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authorphajdan.jr@chromium.org <phajdan.jr@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98>2010-02-19 09:43:08 +0000
committerphajdan.jr@chromium.org <phajdan.jr@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98>2010-02-19 09:43:08 +0000
commit052313bd2f8ef1f994d65be5a5615bb2e9aa19f9 (patch)
tree883e79cee1112b90bd82890f6bffaf84688bb15f /chrome/common/important_file_writer.h
parentf98f581eb3999563a71e8cf35c68420951c9f4e1 (diff)
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Move pref_{member,service} and important_file_writer from chrome/common
to chrome/browser. This is a part of an effort to remove bad dependency of chrome/common on chrome/browser. TEST=unit_tests and ui_tests, just moving code BUG=none Review URL: http://codereview.chromium.org/621004 git-svn-id: svn://svn.chromium.org/chrome/trunk/src@39428 0039d316-1c4b-4281-b951-d872f2087c98
Diffstat (limited to 'chrome/common/important_file_writer.h')
-rw-r--r--chrome/common/important_file_writer.h104
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diff --git a/chrome/common/important_file_writer.h b/chrome/common/important_file_writer.h
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--- a/chrome/common/important_file_writer.h
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@@ -1,104 +0,0 @@
-// 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.
-
-#ifndef CHROME_COMMON_IMPORTANT_FILE_WRITER_H_
-#define CHROME_COMMON_IMPORTANT_FILE_WRITER_H_
-
-#include <string>
-
-#include "base/basictypes.h"
-#include "base/file_path.h"
-#include "base/non_thread_safe.h"
-#include "base/time.h"
-#include "base/timer.h"
-
-namespace base {
-class Thread;
-}
-
-// Helper to ensure that a file won't be corrupted by the write (for example on
-// application crash). Consider a naive way to save an important file F:
-//
-// 1. Open F for writing, truncating it.
-// 2. Write new data to F.
-//
-// It's good when it works, but it gets very bad if step 2. doesn't complete.
-// It can be caused by a crash, a computer hang, or a weird I/O error. And you
-// end up with a broken file.
-//
-// To be safe, we don't start with writing directly to F. Instead, we write to
-// to a temporary file. Only after that write is successful, we rename the
-// temporary file to target filename.
-//
-// If you want to know more about this approach and ext3/ext4 fsync issues, see
-// http://valhenson.livejournal.com/37921.html
-class ImportantFileWriter : public NonThreadSafe {
- public:
- // Used by ScheduleSave to lazily provide the data to be saved. Allows us
- // to also batch data serializations.
- class DataSerializer {
- public:
- virtual ~DataSerializer() {}
-
- // Should put serialized string in |data| and return true on successful
- // serialization. Will be called on the same thread on which
- // ImportantFileWriter has been created.
- virtual bool SerializeData(std::string* data) = 0;
- };
-
- // Initialize the writer.
- // |path| is the name of file to write.
- // All non-const methods, ctor and dtor must be called on the same thread.
- explicit ImportantFileWriter(const FilePath& path);
-
- // You have to ensure that there are no pending writes at the moment
- // of destruction.
- ~ImportantFileWriter();
-
- FilePath path() const { return path_; }
-
- // Returns true if there is a scheduled write pending which has not yet
- // been started.
- bool HasPendingWrite() const;
-
- // Save |data| to target filename. Does not block. If there is a pending write
- // scheduled by ScheduleWrite, it is cancelled.
- void WriteNow(const std::string& data);
-
- // Schedule a save to target filename. Data will be serialized and saved
- // to disk after the commit interval. If another ScheduleWrite is issued
- // before that, only one serialization and write to disk will happen, and
- // the most recent |serializer| will be used. This operation does not block.
- // |serializer| should remain valid through the lifetime of
- // ImportantFileWriter.
- void ScheduleWrite(DataSerializer* serializer);
-
- // Serialize data pending to be saved and execute write on backend thread.
- void DoScheduledWrite();
-
- base::TimeDelta commit_interval() const {
- return commit_interval_;
- }
-
- void set_commit_interval(const base::TimeDelta& interval) {
- commit_interval_ = interval;
- }
-
- private:
- // Path being written to.
- const FilePath path_;
-
- // Timer used to schedule commit after ScheduleWrite.
- base::OneShotTimer<ImportantFileWriter> timer_;
-
- // Serializer which will provide the data to be saved.
- DataSerializer* serializer_;
-
- // Time delta after which scheduled data will be written to disk.
- base::TimeDelta commit_interval_;
-
- DISALLOW_COPY_AND_ASSIGN(ImportantFileWriter);
-};
-
-#endif // CHROME_COMMON_IMPORTANT_FILE_WRITER_H_