ImportantFileWriter

Introducing a class for writing important files, preventing their corruption during writing.

Switched PrefService to use it. Other classes will be switched in future changesets.

TEST=This may affect things using preferences. Make sure that changes in preferences don't get lost, and that you don't get excessive disk activity when changing preferences.

http://crbug.com/10618

Review URL: http://codereview.chromium.org/83001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@14717 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 96 insertions, 0 deletions

diff --git a/chrome/common/important_file_writer_unittest.cc b/chrome/common/important_file_writer_unittest.cc
new file mode 100644
index 0000000..09703a5
--- /dev/null
+++ b/chrome/common/important_file_writer_unittest.cc
@@ -0,0 +1,96 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/common/important_file_writer.h"
+
+#include "base/compiler_specific.h"
+#include "base/file_path.h"
+#include "base/file_util.h"
+#include "base/logging.h"
+#include "base/message_loop.h"
+#include "base/scoped_temp_dir.h"
+#include "base/thread.h"
+#include "base/time.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+std::string GetFileContent(const FilePath& path) {
+  std::string content;
+  if (!file_util::ReadFileToString(path, &content)) {
+    NOTREACHED();
+  }
+  return content;
+}
+
+}  // namespace
+
+class ImportantFileWriterTest : public testing::Test {
+ public:
+  virtual void SetUp() {
+    ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
+    file_ = temp_dir_.path().AppendASCII("test-file");
+  }
+
+ protected:
+  FilePath file_;
+
+ private:
+  MessageLoop loop_;
+  ScopedTempDir temp_dir_;
+};
+
+TEST_F(ImportantFileWriterTest, WithoutBackendThread) {
+  ImportantFileWriter writer(file_, NULL);
+  EXPECT_FALSE(file_util::PathExists(writer.path()));
+  writer.WriteNow("foo");
+  ASSERT_TRUE(file_util::PathExists(writer.path()));
+  EXPECT_EQ("foo", GetFileContent(writer.path()));
+}
+
+TEST_F(ImportantFileWriterTest, WithBackendThread) {
+  base::Thread thread("file_writer_test");
+  ASSERT_TRUE(thread.Start());
+
+  ImportantFileWriter writer(file_, &thread);
+  EXPECT_FALSE(file_util::PathExists(writer.path()));
+  writer.WriteNow("foo");
+  thread.Stop();  // Blocks until all tasks are executed.
+
+  ASSERT_TRUE(file_util::PathExists(writer.path()));
+  EXPECT_EQ("foo", GetFileContent(writer.path()));
+}
+
+TEST_F(ImportantFileWriterTest, ScheduleWrite) {
+  ImportantFileWriter writer(file_, NULL);
+  writer.set_commit_interval(base::TimeDelta::FromMilliseconds(25));
+  writer.ScheduleWrite("foo");
+  MessageLoop::current()->PostDelayedTask(FROM_HERE,
+                                          new MessageLoop::QuitTask(), 100);
+  MessageLoop::current()->Run();
+  ASSERT_TRUE(file_util::PathExists(writer.path()));
+  EXPECT_EQ("foo", GetFileContent(writer.path()));
+}
+
+TEST_F(ImportantFileWriterTest, BatchingWrites) {
+  ImportantFileWriter writer(file_, NULL);
+  writer.set_commit_interval(base::TimeDelta::FromMilliseconds(25));
+  writer.ScheduleWrite("foo");
+  writer.ScheduleWrite("bar");
+  writer.ScheduleWrite("baz");
+  MessageLoop::current()->PostDelayedTask(FROM_HERE,
+                                          new MessageLoop::QuitTask(), 100);
+  MessageLoop::current()->Run();
+  ASSERT_TRUE(file_util::PathExists(writer.path()));
+  EXPECT_EQ("baz", GetFileContent(writer.path()));
+}
+
+TEST_F(ImportantFileWriterTest, WriteOnDestruction) {
+  {
+    ImportantFileWriter writer(file_, NULL);
+    writer.ScheduleWrite("foo");
+  }
+  ASSERT_TRUE(file_util::PathExists(file_));
+  EXPECT_EQ("foo", GetFileContent(file_));
+}