1 //===--- LockFileManager.h - File-level locking utility ---------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
9 #ifndef LLVM_SUPPORT_LOCKFILEMANAGER_H
10 #define LLVM_SUPPORT_LOCKFILEMANAGER_H
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
20 /// \brief Class that manages the creation of a lock file to aid
21 /// implicit coordination between different processes.
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
28 class LockFileManager {
30 /// \brief Describes the state of a lock file.
32 /// \brief The lock file has been created and is owned by this instance
35 /// \brief The lock file already exists and is owned by some other
38 /// \brief An error occurred while trying to create or find the lock
44 SmallString<128> LockFileName;
45 SmallString<128> UniqueLockFileName;
47 Optional<std::pair<std::string, int> > Owner;
48 Optional<error_code> Error;
50 LockFileManager(const LockFileManager &) LLVM_DELETED_FUNCTION;
51 LockFileManager &operator=(const LockFileManager &) LLVM_DELETED_FUNCTION;
53 static Optional<std::pair<std::string, int> >
54 readLockFile(StringRef LockFileName);
56 static bool processStillExecuting(StringRef Hostname, int PID);
60 LockFileManager(StringRef FileName);
63 /// \brief Determine the state of the lock file.
64 LockFileState getState() const;
66 operator LockFileState() const { return getState(); }
68 /// \brief For a shared lock, wait until the owner releases the lock.
72 } // end namespace llvm
74 #endif // LLVM_SUPPORT_LOCKFILEMANAGER_H