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author | cremet <cremet@epfl.ch> | 2003-08-26 15:28:51 +0000 |
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committer | cremet <cremet@epfl.ch> | 2003-08-26 15:28:51 +0000 |
commit | 80d3a625a75ba054eef58eac94dc3a8066690c36 (patch) | |
tree | ccdc5d3d86415b7630666961d2741589cf59dede /sources/examples/pilib/semaphore.scala | |
parent | 4c10e8515b2d1b7991f660b444f4b0a5d014286d (diff) | |
download | scala-80d3a625a75ba054eef58eac94dc3a8066690c36.tar.gz scala-80d3a625a75ba054eef58eac94dc3a8066690c36.tar.bz2 scala-80d3a625a75ba054eef58eac94dc3a8066690c36.zip |
- Added "PiLib" library and associated examples.
- Fixed some files in the package "scala.concurrent".
Diffstat (limited to 'sources/examples/pilib/semaphore.scala')
-rw-r--r-- | sources/examples/pilib/semaphore.scala | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/sources/examples/pilib/semaphore.scala b/sources/examples/pilib/semaphore.scala new file mode 100644 index 0000000000..f1f454e239 --- /dev/null +++ b/sources/examples/pilib/semaphore.scala @@ -0,0 +1,70 @@ +/** 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(def 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") + } ) + } >; + } +} + |