Servers

In this section, you will implement several different servers. With the conditional compilation preprocessor directives (i.e. the #ifdef directives), we only need to change how we call the request handler in each of these different servers.

Fork server

Implement forkserver. You won’t be writing much new code.

• The child process should call request_handler with the client socket fd. After serving a response, the child process will terminate.
• The parent process will continue listening and accepting incoming connections. It will not wait for the child.
• Remember to close sockets appropriately in both the parent and child process.

For me, this step required to write five lines of code. If you think you need to write considerably more, please get in contact.

Thread server

Implement threadserver.

• Create a new pthread to send the proper response to the client.
• The original thread continues listening and accepting incoming connections. It will not join with the new thread.

For me, this step required to write less than 30 lines of code. If you think you need to write considerably more, please get in contact.

Pool server

Implement poolserver.

• Your thread pool should be able to concurrently serve exactly –num-threads clients and no more. Note that we typically use –num-threads + 1 threads in our program. The original thread is responsible for accepting client connections in a while loop and dispatching the associated requests to be handled by the threads in the thread pool.
• Begin by looking at the functions in wq.h. You don’t need to implement a work queue, its implementation is provided to you in wq.c.
  • The original thread (i.e. the thread you started the httpserver program with) should wq_push the client socket file descriptors received from accept into the wq_t work_queue declared at the top of httpserver.c and defined in wq.h.
  • Then, threads in the thread pool should use wq_pop to get the next client socket file descriptor to handle.
• You’ll need to make your server spawn --num-threads new threads which will spin in a loop doing the following:
  • Make blocking calls to wq_pop for the next client socket file descriptor.
  • After successfully popping a to-be-served client socket fd, call the appropriate request handler to handle the client request.

For me, this step required to write less than 15 lines of code. If you think you need to write considerably more, please get in contact.

Next document: Performance.