1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
use std::{io, num::NonZeroUsize, time::Duration};

use actix_rt::net::TcpStream;
use tokio::sync::mpsc::{unbounded_channel, UnboundedReceiver, UnboundedSender};

use crate::{
    server::ServerCommand,
    service::{InternalServiceFactory, ServerServiceFactory, StreamNewService},
    socket::{create_mio_tcp_listener, MioListener, MioTcpListener, StdTcpListener, ToSocketAddrs},
    worker::ServerWorkerConfig,
    Server,
};

/// Multipath TCP (MPTCP) preference.
///
/// Currently only useful on Linux.
///
#[cfg_attr(target_os = "linux", doc = "Also see [`ServerBuilder::mptcp()`].")]
#[derive(Debug, Clone)]
pub enum MpTcp {
    /// MPTCP will not be used when binding sockets.
    Disabled,

    /// MPTCP will be attempted when binding sockets. If errors occur, regular TCP will be
    /// attempted, too.
    TcpFallback,

    /// MPTCP will be used when binding sockets (with no fallback).
    NoFallback,
}

/// [Server] builder.
pub struct ServerBuilder {
    pub(crate) threads: usize,
    pub(crate) token: usize,
    pub(crate) backlog: u32,
    pub(crate) factories: Vec<Box<dyn InternalServiceFactory>>,
    pub(crate) sockets: Vec<(usize, String, MioListener)>,
    pub(crate) mptcp: MpTcp,
    pub(crate) exit: bool,
    pub(crate) listen_os_signals: bool,
    pub(crate) cmd_tx: UnboundedSender<ServerCommand>,
    pub(crate) cmd_rx: UnboundedReceiver<ServerCommand>,
    pub(crate) worker_config: ServerWorkerConfig,
}

impl Default for ServerBuilder {
    fn default() -> Self {
        Self::new()
    }
}

impl ServerBuilder {
    /// Create new Server builder instance
    pub fn new() -> ServerBuilder {
        let (cmd_tx, cmd_rx) = unbounded_channel();

        ServerBuilder {
            threads: std::thread::available_parallelism().map_or(2, NonZeroUsize::get),
            token: 0,
            factories: Vec::new(),
            sockets: Vec::new(),
            backlog: 2048,
            mptcp: MpTcp::Disabled,
            exit: false,
            listen_os_signals: true,
            cmd_tx,
            cmd_rx,
            worker_config: ServerWorkerConfig::default(),
        }
    }

    /// Sets number of workers to start.
    ///
    /// See [`bind()`](Self::bind()) for more details on how worker count affects the number of
    /// server factory instantiations.
    ///
    /// The default worker count is the determined by [`std::thread::available_parallelism()`]. See
    /// its documentation to determine what behavior you should expect when server is run.
    ///
    /// `num` must be greater than 0.
    ///
    /// # Panics
    ///
    /// Panics if `num` is 0.
    pub fn workers(mut self, num: usize) -> Self {
        assert_ne!(num, 0, "workers must be greater than 0");
        self.threads = num;
        self
    }

    /// Set max number of threads for each worker's blocking task thread pool.
    ///
    /// One thread pool is set up **per worker**; not shared across workers.
    ///
    /// # Examples:
    /// ```
    /// # use actix_server::ServerBuilder;
    /// let builder = ServerBuilder::new()
    ///     .workers(4) // server has 4 worker thread.
    ///     .worker_max_blocking_threads(4); // every worker has 4 max blocking threads.
    /// ```
    ///
    /// See [tokio::runtime::Builder::max_blocking_threads] for behavior reference.
    pub fn worker_max_blocking_threads(mut self, num: usize) -> Self {
        self.worker_config.max_blocking_threads(num);
        self
    }

    /// Set the maximum number of pending connections.
    ///
    /// This refers to the number of clients that can be waiting to be served. Exceeding this number
    /// results in the client getting an error when attempting to connect. It should only affect
    /// servers under significant load.
    ///
    /// Generally set in the 64-2048 range. Default value is 2048.
    ///
    /// This method should be called before `bind()` method call.
    pub fn backlog(mut self, num: u32) -> Self {
        self.backlog = num;
        self
    }

    /// Sets MultiPath TCP (MPTCP) preference on bound sockets.
    ///
    /// Multipath TCP (MPTCP) builds on top of TCP to improve connection redundancy and performance
    /// by sharing a network data stream across multiple underlying TCP sessions. See [mptcp.dev]
    /// for more info about MPTCP itself.
    ///
    /// MPTCP is available on Linux kernel version 5.6 and higher. In addition, you'll also need to
    /// ensure the kernel option is enabled using `sysctl net.mptcp.enabled=1`.
    ///
    /// This method will have no effect if called after a `bind()`.
    ///
    /// [mptcp.dev]: https://www.mptcp.dev
    #[cfg(target_os = "linux")]
    pub fn mptcp(mut self, mptcp_enabled: MpTcp) -> Self {
        self.mptcp = mptcp_enabled;
        self
    }

    /// Sets the maximum per-worker number of concurrent connections.
    ///
    /// All socket listeners will stop accepting connections when this limit is reached for
    /// each worker.
    ///
    /// By default max connections is set to a 25k per worker.
    pub fn max_concurrent_connections(mut self, num: usize) -> Self {
        self.worker_config.max_concurrent_connections(num);
        self
    }

    #[doc(hidden)]
    #[deprecated(since = "2.0.0", note = "Renamed to `max_concurrent_connections`.")]
    pub fn maxconn(self, num: usize) -> Self {
        self.max_concurrent_connections(num)
    }

    /// Sets flag to stop Actix `System` after server shutdown.
    ///
    /// This has no effect when server is running in a Tokio-only runtime.
    pub fn system_exit(mut self) -> Self {
        self.exit = true;
        self
    }

    /// Disables OS signal handling.
    pub fn disable_signals(mut self) -> Self {
        self.listen_os_signals = false;
        self
    }

    /// Timeout for graceful workers shutdown in seconds.
    ///
    /// After receiving a stop signal, workers have this much time to finish serving requests.
    /// Workers still alive after the timeout are force dropped.
    ///
    /// By default shutdown timeout sets to 30 seconds.
    pub fn shutdown_timeout(mut self, sec: u64) -> Self {
        self.worker_config
            .shutdown_timeout(Duration::from_secs(sec));
        self
    }

    /// Adds new service to the server.
    ///
    /// Note that, if a DNS lookup is required, resolving hostnames is a blocking operation.
    ///
    /// # Worker Count
    ///
    /// The `factory` will be instantiated multiple times in most scenarios. The number of
    /// instantiations is number of [`workers`](Self::workers()) × number of sockets resolved by
    /// `addrs`.
    ///
    /// For example, if you've manually set [`workers`](Self::workers()) to 2, and use `127.0.0.1`
    /// as the bind `addrs`, then `factory` will be instantiated twice. However, using `localhost`
    /// as the bind `addrs` can often resolve to both `127.0.0.1` (IPv4) _and_ `::1` (IPv6), causing
    /// the `factory` to be instantiated 4 times (2 workers × 2 bind addresses).
    ///
    /// Using a bind address of `0.0.0.0`, which signals to use all interfaces, may also multiple
    /// the number of instantiations in a similar way.
    ///
    /// # Errors
    ///
    /// Returns an `io::Error` if:
    /// - `addrs` cannot be resolved into one or more socket addresses;
    /// - all the resolved socket addresses are already bound.
    pub fn bind<F, U, N>(mut self, name: N, addrs: U, factory: F) -> io::Result<Self>
    where
        F: ServerServiceFactory<TcpStream>,
        U: ToSocketAddrs,
        N: AsRef<str>,
    {
        let sockets = bind_addr(addrs, self.backlog, &self.mptcp)?;

        tracing::trace!("binding server to: {sockets:?}");

        for lst in sockets {
            let token = self.next_token();

            self.factories.push(StreamNewService::create(
                name.as_ref().to_string(),
                token,
                factory.clone(),
                lst.local_addr()?,
            ));

            self.sockets
                .push((token, name.as_ref().to_string(), MioListener::Tcp(lst)));
        }

        Ok(self)
    }

    /// Adds service to the server using a socket listener already bound.
    ///
    /// # Worker Count
    ///
    /// The `factory` will be instantiated multiple times in most scenarios. The number of
    /// instantiations is: number of [`workers`](Self::workers()).
    pub fn listen<F, N: AsRef<str>>(
        mut self,
        name: N,
        lst: StdTcpListener,
        factory: F,
    ) -> io::Result<Self>
    where
        F: ServerServiceFactory<TcpStream>,
    {
        lst.set_nonblocking(true)?;
        let addr = lst.local_addr()?;

        let token = self.next_token();
        self.factories.push(StreamNewService::create(
            name.as_ref().to_string(),
            token,
            factory,
            addr,
        ));

        self.sockets
            .push((token, name.as_ref().to_string(), MioListener::from(lst)));

        Ok(self)
    }

    /// Starts processing incoming connections and return server controller.
    pub fn run(self) -> Server {
        if self.sockets.is_empty() {
            panic!("Server should have at least one bound socket");
        } else {
            tracing::info!("starting {} workers", self.threads);
            Server::new(self)
        }
    }

    fn next_token(&mut self) -> usize {
        let token = self.token;
        self.token += 1;
        token
    }
}

#[cfg(unix)]
impl ServerBuilder {
    /// Adds new service to the server using a UDS (unix domain socket) address.
    ///
    /// # Worker Count
    ///
    /// The `factory` will be instantiated multiple times in most scenarios. The number of
    /// instantiations is: number of [`workers`](Self::workers()).
    pub fn bind_uds<F, U, N>(self, name: N, addr: U, factory: F) -> io::Result<Self>
    where
        F: ServerServiceFactory<actix_rt::net::UnixStream>,
        N: AsRef<str>,
        U: AsRef<std::path::Path>,
    {
        // The path must not exist when we try to bind.
        // Try to remove it to avoid bind error.
        if let Err(err) = std::fs::remove_file(addr.as_ref()) {
            // NotFound is expected and not an issue. Anything else is.
            if err.kind() != std::io::ErrorKind::NotFound {
                return Err(err);
            }
        }

        let lst = crate::socket::StdUnixListener::bind(addr)?;
        self.listen_uds(name, lst, factory)
    }

    /// Adds new service to the server using a UDS (unix domain socket) listener already bound.
    ///
    /// Useful when running as a systemd service and a socket FD is acquired externally.
    ///
    /// # Worker Count
    ///
    /// The `factory` will be instantiated multiple times in most scenarios. The number of
    /// instantiations is: number of [`workers`](Self::workers()).
    pub fn listen_uds<F, N: AsRef<str>>(
        mut self,
        name: N,
        lst: crate::socket::StdUnixListener,
        factory: F,
    ) -> io::Result<Self>
    where
        F: ServerServiceFactory<actix_rt::net::UnixStream>,
    {
        use std::net::{IpAddr, Ipv4Addr};

        lst.set_nonblocking(true)?;

        let token = self.next_token();
        let addr = crate::socket::StdSocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), 8080);

        self.factories.push(StreamNewService::create(
            name.as_ref().to_string(),
            token,
            factory,
            addr,
        ));

        self.sockets
            .push((token, name.as_ref().to_string(), MioListener::from(lst)));

        Ok(self)
    }
}

pub(super) fn bind_addr<S: ToSocketAddrs>(
    addr: S,
    backlog: u32,
    mptcp: &MpTcp,
) -> io::Result<Vec<MioTcpListener>> {
    let mut opt_err = None;
    let mut success = false;
    let mut sockets = Vec::new();

    for addr in addr.to_socket_addrs()? {
        match create_mio_tcp_listener(addr, backlog, mptcp) {
            Ok(lst) => {
                success = true;
                sockets.push(lst);
            }
            Err(err) => opt_err = Some(err),
        }
    }

    if success {
        Ok(sockets)
    } else if let Some(err) = opt_err.take() {
        Err(err)
    } else {
        Err(io::Error::new(
            io::ErrorKind::Other,
            "Can not bind to address.",
        ))
    }
}