Programming Project 07 Solution

Problem Description

In this project, you have to manage a list of computer servers, where each server hosts multiple users. The server data is stored as an associative data structure type called ServerData which is an STL map<string, set<string>>. Thus, the keys of this map are strings that represent server names, and the values associated with each server name is an STL set of strings that are the names of users on that server.

You will have to write functions that add a user to a server, disconnect a user from a server, balance the server load, etc.

Program Specifications

You are provided with a proj07_functions.h that contains the signatures of all the
functions you must implement. You must implement those functions and turn in your results as
proj07/proj07_functions.cpp to Mimir.    You are also provided with

proj07_main.cpp that does some minimal testing of these functions. Of course, the real test

cases are on Mimir as always.

Functions

bool AddConnection(ServerData &sd, ServerName sn, UserName un) This function tries to connect the user un to the server sn. If the server exists, it adds un to that server. If the server does not exist, it is created (added to sd) and the user un is added to that server. Both of those conditions return true

If the user un is already connected to the server sn, then no action is taken, and the function returns false.

bool DeleteConnection(ServerData &sd, ServerName sn, UserName un)

This function tries to disconnect the user un from the server sn, and returns true if d is successfully updated with that information. If the user un is not connected to the server sn, then no action is taken, and the function returns false.

ServerData ParseServerData(const std::string &fname)

fname is the name of a file that contains an arbitrary number of lines of text where each line consists of three strings, each space separated. Each line is either of two forms:
    • user_name join server_name

    • user_name leave server_name
For each line in this file, if the 2nd string is join, then add user_name to server_name. If the 2nd string is leave, remove user name from server name. If specified action cannot be performed, e.g. if trying to add user_name to server_name when user_name is already connected to server_name, then that action is simply ignored.

Errors on ParseServerData

    • if the file name cannot be opened, the function throws an invalid_argument exception

    • if any of the input lines has a command other than leave or join, the function throws a domain_error exception

void PrintAll(std::ostream &out, const ServerData &sd) Prints the contents of sd to out (not cout, the passed ostream out). Format is: server_name : user_name user_name … user_name server_name : user_name user_name … user_name


There is a '\n' after each line including the last

set<string> AllServers(const ServerData &sd) Returns a set<string> which is the set of all servers in the sd

set<string> AllUsers(const ServerData &sd)

Returns a set<string> which is the set of all users on any server in the sd

set<string> HasConnections(const ServerData &sd, UserName un) This function returns a set<string> of all the server names in sd that the user un is currently connected to. Note that the return set could be empty.

set<string> HasUsers(const ServerData &sd, ServerName sn)

This function returns a set<string> of all the user names in the server sn that are currently connected in sn. Note that the return set could be empty.

void BalanceServers(ServerData &sd, ServerName sn1, ServerName sn2)

This function tries to balance the number of users that are connected to server sn1 and sn2. If a user is connected to both servers, then they are not moved. All the users that are only connected to one of the 2 servers are moved in the following fashion. These users are sorted alphabetically by their name, and the first half are moved to server sn1, and the other half are moved to server sn2. (Note: if there are an odd number N of users, then N/2 +1 users are moved to sn1.)

void CleanAndBalance(ServerData &sd)

This function first removes all duplicate users from sd. Then the unique users are moved around in the following way.

    1. All the user names and server names are sorted alphabetically
    2. The users are distributed to servers in a round-robin fashion in alphabetical order of server and user names

For example, assume there are 3 servers named x,y,z and 8 users named a,b,c,d,e,f,g,h. Note we already sorted both lists (which you would have to do).
    • users a,d,g will be moved to server x, users b,e,h will be moved to server y and users c,f will be moved to server z

Deliverables

proj07proj07_functions.cpp -- your completion of the functions described above.

Only proj07/proj07_functions.cpp is turned in to Mimir.
    1. Remember to include your section, the date, project number and comments.

    2. Please be sure to use the specified directory and file name.

Manual Grading

In lab05 you worked with Code Style. The TAs will apply the things that you learned in your Code Review lesson on the code you submit. 4 points are reserved (out of 104) for this.

Assignment Notes

    1. Mimir allows us to test the functions in proj07_functions.cpp individually and we will do that.

    2. We provide a pro07_main.cpp to test your code which you can modify for your own testing, but only proj07_functions.cpp needs to be turned into Mimir
    3. proj07_functions.h is provided in the project07 directory. It will be used in testing. When we do testing, we will use the file we provide. If you change and submit your own version, Mimir will ignore your version and use the file originally provided.

    4. Algorithms/iterators are your friends here! Check out the following:

        a. set_intersection, things that are common in two sets

        b. set_symmetric_difference, opposite of intersection (unique elements from each set).
        c. copy_n, copy n elements from one set to another

        d. the map.find function (different from the regular find, utilizes ordered search)
        e. inserter iterator, adds elements to a map/set
        f. be on the lookout for others as well. Let the algorithms do the work!