"Fix" repl race condition

Makefile

@@ -387,7 +387,7 @@ bench-idle:
 	./$(NODE_EXE) benchmark/idle_clients.js &
 
 jslint:
-	./$(NODE_EXE) tools/eslint/bin/eslint.js src/*.js lib/*.js --reset --quiet
+	./$(NODE_EXE) tools/eslint/bin/eslint.js src/*.js lib/*.js lib/internal/*.js --reset --quiet
 
 CPPLINT_EXCLUDE ?=
 CPPLINT_EXCLUDE += src/node_lttng.cc

lib/internal/repl.js

@@ -3,6 +3,9 @@
 const Interface = require('readline').Interface;
 const REPL = require('repl');
 const path = require('path');
+const util = require('util');
+
+const debug = util.debuglog('repl');
 
 module.exports = Object.create(REPL);
 module.exports.createInternalRepl = createRepl;
@@ -17,16 +20,18 @@ function replStart() {
  return REPL.start.apply(REPL, arguments);
 }
 
-function createRepl(env, cb) {
+function createRepl(env, attemptPersistentHistory, cb) {
  const opts = {
  ignoreUndefined: false,
- terminal: process.stdout.isTTY,
  useGlobal: true
  };
 
  if (parseInt(env.NODE_NO_READLINE)) {
  opts.terminal = false;
  }
+ if (parseInt(env.NODE_FORCE_READLINE)) {
+ opts.terminal = true;
+ }
  if (parseInt(env.NODE_DISABLE_COLORS)) {
  opts.useColors = false;
  }
@@ -51,8 +56,13 @@ function createRepl(env, cb) {
  }
 
  const repl = REPL.start(opts);
- if (opts.terminal && env.NODE_REPL_HISTORY_FILE) {
- return setupHistory(repl, env.NODE_REPL_HISTORY_FILE, cb);
+ if (env.NODE_REPL_HISTORY_FILE && attemptPersistentHistory) {
+ return setupHistory(repl, env.NODE_REPL_HISTORY_FILE, function(err) {
+ if (err) {
+ repl.close();
+ }
+ cb(err, repl);
+ });
  }
  repl._historyPrev = _replHistoryMessage;
  cb(null, repl);
@@ -64,27 +74,14 @@ function setupHistory(repl, historyPath, ready) {
  var writing = false;
  var pending = false;
  repl.pause();
- fs.open(historyPath, 'a+', oninit);
-
- function oninit(err, hnd) {
- if (err) {
- return ready(err);
- }
- fs.close(hnd, onclose);
- }
-
- function onclose(err) {
- if (err) {
- return ready(err);
- }
- fs.readFile(historyPath, 'utf8', onread);
- }
+ fs.readFile(historyPath, {encoding: 'utf8', flag: 'a+'}, ondata);
 
- function onread(err, data) {
+ function ondata(err, data) {
  if (err) {
  return ready(err);
  }
 
+ debug('loaded %s', historyPath);
  if (data) {
  try {
  repl.history = JSON.parse(data);
@@ -98,17 +95,16 @@ function setupHistory(repl, historyPath, ready) {
  }
  }
 
-fs.open(historyPath, 'w', onhandle);
+getTempFile(ontmpfile);
  }
 
- function onhandle(err, hnd) {
+ function ontmpfile(err, tmpinfo) {
  if (err) {
  return ready(err);
  }
- repl._historyHandle = hnd;
+ repl._historyTempInfo = tmpinfo;
  repl.on('line', online);
-
- // reading the file data out erases it
+ repl.on('exit', removeTempFile);
  repl.once('flushHistory', function() {
  repl.resume();
  ready(null, repl);
@@ -134,11 +130,11 @@ function setupHistory(repl, historyPath, ready) {
  return;
  }
  writing = true;
- const historyData = JSON.stringify(repl.history, null, 2);
-fs.write(repl._historyHandle, historyData, 0, 'utf8', onwritten);
+ const historyData = JSON.stringify(repl.history || [], null, 2);
+writeAndSwapTemp(historyData, repl._historyTempInfo, historyPath, onflushed);
  }
 
- function onwritten(err, data) {
+ function onflushed(err, data) {
  writing = false;
  if (pending) {
  pending = false;
@@ -150,6 +146,17 @@ function setupHistory(repl, historyPath, ready) {
  }
  }
  }
+
+ function removeTempFile() {
+ if (repl._flushing)
+ return repl.once('flushHistory', function() {
+ removeTempFile();
+ });
+ repl._flushing = true;
+ fs.unlink(repl._historyTempInfo.path, function() {
+ onflushed();
+ });
+ }
 }
 
 
@@ -165,3 +172,63 @@ function _replHistoryMessage() {
  this._historyPrev = Interface.prototype._historyPrev;
  return this._historyPrev();
 }
+
+
+function getTempFile(ready) {
+ var tmpPath = os.tmpdir();
+ if (!tmpPath) {
+ return ready(new Error('no tmpdir available'));
+ }
+ tmpPath = path.join(tmpPath, `${process.pid}-node-repl.tmp`);
+ fs.open(tmpPath, 'wx', 0o600, function(err, fd) {
+ if (err) {
+ return ready(err);
+ }
+ return ready(null, {
+ fd: fd,
+ path: tmpPath
+ });
+ });
+}
+
+// Write data, sync the fd, close it, overwrite the target
+// with a rename, and open a new tmpfile.
+//
+// We use fs.write instead of writeFile because the latter
+// does not accept an fd at the time of writing.
+function writeAndSwapTemp(data, tmpInfo, target, ready) {
+ debug('writing tmp file... %s', tmpInfo.path, data);
+ return fs.write(tmpInfo.fd, data, 0, 'utf8', onwritten);
+
+ function onwritten(err) {
+ if (err) return ready(err);
+ debug('syncing... %s', tmpInfo.path);
+ fs.fsync(tmpInfo.fd, onsync);
+ }
+
+ function onsync(err) {
+ if (err) return ready(err);
+ debug('closing... %s', tmpInfo.path);
+ fs.close(tmpInfo.fd, onclose);
+ }
+
+ function onclose(err) {
+ if (err) return ready(err);
+ debug('rename... %s -> %s', tmpInfo.path, target);
+ fs.rename(tmpInfo.path, target, onrename);
+ }
+
+ function onrename(err) {
+ if (err) return ready(err);
+ debug('re-loading...');
+ getTempFile(ontmpfile);
+ }
+
+ function ontmpfile(err, info) {
+ if (err) return ready(err);
+ tmpInfo.fd = info.fd;
+ tmpInfo.path = info.path;
+ debug('done!');
+ return ready(null);
+ }
+}

src/node.js

@@ -131,9 +131,20 @@
  if (process._forceRepl || NativeModule.require('tty').isatty(0)) {
  // REPL
  var cliRepl = Module.requireRepl();
- cliRepl.createInternalRepl(process.env, function(err, repl) {
+ cliRepl.createInternalRepl(process.env, true, function(err, repl) {
  if (err) {
- throw err;
+ console.error('Encountered error with persistent history support.')
+ console.error('Run with NODE_DEBUG=repl for more information.');
+ if (/repl/.test(process.env.NODE_DEBUG || '')) {
+ console.error(err.stack);
+ }
+ return cliRepl.createInternalRepl(
+ process.env, false, function(err, repl) {
+ if (err) {
+ throw err;
+ }
+ repl.on('exit', process.exit);
+ });
  }
  repl.on('exit', function() {
  if (repl._flushing) {

test/parallel/test-internal-repl-race.js

@@ -0,0 +1,60 @@
+var spawn = require('child_process').spawn;
+var common = require('../common');
+var assert = require('assert');
+var path = require('path');
+var os = require('os');
+var fs = require('fs');
+
+var filename = path.join(common.tmpDir, 'node-history.json');
+
+var config = {
+ env: {
+ NODE_REPL_HISTORY_FILE: filename,
+ NODE_FORCE_READLINE: 1
+ }
+}
+
+var lhs = spawn(process.execPath, ['-i'], config);
+var rhs = spawn(process.execPath, ['-i'], config);
+
+lhs.stdout.pipe(process.stdout);
+rhs.stdout.pipe(process.stdout);
+lhs.stderr.pipe(process.stderr);
+rhs.stderr.pipe(process.stderr);
+
+
+var i = 0;
+var tried = 0;
+var exitcount = 0;
+while (i++ < 100) {
+ lhs.stdin.write('hello = 0' + os.EOL);
+ rhs.stdin.write('OK = 0' + os.EOL);
+}
+lhs.stdin.write('\u0004')
+rhs.stdin.write('\u0004')
+
+lhs.once('exit', onexit)
+rhs.once('exit', onexit)
+
+function onexit() {
+ if (++exitcount !== 2) {
+ return;
+ }
+ check();
+}
+
+function check() {
+ fs.readFile(filename, 'utf8', function(err, data) {
+ if (err) {
+ console.log(err)
+ if (++tried > 100) {
+ throw err;
+ }
+ return setTimeout(check, 15);
+ }
+ assert.doesNotThrow(function() {
+ console.log(data)
+ JSON.parse(data);
+ })
+ })
+}