repair.go

Documentation: go.etcd.io/etcd/server/v3/wal

     1  // Copyright 2015 The etcd Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package wal
    16  
    17  import (
    18  	"errors"
    19  	"io"
    20  	"os"
    21  	"path/filepath"
    22  	"time"
    23  
    24  	"go.etcd.io/etcd/client/pkg/v3/fileutil"
    25  	"go.etcd.io/etcd/server/v3/wal/walpb"
    26  	"go.uber.org/zap"
    27  )
    28  
    29  // Repair tries to repair ErrUnexpectedEOF in the
    30  // last wal file by truncating.
    31  func Repair(lg *zap.Logger, dirpath string) bool {
    32  	if lg == nil {
    33  		lg = zap.NewNop()
    34  	}
    35  	f, err := openLast(lg, dirpath)
    36  	if err != nil {
    37  		return false
    38  	}
    39  	defer f.Close()
    40  
    41  	lg.Info("repairing", zap.String("path", f.Name()))
    42  
    43  	rec := &walpb.Record{}
    44  	decoder := newDecoder(fileutil.NewFileReader(f.File))
    45  	for {
    46  		lastOffset := decoder.lastOffset()
    47  		err := decoder.decode(rec)
    48  		switch {
    49  		case err == nil:
    50  			// update crc of the decoder when necessary
    51  			switch rec.Type {
    52  			case crcType:
    53  				crc := decoder.crc.Sum32()
    54  				// current crc of decoder must match the crc of the record.
    55  				// do no need to match 0 crc, since the decoder is a new one at this case.
    56  				if crc != 0 && rec.Validate(crc) != nil {
    57  					return false
    58  				}
    59  				decoder.updateCRC(rec.Crc)
    60  			}
    61  			continue
    62  
    63  		case errors.Is(err, io.EOF):
    64  			lg.Info("repaired", zap.String("path", f.Name()), zap.Error(io.EOF))
    65  			return true
    66  
    67  		case errors.Is(err, io.ErrUnexpectedEOF):
    68  			bf, bferr := os.Create(f.Name() + ".broken")
    69  			if bferr != nil {
    70  				lg.Warn("failed to create backup file", zap.String("path", f.Name()+".broken"), zap.Error(bferr))
    71  				return false
    72  			}
    73  			defer bf.Close()
    74  
    75  			if _, err = f.Seek(0, io.SeekStart); err != nil {
    76  				lg.Warn("failed to read file", zap.String("path", f.Name()), zap.Error(err))
    77  				return false
    78  			}
    79  
    80  			if _, err = io.Copy(bf, f); err != nil {
    81  				lg.Warn("failed to copy", zap.String("from", f.Name()+".broken"), zap.String("to", f.Name()), zap.Error(err))
    82  				return false
    83  			}
    84  
    85  			if err = f.Truncate(lastOffset); err != nil {
    86  				lg.Warn("failed to truncate", zap.String("path", f.Name()), zap.Error(err))
    87  				return false
    88  			}
    89  
    90  			start := time.Now()
    91  			if err = fileutil.Fsync(f.File); err != nil {
    92  				lg.Warn("failed to fsync", zap.String("path", f.Name()), zap.Error(err))
    93  				return false
    94  			}
    95  			walFsyncSec.Observe(time.Since(start).Seconds())
    96  
    97  			lg.Info("repaired", zap.String("path", f.Name()), zap.Error(io.ErrUnexpectedEOF))
    98  			return true
    99  
   100  		default:
   101  			lg.Warn("failed to repair", zap.String("path", f.Name()), zap.Error(err))
   102  			return false
   103  		}
   104  	}
   105  }
   106  
   107  // openLast opens the last wal file for read and write.
   108  func openLast(lg *zap.Logger, dirpath string) (*fileutil.LockedFile, error) {
   109  	names, err := readWALNames(lg, dirpath)
   110  	if err != nil {
   111  		return nil, err
   112  	}
   113  	last := filepath.Join(dirpath, names[len(names)-1])
   114  	return fileutil.LockFile(last, os.O_RDWR, fileutil.PrivateFileMode)
   115  }
   116
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