mirror of
https://github.com/containers/podman.git
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faae3a7065
After a reboot, when we refresh Podman's state, we retrieved the lock from the fresh SHM instance, but we did not mark it as allocated to prevent it being handed out to other containers and pods. Provide a method for marking locks as in-use, and use it when we refresh Podman state after a reboot. Fixes #2900 Signed-off-by: Matthew Heon <matthew.heon@pm.me>
119 lines
2.7 KiB
Go
119 lines
2.7 KiB
Go
package lock
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import (
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"sync"
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"github.com/pkg/errors"
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)
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// Mutex holds a single mutex and whether it has been allocated.
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type Mutex struct {
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id uint32
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lock sync.Mutex
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allocated bool
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}
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// ID retrieves the ID of the mutex
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func (m *Mutex) ID() uint32 {
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return m.id
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}
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// Lock locks the mutex
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func (m *Mutex) Lock() {
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m.lock.Lock()
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}
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// Unlock unlocks the mutex
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func (m *Mutex) Unlock() {
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m.lock.Unlock()
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}
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// Free deallocates the mutex to allow its reuse
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func (m *Mutex) Free() error {
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m.allocated = false
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return nil
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}
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// InMemoryManager is a lock manager that allocates and retrieves local-only
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// locks - that is, they are not multiprocess. This lock manager is intended
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// purely for unit and integration testing and should not be used in production
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// deployments.
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type InMemoryManager struct {
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locks []*Mutex
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numLocks uint32
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localLock sync.Mutex
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}
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// NewInMemoryManager creates a new in-memory lock manager with the given number
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// of locks.
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func NewInMemoryManager(numLocks uint32) (Manager, error) {
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if numLocks == 0 {
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return nil, errors.Errorf("must provide a non-zero number of locks!")
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}
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manager := new(InMemoryManager)
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manager.numLocks = numLocks
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manager.locks = make([]*Mutex, numLocks)
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var i uint32
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for i = 0; i < numLocks; i++ {
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lock := new(Mutex)
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lock.id = i
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manager.locks[i] = lock
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}
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return manager, nil
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}
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// AllocateLock allocates a lock from the manager.
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func (m *InMemoryManager) AllocateLock() (Locker, error) {
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m.localLock.Lock()
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defer m.localLock.Unlock()
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for _, lock := range m.locks {
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if !lock.allocated {
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lock.allocated = true
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return lock, nil
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}
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}
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return nil, errors.Errorf("all locks have been allocated")
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}
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// RetrieveLock retrieves a lock from the manager.
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func (m *InMemoryManager) RetrieveLock(id uint32) (Locker, error) {
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if id >= m.numLocks {
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return nil, errors.Errorf("given lock ID %d is too large - this manager only supports lock indexes up to %d", id, m.numLocks-1)
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}
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return m.locks[id], nil
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}
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// AllocateAndRetrieveLock allocates a lock with the given ID (if not already in
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// use) and returns it.
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func (m *InMemoryManager) AllocateAndRetrieveLock(id uint32) (Locker, error) {
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if id >= m.numLocks {
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return nil, errors.Errorf("given lock ID %d is too large - this manager only supports lock indexes up to %d", id, m.numLocks)
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}
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if m.locks[id].allocated {
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return nil, errors.Errorf("given lock ID %d is already in use, cannot reallocate", id)
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}
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m.locks[id].allocated = true
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return m.locks[id], nil
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}
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// FreeAllLocks frees all locks.
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// This function is DANGEROUS. Please read the full comment in locks.go before
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// trying to use it.
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func (m *InMemoryManager) FreeAllLocks() error {
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for _, lock := range m.locks {
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lock.allocated = false
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}
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return nil
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}
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