tiny_http 0.1.0

Low level HTTP server library
Documentation 
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

// Copyright 2015 The tiny-http Contributors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::sync::{Arc, Mutex};
use std::sync::mpsc::Sender;
use std::sync::atomic::{Ordering, AtomicUsize};
use std::sync::mpsc::channel;
use std::collections::VecDeque;
use std::thread;

/// Manages a collection of threads.
///
/// A new thread is created every time all the existing threads are full.
/// Any idle thread will automatically die after a few seconds.
pub struct TaskPool {
    free_tasks: Arc<Mutex<VecDeque<Sender<Box<FnMut() + Send>>>>>,
    active_tasks: Arc<AtomicUsize>,
}

/// Minimum number of active threads.
static MIN_THREADS: usize = 4;

struct Registration {
    nb: Arc<AtomicUsize>
}

impl Registration {
    fn new(nb: Arc<AtomicUsize>) -> Registration {
        nb.fetch_add(1, Ordering::Relaxed);
        Registration { nb: nb }
    }
}

impl Drop for Registration {
    fn drop(&mut self) {
        self.nb.fetch_sub(1, Ordering::Relaxed);
    }
}

impl TaskPool {
    pub fn new() -> TaskPool {
        let pool = TaskPool {
            free_tasks: Arc::new(Mutex::new(VecDeque::new())),
            active_tasks: Arc::new(AtomicUsize::new(0)),
        };

        for _ in 0..MIN_THREADS {
            pool.add_thread(None)
        }

        pool
    }

    /// Executes a function in a thread.
    /// If no thread is available, spawns a new one.
    pub fn spawn(&self, mut code: Box<FnMut() + Send>) {
        let mut queue = self.free_tasks.lock().unwrap();

        loop {
            if let Some(sender) = queue.pop_front() {
                match sender.send(code) {
                    Ok(_) => return,
                    Err(err) => { code = err.0; continue; }
                };
            } else {
                self.add_thread(Some(code));
                return;
            }
        }
    }

    fn add_thread(&self, initial_fn: Option<Box<FnMut() + Send>>) {
        let queue = self.free_tasks.clone();
        let active_tasks = self.active_tasks.clone();

        thread::spawn(move || {
            let active_tasks = active_tasks;
            let _ = Registration::new(active_tasks.clone());

            if initial_fn.is_some() {
                let mut f = initial_fn.unwrap();
                f();
            }

            let mut timeout_cycles = 5000 / 3;

            loop {
                let (tx, rx) = channel();

                {
                    let mut queue = queue.lock().unwrap();
                    queue.push_back(tx);
                }

                thread::sleep_ms(3);

                match rx.try_recv() {
                    Ok(mut f) => {
                        f();
                        timeout_cycles = 5000 / 3;
                    },
                    _ => {
                        timeout_cycles -= 1;

                        if timeout_cycles == 0 && active_tasks.load(Ordering::Relaxed)
                                                  >= MIN_THREADS
                        {
                            break;
                        }
                    }
                };
            }
        });
    }
}

impl Drop for TaskPool {
    fn drop(&mut self) {
        self.active_tasks.store(999999999, Ordering::Relaxed);
    }
}