minio/cmd/retry-storage.go

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/*
* 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 (
"time"
"github.com/minio/minio/pkg/disk"
)
const (
// Attempt to retry only this many number of times before
// giving up on the remote disk entirely during initialization.
globalStorageInitRetryThreshold = 4
// Attempt to retry only this many number of times before
// giving up on the remote disk entirely after initialization.
globalStorageRetryThreshold = 1
// Interval to check health status of a node whether it has
// come back up online
globalStorageHealthCheckInterval = 5 * time.Minute
)
// Converts rpc.ServerError to underlying error. This function is
// written so that the storageAPI errors are consistent across network
// disks as well.
func retryToStorageErr(err error) error {
if err == errDiskNotFoundFromNetError || err == errDiskNotFoundFromRPCShutdown {
return errDiskNotFound
}
return err
}
// Retry storage is an instance of StorageAPI which
// additionally verifies upon network shutdown if the
// underlying storage is available and is really
// formatted. After the initialization phase it will
// also cache when the underlying storage is offline
// to prevent needless calls and recheck the health of
// underlying storage in regular intervals.
type retryStorage struct {
remoteStorage StorageAPI
maxRetryAttempts int
retryUnit time.Duration
retryCap time.Duration
offline bool // Mark whether node is offline
offlineTimestamp time.Time // Last timestamp of checking status of node
}
// String representation of remoteStorage.
func (f *retryStorage) String() string {
return f.remoteStorage.String()
}
// Reconnects to underlying remote storage.
func (f *retryStorage) Init() (err error) {
return retryToStorageErr(f.remoteStorage.Init())
}
// Closes the underlying remote storage connection.
func (f *retryStorage) Close() (err error) {
return retryToStorageErr(f.remoteStorage.Close())
}
// Return whether the underlying remote storage is offline
// and, if so, try to reconnect at regular intervals to
// restore the connection
func (f *retryStorage) IsOffline() bool {
// Check if offline and whether enough time has lapsed since most recent check
if f.offline && UTCNow().Sub(f.offlineTimestamp) >= globalStorageHealthCheckInterval {
f.offlineTimestamp = UTCNow() // reset timestamp
if e := f.reInit(nil); e == nil {
// Connection has been re-established
f.offline = false // Mark node as back online
}
}
return f.offline
}
// DiskInfo - a retryable implementation of disk info.
func (f *retryStorage) DiskInfo() (info disk.Info, err error) {
if f.IsOffline() {
return info, errDiskNotFound
}
info, err = f.remoteStorage.DiskInfo()
if f.reInitUponDiskNotFound(err) {
info, err = f.remoteStorage.DiskInfo()
return info, retryToStorageErr(err)
}
return info, retryToStorageErr(err)
}
// MakeVol - a retryable implementation of creating a volume.
func (f *retryStorage) MakeVol(volume string) (err error) {
if f.IsOffline() {
return errDiskNotFound
}
err = f.remoteStorage.MakeVol(volume)
if f.reInitUponDiskNotFound(err) {
return retryToStorageErr(f.remoteStorage.MakeVol(volume))
}
return retryToStorageErr(err)
}
// ListVols - a retryable implementation of listing all the volumes.
func (f *retryStorage) ListVols() (vols []VolInfo, err error) {
if f.IsOffline() {
return vols, errDiskNotFound
}
vols, err = f.remoteStorage.ListVols()
if f.reInitUponDiskNotFound(err) {
vols, err = f.remoteStorage.ListVols()
return vols, retryToStorageErr(err)
}
return vols, retryToStorageErr(err)
}
// StatVol - a retryable implementation of stating a volume.
func (f *retryStorage) StatVol(volume string) (vol VolInfo, err error) {
if f.IsOffline() {
return vol, errDiskNotFound
}
vol, err = f.remoteStorage.StatVol(volume)
if f.reInitUponDiskNotFound(err) {
vol, err = f.remoteStorage.StatVol(volume)
return vol, retryToStorageErr(err)
}
return vol, retryToStorageErr(err)
}
// DeleteVol - a retryable implementation of deleting a volume.
func (f *retryStorage) DeleteVol(volume string) (err error) {
if f.IsOffline() {
return errDiskNotFound
}
err = f.remoteStorage.DeleteVol(volume)
if f.reInitUponDiskNotFound(err) {
return retryToStorageErr(f.remoteStorage.DeleteVol(volume))
}
return retryToStorageErr(err)
}
// PrepareFile - a retryable implementation of preparing a file.
func (f *retryStorage) PrepareFile(volume, path string, length int64) (err error) {
if f.IsOffline() {
return errDiskNotFound
}
err = f.remoteStorage.PrepareFile(volume, path, length)
if f.reInitUponDiskNotFound(err) {
return retryToStorageErr(f.remoteStorage.PrepareFile(volume, path, length))
}
return retryToStorageErr(err)
}
// AppendFile - a retryable implementation of append to a file.
func (f *retryStorage) AppendFile(volume, path string, buffer []byte) (err error) {
if f.IsOffline() {
return errDiskNotFound
}
err = f.remoteStorage.AppendFile(volume, path, buffer)
if f.reInitUponDiskNotFound(err) {
return retryToStorageErr(f.remoteStorage.AppendFile(volume, path, buffer))
}
return retryToStorageErr(err)
}
// StatFile - a retryable implementation of stating a file.
func (f *retryStorage) StatFile(volume, path string) (fileInfo FileInfo, err error) {
if f.IsOffline() {
return fileInfo, errDiskNotFound
}
fileInfo, err = f.remoteStorage.StatFile(volume, path)
if f.reInitUponDiskNotFound(err) {
fileInfo, err = f.remoteStorage.StatFile(volume, path)
return fileInfo, retryToStorageErr(err)
}
return fileInfo, retryToStorageErr(err)
}
// ReadAll - a retryable implementation of reading all the content from a file.
func (f *retryStorage) ReadAll(volume, path string) (buf []byte, err error) {
if f.IsOffline() {
return buf, errDiskNotFound
}
buf, err = f.remoteStorage.ReadAll(volume, path)
if f.reInitUponDiskNotFound(err) {
buf, err = f.remoteStorage.ReadAll(volume, path)
return buf, retryToStorageErr(err)
}
return buf, retryToStorageErr(err)
}
// ReadFile - a retryable implementation of reading at offset from a file.
func (f *retryStorage) ReadFile(volume, path string, offset int64, buffer []byte, verifier *BitrotVerifier) (m int64, err error) {
if f.IsOffline() {
return m, errDiskNotFound
}
m, err = f.remoteStorage.ReadFile(volume, path, offset, buffer, verifier)
if f.reInitUponDiskNotFound(err) {
m, err = f.remoteStorage.ReadFile(volume, path, offset, buffer, verifier)
return m, retryToStorageErr(err)
}
return m, retryToStorageErr(err)
}
// ListDir - a retryable implementation of listing directory entries.
func (f *retryStorage) ListDir(volume, path string) (entries []string, err error) {
if f.IsOffline() {
return entries, errDiskNotFound
}
entries, err = f.remoteStorage.ListDir(volume, path)
if f.reInitUponDiskNotFound(err) {
entries, err = f.remoteStorage.ListDir(volume, path)
return entries, retryToStorageErr(err)
}
return entries, retryToStorageErr(err)
}
// DeleteFile - a retryable implementation of deleting a file.
func (f *retryStorage) DeleteFile(volume, path string) (err error) {
if f.IsOffline() {
return errDiskNotFound
}
err = f.remoteStorage.DeleteFile(volume, path)
if f.reInitUponDiskNotFound(err) {
return retryToStorageErr(f.remoteStorage.DeleteFile(volume, path))
}
return retryToStorageErr(err)
}
// RenameFile - a retryable implementation of renaming a file.
func (f *retryStorage) RenameFile(srcVolume, srcPath, dstVolume, dstPath string) (err error) {
if f.IsOffline() {
return errDiskNotFound
}
err = f.remoteStorage.RenameFile(srcVolume, srcPath, dstVolume, dstPath)
if f.reInitUponDiskNotFound(err) {
return retryToStorageErr(f.remoteStorage.RenameFile(srcVolume, srcPath, dstVolume, dstPath))
}
return retryToStorageErr(err)
}
// Try to reinitialize the connection when we have some form of DiskNotFound error
func (f *retryStorage) reInitUponDiskNotFound(err error) bool {
if err == errDiskNotFound || err == errDiskNotFoundFromNetError || err == errDiskNotFoundFromRPCShutdown {
return f.reInit(err) == nil
}
return false
}
// Connect and attempt to load the format from a disconnected node,
// attempts three times before giving up.
func (f *retryStorage) reInit(e error) (err error) {
// Only after initialization and minimum of one interval
// has passed (to prevent marking a node as offline right
// after initialization), check whether node has gone offline
if f.maxRetryAttempts == globalStorageRetryThreshold &&
UTCNow().Sub(f.offlineTimestamp) >= globalStorageHealthCheckInterval {
if e == errDiskNotFoundFromNetError { // Make node offline due to network error
f.offline = true // Marking node offline
f.offlineTimestamp = UTCNow()
return errDiskNotFound
}
// Continue for other errors like RPC shutdown (and retry connection below)
}
// Close the underlying connection.
f.remoteStorage.Close() // Error here is purposefully ignored.
// Done channel is used to close any lingering retry routine, as soon
// as this function returns.
doneCh := make(chan struct{})
defer close(doneCh)
for i := range newRetryTimer(f.retryUnit, f.retryCap, doneCh) {
// Initialize and make a new login attempt.
err = f.remoteStorage.Init()
if err != nil {
// No need to return error until the retry count
// threshold has reached.
if i < f.maxRetryAttempts {
continue
}
return err
}
// Attempt to load format to see if the disk is really
// a formatted disk and part of the cluster.
_, err = loadFormat(f.remoteStorage)
if err != nil {
// No need to return error until the retry count
// threshold has reached.
if i < f.maxRetryAttempts {
continue
}
return err
}
// Login and loading format was a success, break and proceed forward.
break
}
return err
}