made webserver multithreaded.

the_book/http_server/src/bin/main.rs

@@ -0,0 +1,64 @@
+use http_server::ThreadPool;
+
+use std::fs;
+use std::time::Duration;
+use std::thread;
+use std::io::prelude::*;
+use std::net::TcpListener;
+use std::net::TcpStream;
+
+enum ContinueServer {
+    Continue,
+    Stop,
+}
+
+fn main() {
+    let listener = TcpListener::bind("127.0.0.1:7878").unwrap();
+    let pool = ThreadPool::new(4);
+
+    for stream in listener.incoming() {
+        let stream = stream.unwrap();
+
+        //TODO: make the pool gracefully shutdown if handle_connection returns ContinueServer::Stop.
+        //to make the code generic, probably need to have pool.execute return a dynamic box?
+        pool.execute(|| { handle_connection(stream); });
+    }
+}
+
+fn handle_connection(mut stream: TcpStream) -> ContinueServer {
+    let mut buffer = [0; 1024];
+
+    stream.read(&mut buffer).unwrap();
+
+    //The different paths we want to watch for.
+    let get = b"GET / HTTP/1.1\r\n";
+    let sleep = b"GET /sleep HTTP/1.1\r\n";
+    let stop = b"GET /stop HTTP/1.1\r\n";
+
+    //return different paths, if nothing matches, returns 404.
+    let (status_line, filename, continue_after_request) = if buffer.starts_with(get) {
+        ("HTTP/1.1 200 OK", "hello.html", ContinueServer::Continue)
+    } else if buffer.starts_with(sleep) {
+        thread::sleep(Duration::from_secs(5));
+        ("HTTP/1.1 200 OK", "hello.html", ContinueServer::Continue)
+    } else  if buffer.starts_with(stop) {
+        ("HTTP/1.1 200 OK", "stopped.html", ContinueServer::Stop)
+    } else {
+        ("HTTP/1.1 404 NOT FOUND", "404.html", ContinueServer::Continue)
+    };
+
+    let contents = fs::read_to_string(filename).unwrap();
+    let response = format!(
+        "{}\r\nContent-Length: {}\r\n\r\n{}",
+        status_line,
+        contents.len(),
+        contents,
+    );
+
+    stream.write_all(response.as_bytes()).unwrap();
+    stream.flush().unwrap();
+
+    //returns whether the server should gracefully shutdown after this request, or keep going.
+    //TODO: not implemented.
+    continue_after_request
+}

the_book/http_server/src/lib.rs

@@ -0,0 +1,117 @@
+use std::sync::mpsc;
+use std::sync::Arc;
+use std::sync::Mutex;
+use std::thread;
+
+type Job = Box<dyn FnOnce() + Send + 'static>;
+
+//In order to be able to tell the workers to terminate, need to be able to send a terminate message.
+enum Message {
+    NewJob(Job),
+    Terminate,
+}
+
+pub struct ThreadPool {
+    workers: Vec<Worker>,
+    sender: mpsc::Sender<Message>,
+}
+
+impl ThreadPool {
+    /// create a new threadpool
+    ///
+    /// the size is the number of threads in the pool
+    ///
+    /// # Panics
+    ///
+    /// the 'new' function will panic if size is zero.
+    pub fn new(size: usize) -> ThreadPool {
+        assert!(size > 0);
+
+        let (sender, receiver) = mpsc::channel();
+
+        //reciever is passed out to a bunch of threads, so need to wrap it in an Arc<Mutex<>> to
+        //share it.
+        let receiver = Arc::new(Mutex::new(receiver));
+
+        let mut workers = Vec::with_capacity(size);
+
+        for id in 0..size {
+            workers.push(Worker::new(id, Arc::clone(&receiver)));
+        }
+
+        ThreadPool { workers, sender }
+    }
+
+    ///passes the given closure to an arbitrary thread to execute.
+    pub fn execute<F>(&self, f: F)
+    where
+        F: FnOnce() + Send + 'static,
+    {
+        let job = Box::new(f);
+
+        //we send the closure as a message, and whichever thread happens to check its messages
+        //next starts executing it.
+        self.sender.send(Message::NewJob(job)).unwrap();
+    }
+}
+
+//this allows a graceful shutdown of the program, serving all remaining requests before
+//terminating.
+impl Drop for ThreadPool {
+    fn drop(&mut self) {
+        println!("Sending terminate message to all workers.");
+
+        //we have to have two seperate loops because we dont send a message to a specific thread,
+        //we send it to whoever happens to be the first to grab it. Therefore, we could send our
+        //first message, thread 2 and then be stuck in a deadlock waiting for thread 3 to stop,
+        //which it never will as only thread 2 has been told to stop.
+        //
+        //So, we have to send all the messages and *then* join all the threads.
+        for _ in &self.workers {
+            self.sender.send(Message::Terminate).unwrap();
+        }
+
+        println!("Shutting down all workers.");
+
+        for worker in &mut self.workers {
+            println!("Shutting down worker {}.", worker.id);
+
+            if let Some(thread) = worker.thread.take() {
+                thread.join().unwrap()
+            }
+        }
+    }
+}
+
+struct Worker {
+    id: usize,
+    thread: Option<thread::JoinHandle<()>>,
+}
+
+impl Worker {
+    fn new(id: usize, reciever: Arc<Mutex<mpsc::Receiver<Message>>>) -> Worker {
+        //the call to recv() blocks untill a new message is avalible, so this thing isnt just
+        //spinning its wheels in an infinite loop.
+        let thread = thread::spawn(move || loop {
+            let message = reciever.lock().unwrap().recv().unwrap();
+
+            match message {
+                Message::NewJob(job) => {
+                    job();
+
+                    println!("Worker {} got job, executing.", id);
+                }
+                Message::Terminate => {
+                    println!("Worker {} was told to terminate.", id);
+
+                    break;
+                }
+            }
+        });
+
+        Worker {
+            id,
+            thread: Some(thread),
+        }
+    }
+}

the_book/http_server/src/main.rs

@@ -1,46 +0,0 @@
-use std::fs;
-use std::time::Duration;
-use std::thread;
-use std::io::prelude::*;
-use std::net::TcpListener;
-use std::net::TcpStream;
-
-fn main() {
-    let listener = TcpListener::bind("127.0.0.1:7878").unwrap();
-
-    for stream in listener.incoming() {
-        let stream = stream.unwrap();
-        println!("Connection Established!");
-        handle_connection(stream);
-    }
-}
-
-fn handle_connection(mut stream: TcpStream) {
-    let mut buffer = [0; 1024];
-
-    stream.read(&mut buffer).unwrap();
-    println!("Request: {}", String::from_utf8_lossy(&buffer[..]));
-
-    let get = b"GET / HTTP/1.1\r\n";
-    let sleep = b"GET /sleep HTTP/1.1\r\n";
-
-    let (status_line, filename) = if buffer.starts_with(get) {
-        ("HTTP/1.1 200 OK", "hello.html")
-    } else if buffer.starts_with(sleep) {
-        thread::sleep(Duration::from_secs(5));
-        ("HTTP/1.1 200 OK", "hello.html")
-    } else {
-        ("HTTP/1.1 404 NOT FOUND", "404.html")
-    };
-
-    let contents = fs::read_to_string(filename).unwrap();
-    let response = format!(
-        "{}\r\nContent-Length: {}\r\n\r\n{}",
-        status_line,
-        contents.len(),
-        contents,
-    );
-
-    stream.write_all(response.as_bytes()).unwrap();
-    stream.flush().unwrap();
-}

the_book/http_server/stopped.html

@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8">
+    <title>Bye!</title>
+  </head>
+  <body>
+    <h1>Bye!</h1>
+    <p>Bye from Rust!</p>
+  </body>
+</html>