Ober_Cab_Services

Synchronization Problem

• This project is done as part of the Operating System course which i took in my university.
• The problem is about designing a Uber like car service.
• The component of this problem will be Riders , Cabs , Payment Servers.
• The Riders will ask the Cabs to pick them up and drop them at their destination.
• The Cabs on getting this signal will fulfil the request of the rider.
• The Rider can request for a pool-cab or a premier ride.
• If the rider does not get the Cab within the limit of the wait-time, than it has to leave the system (without riding).
• In case of the premier the cab which services the rider has to be free.
• Once the ride is finished the rider gets off the cab and proceeds to pay the fees.
• This is done by using one of the free payment servers.

My Implementation

• I have used two condition variable and two mutexes.
• Condition variable cab_free is used by riders who have not got their ride to wait on.
• cab_free is signalled by the rider which finishes it ride.
• Condition variable payment_server_free is used by riders who have not paid the fees to wait on.
• payment_server_free is signalled by the riders who have paid their fees.
• Mutexes are used to make the data manipulation atomic.
• The program starts by creating threads for each Cab, Rider, Payment servers.
• The Rider initiates the process by finding a car which is available and mathces it requirements.
• The order of riders in the system is random and this is achieved by making the thread sleep for some random amount of time before calling the method.
• The rider generate it ride-time , wait-time , cab-type for service randomly.
• If all the cabs are busy than the riders have to wait for till one of them becomes available.
• Once the riders starts it journey it marks that cab as un-available.
• The rider than will ride for the ride-time it generated randomly.
• When the ride is over the rider prints the appropriate message and also set the cab free, so the other rider can use it.
• It does so by signal on the condition variable.
• Now the riders wait for some payment server to become free.
• When they find a free payment server they engage in the process of paying the fees.
• The time to pay the fees is randomly allocated.
• When the server becomes free it is signalled by the rider.
• After this the rider successfully goes out of the system.