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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,95 @@ | ||
| package com.juul.tuulbox.collections | ||
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| import kotlinx.collections.immutable.ImmutableCollection | ||
| import kotlinx.collections.immutable.ImmutableMap | ||
| import kotlinx.collections.immutable.ImmutableSet | ||
| import kotlinx.collections.immutable.PersistentMap | ||
| import kotlinx.collections.immutable.mutate | ||
| import kotlinx.collections.immutable.persistentHashMapOf | ||
| import kotlinx.collections.immutable.persistentMapOf | ||
| import kotlinx.coroutines.flow.MutableStateFlow | ||
| import kotlinx.coroutines.flow.StateFlow | ||
| import kotlinx.coroutines.flow.asStateFlow | ||
| import kotlinx.coroutines.flow.getAndUpdate | ||
| import kotlinx.coroutines.flow.update | ||
| import kotlinx.coroutines.flow.updateAndGet | ||
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| /** Returns an [AtomicMap] that guarantees preservation of iteration order, but may be slower. */ | ||
| public fun <K, V> atomicMapOf( | ||
| vararg pairs: Pair<K, V>, | ||
| ): AtomicMap<K, V> = AtomicMap(persistentMapOf(*pairs)) | ||
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| /** Returns an [AtomicMap] that does not guarantee preservation of iteration order, but may be faster. */ | ||
| public fun <K, V> atomicHashMapOf( | ||
| vararg pairs: Pair<K, V>, | ||
| ): AtomicMap<K, V> = AtomicMap(persistentHashMapOf(*pairs)) | ||
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| /** | ||
| * A [Map] that allows for thread safe, atomic mutation. Returned collections such as [entries] and | ||
| * [iterator] reference a [snapshot] of when they were accessed, and are not mutated when the map is. | ||
| * | ||
| * Although mutable, this class intentionally does not implement [MutableMap]. Mutation must use | ||
| * designated mutator functions ([mutate], [snapshotAndMutate], [mutateAndSnapshot]). | ||
| */ | ||
| public class AtomicMap<K, V> private constructor( | ||
| @PublishedApi | ||
| internal val state: MutableStateFlow<PersistentMap<K, V>>, | ||
| ) : Map<K, V> { | ||
|
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| /** Construct an [AtomicMap] with [initial] mappings. */ | ||
| public constructor(initial: PersistentMap<K, V>) : this(MutableStateFlow(initial)) | ||
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| /** Returns this map as a [StateFlow]. Each mutation will cause a new emission on this flow. */ | ||
| public val snapshots: StateFlow<ImmutableMap<K, V>> = state.asStateFlow() | ||
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| /** | ||
| * Returns the current value of this map as an [immutable][ImmutableMap] snapshot. | ||
| * | ||
| * This operation is non-copying and efficient. | ||
| */ | ||
| public val snapshot: ImmutableMap<K, V> | ||
| get() = snapshots.value | ||
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| override val size: Int | ||
| get() = snapshot.size | ||
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| override val entries: ImmutableSet<Map.Entry<K, V>> | ||
| get() = snapshot.entries | ||
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| override val keys: ImmutableSet<K> | ||
| get() = snapshot.keys | ||
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| override val values: ImmutableCollection<V> | ||
| get() = snapshot.values | ||
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| override fun containsKey(key: K): Boolean = snapshot.containsKey(key) | ||
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| override fun containsValue(value: V): Boolean = snapshot.containsValue(value) | ||
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| override fun get(key: K): V? = snapshot[key] | ||
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| override fun isEmpty(): Boolean = snapshot.isEmpty() | ||
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| override fun equals(other: Any?): Boolean = snapshot == other | ||
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| override fun hashCode(): Int = snapshot.hashCode() | ||
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| override fun toString(): String = snapshot.toString() | ||
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| /** Mutates this map atomically. [mutator] can be evaluated multiple times if a concurrent edit occurs. */ | ||
| public inline fun mutate(mutator: MutableMap<K, V>.() -> Unit) { | ||
| state.update { it.mutate(mutator) } | ||
| } | ||
|
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| /** Mutates this map atomically and returns the previous [snapshot]. [mutator] can be evaluated multiple times if a concurrent edit occurs. */ | ||
| public inline fun snapshotAndMutate(mutator: MutableMap<K, V>.() -> Unit): ImmutableMap<K, V> = | ||
| state.getAndUpdate { it.mutate(mutator) } | ||
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| /** Mutates this map atomically and returns the new [snapshot]. [mutator] can be evaluated multiple times if a concurrent edit occurs. */ | ||
| public inline fun mutateAndSnapshot(mutator: MutableMap<K, V>.() -> Unit): ImmutableMap<K, V> = | ||
| state.updateAndGet { it.mutate(mutator) } | ||
| } | ||
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| /** Atomic version of [MutableMap.getOrPut]. [defaultValue] can be evaluated multiple times if a concurrent edit occurs. */ | ||
| public inline fun <K, V> AtomicMap<K, V>.getOrPut(key: K, defaultValue: () -> V): V = | ||
| mutateAndSnapshot { getOrPut(key, defaultValue) }.getValue(key) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,44 @@ | ||
| package com.juul.tuulbox.collections | ||
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| import kotlinx.collections.immutable.persistentMapOf | ||
| import kotlinx.coroutines.Dispatchers | ||
| import kotlinx.coroutines.joinAll | ||
| import kotlinx.coroutines.launch | ||
| import kotlinx.coroutines.test.runTest | ||
| import kotlin.test.Test | ||
| import kotlin.test.assertEquals | ||
|
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| public class AtomicMapTests { | ||
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| @Test | ||
| public fun atomicMap_concurrentMutateBlocks_doesNotLoseWrites() = runTest { | ||
| val actual = AtomicMap<String, Int>(persistentMapOf()) | ||
| (1..10).map { | ||
| launch(Dispatchers.Default) { | ||
| for (i in 0 until 500) { | ||
| actual.mutate { this["count"] = (this["count"] ?: 0) + 1 } | ||
| } | ||
| } | ||
| }.joinAll() | ||
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| assertEquals(mapOf("count" to 5_000), actual) | ||
| } | ||
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| @Test | ||
| public fun atomicMap_snapshotAndMutate_returnsPreviousSnapshot() = runTest { | ||
| val atomic = AtomicMap<Int, Int>(persistentMapOf()) | ||
| val actual = atomic.snapshotAndMutate { | ||
| put(0, 0) | ||
| } | ||
| assertEquals(emptyMap(), actual) | ||
| } | ||
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| @Test | ||
| public fun atomicMap_mutateAndSnapshot_returnsNewSnapshot() = runTest { | ||
| val atomic = AtomicMap<Int, Int>(persistentMapOf()) | ||
| val actual = atomic.mutateAndSnapshot { | ||
| put(0, 0) | ||
| } | ||
| assertEquals(mapOf(0 to 0), actual) | ||
| } | ||
| } |
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