blob: 5258c641fe199660d1a7a5bd2b7d0b7bcbd2bef1 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
package lock
// Manager provides an interface for allocating multiprocess locks.
// Locks returned by Manager MUST be multiprocess - allocating a lock in
// process A and retrieving that lock's ID in process B must return handles for
// the same lock, and locking the lock in A should exclude B from the lock until
// it is unlocked in A.
// All locks must be identified by a UUID (retrieved with Locker's ID() method).
// All locks with a given UUID must refer to the same underlying lock, and it
// must be possible to retrieve the lock given its UUID.
// Each UUID should refer to a unique underlying lock.
// Calls to AllocateLock() must return a unique, unallocated UUID.
// AllocateLock() must fail once all available locks have been allocated.
// Locks are returned to use by calls to Free(), and can subsequently be
// reallocated.
type Manager interface {
// AllocateLock returns an unallocated lock.
// It is guaranteed that the same lock will not be returned again by
// AllocateLock until the returned lock has Free() called on it.
// If all available locks are allocated, AllocateLock will return an
// error.
AllocateLock() (Locker, error)
// RetrieveLock retrieves a lock given its UUID.
// The underlying lock MUST be the same as another other lock with the
// same UUID.
RetrieveLock(id uint32) (Locker, error)
}
// Locker is similar to sync.Locker, but provides a method for freeing the lock
// to allow its reuse.
// All Locker implementations must maintain mutex semantics - the lock only
// allows one caller in the critical section at a time.
// All locks with the same ID must refer to the same underlying lock, even
// if they are within multiple processes.
type Locker interface {
// ID retrieves the lock's ID.
// ID is guaranteed to uniquely identify the lock within the
// Manager - that is, calling RetrieveLock with this ID will return
// another instance of the same lock.
ID() uint32
// Lock locks the lock.
// This call MUST block until it successfully acquires the lock or
// encounters a fatal error.
Lock() error
// Unlock unlocks the lock.
// A call to Unlock() on a lock that is already unlocked lock MUST
// error.
Unlock() error
// Free deallocates the underlying lock, allowing its reuse by other
// pods and containers.
// The lock MUST still be usable after a Free() - some libpod instances
// may still retain Container structs with the old lock. This simply
// advises the manager that the lock may be reallocated.
Free() error
}
|
