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 <system_error>
16 #include <utility> // for std::pair
19 using std::error_code;
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
43 /// \brief Describes the result of waiting for the owner to release the lock.
44 enum WaitForUnlockResult {
45 /// \brief The lock was released successfully.
47 /// \brief Owner died while holding the lock.
49 /// \brief Reached timeout while waiting for the owner to release the lock.
54 SmallString<128> FileName;
55 SmallString<128> LockFileName;
56 SmallString<128> UniqueLockFileName;
58 Optional<std::pair<std::string, int> > Owner;
59 Optional<error_code> Error;
61 LockFileManager(const LockFileManager &) LLVM_DELETED_FUNCTION;
62 LockFileManager &operator=(const LockFileManager &) LLVM_DELETED_FUNCTION;
64 static Optional<std::pair<std::string, int> >
65 readLockFile(StringRef LockFileName);
67 static bool processStillExecuting(StringRef Hostname, int PID);
71 LockFileManager(StringRef FileName);
74 /// \brief Determine the state of the lock file.
75 LockFileState getState() const;
77 operator LockFileState() const { return getState(); }
79 /// \brief For a shared lock, wait until the owner releases the lock.
80 WaitForUnlockResult waitForUnlock();
83 } // end namespace llvm
85 #endif // LLVM_SUPPORT_LOCKFILEMANAGER_H