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/*
* Copyright 2017-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
*/
package kotlinx.serialization.json.internal
import kotlinx.serialization.descriptors.*
import kotlin.native.concurrent.*
private typealias DescriptorData<T> = MutableMap<DescriptorSchemaCache.Key<T>, T>
/**
* A type-safe map for storing custom information (such as format schema), associated with [SerialDescriptor].
*
* This cache uses ConcurrentHashMap on JVM and regular maps on other platforms.
* To be able to work with it from multiple threads in Kotlin/Native, use @[ThreadLocal] in appropriate places.
*/
internal class DescriptorSchemaCache {
// 16 is default CHM size, as we do not know number of descriptors in an application (but it's likely not 1)
private val map: MutableMap<SerialDescriptor, DescriptorData<Any>> = createMapForCache(16)
@Suppress("UNCHECKED_CAST")
public operator fun <T : Any> set(descriptor: SerialDescriptor, key: Key<T>, value: T) {
// Initial capacity = number of known DescriptorSchemaCache.Key instances
map.getOrPut(descriptor, { createMapForCache(2) })[key as Key<Any>] = value as Any
}
public fun <T : Any> getOrPut(descriptor: SerialDescriptor, key: Key<T>, defaultValue: () -> T): T {
get(descriptor, key)?.let { return it }
val value = defaultValue()
set(descriptor, key, value)
return value
}
@Suppress("UNCHECKED_CAST")
public operator fun <T : Any> get(descriptor: SerialDescriptor, key: Key<T>): T? {
return map[descriptor]?.get(key as Key<Any>) as? T
}
/**
* A key for associating user data of type [T] with a given [SerialDescriptor].
*/
public class Key<T : Any> {}
}
/**
* Creates a ConcurrentHashMap on JVM and regular HashMap on other platforms.
* To make actual use of cache in Kotlin/Native, mark a top-level object with this map
* as a @[ThreadLocal].
*/
internal expect fun <K, V> createMapForCache(initialCapacity: Int): MutableMap<K, V>
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