1//===--- LockFileManager.h - File-level locking utility ---------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9#ifndef LLVM_SUPPORT_LOCKFILEMANAGER_H 10#define LLVM_SUPPORT_LOCKFILEMANAGER_H 11 12#include "llvm/ADT/Optional.h" 13#include "llvm/ADT/SmallString.h" 14#include "llvm/ADT/StringRef.h" 15#include "llvm/Support/system_error.h" 16#include <utility> // for std::pair 17 18namespace llvm { 19 20/// \brief Class that manages the creation of a lock file to aid 21/// implicit coordination between different processes. 22/// 23/// The implicit coordination works by creating a ".lock" file alongside 24/// the file that we're coordinating for, using the atomicity of the file 25/// system to ensure that only a single process can create that ".lock" file. 26/// When the lock file is removed, the owning process has finished the 27/// operation. 28class LockFileManager { 29public: 30 /// \brief Describes the state of a lock file. 31 enum LockFileState { 32 /// \brief The lock file has been created and is owned by this instance 33 /// of the object. 34 LFS_Owned, 35 /// \brief The lock file already exists and is owned by some other 36 /// instance. 37 LFS_Shared, 38 /// \brief An error occurred while trying to create or find the lock 39 /// file. 40 LFS_Error 41 }; 42 43private: 44 SmallString<128> FileName; 45 SmallString<128> LockFileName; 46 SmallString<128> UniqueLockFileName; 47 48 Optional<std::pair<std::string, int> > Owner; 49 Optional<error_code> Error; 50 51 LockFileManager(const LockFileManager &) LLVM_DELETED_FUNCTION; 52 LockFileManager &operator=(const LockFileManager &) LLVM_DELETED_FUNCTION; 53 54 static Optional<std::pair<std::string, int> > 55 readLockFile(StringRef LockFileName); 56 57 static bool processStillExecuting(StringRef Hostname, int PID); 58 59public: 60 61 LockFileManager(StringRef FileName); 62 ~LockFileManager(); 63 64 /// \brief Determine the state of the lock file. 65 LockFileState getState() const; 66 67 operator LockFileState() const { return getState(); } 68 69 /// \brief For a shared lock, wait until the owner releases the lock. 70 void waitForUnlock(); 71}; 72 73} // end namespace llvm 74 75#endif // LLVM_SUPPORT_LOCKFILEMANAGER_H 76