KTOR-4809 Add Flag to disable CharArray pooling (#3153)

ktor-http/ktor-http-cio/common/src/io/ktor/http/cio/internals/CharArrayPool.kt

@@ -6,13 +6,23 @@ package io.ktor.http.cio.internals
 
 import io.ktor.utils.io.pool.*
 
+internal expect val DISABLE_CHAR_ARRAY_POOLING: Boolean
+
 internal const val CHAR_ARRAY_POOL_SIZE = 4096
 
 /**
  * Number of characters that an array from the pool can store
  */
 internal const val CHAR_BUFFER_ARRAY_LENGTH: Int = 4096 / 2
 
-internal val CharArrayPool: ObjectPool<CharArray> = object : DefaultPool<CharArray>(CHAR_ARRAY_POOL_SIZE) {
-    override fun produceInstance(): CharArray = CharArray(CHAR_BUFFER_ARRAY_LENGTH)
+internal val CharArrayPool: ObjectPool<CharArray> = if (DISABLE_CHAR_ARRAY_POOLING) {
+    object : NoPoolImpl<CharArray>() {
+        override fun borrow(): CharArray {
+            return CharArray(CHAR_BUFFER_ARRAY_LENGTH)
+        }
+    }
+} else {
+    object : DefaultPool<CharArray>(CHAR_ARRAY_POOL_SIZE) {
+        override fun produceInstance(): CharArray = CharArray(CHAR_BUFFER_ARRAY_LENGTH)
+    }
 }

ktor-http/ktor-http-cio/js/src/io/ktor/http/cio/internals/CharArrayPoolJs.kt

@@ -0,0 +1,7 @@
+/*
+ * Copyright 2014-2022 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package io.ktor.http.cio.internals
+
+internal actual val DISABLE_CHAR_ARRAY_POOLING: Boolean = false

ktor-http/ktor-http-cio/jvm/src/io/ktor/http/cio/internals/CharArrayPoolJvm.kt

@@ -0,0 +1,8 @@
+/*
+ * Copyright 2014-2022 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package io.ktor.http.cio.internals
+
+internal actual val DISABLE_CHAR_ARRAY_POOLING: Boolean =
+    System.getProperty("ktor.internal.cio.disable.chararray.pooling")?.toBoolean() ?: false

ktor-http/ktor-http-cio/posix/src/io/ktor/http/cio/internals/CharArrayPoolPosix.kt

@@ -0,0 +1,7 @@
+/*
+ * Copyright 2014-2022 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package io.ktor.http.cio.internals
+
+internal actual val DISABLE_CHAR_ARRAY_POOLING: Boolean = false

ktor-io/jvm/src/io/ktor/utils/io/pool/DefaultPool.kt

@@ -25,7 +25,7 @@ actual constructor(actual final override val capacity: Int) : ObjectPool<T> {
     // factory
     protected actual abstract fun produceInstance(): T
 
-    // optional cleaning of poped items
+    // optional cleaning of popped items
     protected actual open fun clearInstance(instance: T): T = instance
 
     // optional validation for recycled items