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Kotlin Standard Library for JVM

There is a newer version: 2.1.0-RC

/*
 * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
 * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
 */

@file:kotlin.jvm.JvmMultifileClass
@file:kotlin.jvm.JvmName("StandardKt")
package kotlin

import kotlin.contracts.*
import kotlin.jvm.internal.unsafe.*

/**
 * Executes the given function [block] while holding the monitor of the given object [lock].
 */
@kotlin.internal.InlineOnly
public inline fun  synchronized(lock: Any, block: () -> R): R {
    contract {
        callsInPlace(block, InvocationKind.EXACTLY_ONCE)
    }

    // Force the lock object into a local and use that local for monitor enter/exit.
    // This ensures that the JVM can prove that locking is balanced which is a
    // prerequisite for using fast locking implementations. See KT-48367 for details.
    val lockLocal = lock

    @Suppress("NON_PUBLIC_CALL_FROM_PUBLIC_INLINE", "INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
    monitorEnter(lockLocal)
    try {
        return block()
    }
    finally {
        @Suppress("NON_PUBLIC_CALL_FROM_PUBLIC_INLINE", "INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
        monitorExit(lockLocal)
    }
}