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package lock
import (
"github.com/containers/podman/v5/libpod/define"
"github.com/containers/podman/v5/libpod/lock/file"
)
// FileLockManager manages shared memory locks.
type FileLockManager struct {
locks *file.FileLocks
}
// NewFileLockManager makes a new FileLockManager at the specified directory.
func NewFileLockManager(lockPath string) (Manager, error) {
locks, err := file.CreateFileLock(lockPath)
if err != nil {
return nil, err
}
manager := new(FileLockManager)
manager.locks = locks
return manager, nil
}
// OpenFileLockManager opens an existing FileLockManager at the specified directory.
func OpenFileLockManager(path string) (Manager, error) {
locks, err := file.OpenFileLock(path)
if err != nil {
return nil, err
}
manager := new(FileLockManager)
manager.locks = locks
return manager, nil
}
// AllocateLock allocates a new lock from the manager.
func (m *FileLockManager) AllocateLock() (Locker, error) {
semIndex, err := m.locks.AllocateLock()
if err != nil {
return nil, err
}
lock := new(FileLock)
lock.lockID = semIndex
lock.manager = m
return lock, nil
}
// AllocateAndRetrieveLock allocates the lock with the given ID and returns it.
// If the lock is already allocated, error.
func (m *FileLockManager) AllocateAndRetrieveLock(id uint32) (Locker, error) {
lock := new(FileLock)
lock.lockID = id
lock.manager = m
if err := m.locks.AllocateGivenLock(id); err != nil {
return nil, err
}
return lock, nil
}
// RetrieveLock retrieves a lock from the manager given its ID.
func (m *FileLockManager) RetrieveLock(id uint32) (Locker, error) {
lock := new(FileLock)
lock.lockID = id
lock.manager = m
return lock, nil
}
// FreeAllLocks frees all locks in the manager.
// This function is DANGEROUS. Please read the full comment in locks.go before
// trying to use it.
func (m *FileLockManager) FreeAllLocks() error {
return m.locks.DeallocateAllLocks()
}
// AvailableLocks returns the number of available locks. Since this is not
// limited in the file lock implementation, nil is returned.
func (m *FileLockManager) AvailableLocks() (*uint32, error) {
return nil, nil
}
// LocksHeld returns any locks that are presently locked.
// It is not implemented for the file lock backend.
// It ought to be possible, but my motivation to dig into c/storage and add
// trylock semantics to the filelocker implementation for an uncommonly-used
// lock backend is lacking.
func (m *FileLockManager) LocksHeld() ([]uint32, error) {
return nil, define.ErrNotImplemented
}
// FileLock is an individual shared memory lock.
type FileLock struct {
lockID uint32
manager *FileLockManager
}
// ID returns the ID of the lock.
func (l *FileLock) ID() uint32 {
return l.lockID
}
// Lock acquires the lock.
func (l *FileLock) Lock() {
if err := l.manager.locks.LockFileLock(l.lockID); err != nil {
panic(err.Error())
}
}
// Unlock releases the lock.
func (l *FileLock) Unlock() {
if err := l.manager.locks.UnlockFileLock(l.lockID); err != nil {
panic(err.Error())
}
}
// Free releases the lock, allowing it to be reused.
func (l *FileLock) Free() error {
return l.manager.locks.DeallocateLock(l.lockID)
}
|
