pathlocks.hh File Reference

#include "lix/libutil/error.hh"
#include "lix/libutil/file-descriptor.hh"
#include "lix/libutil/result.hh"
#include "lix/libutil/types.hh"
#include <chrono>
#include <kj/async.h>
#include <kj/common.h>

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Classes
class	nix::PathLock
class	nix::FdLock
struct	nix::FdLock::DontWait

Typedefs
using	nix::PathLocks = std::list<PathLock>

Enumerations
enum	LockType { ltRead , ltWrite }

Functions
AutoCloseFD	nix::openLockFile (const Path &path, bool create)
void	nix::lockFile (int fd, LockType lockType, NeverAsync)
kj::Promise< Result< void > >	nix::lockFileAsync (int fd, LockType lockType)
bool	nix::unsafeLockFileSingleThreaded (int fd, LockType lockType, std::chrono::seconds timeout)
bool	nix::tryLockFile (int fd, LockType lockType)
void	nix::unlockFile (int fd)
kj::Promise< Result< PathLock > >	nix::lockPathAsync (const Path &path, std::string_view waitMsg)
PathLock	nix::lockPath (const Path &path, std::string_view waitMsg, NeverAsync)
std::optional< PathLock >	nix::tryLockPath (const Path &path)
PathLocks	nix::lockPaths (const PathSet &paths, std::string_view waitMsg, NeverAsync)
std::optional< PathLocks >	nix::tryLockPaths (const PathSet &paths)

Function Documentation

openLockFile()

AutoCloseFD nix::openLockFile	(	const Path &	path,
		bool	create )

Open (possibly create) a lock file and return the file descriptor. -1 is returned if create is false and the lock could not be opened because it doesn't exist. Any other error throws an exception.

unsafeLockFileSingleThreaded()

bool nix::unsafeLockFileSingleThreaded	(	int	fd,
		LockType	lockType,
		std::chrono::seconds	timeout )

Same as lockFile, but with a timeout. This timeout uses the POSIX alarm facility and a SIGALRM handler. Using this function from multiple threads in the same process is not safe: all SIGALRM handlers set previously will be overwritten while this function is executing and are restored on return.