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use std::{
io::{self, Read, Write},
net, num,
panic::{catch_unwind, AssertUnwindSafe},
rc::Rc,
sync::Arc,
};
use rayon::ThreadPoolBuilder;
use crate::{
http::{
handler::{trigger, Handler},
request::Request,
response::IntoResponse,
StatusCode,
},
middleware::MiddlewareHandler,
router::{Router, RouterError},
Context,
};
/// Encapsulates functionality to serve HTTP requests.
pub struct Server {
listener: net::TcpListener,
router: Router,
ctx: Context,
global_middleware: Vec<MiddlewareHandler>,
num_threads: Option<usize>,
}
type ChainOperator = Rc<Box<dyn Fn(Request) -> Box<dyn IntoResponse>>>;
impl Server {
/// Binds the server to the provided address.
///
/// ```
/// use snx::{Server, router::Router};
///
/// let router = Router::builder("localhost").build().unwrap();
/// let global_middleware = vec![];
/// let server = Server::try_bind("127.0.0.1:2002", router, global_middleware).expect("failed to bind listener");
/// ```
pub fn try_bind(
addr: impl net::ToSocketAddrs,
router: Router,
ctx: Context,
global_middleware: Vec<MiddlewareHandler>,
) -> io::Result<Self> {
let listener = net::TcpListener::bind(addr)?;
Ok(Self {
listener,
num_threads: None,
router,
ctx,
global_middleware,
})
}
/// Starts serving incoming HTTP requests.
///
/// ```no_run
/// use snx::{Server, router::Router};
///
/// let router = Router::builder("localhost").build().unwrap();
/// Server::try_bind("127.0.0.1:2002", router, vec![])
/// .expect("failed to bind to listener")
/// .serve();
/// ```
pub fn serve(self) {
let num_threads = self.num_threads.unwrap_or(
std::thread::available_parallelism()
.map(num::NonZero::get)
.unwrap_or(4),
);
let pool = ThreadPoolBuilder::new()
.num_threads(num_threads)
.build()
.unwrap();
for connection in self.listener.incoming() {
match connection {
Ok(stream) => pool.install(|| self.handle_connection(stream)),
Err(e) => tracing::info!("client failed to connect: {e}"),
}
}
}
/// Sets the number of threads to be used in the threadpool.
///
/// ```
/// use snx::{Server, router::Router};
///
/// let router = Router::builder("localhost").build().unwrap();
/// let server = Server::try_bind("127.0.0.1:2002", router, vec![])
/// .expect("failed to bind to listener")
/// .num_threads(4);
/// ```
pub fn num_threads(mut self, amount: usize) -> Self {
self.num_threads = Some(amount);
self
}
/// Handles an incoming connection.
///
/// Reads data from the stream, parses it into a [Request], dispatches it to the router,
/// executes the associated handler and writes a response back to the stream.
fn handle_connection(&self, mut stream: net::TcpStream) {
let mut buffer = [0; 8192];
match stream.read(&mut buffer) {
Ok(bytes_read) => {
if bytes_read == 0 {
return;
}
let into_response: Box<dyn IntoResponse> =
match Request::try_parse_from_bytes(&buffer, stream.peer_addr().ok()) {
Ok(mut request) => {
let host = request.headers().get("host").unwrap();
match self.router.at(&request.method(), &host, &request.path()) {
Ok(route) => {
request.params = route.parameters;
self.execute(
route.route.handler().clone(),
route.route.middleware().clone(),
request,
)
}
Err(RouterError::NotFound) => self.execute(
Arc::new(Box::new(|_, _| StatusCode::NotFound)),
vec![],
request,
),
Err(RouterError::MethodNotAllowed) => self.execute(
Arc::new(Box::new(|_, _| StatusCode::MethodNotAllowed)),
vec![],
request,
),
}
}
Err(e) => {
tracing::warn!("could not parse request: {e}");
Box::new(StatusCode::BadRequest)
}
};
let _ = stream.write_all(
&into_response
.into_response()
.serialize_to_raw_http_response(),
);
}
Err(e) => tracing::warn!("could not read from client: {e}"),
}
}
/// Executes the given handler with the given middleware.
fn execute(
&self,
handler: Arc<Box<dyn Handler + Send + Sync>>,
middleware: Vec<MiddlewareHandler>,
request: Request,
) -> Box<dyn IntoResponse> {
let mut middleware = middleware.clone();
let ctx = self.ctx.clone();
let mut chain: Vec<ChainOperator> = Vec::with_capacity(middleware.len() + 1);
// first, add the actual handler call to the chain (this will be called last)
chain.push(Rc::new(Box::new(move |request: Request| {
catch_unwind(AssertUnwindSafe(|| {
trigger(ctx.clone(), request.clone(), handler.clone())
}))
.unwrap_or(Box::new(StatusCode::InternalServerError))
})));
// second, loop over all middleware for route (and global middleware) and add in reverse
// order.
middleware.extend_from_slice(&self.global_middleware);
for handler in middleware {
let ctx = self.ctx.clone();
let op = chain.last().unwrap().clone();
chain.push(Rc::new(Box::new(move |request: Request| {
(handler)(
ctx.clone(),
request.clone(),
Box::new({
let value = op.clone();
move || value(request.clone()).into_response()
}),
)
})));
}
// last, kick off the chain by calling the end of it (the outermost middleware)
chain.last().unwrap()(request)
}
}