minio/cmd/metacache-walk.go
Harshavardhana 14e1ace552
remove serializing WalkDir() across all buckets/prefixes on SSDs (#17707)
slower drives get knocked off because they are too slow via 
active monitoring, we do not need to block calls arbitrarily.

Serializing adds latencies for already slow calls, remove
it for SSDs/NVMEs

Also, add a selection with context when writing to `out <-`
channel, to avoid any potential blocks.
2023-07-24 09:30:19 -07:00

448 lines
13 KiB
Go

// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package cmd
import (
"bytes"
"context"
"fmt"
"io"
"net/http"
"net/url"
"runtime/debug"
"sort"
"strconv"
"strings"
xhttp "github.com/minio/minio/internal/http"
xioutil "github.com/minio/minio/internal/ioutil"
"github.com/minio/minio/internal/logger"
)
// WalkDirOptions provides options for WalkDir operations.
type WalkDirOptions struct {
// Bucket to scanner
Bucket string
// Directory inside the bucket.
BaseDir string
// Do a full recursive scan.
Recursive bool
// ReportNotFound will return errFileNotFound if all disks reports the BaseDir cannot be found.
ReportNotFound bool
// FilterPrefix will only return results with given prefix within folder.
// Should never contain a slash.
FilterPrefix string
// ForwardTo will forward to the given object path.
ForwardTo string
// Limit the number of returned objects if > 0.
Limit int
}
// WalkDir will traverse a directory and return all entries found.
// On success a sorted meta cache stream will be returned.
// Metadata has data stripped, if any.
func (s *xlStorage) WalkDir(ctx context.Context, opts WalkDirOptions, wr io.Writer) (err error) {
// Verify if volume is valid and it exists.
volumeDir, err := s.getVolDir(opts.Bucket)
if err != nil {
return err
}
// Stat a volume entry.
if err = Access(volumeDir); err != nil {
if osIsNotExist(err) {
return errVolumeNotFound
} else if isSysErrIO(err) {
return errFaultyDisk
}
return err
}
// Use a small block size to start sending quickly
w := newMetacacheWriter(wr, 16<<10)
w.reuseBlocks = true // We are not sharing results, so reuse buffers.
defer w.Close()
out, err := w.stream()
if err != nil {
return err
}
defer close(out)
var objsReturned int
objReturned := func(metadata []byte) {
if opts.Limit <= 0 {
return
}
if m, _, _ := isIndexedMetaV2(metadata); m != nil && !m.AllHidden(true) {
objsReturned++
}
}
send := func(entry metaCacheEntry) error {
objReturned(entry.metadata)
select {
case <-ctx.Done():
return ctx.Err()
case out <- entry:
}
return nil
}
// Fast exit track to check if we are listing an object with
// a trailing slash, this will avoid to list the object content.
if HasSuffix(opts.BaseDir, SlashSeparator) {
metadata, err := s.readMetadata(ctx, pathJoin(volumeDir,
opts.BaseDir[:len(opts.BaseDir)-1]+globalDirSuffix,
xlStorageFormatFile))
if err == nil {
// if baseDir is already a directory object, consider it
// as part of the list call, this is AWS S3 specific
// behavior.
if err := send(metaCacheEntry{
name: opts.BaseDir,
metadata: metadata,
}); err != nil {
return err
}
} else {
st, sterr := Lstat(pathJoin(volumeDir, opts.BaseDir, xlStorageFormatFile))
if sterr == nil && st.Mode().IsRegular() {
return errFileNotFound
}
}
}
prefix := opts.FilterPrefix
var scanDir func(path string) error
scanDir = func(current string) error {
// Skip forward, if requested...
var sb bytes.Buffer
forward := ""
if len(opts.ForwardTo) > 0 && strings.HasPrefix(opts.ForwardTo, current) {
forward = strings.TrimPrefix(opts.ForwardTo, current)
// Trim further directories and trailing slash.
if idx := strings.IndexByte(forward, '/'); idx > 0 {
forward = forward[:idx]
}
}
if contextCanceled(ctx) {
return ctx.Err()
}
if opts.Limit > 0 && objsReturned >= opts.Limit {
return nil
}
if s.walkMu != nil {
s.walkMu.Lock()
}
entries, err := s.ListDir(ctx, opts.Bucket, current, -1)
if s.walkMu != nil {
s.walkMu.Unlock()
}
if err != nil {
// Folder could have gone away in-between
if err != errVolumeNotFound && err != errFileNotFound {
logger.LogOnceIf(ctx, err, "metacache-walk-scan-dir")
}
if opts.ReportNotFound && err == errFileNotFound && current == opts.BaseDir {
err = errFileNotFound
} else {
err = nil
}
diskHealthCheckOK(ctx, err)
return err
}
diskHealthCheckOK(ctx, err)
if len(entries) == 0 {
return nil
}
dirObjects := make(map[string]struct{})
// Avoid a bunch of cleanup when joining.
current = strings.Trim(current, SlashSeparator)
for i, entry := range entries {
if opts.Limit > 0 && objsReturned >= opts.Limit {
return nil
}
if len(prefix) > 0 && !strings.HasPrefix(entry, prefix) {
// Do not retain the file, since it doesn't
// match the prefix.
entries[i] = ""
continue
}
if len(forward) > 0 && entry < forward {
// Do not retain the file, since its
// lexially smaller than 'forward'
entries[i] = ""
continue
}
if hasSuffixByte(entry, SlashSeparatorChar) {
if strings.HasSuffix(entry, globalDirSuffixWithSlash) {
// Add without extension so it is sorted correctly.
entry = strings.TrimSuffix(entry, globalDirSuffixWithSlash) + slashSeparator
dirObjects[entry] = struct{}{}
entries[i] = entry
continue
}
// Trim slash, since we don't know if this is folder or object.
entries[i] = entries[i][:len(entry)-1]
continue
}
// Do not retain the file.
entries[i] = ""
if contextCanceled(ctx) {
return ctx.Err()
}
// If root was an object return it as such.
if HasSuffix(entry, xlStorageFormatFile) {
var meta metaCacheEntry
if s.walkReadMu != nil {
s.walkReadMu.Lock()
}
meta.metadata, err = s.readMetadata(ctx, pathJoinBuf(&sb, volumeDir, current, entry))
if s.walkReadMu != nil {
s.walkReadMu.Unlock()
}
diskHealthCheckOK(ctx, err)
if err != nil {
// It is totally possible that xl.meta was overwritten
// while being concurrently listed at the same time in
// such scenarios the 'xl.meta' might get truncated
if !IsErrIgnored(err, io.EOF, io.ErrUnexpectedEOF) {
logger.LogOnceIf(ctx, err, "metacache-walk-read-metadata")
}
continue
}
meta.name = strings.TrimSuffix(entry, xlStorageFormatFile)
meta.name = strings.TrimSuffix(meta.name, SlashSeparator)
meta.name = pathJoinBuf(&sb, current, meta.name)
meta.name = decodeDirObject(meta.name)
if err := send(meta); err != nil {
return err
}
return nil
}
// Check legacy.
if HasSuffix(entry, xlStorageFormatFileV1) {
var meta metaCacheEntry
meta.metadata, err = xioutil.ReadFile(pathJoinBuf(&sb, volumeDir, current, entry))
diskHealthCheckOK(ctx, err)
if err != nil {
if !IsErrIgnored(err, io.EOF, io.ErrUnexpectedEOF) {
logger.LogIf(ctx, err)
}
continue
}
meta.name = strings.TrimSuffix(entry, xlStorageFormatFileV1)
meta.name = strings.TrimSuffix(meta.name, SlashSeparator)
meta.name = pathJoinBuf(&sb, current, meta.name)
if err := send(meta); err != nil {
return err
}
return nil
}
// Skip all other files.
}
// Process in sort order.
sort.Strings(entries)
dirStack := make([]string, 0, 5)
prefix = "" // Remove prefix after first level as we have already filtered the list.
if len(forward) > 0 {
// Conservative forwarding. Entries may be either objects or prefixes.
for i, entry := range entries {
if entry >= forward || strings.HasPrefix(forward, entry) {
entries = entries[i:]
break
}
}
}
for _, entry := range entries {
if opts.Limit > 0 && objsReturned >= opts.Limit {
return nil
}
if entry == "" {
continue
}
if contextCanceled(ctx) {
return ctx.Err()
}
meta := metaCacheEntry{name: pathJoinBuf(&sb, current, entry)}
// If directory entry on stack before this, pop it now.
for len(dirStack) > 0 && dirStack[len(dirStack)-1] < meta.name {
pop := dirStack[len(dirStack)-1]
out <- metaCacheEntry{name: pop}
if opts.Recursive {
// Scan folder we found. Should be in correct sort order where we are.
err := scanDir(pop)
if err != nil && !IsErrIgnored(err, context.Canceled) {
logger.LogIf(ctx, err)
}
}
dirStack = dirStack[:len(dirStack)-1]
}
// All objects will be returned as directories, there has been no object check yet.
// Check it by attempting to read metadata.
_, isDirObj := dirObjects[entry]
if isDirObj {
meta.name = meta.name[:len(meta.name)-1] + globalDirSuffixWithSlash
}
if s.walkReadMu != nil {
s.walkReadMu.Lock()
}
meta.metadata, err = s.readMetadata(ctx, pathJoinBuf(&sb, volumeDir, meta.name, xlStorageFormatFile))
if s.walkReadMu != nil {
s.walkReadMu.Unlock()
}
diskHealthCheckOK(ctx, err)
switch {
case err == nil:
// It was an object
if isDirObj {
meta.name = strings.TrimSuffix(meta.name, globalDirSuffixWithSlash) + slashSeparator
}
if err := send(meta); err != nil {
return err
}
case osIsNotExist(err), isSysErrIsDir(err):
meta.metadata, err = xioutil.ReadFile(pathJoinBuf(&sb, volumeDir, meta.name, xlStorageFormatFileV1))
diskHealthCheckOK(ctx, err)
if err == nil {
// It was an object
if err := send(meta); err != nil {
return err
}
continue
}
// NOT an object, append to stack (with slash)
// If dirObject, but no metadata (which is unexpected) we skip it.
if !isDirObj {
if !isDirEmpty(pathJoinBuf(&sb, volumeDir, meta.name)) {
dirStack = append(dirStack, meta.name+slashSeparator)
}
}
case isSysErrNotDir(err):
// skip
}
}
// If directory entry left on stack, pop it now.
for len(dirStack) > 0 {
if opts.Limit > 0 && objsReturned >= opts.Limit {
return nil
}
if contextCanceled(ctx) {
return ctx.Err()
}
pop := dirStack[len(dirStack)-1]
out <- metaCacheEntry{name: pop}
if opts.Recursive {
// Scan folder we found. Should be in correct sort order where we are.
logger.LogIf(ctx, scanDir(pop))
}
dirStack = dirStack[:len(dirStack)-1]
}
return nil
}
// Stream output.
return scanDir(opts.BaseDir)
}
func (p *xlStorageDiskIDCheck) WalkDir(ctx context.Context, opts WalkDirOptions, wr io.Writer) (err error) {
ctx, done, err := p.TrackDiskHealth(ctx, storageMetricWalkDir, opts.Bucket, opts.BaseDir)
if err != nil {
return err
}
defer done(&err)
return p.storage.WalkDir(ctx, opts, wr)
}
// WalkDir will traverse a directory and return all entries found.
// On success a meta cache stream will be returned, that should be closed when done.
func (client *storageRESTClient) WalkDir(ctx context.Context, opts WalkDirOptions, wr io.Writer) error {
values := make(url.Values)
values.Set(storageRESTVolume, opts.Bucket)
values.Set(storageRESTDirPath, opts.BaseDir)
values.Set(storageRESTRecursive, strconv.FormatBool(opts.Recursive))
values.Set(storageRESTReportNotFound, strconv.FormatBool(opts.ReportNotFound))
values.Set(storageRESTPrefixFilter, opts.FilterPrefix)
values.Set(storageRESTForwardFilter, opts.ForwardTo)
respBody, err := client.call(ctx, storageRESTMethodWalkDir, values, nil, -1)
if err != nil {
logger.LogIf(ctx, err)
return err
}
defer xhttp.DrainBody(respBody)
return waitForHTTPStream(respBody, wr)
}
// WalkDirHandler - remote caller to list files and folders in a requested directory path.
func (s *storageRESTServer) WalkDirHandler(w http.ResponseWriter, r *http.Request) {
if !s.IsValid(w, r) {
return
}
volume := r.Form.Get(storageRESTVolume)
dirPath := r.Form.Get(storageRESTDirPath)
recursive, err := strconv.ParseBool(r.Form.Get(storageRESTRecursive))
if err != nil {
s.writeErrorResponse(w, err)
return
}
var reportNotFound bool
if v := r.Form.Get(storageRESTReportNotFound); v != "" {
reportNotFound, err = strconv.ParseBool(v)
if err != nil {
s.writeErrorResponse(w, err)
return
}
}
prefix := r.Form.Get(storageRESTPrefixFilter)
forward := r.Form.Get(storageRESTForwardFilter)
writer := streamHTTPResponse(w)
defer func() {
if r := recover(); r != nil {
debug.PrintStack()
writer.CloseWithError(fmt.Errorf("panic: %v", r))
}
}()
writer.CloseWithError(s.storage.WalkDir(r.Context(), WalkDirOptions{
Bucket: volume,
BaseDir: dirPath,
Recursive: recursive,
ReportNotFound: reportNotFound,
FilterPrefix: prefix,
ForwardTo: forward,
}, writer))
}