34 lines
985 B
Kotlin
34 lines
985 B
Kotlin
package co.electriccoin.zcash.spackle
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/**
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* Implements a lazy singleton pattern with an input argument.
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*
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* This class is thread-safe.
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*/
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class LazyWithArgument<in Input, out Output>(private val deferredCreator: ((Input) -> Output)) {
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@Volatile
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private var singletonInstance: Output? = null
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private val intrinsicLock = Any()
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fun getInstance(input: Input): Output {
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/*
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* Double-checked idiom for lazy initialization, Effective Java 2nd edition page 283.
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*/
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var localSingletonInstance = singletonInstance
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if (null == localSingletonInstance) {
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synchronized(intrinsicLock) {
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localSingletonInstance = singletonInstance
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if (null == localSingletonInstance) {
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localSingletonInstance = deferredCreator(input)
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singletonInstance = localSingletonInstance
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}
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}
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}
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return localSingletonInstance!!
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}
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}
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