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

// Thread-ID -- Get a unique thread ID
// Copyright 2016 Ruud van Asseldonk
//
// Licensed under either the Apache License, Version 2.0, or the MIT license, at
// your option. A copy of both licenses has been included in the root of the
// repository.

//! Thread-ID: get a unique ID for the current thread.
//!
//! For diagnostics and debugging it can often be useful to get an ID that is
//! different for every thread. This crate provides that functionality.
//!
//! # Example
//!
//! ```
//! use std::thread;
//! use thread_id;
//!
//! let handle = thread::spawn(move || {
//!     println!("spawned thread has id {}", thread_id::get());
//! });
//!
//! println!("main thread has id {}", thread_id::get());
//!
//! handle.join().unwrap();
//! ```

#![warn(missing_docs)]

#[cfg(unix)]
extern crate libc;

#[cfg(windows)]
extern crate winapi;

#[cfg(target_os = "redox")]
extern crate syscall;

/// Returns a number that is unique to the calling thread.
///
/// Calling this function twice from the same thread will return the same
/// number. Calling this function from a different thread will return a
/// different number.
#[inline]
pub fn get() -> usize {
    get_internal()
}

#[cfg(all(
    unix,
    not(any(
        target_os = "macos",
        target_os = "ios",
        target_os = "tvos",
        target_os = "watchos"
    ))
))]
#[inline]
fn get_internal() -> usize {
    unsafe { libc::pthread_self() as usize }
}

#[cfg(all(
    unix,
    any(
        target_os = "macos",
        target_os = "ios",
        target_os = "tvos",
        target_os = "watchos"
    )
))]
#[inline]
fn get_internal() -> usize {
    let mut tid: u64 = 0;
    unsafe {
        libc::pthread_threadid_np(libc::pthread_self(), &mut tid as *mut u64);
    };
    tid as usize
}

#[cfg(windows)]
#[inline]
fn get_internal() -> usize {
    unsafe { winapi::um::processthreadsapi::GetCurrentThreadId() as usize }
}

#[cfg(target_os = "redox")]
#[inline]
fn get_internal() -> usize {
    // Each thread has a separate pid on Redox.
    syscall::getpid().unwrap()
}

#[cfg(all(
    target_arch = "wasm32",
    target_vendor = "unknown",
    target_os = "unknown",
    not(target_feature = "atomics"),
))]
#[inline]
fn get_internal() -> usize {
    0
}

#[cfg(all(
    target_arch = "wasm32",
    target_vendor = "unknown",
    target_os = "unknown",
    target_feature = "atomics",
))]
#[inline]
fn get_internal() -> usize {
    use std::sync::atomic::{AtomicUsize, Ordering};

    static COUNTER: AtomicUsize = AtomicUsize::new(0);

    thread_local! {
        static ID: usize = COUNTER.fetch_add(1, Ordering::Relaxed);
    }

    ID.with(|id| *id)
}

#[test]
fn distinct_threads_have_distinct_ids() {
    use std::sync::mpsc;
    use std::thread;

    let (tx, rx) = mpsc::channel();
    thread::spawn(move || tx.send(::get()).unwrap()).join().unwrap();

    let main_tid = ::get();
    let other_tid = rx.recv().unwrap();
    assert!(main_tid != other_tid);
}