Class that manages the creation of a lock file to aid implicit coordination between different processes. More...

#include "llvm/Support/LockFileManager.h"

Public Types
enum	LockFileState { LFS_Owned , LFS_Shared , LFS_Error }
	Describes the state of a lock file. More...

enum	WaitForUnlockResult { Res_Success , Res_OwnerDied , Res_Timeout }
	Describes the result of waiting for the owner to release the lock. More...

Public Member Functions
	LockFileManager (StringRef FileName)

	~LockFileManager ()

LockFileState	getState () const
	Determine the state of the lock file.

	operator LockFileState () const

WaitForUnlockResult	waitForUnlock (const unsigned MaxSeconds=90)
	For a shared lock, wait until the owner releases the lock.

std::error_code	unsafeRemoveLockFile ()
	Remove the lock file.

std::string	getErrorMessage () const
	Get error message, or "" if there is no error.

void	setError (const std::error_code &EC, StringRef ErrorMsg="")
	Set error and error message.

Detailed Description

Class that manages the creation of a lock file to aid implicit coordination between different processes.

The implicit coordination works by creating a ".lock" file alongside the file that we're coordinating for, using the atomicity of the file system to ensure that only a single process can create that ".lock" file. When the lock file is removed, the owning process has finished the operation.

Definition at line 27 of file LockFileManager.h.

Member Enumeration Documentation

◆ LockFileState

enum llvm::LockFileManager::LockFileState

Describes the state of a lock file.

Enumerator
LFS_Owned	The lock file has been created and is owned by this instance of the object.
LFS_Shared	The lock file already exists and is owned by some other instance.
LFS_Error	An error occurred while trying to create or find the lock file.

Definition at line 30 of file LockFileManager.h.

◆ WaitForUnlockResult

enum llvm::LockFileManager::WaitForUnlockResult

Describes the result of waiting for the owner to release the lock.

Enumerator
Res_Success	The lock was released successfully.
Res_OwnerDied	Owner died while holding the lock.
Res_Timeout	Reached timeout while waiting for the owner to release the lock.

Definition at line 43 of file LockFileManager.h.

Constructor & Destructor Documentation

◆ LockFileManager()

LockFileManager::LockFileManager ( StringRef FileName )

Definition at line 160 of file LockFileManager.cpp.

References llvm::raw_fd_ostream::clear_error(), llvm::raw_fd_ostream::close(), llvm::sys::fs::create_link(), llvm::sys::fs::createUniqueFile(), llvm::raw_fd_ostream::error(), llvm::sys::fs::exists(), llvm::file_exists, getHostID(), llvm::sys::Process::getProcessId(), llvm::raw_fd_ostream::has_error(), llvm::sys::fs::make_absolute(), llvm::sys::fs::remove(), setError(), llvm::raw_string_ostream::str(), and llvm::SmallString< InternalLen >::str().

◆ ~LockFileManager()

LockFileManager::~LockFileManager ( )

Definition at line 282 of file LockFileManager.cpp.

References llvm::sys::DontRemoveFileOnSignal(), getState(), LFS_Owned, and llvm::sys::fs::remove().

Member Function Documentation

◆ getErrorMessage()

std::string LockFileManager::getErrorMessage ( ) const

Get error message, or "" if there is no error.

Definition at line 270 of file LockFileManager.cpp.

References llvm::raw_string_ostream::str().

◆ getState()

LockFileManager::LockFileState LockFileManager::getState ( ) const

Determine the state of the lock file.

Definition at line 260 of file LockFileManager.cpp.

References LFS_Error, LFS_Owned, and LFS_Shared.

Referenced by operator LockFileState(), waitForUnlock(), and ~LockFileManager().

◆ operator LockFileState()

llvm::LockFileManager::operator LockFileState ( ) const

inline

Definition at line 77 of file LockFileManager.h.

References getState().

◆ setError()

void llvm::LockFileManager::setError	(	const std::error_code &	EC,
		StringRef	ErrorMsg = `""`
	)

inline

Set error and error message.

Definition at line 92 of file LockFileManager.h.

Referenced by LockFileManager().

◆ unsafeRemoveLockFile()

std::error_code LockFileManager::unsafeRemoveLockFile ( )

Remove the lock file.

This may delete a different lock file than the one previously read if there is a race.

Definition at line 326 of file LockFileManager.cpp.

References llvm::sys::fs::remove().

◆ waitForUnlock()

LockFileManager::WaitForUnlockResult LockFileManager::waitForUnlock ( const unsigned MaxSeconds = 90 )

For a shared lock, wait until the owner releases the lock.

Total timeout for the file to appear is ~1.5 minutes.

Parameters

MaxSeconds the maximum total wait time in seconds.

Definition at line 295 of file LockFileManager.cpp.

References llvm::sys::fs::access(), llvm::SmallString< InternalLen >::c_str(), llvm::sys::fs::Exist, llvm::sys::fs::exists(), getState(), LFS_Shared, llvm::no_such_file_or_directory, Res_OwnerDied, Res_Success, Res_Timeout, and llvm::ExponentialBackoff::waitForNextAttempt().

The documentation for this class was generated from the following files:

include/llvm/Support/LockFileManager.h
lib/Support/LockFileManager.cpp

Public Types

Public Member Functions