minio/cmd/lock-rpc-server-common.go

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/*
* MinIO Cloud Storage, (C) 2016, 2017, 2018, 2019 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 cmd
import (
"context"
"errors"
"time"
"github.com/minio/minio/cmd/logger"
)
// nameLockRequesterInfoPair is a helper type for lock maintenance
type nameLockRequesterInfoPair struct {
name string
lri lockRequesterInfo
}
// Similar to removeEntry but only removes an entry only if the lock entry exists in map.
func (l *localLocker) removeEntryIfExists(nlrip nameLockRequesterInfoPair) {
// Check if entry is still in map (could have been removed altogether by 'concurrent' (R)Unlock of last entry)
if lri, ok := l.lockMap[nlrip.name]; ok {
if !l.removeEntry(nlrip.name, nlrip.lri.UID, &lri) {
// Remove failed, in case it is a:
if nlrip.lri.Writer {
// Writer: this should never happen as the whole (mapped) entry should have been deleted
reqInfo := (&logger.ReqInfo{}).AppendTags("name", nlrip.name)
reqInfo.AppendTags("uid", nlrip.lri.UID)
ctx := logger.SetReqInfo(context.Background(), reqInfo)
logger.LogIf(ctx, errors.New("Lock maintenance failed to remove entry for write lock (should never happen)"))
} // Reader: this can happen if multiple read locks were active and
// the one we are looking for has been released concurrently (so it is fine).
} // Removal went okay, all is fine.
}
}
// removeEntry either, based on the uid of the lock message, removes a single entry from the
// lockRequesterInfo array or the whole array from the map (in case of a write lock or last read lock)
func (l *localLocker) removeEntry(name, uid string, lri *[]lockRequesterInfo) bool {
// Find correct entry to remove based on uid.
for index, entry := range *lri {
if entry.UID == uid {
if len(*lri) == 1 {
// Remove the (last) lock.
delete(l.lockMap, name)
} else {
// Remove the appropriate read lock.
*lri = append((*lri)[:index], (*lri)[index+1:]...)
l.lockMap[name] = *lri
}
return true
}
}
// None found return false, perhaps entry removed in previous run.
return false
}
// getLongLivedLocks returns locks that are older than a certain time and
// have not been 'checked' for validity too soon enough
func getLongLivedLocks(m map[string][]lockRequesterInfo, interval time.Duration) []nameLockRequesterInfoPair {
rslt := []nameLockRequesterInfoPair{}
for name, lriArray := range m {
for idx := range lriArray {
// Check whether enough time has gone by since last check
if time.Since(lriArray[idx].TimeLastCheck) >= interval {
rslt = append(rslt, nameLockRequesterInfoPair{name: name, lri: lriArray[idx]})
lriArray[idx].TimeLastCheck = UTCNow()
}
}
}
return rslt
}