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Lift Framework example source code file (LAFuture.scala)

This example Lift Framework source code file (LAFuture.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lift Framework tags/keywords

abortedfutureexception, boolean, empty, empty, full, full, future, lafuture, lafuture, nil, object, t, t, unit

The Lift Framework LAFuture.scala source code

/*
 * Copyright 2009-2011 WorldWide Conferencing, LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.liftweb 
package actor 

import common._

/**
 * A container that contains a calculated value
 * or may contain one in the future
 */
class LAFuture[T] /*extends Future[T]*/ {
  private var item: T = _
  private var satisfied = false
  private var aborted = false
  private var toDo: List[T => Unit] = Nil

  /**
   * Satify the future... perform the calculation
   * the results in setting a value for the future
   */
  def satisfy(value: T): Unit = {
    val funcs = synchronized {
      try {
        if (!satisfied && !aborted) {
          item = value
          satisfied = true
          toDo
        } else Nil
      } finally {
        notifyAll()
      }
    }
    funcs.foreach(f => LAScheduler.execute(() => f(value)))
  }

  /**
   * Get the future value
   */
  def get: T = synchronized {
    if (satisfied) item
    else {
      this.wait()
      if (satisfied) item
      else if (aborted) throw new AbortedFutureException()
      else get
    }
  }

  /**
   * Execute the function with the value. If the
   * value has not been satisfied, execute the function
   * when the value is satified
   */
  def foreach(f: T => Unit) {
    val todo = synchronized {
      if (satisfied) {
        val v = item
        () => f(v)
      } else {
        toDo ::= f
        () => ()
      }
    }

    todo()
  }

  /**
   * Get the future value or if the value is not
   * satisfied after the timeout period, return an
   * Empty
   */
  def get(timeout: Long): Box[T] = synchronized {
    if (satisfied) Full(item)
    else if (aborted) Empty
    else {
      try {
        wait(timeout)
        if (satisfied) Full(item)
        else Empty
      } catch {
        case _: InterruptedException => Empty
      }
    }
  }

  /**
   * Has the future been satisfied
   */
  def isSatisfied: Boolean = synchronized {satisfied}

  /**
   * Has the future been aborted
   */
  def isAborted: Boolean = synchronized {aborted}

  /**
   * Abort the future.  It can never be satified
   */
  def abort() {
    synchronized {
      if (!satisfied && !aborted) {
        aborted = true
        notifyAll()
      }
    }
  }
}

/**
 * Thrown if an LAFuture is aborted during a get
 */
final class AbortedFutureException() extends Exception("Aborted Future")

object LAFuture {
  /**
   * Collect all the future values into the aggregate future
   * The returned future will be satisfied when all the
   * collected futures are satisfied
   */
  def collect[T](future: LAFuture[T]*): LAFuture[List[T]] = {
    val sync = new Object
    val len = future.length
    val vals = new collection.mutable.ArrayBuffer[T](len)
    var gotCnt = 0
    val ret = new LAFuture[List[T]]

    future.toList.zipWithIndex.foreach {
      case (f, idx) => 
        f.foreach {
          v => sync.synchronized {
            vals.insert(idx, v)
            gotCnt += 1
            if (gotCnt >= len) {
              ret.satisfy(vals.toList)
            }
          }
        }
    }

    ret
  }

  /**
   * Collect all the future values into the aggregate future
   * The returned future will be satisfied when all the
   * collected futures are satisfied or if any of the
   * futures is Empty, then immediately satisfy the
   * returned future with an Empty
   */
  def collectAll[T](future: LAFuture[Box[T]]*): LAFuture[Box[List[T]]] = {
    val sync = new Object
    val len = future.length
    val vals = new collection.mutable.ArrayBuffer[T](len)
    var gotCnt = 0
    val ret = new LAFuture[Box[List[T]]]

    future.toList.zipWithIndex.foreach {
      case (f, idx) => 
        f.foreach {
          vb => sync.synchronized {
            vb match {
              case Full(v) => {
                vals.insert(idx, v)
                gotCnt += 1
                if (gotCnt >= len) {
                  ret.satisfy(Full(vals.toList))
                }
              }
              
              case eb: EmptyBox => {
                ret.satisfy(eb)
              }
            }
          }
        }
    }

    ret
  }
}

Other Lift Framework examples (source code examples)

Here is a short list of links related to this Lift Framework LAFuture.scala source code file:



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