diff options
Diffstat (limited to 'sources/examples')
-rw-r--r-- | sources/examples/pilib/elasticBuffer.scala | 75 | ||||
-rw-r--r-- | sources/examples/pilib/handover.scala | 188 | ||||
-rw-r--r-- | sources/examples/pilib/mobilePhoneProtocol.scala | 170 | ||||
-rw-r--r-- | sources/examples/pilib/rwlock.scala | 328 | ||||
-rw-r--r-- | sources/examples/pilib/scheduler.scala | 147 | ||||
-rw-r--r-- | sources/examples/pilib/semaphore.scala | 70 | ||||
-rw-r--r-- | sources/examples/pilib/twoPlaceBuffer.scala | 74 |
7 files changed, 1052 insertions, 0 deletions
diff --git a/sources/examples/pilib/elasticBuffer.scala b/sources/examples/pilib/elasticBuffer.scala new file mode 100644 index 0000000000..50e61c291a --- /dev/null +++ b/sources/examples/pilib/elasticBuffer.scala @@ -0,0 +1,75 @@ +object elasticBuffer { + + import scala.concurrent.pilib._; + + /** + * Recursive type for channels that carry a "String" channel and + * an object of the type we define. + */ + class MetaChan extends Chan[Pair[Chan[String], MetaChan]]; + + def Buffer(put: Chan[String], get: Chan[String]): unit = { + + /** + * An empty buffer cell, ready to pass on (o,r) to the left. + */ + def Bl(i:Chan[String], l: MetaChan, + o: Chan[String], r: MetaChan): unit = + choice ( + l(Pair(o,r)) * (System.out.println("Removed one cell.")), + i * (inp => Cl(i, l, o, r, inp)) + ); + + /** + * A buffer cell containing a value, ready to receive (o,r) from the right. + */ + def Cl(i: Chan[String], l: MetaChan, + o: Chan[String], r: MetaChan, content: String): unit = + choice ( + o(content) * (Bl(i,l,o,r)), + i * (inp => Dl(i,l,o,r,content, inp)), + r * ( { case Pair(newo, newr) => Cl(i,l,newo,newr,content) }) + ); + + /** + * Two joined buffer cells, of type Cl. + */ + def Dl(i: Chan[String], l: MetaChan, + o: Chan[String], r: MetaChan, + content: String, inp: String): unit = { + val newlr = new MetaChan; + val newio = new Chan[String]; + spawn < Cl(i, l, newio, newlr, inp) | Cl(newio, newlr, o, r,content) >; + } + + // l and r channels for the leftmost and rightmost cell, respectively. + val unused1 = new MetaChan; + val unused2 = new MetaChan; + + Bl(put, unused1, get, unused2); + } + + 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) | Buffer(put, get) > + } + +} diff --git a/sources/examples/pilib/handover.scala b/sources/examples/pilib/handover.scala new file mode 100644 index 0000000000..906af55689 --- /dev/null +++ b/sources/examples/pilib/handover.scala @@ -0,0 +1,188 @@ +/** +* Handover example with recursive types for channels. +*/ +object handoverRecursive { + + import concurrent.pilib._; + + val random = new java.util.Random(); + + /** + * Recursive type for channels that carry a channel "unit" and + * an object of the type we define. + */ + class Switch extends Chan[Pair[Chan[unit], Switch]]; + + /** + * Car. + */ + def Car(talk: Chan[unit], switch: Switch): unit = + choice ( + switch * ({ case Pair(t,s) => Car(t, s) }), + talk(()) * ( { + Thread.sleep(1 + random.nextInt(1000)); + System.out.println("Car emitted a message."); + Car(talk, switch) + }) + ); + + /** + * Control center. + */ + def Control(talk1: Chan[unit], switch1: Switch, + gain1: Switch, lose1: Switch, + talk2: Chan[unit], switch2: Switch, + gain2: Switch, lose2: Switch): unit + = { + def Control1: unit= { + Thread.sleep(1 + random.nextInt(1000)); + lose1.write(Pair(talk2, switch2)); + gain2.write(Pair(talk2, switch2)); + Control2; + } + def Control2: unit = { + Thread.sleep(1 + random.nextInt(1000)); + lose2.write(Pair(talk1, switch1)); + gain1.write(Pair(talk1, switch1)); + Control1; + } + Control1; + } + + /** + * Active transmitter. + */ + def ActiveTransmitter(id: String, talk: Chan[unit], switch: Switch, + gain: Switch, lose: Switch): unit + = + choice ( + talk * (x => { + System.out.println(id + " received a message."); + ActiveTransmitter(id, talk, switch, gain, lose) + }), + lose * ({ case Pair(t, s) => { + switch.write(Pair(t, s)); + IdleTransmitter(id, gain, lose) + }}) + ); + + /** + * Idle transmitter. + */ + def IdleTransmitter(id: String, gain: Switch, lose: Switch): unit = { + val Pair(t, s) = gain.read; + ActiveTransmitter(id, t, s, gain, lose) + } + + def main(args: Array[String]): unit = { + val talk1 = new Chan[unit]; + val switch1 = new Switch; + val gain1 = new Switch; + val lose1 = new Switch; + val talk2 = new Chan[unit]; + val switch2 = new Switch; + val gain2 = new Switch; + val lose2 = new Switch; + spawn < + Car(talk1, switch1) | + ActiveTransmitter("Transmitter 1", talk1, switch1, gain1, lose1) | + IdleTransmitter("Transmitter 2", gain2, lose2) | + Control(talk1, switch1, gain1, lose1, talk2, switch2, gain2, lose2) + > + } +} + +/** +* Handover example with type casts. +*/ +object handoverCast { + + import concurrent.pilib._; + + val random = new java.util.Random(); + + /** + * Car. + */ + def Car(talk: Chan[Any], switch: Chan[Any]): unit = + choice ( + switch * (o => { + val Pair(t,s) = o.asInstanceOf[Pair[Chan[Any],Chan[Any]]]; + Car(t, s) + }), + talk(()) * ( { + Thread.sleep(1 + random.nextInt(1000)); + System.out.println("Car emitted a message."); + Car(talk, switch) + }) + ); + + /** + * Control center. + */ + def Control(talk1: Chan[Any], switch1: Chan[Any], + gain1: Chan[Any], lose1: Chan[Any], + talk2: Chan[Any], switch2: Chan[Any], + gain2: Chan[Any], lose2: Chan[Any]): unit + = { + def Control1: unit= { + Thread.sleep(1 + random.nextInt(1000)); + lose1.write(Pair(talk2, switch2)); + gain2.write(Pair(talk2, switch2)); + Control2 + } + def Control2: unit = { + Thread.sleep(1 + random.nextInt(1000)); + lose2.write(Pair(talk1, switch1)); + gain1.write(Pair(talk1, switch1)); + Control1 + } + Control1 + } + + /** + * Active transmitter. + */ + def ActiveTransmitter(id: String, talk: Chan[Any], switch: Chan[Any], + gain: Chan[Any], lose: Chan[Any]): unit + = + choice ( + talk * (x => { + System.out.println(id + " received a message."); + ActiveTransmitter(id, talk, switch, gain, lose) + }), + lose * (o => { + val Pair(t, s) = o.asInstanceOf[Pair[Chan[Any],Chan[Any]]]; + switch.write(Pair(t, s)); + IdleTransmitter(id, gain, lose) + }) + ); + + /** + * Idle transmitter. + */ + def IdleTransmitter(id: String, gain: Chan[Any], lose: Chan[Any]): unit = { + val Pair(t, s) = gain.read.asInstanceOf[Pair[Chan[Any],Chan[Any]]]; + ActiveTransmitter(id, t, s, gain, lose) + } + + def main(args: Array[String]): unit = { + val talk1 = new Chan[Any]; + val switch1 = new Chan[Any]; + val gain1 = new Chan[Any]; + val lose1 = new Chan[Any]; + val talk2 = new Chan[Any]; + val switch2 = new Chan[Any]; + val gain2 = new Chan[Any]; + val lose2 = new Chan[Any]; + spawn < + Car(talk1, switch1) | + ActiveTransmitter("Transmitter 1", talk1, switch1, gain1, lose1) | + IdleTransmitter("Transmitter 2", gain2, lose2) | + Control(talk1, switch1, gain1, lose1, talk2, switch2, gain2, lose2) + > + } + +} + + diff --git a/sources/examples/pilib/mobilePhoneProtocol.scala b/sources/examples/pilib/mobilePhoneProtocol.scala new file mode 100644 index 0000000000..553bc68e7f --- /dev/null +++ b/sources/examples/pilib/mobilePhoneProtocol.scala @@ -0,0 +1,170 @@ +/** +* Mobile phone protocol. +* Equivalent to a three-place buffer. +* @see Bjoern Victor "A verification tool for the polyadic pi-calculus". +*/ +object mobilePhoneProtocol { + + import concurrent.pilib._; + + val random = new java.util.Random(); + + // Internal messages exchanged by the protocol. + trait Message; + + // Predefined messages used by the protocol. + case class Data() extends Message; + case class HoCmd() extends Message; // handover command + case class HoAcc() extends Message; // handover access + case class HoCom() extends Message; // handover complete + case class HoFail() extends Message; // handover fail + case class ChRel() extends Message; // release + case class Voice(s: String) extends Message; // voice + case class Channel(n: Chan[Message]) extends Message; // channel + + def MobileSystem(in: Chan[String], out: Chan[String]): unit = { + + def CC(fa: Chan[Message], fp: Chan[Message], l: Chan[Channel]): unit = + choice ( + in * (v => { fa.write(Data()); fa.write(Voice(v)); CC(fa, fp, l) }) + , + l * (m_new => { + fa.write(HoCmd()); + fa.write(m_new); + choice ( + fp * ({ case HoCom() => { + System.out.println("Mobile has moved from one cell to another"); + fa.write(ChRel()); + val Channel(m_old) = fa.read; + l.write(Channel(m_old)); + CC(fp, fa, l) + }}) + , + fa * ({ case HoFail() => { + System.out.println("Mobile has failed to move from one cell to another"); + l.write(m_new); + CC(fa, fp, l) + }}) + ) + }) + ); + + /* + * Continuously orders the MSC to switch the MS to the non-used BS. + */ + def HC(l: Chan[Channel], m: Chan[Message]): unit = { + Thread.sleep(1 + random.nextInt(1000)); + l.write(Channel(m)); + val Channel(m_new) = l.read; + HC(l, m_new) + } + + /** + * Mobile switching center. + */ + def MSC(fa: Chan[Message], fp: Chan[Message], m: Chan[Message]): unit = { + val l = new Chan[Channel]; + spawn < HC(l, m) | CC(fa, fp, l) > + } + + /** + * Active base station. + */ + def BSa(f: Chan[Message], m: Chan[Message]): unit = + (f.read) match { + case Data() => { + val v = f.read; + m.write(Data()); + m.write(v); + BSa(f, m) + } + case HoCmd() => { + val v = f.read; + m.write(HoCmd()); + m.write(v); + choice ( + f * ({ case ChRel() => { + f.write(Channel(m)); + BSp(f, m) + }}) + , + m * ({ case HoFail() => { + f.write(HoFail()); + BSa(f, m) + }}) + ) + } + }; + + /** + * Passive base station. + */ + def BSp(f: Chan[Message], m: Chan[Message]): unit = { + val HoAcc = m.read; + f.write(HoCom()); + BSa(f, m) + }; + + /** + * Mobile station. + */ + def MS(m: Chan[Message]): unit = + (m.read) match { + case Data() => { + val Voice(v) = m.read; + out.write(v); + MS(m) + } + case HoCmd() => + (m.read) match { + case Channel(m_new) => { + if (random.nextInt(1) == 0) + choice ( m_new(HoAcc()) * (MS(m_new)) ); + else + choice ( m(HoFail()) * (MS(m)) ); + } + } + }; + + def P(fa: Chan[Message], fp: Chan[Message]): unit = { + val m = new Chan[Message]; + spawn < MSC(fa, fp, m) | BSp(fp, m) > + } + + def Q(fa: Chan[Message]): unit = { + val m = new Chan[Message]; + spawn < BSa(fa, m) | MS(m) > + } + + val fa = new Chan[Message]; + val fp = new Chan[Message]; + spawn < Q(fa) | P(fa, fp) >; + } + + //***************** Entry function ******************// + + def main(args: Array[String]): unit = { + + 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) + } + + val put = new Chan[String]; + val get = new Chan[String]; + spawn < Producer(0, put) | Consumer(get) | MobileSystem(put, get) > + } + +} + + diff --git a/sources/examples/pilib/rwlock.scala b/sources/examples/pilib/rwlock.scala new file mode 100644 index 0000000000..65578ea51b --- /dev/null +++ b/sources/examples/pilib/rwlock.scala @@ -0,0 +1,328 @@ +/** +* From Pi to Scala: Semaphores, monitors, read/write locks. +* Readers/writers locks. +*/ +object rwlock { + + import scala.concurrent.pilib._; + + class Signal extends Chan[unit] { + def send = write(()); + def receive = read; + } + + class CountLock { + private val busy = new Signal; + def get = busy.send; + def release = busy.receive; + spawn < release > + } + + /** A binary semaphore + */ + class Lock { + private val busy = new Signal; + private val free = new Signal; + def get = busy.send; + def release = free.send; + spawn < (while (true) { + choice ( + busy * (x => free.receive), + free * (x => ()) + ) + }) + > + } + + /** A monitor a la Java + */ + class JavaMonitor { + + private val lock = new Lock; + + private var waiting: List[Signal] = Nil; + + def synchronized[a](def s: a): a = { + lock.get; val result = s; lock.release; result + } + + def Wait = { + val s = new Signal; + waiting = s :: waiting; + lock.release; + s.receive; + lock.get; + } + + def Notify = { + if (!waiting.isEmpty) { + waiting.head.send; + waiting = waiting.tail; + } + } + + def NotifyAll = { + while (!waiting.isEmpty) { + waiting.head.send; + waiting = waiting.tail; + } + } + + def await(def cond: boolean): unit = while (false == cond) (Wait) + } + + /* + class Buffer[a](size: Int) extends JavaMonitor with { + var in = 0, out = 0, n = 0; + val elems = new Array[a](size); + def put(x: a) = synchronized { + await(n < size); + elems(out) = x; + out = (out + 1) % size; + } + def get: a = synchronized { + await(n > 0); + val x = elems(in); + in = (in + 1) % size; + x + } + } + */ + + /** A readers/writers lock. */ + trait ReadWriteLock { + def startRead: unit; + def startWrite: unit; + def endRead: unit; + def endWrite: unit; + } + + /** + * A readers/writers lock, using monitor abstractions. + */ + class ReadWriteLock1 extends JavaMonitor with ReadWriteLock { + + private var nactive: int = 0; + private var nwriters: int = 0; + + def status = + System.out.println(nactive + " active, " + nwriters + " writers"); + + def startRead = synchronized { + await(nwriters == 0); + nactive = nactive + 1; + status + } + + def startWrite = synchronized { + nwriters = nwriters + 1; + await(nactive == 0); + nactive = 1; + status + } + + def endRead = synchronized { + nactive = nactive - 1; + if (nactive == 0) NotifyAll; + status + } + + def endWrite = synchronized { + nwriters = nwriters - 1; + nactive = 0; + NotifyAll; + status + } + } + + /** A readers/writers lock, using semaphores + */ + class ReadWriteLock2 extends ReadWriteLock { + + private var rc: int = 0; // reading readers + private var wc: int = 0; // writing writers + private var rwc: int = 0; // waiting readers + private var wwc: int = 0; // waiting writers + private val mutex = new Lock; + private val rsem = new Lock; + private val wsem = new Lock; + + def startRead = { + mutex.get; + if (wwc > 0 || wc > 0) { + rwc = rwc + 1; + mutex.release; + rsem.get; + rwc = rwc - 1; + } + rc = rc + 1; + if (rwc > 0) rsem.release; + mutex.release + } + + def startWrite = { + mutex.get; + if (rc > 0 || wc > 0) { + wwc = wwc + 1; + mutex.release; + wsem.get; + wwc = wwc - 1; + } + wc = wc + 1; + mutex.release; + } + + def endRead = { + mutex.get; + rc = rc - 1; + if (rc == 0 && wwc > 0) wsem.release; + mutex.release + } + + def endWrite = { + mutex.get; + wc = wc - 1; + if (rwc > 0) + rsem.release + else if (wwc > 0) wsem.release; + mutex.release + } + } + + /** A readers/writers lock, using channels, without priortities + */ + class ReadWriteLock3 extends ReadWriteLock { + + private val sr = new Signal; + private val er = new Signal; + private val sw = new Signal; + private val ew = new Signal; + + def startRead = sr.send; + def startWrite = sw.send; + def endRead = er.send; + def endWrite = ew.send; + + private def rwlock: unit = choice ( + sr * (x => reading(1)), + sw * (x => { ew.receive; rwlock }) + ); + + private def reading(n: int): unit = choice ( + sr * (x => reading(n+1)), + er * (x => if (n == 1) rwlock else reading(n-1)) + ); + + spawn < rwlock >; + } + + /** Same, with sequencing + */ + class ReadWriteLock4 extends ReadWriteLock { + + private val rwlock = new ReadWriteLock3; + + private val sr = new Signal; + private val ww = new Signal; + private val sw = new Signal; + + def startRead = sr.send; + def startWrite = { ww.send; sw.send; } + def endRead = rwlock.endRead; + def endWrite = rwlock.endWrite; + + private def queue: unit = choice ( + sr * (x => { rwlock.startRead ; queue }), + ww * (x => { rwlock.startWrite; sw.receive; queue }) + ); + + spawn < queue >; + } + + /** Readwritelock where writers always have priority over readers + */ + class ReadWriteLock5 extends ReadWriteLock { + + private val sr = new Signal; + private val er = new Signal; + private val ww = new Signal; + private val sw = new Signal; + private val ew = new Signal; + + def startRead = sr.send; + def startWrite = { ww.send; sw.send; } + def endRead = er.send; + def endWrite = ew.send; + + private def Reading(nr: int, nw: int): unit = + if (nr == 0 && nw == 0) + choice ( + sr * (x => Reading(1, 0)), + ww * (x => Reading(0, 1)) + ) + else if (nr == 0 && nw != 0) { + sw.receive; + Writing(nw); + } + else if (nr != 0 && nw == 0) + choice ( + sr * (x => Reading(nr + 1, 0)), + er * (x => Reading(nr - 1, 0)), + ww * (x => Reading(nr, 1)) + ) + else if (nr != 0 && nw != 0) + choice ( + ww * (x => Reading(nr, nw + 1)), + er * (x => Reading(nr - 1, nw)) + ); + + private def Writing(nw: int): unit = choice ( + ew * (x => Reading(0, nw - 1)), + ww * (x => Writing(nw + 1)) + ); + + spawn < Reading(0, 0) >; + + } + + /** + * Main function. + */ + def main(args: Array[String]): unit = { + val random = new java.util.Random(); + + def reader(i: int, rwlock: ReadWriteLock): unit = { + Thread.sleep(1 + random.nextInt(100)); + System.err.println("Reader " + i + " wants to read."); + rwlock.startRead; + System.err.println("Reader " + i + " is reading."); + Thread.sleep(1 + random.nextInt(100)); + rwlock.endRead; + System.err.println("Reader " + i + " has read."); + reader(i, rwlock) + } + + def writer(i: int, rwlock: ReadWriteLock): unit = { + Thread.sleep(1 + random.nextInt(100)); + System.err.println("Writer " + i + " wants to write."); + rwlock.startWrite; + System.err.println("Writer " + i + " is writing."); + Thread.sleep(1 + random.nextInt(100)); + rwlock.endWrite; + System.err.println("Writer " + i + " has written."); + writer(i, rwlock) + } + + val rwlock = args(0) match { + case "1" => new ReadWriteLock1 + case "2" => new ReadWriteLock2 + case "3" => new ReadWriteLock3 + case "4" => new ReadWriteLock4 + case "5" => new ReadWriteLock5 + } + List.range(0, 5) foreach (i => spawn < reader(i, rwlock) >); + List.range(0, 5) foreach (i => spawn < writer(i, rwlock) >); + } + +} + 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) + } +} + + 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") + } ) + } >; + } +} + diff --git a/sources/examples/pilib/twoPlaceBuffer.scala b/sources/examples/pilib/twoPlaceBuffer.scala new file mode 100644 index 0000000000..15f29dee07 --- /dev/null +++ b/sources/examples/pilib/twoPlaceBuffer.scala @@ -0,0 +1,74 @@ +/** 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) > + } + +} |