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minio/cmd/lock-instrument.go

238 lines
7.6 KiB

/*
* Minio Cloud Storage, (C) 2016 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 (
"crypto/rand"
"fmt"
"time"
)
type statusType string
const (
runningStatus statusType = "Running"
blockedStatus statusType = "Blocked"
)
type lockType string
const (
debugRLockStr lockType = "RLock"
debugWLockStr lockType = "WLock"
)
// debugLockInfo - represents a single lock's information, uniquely identified by opsID.
// See debugLockInfoPerVolumePath for more context.
type debugLockInfo struct {
// "RLock" or "WLock".
lType lockType
// Contains the backtrace of incl. the function which called (r)(un)lock.
lockSource string
// Status can be running/blocked.
status statusType
// Time of last status update.
since time.Time
}
// debugLockInfoPerVolumePath - lock state information on all locks held on (volume, path).
type debugLockInfoPerVolumePath struct {
counters *lockStat // Holds stats of lock held on (volume, path)
lockInfo map[string]debugLockInfo // Lock information per operation ID.
}
// LockInfoOriginMismatch - represents error when lock origin don't match.
type LockInfoOriginMismatch struct {
volume string
path string
opsID string
lockSource string
}
func (l LockInfoOriginMismatch) Error() string {
return fmt.Sprintf("No lock state stored for the lock originated at \"%s\", for <volume> %s, <path> %s, <opsID> %s",
l.lockSource, l.volume, l.path, l.opsID)
}
// LockInfoVolPathMissing - represents error when lock information is missing for a given (volume, path).
type LockInfoVolPathMissing struct {
volume string
path string
}
func (l LockInfoVolPathMissing) Error() string {
return fmt.Sprintf("No entry in debug Lock Map for Volume: %s, path: %s", l.volume, l.path)
}
// LockInfoOpsIDNotFound - represents error when lock info entry for a given operation ID doesn't exist.
type LockInfoOpsIDNotFound struct {
volume string
path string
opsID string
}
func (l LockInfoOpsIDNotFound) Error() string {
return fmt.Sprintf("No entry in lock info for <Operation ID> %s, <volume> %s, <path> %s", l.opsID, l.volume, l.path)
}
// LockInfoStateNotBlocked - represents error when lock info isn't in blocked state when it should be.
type LockInfoStateNotBlocked struct {
volume string
path string
opsID string
}
func (l LockInfoStateNotBlocked) Error() string {
return fmt.Sprintf("Lock state should be \"Blocked\" for <volume> %s, <path> %s, <opsID> %s", l.volume, l.path, l.opsID)
}
// Initialize lock info for given (volume, path).
func (n *nsLockMap) initLockInfoForVolumePath(param nsParam) {
n.debugLockMap[param] = &debugLockInfoPerVolumePath{
lockInfo: make(map[string]debugLockInfo),
counters: &lockStat{},
}
}
// Change the state of the lock from Blocked to Running.
func (n *nsLockMap) statusBlockedToRunning(param nsParam, lockSource, opsID string, readLock bool) error {
// This function is called outside nsLockMap.mutex.Lock(), so must be held explicitly.
n.lockMapMutex.Lock()
defer n.lockMapMutex.Unlock()
// Check whether the lock info entry for <volume, path> pair already exists.
_, ok := n.debugLockMap[param]
if !ok {
return traceError(LockInfoVolPathMissing{param.volume, param.path})
}
// Check whether lock info entry for the given `opsID` exists.
lockInfo, ok := n.debugLockMap[param].lockInfo[opsID]
if !ok {
return traceError(LockInfoOpsIDNotFound{param.volume, param.path, opsID})
}
// Check whether lockSource is same.
if lockInfo.lockSource != lockSource {
return traceError(LockInfoOriginMismatch{param.volume, param.path, opsID, lockSource})
}
// Status of the lock should be set to "Blocked".
if lockInfo.status != blockedStatus {
return traceError(LockInfoStateNotBlocked{param.volume, param.path, opsID})
}
// Change lock status to running and update the time.
n.debugLockMap[param].lockInfo[opsID] = newDebugLockInfo(lockSource, runningStatus, readLock)
// Update global lock stats.
n.counters.lockGranted()
// Update (volume, pair) lock stats.
n.debugLockMap[param].counters.lockGranted()
return nil
}
// newDebugLockInfo - Constructs a debugLockInfo value given lock source, status and type.
func newDebugLockInfo(lockSource string, status statusType, readLock bool) debugLockInfo {
var lType lockType
if readLock {
lType = debugRLockStr
} else {
lType = debugWLockStr
}
return debugLockInfo{
lockSource: lockSource,
lType: lType,
status: status,
since: time.Now().UTC(),
}
}
// Change the state of the lock to Blocked.
func (n *nsLockMap) statusNoneToBlocked(param nsParam, lockSource, opsID string, readLock bool) error {
_, ok := n.debugLockMap[param]
if !ok {
// Lock info entry for (volume, pair) doesn't exist, initialize it.
n.initLockInfoForVolumePath(param)
}
// Mark lock status blocked for given opsID.
n.debugLockMap[param].lockInfo[opsID] = newDebugLockInfo(lockSource, blockedStatus, readLock)
// Update global lock stats.
n.counters.lockWaiting()
// Update (volume, path) lock stats.
n.debugLockMap[param].counters.lockWaiting()
return nil
}
// deleteLockInfoEntry - Deletes the lock information for given (volume, path).
// Called when nsLk.ref count is 0.
func (n *nsLockMap) deleteLockInfoEntryForVolumePath(param nsParam) error {
// delete the lock info for the given operation.
if _, found := n.debugLockMap[param]; !found {
return traceError(LockInfoVolPathMissing{param.volume, param.path})
}
// The following stats update is relevant only in case of a
// ForceUnlock. In case of the last unlock on a (volume,
// path), this would be a no-op.
volumePathLocks := n.debugLockMap[param]
for _, lockInfo := range volumePathLocks.lockInfo {
granted := lockInfo.status == runningStatus
// Update global and (volume, path) stats.
n.counters.lockRemoved(granted)
volumePathLocks.counters.lockRemoved(granted)
}
delete(n.debugLockMap, param)
return nil
}
// deleteLockInfoEntry - Deletes lock info entry for given opsID.
// Called when the nsLk ref count for the given (volume, path) is
// not 0.
func (n *nsLockMap) deleteLockInfoEntryForOps(param nsParam, opsID string) error {
// delete the lock info for the given operation.
infoMap, found := n.debugLockMap[param]
if !found {
return traceError(LockInfoVolPathMissing{param.volume, param.path})
}
// The operation finished holding the lock on the resource, remove
// the entry for the given operation with the operation ID.
opsIDLock, foundInfo := infoMap.lockInfo[opsID]
if !foundInfo {
// Unlock request with invalid operation ID not accepted.
return traceError(LockInfoOpsIDNotFound{param.volume, param.path, opsID})
}
// Update global and (volume, path) lock status.
granted := opsIDLock.status == runningStatus
n.counters.lockRemoved(granted)
infoMap.counters.lockRemoved(granted)
delete(infoMap.lockInfo, opsID)
return nil
}
// Return randomly generated string ID
func getOpsID() string {
const opsIDLen = 16
opsIDBytes := make([]byte, opsIDLen)
if _, err := rand.Read(opsIDBytes); err != nil {
panic(err)
}
for i := 0; i < opsIDLen; i++ {
opsIDBytes[i] = alphaNumericTable[opsIDBytes[i]%alphaNumericTableLen]
}
return string(opsIDBytes)
}