mirror of https://github.com/sbt/sbt.git
49 lines
1.2 KiB
Scala
49 lines
1.2 KiB
Scala
package sbt
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package inc
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import java.io.File
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import java.util.concurrent.ConcurrentHashMap
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sealed trait FileValueCache[T]
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{
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def clear(): Unit
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def get: File => T
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}
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private[this] final class FileValueCache0[T](getStamp: File => Stamp, make: File => T)(implicit equiv: Equiv[Stamp]) extends FileValueCache[T]
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{
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private[this] val backing = new ConcurrentHashMap[File, FileCache]
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def clear(): Unit = backing.clear()
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def get = file => {
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val ifAbsent = new FileCache(file)
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val cache = backing.putIfAbsent(file, ifAbsent)
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(if(cache eq null) ifAbsent else cache).get()
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}
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private[this] final class FileCache(file: File)
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{
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private[this] var stampedValue: Option[(Stamp,T)] = None
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def get(): T = synchronized
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{
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val latest = getStamp(file)
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stampedValue match
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{
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case Some( (stamp, value) ) if(equiv.equiv(latest, stamp)) => value
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case _ => update(latest)
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}
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}
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private[this] def update(stamp: Stamp): T =
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{
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val value = make(file)
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stampedValue = Some((stamp, value))
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value
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}
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}
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}
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object FileValueCache
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{
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def apply[T](f: File => T): FileValueCache[T] = make(Stamp.lastModified)(f)
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def make[T](stamp: File => Stamp)(f: File => T): FileValueCache[T] = new FileValueCache0[T](stamp, f)
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} |