Forum ‹ C# ‹ Copying a List gives problems?!

[GBurg]

Hi all,

In my error logs I get this error (it is very rare, twice in thousands of instances):

Destination array was not long enough. Check destIndex and length, and the array's lower bounds.

at System.Array.Copy(Array sourceArray, Int32 sourceIndex, Array destinationArray, Int32 destinationIndex, Int32 length, Boolean reliable)
at System.Array.Copy(Array sourceArray, Int32 sourceIndex, Array destinationArray, Int32 destinationIndex, Int32 length)
at System.Collections.Generic.List`1.CopyTo(T[] array, Int32 arrayIndex)
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at MyGame.Player.get_bikesCopy()
at MyGame.Room.mhRoundCountdownStart(NetUser nu, Message message)
at MyGame.Room.handleMessage(NetUser nu, Message message)
at MyGame.Room.GotMessage(NetUser nu, Message message)


So it looks like I have an error in get_bikesCopy, right...? This is the code for Player.get_bikesCopy:

Code: Select all

public List<Bike> bikesCopy {
      get {
        List<Bike> bs;
        lock (_bikes) bs = new List<Bike>(_bikes);
        return bs;
      }
    }


There are no cpu aborts... What could be the problem? Seems like bug free code, right? Could it be that this code fails when the _bikes List is not initialized?

Best,

Geert

[GBurg]

Guys, anybody has an idea why this happens?

[FulaFisken]

you should not lock the list itself, you should have a listLock object that is locked in all places where the list can be changed. Something like below. You might even need to lock while iterating over your list if you want to make sure it isn't changed while doing so.

Code: Select all

private Object listLock = new Object();

public void remove()
{
    lock(listLock)
    {
        //remove from list
    }
}

public void add()
{
    lock(listLock)
    {
        //add to list
    }
}

public void copy()
{
    lock(listLock)
    {
        //copy list
    }
}


[Benjaminsen]

What FulaFisken said