1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307
|
// Copyright [2019] LinkedIn Corp. Licensed under the Apache License, Version
// 2.0 (the "License"); you may not use this file except in compliance with the
// License. You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
package goavro
import (
"errors"
"fmt"
"io"
"math"
"reflect"
)
func makeMapCodec(st map[string]*Codec, namespace string, schemaMap map[string]interface{}, cb *codecBuilder) (*Codec, error) {
// map type must have values
valueSchema, ok := schemaMap["values"]
if !ok {
return nil, errors.New("Map ought to have values key")
}
valueCodec, err := buildCodec(st, namespace, valueSchema, cb)
if err != nil {
return nil, fmt.Errorf("Map values ought to be valid Avro type: %s", err)
}
return &Codec{
typeName: &name{"map", nullNamespace},
nativeFromBinary: func(buf []byte) (interface{}, []byte, error) {
var err error
var value interface{}
// block count and block size
if value, buf, err = longNativeFromBinary(buf); err != nil {
return nil, nil, fmt.Errorf("cannot decode binary map block count: %s", err)
}
blockCount := value.(int64)
if blockCount < 0 {
// NOTE: A negative block count implies there is a long encoded
// block size following the negative block count. We have no use
// for the block size in this decoder, so we read and discard
// the value.
if blockCount == math.MinInt64 {
// The minimum number for any signed numerical type can
// never be made positive
return nil, nil, fmt.Errorf("cannot decode binary map with block count: %d", blockCount)
}
blockCount = -blockCount // convert to its positive equivalent
if _, buf, err = longNativeFromBinary(buf); err != nil {
return nil, nil, fmt.Errorf("cannot decode binary map block size: %s", err)
}
}
// Ensure block count does not exceed some sane value.
if blockCount > MaxBlockCount {
return nil, nil, fmt.Errorf("cannot decode binary map when block count exceeds MaxBlockCount: %d > %d", blockCount, MaxBlockCount)
}
// NOTE: While the attempt of a RAM optimization shown below is not
// necessary, many encoders will encode all items in a single block.
// We can optimize amount of RAM allocated by runtime for the array
// by initializing the array for that number of items.
mapValues := make(map[string]interface{}, blockCount)
for blockCount != 0 {
// Decode `blockCount` datum values from buffer
for i := int64(0); i < blockCount; i++ {
// first decode the key string
if value, buf, err = stringNativeFromBinary(buf); err != nil {
return nil, nil, fmt.Errorf("cannot decode binary map key: %s", err)
}
key := value.(string) // string decoder always returns a string
if _, ok := mapValues[key]; ok {
return nil, nil, fmt.Errorf("cannot decode binary map: duplicate key: %q", key)
}
// then decode the value
if value, buf, err = valueCodec.nativeFromBinary(buf); err != nil {
return nil, nil, fmt.Errorf("cannot decode binary map value for key %q: %s", key, err)
}
mapValues[key] = value
}
// Decode next blockCount from buffer, because there may be more blocks
if value, buf, err = longNativeFromBinary(buf); err != nil {
return nil, nil, fmt.Errorf("cannot decode binary map block count: %s", err)
}
blockCount = value.(int64)
if blockCount < 0 {
// NOTE: A negative block count implies there is a long
// encoded block size following the negative block count. We
// have no use for the block size in this decoder, so we
// read and discard the value.
if blockCount == math.MinInt64 {
// The minimum number for any signed numerical type can
// never be made positive
return nil, nil, fmt.Errorf("cannot decode binary map with block count: %d", blockCount)
}
blockCount = -blockCount // convert to its positive equivalent
if _, buf, err = longNativeFromBinary(buf); err != nil {
return nil, nil, fmt.Errorf("cannot decode binary map block size: %s", err)
}
}
// Ensure block count does not exceed some sane value.
if blockCount > MaxBlockCount {
return nil, nil, fmt.Errorf("cannot decode binary map when block count exceeds MaxBlockCount: %d > %d", blockCount, MaxBlockCount)
}
}
return mapValues, buf, nil
},
binaryFromNative: func(buf []byte, datum interface{}) ([]byte, error) {
mapValues, err := convertMap(datum)
if err != nil {
return nil, fmt.Errorf("cannot encode binary map: %s", err)
}
keyCount := int64(len(mapValues))
var alreadyEncoded, remainingInBlock int64
for k, v := range mapValues {
if remainingInBlock == 0 { // start a new block
remainingInBlock = keyCount - alreadyEncoded
if remainingInBlock > MaxBlockCount {
// limit block count to MacBlockCount
remainingInBlock = MaxBlockCount
}
buf, _ = longBinaryFromNative(buf, remainingInBlock)
}
// only fails when given non string, so elide error checking
buf, _ = stringBinaryFromNative(buf, k)
// encode the value
if buf, err = valueCodec.binaryFromNative(buf, v); err != nil {
return nil, fmt.Errorf("cannot encode binary map value for key %q: %v: %s", k, v, err)
}
remainingInBlock--
alreadyEncoded++
}
return longBinaryFromNative(buf, 0) // append tailing 0 block count to signal end of Map
},
nativeFromTextual: func(buf []byte) (interface{}, []byte, error) {
return genericMapTextDecoder(buf, valueCodec, nil) // codecFromKey == nil
},
textualFromNative: func(buf []byte, datum interface{}) ([]byte, error) {
return genericMapTextEncoder(buf, datum, valueCodec, nil)
},
}, nil
}
// genericMapTextDecoder decodes a JSON text blob to a native Go map, using the
// codecs from codecFromKey, and if a key is not found in that map, from
// defaultCodec if provided. If defaultCodec is nil, this function returns an
// error if it encounters a map key that is not present in codecFromKey. If
// codecFromKey is nil, every map value will be decoded using defaultCodec, if
// possible.
func genericMapTextDecoder(buf []byte, defaultCodec *Codec, codecFromKey map[string]*Codec) (map[string]interface{}, []byte, error) {
var value interface{}
var err error
var b byte
lencodec := len(codecFromKey)
mapValues := make(map[string]interface{}, lencodec)
if buf, err = advanceAndConsume(buf, '{'); err != nil {
return nil, nil, err
}
if buf, _ = advanceToNonWhitespace(buf); len(buf) == 0 {
return nil, nil, io.ErrShortBuffer
}
// NOTE: Special case empty map
if buf[0] == '}' {
return mapValues, buf[1:], nil
}
// NOTE: Also terminates when read '}' byte.
for len(buf) > 0 {
// decode key string
value, buf, err = stringNativeFromTextual(buf)
if err != nil {
return nil, nil, fmt.Errorf("cannot decode textual map: expected key: %s", err)
}
key := value.(string)
// Is key already used?
if _, ok := mapValues[key]; ok {
return nil, nil, fmt.Errorf("cannot decode textual map: duplicate key: %q", key)
}
// Find a codec for the key
fieldCodec := codecFromKey[key]
if fieldCodec == nil {
fieldCodec = defaultCodec
}
if fieldCodec == nil {
return nil, nil, fmt.Errorf("cannot decode textual map: cannot determine codec: %q", key)
}
// decode colon
if buf, err = advanceAndConsume(buf, ':'); err != nil {
return nil, nil, err
}
// decode value
if buf, _ = advanceToNonWhitespace(buf); len(buf) == 0 {
return nil, nil, io.ErrShortBuffer
}
value, buf, err = fieldCodec.nativeFromTextual(buf)
if err != nil {
return nil, nil, fmt.Errorf("%s for key: %q", err, key)
}
// set map value for key
mapValues[key] = value
// either comma or closing curly brace
if buf, _ = advanceToNonWhitespace(buf); len(buf) == 0 {
return nil, nil, io.ErrShortBuffer
}
switch b = buf[0]; b {
case '}':
return mapValues, buf[1:], nil
case ',':
// no-op
default:
return nil, nil, fmt.Errorf("cannot decode textual map: expected ',' or '}'; received: %q", b)
}
// NOTE: consume comma from above
if buf, _ = advanceToNonWhitespace(buf[1:]); len(buf) == 0 {
return nil, nil, io.ErrShortBuffer
}
}
return nil, nil, io.ErrShortBuffer
}
// genericMapTextEncoder encodes a native Go map to a JSON text blob, using the
// codecs from codecFromKey, and if a key is not found in that map, from
// defaultCodec if provided. If defaultCodec is nil, this function returns an
// error if it encounters a map key that is not present in codecFromKey. If
// codecFromKey is nil, every map value will be encoded using defaultCodec, if
// possible.
func genericMapTextEncoder(buf []byte, datum interface{}, defaultCodec *Codec, codecFromKey map[string]*Codec) ([]byte, error) {
mapValues, err := convertMap(datum)
if err != nil {
return nil, fmt.Errorf("cannot encode textual map: %s", err)
}
var atLeastOne bool
buf = append(buf, '{')
for key, value := range mapValues {
atLeastOne = true
// Find a codec for the key
fieldCodec := codecFromKey[key]
if fieldCodec == nil {
fieldCodec = defaultCodec
}
if fieldCodec == nil {
return nil, fmt.Errorf("cannot encode textual map: cannot determine codec: %q", key)
}
// Encode key string
buf, err = stringTextualFromNative(buf, key)
if err != nil {
return nil, err
}
buf = append(buf, ':')
// Encode value
buf, err = fieldCodec.textualFromNative(buf, value)
if err != nil {
// field was specified in datum; therefore its value was invalid
return nil, fmt.Errorf("cannot encode textual map: value for %q does not match its schema: %s", key, err)
}
buf = append(buf, ',')
}
if atLeastOne {
return append(buf[:len(buf)-1], '}'), nil
}
return append(buf, '}'), nil
}
// convertMap converts datum to map[string]interface{} if possible.
func convertMap(datum interface{}) (map[string]interface{}, error) {
mapValues, ok := datum.(map[string]interface{})
if ok {
return mapValues, nil
}
// NOTE: When given a map of any other type, zip values to items as a
// convenience to client.
v := reflect.ValueOf(datum)
if v.Kind() != reflect.Map {
return nil, fmt.Errorf("cannot create map[string]interface{}: expected map[string]...; received: %T", datum)
}
// NOTE: Two better alternatives to the current algorithm are:
// (1) mutate the reflection tuple underneath to convert the
// map[string]int, for example, to map[string]interface{}, with
// O(1) complexity.
// (2) use copy builtin to zip the data items over with O(n) complexity,
// but more efficient than what's below.
mapValues = make(map[string]interface{}, v.Len())
for _, key := range v.MapKeys() {
k, ok := key.Interface().(string)
if !ok {
// bail when map key type is not string
return nil, fmt.Errorf("cannot create map[string]interface{}: expected map[string]...; received: %T", datum)
}
mapValues[string(k)] = v.MapIndex(key).Interface()
}
return mapValues, nil
}
|