2018-06-06 10:51:56 +02:00
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/*
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2019-04-09 20:39:42 +02:00
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* MinIO Cloud Storage, (C) 2018, 2019 MinIO, Inc.
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2018-06-06 10:51:56 +02:00
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package cmd
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import (
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"fmt"
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"sync"
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"time"
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2019-11-13 21:17:45 +01:00
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"github.com/minio/minio/pkg/dsync"
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2018-06-06 10:51:56 +02:00
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)
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// lockRequesterInfo stores various info from the client for each lock that is requested.
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type lockRequesterInfo struct {
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2019-11-13 21:17:45 +01:00
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Writer bool // Bool whether write or read lock.
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UID string // UID to uniquely identify request of client.
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Timestamp time.Time // Timestamp set at the time of initialization.
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TimeLastCheck time.Time // Timestamp for last check of validity of lock.
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Source string // Contains line, function and filename reqesting the lock.
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2018-06-06 10:51:56 +02:00
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}
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// isWriteLock returns whether the lock is a write or read lock.
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func isWriteLock(lri []lockRequesterInfo) bool {
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2019-01-24 16:22:14 +01:00
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return len(lri) == 1 && lri[0].Writer
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2018-06-06 10:51:56 +02:00
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}
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2019-11-13 21:17:45 +01:00
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// localLocker implements Dsync.NetLocker
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type localLocker struct {
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mutex sync.Mutex
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endpoint Endpoint
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lockMap map[string][]lockRequesterInfo
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2018-06-06 10:51:56 +02:00
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}
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2019-11-13 21:17:45 +01:00
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func (l *localLocker) String() string {
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return l.endpoint.String()
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2018-06-06 10:51:56 +02:00
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}
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func (l *localLocker) Lock(args dsync.LockArgs) (reply bool, err error) {
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l.mutex.Lock()
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defer l.mutex.Unlock()
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_, isLockTaken := l.lockMap[args.Resource]
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if !isLockTaken { // No locks held on the given name, so claim write lock
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l.lockMap[args.Resource] = []lockRequesterInfo{
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{
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2019-11-13 21:17:45 +01:00
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Writer: true,
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Source: args.Source,
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UID: args.UID,
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Timestamp: UTCNow(),
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TimeLastCheck: UTCNow(),
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2018-06-06 10:51:56 +02:00
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},
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}
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}
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// return reply=true if lock was granted.
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return !isLockTaken, nil
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}
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func (l *localLocker) Unlock(args dsync.LockArgs) (reply bool, err error) {
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l.mutex.Lock()
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defer l.mutex.Unlock()
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var lri []lockRequesterInfo
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if lri, reply = l.lockMap[args.Resource]; !reply {
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// No lock is held on the given name
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return reply, fmt.Errorf("Unlock attempted on an unlocked entity: %s", args.Resource)
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}
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if reply = isWriteLock(lri); !reply {
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// Unless it is a write lock
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return reply, fmt.Errorf("Unlock attempted on a read locked entity: %s (%d read locks active)", args.Resource, len(lri))
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}
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if !l.removeEntry(args.Resource, args.UID, &lri) {
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return false, fmt.Errorf("Unlock unable to find corresponding lock for uid: %s", args.UID)
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}
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return true, nil
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}
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2019-11-13 21:17:45 +01:00
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// removeEntry based on the uid of the lock message, removes a single entry from the
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// lockRequesterInfo array or the whole array from the map (in case of a write lock
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// or last read lock)
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func (l *localLocker) removeEntry(name, uid string, lri *[]lockRequesterInfo) bool {
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// Find correct entry to remove based on uid.
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for index, entry := range *lri {
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if entry.UID == uid {
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if len(*lri) == 1 {
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// Remove the write lock.
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delete(l.lockMap, name)
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} else {
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// Remove the appropriate read lock.
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*lri = append((*lri)[:index], (*lri)[index+1:]...)
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l.lockMap[name] = *lri
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}
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return true
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}
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}
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// None found return false, perhaps entry removed in previous run.
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return false
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}
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2018-06-06 10:51:56 +02:00
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func (l *localLocker) RLock(args dsync.LockArgs) (reply bool, err error) {
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l.mutex.Lock()
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defer l.mutex.Unlock()
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lrInfo := lockRequesterInfo{
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Writer: false,
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Source: args.Source,
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UID: args.UID,
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Timestamp: UTCNow(),
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TimeLastCheck: UTCNow(),
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2018-06-06 10:51:56 +02:00
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}
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if lri, ok := l.lockMap[args.Resource]; ok {
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if reply = !isWriteLock(lri); reply {
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// Unless there is a write lock
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l.lockMap[args.Resource] = append(l.lockMap[args.Resource], lrInfo)
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}
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} else {
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// No locks held on the given name, so claim (first) read lock
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l.lockMap[args.Resource] = []lockRequesterInfo{lrInfo}
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reply = true
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}
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return reply, nil
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}
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func (l *localLocker) RUnlock(args dsync.LockArgs) (reply bool, err error) {
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l.mutex.Lock()
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defer l.mutex.Unlock()
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var lri []lockRequesterInfo
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if lri, reply = l.lockMap[args.Resource]; !reply {
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// No lock is held on the given name
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return reply, fmt.Errorf("RUnlock attempted on an unlocked entity: %s", args.Resource)
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}
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if reply = !isWriteLock(lri); !reply {
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// A write-lock is held, cannot release a read lock
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return reply, fmt.Errorf("RUnlock attempted on a write locked entity: %s", args.Resource)
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}
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if !l.removeEntry(args.Resource, args.UID, &lri) {
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return false, fmt.Errorf("RUnlock unable to find corresponding read lock for uid: %s", args.UID)
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}
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return reply, nil
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}
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2019-01-24 16:22:14 +01:00
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func (l *localLocker) DupLockMap() map[string][]lockRequesterInfo {
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l.mutex.Lock()
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defer l.mutex.Unlock()
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lockCopy := make(map[string][]lockRequesterInfo)
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for k, v := range l.lockMap {
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2019-02-13 13:59:36 +01:00
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lockCopy[k] = append(lockCopy[k], v...)
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2019-01-24 16:22:14 +01:00
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}
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return lockCopy
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}
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2019-11-13 21:17:45 +01:00
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func (l *localLocker) Close() error {
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return nil
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}
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2019-11-20 02:42:27 +01:00
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// Local locker is always online.
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func (l *localLocker) IsOnline() bool {
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return true
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}
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2019-11-26 01:39:43 +01:00
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func (l *localLocker) Expired(args dsync.LockArgs) (expired bool, err error) {
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l.mutex.Lock()
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defer l.mutex.Unlock()
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// Lock found, proceed to verify if belongs to given uid.
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if lri, ok := l.lockMap[args.Resource]; ok {
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// Check whether uid is still active
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for _, entry := range lri {
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if entry.UID == args.UID {
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return false, nil
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}
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}
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}
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return true, nil
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}
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// Similar to removeEntry but only removes an entry only if the lock entry exists in map.
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// Caller must hold 'l.mutex' lock.
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func (l *localLocker) removeEntryIfExists(nlrip nameLockRequesterInfoPair) {
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// Check if entry is still in map (could have been removed altogether by 'concurrent' (R)Unlock of last entry)
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if lri, ok := l.lockMap[nlrip.name]; ok {
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// Even if the entry exists, it may not be the same entry which was
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// considered as expired, so we simply an attempt to remove it if its
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// not possible there is nothing we need to do.
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l.removeEntry(nlrip.name, nlrip.lri.UID, &lri)
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}
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}
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2019-11-13 21:17:45 +01:00
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func newLocker(endpoint Endpoint) *localLocker {
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return &localLocker{
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endpoint: endpoint,
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lockMap: make(map[string][]lockRequesterInfo),
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}
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}
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