Write a program [webserver.c](./webserver.c) using threads and sockets supporting HTTP GET requests which works in

the following way:

- It creates a pool of threads in the beginning

- Main thread waits on `epoll_wait` for any I/O on sockets

- It stores the requests in a message queue used by all the threads.

- Each client is supposed to go through following stages

- READING_REQUEST

- HEADER_PARSING

- READING_DISKFILE

- WRITING_HEADER

- WRITING_BODY

- After WRITING_HEADER stage, client cycles between READING_DISKFILE and WRITING_BODY stage until full file is transferred

- Connection is not closed until server receives an EOF (i.e. client itself has closed the connection).

- I/O on sockets is non blocking, but reading from file is blocking since it'll always succeed.

Testing is done using `httpref` which can be installed via `sudo apt install httpref`

Some snapshots for the statistics can be found here :

1. Number of connections : 100, Rate : 10, File size : 1450 bytes

<img src="./statistics/conn_100_rate_10.png">

2. Number of connections : 3000, Rate : 50, File size : 1450 bytes

<img src="./statistics/conn_3000_rate_50.png">

3. Number of connections : 10000, Rate : 50, File size : 1509793 bytes (15.1 MB)

<img src="./statistics/conn_10000_rate_50.png">

<img src="./demo.gif">

- Linux kernal v4.15.0 (or higher)

result[n].src = "./static/images/" + name + ".png";

if(errno != ECONNRESET && errno != EBADF)

errorExit("read failed");

if(errno != ECONNRESET && errno != EBADF)

errorExit("write failed");

int Close(int fd){

printf("Closing %d\n", fd);

if(close(fd) < 0 ){

if(errno != EBADF)

errorExit("close failed");

}

return SUCCESS;

}

if (strcmp(extension, "mp3") == 0) {

char *getTimestamp(){

char *buf = (char*)malloc(sizeof(char) * 1000);

time_t now = time(0);

struct tm tm = *gmtime(&now);

strftime(buf, sizeof buf, "%a, %d %b %Y %H:%M:%S %Z", &tm);

return buf;

}

int Close(int fd);

char *getTimestamp();