1 files changed, 89 insertions, 0 deletions
diff --git a/formats/json/jvmMain/src/kotlinx/serialization/json/internal/ArrayPools.kt b/formats/json/jvmMain/src/kotlinx/serialization/json/internal/ArrayPools.kt
new file mode 100644
index 00000000..0d36c6c0
--- /dev/null
+++ b/formats/json/jvmMain/src/kotlinx/serialization/json/internal/ArrayPools.kt
@@ -0,0 +1,89 @@
+/*
+ * Copyright 2017-2022 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+package kotlinx.serialization.json.internal
+
+/*
+ * Not really documented kill switch as a workaround for potential
+ * (unlikely) problems with memory consumptions.
+ */
+private val MAX_CHARS_IN_POOL = runCatching {
+    System.getProperty("kotlinx.serialization.json.pool.size").toIntOrNull()
+}.getOrNull() ?: 2 * 1024 * 1024
+
+internal open class CharArrayPoolBase {
+    private val arrays = ArrayDeque<CharArray>()
+    private var charsTotal = 0
+
+    protected fun take(size: Int): CharArray {
+        /*
+         * Initially the pool is empty, so an instance will be allocated
+         * and the pool will be populated in the 'release'
+         */
+        val candidate = synchronized(this) {
+            arrays.removeLastOrNull()?.also { charsTotal -= it.size }
+        }
+        return candidate ?: CharArray(size)
+    }
+
+    protected fun releaseImpl(array: CharArray): Unit = synchronized(this) {
+        if (charsTotal + array.size >= MAX_CHARS_IN_POOL) return@synchronized
+        charsTotal += array.size
+        arrays.addLast(array)
+    }
+}
+
+internal object CharArrayPool : CharArrayPoolBase() {
+    fun take(): CharArray = super.take(128)
+
+    // Can release array of an arbitrary size
+    fun release(array: CharArray) = releaseImpl(array)
+}
+
+// Pools char arrays of size 16K
+internal actual object CharArrayPoolBatchSize : CharArrayPoolBase() {
+
+    actual fun take(): CharArray = super.take(BATCH_SIZE)
+
+    actual fun release(array: CharArray) {
+        require(array.size == BATCH_SIZE) { "Inconsistent internal invariant: unexpected array size ${array.size}" }
+        releaseImpl(array)
+    }
+}
+
+// Byte array pool
+
+internal open class ByteArrayPoolBase {
+    private val arrays = ArrayDeque<kotlin.ByteArray>()
+    private var bytesTotal = 0
+
+    protected fun take(size: Int): ByteArray {
+        /*
+         * Initially the pool is empty, so an instance will be allocated
+         * and the pool will be populated in the 'release'
+         */
+        val candidate = synchronized(this) {
+            arrays.removeLastOrNull()?.also { bytesTotal -= it.size / 2 }
+        }
+        return candidate ?: ByteArray(size)
+    }
+
+    protected fun releaseImpl(array: ByteArray): Unit = synchronized(this) {
+        if (bytesTotal + array.size >= MAX_CHARS_IN_POOL) return@synchronized
+        bytesTotal += array.size / 2
+        arrays.addLast(array)
+    }
+}
+
+internal object ByteArrayPool8k : ByteArrayPoolBase() {
+    fun take(): ByteArray = super.take(8196)
+
+    fun release(array: ByteArray) = releaseImpl(array)
+}
+
+
+internal object ByteArrayPool : ByteArrayPoolBase() {
+    fun take(): ByteArray = super.take(512)
+
+    fun release(array: ByteArray) = releaseImpl(array)
+}