db.go

Documentation: go.etcd.io/etcd/server/v3/etcdserver/api/snap

     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 snap
    16  
    17  import (
    18  	"errors"
    19  	"fmt"
    20  	"io"
    21  	"io/ioutil"
    22  	"os"
    23  	"path/filepath"
    24  	"time"
    25  
    26  	"go.etcd.io/etcd/client/pkg/v3/fileutil"
    27  
    28  	humanize "github.com/dustin/go-humanize"
    29  	"go.uber.org/zap"
    30  )
    31  
    32  var ErrNoDBSnapshot = errors.New("snap: snapshot file doesn't exist")
    33  
    34  // SaveDBFrom saves snapshot of the database from the given reader. It
    35  // guarantees the save operation is atomic.
    36  func (s *Snapshotter) SaveDBFrom(r io.Reader, id uint64) (int64, error) {
    37  	start := time.Now()
    38  
    39  	f, err := ioutil.TempFile(s.dir, "tmp")
    40  	if err != nil {
    41  		return 0, err
    42  	}
    43  	var n int64
    44  	n, err = io.Copy(f, r)
    45  	if err == nil {
    46  		fsyncStart := time.Now()
    47  		err = fileutil.Fsync(f)
    48  		snapDBFsyncSec.Observe(time.Since(fsyncStart).Seconds())
    49  	}
    50  	f.Close()
    51  	if err != nil {
    52  		os.Remove(f.Name())
    53  		return n, err
    54  	}
    55  	fn := s.dbFilePath(id)
    56  	if fileutil.Exist(fn) {
    57  		os.Remove(f.Name())
    58  		return n, nil
    59  	}
    60  	err = os.Rename(f.Name(), fn)
    61  	if err != nil {
    62  		os.Remove(f.Name())
    63  		return n, err
    64  	}
    65  
    66  	s.lg.Info(
    67  		"saved database snapshot to disk",
    68  		zap.String("path", fn),
    69  		zap.Int64("bytes", n),
    70  		zap.String("size", humanize.Bytes(uint64(n))),
    71  	)
    72  
    73  	snapDBSaveSec.Observe(time.Since(start).Seconds())
    74  	return n, nil
    75  }
    76  
    77  // DBFilePath returns the file path for the snapshot of the database with
    78  // given id. If the snapshot does not exist, it returns error.
    79  func (s *Snapshotter) DBFilePath(id uint64) (string, error) {
    80  	if _, err := fileutil.ReadDir(s.dir); err != nil {
    81  		return "", err
    82  	}
    83  	fn := s.dbFilePath(id)
    84  	if fileutil.Exist(fn) {
    85  		return fn, nil
    86  	}
    87  	if s.lg != nil {
    88  		s.lg.Warn(
    89  			"failed to find [SNAPSHOT-INDEX].snap.db",
    90  			zap.Uint64("snapshot-index", id),
    91  			zap.String("snapshot-file-path", fn),
    92  			zap.Error(ErrNoDBSnapshot),
    93  		)
    94  	}
    95  	return "", ErrNoDBSnapshot
    96  }
    97  
    98  func (s *Snapshotter) dbFilePath(id uint64) string {
    99  	return filepath.Join(s.dir, fmt.Sprintf("%016x.snap.db", id))
   100  }
   101
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