author: phated

lib/dest/write-contents/write-stream.js

@@ -1,65 +1,58 @@
 'use strict';
 
-var fs = require('graceful-fs');
-
 var fo = require('../../file-operations');
 var readStream = require('../../src/get-contents/read-stream');
 
 function writeStream(file, onWritten) {
   var opt = {
     mode: file.stat.mode,
+    // TODO: need to test this (node calls this `flags` property)
     flag: file.flag,
   };
 
-  var outStream = fs.createWriteStream(file.path, opt);
-  var fd = null;
-
-  file.contents.once('error', complete);
-  file.contents.once('end', readStreamEnd);
-  outStream.once('error', complete);
-  outStream.once('finish', complete);
-  outStream.once('open', onOpen);
+  // TODO: is this the best API?
+  var outStream = fo.createWriteStream(file.path, opt, onFlush);
 
-  // Streams are piped with end disabled, this prevents the
-  // WriteStream from closing the file descriptor after all
-  // data is written.
-  file.contents.pipe(outStream, { end: false });
+  file.contents.once('error', onComplete);
+  outStream.once('error', onComplete);
+  outStream.once('finish', onComplete);
 
-  // Obtain the file descriptor from the "open" event.
-  function onOpen(openFd) {
-    fd = openFd;
-  }
+  // TODO: should this use a clone?
+  file.contents.pipe(outStream);
 
-  function readStreamEnd() {
-    readStream(file, complete);
-  }
+  function onComplete(streamErr) {
+    // Cleanup event handlers before closing
+    file.contents.removeListener('error', onComplete);
+    outStream.removeListener('error', onComplete);
+    outStream.removeListener('finish', onComplete);
 
-  function end(propagatedErr) {
-    outStream.end(onEnd);
+    // Need to guarantee the fd is closed before forwarding the error
+    outStream.once('close', onClose);
+    outStream.end();
 
-    function onEnd(endErr) {
-      onWritten(propagatedErr || endErr);
+    function onClose(closeErr) {
+      onWritten(streamErr || closeErr);
     }
   }
 
   // Cleanup
-  function complete(streamErr) {
-    file.contents.removeListener('error', complete);
-    file.contents.removeListener('end', readStreamEnd);
-    outStream.removeListener('error', complete);
-    outStream.removeListener('finish', complete);
-    outStream.removeListener('open', onOpen);
+  function onFlush(fd, callback) {
+    // TODO: removing this before readStream because it replaces the stream
+    file.contents.removeListener('error', onComplete);
 
-    if (streamErr) {
-      return end(streamErr);
-    }
+    // TODO: this is doing sync stuff & the callback seems unnecessary
+    // TODO: do we really want to replace the contents stream or should we use a clone
+    readStream(file, complete);
 
-    if (typeof fd !== 'number') {
-      return end();
-    }
+    function complete() {
+      if (typeof fd !== 'number') {
+        return callback();
+      }
 
-    fo.updateMetadata(fd, file, end);
+      fo.updateMetadata(fd, file, callback);
+    }
   }
+
 }
 
 module.exports = writeStream;

lib/file-operations.js

@@ -1,10 +1,13 @@
 'use strict';
 
+var util = require('util');
+
 var fs = require('graceful-fs');
 var path = require('path');
 var assign = require('object-assign');
 var isEqual = require('lodash.isequal');
 var isValidDate = require('vali-date');
+var FlushWriteStream = require('flush-write-stream');
 
 var constants = require('./constants');
 
@@ -324,6 +327,103 @@ function mkdirp(dirpath, customMode, callback) {
   }
 }
 
+function createWriteStream(path, options, flush) {
+  return new WriteStream(path, options, flush);
+}
+
+// Taken from node core and altered to receive a flush function and simplified
+// To be used for cleanup (like updating times/mode/etc)
+function WriteStream(path, options, flush) {
+  // Not exposed so we can avoid the case where someone doesn't use `new`
+
+  if (typeof options === 'function') {
+    flush = options;
+    options = null;
+  }
+
+  options = options || {};
+
+  FlushWriteStream.call(this, options, worker, cleanup);
+
+  this.flush = flush;
+  this.path = path;
+
+  this.mode = options.mode || constants.DEFAULT_FILE_MODE;
+  this.flag = options.flag || 'w';
+  this.pos = APPEND_MODE_REGEXP.test(this.flag) ? null : 0;;
+
+  // Used by node's `fs.WriteStream`
+  this.fd = null;
+  this.start = null;
+
+  this.open();
+
+  // Dispose on finish.
+  this.once('finish', this.close);
+}
+
+util.inherits(WriteStream, FlushWriteStream);
+
+WriteStream.prototype.open = function() {
+  var self = this;
+
+  fs.open(this.path, this.flag, this.mode, onOpen);
+
+  function onOpen(openErr, fd) {
+    if (openErr) {
+      self.destroy();
+      self.emit('error', openErr);
+      return;
+    }
+
+    self.fd = fd;
+    self.emit('open', fd);
+  }
+};
+
+// Use our `end` method since it is patched for flush
+WriteStream.prototype.destroySoon = WriteStream.prototype.end;
+// Use node's `fs.WriteStream` methods
+WriteStream.prototype.destroy = fs.WriteStream.prototype.destroy;
+WriteStream.prototype.close = fs.WriteStream.prototype.close;
+
+function worker(data, encoding, callback) {
+  var self = this;
+
+  // This is from node core but I have no idea how to get code coverage on it
+  if (!Buffer.isBuffer(data)) {
+    return this.emit('error', new Error('Invalid data'));
+  }
+
+  if (typeof this.fd !== 'number') {
+    return this.once('open', onOpen);
+  }
+
+  fs.write(this.fd, data, 0, data.length, this.pos, onWrite);
+
+  function onOpen() {
+    self._write(data, encoding, callback);
+  }
+
+  function onWrite(writeErr) {
+    if (writeErr) {
+      self.destroy();
+      callback(writeErr);
+      return;
+    }
+
+    callback();
+  }
+}
+
+function cleanup(callback) {
+  if (typeof this.flush !== 'function') {
+    return callback();
+  }
+
+  this.flush(this.fd, callback);
+}
+
 module.exports = {
   closeFd: closeFd,
   isValidUnixId: isValidUnixId,
@@ -334,4 +434,5 @@ module.exports = {
   updateMetadata: updateMetadata,
   writeFile: writeFile,
   mkdirp: mkdirp,
+  createWriteStream: createWriteStream,
 };

package.json

@@ -12,6 +12,7 @@
   ],
   "dependencies": {
     "duplexify": "^3.2.0",
+    "flush-write-stream": "^1.0.0",
     "glob-stream": "^5.3.2",
     "graceful-fs": "^4.0.0",
     "gulp-sourcemaps": "1.6.0",
@@ -36,6 +37,7 @@
     "eslint": "^1.10.3",
     "eslint-config-gulp": "^2.0.0",
     "expect": "^1.14.0",
+    "from2": "^2.1.1",
     "github-changes": "^1.0.1",
     "istanbul": "^0.3.0",
     "istanbul-coveralls": "^1.0.1",

test/dest.js

@@ -18,6 +18,7 @@ var expect = require('expect');
 var bufEqual = require('buffer-equal');
 var through = require('through2');
 var File = require('vinyl');
+var from = require('from2');
 
 var should = require('should');
 require('mocha');
@@ -1146,7 +1147,9 @@ describe('dest stream', function() {
     var inputPath = path.join(__dirname, './fixtures/test.coffee');
     var inputBase = path.join(__dirname, './fixtures/');
 
-    var contentStream = through.obj();
+    var contentStream = from(function(size, cb) {
+      cb(new Error('mocked error'));
+    });
     var expectedFile = new File({
       base: inputBase,
       cwd: __dirname,
@@ -1156,9 +1159,6 @@ describe('dest stream', function() {
 
     var stream = vfs.dest('./out-fixtures/', { cwd: __dirname });
     stream.write(expectedFile);
-    setTimeout(function() {
-      contentStream.emit('error', new Error('mocked error'));
-    }, 100);
     stream.on('error', function(err) {
       expect(err).toExist();
       done();