60 lines
2.4 KiB
C++
60 lines
2.4 KiB
C++
// *****************************************************************************
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// * This file is part of the FreeFileSync project. It is distributed under *
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// * GNU General Public License: https://www.gnu.org/licenses/gpl-3.0 *
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// * Copyright (C) Zenju (zenju AT freefilesync DOT org) - All Rights Reserved *
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// *****************************************************************************
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#ifndef DIR_LOCK_H_81740832174954356
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#define DIR_LOCK_H_81740832174954356
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#include <memory>
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#include <chrono>
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#include <functional>
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#include <zen/file_error.h>
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namespace fff
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{
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/* RAII structure to place a directory lock against other FFS processes:
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- recursive locking supported, even with alternate lockfile names, e.g. via symlinks, network mounts, case-differences etc.
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- ownership shared between all object instances refering to a specific lock location(= GUID)
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- can be copied safely and efficiently! (ref-counting)
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- detects and resolves abandoned locks (instantly if lock is associated with local pc, else after 30 seconds)
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- temporary locks created during abandoned lock resolution keep "lockFilePath"'s extension
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- race-free (Windows, almost on Linux(NFS))
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- NOT thread-safe! (1. global LockAdmin 2. locks for directory aliases should be created sequentially to detect duplicate locks!) */
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//intermediate locks created by DirLock use this extension, too:
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constexpr ZstringView LOCK_FILE_ENDING = Zstr(".ffs_lock"); //don't use Zstring as global constant: avoid static initialization order problem in global namespace!
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//while waiting for the lock
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using DirLockCallback = std::function<void(std::wstring&& msg)>; //throw X
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class DirLock
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{
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public:
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DirLock(const Zstring& folderPath,
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const DirLockCallback& notifyStatus, //callback only used during construction
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std::chrono::milliseconds cbInterval) :
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DirLock(folderPath, Zstring(Zstr("sync")) + LOCK_FILE_ENDING, notifyStatus, cbInterval) {} //throw FileError
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DirLock(const Zstring& folderPath,
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const Zstring& fileName,
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const DirLockCallback& notifyStatus,
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std::chrono::milliseconds cbInterval); //throw FileError
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private:
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class LockAdmin;
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class SharedDirLock;
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std::shared_ptr<SharedDirLock> sharedLock_;
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};
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namespace impl //declare for unit tests:
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{
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Zstring getAbandonedLockFileName(const Zstring& lockFilePath); //throw FileError
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}
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}
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#endif //DIR_LOCK_H_81740832174954356
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