c# barcode generator library open source v is Option[Int], so we get its value or default to 0 if v is None. in Font

Creation ECC200 in Font v is Option[Int], so we get its value or default to 0 if v is None.

case class BeginXAction(id: Int) case object CommitXAction case object RollbackXAction class Acct extends Actor { private var info: Map[String, Int] = Map() private var service = (normal, false) private def normal: PartialFunction[Any, Unit] = { case GetInfo => reply(Info(info)) case SetInfo(n, v) => info += n -> v case Update(n, f) => info += n -> f(info.get(n)) case BeginXAction(id) => begin(id) } private def begin(xActionId: Int) { val oldInfo = info // capture val oldService = service val tmp: PartialFunction[Any, Unit] = { case TIMEOUT => // Rollback info = oldInfo service = oldService case (n, RollbackXAction) if n == xActionId => info = oldInfo service = oldService case (n, CommitXAction) if n == xActionId => // Commit service = oldService case (n, v) if n == xActionId && normal.isDefinedAt(v) => normal(v) } service = (tmp, true) } def act = loop { service match { case (pf, false) => react(pf) case (pf, true) => reactWithin(500)(pf) } }

this.start } object TestAcct { def doTest() = { val dpp = new Acct dpp ! Update("Savings", v => (v getOrElse 0) + 1000) dpp ! Update("Checking", v => (v getOrElse 0) + 100) val archer = new Acct archer ! Update("Savings", v => (v getOrElse 0) + 2000) archer ! Update("Checking", v => (v getOrElse 0) + 50) println("Initial balances:") println("dpp: "+(dpp ! GetInfo)) println("archer: "+(archer ! GetInfo)) var xid = 1 def transfer(who: Actor, from: String, to: String, amount: Int): Boolean = { xid += 1 who ! BeginXAction(xid) who ! (500, (xid, GetInfo)) match { case Some(Info(bal)) => if (bal.getOrElse(from, 0) > amount) { who ! (xid, Update(from, v => (v getOrElse 0) - amount)) who ! (xid, Update(to, v => (v getOrElse 0) + amount)) who ! (xid, CommitXAction) true } else { who ! (xid, RollbackXAction) false } case _ => who ! (xid, RollbackXAction) false } } transfer(dpp, println("xfer transfer(dpp, println("xfer "Savings", "Checking", 700) 1 dpp: "+(dpp ! GetInfo)) "Savings", "Checking", 700) 2 dpp: "+(dpp ! GetInfo))

def transfer2(src: Actor, sact: String, dest: Actor, dact: String, amount: Int): Boolean = { xid += 1 src ! BeginXAction(xid) dest ! BeginXAction(xid) (src ! (500, (xid, GetInfo)), dest ! (500, (xid, GetInfo))) match { case (Some(Info(sbal)), Some(Info(dbal))) => dest ! (xid, Update(dact, v => (v getOrElse 0) + amount)) if (sbal.getOrElse(sact, 0) > amount) { src ! (xid, Update(sact, v => (v getOrElse 0) - amount)) src ! (xid, CommitXAction) dest ! (xid, CommitXAction) true } else { src ! (xid, RollbackXAction) dest ! (xid, RollbackXAction) false } case _ => src ! (xid, RollbackXAction) dest ! (xid, RollbackXAction) false } } transfer2(dpp, "Checking", archer, "Checking", 700) println("XFer 700 dpp -> archer:") println("dpp: "+(dpp ! GetInfo)) println("archer: "+(archer ! GetInfo)) transfer2(dpp, "Checking", archer, "Checking", 700) println("Again, XFer 700 dpp -> archer:") println("dpp: "+(dpp ! GetInfo)) println("archer: "+(archer ! GetInfo)) transfer2(dpp, "Checking", archer, "Checking", 10) println("XFer 10 dpp -> archer:") println("dpp: "+(dpp ! GetInfo)) println("archer: "+(archer ! GetInfo)) } }

Let s step through the code. First some imports:

The TIMEOUT message will be useful for staying in the transaction boundary for a certain period of time. Next, let s define some messages:

case case case case case case case object GetInfo class Info(i: Map[String, Int]) class SetInfo(n: String, v: Int) class Update(n: String, f: Option[Int] => Int) class BeginXAction(id: Int) object CommitXAction object RollbackXAction

The XAction messages allow us to define the transactional boundaries. Next, let s define an Acct, account, Actor:

class Acct extends Actor { private var info: Map[String, Int] = Map() private var service = (normal, false)

The service variable defines how we re going to service incoming requests. By default, requests will be handled with the normal handler, but if we re in a transaction, the handler can be changed. Next, let s define the normal handler:

private def normal: PartialFunction[Any, Unit] = { case GetInfo => reply(Info(info)) case SetInfo(n, v) => info += n -> v case Update(n, f) => info += n -> f(info.get(n)) case BeginXAction(id) => begin(id) }