- Added "PiLib" library and associated examples.

- Fixed some files in the package "scala.concurrent".

1 files changed, 147 insertions, 0 deletions

diff --git a/sources/examples/pilib/scheduler.scala b/sources/examples/pilib/scheduler.scala
new file mode 100644
index 0000000000..ca377ddcf6
--- /dev/null
+++ b/sources/examples/pilib/scheduler.scala
@@ -0,0 +1,147 @@
+object scheduler {
+
+  import scala.concurrent.pilib._;
+
+  /**
+  * Random number generator.
+  */
+  val random = new java.util.Random();
+
+  //***************** Scheduler ******************//
+
+  /**
+  * A cell of the scheduler whose attached agent is allowed to start.
+  */
+  def A(a: Chan[unit], b: Chan[unit])(d: Chan[unit], c: Chan[unit]): unit = {
+    a.read;
+    C(a,b)(d,c)
+  }
+
+  /**
+  * A cell of the scheduler in an intermediate state (incorrect)
+  */
+//   def B(a: Chan[unit], b: Chan[unit])(d: Chan[unit], c: Chan[unit]): unit = {
+//     b.read;
+//     D(a,b)(d,c)
+//   }
+
+  /**
+  * A cell of the scheduler in an intermediate state (correct).
+  */
+  def B(a: Chan[unit], b: Chan[unit])(d: Chan[unit], c: Chan[unit]): unit =
+    choice (
+      b * (x => D(a,b)(d,c)),
+      d(()) * ({ b.read; A(a,b)(d,c)})
+    );
+
+  /**
+  * A cell of the scheduler in another intermediate state.
+  */
+  def C(a: Chan[unit], b: Chan[unit])(d: Chan[unit], c: Chan[unit]): unit = {
+    c.read;
+    B(a,b)(d,c)
+  }
+
+  /**
+  * A cell of the scheduler whose attached agent is not yet allowed to start.
+  */
+  def D(a: Chan[unit], b: Chan[unit])(d: Chan[unit], c: Chan[unit]): unit = {
+    d.write(());
+    A(a,b)(d,c)
+  }
+
+  //***************** Agents ******************//
+
+  def agent(i: Int)(a: Chan[unit], b: Chan[unit]): unit = {
+    Thread.sleep(random.nextInt(1000) + 1);
+    a.write(());
+    System.out.println("Starting agent " + i);
+    Thread.sleep(random.nextInt(1000) + 1);
+
+    // 10% chance that we sleep for a long while.
+    if(random.nextInt(10) == 0) {
+      System.out.println("Agent " + i + " sleeps");
+      Thread.sleep(20000);
+    }
+
+    b.write(());
+    System.out.println("Ending agent " + i);
+    agent(i)(a, b)
+  }
+
+  //***************** Entry function ******************//
+
+  /**
+  * Creates a scheduler for five agents (programs).
+  */
+
+  def main(args: Array[String]): unit = {
+    val agentNb = 5;
+    val agents = for(val i <- List.range(0, agentNb)) yield agent(i);
+    scheduleAgents(agents);
+  }
+
+  //***************** Infrastructure *****************//
+
+  /**
+  * A cell is modelled as a function that takes as parameters
+  * input and output channels and which returns nothing.
+  */
+  type Cell = (Chan[unit], Chan[unit]) => unit;
+
+  /**
+  * Creates a cell composed of two cells linked together.
+  */
+  def join(cell1: Cell, cell2: Cell): Cell =
+    (l: Chan[unit], r: Chan[unit]) => {
+      val link = new Chan[unit];
+      spawn < cell1(l, link) | cell2(link, r) >
+    };
+
+  /**
+  * Links the output of a cell to its input.
+  */
+  def close(cell: Cell): unit = {
+    val a = new Chan[unit];
+    cell(a, a)
+  }
+
+  /**
+  * Creates a cell consisting of a chain of cells.
+  */
+  def chain(cells: List[Cell]): Cell =
+    cells reduceLeft join;
+
+  /**
+  * Creates a cell consisting of a chain of cells.
+  */
+  def makeRing(cells: List[Cell]): unit =
+    close(chain(cells));
+
+  /**
+  * An agent is modelled as a function that takes as parameters channels to
+  * signal that it has started or finished.
+  */
+  type Agent = (Chan[unit], Chan[unit]) => unit;
+
+  /**
+  * Takes a list of agents and schedules them.
+  */
+  def scheduleAgents(agents: List[Agent]): unit = {
+    var firstAgent = true;
+    val cells = agents map (ag => {
+      val a = new Chan[unit];
+      val b = new Chan[unit];
+      spawn < ag(a, b) >;
+      if (firstAgent) {
+	firstAgent = false;
+	A(a, b)
+      }
+      else
+	D(a, b)
+    });
+    makeRing(cells)
+  }
+}
+
+