28e2075280
trunk/talk git-svn-id: http://webrtc.googlecode.com/svn/trunk@4318 4adac7df-926f-26a2-2b94-8c16560cd09d
71 lines
2.6 KiB
C++
71 lines
2.6 KiB
C++
/*
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* libjingle
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* Copyright 2009, Google Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef TALK_BASE_FILELOCK_H_
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#define TALK_BASE_FILELOCK_H_
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#include <string>
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#include "talk/base/constructormagic.h"
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#include "talk/base/scoped_ptr.h"
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namespace talk_base {
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class FileStream;
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// Implements a very simple cross process lock based on a file.
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// When Lock(...) is called we try to open/create the file in read/write
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// mode without any sharing. (Or locking it with flock(...) on Unix)
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// If the process crash the OS will make sure that the file descriptor
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// is released and another process can accuire the lock.
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// This doesn't work on ancient OSX/Linux versions if used on NFS.
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// (Nfs-client before: ~2.6 and Linux Kernel < 2.6.)
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class FileLock {
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public:
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virtual ~FileLock();
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// Attempts to lock the file. The caller owns the returned
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// lock object. Returns NULL if the file already was locked.
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static FileLock* TryLock(const std::string& path);
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void Unlock();
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protected:
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FileLock(const std::string& path, FileStream* file);
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private:
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void MaybeUnlock();
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std::string path_;
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scoped_ptr<FileStream> file_;
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DISALLOW_EVIL_CONSTRUCTORS(FileLock);
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};
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} // namespace talk_base
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#endif // TALK_BASE_FILELOCK_H_
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