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| 1 | +// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT |
| 2 | +// file at the top-level directory of this distribution and at |
| 3 | +// http://rust-lang.org/COPYRIGHT. |
| 4 | +// |
| 5 | +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| 6 | +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| 7 | +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| 8 | +// option. This file may not be copied, modified, or distributed |
| 9 | +// except according to those terms. |
| 10 | + |
| 11 | +//! Implementation of the helper thread for the timer module |
| 12 | +//! |
| 13 | +//! This module contains the management necessary for the timer worker thread. |
| 14 | +//! This thread is responsible for performing the send()s on channels for timers |
| 15 | +//! that are using channels instead of a blocking call. |
| 16 | +//! |
| 17 | +//! The timer thread is lazily initialized, and it's shut down via the |
| 18 | +//! `shutdown` function provided. It must be maintained as an invariant that |
| 19 | +//! `shutdown` is only called when the entire program is finished. No new timers |
| 20 | +//! can be created in the future and there must be no active timers at that |
| 21 | +//! time. |
| 22 | +
|
| 23 | +use std::mem; |
| 24 | +use std::rt::bookkeeping; |
| 25 | +use std::rt; |
| 26 | +use std::rt::mutex::{StaticNativeMutex, NATIVE_MUTEX_INIT}; |
| 27 | + |
| 28 | +use io::timer::{Req, Shutdown}; |
| 29 | +use task; |
| 30 | + |
| 31 | +// You'll note that these variables are *not* protected by a lock. These |
| 32 | +// variables are initialized with a Once before any Timer is created and are |
| 33 | +// only torn down after everything else has exited. This means that these |
| 34 | +// variables are read-only during use (after initialization) and both of which |
| 35 | +// are safe to use concurrently. |
| 36 | +static mut HELPER_CHAN: *mut Sender<Req> = 0 as *mut Sender<Req>; |
| 37 | +static mut HELPER_SIGNAL: imp::signal = 0 as imp::signal; |
| 38 | + |
| 39 | +static mut TIMER_HELPER_EXIT: StaticNativeMutex = NATIVE_MUTEX_INIT; |
| 40 | + |
| 41 | +pub fn boot(helper: fn(imp::signal, Receiver<Req>)) { |
| 42 | + static mut LOCK: StaticNativeMutex = NATIVE_MUTEX_INIT; |
| 43 | + static mut INITIALIZED: bool = false; |
| 44 | + |
| 45 | + unsafe { |
| 46 | + let mut _guard = LOCK.lock(); |
| 47 | + if !INITIALIZED { |
| 48 | + let (tx, rx) = channel(); |
| 49 | + // promote this to a shared channel |
| 50 | + drop(tx.clone()); |
| 51 | + HELPER_CHAN = mem::transmute(box tx); |
| 52 | + let (receive, send) = imp::new(); |
| 53 | + HELPER_SIGNAL = send; |
| 54 | + |
| 55 | + task::spawn(proc() { |
| 56 | + bookkeeping::decrement(); |
| 57 | + helper(receive, rx); |
| 58 | + TIMER_HELPER_EXIT.lock().signal() |
| 59 | + }); |
| 60 | + |
| 61 | + rt::at_exit(proc() { shutdown() }); |
| 62 | + INITIALIZED = true; |
| 63 | + } |
| 64 | + } |
| 65 | +} |
| 66 | + |
| 67 | +pub fn send(req: Req) { |
| 68 | + unsafe { |
| 69 | + assert!(!HELPER_CHAN.is_null()); |
| 70 | + (*HELPER_CHAN).send(req); |
| 71 | + imp::signal(HELPER_SIGNAL); |
| 72 | + } |
| 73 | +} |
| 74 | + |
| 75 | +fn shutdown() { |
| 76 | + // Request a shutdown, and then wait for the task to exit |
| 77 | + unsafe { |
| 78 | + let guard = TIMER_HELPER_EXIT.lock(); |
| 79 | + send(Shutdown); |
| 80 | + guard.wait(); |
| 81 | + drop(guard); |
| 82 | + TIMER_HELPER_EXIT.destroy(); |
| 83 | + } |
| 84 | + |
| 85 | + |
| 86 | + // Clean up after ther helper thread |
| 87 | + unsafe { |
| 88 | + imp::close(HELPER_SIGNAL); |
| 89 | + let _chan: Box<Sender<Req>> = mem::transmute(HELPER_CHAN); |
| 90 | + HELPER_CHAN = 0 as *mut Sender<Req>; |
| 91 | + HELPER_SIGNAL = 0 as imp::signal; |
| 92 | + } |
| 93 | +} |
| 94 | + |
| 95 | +#[cfg(unix)] |
| 96 | +mod imp { |
| 97 | + use libc; |
| 98 | + use std::os; |
| 99 | + |
| 100 | + use io::file::FileDesc; |
| 101 | + |
| 102 | + pub type signal = libc::c_int; |
| 103 | + |
| 104 | + pub fn new() -> (signal, signal) { |
| 105 | + let pipe = os::pipe(); |
| 106 | + (pipe.input, pipe.out) |
| 107 | + } |
| 108 | + |
| 109 | + pub fn signal(fd: libc::c_int) { |
| 110 | + FileDesc::new(fd, false).inner_write([0]).unwrap(); |
| 111 | + } |
| 112 | + |
| 113 | + pub fn close(fd: libc::c_int) { |
| 114 | + let _fd = FileDesc::new(fd, true); |
| 115 | + } |
| 116 | +} |
| 117 | + |
| 118 | +#[cfg(windows)] |
| 119 | +mod imp { |
| 120 | + use libc::{BOOL, LPCSTR, HANDLE, LPSECURITY_ATTRIBUTES, CloseHandle}; |
| 121 | + use std::ptr; |
| 122 | + use libc; |
| 123 | + |
| 124 | + pub type signal = HANDLE; |
| 125 | + |
| 126 | + pub fn new() -> (HANDLE, HANDLE) { |
| 127 | + unsafe { |
| 128 | + let handle = CreateEventA(ptr::mut_null(), libc::FALSE, libc::FALSE, |
| 129 | + ptr::null()); |
| 130 | + (handle, handle) |
| 131 | + } |
| 132 | + } |
| 133 | + |
| 134 | + pub fn signal(handle: HANDLE) { |
| 135 | + assert!(unsafe { SetEvent(handle) != 0 }); |
| 136 | + } |
| 137 | + |
| 138 | + pub fn close(handle: HANDLE) { |
| 139 | + assert!(unsafe { CloseHandle(handle) != 0 }); |
| 140 | + } |
| 141 | + |
| 142 | + extern "system" { |
| 143 | + fn CreateEventA(lpSecurityAttributes: LPSECURITY_ATTRIBUTES, |
| 144 | + bManualReset: BOOL, |
| 145 | + bInitialState: BOOL, |
| 146 | + lpName: LPCSTR) -> HANDLE; |
| 147 | + fn SetEvent(hEvent: HANDLE) -> BOOL; |
| 148 | + } |
| 149 | +} |
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