use List instead of Stack

db-async-common/src/main/scala/com/github/mauricio/async/db/pool/SingleThreadedAsyncObjectPool.scala

@@ -22,7 +22,7 @@ import com.github.mauricio.async.db.util.{Log, Worker}
 import java.util.concurrent.atomic.AtomicLong
 import java.util.{Timer, TimerTask}
 
-import scala.collection.mutable.{ArrayBuffer, Queue, Stack}
+import scala.collection.mutable.{ArrayBuffer, Queue}
 import scala.concurrent.{Future, Promise}
 import scala.util.{Failure, Success}
 
@@ -52,7 +52,7 @@ class SingleThreadedAsyncObjectPool[T](
  import SingleThreadedAsyncObjectPool.{Counter, log}
 
  private val mainPool = Worker()
- private var poolables = new Stack[PoolableHolder[T]]()
+ private var poolables = List.empty[PoolableHolder[T]]
  private val checkouts = new ArrayBuffer[T](configuration.maxObjects)
  private val waitQueue = new Queue[Promise[T]]()
  private val timer = new Timer("async-object-pool-timer-" + Counter.incrementAndGet(), true)
@@ -171,7 +171,7 @@ class SingleThreadedAsyncObjectPool[T](
  */
 
  private def addBack(item: T, promise: Promise[AsyncObjectPool[T]]) {
- this.poolables.push(new PoolableHolder[T](item))
+ this.poolables ::= new PoolableHolder[T](item)
 
  if (this.waitQueue.nonEmpty) {
  this.checkout(this.waitQueue.dequeue())
@@ -226,7 +226,9 @@ class SingleThreadedAsyncObjectPool[T](
  case e: Exception => promise.failure(e)
  }
  } else {
- val item = this.poolables.pop().item
+ val h :: t = this.poolables
+ this.poolables = t
+ val item = h.item
  this.checkouts += item
  promise.success(item)
  }

postgresql-async/src/main/scala/com/github/mauricio/async/db/postgresql/column/ArrayDecoder.scala

@@ -19,7 +19,7 @@ package com.github.mauricio.async.db.postgresql.column
 import com.github.mauricio.async.db.column.ColumnDecoder
 import com.github.mauricio.async.db.postgresql.util.{ArrayStreamingParserDelegate, ArrayStreamingParser}
 import scala.collection.IndexedSeq
-import scala.collection.mutable.{ArrayBuffer, Stack}
+import scala.collection.mutable.ArrayBuffer
 import com.github.mauricio.async.db.general.ColumnData
 import io.netty.buffer.{Unpooled, ByteBuf}
 import java.nio.charset.Charset
@@ -32,12 +32,13 @@ class ArrayDecoder(private val decoder: ColumnDecoder) extends ColumnDecoder {
  buffer.readBytes(bytes)
  val value = new String(bytes, charset)
 
- val stack = new Stack[ArrayBuffer[Any]]()
+ var stack = List.empty[ArrayBuffer[Any]]
  var current: ArrayBuffer[Any] = null
  var result: IndexedSeq[Any] = null
  val delegate = new ArrayStreamingParserDelegate {
  override def arrayEnded {
- result = stack.pop()
+ result = stack.head
+ stack = stack.tail
  }
 
  override def elementFound(element: String) {
@@ -63,7 +64,7 @@ class ArrayDecoder(private val decoder: ColumnDecoder) extends ColumnDecoder {
  case None => {}
  }
 
- stack.push(current)
+ stack ::= current
  }
  }