mirror of
https://github.com/minio/minio.git
synced 2024-12-26 07:05:55 -05:00
1c699d8d3f
This patch re-writes FS backend to support shared backend sharing locks for safe concurrent access across multiple servers.
103 lines
2.4 KiB
Go
103 lines
2.4 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 lock - implements filesystem locking wrappers around an
|
|
// open file descriptor.
|
|
package lock
|
|
|
|
import (
|
|
"os"
|
|
"sync"
|
|
)
|
|
|
|
// RLockedFile represents a read locked file, implements a special
|
|
// closer which only closes the associated *os.File when the ref count.
|
|
// has reached zero, i.e when all the readers have given up their locks.
|
|
type RLockedFile struct {
|
|
*LockedFile
|
|
mutex sync.Mutex
|
|
refs int // Holds read lock refs.
|
|
}
|
|
|
|
// IsClosed - Check if the rlocked file is already closed.
|
|
func (r *RLockedFile) IsClosed() bool {
|
|
r.mutex.Lock()
|
|
defer r.mutex.Unlock()
|
|
return r.refs == 0
|
|
}
|
|
|
|
// IncLockRef - is used by called to indicate lock refs.
|
|
func (r *RLockedFile) IncLockRef() {
|
|
r.mutex.Lock()
|
|
r.refs++
|
|
r.mutex.Unlock()
|
|
}
|
|
|
|
// Close - this closer implements a special closer
|
|
// closes the underlying fd only when the refs
|
|
// reach zero.
|
|
func (r *RLockedFile) Close() (err error) {
|
|
r.mutex.Lock()
|
|
defer r.mutex.Unlock()
|
|
|
|
if r.refs == 0 {
|
|
return os.ErrInvalid
|
|
}
|
|
|
|
r.refs--
|
|
if r.refs == 0 {
|
|
err = r.File.Close()
|
|
}
|
|
|
|
return err
|
|
}
|
|
|
|
// Provides a new initialized read locked struct from *os.File
|
|
func newRLockedFile(lkFile *LockedFile) (*RLockedFile, error) {
|
|
if lkFile == nil {
|
|
return nil, os.ErrInvalid
|
|
}
|
|
|
|
return &RLockedFile{
|
|
LockedFile: lkFile,
|
|
refs: 1,
|
|
}, nil
|
|
}
|
|
|
|
// RLockedOpenFile - returns a wrapped read locked file, if the file
|
|
// doesn't exist at path returns an error.
|
|
func RLockedOpenFile(path string) (*RLockedFile, error) {
|
|
lkFile, err := LockedOpenFile(path, os.O_RDONLY, 0666)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return newRLockedFile(lkFile)
|
|
|
|
}
|
|
|
|
// LockedFile represents a locked file, implements a helper
|
|
// method Size(), represents the size of the underlying object.
|
|
type LockedFile struct {
|
|
*os.File
|
|
size int64
|
|
}
|
|
|
|
// Size - size of the underlying locked file.
|
|
func (l *LockedFile) Size() int64 {
|
|
return l.size
|
|
}
|