Add support for file locking

tests/standalone/io/file_lock_test.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file

[Lasse Reichstein Nielsen, 2015/01/08 11:59:22]

2015

[Søren Gjesse, 2015/01/09 13:06:20]

Done.

+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:io';
+
+import "package:async_helper/async_helper.dart";
+import "package:expect/expect.dart";
+import "package:path/path.dart";
+
+// Check that the file is locked or not.

[Lasse Reichstein Nielsen, 2015/01/08 11:59:22]

that -> whether

[Søren Gjesse, 2015/01/09 13:06:21]

Done.

+check(String path, int start, int end, FileLock mode, {bool locked}) {
+  // Client process returns either 'LOCK FAILED' or 'LOCK SUCCEEDED'.
+  var expected = locked ? 'LOCK FAILED' : 'LOCK SUCCEEDED';
+  var arguments = []
+      ..addAll(Platform.executableArguments)
+      ..add(Platform.script.resolve('file_lock_script.dart').toFilePath())
+      ..add(path)
+      ..add('$start')
+      ..add('$end')
+      ..add(mode == FileLock.EXCLUSIVE ? 'EXCLUSIVE' : 'SHARED');
+    return Process.run(Platform.executable, arguments)
+        .then((ProcessResult result) {
+          if (result.exitCode != 0 || !result.stdout.contains(expected)) {
+            print("Client failed, exit code ${result.exitCode}");
+            print("  stdout:");
+            print(result.stdout);
+            print("  stderr:");
+            print(result.stderr);
+            print("  arguments:");
+            print(arguments);
+            Expect.fail('Client subprocess exit code: ${result.exitCode}');
+          }
+   });
+}
+
+checkLocked(String path,
+            [int start, int end, FileLock mode = FileLock.EXCLUSIVE]) =>
+    check(path, start, end, mode, locked: true);
+
+checkNotLocked(String path,
+               [int start, int end, FileLock mode = FileLock.EXCLUSIVE]) =>
+    check(path, start, end, mode, locked: false);
+
+void testLockWholeFile() {
+  Directory directory = Directory.systemTemp.createTempSync('dart_file_lock');
+  File file = new File(join(directory.path, "file"));
+  file.writeAsBytesSync(new List.filled(10, 0));
+  var raf = file.openSync(mode: WRITE);
+  raf.lockSync();
+  checkLocked(file.path).then((_) {
+    checkLocked(file.path, 0, 2).then((_) {
+      raf.unlockSync();
+      checkNotLocked(file.path).then((_) {
+        raf.closeSync();
+        directory.deleteSync(recursive: true);

[kustermann, 2015/01/08 12:54:28]

Could you do the directory.deleteSync() in a whenComplete(() {}) which is
guaranteed to be executed. This way we never leak temp dirs.

[same for other tests]

[Søren Gjesse, 2015/01/09 13:06:21]

Done.

+      });
+    });
+  });
+}
+
+void testLockWholeFileAsync() {
+  Directory directory = Directory.systemTemp.createTempSync('dart_file_lock');
+  File file = new File(join(directory.path, "file"));
+  file.writeAsBytesSync(new List.filled(10, 0));
+  var raf = file.openSync(mode: WRITE);
+  asyncStart();
+  Future.forEach([
+      () => raf.lock(),
+      () => checkLocked(file.path, 0, 2),
+      () => checkLocked(file.path),
+      () => raf.unlock(),
+      () => checkNotLocked(file.path),
+    ],
+    (f) => f()).then((_) {
+      raf.closeSync();
+      directory.deleteSync(recursive: true);
+      asyncEnd();
+    });
+}
+
+void testLockRange() {
+  Directory directory = Directory.systemTemp.createTempSync('dart_file_lock');
+  File file = new File(join(directory.path, "file"));
+  file.writeAsBytesSync(new List.filled(10, 0));
+  var raf1 = file.openSync(mode: WRITE);
+  var raf2 = file.openSync(mode: WRITE);
+  asyncStart();
+  var tests = [
+      () => raf1.lockSync(2, 3),
+      () => raf2.lockSync(5, 7),
+      () => checkNotLocked(file.path, 0, 2),
+      () => checkLocked(file.path, 0, 3),
+      () => checkNotLocked(file.path, 4, 5),
+      () => checkLocked(file.path, 4, 6),
+      () => checkLocked(file.path, 6),
+      () => checkNotLocked(file.path, 7),
+      () => raf1.unlockSync(2, 3),
+      () => checkNotLocked(file.path, 0, 5),
+      () => checkLocked(file.path, 4, 6),
+      () => checkLocked(file.path, 6),
+      () => checkNotLocked(file.path, 7),
+    ];
+  // On Windows regions unlocked must match regions locked.
+  if (!Platform.isWindows) {
+    tests.addAll([
+        () => raf1.unlockSync(5, 6),
+        () => checkNotLocked(file.path, 0, 6),
+        () => checkLocked(file.path, 6),
+        () => checkNotLocked(file.path, 7),
+        () => raf2.unlockSync(6, 7),
+        () => checkNotLocked(file.path)
+      ]);
+  } else {
+    tests.addAll([
+        () => raf2.unlockSync(5, 7),
+        () => checkNotLocked(file.path)
+      ]);
+  }
+  Future.forEach(tests, (f) => f()).then((_) {
+      raf1.closeSync();
+      raf2.closeSync();
+      directory.deleteSync(recursive: true);
+      asyncEnd();
+    });
+}
+
+void testLockRangeAsync() {
+  Directory directory = Directory.systemTemp.createTempSync('dart_file_lock');
+  File file = new File(join(directory.path, "file"));
+  file.writeAsBytesSync(new List.filled(10, 0));
+  var raf1 = file.openSync(mode: WRITE);
+  var raf2 = file.openSync(mode: WRITE);
+  asyncStart();
+  var tests = [
+      () => raf1.lock(2, 3),
+      () => raf2.lock(5, 7),
+      () => checkNotLocked(file.path, 0, 2),
+      () => checkLocked(file.path, 0, 3),
+      () => checkNotLocked(file.path, 4, 5),
+      () => checkLocked(file.path, 4, 6),
+      () => checkLocked(file.path, 6),
+      () => checkNotLocked(file.path, 7),
+      () => raf1.unlock(2, 3),
+      () => checkNotLocked(file.path, 0, 5),
+      () => checkLocked(file.path, 4, 6),
+      () => checkLocked(file.path, 6),
+      () => checkNotLocked(file.path, 7),
+    ];
+  // On Windows regions unlocked must match regions locked.
+  if (!Platform.isWindows) {
+    tests.addAll([
+        () => raf1.unlock(5, 6),
+        () => checkNotLocked(file.path, 0, 6),
+        () => checkLocked(file.path, 6),
+        () => checkNotLocked(file.path, 7),
+        () => raf2.unlock(6, 7),
+        () => checkNotLocked(file.path)
+      ]);
+  } else {
+    tests.addAll([
+        () => raf2.unlock(5, 7),
+        () => checkNotLocked(file.path)
+      ]);
+  }
+  Future.forEach(tests,
+    (f) => f()).then((_) {
+      raf1.closeSync();
+      raf2.closeSync();
+      directory.deleteSync(recursive: true);
+      asyncEnd();
+    });
+}
+
+void testLockEnd() {
+  Directory directory = Directory.systemTemp.createTempSync('dart_file_lock');
+  File file = new File(join(directory.path, "file"));
+  file.writeAsBytesSync(new List.filled(10, 0));
+  var raf = file.openSync(mode: APPEND);
+  asyncStart();
+  Future.forEach([
+      () => raf.lockSync(2),
+      () => checkNotLocked(file.path, 0, 2),
+      () => checkLocked(file.path, 0, 3),
+      () => checkLocked(file.path, 9),
+      () => raf.writeFromSync(new List.filled(10, 0)),
+      () => checkLocked(file.path, 10),
+      () => checkLocked(file.path, 19),
+      () => raf.unlockSync(2),
+      () => checkNotLocked(file.path)
+    ],
+    (f) => f()).then((_) {
+      raf.closeSync();
+      directory.deleteSync(recursive: true);
+      asyncEnd();
+    });
+}
+
+void testLockEndAsync() {
+  Directory directory = Directory.systemTemp.createTempSync('dart_file_lock');
+  File file = new File(join(directory.path, "file"));
+  file.writeAsBytesSync(new List.filled(10, 0));
+  var raf = file.openSync(mode: APPEND);
+  asyncStart();
+  Future.forEach([
+      () => raf.lock(2),
+      () => checkNotLocked(file.path, 0, 2),
+      () => checkLocked(file.path, 0, 3),
+      () => checkLocked(file.path, 9),
+      () => raf.writeFromSync(new List.filled(10, 0)),
+      () => checkLocked(file.path, 10),
+      () => checkLocked(file.path, 19),
+      () => raf.unlock(2),
+      () => checkNotLocked(file.path)
+    ],
+    (f) => f()).then((_) {
+      raf.closeSync();
+      directory.deleteSync(recursive: true);
+      asyncEnd();
+    });
+}
+
+void testLockShared() {
+  Directory directory = Directory.systemTemp.createTempSync('dart_file_lock');
+  File file = new File(join(directory.path, "file"));
+  file.writeAsBytesSync(new List.filled(10, 0));
+  var raf = file.openSync();
+  asyncStart();
+  Future.forEach([
+      () => raf.lock(null, null, FileLock.SHARED),
+      () => checkLocked(file.path),
+      () => checkLocked(file.path, 0, 2),
+      () => checkNotLocked(file.path, 0, 2, FileLock.SHARED)
+    ],
+    (f) => f()).then((_) {
+      raf.closeSync();
+      directory.deleteSync(recursive: true);
+      asyncEnd();
+    });
+}
+
+void testLockSharedAsync() {
+  Directory directory = Directory.systemTemp.createTempSync('dart_file_lock');
+  File file = new File(join(directory.path, "file"));
+  file.writeAsBytesSync(new List.filled(10, 0));
+  var raf = file.openSync();
+  asyncStart();
+  Future.forEach([
+      () => raf.lock(null, null, FileLock.SHARED),
+      () => checkLocked(file.path),
+      () => checkLocked(file.path, 0, 2),
+      () => checkNotLocked(file.path, 0, 2, FileLock.SHARED)
+    ],
+    (f) => f()).then((_) {
+      raf.closeSync();
+      directory.deleteSync(recursive: true);
+      asyncEnd();
+    });
+}
+
+void main() {
+  testLockWholeFile();
+  testLockWholeFileAsync();
+  testLockRange();
+  testLockRangeAsync();
+  testLockEnd();
+  testLockEndAsync();
+  testLockShared();
+  testLockSharedAsync();

[Lasse Reichstein Nielsen, 2015/01/08 11:59:22]

What happens if the lock range is larger than the file (end > file length)?
Document and test it.

[Søren Gjesse, 2015/01/09 13:06:20]

Done.

+}