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| 1 // Copyright 2015 The LUCI 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 hierarchy | |
| 16 | |
| 17 import ( | |
| 18 "bytes" | |
| 19 "encoding/hex" | |
| 20 "errors" | |
| 21 "fmt" | |
| 22 "strconv" | |
| 23 "strings" | |
| 24 "unicode/utf8" | |
| 25 | |
| 26 ds "github.com/luci/gae/service/datastore" | |
| 27 "github.com/luci/luci-go/common/data/cmpbin" | |
| 28 ) | |
| 29 | |
| 30 type componentIDType string | |
| 31 | |
| 32 const ( | |
| 33 numericStreamID componentIDType = "n" | |
| 34 textStreamID componentIDType = "s" | |
| 35 numericPathID componentIDType = "y" | |
| 36 textPathID componentIDType = "z" | |
| 37 ) | |
| 38 | |
| 39 // componentID is the datastore ID for a component. | |
| 40 // | |
| 41 // A component represents a single component, and is keyed on the | |
| 42 // component's value and whether the component is a stream or path component. | |
| 43 // | |
| 44 // A log stream path is broken into several components. For example, | |
| 45 // "foo/bar/+/baz/qux" is broken into ["foo", "bar", "+", "baz", "qux"]. The | |
| 46 // intermediate pieces, "foo", "bar", and "baz" are "path components" (e.g., | |
| 47 // directory name). The terminating component, "qux", is the stream component | |
| 48 // (e.g., file names), since adding it generates a valid stream name. | |
| 49 // | |
| 50 // Note that two streams, "foo/+/bar" and "foo/+/bar/baz", result in components | |
| 51 // "bar". In the first, "bar" is a path component, and in the second "bar" is a | |
| 52 // stream component. | |
| 53 // | |
| 54 // Path component IDs have "~" prepended to them, since "~" is not a valid | |
| 55 // initial stream name character and "~" comes bytewise after all valid | |
| 56 // characters, this will cause paths to sort after streams for a given hierarchy | |
| 57 // level. | |
| 58 type componentID struct { | |
| 59 // parent is the name of this component's parent. | |
| 60 parent string | |
| 61 // name is the name of this component. | |
| 62 name string | |
| 63 // stream is true if this is a stream component. | |
| 64 stream bool | |
| 65 } | |
| 66 | |
| 67 var _ ds.PropertyConverter = (*componentID)(nil) | |
| 68 | |
| 69 // ToProperty implements ds.PropertyConverter | |
| 70 func (id *componentID) ToProperty() (ds.Property, error) { | |
| 71 return ds.MkPropertyNI(id.key()), nil | |
| 72 } | |
| 73 | |
| 74 // FromProperty implements ds.PropertyConverter | |
| 75 func (id *componentID) FromProperty(p ds.Property) error { | |
| 76 if p.Type() != ds.PTString { | |
| 77 return fmt.Errorf("wrong type for property: %s", p.Type()) | |
| 78 } | |
| 79 return id.setID(p.Value().(string)) | |
| 80 } | |
| 81 | |
| 82 func (id *componentID) key() string { | |
| 83 name, numeric := id.maybeNumericID() | |
| 84 return fmt.Sprintf("%s~%s~%s", id.sortedPrefix(numeric), name, id.parent
) | |
| 85 } | |
| 86 | |
| 87 func (id *componentID) setID(s string) error { | |
| 88 parts := strings.SplitN(s, "~", 3) | |
| 89 if len(parts) != 3 { | |
| 90 return errors.New("missing minimal key") | |
| 91 } | |
| 92 | |
| 93 id.name, id.parent = parts[1], parts[2] | |
| 94 numeric := false | |
| 95 switch p := componentIDType(parts[0]); p { | |
| 96 case numericStreamID: | |
| 97 id.stream = true | |
| 98 numeric = true | |
| 99 | |
| 100 case textStreamID: | |
| 101 id.stream = true | |
| 102 | |
| 103 case numericPathID: | |
| 104 id.stream = false | |
| 105 numeric = true | |
| 106 | |
| 107 case textPathID: | |
| 108 id.stream = false | |
| 109 | |
| 110 default: | |
| 111 return fmt.Errorf("unknown type prefix %q", p) | |
| 112 } | |
| 113 | |
| 114 if numeric { | |
| 115 // Split numeric encoding from leading zero count. | |
| 116 numParts := strings.SplitN(id.name, ":", 2) | |
| 117 | |
| 118 // Render numeric value. | |
| 119 value, err := decodeCmpbinHexUint(numParts[0]) | |
| 120 if err != nil { | |
| 121 return fmt.Errorf("failed to decode value: %v", err) | |
| 122 } | |
| 123 | |
| 124 id.name = strconv.FormatUint(value, 10) | |
| 125 | |
| 126 // Re-add leading zeroes, if any were present. | |
| 127 if len(numParts) == 2 { | |
| 128 leadingZeroes, err := decodeCmpbinHexUint(numParts[1]) | |
| 129 if err != nil { | |
| 130 return fmt.Errorf("failed to decode leading zero
es: %v", err) | |
| 131 } | |
| 132 | |
| 133 id.name = strings.Repeat("0", int(leadingZeroes)) + id.n
ame | |
| 134 } | |
| 135 } | |
| 136 | |
| 137 return nil | |
| 138 } | |
| 139 | |
| 140 func (id *componentID) maybeNumericID() (name string, numeric bool) { | |
| 141 name = id.name | |
| 142 | |
| 143 // Is our name entirely numeric? | |
| 144 v, err := strconv.ParseUint(name, 10, 64) | |
| 145 if err != nil { | |
| 146 return | |
| 147 } | |
| 148 | |
| 149 // This is a numeric value. Generate a numeric-sortable string. | |
| 150 // | |
| 151 // Count the leading zeroes. We do this because the same numeric value c
an be | |
| 152 // expressed with different strings, and we need to differentiate them. | |
| 153 // | |
| 154 // For example, "000123" vs. "123". | |
| 155 // | |
| 156 // We do this by appending ":#", where # is the hex-encoded cmpbin-encod
ed | |
| 157 // count of leading zeroes. | |
| 158 var leadingZeroes uint64 | |
| 159 for _, r := range name { | |
| 160 if r != '0' { | |
| 161 break | |
| 162 } | |
| 163 leadingZeroes++ | |
| 164 } | |
| 165 if len(name) > 0 && leadingZeroes == uint64(utf8.RuneCountInString(name)
) { | |
| 166 leadingZeroes-- | |
| 167 } | |
| 168 | |
| 169 var buf bytes.Buffer | |
| 170 name = encodeCmpbinHexUint(&buf, v) | |
| 171 if leadingZeroes > 0 { | |
| 172 name += ":" + encodeCmpbinHexUint(&buf, leadingZeroes) | |
| 173 } | |
| 174 numeric = true | |
| 175 return | |
| 176 } | |
| 177 | |
| 178 func (id *componentID) sortedPrefix(numeric bool) componentIDType { | |
| 179 switch { | |
| 180 case id.stream && numeric: | |
| 181 // Numeric stream element. | |
| 182 return numericStreamID | |
| 183 case id.stream: | |
| 184 // Non-numeric stream element. | |
| 185 return textStreamID | |
| 186 case numeric: | |
| 187 // Numeric path component. | |
| 188 return numericPathID | |
| 189 default: | |
| 190 // Non-numeric path component. | |
| 191 return textPathID | |
| 192 } | |
| 193 } | |
| 194 | |
| 195 func encodeCmpbinHexUint(b *bytes.Buffer, v uint64) string { | |
| 196 b.Reset() | |
| 197 if _, err := cmpbin.WriteUint(b, v); err != nil { | |
| 198 // Cannot happen when writing to a Buffer. | |
| 199 panic(err) | |
| 200 } | |
| 201 return hex.EncodeToString(b.Bytes()) | |
| 202 } | |
| 203 | |
| 204 func decodeCmpbinHexUint(s string) (uint64, error) { | |
| 205 buf := make([]byte, hex.DecodedLen(len(s))) | |
| 206 if _, err := hex.Decode(buf, []byte(s)); err != nil { | |
| 207 return 0, err | |
| 208 } | |
| 209 | |
| 210 v, _, err := cmpbin.ReadUint(bytes.NewReader(buf)) | |
| 211 return v, err | |
| 212 } | |
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Chromium Code Reviews
Issue 2991253004:
[logdog] Remove list functionality. (Closed)
