Programming Assignment 7 - Picky Consumer Synchronization

See the assignment turn-in page (last modified on 16 July 2003) for instructions on turning in your assignment.

interface WidgetInterface {
  public int [] getAttributes();
  }

getAttributes() returns an a-element array; the ith array element is the value of attribute i.

p > 0 producers make widgets and c > 0 consumers use them; both synchronize through a store:

interface StoreInterface {
  public void deliver(WidgetInterface widget);
  public WidgetInterface purchase(int [] type);
  }

You can find these interfaces in /export/home/class/cs-598/a7 from any cslab machine or rockhopper.

The purchase() argument describes the specific attribute values the desired widget should have; the argument format is the same as the array returned by getAttributes(). A consumer can only buy one widget per purchase, and a producer can only drop off one widget per delivery, but, as is usually the case in producer-consumer problems, they can make arbitrarily many purchases and deliveries.

Use these interfaces to implement a program that allows producers and consumers to conduct business, subject to the following constraints:

• Satisfaction. Every widget received by a consumer should match exactly the attributes specified by the consumer.

• Fairness. If two consumers are waiting for the same widget, the consumer that's been waiting the longest should receive the widget, should it be delivered to the store.

• Efficiency. Consumers should be unblocked a minimum number of times; ideally just once when the widget arrives at the store.

Your program should accept the following command-line options:

• -an - each widget has n attributes.

• -vn - each attribute has n values.

• -cn - there are n consumers.

• -pn - there are n producers.

• -sn - the store has a maximum capacity of n widgets.

The default value for all options is n = 10 except for the -s option, where the default value is n = 100.

Note that it is possible for the system to deadlock; your program should detect deadlock and exit with an error message.