INSTALLATION

SERVER

$ chmod +x first_time_run.sh
$ ./first_time_run.sh
# Run
$ ./run.sh

• You may need to increase the Open Files Limitation to a larger number (i.e. 20000) in local environment to handle more connections.

WRK (FOR PERFORMANCE TESTING)

$ sudo apt-get install build-essential libssl-dev git -y
$ git clone https://github.com/wg/wrk.git wrk
$ cd wrk
$ sudo make
# move the executable to somewhere in your PATH, ex:
$ sudo cp wrk /usr/local/bin

FEATURES SUPPORTED

• Multiple clients to connect to the server at the same time.
• Supports HTTP/1.1.
• Get the response by request type and endpoint.
  • "GET /" : return index.html page.
  • "GET /{some text file}" : return any pre-loaded files to the client.
• Get files (image, text, ...)
  • "GET /{fileName}": return that file to the client.

EXPLANATION

• Maintains a file descriptor for listening socket called socketMaster. The socketMaster is responsible for listening port PORT (PORT = 2101 by default).

• To monitor events on the file descriptors, I use epoll that is a data structure (Red-Black Tree) to monitor events on file descriptors.

• First, creates an epollContext with epoll_create() and registers socketMaster to the epollContext.

• epoll_wait() is used to get the file descriptors that are ready for I/O.

• When there is any I/O event on the socketMaster, that means there is a connection is coming.

• Then accept() to open another socket to deal with that connection and register it to the epollContext.

• If an event is seen on the file descriptor other than socketMaster, base on the type of event, it will handle it.

  • When an EPOLLIN event occurs, then there is a request, I will handle the request and send some response to the client via that corresponding socket.
  • When an EPOLLERR or EPOLLHUP event occurs, I will close that connection.

• When the server is starting up, I load some static HTML files (JS too) to respond quickly.

• The server supports transferring files. If you open /about.html page, you can see the browser is loading about.css, about.js and images.

• I used a Thread Pool to handle "heavy" request (may be transferring a file, search in database, ...).
  First the pool is created with X thread(s) as X workers, which are infinitely looking into a mutex-locked queue of tasks.
  Whenever a worker takes a task from the queue, that worker executes it.

• This event-driven architecture allows the server to handle many connections and requests efficiently.

PERFORMANCE TESTING

$ ./wrk -t5 -c10000 -d30s http://127.0.0.1:2101  
# Testing with 10000 connections kept openned within 30s by 5 threads