ujes/definedEngines/spark/engine/src/main/scala/com/webank/wedatasphere/linkis/engine/spark/common/LogContainer.scala

/*
 * Copyright 2019 WeBank
 *
 * 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 com.webank.wedatasphere.linkis.engine.spark.common

import scala.collection.Iterable
import scala.collection.JavaConversions._
import scala.collection.mutable.ArrayBuffer

/**
  * Created by allenlliu on 2018/11/19.
  */
class LogContainer(val logSize: Int) {

  private final val logs = new Array[String](logSize)
  private var flag, tail = 0

  def putLog(log: String): Unit = {
    logs.synchronized {
      val index = (tail + 1) % logSize
      if(index == flag) {
        flag = (flag + 1) % logSize
      }
      logs(tail) = log
      tail = index
    }
  }

  def putLogs(logs: Iterable[String]) = synchronized {
    logs.foreach(putLog)
  }

  def reset() = synchronized {
    flag = 0
    tail = 0
  }

  def getLogs: List[String] = {
    logs.synchronized {
      if(flag == tail) {
        return List.empty[String]
      }
      val _logs = ArrayBuffer[String]()
      val _tail = if(flag > tail) tail + logSize else tail
      for (index <- flag until _tail) {
        val _index = index % logSize
        _logs += logs(_index)
      }
      flag = tail
      _logs.toList
    }
  }

  def size = {
    if(flag == tail) 0
    else if(flag > tail) tail + logSize - flag
    else tail - flag
  }

  def getLogList: java.util.List[String] = getLogs

}