Mitigate unnecessary Encoder.OutFeed allocation when array is empty (#227)

Author: 05nelsonm

benchmarks/README.md

@@ -15,11 +15,6 @@ workflow run on the [GitHub Actions][url-actions] tab of the repository.
   ./gradlew jvmBenchmark
   ```
 
-- Run Js:
-  ```shell
-  ./gradlew jsBenchmark
-  ```
-
 - Run WasmJs:
   ```shell
   ./gradlew wasmJsBenchmark

library/core/src/commonMain/kotlin/io/matthewnelson/encoding/core/Encoder.kt

@@ -221,7 +221,7 @@ public sealed class Encoder<C: EncoderDecoder.Config>(config: C): Decoder<C>(con
         public fun ByteArray.encodeToString(encoder: Encoder<*>): String {
             return encoder.encodeOutMaxSizeOrFail(size) { maxSize ->
                 val sb = StringBuilder(maxSize)
-                encoder.encode(this, sb::append)
+                encoder.encode(this, _outFeed = { OutFeed(sb::append) })
                 val result = sb.toString()
                 if (encoder.config.backFillBuffers) {
                     sb.wipe()
@@ -248,7 +248,7 @@ public sealed class Encoder<C: EncoderDecoder.Config>(config: C): Decoder<C>(con
             return encoder.encodeOutMaxSizeOrFail(size) block@ { maxSize ->
                 var i = 0
                 val a = CharArray(maxSize)
-                encoder.encode(this) { c -> a[i++] = c }
+                encoder.encode(this, _outFeed = { OutFeed { c -> a[i++] = c } })
                 if (i == maxSize) return@block a
                 val copy = a.copyOf(i)
                 if (encoder.config.backFillBuffers) {
@@ -274,7 +274,7 @@ public sealed class Encoder<C: EncoderDecoder.Config>(config: C): Decoder<C>(con
             return encoder.encodeOutMaxSizeOrFail(size) block@ { maxSize ->
                 var i = 0
                 val a = ByteArray(maxSize)
-                encoder.encode(this) { char -> a[i++] = char.code.toByte() }
+                encoder.encode(this, _outFeed = { OutFeed { char -> a[i++] = char.code.toByte() } })
                 if (i == maxSize) return@block a
                 val copy = a.copyOf(i)
                 if (encoder.config.backFillBuffers) {

library/core/src/commonMain/kotlin/io/matthewnelson/encoding/core/EncoderDecoder.kt

@@ -807,6 +807,6 @@ private inline fun checkMaxEmitSize(size: Int, parameterName: () -> String) {
 }
 
 @Suppress("NOTHING_TO_INLINE")
-internal inline fun negativeEncodingSizeException(outSize: Number): EncodingSizeException {
+private inline fun negativeEncodingSizeException(outSize: Number): EncodingSizeException {
     return EncodingSizeException("Calculated output of Size[$outSize] was negative")
 }

library/core/src/commonMain/kotlin/io/matthewnelson/encoding/core/internal/-Encoder.kt

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  **/
-@file:Suppress("LocalVariableName", "NOTHING_TO_INLINE")
+@file:Suppress("LocalVariableName")
 
 package io.matthewnelson.encoding.core.internal
 
@@ -37,19 +37,20 @@ internal inline fun <T: Any> Encoder<*>.encodeOutMaxSizeOrFail(
     _block: (maxSize: Int) -> T,
 ): T {
     contract { callsInPlace(_block, InvocationKind.AT_MOST_ONCE) }
-
     val maxSize = config.encodeOutMaxSize(size.toLong())
     if (maxSize > MAX_ENCODE_OUT_SIZE) {
         throw Config.outSizeExceedsMaxEncodingSizeException(maxSize, MAX_ENCODE_OUT_SIZE)
     }
-
     return _block(maxSize.toInt())
 }
 
+@OptIn(ExperimentalContracts::class)
 internal inline fun <C: Config> Encoder<C>.encode(
     data: ByteArray,
-    out: Encoder.OutFeed,
+    _outFeed: () -> Encoder.OutFeed,
 ) {
+    contract { callsInPlace(_outFeed, InvocationKind.AT_MOST_ONCE) }
     if (data.isEmpty()) return
+    val out = _outFeed()
     newEncoderFeed(out).use { feed -> data.forEach { b -> feed.consume(b) } }
 }