Order Center

• This is the store that customers enter and place orders from registers where a employee awaits them
• There are 5 Registers (Cashiers) (different threads)
• Only Two employees(Simon and Simon -> Simons) call to the Warehouse for to place orders
• Simons read from the queue and calls the warehouse ensuring the order is placed
• The order queue is a shared resource amongst 3 cashiers and simon
• Orders are collected in a local cached queue
• Each order is a request to Warehouse
• Response is received once the order is delivered to Warehouse (not when it's delivered)
• Each Simon can make 1 phone-call at a time
• Since each simon has a different phone line, they have different clients
• producer-consumer is implemented with a semaphore(number of simons)
• When an order is placed and each simon is talking, order waits for a simon to call the warehouse and get an approval
• This is a blocking operation

Warehouse

• Warehouse manager is Dan
• Each call from Simons is transferred to Dan
• Dan places orders to queue where delivery cars will read from
• Dan is the server
• Warehouse has multiple DeliveryCars for orders
• Each delivery car takes random amount of time to deliver a single order
• Due to traffic and chaos a delivery may take EstimatedTime + RandomWastedTime(between 0-0.5 of estimated time)
• Dan checks if the orders are made in time
• If the random estimated time is 3 seconds, Dan gets mad if it's delivered in 1.2 times Estimated 3.6seconds
• Each delivery car has its own thread
• The orders are collected into a producer-consumer queue with mutex and cv
• When delivery is made and car returns, Dan is notified (promise-future) (queue<future<order>>)
• In a detached thread Dan keeps time for orders
• If the critical time (time which makes Dan angry) is met and the car is not returned, Dan punches a wall std::cerr
• If delivery is on time Dan is happy std::cout