Howdy,
You can save some memory by using findMap:
def joinOrders(o1: LimitOrder): Unit = {
/* select all orders where status=NEW and where that.tradeType !=
order1.tradeType */
val newOrders = LimitOrderMetaObj.findMap(By(LimitOrderMetaObj.status,
"NEW")){o2 => Full(o2).filter(o2.tradeType.name <http://o2.tradetype.name/>!=
o1.tradeType.name <http://o1.tradetype.name/>)}
findMap applies the filtering operation as each row is pulled from the
RDBMS... so you'll have fewer objects in memory.
In terms of the remaining logic... I'm a little lost in your code... can you
describe the logic? What gets updated under which conditions?
On Wed, Jul 22, 2009 at 5:35 AM, Hannes <[email protected]> wrote:
>
> Hi Lifters,
>
> It seems like I'm having problems to modify items that are already in
> the database. What I do is, first find the item, then set a new value to
> it and then save it. So far so good, or?
>
> Because its a expensive filter process to find those items to modify, I
> made a local copy of the sub-list that contains the most interesting
> items. This sub-list is processed further on and when I finally know
> which items to modify, I look those ones up in the database again and
> set the values. I hope it makes sence...
>
> thanks
>
> Here's the code:
>
> def joinOrders(o1: LimitOrder): Unit = {
> /* select all orders where status=NEW and where that.tradeType !=
> order1.tradeType */
> val newOrders =
> LimitOrderMetaObj.findAll(By(LimitOrderMetaObj.status,
> "NEW")).toList.filter(o2 => o2.tradeType.name != o1.tradeType.name)
>
> def decideByTradeType: List[LimitOrder] = {
> /* keep all orders where that.marketPoint <= order1.marketPoint
> * sort the list from lowest to highest marketPoint */
> if (o1.tradeType.name == "BUY")
> newOrders.filter(o2 => o2.marketPoint.is <=
> o1.marketPoint.is).sort((s, t) => s.marketPoint.is < t.marketPoint.is)
> /* keep all orders where that.marketPoint >= order1.marketPoint
> * sort the list from highest to lowest marketPoint */
> else //because there are only two different types! Its the same
> as: if (o1.tradeType.name == "SELL")
> newOrders.filter(o2 => o2.marketPoint.is >=
> o1.marketPoint.is).sort((s, t) => s.marketPoint.is > t.marketPoint.is)
> }
>
> var i = 0
> var done = false
> val remainingOrders = decideByTradeType
> while (i < remainingOrders.length && !done) {
> if (remainingOrders(i).lots == o1.lots) {
> LimitOrderMetaObj.find(By(LimitOrderMetaObj.id,
> remainingOrders(i).id)).map(_.status.set("OPEN")) openOr 0L
> LimitOrderMetaObj.find(By(LimitOrderMetaObj.id,
> remainingOrders(i).id)).map(_.save) openOr 0L
> LimitOrderMetaObj.find(By(LimitOrderMetaObj.id,
> o1.id)).map(_.status.set("OPEN")) openOr 0L
> LimitOrderMetaObj.find(By(LimitOrderMetaObj.id,
> o1.id)).map(_.save) openOr 0L
> done = true
> }
> if (remainingOrders(i).lots.is < o1.lots.is) {
> LimitOrderMetaObj.find(By(LimitOrderMetaObj.id,
> remainingOrders(i).id)).map(_.status.set("OPEN")) openOr 0L
> LimitOrderMetaObj.find(By(LimitOrderMetaObj.id,
> remainingOrders(i).id)).map(_.save) openOr 0L
> LimitOrderMetaObj.find(By(LimitOrderMetaObj.id,
> o1.id)).map(_.lots.set(o1.lots.is - remainingOrders(i).lots.is)) openOr 0L
> LimitOrderMetaObj.find(By(LimitOrderMetaObj.id,
> o1.id)).map(_.save) openOr 0L
> }
> if (remainingOrders(i).lots.is > o1.lots.is) {
> LimitOrderMetaObj.find(By(LimitOrderMetaObj.id,
> o1.id)).map(_.status.set("OPEN")) openOr 0L
> LimitOrderMetaObj.find(By(LimitOrderMetaObj.id,
> o1.id)).map(_.save) openOr 0L
> LimitOrderMetaObj.find(By(LimitOrderMetaObj.id,
> remainingOrders(i).id)).map(_.lots.set(remainingOrders(i).lots.is -
> o1.lots.is)) openOr 0L
> LimitOrderMetaObj.find(By(LimitOrderMetaObj.id,
> remainingOrders(i).id)).map(_.save) openOr 0L
> done = true
> }
> i = i + 1
> }
> }
>
> >
>
--
Lift, the simply functional web framework http://liftweb.net
Beginning Scala http://www.apress.com/book/view/1430219890
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