284 lines
8.4 KiB
Go
284 lines
8.4 KiB
Go
/*
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* Minio Cloud Storage, (C) 2019 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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"errors"
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"math/rand"
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"net/http"
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"path"
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"time"
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"github.com/gorilla/mux"
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"github.com/minio/minio/pkg/dsync"
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)
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const (
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// Lock maintenance interval.
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lockMaintenanceInterval = 30 * time.Second
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// Lock validity check interval.
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lockValidityCheckInterval = 2 * time.Minute
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)
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// To abstract a node over network.
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type lockRESTServer struct {
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ll *localLocker
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}
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func (l *lockRESTServer) writeErrorResponse(w http.ResponseWriter, err error) {
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w.WriteHeader(http.StatusForbidden)
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w.Write([]byte(err.Error()))
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}
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// IsValid - To authenticate and verify the time difference.
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func (l *lockRESTServer) IsValid(w http.ResponseWriter, r *http.Request) bool {
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if err := storageServerRequestValidate(r); err != nil {
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l.writeErrorResponse(w, err)
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return false
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}
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return true
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}
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func getLockArgs(r *http.Request) dsync.LockArgs {
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return dsync.LockArgs{
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UID: r.URL.Query().Get(lockRESTUID),
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Source: r.URL.Query().Get(lockRESTSource),
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Resource: r.URL.Query().Get(lockRESTResource),
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}
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}
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// LockHandler - Acquires a lock.
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func (l *lockRESTServer) LockHandler(w http.ResponseWriter, r *http.Request) {
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if !l.IsValid(w, r) {
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l.writeErrorResponse(w, errors.New("Invalid request"))
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return
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}
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success, err := l.ll.Lock(getLockArgs(r))
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if err == nil && !success {
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err = errLockConflict
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}
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if err != nil {
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l.writeErrorResponse(w, err)
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return
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}
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}
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// UnlockHandler - releases the acquired lock.
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func (l *lockRESTServer) UnlockHandler(w http.ResponseWriter, r *http.Request) {
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if !l.IsValid(w, r) {
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l.writeErrorResponse(w, errors.New("Invalid request"))
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return
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}
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_, err := l.ll.Unlock(getLockArgs(r))
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// Ignore the Unlock() "reply" return value because if err == nil, "reply" is always true
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// Consequently, if err != nil, reply is always false
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if err != nil {
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l.writeErrorResponse(w, err)
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return
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}
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}
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// LockHandler - Acquires an RLock.
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func (l *lockRESTServer) RLockHandler(w http.ResponseWriter, r *http.Request) {
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if !l.IsValid(w, r) {
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l.writeErrorResponse(w, errors.New("Invalid request"))
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return
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}
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success, err := l.ll.RLock(getLockArgs(r))
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if err == nil && !success {
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err = errLockConflict
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}
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if err != nil {
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l.writeErrorResponse(w, err)
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return
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}
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}
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// RUnlockHandler - releases the acquired read lock.
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func (l *lockRESTServer) RUnlockHandler(w http.ResponseWriter, r *http.Request) {
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if !l.IsValid(w, r) {
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l.writeErrorResponse(w, errors.New("Invalid request"))
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return
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}
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// Ignore the RUnlock() "reply" return value because if err == nil, "reply" is always true.
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// Consequently, if err != nil, reply is always false
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_, err := l.ll.RUnlock(getLockArgs(r))
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if err != nil {
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l.writeErrorResponse(w, err)
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return
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}
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}
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// ExpiredHandler - query expired lock status.
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func (l *lockRESTServer) ExpiredHandler(w http.ResponseWriter, r *http.Request) {
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if !l.IsValid(w, r) {
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l.writeErrorResponse(w, errors.New("Invalid request"))
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return
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}
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lockArgs := getLockArgs(r)
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l.ll.mutex.Lock()
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defer l.ll.mutex.Unlock()
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// Lock found, proceed to verify if belongs to given uid.
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if lri, ok := l.ll.lockMap[lockArgs.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 == lockArgs.UID {
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l.writeErrorResponse(w, errLockNotExpired)
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return
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}
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}
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}
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}
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// nameLockRequesterInfoPair is a helper type for lock maintenance
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type nameLockRequesterInfoPair struct {
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name string
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lri lockRequesterInfo
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}
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// getLongLivedLocks returns locks that are older than a certain time and
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// have not been 'checked' for validity too soon enough
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func getLongLivedLocks(interval time.Duration) map[Endpoint][]nameLockRequesterInfoPair {
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nlripMap := make(map[Endpoint][]nameLockRequesterInfoPair)
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for endpoint, locker := range globalLockServers {
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rslt := []nameLockRequesterInfoPair{}
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locker.mutex.Lock()
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for name, lriArray := range locker.lockMap {
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for idx := range lriArray {
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// Check whether enough time has gone by since last check
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if time.Since(lriArray[idx].TimeLastCheck) >= interval {
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rslt = append(rslt, nameLockRequesterInfoPair{name: name, lri: lriArray[idx]})
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lriArray[idx].TimeLastCheck = UTCNow()
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}
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}
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}
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nlripMap[endpoint] = rslt
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locker.mutex.Unlock()
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}
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return nlripMap
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}
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// lockMaintenance loops over locks that have been active for some time and checks back
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// with the original server whether it is still alive or not
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//
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// Following logic inside ignores the errors generated for Dsync.Active operation.
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// - server at client down
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// - some network error (and server is up normally)
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//
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// We will ignore the error, and we will retry later to get a resolve on this lock
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func lockMaintenance(interval time.Duration) {
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// Validate if long lived locks are indeed clean.
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// Get list of long lived locks to check for staleness.
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for lendpoint, nlrips := range getLongLivedLocks(interval) {
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for _, nlrip := range nlrips {
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for _, ep := range globalEndpoints {
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for _, endpoint := range ep.Endpoints {
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if endpoint.String() == lendpoint.String() {
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continue
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}
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c := newLockAPI(endpoint)
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if !c.IsOnline() {
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continue
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}
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// Call back to original server verify whether the lock is still active (based on name & uid)
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expired, err := c.Expired(dsync.LockArgs{
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UID: nlrip.lri.UID,
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Resource: nlrip.name,
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})
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if err != nil {
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c.Close()
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continue
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}
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// For successful response, verify if lock was indeed active or stale.
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if expired {
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// The lock is no longer active at server that originated
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// the lock, attempt to remove the lock.
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globalLockServers[lendpoint].mutex.Lock()
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// Purge the stale entry if it exists.
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globalLockServers[lendpoint].removeEntryIfExists(nlrip)
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globalLockServers[lendpoint].mutex.Unlock()
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}
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// Close the connection regardless of the call response.
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c.Close()
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}
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}
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}
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}
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}
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// Start lock maintenance from all lock servers.
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func startLockMaintenance() {
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// Initialize a new ticker with a minute between each ticks.
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ticker := time.NewTicker(lockMaintenanceInterval)
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// Stop the timer upon service closure and cleanup the go-routine.
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defer ticker.Stop()
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for {
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// Verifies every minute for locks held more than 2 minutes.
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select {
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case <-GlobalServiceDoneCh:
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return
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case <-ticker.C:
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// Start with random sleep time, so as to avoid
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// "synchronous checks" between servers
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r := rand.New(rand.NewSource(UTCNow().UnixNano()))
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duration := time.Duration(r.Float64() * float64(lockMaintenanceInterval))
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time.Sleep(duration)
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lockMaintenance(lockValidityCheckInterval)
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}
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}
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}
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// registerLockRESTHandlers - register lock rest router.
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func registerLockRESTHandlers(router *mux.Router, endpointZones EndpointZones) {
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queries := restQueries(lockRESTUID, lockRESTSource, lockRESTResource)
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for _, ep := range endpointZones {
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for _, endpoint := range ep.Endpoints {
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if !endpoint.IsLocal {
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continue
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}
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lockServer := &lockRESTServer{
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ll: newLocker(endpoint),
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}
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subrouter := router.PathPrefix(path.Join(lockRESTPrefix, endpoint.Path)).Subrouter()
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subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodLock).HandlerFunc(httpTraceHdrs(lockServer.LockHandler)).Queries(queries...)
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subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodRLock).HandlerFunc(httpTraceHdrs(lockServer.RLockHandler)).Queries(queries...)
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subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodUnlock).HandlerFunc(httpTraceHdrs(lockServer.UnlockHandler)).Queries(queries...)
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subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodRUnlock).HandlerFunc(httpTraceHdrs(lockServer.RUnlockHandler)).Queries(queries...)
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subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodExpired).HandlerFunc(httpTraceAll(lockServer.ExpiredHandler)).Queries(queries...)
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globalLockServers[endpoint] = lockServer.ll
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}
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}
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go startLockMaintenance()
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}
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