minio/cmd/lock-rest-server.go
Harshavardhana 2a79ea0332
isServerResolvable its sufficient to check server is reachable (#11609)
using isServerResolvable for expiration can lead to chicken
and egg problems, a lock might expire knowingly when server
is booting up causing perpetual locks getting expired.
2021-02-22 16:29:53 -08:00

400 lines
10 KiB
Go

/*
* Minio Cloud Storage, (C) 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 (
"bufio"
"context"
"errors"
"math/rand"
"net/http"
"sort"
"strconv"
"sync"
"time"
"github.com/gorilla/mux"
"github.com/minio/minio/pkg/dsync"
)
const (
// Lock maintenance interval.
lockMaintenanceInterval = 1 * time.Minute
// Lock validity check interval.
lockValidityCheckInterval = 30 * time.Second
)
// To abstract a node over network.
type lockRESTServer struct {
ll *localLocker
}
func (l *lockRESTServer) writeErrorResponse(w http.ResponseWriter, err error) {
w.WriteHeader(http.StatusForbidden)
w.Write([]byte(err.Error()))
}
// IsValid - To authenticate and verify the time difference.
func (l *lockRESTServer) IsValid(w http.ResponseWriter, r *http.Request) bool {
if l.ll == nil {
l.writeErrorResponse(w, errLockNotInitialized)
return false
}
if err := storageServerRequestValidate(r); err != nil {
l.writeErrorResponse(w, err)
return false
}
return true
}
func getLockArgs(r *http.Request) (args dsync.LockArgs, err error) {
quorum, err := strconv.Atoi(r.URL.Query().Get(lockRESTQuorum))
if err != nil {
return args, err
}
args = dsync.LockArgs{
Owner: r.URL.Query().Get(lockRESTOwner),
UID: r.URL.Query().Get(lockRESTUID),
Source: r.URL.Query().Get(lockRESTSource),
Quorum: quorum,
}
var resources []string
bio := bufio.NewScanner(r.Body)
for bio.Scan() {
resources = append(resources, bio.Text())
}
if err := bio.Err(); err != nil {
return args, err
}
sort.Strings(resources)
args.Resources = resources
return args, nil
}
// HealthHandler returns success if request is authenticated.
func (l *lockRESTServer) HealthHandler(w http.ResponseWriter, r *http.Request) {
l.IsValid(w, r)
}
// LockHandler - Acquires a lock.
func (l *lockRESTServer) LockHandler(w http.ResponseWriter, r *http.Request) {
if !l.IsValid(w, r) {
l.writeErrorResponse(w, errors.New("invalid request"))
return
}
args, err := getLockArgs(r)
if err != nil {
l.writeErrorResponse(w, err)
return
}
success, err := l.ll.Lock(r.Context(), args)
if err == nil && !success {
err = errLockConflict
}
if err != nil {
l.writeErrorResponse(w, err)
return
}
}
// UnlockHandler - releases the acquired lock.
func (l *lockRESTServer) UnlockHandler(w http.ResponseWriter, r *http.Request) {
if !l.IsValid(w, r) {
l.writeErrorResponse(w, errors.New("invalid request"))
return
}
args, err := getLockArgs(r)
if err != nil {
l.writeErrorResponse(w, err)
return
}
_, err = l.ll.Unlock(args)
// Ignore the Unlock() "reply" return value because if err == nil, "reply" is always true
// Consequently, if err != nil, reply is always false
if err != nil {
l.writeErrorResponse(w, err)
return
}
}
// LockHandler - Acquires an RLock.
func (l *lockRESTServer) RLockHandler(w http.ResponseWriter, r *http.Request) {
if !l.IsValid(w, r) {
l.writeErrorResponse(w, errors.New("invalid request"))
return
}
args, err := getLockArgs(r)
if err != nil {
l.writeErrorResponse(w, err)
return
}
success, err := l.ll.RLock(r.Context(), args)
if err == nil && !success {
err = errLockConflict
}
if err != nil {
l.writeErrorResponse(w, err)
return
}
}
// RUnlockHandler - releases the acquired read lock.
func (l *lockRESTServer) RUnlockHandler(w http.ResponseWriter, r *http.Request) {
if !l.IsValid(w, r) {
l.writeErrorResponse(w, errors.New("invalid request"))
return
}
args, err := getLockArgs(r)
if err != nil {
l.writeErrorResponse(w, err)
return
}
// Ignore the RUnlock() "reply" return value because if err == nil, "reply" is always true.
// Consequently, if err != nil, reply is always false
if _, err = l.ll.RUnlock(args); err != nil {
l.writeErrorResponse(w, err)
return
}
}
// ForceUnlockHandler - query expired lock status.
func (l *lockRESTServer) ForceUnlockHandler(w http.ResponseWriter, r *http.Request) {
if !l.IsValid(w, r) {
l.writeErrorResponse(w, errors.New("invalid request"))
return
}
args, err := getLockArgs(r)
if err != nil {
l.writeErrorResponse(w, err)
return
}
if _, err = l.ll.ForceUnlock(r.Context(), args); err != nil {
l.writeErrorResponse(w, err)
return
}
}
// ExpiredHandler - query expired lock status.
func (l *lockRESTServer) ExpiredHandler(w http.ResponseWriter, r *http.Request) {
if !l.IsValid(w, r) {
l.writeErrorResponse(w, errors.New("invalid request"))
return
}
args, err := getLockArgs(r)
if err != nil {
l.writeErrorResponse(w, err)
return
}
expired, err := l.ll.Expired(r.Context(), args)
if err != nil {
l.writeErrorResponse(w, err)
return
}
if !expired {
l.writeErrorResponse(w, errLockNotExpired)
return
}
}
// getLongLivedLocks returns locks that are older than a certain time and
// have not been 'checked' for validity too soon enough
func getLongLivedLocks(interval time.Duration) []lockRequesterInfo {
lrips := []lockRequesterInfo{}
globalLockServer.mutex.Lock()
for _, lriArray := range globalLockServer.lockMap {
for idx := range lriArray {
// Check whether enough time has gone by since last check
if time.Since(lriArray[idx].TimeLastCheck) >= interval {
lrips = append(lrips, lriArray[idx])
lriArray[idx].TimeLastCheck = UTCNow()
}
}
}
globalLockServer.mutex.Unlock()
return lrips
}
// lockMaintenance loops over locks that have been active for some time and checks back
// with the original server whether it is still alive or not
//
// Following logic inside ignores the errors generated for Dsync.Active operation.
// - server at client down
// - some network error (and server is up normally)
//
// We will ignore the error, and we will retry later to get a resolve on this lock
func lockMaintenance(ctx context.Context, interval time.Duration) {
objAPI := newObjectLayerFn()
if objAPI == nil {
return
}
z, ok := objAPI.(*erasureServerPools)
if !ok {
return
}
type nlock struct {
locks int
writer bool
}
updateNlocks := func(nlripsMap map[string]nlock, name string, writer bool) {
nlk, ok := nlripsMap[name]
if ok {
nlk.locks++
nlripsMap[name] = nlk
} else {
nlripsMap[name] = nlock{
locks: 1,
writer: writer,
}
}
}
// Validate if long lived locks are indeed clean.
// Get list of long lived locks to check for staleness.
lrips := getLongLivedLocks(interval)
lripsMap := make(map[string]nlock, len(lrips))
var mutex sync.Mutex // mutex for lripsMap updates
for _, lrip := range lrips {
// fetch the lockers participated in handing
// out locks for `nlrip.name`
var lockers []dsync.NetLocker
if lrip.Group {
lockers, _ = z.serverPools[0].getHashedSet("").getLockers()
} else {
_, objName := path2BucketObject(lrip.Name)
lockers, _ = z.serverPools[0].getHashedSet(objName).getLockers()
}
var wg sync.WaitGroup
wg.Add(len(lockers))
for _, c := range lockers {
go func(lrip lockRequesterInfo, c dsync.NetLocker) {
defer wg.Done()
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
// Call back to all participating servers, verify
// if each of those servers think lock is still
// active, if not expire it.
expired, err := c.Expired(ctx, dsync.LockArgs{
Owner: lrip.Owner,
UID: lrip.UID,
Resources: []string{lrip.Name},
})
cancel()
if err != nil {
mutex.Lock()
updateNlocks(lripsMap, lrip.Name, lrip.Writer)
mutex.Unlock()
return
}
if !expired {
mutex.Lock()
updateNlocks(lripsMap, lrip.Name, lrip.Writer)
mutex.Unlock()
}
}(lrip, c)
}
wg.Wait()
// less than the quorum, we have locks expired.
if lripsMap[lrip.Name].locks < lrip.Quorum {
// Purge the stale entry if it exists.
globalLockServer.removeEntryIfExists(lrip)
}
}
}
// Start lock maintenance from all lock servers.
func startLockMaintenance(ctx context.Context) {
// Wait until the object API is ready
// no need to start the lock maintenance
// if ObjectAPI is not initialized.
for {
objAPI := newObjectLayerFn()
if objAPI == nil {
time.Sleep(time.Second)
continue
}
break
}
// Initialize a new ticker with 1 minute between each ticks.
lkTimer := time.NewTimer(lockMaintenanceInterval)
// Stop the timer upon returning.
defer lkTimer.Stop()
r := rand.New(rand.NewSource(UTCNow().UnixNano()))
// Start with random sleep time, so as to avoid
// "synchronous checks" between servers
time.Sleep(time.Duration(r.Float64() * float64(lockMaintenanceInterval)))
for {
// Verifies every minute for locks held more than 2 minutes.
select {
case <-ctx.Done():
return
case <-lkTimer.C:
// Reset the timer for next cycle.
lkTimer.Reset(time.Duration(r.Float64() * float64(lockMaintenanceInterval)))
lockMaintenance(ctx, lockValidityCheckInterval)
}
}
}
// registerLockRESTHandlers - register lock rest router.
func registerLockRESTHandlers(router *mux.Router) {
lockServer := &lockRESTServer{
ll: newLocker(),
}
subrouter := router.PathPrefix(lockRESTPrefix).Subrouter()
subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodHealth).HandlerFunc(httpTraceHdrs(lockServer.HealthHandler))
subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodLock).HandlerFunc(httpTraceHdrs(lockServer.LockHandler))
subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodRLock).HandlerFunc(httpTraceHdrs(lockServer.RLockHandler))
subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodUnlock).HandlerFunc(httpTraceHdrs(lockServer.UnlockHandler))
subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodRUnlock).HandlerFunc(httpTraceHdrs(lockServer.RUnlockHandler))
subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodExpired).HandlerFunc(httpTraceAll(lockServer.ExpiredHandler))
subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodForceUnlock).HandlerFunc(httpTraceAll(lockServer.ForceUnlockHandler))
globalLockServer = lockServer.ll
go startLockMaintenance(GlobalContext)
}