scala.sys.package.scala Maven / Gradle / Ivy
/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala
import scala.collection.immutable.ArraySeq
import scala.jdk.CollectionConverters._
/** The package object `scala.sys` contains methods for reading
* and altering core aspects of the virtual machine as well as the
* world outside of it.
*/
package object sys {
/** Throw a new RuntimeException with the supplied message.
*
* @return Nothing.
*/
def error(message: String): Nothing = throw new RuntimeException(message)
/** Exit the JVM with the default status code.
*
* @return Nothing.
*/
def exit(): Nothing = exit(0)
/** Exit the JVM with the given status code.
*
* @return Nothing.
*/
def exit(status: Int): Nothing = {
java.lang.System.exit(status)
throw new Throwable()
}
/** A convenience method to get the current Runtime instance.
*
* @return the result of `java.lang.Runtime.getRuntime()`
*/
def runtime: Runtime = Runtime.getRuntime
/** A bidirectional, mutable Map representing the current system Properties.
*
* @return a SystemProperties.
* @see [[scala.sys.SystemProperties]]
*/
def props: SystemProperties = new SystemProperties
// TODO: consider whether layering a Map on top of Java's properties is really needed -- we could simply provide:
// def prop(p: String) = Option(System.getProperty(p))
/** An immutable Map representing the current system environment.
*
* If lookup fails, use `System.getenv(_)` for case-insensitive lookup
* on a certain platform. If that also fails, throw `NoSuchElementException`.
*
* @return a Map containing the system environment variables.
*/
def env: Map[String, String] = Map.from(System.getenv().asScala).withDefault { v =>
val s = System.getenv(v)
if (s == null) throw new NoSuchElementException(v)
s
}
/** Register a shutdown hook to be run when the VM exits.
* The hook is automatically registered: the returned value can be ignored,
* but is available in case the Thread requires further modification.
* It can also be unregistered by calling ShutdownHookThread#remove().
*
* Note that shutdown hooks are NOT guaranteed to be run.
*
* @param body the body of code to run at shutdown
* @return the Thread which will run the shutdown hook.
* @see [[scala.sys.ShutdownHookThread]]
*/
def addShutdownHook(body: => Unit): ShutdownHookThread = ShutdownHookThread(body)
/** Returns all active thread in the current thread's thread group and subgroups.
*
* @return an IndexedSeq containing the threads.
*/
def allThreads(): IndexedSeq[Thread] = {
val num = Thread.activeCount()
val tarray = new Array[Thread](num)
val got = Thread.enumerate(tarray)
ArraySeq.unsafeWrapArray(tarray).take(got)
}
}