在 Java 中，可以同步访问多线程环境中所需的共享资源的方法或块。
我想知道这样做的“Scala Actors”方式是如何工作的。
假设我有一个java.sql.Connection我希望提供线程安全访问的对象连接池。我将它实现为一个接收消息并向发送者发送回连接的参与者。
似乎有三种方法可以做到这一点：
- 使用未来
- 利用
!? - 有需要
Connection也是演员的班级
代码：
sealed abstract class ConnectionPoolMessage
case class NewConnection extends ConnectionPoolMessage
case class CloseConnection(c:Connection) extends ConnectionPoolMessage
class ConnectionPool extends Actor {
def act() {
while (true) {
receive() {
case NewConnection => sender ! getConnectionFromPool
case CloseConnection(conn) => returnConnection(conn)
}
}
}
}
// Here, my "do stuff" method is all in one place, and I block waiting
// on the Future from the pool; however this could take forever and cause trouble
class UsingFuture {
val pool = new ConnectionPool
def doSomething() {
val connectionFuture = pool !! NewConnection
val connection = connectionFuture() // concerned that we can't timeout here
// do stuff with my Connection instance
pool ! CloseConnection(connection)
}
}
// here, I wait and just use a timeout
// Seems clean to me, I guess.
class UsingBangQuestion {
val pool = new ConnectionPool
def doSomething() {
pool !?(TIMEOUT,NewConnection) match {
case Some(conn) => {
// do something with connection
pool ! CloseConnection(conn)
}
case None => throw new RuntimeException("timed out")
}
}
}
// here, I don't worry about timeouts, cause I only use the
// the connection when I receive a message back with it.
// The problem is that I now have to split my logic up
// with two methods
class AsAnActor extends Actor {
val pool = new ConnectionPool
def startSomething() {
start
pool ! NewConnection
}
def act() {
receive() {
case conn:Connection => finishSomething(conn)
}
}
def finishSomething(conn:Connection) {
// do stuff with my Connection
pool ! CloseConnection(conn)
}
}
未来版本似乎最干净，除了我可以永远阻止的事实。
有什么想法，或者我对此的整个概念是错误的吗？