ab7d3cd508
Change distributed locking to allow taking bulk locks
across objects, reduces usually 1000 calls to 1.
Also allows for situations where multiple clients sends
delete requests to objects with following names
```
{1,2,3,4,5}
```
```
{5,4,3,2,1}
```
will block and ensure that we do not fail the request
on each other.
104 lines
3.4 KiB
Go
104 lines
3.4 KiB
Go
/*
|
|
* Minio Cloud Storage, (C) 2016 Minio, Inc.
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
package dsync_test
|
|
|
|
import (
|
|
"fmt"
|
|
"sync"
|
|
|
|
. "github.com/minio/minio/pkg/dsync"
|
|
)
|
|
|
|
const WriteLock = -1
|
|
|
|
type lockServer struct {
|
|
mutex sync.Mutex
|
|
// Map of locks, with negative value indicating (exclusive) write lock
|
|
// and positive values indicating number of read locks
|
|
lockMap map[string]int64
|
|
}
|
|
|
|
func (l *lockServer) Lock(args *LockArgs, reply *bool) error {
|
|
l.mutex.Lock()
|
|
defer l.mutex.Unlock()
|
|
if _, *reply = l.lockMap[args.Resources[0]]; !*reply {
|
|
l.lockMap[args.Resources[0]] = WriteLock // No locks held on the given name, so claim write lock
|
|
}
|
|
*reply = !*reply // Negate *reply to return true when lock is granted or false otherwise
|
|
return nil
|
|
}
|
|
|
|
func (l *lockServer) Unlock(args *LockArgs, reply *bool) error {
|
|
l.mutex.Lock()
|
|
defer l.mutex.Unlock()
|
|
var locksHeld int64
|
|
if locksHeld, *reply = l.lockMap[args.Resources[0]]; !*reply { // No lock is held on the given name
|
|
return fmt.Errorf("Unlock attempted on an unlocked entity: %s", args.Resources[0])
|
|
}
|
|
if *reply = locksHeld == WriteLock; !*reply { // Unless it is a write lock
|
|
return fmt.Errorf("Unlock attempted on a read locked entity: %s (%d read locks active)", args.Resources[0], locksHeld)
|
|
}
|
|
delete(l.lockMap, args.Resources[0]) // Remove the write lock
|
|
return nil
|
|
}
|
|
|
|
const ReadLock = 1
|
|
|
|
func (l *lockServer) RLock(args *LockArgs, reply *bool) error {
|
|
l.mutex.Lock()
|
|
defer l.mutex.Unlock()
|
|
var locksHeld int64
|
|
if locksHeld, *reply = l.lockMap[args.Resources[0]]; !*reply {
|
|
l.lockMap[args.Resources[0]] = ReadLock // No locks held on the given name, so claim (first) read lock
|
|
*reply = true
|
|
} else {
|
|
if *reply = locksHeld != WriteLock; *reply { // Unless there is a write lock
|
|
l.lockMap[args.Resources[0]] = locksHeld + ReadLock // Grant another read lock
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (l *lockServer) RUnlock(args *LockArgs, reply *bool) error {
|
|
l.mutex.Lock()
|
|
defer l.mutex.Unlock()
|
|
var locksHeld int64
|
|
if locksHeld, *reply = l.lockMap[args.Resources[0]]; !*reply { // No lock is held on the given name
|
|
return fmt.Errorf("RUnlock attempted on an unlocked entity: %s", args.Resources[0])
|
|
}
|
|
if *reply = locksHeld != WriteLock; !*reply { // A write-lock is held, cannot release a read lock
|
|
return fmt.Errorf("RUnlock attempted on a write locked entity: %s", args.Resources[0])
|
|
}
|
|
if locksHeld > ReadLock {
|
|
l.lockMap[args.Resources[0]] = locksHeld - ReadLock // Remove one of the read locks held
|
|
} else {
|
|
delete(l.lockMap, args.Resources[0]) // Remove the (last) read lock
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (l *lockServer) ForceUnlock(args *LockArgs, reply *bool) error {
|
|
l.mutex.Lock()
|
|
defer l.mutex.Unlock()
|
|
if len(args.UID) != 0 {
|
|
return fmt.Errorf("ForceUnlock called with non-empty UID: %s", args.UID)
|
|
}
|
|
delete(l.lockMap, args.Resources[0]) // Remove the lock (irrespective of write or read lock)
|
|
*reply = true
|
|
return nil
|
|
}
|