minio/tree-walk.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 main
import (
"os"
"path"
"sort"
"strings"
"sync"
"time"
)
// listParams - list object params used for list object map
type listParams struct {
bucket string
recursive bool
marker string
prefix string
}
// Tree walk result carries results of tree walking.
type treeWalkResult struct {
fileInfo FileInfo
err error
end bool
}
// Tree walk notify carries a channel which notifies tree walk
// results, additionally it also carries information if treeWalk
// should be timedOut.
type treeWalker struct {
ch <-chan treeWalkResult
timedOut bool
}
// treeWalk walks FS directory tree recursively pushing fileInfo into the channel as and when it encounters files.
func treeWalk(layer ObjectLayer, bucket, prefixDir, entryPrefixMatch, marker string, recursive bool, send func(treeWalkResult) bool, count *int) bool {
// Example:
// if prefixDir="one/two/three/" and marker="four/five.txt" treeWalk is recursively
// called with prefixDir="one/two/three/four/" and marker="five.txt"
var isXL bool
var disk StorageAPI
switch l := layer.(type) {
case xlObjects:
isXL = true
disk = l.storage
case fsObjects:
disk = l.storage
}
// Convert entry to FileInfo
entryToFileInfo := func(entry string) (fileInfo FileInfo, err error) {
if strings.HasSuffix(entry, slashSeparator) {
// Object name needs to be full path.
fileInfo.Name = path.Join(prefixDir, entry)
fileInfo.Name += slashSeparator
fileInfo.Mode = os.ModeDir
return
}
if isXL && strings.HasSuffix(entry, multipartSuffix) {
// If the entry was detected as a multipart file we use
// getMultipartObjectInfo() to fill the FileInfo structure.
entry = strings.TrimSuffix(entry, multipartSuffix)
var info MultipartObjectInfo
info, err = getMultipartObjectInfo(disk, bucket, path.Join(prefixDir, entry))
if err != nil {
return
}
// Set the Mode to a "regular" file.
fileInfo.Mode = 0
// Trim the suffix that was temporarily added to indicate that this
// is a multipart file.
fileInfo.Name = path.Join(prefixDir, entry)
fileInfo.Size = info.Size
fileInfo.MD5Sum = info.MD5Sum
fileInfo.ModTime = info.ModTime
return
}
if fileInfo, err = disk.StatFile(bucket, path.Join(prefixDir, entry)); err != nil {
return
}
// Object name needs to be full path.
fileInfo.Name = path.Join(prefixDir, entry)
return
}
var markerBase, markerDir string
if marker != "" {
// Ex: if marker="four/five.txt", markerDir="four/" markerBase="five.txt"
markerSplit := strings.SplitN(marker, slashSeparator, 2)
markerDir = markerSplit[0]
if len(markerSplit) == 2 {
markerDir += slashSeparator
markerBase = markerSplit[1]
}
}
entries, err := disk.ListDir(bucket, prefixDir)
if err != nil {
send(treeWalkResult{err: err})
return false
}
if entryPrefixMatch != "" {
for i, entry := range entries {
if !strings.HasPrefix(entry, entryPrefixMatch) {
entries[i] = ""
}
}
}
// For XL multipart files strip the trailing "/" and append ".minio.multipart" to the entry so that
// entryToFileInfo() can call StatFile for regular files or getMultipartObjectInfo() for multipart files.
for i, entry := range entries {
if isXL && strings.HasSuffix(entry, slashSeparator) {
if isMultipartObject(disk, bucket, path.Join(prefixDir, entry)) {
entries[i] = strings.TrimSuffix(entry, slashSeparator) + multipartSuffix
}
}
}
sort.Sort(byMultipartFiles(entries))
// Skip the empty strings
for len(entries) > 0 && entries[0] == "" {
entries = entries[1:]
}
if len(entries) == 0 {
return true
}
// example:
// If markerDir="four/" Search() returns the index of "four/" in the sorted
// entries list so we skip all the entries till "four/"
idx := sort.Search(len(entries), func(i int) bool {
return strings.TrimSuffix(entries[i], multipartSuffix) >= markerDir
})
entries = entries[idx:]
*count += len(entries)
for i, entry := range entries {
if i == 0 && markerDir == entry {
if !recursive {
// Skip as the marker would already be listed in the previous listing.
*count--
continue
}
if recursive && !strings.HasSuffix(entry, slashSeparator) {
// We should not skip for recursive listing and if markerDir is a directory
// for ex. if marker is "four/five.txt" markerDir will be "four/" which
// should not be skipped, instead it will need to be treeWalk()'ed into.
// Skip if it is a file though as it would be listed in previous listing.
*count--
continue
}
}
if recursive && strings.HasSuffix(entry, slashSeparator) {
// If the entry is a directory, we will need recurse into it.
markerArg := ""
if entry == markerDir {
// We need to pass "five.txt" as marker only if we are
// recursing into "four/"
markerArg = markerBase
}
*count--
prefixMatch := "" // Valid only for first level treeWalk and empty for subdirectories.
if !treeWalk(layer, bucket, path.Join(prefixDir, entry), prefixMatch, markerArg, recursive, send, count) {
return false
}
continue
}
*count--
fileInfo, err := entryToFileInfo(entry)
if err != nil {
// The file got deleted in the interim between ListDir() and StatFile()
// Ignore error and continue.
continue
}
if !send(treeWalkResult{fileInfo: fileInfo}) {
return false
}
}
return true
}
// Initiate a new treeWalk in a goroutine.
func startTreeWalk(layer ObjectLayer, bucket, prefix, marker string, recursive bool) *treeWalker {
// Example 1
// If prefix is "one/two/three/" and marker is "one/two/three/four/five.txt"
// treeWalk is called with prefixDir="one/two/three/" and marker="four/five.txt"
// and entryPrefixMatch=""
// Example 2
// if prefix is "one/two/th" and marker is "one/two/three/four/five.txt"
// treeWalk is called with prefixDir="one/two/" and marker="three/four/five.txt"
// and entryPrefixMatch="th"
ch := make(chan treeWalkResult, maxObjectList)
walkNotify := treeWalker{ch: ch}
entryPrefixMatch := prefix
prefixDir := ""
lastIndex := strings.LastIndex(prefix, slashSeparator)
if lastIndex != -1 {
entryPrefixMatch = prefix[lastIndex+1:]
prefixDir = prefix[:lastIndex+1]
}
count := 0
marker = strings.TrimPrefix(marker, prefixDir)
go func() {
defer close(ch)
send := func(walkResult treeWalkResult) bool {
if count == 0 {
walkResult.end = true
}
timer := time.After(time.Second * 60)
select {
case ch <- walkResult:
return true
case <-timer:
walkNotify.timedOut = true
return false
}
}
treeWalk(layer, bucket, prefixDir, entryPrefixMatch, marker, recursive, send, &count)
}()
return &walkNotify
}
// Save the goroutine reference in the map
func saveTreeWalk(layer ObjectLayer, params listParams, walker *treeWalker) {
var listObjectMap map[listParams][]*treeWalker
var listObjectMapMutex *sync.Mutex
switch l := layer.(type) {
case xlObjects:
listObjectMap = l.listObjectMap
listObjectMapMutex = l.listObjectMapMutex
case fsObjects:
listObjectMap = l.listObjectMap
listObjectMapMutex = l.listObjectMapMutex
}
listObjectMapMutex.Lock()
defer listObjectMapMutex.Unlock()
walkers, _ := listObjectMap[params]
walkers = append(walkers, walker)
listObjectMap[params] = walkers
}
// Lookup the goroutine reference from map
func lookupTreeWalk(layer ObjectLayer, params listParams) *treeWalker {
var listObjectMap map[listParams][]*treeWalker
var listObjectMapMutex *sync.Mutex
switch l := layer.(type) {
case xlObjects:
listObjectMap = l.listObjectMap
listObjectMapMutex = l.listObjectMapMutex
case fsObjects:
listObjectMap = l.listObjectMap
listObjectMapMutex = l.listObjectMapMutex
}
listObjectMapMutex.Lock()
defer listObjectMapMutex.Unlock()
if walkChs, ok := listObjectMap[params]; ok {
for i, walkCh := range walkChs {
if !walkCh.timedOut {
newWalkChs := walkChs[i+1:]
if len(newWalkChs) > 0 {
listObjectMap[params] = newWalkChs
} else {
delete(listObjectMap, params)
}
return walkCh
}
}
// As all channels are timed out, delete the map entry
delete(listObjectMap, params)
}
return nil
}