270 lines
8.6 KiB
Go
270 lines
8.6 KiB
Go
/*
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* Minio Cloud Storage, (C) 2016, 2017 Minio, Inc.
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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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"crypto/rand"
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"fmt"
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"time"
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)
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type statusType string
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const (
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runningStatus statusType = "Running"
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blockedStatus statusType = "Blocked"
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)
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type lockType string
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const (
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debugRLockStr lockType = "RLock"
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debugWLockStr lockType = "WLock"
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)
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// debugLockInfo - represents a single lock's information, uniquely identified by opsID.
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// See debugLockInfoPerVolumePath for more context.
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type debugLockInfo struct {
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// "RLock" or "WLock".
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lType lockType
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// Contains the backtrace of incl. the function which called (r)(un)lock.
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lockSource string
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// Status can be running/blocked.
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status statusType
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// Time of last status update.
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since time.Time
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}
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// debugLockInfoPerVolumePath - lock state information on all locks held on (volume, path).
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type debugLockInfoPerVolumePath struct {
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counters *lockStat // Holds stats of lock held on (volume, path)
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lockInfo map[string]debugLockInfo // Lock information per operation ID.
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}
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// LockInfoOriginMismatch - represents error when lock origin don't match.
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type LockInfoOriginMismatch struct {
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volume string
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path string
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opsID string
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lockSource string
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}
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func (l LockInfoOriginMismatch) Error() string {
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return fmt.Sprintf("No lock state stored for the lock originated at \"%s\", for <volume> %s, <path> %s, <opsID> %s",
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l.lockSource, l.volume, l.path, l.opsID)
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}
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// LockInfoVolPathMissing - represents error when lock information is missing for a given (volume, path).
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type LockInfoVolPathMissing struct {
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volume string
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path string
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}
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func (l LockInfoVolPathMissing) Error() string {
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return fmt.Sprintf("No entry in debug Lock Map for Volume: %s, path: %s", l.volume, l.path)
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}
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// LockInfoOpsIDNotFound - represents error when lock info entry for a given operation ID doesn't exist.
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type LockInfoOpsIDNotFound struct {
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volume string
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path string
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opsID string
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}
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func (l LockInfoOpsIDNotFound) Error() string {
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return fmt.Sprintf("No entry in lock info for <Operation ID> %s, <volume> %s, <path> %s", l.opsID, l.volume, l.path)
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}
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// LockInfoStateNotBlocked - represents error when lock info isn't in blocked state when it should be.
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type LockInfoStateNotBlocked struct {
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volume string
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path string
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opsID string
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}
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func (l LockInfoStateNotBlocked) Error() string {
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return fmt.Sprintf("Lock state should be \"Blocked\" for <volume> %s, <path> %s, <opsID> %s", l.volume, l.path, l.opsID)
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}
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// Initialize lock info for given (volume, path).
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func (n *nsLockMap) initLockInfoForVolumePath(param nsParam) {
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n.debugLockMap[param] = &debugLockInfoPerVolumePath{
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lockInfo: make(map[string]debugLockInfo),
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counters: &lockStat{},
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}
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}
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// Change the state of the lock from Blocked to Running.
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func (n *nsLockMap) statusBlockedToRunning(param nsParam, lockSource, opsID string, readLock bool) error {
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// This function is called outside nsLockMap.mutex.Lock(), so must be held explicitly.
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n.lockMapMutex.Lock()
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defer n.lockMapMutex.Unlock()
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// Check whether the lock info entry for <volume, path> pair already exists.
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_, ok := n.debugLockMap[param]
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if !ok {
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return traceError(LockInfoVolPathMissing{param.volume, param.path})
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}
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// Check whether lock info entry for the given `opsID` exists.
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lockInfo, ok := n.debugLockMap[param].lockInfo[opsID]
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if !ok {
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return traceError(LockInfoOpsIDNotFound{param.volume, param.path, opsID})
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}
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// Check whether lockSource is same.
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if lockInfo.lockSource != lockSource {
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return traceError(LockInfoOriginMismatch{param.volume, param.path, opsID, lockSource})
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}
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// Status of the lock should be set to "Blocked".
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if lockInfo.status != blockedStatus {
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return traceError(LockInfoStateNotBlocked{param.volume, param.path, opsID})
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}
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// Change lock status to running and update the time.
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n.debugLockMap[param].lockInfo[opsID] = newDebugLockInfo(lockSource, runningStatus, readLock)
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// Update global lock stats.
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n.counters.lockGranted()
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// Update (volume, pair) lock stats.
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n.debugLockMap[param].counters.lockGranted()
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return nil
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}
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// newDebugLockInfo - Constructs a debugLockInfo value given lock source, status and type.
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func newDebugLockInfo(lockSource string, status statusType, readLock bool) debugLockInfo {
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var lType lockType
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if readLock {
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lType = debugRLockStr
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} else {
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lType = debugWLockStr
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}
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return debugLockInfo{
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lockSource: lockSource,
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lType: lType,
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status: status,
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since: UTCNow(),
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}
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}
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// Change the state of the lock to Blocked.
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func (n *nsLockMap) statusNoneToBlocked(param nsParam, lockSource, opsID string, readLock bool) error {
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_, ok := n.debugLockMap[param]
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if !ok {
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// Lock info entry for (volume, pair) doesn't exist, initialize it.
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n.initLockInfoForVolumePath(param)
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}
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// Mark lock status blocked for given opsID.
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n.debugLockMap[param].lockInfo[opsID] = newDebugLockInfo(lockSource, blockedStatus, readLock)
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// Update global lock stats.
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n.counters.lockWaiting()
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// Update (volume, path) lock stats.
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n.debugLockMap[param].counters.lockWaiting()
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return nil
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}
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// Change the state of the lock from Blocked to none.
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func (n *nsLockMap) statusBlockedToNone(param nsParam, lockSource, opsID string, readLock bool) error {
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_, ok := n.debugLockMap[param]
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if !ok {
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return traceError(LockInfoVolPathMissing{param.volume, param.path})
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}
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// Check whether lock info entry for the given `opsID` exists.
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lockInfo, ok := n.debugLockMap[param].lockInfo[opsID]
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if !ok {
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return traceError(LockInfoOpsIDNotFound{param.volume, param.path, opsID})
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}
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// Check whether lockSource is same.
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if lockInfo.lockSource != lockSource {
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return traceError(LockInfoOriginMismatch{param.volume, param.path, opsID, lockSource})
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}
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// Status of the lock should be set to "Blocked".
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if lockInfo.status != blockedStatus {
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return traceError(LockInfoStateNotBlocked{param.volume, param.path, opsID})
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}
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// Clear the status by removing the entry for the given `opsID`.
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delete(n.debugLockMap[param].lockInfo, opsID)
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// Update global lock stats.
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n.counters.lockTimedOut()
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// Update (volume, path) lock stats.
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n.debugLockMap[param].counters.lockTimedOut()
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return nil
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}
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// deleteLockInfoEntry - Deletes the lock information for given (volume, path).
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// Called when nsLk.ref count is 0.
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func (n *nsLockMap) deleteLockInfoEntryForVolumePath(param nsParam) error {
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// delete the lock info for the given operation.
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if _, found := n.debugLockMap[param]; !found {
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return traceError(LockInfoVolPathMissing{param.volume, param.path})
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}
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// The following stats update is relevant only in case of a
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// ForceUnlock. In case of the last unlock on a (volume,
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// path), this would be a no-op.
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volumePathLocks := n.debugLockMap[param]
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for _, lockInfo := range volumePathLocks.lockInfo {
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granted := lockInfo.status == runningStatus
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// Update global and (volume, path) stats.
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n.counters.lockRemoved(granted)
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volumePathLocks.counters.lockRemoved(granted)
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}
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delete(n.debugLockMap, param)
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return nil
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}
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// deleteLockInfoEntry - Deletes lock info entry for given opsID.
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// Called when the nsLk ref count for the given (volume, path) is
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// not 0.
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func (n *nsLockMap) deleteLockInfoEntryForOps(param nsParam, opsID string) error {
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// delete the lock info for the given operation.
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infoMap, found := n.debugLockMap[param]
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if !found {
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return traceError(LockInfoVolPathMissing{param.volume, param.path})
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}
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// The operation finished holding the lock on the resource, remove
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// the entry for the given operation with the operation ID.
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opsIDLock, foundInfo := infoMap.lockInfo[opsID]
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if !foundInfo {
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// Unlock request with invalid operation ID not accepted.
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return traceError(LockInfoOpsIDNotFound{param.volume, param.path, opsID})
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}
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// Update global and (volume, path) lock status.
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granted := opsIDLock.status == runningStatus
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n.counters.lockRemoved(granted)
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infoMap.counters.lockRemoved(granted)
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delete(infoMap.lockInfo, opsID)
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return nil
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}
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// Return randomly generated string ID
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func getOpsID() string {
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const opsIDLen = 16
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opsIDBytes := make([]byte, opsIDLen)
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if _, err := rand.Read(opsIDBytes); err != nil {
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panic(err)
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}
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for i := 0; i < opsIDLen; i++ {
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opsIDBytes[i] = alphaNumericTable[opsIDBytes[i]%alphaNumericTableLen]
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}
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return string(opsIDBytes)
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}
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