SE-631

Real-Time System Design and Implementation

Lab Assignment 4    (Due Wednesday, March 14)

Do the following on top of your Lab 3 work:
  

   1)  Remove the insert task and the three lookup tasks. Also remove the progStop
        function.

 

   2)  Rewrite the progStart function to spawn one requestHandler task, one  
        insertRequest task and one lookupRequest task, with the lookupRequest task
        spawned 200 clock ticks later than the other two tasks are. Also create two
        message queues: insertMsgQ and lookupMsgQ.

 

   3)  The insertRequest task periodically sends messages to insertMsgQ requesting
        to insert new items to the database.
        -- Each time it sends a request, it sleeps for 15 clock ticks.

        -- The request message includes the new item ID and item price.
        -- The values of item ID and item price are set according to the algorithm used
            for the insert task in Lab 3.

   4)  The lookupRequest task periodically sends messages to lookupMsgQ
         requesting to inquire item prices:
        -- Each time it sends a request, it sleeps for 75 clock ticks.

        -- The request message includes the inquired item ID only.
        -- The item ID is set according to the algorithm used for the lookup tasks in
            Lab 3.

 

   5)  The requestHandler task keeps checking the two message queues.

         -- Each round it checks insertMsgQ first then lookupMsgQ.
         -- If no message is received from either queue in a round of polling, it sleeps
             for 10 clock ticks.
         -- When a message from insertMsgQ is received, it inserts the corresponding
             node to the trees.
         -- When a message from lookupMsgQ is received, it searches the trees for the
             corresponding node and then display the item price.
 

   6)  The program runs for 20 seconds then it automatically stops, with all trees
        displayed and then erased.

On the due day, you need to send me a softcopy of your source code. You also
need to give me a demo of your work in the lab.