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/** Two-place buffer specification and implementation. */
object twoPlaceBuffer {
import scala.concurrent.pilib._;
/**
* Specification.
*/
def Spec[a](put: Chan[a], get: Chan[a]): unit = {
def B0: unit = {
val x = put.read;
B1(x)
}
def B1(x: a): unit = choice (
get(x) * (B0),
put * (y => B2(x, y))
);
def B2(x: a, y: a): unit = {
get.write(x);
B1(y)
};
B0
}
/**
* Implementation.
*/
def Impl[a](put: Chan[a], get: Chan[a]): unit = {
// An empty one-place buffer.
def B0(in: Chan[a], out: Chan[a]): unit = {
val x = in.read;
B1(in, out, x)
}
// A full one-place buffer containing x.
def B1(in: Chan[a], out: Chan[a], x: a): unit = {
out.write(x);
B0(in, out)
};
val hidden = new Chan[a];
spawn < B0(put, hidden) | B0(hidden, get) >
}
val random = new java.util.Random();
def Producer(n: Int, put: Chan[String]): unit = {
Thread.sleep(1 + random.nextInt(1000));
val msg = "object " + n;
put.write(msg);
System.out.println("Producer gave " + msg);
Producer(n + 1, put)
}
def Consumer(get: Chan[String]): unit = {
Thread.sleep(1 + random.nextInt(1000));
val msg = get.read;
System.out.println("Consummer took " + msg);
Consumer(get)
}
def main(args: Array[String]): unit = {
val put = new Chan[String];
val get = new Chan[String];
spawn < Producer(0, put) | Consumer(get) | Spec(put, get) >
//spawn < Producer(0, put) | Consumer(get) | Impl(put, get) >
}
}
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