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author | Gilles Dubochet <gilles.dubochet@epfl.ch> | 2005-12-16 18:44:33 +0000 |
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committer | Gilles Dubochet <gilles.dubochet@epfl.ch> | 2005-12-16 18:44:33 +0000 |
commit | 53a3cc7b17f4cf97075b7e71720777fd84109696 (patch) | |
tree | 0cc784e0b47ea49cc151a136d19f20bfa8ee2197 /docs/examples/pilib/semaphore.scala | |
parent | df50e05006b43b007c2587549030d24b5c154398 (diff) | |
download | scala-53a3cc7b17f4cf97075b7e71720777fd84109696.tar.gz scala-53a3cc7b17f4cf97075b7e71720777fd84109696.tar.bz2 scala-53a3cc7b17f4cf97075b7e71720777fd84109696.zip |
Created proper 'docs' folder for new layout.
Diffstat (limited to 'docs/examples/pilib/semaphore.scala')
-rw-r--r-- | docs/examples/pilib/semaphore.scala | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/docs/examples/pilib/semaphore.scala b/docs/examples/pilib/semaphore.scala new file mode 100644 index 0000000000..cfb0c8e5a2 --- /dev/null +++ b/docs/examples/pilib/semaphore.scala @@ -0,0 +1,72 @@ +package examples.pilib; + +/** Solution of exercise session 6 (first question). */ +object semaphore { + + import scala.concurrent.pilib._; + + class Signal extends Chan[unit] { + def send = write(()); + def receive = read; + } + + /** Interface. */ + trait Semaphore { + def get: unit; + def release: unit; + } + + /** First implementation. */ + class Sem1 extends Semaphore { + + private val g = new Signal; + private val r = new Signal; + + def get: unit = g.send; + def release: unit = r.send; + + private def Sched: unit = choice ( + g * (x => { r.receive; Sched }), + r * (x => Sched) + ); + spawn< Sched >; + } + + /** Second implementation. */ + class Sem2 extends Semaphore { + + private val a = new Signal; + private val na = new Signal; + + def get: unit = { a.receive; spawn< na.send > } + def release: unit = choice ( + a * (x => spawn< a.send >), + na * (x => spawn< a.send >) + ); + spawn< a.send >; + } + + /** Test program. */ + def main(args: Array[String]): unit = { + val random = new java.util.Random(); + val sem = new Sem2; + def mutex(p: => unit): unit = { sem.get; p; sem.release } + + spawn< { + Thread.sleep(1 + random.nextInt(100)); + mutex( { + System.out.println("a1"); + Thread.sleep(1 + random.nextInt(100)); + System.out.println("a2") + } ) + } | { + Thread.sleep(1 + random.nextInt(100)); + mutex( { + System.out.println("b1"); + Thread.sleep(1 + random.nextInt(100)); + System.out.println("b2") + } ) + } >; + } +} + |