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Mark Harrah
907e84b027
Construction of Scala providers was already properly synchronized jvm and machine-wide. The cache on top of construction was not. This could cause the same Scala version to be loaded in multiple class loaders.
23 lines
780 B
Scala
23 lines
780 B
Scala
/* sbt -- Simple Build Tool
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* Copyright 2009, 2010 Mark Harrah
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*/
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package xsbt.boot
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import java.lang.ref.{Reference, SoftReference}
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import java.util.HashMap
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final class Cache[K,X,V](create: (K,X) => V)
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{
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private[this] val delegate = new HashMap[K,Reference[V]]
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def apply(k: K, x: X): V = synchronized { getFromReference(k, x, delegate.get(k)) }
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private[this] def getFromReference(k: K, x: X, existingRef: Reference[V]) = if(existingRef eq null) newEntry(k, x) else get(k, x, existingRef.get)
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private[this] def get(k: K, x: X, existing: V) = if(existing == null) newEntry(k, x) else existing
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private[this] def newEntry(k: K, x: X): V =
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{
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val v = create(k, x)
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Pre.assert(v != null, "Value for key " + k + " was null")
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delegate.put(k, new SoftReference(v))
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v
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}
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}
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