vendor/parking_lot_core-0.7.2/src/lib.rs

   1 // Copyright 2016 Amanieu d'Antras
   2 //
   3 // Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
   4 // http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
   5 // http://opensource.org/licenses/MIT>, at your option. This file may not be
   6 // copied, modified, or distributed except according to those terms.
   7
   8 //! This library exposes a low-level API for creating your own efficient
   9 //! synchronization primitives.
  10 //!
  11 //! # The parking lot
  12 //!
  13 //! To keep synchronization primitives small, all thread queuing and suspending
  14 //! functionality is offloaded to the *parking lot*. The idea behind this is based
  15 //! on the Webkit [`WTF::ParkingLot`](https://webkit.org/blog/6161/locking-in-webkit/)
  16 //! class, which essentially consists of a hash table mapping of lock addresses
  17 //! to queues of parked (sleeping) threads. The Webkit parking lot was itself
  18 //! inspired by Linux [futexes](http://man7.org/linux/man-pages/man2/futex.2.html),
  19 //! but it is more powerful since it allows invoking callbacks while holding a
  20 //! queue lock.
  21 //!
  22 //! There are two main operations that can be performed on the parking lot:
  23 //!
  24 //!  - *Parking* refers to suspending the thread while simultaneously enqueuing it
  25 //! on a queue keyed by some address.
  26 //! - *Unparking* refers to dequeuing a thread from a queue keyed by some address
  27 //! and resuming it.
  28 //!
  29 //! See the documentation of the individual functions for more details.
  30 //!
  31 //! # Building custom synchronization primitives
  32 //!
  33 //! Building custom synchronization primitives is very simple since the parking
  34 //! lot takes care of all the hard parts for you. A simple example for a
  35 //! custom primitive would be to integrate a `Mutex` inside another data type.
  36 //! Since a mutex only requires 2 bits, it can share space with other data.
  37 //! For example, one could create an `ArcMutex` type that combines the atomic
  38 //! reference count and the two mutex bits in the same atomic word.
  39
  40 #![warn(missing_docs)]
  41 #![warn(rust_2018_idioms)]
  42 #![cfg_attr(
  43     all(target_env = "sgx", target_vendor = "fortanix"),
  44     feature(sgx_platform)
  45 )]
  46 #![cfg_attr(
  47     all(
  48         feature = "nightly",
  49         target_arch = "wasm32",
  50         target_feature = "atomics"
  51     ),
  52     feature(stdsimd)
  53 )]
  54 #![cfg_attr(
  55     all(feature = "nightly", target_os = "cloudabi",),
  56     feature(thread_local)
  57 )]
  58
  59 mod parking_lot;
  60 mod spinwait;
  61 mod thread_parker;
  62 mod util;
  63 mod word_lock;
  64
  65 pub use self::parking_lot::deadlock;
  66 pub use self::parking_lot::{park, unpark_all, unpark_filter, unpark_one, unpark_requeue};
  67 pub use self::parking_lot::{
  68     FilterOp, ParkResult, ParkToken, RequeueOp, UnparkResult, UnparkToken,
  69 };
  70 pub use self::parking_lot::{DEFAULT_PARK_TOKEN, DEFAULT_UNPARK_TOKEN};
  71 pub use self::spinwait::SpinWait;