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

// Copyright 2016 Amanieu d'Antras
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

//! This library exposes a low-level API for creating your own efficient
//! synchronization primitives.
//!
//! # The parking lot
//!
//! To keep synchronization primitives small, all thread queuing and suspending
//! functionality is offloaded to the *parking lot*. The idea behind this is based
//! on the Webkit [`WTF::ParkingLot`](https://webkit.org/blog/6161/locking-in-webkit/)
//! class, which essentially consists of a hash table mapping of lock addresses
//! to queues of parked (sleeping) threads. The Webkit parking lot was itself
//! inspired by Linux [futexes](http://man7.org/linux/man-pages/man2/futex.2.html),
//! but it is more powerful since it allows invoking callbacks while holding a
//! queue lock.
//!
//! There are two main operations that can be performed on the parking lot:
//!
//!  - *Parking* refers to suspending the thread while simultaneously enqueuing it
//! on a queue keyed by some address.
//! - *Unparking* refers to dequeuing a thread from a queue keyed by some address
//! and resuming it.
//!
//! See the documentation of the individual functions for more details.
//!
//! # Building custom synchronization primitives
//!
//! Building custom synchronization primitives is very simple since the parking
//! lot takes care of all the hard parts for you. A simple example for a
//! custom primitive would be to integrate a `Mutex` inside another data type.
//! Since a mutex only requires 2 bits, it can share space with other data.
//! For example, one could create an `ArcMutex` type that combines the atomic
//! reference count and the two mutex bits in the same atomic word.

#![warn(missing_docs)]
#![cfg_attr(all(feature = "nightly", target_os = "linux"), feature(integer_atomics))]

extern crate rand;
extern crate smallvec;

#[cfg(feature = "deadlock_detection")]
extern crate backtrace;
#[cfg(feature = "deadlock_detection")]
extern crate petgraph;
#[cfg(feature = "deadlock_detection")]
extern crate thread_id;

#[cfg(unix)]
extern crate libc;

#[cfg(windows)]
extern crate winapi;

#[cfg(all(feature = "nightly", target_os = "linux"))]
#[path = "thread_parker/linux.rs"]
mod thread_parker;
#[cfg(all(unix, not(all(feature = "nightly", target_os = "linux"))))]
#[path = "thread_parker/unix.rs"]
mod thread_parker;
#[cfg(windows)]
#[path = "thread_parker/windows/mod.rs"]
mod thread_parker;
#[cfg(not(any(windows, unix)))]
#[path = "thread_parker/generic.rs"]
mod thread_parker;

mod util;
mod spinwait;
mod word_lock;
mod parking_lot;

pub use parking_lot::{FilterOp, ParkResult, ParkToken, RequeueOp, UnparkResult, UnparkToken};
pub use parking_lot::{DEFAULT_PARK_TOKEN, DEFAULT_UNPARK_TOKEN};
pub use parking_lot::{park, unpark_all, unpark_filter, unpark_one, unpark_requeue};
pub use spinwait::SpinWait;
pub use parking_lot::deadlock;