llvm::LockFileManager Class Reference

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

#include "llvm/Support/LockFileManager.h"

Inheritance diagram for llvm::LockFileManager:

Public Member Functions
	LockFileManager (StringRef FileName)
	Does not try to acquire the lock.
Expected< bool >	tryLock () override
	Tries to acquire the lock without blocking.
WaitForUnlockResult	waitForUnlockFor (std::chrono::seconds MaxSeconds) override
	For a shared lock, wait until the owner releases the lock.
std::error_code	unsafeMaybeUnlock () override
	Remove the lock file.
	~LockFileManager () override
	Unlocks the lock if previously acquired by tryLock().
Public Member Functions inherited from llvm::AdvisoryLock
virtual Expected< bool >	tryLock ()=0
	Tries to acquire ownership of the lock without blocking.
virtual WaitForUnlockResult	waitForUnlockFor (std::chrono::seconds MaxSeconds)=0
	For a lock owned by someone else, wait until it is unlocked.
virtual std::error_code	unsafeMaybeUnlock ()=0
	For a lock owned by someone else, unlock it.
virtual	~AdvisoryLock ()=default
	Unlocks the lock if its ownership was previously acquired by tryLock().

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, 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.

Constructor & Destructor Documentation

LockFileManager()

LockFileManager::LockFileManager

(

StringRef

FileName

)

Does not try to acquire the lock.

Definition at line 160 of file LockFileManager.cpp.

~LockFileManager()

LockFileManager::~LockFileManager ( )

override

Unlocks the lock if previously acquired by tryLock().

Definition at line 248 of file LockFileManager.cpp.

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

Member Function Documentation

tryLock()

Expected< bool > LockFileManager::tryLock ( )

overridevirtual

Tries to acquire the lock without blocking.

Returns

true if the lock was successfully acquired, false if the lock is already held by someone else, or Error in case of unexpected failure.

Implements llvm::AdvisoryLock.

Definition at line 163 of file LockFileManager.cpp.

References assert(), llvm::raw_fd_ostream::clear_error(), llvm::raw_fd_ostream::close(), llvm::sys::fs::create_link(), llvm::createStringError(), 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(), and llvm::sys::fs::remove().

Referenced by llvm::AMDGPUSplitModulePass::run().

unsafeMaybeUnlock()

std::error_code LockFileManager::unsafeMaybeUnlock ( )

overridevirtual

Remove the lock file.

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

Implements llvm::AdvisoryLock.

Definition at line 290 of file LockFileManager.cpp.

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

Referenced by llvm::AMDGPUSplitModulePass::run().

waitForUnlockFor()

WaitForUnlockResult LockFileManager::waitForUnlockFor ( std::chrono::seconds  MaxSeconds )

overridevirtual

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

Parameters

MaxSeconds

the maximum total wait time in seconds.

Implements llvm::AdvisoryLock.

Definition at line 261 of file LockFileManager.cpp.

References llvm::sys::fs::access(), assert(), llvm::SmallString< InternalLen >::c_str(), llvm::sys::fs::Exist, llvm::no_such_file_or_directory, llvm::OwnerDied, llvm::Success, llvm::Timeout, and llvm::ExponentialBackoff::waitForNextAttempt().

Referenced by llvm::AMDGPUSplitModulePass::run().

---

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

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