273 lines
10 KiB
Go
273 lines
10 KiB
Go
/*
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* Minio Cloud Storage, (C) 2016 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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"fmt"
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"time"
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)
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const (
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debugRLockStr = "RLock"
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debugWLockStr = "WLock"
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)
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// struct containing information of status (ready/running/blocked) of an operation with given operation ID.
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type debugLockInfo struct {
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lockType string // "Rlock" or "WLock".
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lockOrigin string // contains the trace of the function which invoked the lock, obtained from runtime.
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status string // status can be running/ready/blocked.
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since time.Time // time info of the since how long the status holds true.
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}
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// debugLockInfo - container for storing locking information for unique copy (volume,path) pair.
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// ref variable holds the reference count for locks held for.
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// `ref` values helps us understand the n locks held for given <volume, path> pair.
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// `running` value helps us understand the total successful locks held (not blocked) for given <volume, path> pair and the operation is under execution.
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// `blocked` value helps us understand the total number of operations blocked waiting on locks for given <volume,path> pair.
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type debugLockInfoPerVolumePath struct {
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ref int64 // running + blocked operations.
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running int64 // count of successful lock acquire and running operations.
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blocked int64 // count of number of operations blocked waiting on lock.
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lockInfo (map[string]debugLockInfo) // map of [operationID] debugLockInfo{operation, status, since} .
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}
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// returns an instance of debugLockInfo.
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// need to create this for every unique pair of {volume,path}.
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// total locks, number of calls blocked on locks, and number of successful locks held but not unlocked yet.
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func newDebugLockInfoPerVolumePath() *debugLockInfoPerVolumePath {
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return &debugLockInfoPerVolumePath{
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lockInfo: make(map[string]debugLockInfo),
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ref: 0,
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blocked: 0,
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running: 0,
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}
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}
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// LockInfoOriginNotFound - While changing the state of the lock info its important that the entry for
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// lock at a given origin exists, if not `LockInfoOriginNotFound` is returned.
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type LockInfoOriginNotFound struct {
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volume string
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path string
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operationID string
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lockOrigin string
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}
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func (l LockInfoOriginNotFound) Error() string {
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return fmt.Sprintf("No lock state stored for the lock origined at \"%s\", for <volume> %s, <path> %s, <operationID> %s.",
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l.lockOrigin, l.volume, l.path, l.operationID)
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}
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// LockInfoVolPathMssing - Error interface. Returned when the info the
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type LockInfoVolPathMssing struct {
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volume string
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path string
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}
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func (l LockInfoVolPathMssing) 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 - Returned when the lock state info exists, but the entry for
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// 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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operationID 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.operationID, l.volume, l.path)
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}
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// LockInfoStateNotBlocked - When an attempt to change the state of the lock form `blocked` to `running` is done,
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// its necessary that the state before the transsition is "blocked", otherwise LockInfoStateNotBlocked returned.
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type LockInfoStateNotBlocked struct {
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volume string
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path string
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operationID 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, <operationID> %s.", l.volume, l.path, l.operationID)
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}
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var errLockNotInitialized = errors.New("Debug Lock Map not initialized:\n1. Enable Lock Debugging using right ENV settings \n2. Make sure initNSLock() is called.")
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// change the state of the lock from Blocked to Running.
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func (n *nsLockMap) statusBlockedToRunning(param nsParam, lockOrigin, operationID string, readLock bool) error {
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// This operation is not executed under the scope nsLockMap.mutex.Lock(), lock has to be explicitly held here.
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n.lockMapMutex.Lock()
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defer n.lockMapMutex.Unlock()
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if n.debugLockMap == nil {
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return errLockNotInitialized
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}
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// new state info to be set for the lock.
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newLockInfo := debugLockInfo{
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lockOrigin: lockOrigin,
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status: "Running",
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since: time.Now().UTC(),
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}
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// set lock type.
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if readLock {
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newLockInfo.lockType = debugRLockStr
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} else {
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newLockInfo.lockType = debugWLockStr
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}
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// check whether the lock info entry for <volume, path> pair already exists and its not `nil`.
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if debugLockMap, ok := n.debugLockMap[param]; ok {
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// ``*debugLockInfoPerVolumePath` entry containing lock info for `param <volume, path>` is `nil`.
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if debugLockMap == nil {
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return errLockNotInitialized
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}
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} else {
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// The lock state info foe given <volume, path> pair should already exist.
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// If not return `LockInfoVolPathMssing`.
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return LockInfoVolPathMssing{param.volume, param.path}
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}
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// Lock info the for the given operation ID shouldn't be `nil`.
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if n.debugLockMap[param].lockInfo == nil {
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return LockInfoOpsIDNotFound{param.volume, param.path, operationID}
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}
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if lockInfo, ok := n.debugLockMap[param].lockInfo[operationID]; ok {
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// The entry for the lock origined at `lockOrigin` should already exist.
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// If not return `LockInfoOriginNotFound`.
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if lockInfo.lockOrigin != lockOrigin {
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return LockInfoOriginNotFound{param.volume, param.path, operationID, lockOrigin}
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}
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// Status of the lock should already be set to "Blocked".
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// If not return `LockInfoStateNotBlocked`.
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if lockInfo.status != "Blocked" {
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return LockInfoStateNotBlocked{param.volume, param.path, operationID}
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}
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} else {
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// The lock info entry for given `opsID` should already exist for given <volume, path> pair.
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// If not return `LockInfoOpsIDNotFound`.
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return LockInfoOpsIDNotFound{param.volume, param.path, operationID}
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}
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// All checks finished.
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// changing the status of the operation from blocked to running and updating the time.
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n.debugLockMap[param].lockInfo[operationID] = newLockInfo
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// After locking unblocks decrease the blocked counter.
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n.blockedCounter--
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// Increase the running counter.
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n.runningLockCounter++
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n.debugLockMap[param].blocked--
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n.debugLockMap[param].running++
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return nil
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}
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// change the state of the lock from Ready to Blocked.
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func (n *nsLockMap) statusNoneToBlocked(param nsParam, lockOrigin, operationID string, readLock bool) error {
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if n.debugLockMap == nil {
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return errLockNotInitialized
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}
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newLockInfo := debugLockInfo{
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lockOrigin: lockOrigin,
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status: "Blocked",
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since: time.Now().UTC(),
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}
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if readLock {
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newLockInfo.lockType = debugRLockStr
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} else {
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newLockInfo.lockType = debugWLockStr
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}
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if lockInfo, ok := n.debugLockMap[param]; ok {
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if lockInfo == nil {
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// *debugLockInfoPerVolumePath entry is nil, initialize here to avoid any case of `nil` pointer access.
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n.initLockInfoForVolumePath(param)
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}
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} else {
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// State info entry for the given <volume, pair> doesn't exist, initializing it.
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n.initLockInfoForVolumePath(param)
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}
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// lockInfo is a map[string]debugLockInfo, which holds map[OperationID]{status,time, origin} of the lock.
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if n.debugLockMap[param].lockInfo == nil {
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n.debugLockMap[param].lockInfo = make(map[string]debugLockInfo)
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}
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// The status of the operation with the given operation ID is marked blocked till its gets unblocked from the lock.
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n.debugLockMap[param].lockInfo[operationID] = newLockInfo
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// Increment the Global lock counter.
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n.globalLockCounter++
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// Increment the counter for number of blocked opertions, decrement it after the locking unblocks.
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n.blockedCounter++
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// increment the reference of the lock for the given <volume,path> pair.
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n.debugLockMap[param].ref++
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// increment the blocked counter for the given <volume, path> pair.
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n.debugLockMap[param].blocked++
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return nil
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}
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// deleteLockInfoEntry - Deletes the lock state information for given <volume, path> pair. Called when nsLk.ref count is 0.
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func (n *nsLockMap) deleteLockInfoEntryForVolumePath(param nsParam) error {
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if n.debugLockMap == nil {
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return errLockNotInitialized
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}
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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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// Remove from the map if there are no more references for the given (volume,path) pair.
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delete(n.debugLockMap, param)
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} else {
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return LockInfoVolPathMssing{param.volume, param.path}
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}
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return nil
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}
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// deleteLockInfoEntry - Deletes the entry for given opsID in the lock state information of given <volume, path> pair.
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// called when the nsLk ref count for the given <volume, path> pair is not 0.
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func (n *nsLockMap) deleteLockInfoEntryForOps(param nsParam, operationID string) error {
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if n.debugLockMap == nil {
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return errLockNotInitialized
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}
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// delete the lock info for the given operation.
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if infoMap, found := n.debugLockMap[param]; found {
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// the opertion finished holding the lock on the resource, remove the entry for the given operation with the operation ID.
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if _, foundInfo := infoMap.lockInfo[operationID]; foundInfo {
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// decrease the global running and lock reference counter.
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n.runningLockCounter--
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n.globalLockCounter--
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// decrease the lock referee counter for the lock info for given <volume,path> pair.
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// decrease the running operation number. Its assumed that the operation is over once an attempt to release the lock is made.
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infoMap.running--
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// decrease the total reference count of locks jeld on <volume,path> pair.
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infoMap.ref--
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delete(infoMap.lockInfo, operationID)
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} else {
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// Unlock request with invalid opertion ID not accepted.
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return LockInfoOpsIDNotFound{param.volume, param.path, operationID}
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}
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} else {
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return LockInfoVolPathMssing{param.volume, param.path}
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}
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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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return string(generateRequestID())
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}
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