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Standard library for the Scala Programming Language
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala
package sys
package process
import processInternal._
import java.io.{ PipedInputStream, PipedOutputStream }
private[process] trait ProcessImpl {
self: Process.type =>
/** Runs provided code in a new Thread and returns the Thread instance. */
private[process] object Spawn {
def apply(f: => Unit): Thread = apply(f, daemon = false)
def apply(f: => Unit, daemon: Boolean): Thread = {
val thread = new Thread() { override def run() = { f } }
thread.setDaemon(daemon)
thread.start()
thread
}
}
private[process] object Future {
def apply[T](f: => T): (Thread, () => T) = {
val result = new SyncVar[Either[Throwable, T]]
def run(): Unit =
try result.put(Right(f))
catch { case e: Exception => result.put(Left(e)) }
val t = Spawn(run())
(t, () => result.get match {
case Right(value) => value
case Left(exception) => throw exception
})
}
}
private[process] class AndProcess(
a: ProcessBuilder,
b: ProcessBuilder,
io: ProcessIO
) extends SequentialProcess(a, b, io, _ == 0)
private[process] class OrProcess(
a: ProcessBuilder,
b: ProcessBuilder,
io: ProcessIO
) extends SequentialProcess(a, b, io, _ != 0)
private[process] class ProcessSequence(
a: ProcessBuilder,
b: ProcessBuilder,
io: ProcessIO
) extends SequentialProcess(a, b, io, _ => true)
private[process] class SequentialProcess(
a: ProcessBuilder,
b: ProcessBuilder,
io: ProcessIO,
evaluateSecondProcess: Int => Boolean
) extends CompoundProcess {
protected[this] override def runAndExitValue() = {
val first = a.run(io)
runInterruptible(first.exitValue())(first.destroy()) flatMap { codeA =>
if (evaluateSecondProcess(codeA)) {
val second = b.run(io)
runInterruptible(second.exitValue())(second.destroy())
}
else Some(codeA)
}
}
}
private[process] abstract class BasicProcess extends Process {
def start(): Unit
}
private[process] abstract class CompoundProcess extends BasicProcess {
def isAlive() = processThread.isAlive()
def destroy() = destroyer()
def exitValue() = futureValue() getOrElse scala.sys.error("No exit code: process destroyed.")
def start() = { futureThread ;() }
protected lazy val (processThread, (futureThread, futureValue), destroyer) = {
val code = new SyncVar[Option[Int]]()
val thread = Spawn {
var value: Option[Int] = None
try value = runAndExitValue()
finally code.put(value)
}
(
thread,
Future(code.get), // thread.join()
() => thread.interrupt()
)
}
/** Start and block until the exit value is available and then return it in Some. Return None if destroyed (use 'run')*/
protected[this] def runAndExitValue(): Option[Int]
protected[this] def runInterruptible[T](action: => T)(destroyImpl: => Unit): Option[T] = {
try Some(action)
catch onInterrupt { destroyImpl; None }
}
}
private[process] class PipedProcesses(a: ProcessBuilder, b: ProcessBuilder, defaultIO: ProcessIO, toError: Boolean) extends CompoundProcess {
protected[this] override def runAndExitValue() = runAndExitValue(new PipeSource(a.toString), new PipeSink(b.toString))
protected[this] def runAndExitValue(source: PipeSource, sink: PipeSink): Option[Int] = {
source connectOut sink
source.start()
sink.start()
/** Release PipeSource, PipeSink and Process in the correct order.
* If once connect Process with Source or Sink, then the order of releasing them
* must be Source -> Sink -> Process, otherwise IOException will be thrown. */
def releaseResources(so: PipeSource, sk: PipeSink, p: Process *) = {
so.release()
sk.release()
p foreach( _.destroy() )
}
val firstIO =
if (toError) defaultIO.withError(source.connectIn)
else defaultIO.withOutput(source.connectIn)
val secondIO = defaultIO.withInput(sink.connectOut)
val second =
try b.run(secondIO)
catch onError { err =>
releaseResources(source, sink)
throw err
}
val first =
try a.run(firstIO)
catch onError { err =>
releaseResources(source, sink, second)
throw err
}
runInterruptible {
source.join()
val exit1 = first.exitValue()
val exit2 = second.exitValue()
// Since file redirection (e.g. #>) is implemented as a piped process,
// we ignore its exit value so cmd #> file doesn't always return 0.
if (b.hasExitValue) exit2 else exit1
} {
releaseResources(source, sink, first, second)
}
}
}
private[process] abstract class PipeThread(isSink: Boolean, labelFn: () => String) extends Thread {
def run(): Unit
private[process] def runloop(src: InputStream, dst: OutputStream): Unit = {
try BasicIO.transferFully(src, dst)
catch ioFailure(ioHandler)
finally BasicIO close {
if (isSink) dst else src
}
}
private def ioHandler(e: IOException) {
println("I/O error " + e.getMessage + " for process: " + labelFn())
e.printStackTrace()
}
}
private[process] class PipeSource(label: => String) extends PipeThread(false, () => label) {
protected[this] val pipe = new PipedOutputStream
protected[this] val source = new LinkedBlockingQueue[Option[InputStream]]
override def run(): Unit = {
try {
source.take match {
case Some(in) => runloop(in, pipe)
case None =>
}
}
catch onInterrupt(())
finally BasicIO close pipe
}
def connectIn(in: InputStream): Unit = source add Some(in)
def connectOut(sink: PipeSink): Unit = sink connectIn pipe
def release(): Unit = {
interrupt()
source add None
join()
}
}
private[process] class PipeSink(label: => String) extends PipeThread(true, () => label) {
protected[this] val pipe = new PipedInputStream
protected[this] val sink = new LinkedBlockingQueue[Option[OutputStream]]
override def run(): Unit = {
try {
sink.take match {
case Some(out) => runloop(pipe, out)
case None =>
}
}
catch onInterrupt(())
finally BasicIO close pipe
}
def connectOut(out: OutputStream): Unit = sink add Some(out)
def connectIn(pipeOut: PipedOutputStream): Unit = pipe connect pipeOut
def release(): Unit = {
interrupt()
sink add None
join()
}
}
/** A thin wrapper around a java.lang.Process. `ioThreads` are the Threads created to do I/O.
* The implementation of `exitValue` waits until these threads die before returning.
*/
private[process] class DummyProcess(action: => Int) extends Process {
private[this] val (thread, value) = Future(action)
override def isAlive() = thread.isAlive()
override def exitValue() = value()
override def destroy() { }
}
/** A thin wrapper around a java.lang.Process. `outputThreads` are the Threads created to read from the
* output and error streams of the process. `inputThread` is the Thread created to write to the input stream of
* the process.
* The implementation of `exitValue` interrupts `inputThread` and then waits until all I/O threads die before
* returning. */
private[process] class SimpleProcess(p: JProcess, inputThread: Thread, outputThreads: List[Thread]) extends Process {
override def isAlive() = p.isAlive()
override def exitValue() = {
try p.waitFor() // wait for the process to terminate
finally inputThread.interrupt() // we interrupt the input thread to notify it that it can terminate
outputThreads foreach (_.join()) // this ensures that all output is complete before returning (waitFor does not ensure this)
p.exitValue()
}
override def destroy() = {
try {
outputThreads foreach (_.interrupt()) // on destroy, don't bother consuming any more output
p.destroy()
}
finally inputThread.interrupt()
}
}
private[process] final class ThreadProcess(thread: Thread, success: SyncVar[Boolean]) extends Process {
override def isAlive() = thread.isAlive()
override def exitValue() = if (success.get) 0 else 1 // thread.join()
override def destroy() = thread.interrupt()
}
}