Question

I need to implement a prioritised collection.

Assuming we have the following three values in the collection (and their priorities):

thisIsUrgent = Priority.High
thisIsImportant = Priority.Medium
thisIsBoring = Priority.Low

I want to use MoveNext() to go through the collection to get another value.
Assuming I’m looping ten times, each time printing the value from MoveNext(), the desired output is:

thisIsUrgent

thisIsImportant

thisIsUrgent

thisIsUrgent

thisIsBoring

thisIsImportant

thisIsUrgent

thisIsUrgent

thisIsImportant

thisIsBoring

So basically, I get five high priority values, three normal and one low.

Any ideas?

Answer 1

the simplest approach is to have 3 collections behind one interface. When calling MoveNext check the one with highest priority, if there are messges return them until queue gets empty. Then lower and lower. Then you can improve algorithm of picking next queue, for example implement probabilistic one.

In your particular case you should use probabilistic scheduling.

• Urgent has 5/10 = 0.5
• Medium has 0.3
• Low has 0.2

At each turn gerate random number in range [0; 1]. if value falls into [0; 0,5] then pick from Urgent queue, if into [0,5; 0,8] then Medium, [0,8; 1] -> Low;