vitess.io/vitess@v0.16.2/go/vt/topo/zk2topo/file.go (about) 1 /* 2 Copyright 2019 The Vitess Authors. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 package zk2topo 18 19 import ( 20 "bytes" 21 "fmt" 22 "path" 23 24 "context" 25 26 "github.com/z-division/go-zookeeper/zk" 27 28 "vitess.io/vitess/go/vt/topo" 29 ) 30 31 // Create is part of the topo.Conn interface. 32 func (zs *Server) Create(ctx context.Context, filePath string, contents []byte) (topo.Version, error) { 33 zkPath := path.Join(zs.root, filePath) 34 35 pathCreated, err := CreateRecursive(ctx, zs.conn, zkPath, contents, 0, zk.WorldACL(PermFile), -1) 36 if err != nil { 37 return nil, convertError(err, zkPath) 38 } 39 40 // Now do a Get to get the version. If the content doesn't 41 // match, it means someone else already changed the file, 42 // between our Create and Get. It is safer to return an error here, 43 // and let the calling process recover if it can. 44 data, stat, err := zs.conn.Get(ctx, pathCreated) 45 if err != nil { 46 return nil, convertError(err, zkPath) 47 } 48 if !bytes.Equal(data, contents) { 49 return nil, fmt.Errorf("file contents changed between zk.Create and zk.Get") 50 } 51 52 return ZKVersion(stat.Version), nil 53 } 54 55 // Update is part of the topo.Conn interface. 56 func (zs *Server) Update(ctx context.Context, filePath string, contents []byte, version topo.Version) (topo.Version, error) { 57 zkPath := path.Join(zs.root, filePath) 58 59 // Interpret the version 60 var zkVersion int32 61 if version != nil { 62 zkVersion = int32(version.(ZKVersion)) 63 } else { 64 zkVersion = -1 65 } 66 67 stat, err := zs.conn.Set(ctx, zkPath, contents, zkVersion) 68 if zkVersion == -1 && err == zk.ErrNoNode { 69 // In zookeeper, an unconditional set of a nonexisting 70 // node will return ErrNoNode. In that case, we want 71 // to Create. 72 return zs.Create(ctx, filePath, contents) 73 } 74 if err != nil { 75 return nil, convertError(err, zkPath) 76 } 77 return ZKVersion(stat.Version), nil 78 } 79 80 // Get is part of the topo.Conn interface. 81 func (zs *Server) Get(ctx context.Context, filePath string) ([]byte, topo.Version, error) { 82 zkPath := path.Join(zs.root, filePath) 83 84 contents, stat, err := zs.conn.Get(ctx, zkPath) 85 if err != nil { 86 return nil, nil, convertError(err, zkPath) 87 } 88 return contents, ZKVersion(stat.Version), nil 89 } 90 91 // List is part of the topo.Conn interface. 92 func (zs *Server) List(ctx context.Context, filePathPrefix string) ([]topo.KVInfo, error) { 93 return nil, topo.NewError(topo.NoImplementation, "List not supported in ZK2 topo") 94 } 95 96 // Delete is part of the topo.Conn interface. 97 func (zs *Server) Delete(ctx context.Context, filePath string, version topo.Version) error { 98 zkPath := path.Join(zs.root, filePath) 99 100 // Interpret the version 101 var zkVersion int32 102 if version != nil { 103 zkVersion = int32(version.(ZKVersion)) 104 } else { 105 zkVersion = -1 106 } 107 108 if err := zs.conn.Delete(ctx, zkPath, zkVersion); err != nil { 109 return convertError(err, zkPath) 110 } 111 return zs.recursiveDeleteParentIfEmpty(ctx, filePath) 112 } 113 114 func (zs *Server) recursiveDeleteParentIfEmpty(ctx context.Context, filePath string) error { 115 dir := path.Dir(filePath) 116 if dir == "" || dir == "/" || dir == "." { 117 // we reached the top 118 return nil 119 } 120 zkPath := path.Join(zs.root, dir) 121 err := zs.conn.Delete(ctx, zkPath, -1) 122 switch err { 123 case nil: 124 // we keep going up 125 return zs.recursiveDeleteParentIfEmpty(ctx, dir) 126 case zk.ErrNotEmpty, zk.ErrNoNode: 127 // we're done (not empty, or someone beat us to deletion) 128 return nil 129 default: 130 return err 131 } 132 }