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perf: add rendered key byte cache in ByteRenderer #1118

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perf: add rendered key byte cache in ByteRenderer #1118

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91e43a7
perf: add rendered key byte cache in ByteRenderer
He-Pin Aug 12, 2026
67a4a30
perf: align key cache bypass threshold with populate threshold
He-Pin Aug 12, 2026
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37 changes: 36 additions & 1 deletion sjsonnet/src/sjsonnet/ByteRenderer.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,8 @@ class ByteRenderer(out: OutputStream = new java.io.ByteArrayOutputStream(), inde
private var stringValueCount = 0
private var stringValueCacheKeys: Array[String] = null
private var stringValueCacheBytes: Array[Array[Byte]] = null
private var keyCacheKeys: Array[String] = null
private var keyCacheBytes: Array[Array[Byte]] = null

override def visitFloat64(d: Double, index: Int): OutputStream = {
flushBuffer()
Expand Down Expand Up @@ -320,12 +322,42 @@ class ByteRenderer(out: OutputStream = new java.io.ByteArrayOutputStream(), inde
ctx: Materializer.MaterializeContext)(implicit evaluator: EvalScope): Unit = {
markNonEmpty()
flushBuffer()
renderQuotedString(key)
renderCachedKey(key)
elemBuilder.append(':')
elemBuilder.append(' ')
materializeChild(childVal, matDepth, ctx)
}

@inline private def renderCachedKey(key: String): Unit = {
if (key.length > ByteRenderer.KeyCacheMaxKeyLength) {
renderQuotedString(key)
return
}
var cacheKeys = keyCacheKeys
var cacheBytes = keyCacheBytes
if (cacheKeys == null) {
cacheKeys = new Array[String](ByteRenderer.KeyCacheSize)
cacheBytes = new Array[Array[Byte]](ByteRenderer.KeyCacheSize)
keyCacheKeys = cacheKeys
keyCacheBytes = cacheBytes
}
val slot = System.identityHashCode(key) & ByteRenderer.KeyCacheMask
if (cacheKeys(slot) eq key) {
val bytes = cacheBytes(slot)
if (bytes != null) {
appendCachedStringBytes(bytes)
return
}
}
val startLen = elemBuilder.length
renderQuotedString(key)
val rendered = elemBuilder.length - startLen
val bytes = new Array[Byte](rendered)
System.arraycopy(elemBuilder.arr, startLen, bytes, 0, rendered)
cacheKeys(slot) = key
cacheBytes(slot) = bytes
}

private def renderAsciiSafeValueString(str: String): Unit = {
val len = str.length
if (
Expand Down Expand Up @@ -574,4 +606,7 @@ object ByteRenderer {
private final val StringValueCacheSize = 32
private final val StringValueCacheMask = StringValueCacheSize - 1
private final val DirectCachedStringWriteMinLength = 1024
private final val KeyCacheSize = 64
private final val KeyCacheMask = KeyCacheSize - 1
private final val KeyCacheMaxKeyLength = 32
}
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