go.etcd.io/etcd@v3.3.27+incompatible/wal/file_pipeline.go (about) 1 // Copyright 2016 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 "fmt" 19 "os" 20 "path/filepath" 21 22 "github.com/coreos/etcd/pkg/fileutil" 23 ) 24 25 // filePipeline pipelines allocating disk space 26 type filePipeline struct { 27 // dir to put files 28 dir string 29 // size of files to make, in bytes 30 size int64 31 // count number of files generated 32 count int 33 34 filec chan *fileutil.LockedFile 35 errc chan error 36 donec chan struct{} 37 } 38 39 func newFilePipeline(dir string, fileSize int64) *filePipeline { 40 fp := &filePipeline{ 41 dir: dir, 42 size: fileSize, 43 filec: make(chan *fileutil.LockedFile), 44 errc: make(chan error, 1), 45 donec: make(chan struct{}), 46 } 47 go fp.run() 48 return fp 49 } 50 51 // Open returns a fresh file for writing. Rename the file before calling 52 // Open again or there will be file collisions. 53 func (fp *filePipeline) Open() (f *fileutil.LockedFile, err error) { 54 select { 55 case f = <-fp.filec: 56 case err = <-fp.errc: 57 } 58 return f, err 59 } 60 61 func (fp *filePipeline) Close() error { 62 close(fp.donec) 63 return <-fp.errc 64 } 65 66 func (fp *filePipeline) alloc() (f *fileutil.LockedFile, err error) { 67 // count % 2 so this file isn't the same as the one last published 68 fpath := filepath.Join(fp.dir, fmt.Sprintf("%d.tmp", fp.count%2)) 69 if f, err = fileutil.LockFile(fpath, os.O_CREATE|os.O_WRONLY, fileutil.PrivateFileMode); err != nil { 70 return nil, err 71 } 72 if err = fileutil.Preallocate(f.File, fp.size, true); err != nil { 73 plog.Errorf("failed to allocate space when creating new wal file (%v)", err) 74 f.Close() 75 return nil, err 76 } 77 fp.count++ 78 return f, nil 79 } 80 81 func (fp *filePipeline) run() { 82 defer close(fp.errc) 83 for { 84 f, err := fp.alloc() 85 if err != nil { 86 fp.errc <- err 87 return 88 } 89 select { 90 case fp.filec <- f: 91 case <-fp.donec: 92 os.Remove(f.Name()) 93 f.Close() 94 return 95 } 96 } 97 }