/* =========================================================================================
* Copyright © 2013-2018 the kamon project
It is faster to use a mutable holder object and always perform ThreadLocal.get() and never use * ThreadLocal.set(), because the value is more likely to be found in the ThreadLocalMap direct hash * slot and avoid the slow path ThreadLocalMap.getEntryAfterMiss(). * *
Credit to @trask from the FastThreadLocal in glowroot. * *
One small change is that we don't use an kamon-defined holder object as that would prevent class unloading. * * */ class ThreadLocal extends Storage { private val tls = new java.lang.ThreadLocal[Array[AnyRef]]() { override def initialValue(): Array[AnyRef] = Array(Context.Empty) } override def current(): Context = tls.get()(0).asInstanceOf[Context] override def store(newContext: Context): Scope = { val ref = tls.get() val previousContext = ref(0) ref(0) = newContext new Scope { override def context: Context = newContext override def close(): Unit = ref(0) = previousContext } } } object ThreadLocal { def apply(): ThreadLocal = new ThreadLocal() } }