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Reuse CaseClassJsonDecoder for faster decoding of small generic rec…
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@plokhotnyuk
plokhotnyuk committed Jan 10, 2025
1 parent b95d200 commit 4b6228a
Showing 1 changed file with 100 additions and 65 deletions.
165 changes: 100 additions & 65 deletions zio-schema-json/shared/src/main/scala/zio/schema/codec/JsonCodec.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -971,76 +971,82 @@ object JsonCodec {
private def recordDecoder(
schema: GenericRecord,
discriminator: Option[String]
): ZJsonDecoder[ListMap[String, Any]] = new ZJsonDecoder[ListMap[String, Any]] {
private[this] val fields = schema.fields.toArray
private[this] val spansWithDecoders =
new util.HashMap[String, (JsonError.ObjectAccess, ZJsonDecoder[Any])](fields.length << 1) {
fields.foreach { field =>
val spanWithDecoder =
(JsonError.ObjectAccess(field.fieldName), schemaDecoder(field.schema).asInstanceOf[ZJsonDecoder[Any]])
field.nameAndAliases.foreach(put(_, spanWithDecoder))
}
}
private[this] val skipExtraFields = !schema.annotations.exists(_.isInstanceOf[rejectExtraFields])

override def unsafeDecode(trace: List[JsonError], in: RetractReader): ListMap[String, Any] = {
val lexer = Lexer
var continue = true
if (discriminator eq None) {
lexer.char(trace, in, '{')
continue = lexer.firstField(trace, in)
}
val map = new util.HashMap[String, Any](fields.length << 1)
while (continue) {
val fieldNameOrAlias = lexer.string(trace, in).toString
val spanWithDecoder = spansWithDecoders.get(fieldNameOrAlias)
if (spanWithDecoder ne null) {
val span = spanWithDecoder._1
val dec = spanWithDecoder._2
val trace_ = span :: trace
lexer.char(trace_, in, ':')
val fieldName = span.field // reuse strings with calculated hashCode
val prev = map.put(fieldName, dec.unsafeDecode(trace_, in))
if (prev != null) error("duplicate", trace_)
} else if (skipExtraFields || discriminator.contains(fieldNameOrAlias)) {
lexer.char(trace, in, ':')
lexer.skipValue(trace, in)
} else error("extra field", trace)
continue = lexer.nextField(trace, in)
}
var idx = 0
while (idx < fields.length) {
val field = fields(idx)
idx += 1
val fieldName = field.fieldName // reuse strings with calculated hashCode
if (map.get(fieldName) == null) {
map.put( // mitigation of a linking error for `map.computeIfAbsent` in Scala.js
fieldName, {
if ((field.optional || field.transient) && field.defaultValue.isDefined) {
field.defaultValue.get
} else {
var schema = field.schema
schema match {
case l: Schema.Lazy[_] => schema = l.schema
case _ =>
}
schema match {
case _: Schema.Optional[_] => None
case collection: Schema.Collection[_, _] => collection.empty
case _ => error("missing", spansWithDecoders.get(fieldName)._1 :: trace)
): ZJsonDecoder[ListMap[String, Any]] =
if (schema.fields.foldLeft(0)(_ + _.nameAndAliases.size) <= 64) {
val ccjd = CaseClassJsonDecoder(schema, discriminator)
(trace: List[JsonError], in: RetractReader) => ccjd.unsafeDecodeListMap(trace, in)
} else {
new ZJsonDecoder[ListMap[String, Any]] {
private[this] val fields = schema.fields.toArray
private[this] val spansWithDecoders =
new util.HashMap[String, (JsonError.ObjectAccess, ZJsonDecoder[Any])](fields.length << 1) {
fields.foreach { field =>
val spanWithDecoder =
(JsonError.ObjectAccess(field.fieldName), schemaDecoder(field.schema).asInstanceOf[ZJsonDecoder[Any]])
field.nameAndAliases.foreach(put(_, spanWithDecoder))
}
}
private[this] val skipExtraFields = !schema.annotations.exists(_.isInstanceOf[rejectExtraFields])

override def unsafeDecode(trace: List[JsonError], in: RetractReader): ListMap[String, Any] = {
val lexer = Lexer
var continue = true
if (discriminator eq None) {
lexer.char(trace, in, '{')
continue = lexer.firstField(trace, in)
}
val map = new util.HashMap[String, Any](fields.length << 1)
while (continue) {
val fieldNameOrAlias = lexer.string(trace, in).toString
val spanWithDecoder = spansWithDecoders.get(fieldNameOrAlias)
if (spanWithDecoder ne null) {
val span = spanWithDecoder._1
val dec = spanWithDecoder._2
val trace_ = span :: trace
lexer.char(trace_, in, ':')
val fieldName = span.field // reuse strings with calculated hashCode
val prev = map.put(fieldName, dec.unsafeDecode(trace_, in))
if (prev != null) error("duplicate", trace_)
} else if (skipExtraFields || discriminator.contains(fieldNameOrAlias)) {
lexer.char(trace, in, ':')
lexer.skipValue(trace, in)
} else error("extra field", trace)
continue = lexer.nextField(trace, in)
}
var idx = 0
while (idx < fields.length) {
val field = fields(idx)
idx += 1
val fieldName = field.fieldName // reuse strings with calculated hashCode
if (map.get(fieldName) == null) {
map.put( // mitigation of a linking error for `map.computeIfAbsent` in Scala.js
fieldName, {
if ((field.optional || field.transient) && field.defaultValue.isDefined) {
field.defaultValue.get
} else {
var schema = field.schema
schema match {
case l: Schema.Lazy[_] => schema = l.schema
case _ =>
}
schema match {
case _: Schema.Optional[_] => None
case collection: Schema.Collection[_, _] => collection.empty
case _ => error("missing", spansWithDecoders.get(fieldName)._1 :: trace)
}
}
}
}
)
}
)
}
(ListMap.newBuilder[String, Any] ++= ({ // to avoid O(n) insert operations
import scala.collection.JavaConverters.mapAsScalaMapConverter // use deprecated class for Scala 2.12 compatibility

map.asScala
}: @scala.annotation.nowarn)).result()
}
}
(ListMap.newBuilder[String, Any] ++= ({ // to avoid O(n) insert operations
import scala.collection.JavaConverters.mapAsScalaMapConverter // use deprecated class for Scala 2.12 compatibility

map.asScala
}: @scala.annotation.nowarn)).result()
}
}

private def fallbackDecoder[A, B](schema: Schema.Fallback[A, B]): ZJsonDecoder[Fallback[A, B]] =
new ZJsonDecoder[Fallback[A, B]] {
Expand Down Expand Up @@ -1553,6 +1559,35 @@ object JsonCodec {
skipExtraFields: Boolean
) {

def unsafeDecodeListMap(trace: List[JsonError], in: RetractReader): ListMap[String, Any] = {
val buffer = unsafeDecodeFields(trace, in)
(ListMap.newBuilder[String, Any] ++= new collection.Map[String, Any] { // only `.iterator` method will be called
override def +[Any](kv: (String, Any)): collection.Map[String, Any] = ???

override def -(key: String): collection.Map[String, Any] = ???

@scala.annotation.nowarn
override def -(key1: String, key2: String, keys: String*): collection.Map[String, Any] = ???

override def get(key: String): Option[Any] = ???

override def iterator: Iterator[(String, Any)] = new Iterator[(String, Any)] {
private[this] val names = stringMatrix.xs // can contain a discriminator field name at the last position
private[this] val values = buffer
private[this] var nextIdx = 0

def hasNext: Boolean = nextIdx < values.length

@inline
def next(): (String, Any) = {
val idx = nextIdx
nextIdx += 1
(names(idx), values(idx))
}
}
}).result()
}

def unsafeDecodeFields(trace: List[JsonError], in: RetractReader): Array[Any] = {
val lexer = Lexer
var continue = true
Expand Down

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