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John Doty 2024-03-08 11:03:01 -08:00
parent 5deceec006
commit 977e3c17e5
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91
third-party/vendor/jobserver/src/error.rs vendored Normal file
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#[cfg(unix)]
type RawFd = std::os::unix::io::RawFd;
#[cfg(not(unix))]
type RawFd = std::convert::Infallible;
/// Error type for `from_env_ext` function.
#[derive(Debug)]
pub struct FromEnvError {
pub(crate) inner: FromEnvErrorInner,
}
/// Kind of an error returned from `from_env_ext` function.
#[derive(Debug)]
#[non_exhaustive]
pub enum FromEnvErrorKind {
/// There is no environment variable that describes jobserver to inherit.
NoEnvVar,
/// There is no jobserver in the environment variable.
/// Variables associated with Make can be used for passing data other than jobserver info.
NoJobserver,
/// Cannot parse jobserver environment variable value, incorrect format.
CannotParse,
/// Cannot open path or name from the jobserver environment variable value.
CannotOpenPath,
/// Cannot open file descriptor from the jobserver environment variable value.
CannotOpenFd,
/// The jobserver style is a simple pipe, but at least one of the file descriptors
/// is negative, which means it is disabled for this process
/// ([GNU `make` manual: POSIX Jobserver Interaction](https://www.gnu.org/software/make/manual/make.html#POSIX-Jobserver)).
NegativeFd,
/// File descriptor from the jobserver environment variable value is not a pipe.
NotAPipe,
/// Jobserver inheritance is not supported on this platform.
Unsupported,
}
impl FromEnvError {
/// Get the error kind.
pub fn kind(&self) -> FromEnvErrorKind {
match self.inner {
FromEnvErrorInner::NoEnvVar => FromEnvErrorKind::NoEnvVar,
FromEnvErrorInner::NoJobserver => FromEnvErrorKind::NoJobserver,
FromEnvErrorInner::CannotParse(_) => FromEnvErrorKind::CannotParse,
FromEnvErrorInner::CannotOpenPath(..) => FromEnvErrorKind::CannotOpenPath,
FromEnvErrorInner::CannotOpenFd(..) => FromEnvErrorKind::CannotOpenFd,
FromEnvErrorInner::NegativeFd(..) => FromEnvErrorKind::NegativeFd,
FromEnvErrorInner::NotAPipe(..) => FromEnvErrorKind::NotAPipe,
FromEnvErrorInner::Unsupported => FromEnvErrorKind::Unsupported,
}
}
}
impl std::fmt::Display for FromEnvError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match &self.inner {
FromEnvErrorInner::NoEnvVar => write!(f, "there is no environment variable that describes jobserver to inherit"),
FromEnvErrorInner::NoJobserver => write!(f, "there is no `--jobserver-fds=` or `--jobserver-auth=` in the environment variable"),
FromEnvErrorInner::CannotParse(s) => write!(f, "cannot parse jobserver environment variable value: {s}"),
FromEnvErrorInner::CannotOpenPath(s, err) => write!(f, "cannot open path or name {s} from the jobserver environment variable value: {err}"),
FromEnvErrorInner::CannotOpenFd(fd, err) => write!(f, "cannot open file descriptor {fd} from the jobserver environment variable value: {err}"),
FromEnvErrorInner::NegativeFd(fd) => write!(f, "file descriptor {fd} from the jobserver environment variable value is negative"),
FromEnvErrorInner::NotAPipe(fd, None) => write!(f, "file descriptor {fd} from the jobserver environment variable value is not a pipe"),
FromEnvErrorInner::NotAPipe(fd, Some(err)) => write!(f, "file descriptor {fd} from the jobserver environment variable value is not a pipe: {err}"),
FromEnvErrorInner::Unsupported => write!(f, "jobserver inheritance is not supported on this platform"),
}
}
}
impl std::error::Error for FromEnvError {
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
match &self.inner {
FromEnvErrorInner::CannotOpenPath(_, err) => Some(err),
FromEnvErrorInner::NotAPipe(_, Some(err)) | FromEnvErrorInner::CannotOpenFd(_, err) => {
Some(err)
}
_ => None,
}
}
}
#[allow(dead_code)]
#[derive(Debug)]
pub(crate) enum FromEnvErrorInner {
NoEnvVar,
NoJobserver,
CannotParse(String),
CannotOpenPath(String, std::io::Error),
CannotOpenFd(RawFd, std::io::Error),
NegativeFd(RawFd),
NotAPipe(RawFd, Option<std::io::Error>),
Unsupported,
}

655
third-party/vendor/jobserver/src/lib.rs vendored Normal file
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//! An implementation of the GNU make jobserver.
//!
//! This crate is an implementation, in Rust, of the GNU `make` jobserver for
//! CLI tools that are interoperating with make or otherwise require some form
//! of parallelism limiting across process boundaries. This was originally
//! written for usage in Cargo to both (a) work when `cargo` is invoked from
//! `make` (using `make`'s jobserver) and (b) work when `cargo` invokes build
//! scripts, exporting a jobserver implementation for `make` processes to
//! transitively use.
//!
//! The jobserver implementation can be found in [detail online][docs] but
//! basically boils down to a cross-process semaphore. On Unix this is
//! implemented with the `pipe` syscall and read/write ends of a pipe and on
//! Windows this is implemented literally with IPC semaphores. Starting from
//! GNU `make` version 4.4, named pipe becomes the default way in communication
//! on Unix. This crate also supports that feature in the sense of inheriting
//! and forwarding the correct environment.
//!
//! The jobserver protocol in `make` also dictates when tokens are acquired to
//! run child work, and clients using this crate should take care to implement
//! such details to ensure correct interoperation with `make` itself.
//!
//! ## Examples
//!
//! Connect to a jobserver that was set up by `make` or a different process:
//!
//! ```no_run
//! use jobserver::Client;
//!
//! // See API documentation for why this is `unsafe`
//! let client = match unsafe { Client::from_env() } {
//! Some(client) => client,
//! None => panic!("client not configured"),
//! };
//! ```
//!
//! Acquire and release token from a jobserver:
//!
//! ```no_run
//! use jobserver::Client;
//!
//! let client = unsafe { Client::from_env().unwrap() };
//! let token = client.acquire().unwrap(); // blocks until it is available
//! drop(token); // releases the token when the work is done
//! ```
//!
//! Create a new jobserver and configure a child process to have access:
//!
//! ```
//! use std::process::Command;
//! use jobserver::Client;
//!
//! let client = Client::new(4).expect("failed to create jobserver");
//! let mut cmd = Command::new("make");
//! client.configure(&mut cmd);
//! ```
//!
//! ## Caveats
//!
//! This crate makes no attempt to release tokens back to a jobserver on
//! abnormal exit of a process. If a process which acquires a token is killed
//! with ctrl-c or some similar signal then tokens will not be released and the
//! jobserver may be in a corrupt state.
//!
//! Note that this is typically ok as ctrl-c means that an entire build process
//! is being torn down, but it's worth being aware of at least!
//!
//! ## Windows caveats
//!
//! There appear to be two implementations of `make` on Windows. On MSYS2 one
//! typically comes as `mingw32-make` and the other as `make` itself. I'm not
//! personally too familiar with what's going on here, but for jobserver-related
//! information the `mingw32-make` implementation uses Windows semaphores
//! whereas the `make` program does not. The `make` program appears to use file
//! descriptors and I'm not really sure how it works, so this crate is not
//! compatible with `make` on Windows. It is, however, compatible with
//! `mingw32-make`.
//!
//! [docs]: http://make.mad-scientist.net/papers/jobserver-implementation/
#![deny(missing_docs, missing_debug_implementations)]
#![doc(html_root_url = "https://docs.rs/jobserver/0.1")]
use std::env;
use std::ffi::OsString;
use std::io;
use std::process::Command;
use std::sync::{Arc, Condvar, Mutex, MutexGuard};
mod error;
#[cfg(unix)]
#[path = "unix.rs"]
mod imp;
#[cfg(windows)]
#[path = "windows.rs"]
mod imp;
#[cfg(not(any(unix, windows)))]
#[path = "wasm.rs"]
mod imp;
/// A client of a jobserver
///
/// This structure is the main type exposed by this library, and is where
/// interaction to a jobserver is configured through. Clients are either created
/// from scratch in which case the internal semphore is initialied on the spot,
/// or a client is created from the environment to connect to a jobserver
/// already created.
///
/// Some usage examples can be found in the crate documentation for using a
/// client.
///
/// Note that a `Client` implements the `Clone` trait, and all instances of a
/// `Client` refer to the same jobserver instance.
#[derive(Clone, Debug)]
pub struct Client {
inner: Arc<imp::Client>,
}
/// An acquired token from a jobserver.
///
/// This token will be released back to the jobserver when it is dropped and
/// otherwise represents the ability to spawn off another thread of work.
#[derive(Debug)]
pub struct Acquired {
client: Arc<imp::Client>,
data: imp::Acquired,
disabled: bool,
}
impl Acquired {
/// This drops the `Acquired` token without releasing the associated token.
///
/// This is not generally useful, but can be helpful if you do not have the
/// ability to store an Acquired token but need to not yet release it.
///
/// You'll typically want to follow this up with a call to `release_raw` or
/// similar to actually release the token later on.
pub fn drop_without_releasing(mut self) {
self.disabled = true;
}
}
#[derive(Default, Debug)]
struct HelperState {
lock: Mutex<HelperInner>,
cvar: Condvar,
}
#[derive(Default, Debug)]
struct HelperInner {
requests: usize,
producer_done: bool,
consumer_done: bool,
}
use error::FromEnvErrorInner;
pub use error::{FromEnvError, FromEnvErrorKind};
/// Return type for `from_env_ext` function.
#[derive(Debug)]
pub struct FromEnv {
/// Result of trying to get jobserver client from env.
pub client: Result<Client, FromEnvError>,
/// Name and value of the environment variable.
/// `None` if no relevant environment variable is found.
pub var: Option<(&'static str, OsString)>,
}
impl FromEnv {
fn new_ok(client: Client, var_name: &'static str, var_value: OsString) -> FromEnv {
FromEnv {
client: Ok(client),
var: Some((var_name, var_value)),
}
}
fn new_err(kind: FromEnvErrorInner, var_name: &'static str, var_value: OsString) -> FromEnv {
FromEnv {
client: Err(FromEnvError { inner: kind }),
var: Some((var_name, var_value)),
}
}
}
impl Client {
/// Creates a new jobserver initialized with the given parallelism limit.
///
/// A client to the jobserver created will be returned. This client will
/// allow at most `limit` tokens to be acquired from it in parallel. More
/// calls to `acquire` will cause the calling thread to block.
///
/// Note that the created `Client` is not automatically inherited into
/// spawned child processes from this program. Manual usage of the
/// `configure` function is required for a child process to have access to a
/// job server.
///
/// # Examples
///
/// ```
/// use jobserver::Client;
///
/// let client = Client::new(4).expect("failed to create jobserver");
/// ```
///
/// # Errors
///
/// Returns an error if any I/O error happens when attempting to create the
/// jobserver client.
pub fn new(limit: usize) -> io::Result<Client> {
Ok(Client {
inner: Arc::new(imp::Client::new(limit)?),
})
}
/// Attempts to connect to the jobserver specified in this process's
/// environment.
///
/// When the a `make` executable calls a child process it will configure the
/// environment of the child to ensure that it has handles to the jobserver
/// it's passing down. This function will attempt to look for these details
/// and connect to the jobserver.
///
/// Note that the created `Client` is not automatically inherited into
/// spawned child processes from this program. Manual usage of the
/// `configure` function is required for a child process to have access to a
/// job server.
///
/// # Return value
///
/// `FromEnv` contains result and relevant environment variable.
/// If a jobserver was found in the environment and it looks correct then
/// result with the connected client will be returned. In other cases
/// result will contain `Err(FromEnvErr)`.
///
/// Note that on Unix the `Client` returned **takes ownership of the file
/// descriptors specified in the environment**. Jobservers on Unix are
/// implemented with `pipe` file descriptors, and they're inherited from
/// parent processes. This `Client` returned takes ownership of the file
/// descriptors for this process and will close the file descriptors after
/// this value is dropped.
///
/// Additionally on Unix this function will configure the file descriptors
/// with `CLOEXEC` so they're not automatically inherited by spawned
/// children.
///
/// On unix if `check_pipe` enabled this function will check if provided
/// files are actually pipes.
///
/// # Safety
///
/// This function is `unsafe` to call on Unix specifically as it
/// transitively requires usage of the `from_raw_fd` function, which is
/// itself unsafe in some circumstances.
///
/// It's recommended to call this function very early in the lifetime of a
/// program before any other file descriptors are opened. That way you can
/// make sure to take ownership properly of the file descriptors passed
/// down, if any.
///
/// It's generally unsafe to call this function twice in a program if the
/// previous invocation returned `Some`.
///
/// Note, though, that on Windows it should be safe to call this function
/// any number of times.
pub unsafe fn from_env_ext(check_pipe: bool) -> FromEnv {
let (env, var_os) = match ["CARGO_MAKEFLAGS", "MAKEFLAGS", "MFLAGS"]
.iter()
.map(|&env| env::var_os(env).map(|var| (env, var)))
.find_map(|p| p)
{
Some((env, var_os)) => (env, var_os),
None => return FromEnv::new_err(FromEnvErrorInner::NoEnvVar, "", Default::default()),
};
let var = match var_os.to_str() {
Some(var) => var,
None => {
let err = FromEnvErrorInner::CannotParse("not valid UTF-8".to_string());
return FromEnv::new_err(err, env, var_os);
}
};
let s = match find_jobserver_auth(var) {
Some(s) => s,
None => return FromEnv::new_err(FromEnvErrorInner::NoJobserver, env, var_os),
};
match imp::Client::open(s, check_pipe) {
Ok(c) => FromEnv::new_ok(Client { inner: Arc::new(c) }, env, var_os),
Err(err) => FromEnv::new_err(err, env, var_os),
}
}
/// Attempts to connect to the jobserver specified in this process's
/// environment.
///
/// Wraps `from_env_ext` and discards error details.
pub unsafe fn from_env() -> Option<Client> {
Self::from_env_ext(false).client.ok()
}
/// Acquires a token from this jobserver client.
///
/// This function will block the calling thread until a new token can be
/// acquired from the jobserver.
///
/// # Return value
///
/// On successful acquisition of a token an instance of `Acquired` is
/// returned. This structure, when dropped, will release the token back to
/// the jobserver. It's recommended to avoid leaking this value.
///
/// # Errors
///
/// If an I/O error happens while acquiring a token then this function will
/// return immediately with the error. If an error is returned then a token
/// was not acquired.
pub fn acquire(&self) -> io::Result<Acquired> {
let data = self.inner.acquire()?;
Ok(Acquired {
client: self.inner.clone(),
data,
disabled: false,
})
}
/// Returns amount of tokens in the read-side pipe.
///
/// # Return value
///
/// Number of bytes available to be read from the jobserver pipe
///
/// # Errors
///
/// Underlying errors from the ioctl will be passed up.
pub fn available(&self) -> io::Result<usize> {
self.inner.available()
}
/// Configures a child process to have access to this client's jobserver as
/// well.
///
/// This function is required to be called to ensure that a jobserver is
/// properly inherited to a child process. If this function is *not* called
/// then this `Client` will not be accessible in the child process. In other
/// words, if not called, then `Client::from_env` will return `None` in the
/// child process (or the equivalent of `Child::from_env` that `make` uses).
///
/// ## Platform-specific behavior
///
/// On Unix and Windows this will clobber the `CARGO_MAKEFLAGS` environment
/// variables for the child process, and on Unix this will also allow the
/// two file descriptors for this client to be inherited to the child.
///
/// On platforms other than Unix and Windows this panics.
pub fn configure(&self, cmd: &mut Command) {
cmd.env("CARGO_MAKEFLAGS", &self.mflags_env());
self.inner.configure(cmd);
}
/// Configures a child process to have access to this client's jobserver as
/// well.
///
/// This function is required to be called to ensure that a jobserver is
/// properly inherited to a child process. If this function is *not* called
/// then this `Client` will not be accessible in the child process. In other
/// words, if not called, then `Client::from_env` will return `None` in the
/// child process (or the equivalent of `Child::from_env` that `make` uses).
///
/// ## Platform-specific behavior
///
/// On Unix and Windows this will clobber the `CARGO_MAKEFLAGS`,
/// `MAKEFLAGS` and `MFLAGS` environment variables for the child process,
/// and on Unix this will also allow the two file descriptors for
/// this client to be inherited to the child.
///
/// On platforms other than Unix and Windows this panics.
pub fn configure_make(&self, cmd: &mut Command) {
let value = self.mflags_env();
cmd.env("CARGO_MAKEFLAGS", &value);
cmd.env("MAKEFLAGS", &value);
cmd.env("MFLAGS", &value);
self.inner.configure(cmd);
}
fn mflags_env(&self) -> String {
let arg = self.inner.string_arg();
// Older implementations of make use `--jobserver-fds` and newer
// implementations use `--jobserver-auth`, pass both to try to catch
// both implementations.
format!("-j --jobserver-fds={0} --jobserver-auth={0}", arg)
}
/// Converts this `Client` into a helper thread to deal with a blocking
/// `acquire` function a little more easily.
///
/// The fact that the `acquire` function on `Client` blocks isn't always
/// the easiest to work with. Typically you're using a jobserver to
/// manage running other events in parallel! This means that you need to
/// either (a) wait for an existing job to finish or (b) wait for a
/// new token to become available.
///
/// Unfortunately the blocking in `acquire` happens at the implementation
/// layer of jobservers. On Unix this requires a blocking call to `read`
/// and on Windows this requires one of the `WaitFor*` functions. Both
/// of these situations aren't the easiest to deal with:
///
/// * On Unix there's basically only one way to wake up a `read` early, and
/// that's through a signal. This is what the `make` implementation
/// itself uses, relying on `SIGCHLD` to wake up a blocking acquisition
/// of a new job token. Unfortunately nonblocking I/O is not an option
/// here, so it means that "waiting for one of two events" means that
/// the latter event must generate a signal! This is not always the case
/// on unix for all jobservers.
///
/// * On Windows you'd have to basically use the `WaitForMultipleObjects`
/// which means that you've got to canonicalize all your event sources
/// into a `HANDLE` which also isn't the easiest thing to do
/// unfortunately.
///
/// This function essentially attempts to ease these limitations by
/// converting this `Client` into a helper thread spawned into this
/// process. The application can then request that the helper thread
/// acquires tokens and the provided closure will be invoked for each token
/// acquired.
///
/// The intention is that this function can be used to translate the event
/// of a token acquisition into an arbitrary user-defined event.
///
/// # Arguments
///
/// This function will consume the `Client` provided to be transferred to
/// the helper thread that is spawned. Additionally a closure `f` is
/// provided to be invoked whenever a token is acquired.
///
/// This closure is only invoked after calls to
/// `HelperThread::request_token` have been made and a token itself has
/// been acquired. If an error happens while acquiring the token then
/// an error will be yielded to the closure as well.
///
/// # Return Value
///
/// This function will return an instance of the `HelperThread` structure
/// which is used to manage the helper thread associated with this client.
/// Through the `HelperThread` you'll request that tokens are acquired.
/// When acquired, the closure provided here is invoked.
///
/// When the `HelperThread` structure is returned it will be gracefully
/// torn down, and the calling thread will be blocked until the thread is
/// torn down (which should be prompt).
///
/// # Errors
///
/// This function may fail due to creation of the helper thread or
/// auxiliary I/O objects to manage the helper thread. In any of these
/// situations the error is propagated upwards.
///
/// # Platform-specific behavior
///
/// On Windows this function behaves pretty normally as expected, but on
/// Unix the implementation is... a little heinous. As mentioned above
/// we're forced into blocking I/O for token acquisition, namely a blocking
/// call to `read`. We must be able to unblock this, however, to tear down
/// the helper thread gracefully!
///
/// Essentially what happens is that we'll send a signal to the helper
/// thread spawned and rely on `EINTR` being returned to wake up the helper
/// thread. This involves installing a global `SIGUSR1` handler that does
/// nothing along with sending signals to that thread. This may cause
/// odd behavior in some applications, so it's recommended to review and
/// test thoroughly before using this.
pub fn into_helper_thread<F>(self, f: F) -> io::Result<HelperThread>
where
F: FnMut(io::Result<Acquired>) + Send + 'static,
{
let state = Arc::new(HelperState::default());
Ok(HelperThread {
inner: Some(imp::spawn_helper(self, state.clone(), Box::new(f))?),
state,
})
}
/// Blocks the current thread until a token is acquired.
///
/// This is the same as `acquire`, except that it doesn't return an RAII
/// helper. If successful the process will need to guarantee that
/// `release_raw` is called in the future.
pub fn acquire_raw(&self) -> io::Result<()> {
self.inner.acquire()?;
Ok(())
}
/// Releases a jobserver token back to the original jobserver.
///
/// This is intended to be paired with `acquire_raw` if it was called, but
/// in some situations it could also be called to relinquish a process's
/// implicit token temporarily which is then re-acquired later.
pub fn release_raw(&self) -> io::Result<()> {
self.inner.release(None)?;
Ok(())
}
}
impl Drop for Acquired {
fn drop(&mut self) {
if !self.disabled {
drop(self.client.release(Some(&self.data)));
}
}
}
/// Structure returned from `Client::into_helper_thread` to manage the lifetime
/// of the helper thread returned, see those associated docs for more info.
#[derive(Debug)]
pub struct HelperThread {
inner: Option<imp::Helper>,
state: Arc<HelperState>,
}
impl HelperThread {
/// Request that the helper thread acquires a token, eventually calling the
/// original closure with a token when it's available.
///
/// For more information, see the docs on that function.
pub fn request_token(&self) {
// Indicate that there's one more request for a token and then wake up
// the helper thread if it's sleeping.
self.state.lock().requests += 1;
self.state.cvar.notify_one();
}
}
impl Drop for HelperThread {
fn drop(&mut self) {
// Flag that the producer half is done so the helper thread should exit
// quickly if it's waiting. Wake it up if it's actually waiting
self.state.lock().producer_done = true;
self.state.cvar.notify_one();
// ... and afterwards perform any thread cleanup logic
self.inner.take().unwrap().join();
}
}
impl HelperState {
fn lock(&self) -> MutexGuard<'_, HelperInner> {
self.lock.lock().unwrap_or_else(|e| e.into_inner())
}
/// Executes `f` for each request for a token, where `f` is expected to
/// block and then provide the original closure with a token once it's
/// acquired.
///
/// This is an infinite loop until the helper thread is dropped, at which
/// point everything should get interrupted.
fn for_each_request(&self, mut f: impl FnMut(&HelperState)) {
let mut lock = self.lock();
// We only execute while we could receive requests, but as soon as
// that's `false` we're out of here.
while !lock.producer_done {
// If no one's requested a token then we wait for someone to
// request a token.
if lock.requests == 0 {
lock = self.cvar.wait(lock).unwrap_or_else(|e| e.into_inner());
continue;
}
// Consume the request for a token, and then actually acquire a
// token after unlocking our lock (not that acquisition happens in
// `f`). This ensures that we don't actually hold the lock if we
// wait for a long time for a token.
lock.requests -= 1;
drop(lock);
f(self);
lock = self.lock();
}
lock.consumer_done = true;
self.cvar.notify_one();
}
fn producer_done(&self) -> bool {
self.lock().producer_done
}
}
/// Finds and returns the value of `--jobserver-auth=<VALUE>` in the given
/// environment variable.
///
/// Precedence rules:
///
/// * The last instance wins [^1].
/// * `--jobserver-fds=` as a fallback when no `--jobserver-auth=` is present [^2].
///
/// [^1]: See ["GNU `make` manual: Sharing Job Slots with GNU `make`"](https://www.gnu.org/software/make/manual/make.html#Job-Slots)
/// _"Be aware that the `MAKEFLAGS` variable may contain multiple instances of
/// the `--jobserver-auth=` option. Only the last instance is relevant."_
///
/// [^2]: Refer to [the release announcement](https://git.savannah.gnu.org/cgit/make.git/tree/NEWS?h=4.2#n31)
/// of GNU Make 4.2, which states that `--jobserver-fds` was initially an
/// internal-only flag and was later renamed to `--jobserver-auth`.
fn find_jobserver_auth(var: &str) -> Option<&str> {
["--jobserver-auth=", "--jobserver-fds="]
.iter()
.find_map(|&arg| var.rsplit_once(arg).map(|(_, s)| s))
.and_then(|s| s.split(' ').next())
}
#[test]
fn no_helper_deadlock() {
let x = crate::Client::new(32).unwrap();
let _y = x.clone();
std::mem::drop(x.into_helper_thread(|_| {}).unwrap());
}
#[test]
fn test_find_jobserver_auth() {
let cases = [
("", None),
("-j2", None),
("-j2 --jobserver-auth=3,4", Some("3,4")),
("--jobserver-auth=3,4 -j2", Some("3,4")),
("--jobserver-auth=3,4", Some("3,4")),
("--jobserver-auth=fifo:/myfifo", Some("fifo:/myfifo")),
("--jobserver-auth=", Some("")),
("--jobserver-auth", None),
("--jobserver-fds=3,4", Some("3,4")),
("--jobserver-fds=fifo:/myfifo", Some("fifo:/myfifo")),
("--jobserver-fds=", Some("")),
("--jobserver-fds", None),
(
"--jobserver-auth=auth-a --jobserver-auth=auth-b",
Some("auth-b"),
),
(
"--jobserver-auth=auth-b --jobserver-auth=auth-a",
Some("auth-a"),
),
("--jobserver-fds=fds-a --jobserver-fds=fds-b", Some("fds-b")),
("--jobserver-fds=fds-b --jobserver-fds=fds-a", Some("fds-a")),
(
"--jobserver-auth=auth-a --jobserver-fds=fds-a --jobserver-auth=auth-b",
Some("auth-b"),
),
(
"--jobserver-fds=fds-a --jobserver-auth=auth-a --jobserver-fds=fds-b",
Some("auth-a"),
),
];
for (var, expected) in cases {
let actual = find_jobserver_auth(var);
assert_eq!(
actual, expected,
"expect {expected:?}, got {actual:?}, input `{var:?}`"
);
}
}

486
third-party/vendor/jobserver/src/unix.rs vendored Normal file
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@ -0,0 +1,486 @@
use libc::c_int;
use crate::FromEnvErrorInner;
use std::fs::{File, OpenOptions};
use std::io::{self, Read, Write};
use std::mem;
use std::mem::MaybeUninit;
use std::os::unix::prelude::*;
use std::path::{Path, PathBuf};
use std::process::Command;
use std::ptr;
use std::sync::{Arc, Once};
use std::thread::{self, Builder, JoinHandle};
use std::time::Duration;
#[derive(Debug)]
pub enum Client {
/// `--jobserver-auth=R,W`
Pipe { read: File, write: File },
/// `--jobserver-auth=fifo:PATH`
Fifo { file: File, path: PathBuf },
}
#[derive(Debug)]
pub struct Acquired {
byte: u8,
}
impl Client {
pub fn new(mut limit: usize) -> io::Result<Client> {
let client = unsafe { Client::mk()? };
// I don't think the character written here matters, but I could be
// wrong!
const BUFFER: [u8; 128] = [b'|'; 128];
let mut write = client.write();
set_nonblocking(write.as_raw_fd(), true)?;
while limit > 0 {
let n = limit.min(BUFFER.len());
write.write_all(&BUFFER[..n])?;
limit -= n;
}
set_nonblocking(write.as_raw_fd(), false)?;
Ok(client)
}
unsafe fn mk() -> io::Result<Client> {
let mut pipes = [0; 2];
// Attempt atomically-create-with-cloexec if we can on Linux,
// detected by using the `syscall` function in `libc` to try to work
// with as many kernels/glibc implementations as possible.
#[cfg(target_os = "linux")]
{
use std::sync::atomic::{AtomicBool, Ordering};
static PIPE2_AVAILABLE: AtomicBool = AtomicBool::new(true);
if PIPE2_AVAILABLE.load(Ordering::SeqCst) {
match libc::syscall(libc::SYS_pipe2, pipes.as_mut_ptr(), libc::O_CLOEXEC) {
-1 => {
let err = io::Error::last_os_error();
if err.raw_os_error() == Some(libc::ENOSYS) {
PIPE2_AVAILABLE.store(false, Ordering::SeqCst);
} else {
return Err(err);
}
}
_ => return Ok(Client::from_fds(pipes[0], pipes[1])),
}
}
}
cvt(libc::pipe(pipes.as_mut_ptr()))?;
drop(set_cloexec(pipes[0], true));
drop(set_cloexec(pipes[1], true));
Ok(Client::from_fds(pipes[0], pipes[1]))
}
pub(crate) unsafe fn open(s: &str, check_pipe: bool) -> Result<Client, FromEnvErrorInner> {
if let Some(client) = Self::from_fifo(s)? {
return Ok(client);
}
if let Some(client) = Self::from_pipe(s, check_pipe)? {
return Ok(client);
}
Err(FromEnvErrorInner::CannotParse(format!(
"expected `fifo:PATH` or `R,W`, found `{s}`"
)))
}
/// `--jobserver-auth=fifo:PATH`
fn from_fifo(s: &str) -> Result<Option<Client>, FromEnvErrorInner> {
let mut parts = s.splitn(2, ':');
if parts.next().unwrap() != "fifo" {
return Ok(None);
}
let path_str = parts.next().ok_or_else(|| {
FromEnvErrorInner::CannotParse("expected a path after `fifo:`".to_string())
})?;
let path = Path::new(path_str);
let file = OpenOptions::new()
.read(true)
.write(true)
.open(path)
.map_err(|err| FromEnvErrorInner::CannotOpenPath(path_str.to_string(), err))?;
Ok(Some(Client::Fifo {
file,
path: path.into(),
}))
}
/// `--jobserver-auth=R,W`
unsafe fn from_pipe(s: &str, check_pipe: bool) -> Result<Option<Client>, FromEnvErrorInner> {
let mut parts = s.splitn(2, ',');
let read = parts.next().unwrap();
let write = match parts.next() {
Some(w) => w,
None => return Ok(None),
};
let read = read
.parse()
.map_err(|e| FromEnvErrorInner::CannotParse(format!("cannot parse `read` fd: {e}")))?;
let write = write
.parse()
.map_err(|e| FromEnvErrorInner::CannotParse(format!("cannot parse `write` fd: {e}")))?;
// If either or both of these file descriptors are negative,
// it means the jobserver is disabled for this process.
if read < 0 {
return Err(FromEnvErrorInner::NegativeFd(read));
}
if write < 0 {
return Err(FromEnvErrorInner::NegativeFd(write));
}
// Ok so we've got two integers that look like file descriptors, but
// for extra sanity checking let's see if they actually look like
// valid files and instances of a pipe if feature enabled before we
// return the client.
//
// If we're called from `make` *without* the leading + on our rule
// then we'll have `MAKEFLAGS` env vars but won't actually have
// access to the file descriptors.
//
// `NotAPipe` is a worse error, return it if it's reported for any of the two fds.
match (fd_check(read, check_pipe), fd_check(write, check_pipe)) {
(read_err @ Err(FromEnvErrorInner::NotAPipe(..)), _) => read_err?,
(_, write_err @ Err(FromEnvErrorInner::NotAPipe(..))) => write_err?,
(read_err, write_err) => {
read_err?;
write_err?;
}
}
drop(set_cloexec(read, true));
drop(set_cloexec(write, true));
Ok(Some(Client::from_fds(read, write)))
}
unsafe fn from_fds(read: c_int, write: c_int) -> Client {
Client::Pipe {
read: File::from_raw_fd(read),
write: File::from_raw_fd(write),
}
}
/// Gets the read end of our jobserver client.
fn read(&self) -> &File {
match self {
Client::Pipe { read, .. } => read,
Client::Fifo { file, .. } => file,
}
}
/// Gets the write end of our jobserver client.
fn write(&self) -> &File {
match self {
Client::Pipe { write, .. } => write,
Client::Fifo { file, .. } => file,
}
}
pub fn acquire(&self) -> io::Result<Acquired> {
// Ignore interrupts and keep trying if that happens
loop {
if let Some(token) = self.acquire_allow_interrupts()? {
return Ok(token);
}
}
}
/// Block waiting for a token, returning `None` if we're interrupted with
/// EINTR.
fn acquire_allow_interrupts(&self) -> io::Result<Option<Acquired>> {
// We don't actually know if the file descriptor here is set in
// blocking or nonblocking mode. AFAIK all released versions of
// `make` use blocking fds for the jobserver, but the unreleased
// version of `make` doesn't. In the unreleased version jobserver
// fds are set to nonblocking and combined with `pselect`
// internally.
//
// Here we try to be compatible with both strategies. We optimistically
// try to read from the file descriptor which then may block, return
// a token or indicate that polling is needed.
// Blocking reads (if possible) allows the kernel to be more selective
// about which readers to wake up when a token is written to the pipe.
//
// We use `poll` here to block this thread waiting for read
// readiness, and then afterwards we perform the `read` itself. If
// the `read` returns that it would block then we start over and try
// again.
//
// Also note that we explicitly don't handle EINTR here. That's used
// to shut us down, so we otherwise punt all errors upwards.
unsafe {
let mut fd: libc::pollfd = mem::zeroed();
let mut read = self.read();
fd.fd = read.as_raw_fd();
fd.events = libc::POLLIN;
loop {
let mut buf = [0];
match read.read(&mut buf) {
Ok(1) => return Ok(Some(Acquired { byte: buf[0] })),
Ok(_) => {
return Err(io::Error::new(
io::ErrorKind::Other,
"early EOF on jobserver pipe",
));
}
Err(e) => match e.kind() {
io::ErrorKind::WouldBlock => { /* fall through to polling */ }
io::ErrorKind::Interrupted => return Ok(None),
_ => return Err(e),
},
}
loop {
fd.revents = 0;
if libc::poll(&mut fd, 1, -1) == -1 {
let e = io::Error::last_os_error();
return match e.kind() {
io::ErrorKind::Interrupted => Ok(None),
_ => Err(e),
};
}
if fd.revents != 0 {
break;
}
}
}
}
}
pub fn release(&self, data: Option<&Acquired>) -> io::Result<()> {
// Note that the fd may be nonblocking but we're going to go ahead
// and assume that the writes here are always nonblocking (we can
// always quickly release a token). If that turns out to not be the
// case we'll get an error anyway!
let byte = data.map(|d| d.byte).unwrap_or(b'+');
match self.write().write(&[byte])? {
1 => Ok(()),
_ => Err(io::Error::new(
io::ErrorKind::Other,
"failed to write token back to jobserver",
)),
}
}
pub fn string_arg(&self) -> String {
match self {
Client::Pipe { read, write } => format!("{},{}", read.as_raw_fd(), write.as_raw_fd()),
Client::Fifo { path, .. } => format!("fifo:{}", path.to_str().unwrap()),
}
}
pub fn available(&self) -> io::Result<usize> {
let mut len = MaybeUninit::<c_int>::uninit();
cvt(unsafe { libc::ioctl(self.read().as_raw_fd(), libc::FIONREAD, len.as_mut_ptr()) })?;
Ok(unsafe { len.assume_init() } as usize)
}
pub fn configure(&self, cmd: &mut Command) {
match self {
// We `File::open`ed it when inheriting from environment,
// so no need to set cloexec for fifo.
Client::Fifo { .. } => return,
Client::Pipe { .. } => {}
};
// Here we basically just want to say that in the child process
// we'll configure the read/write file descriptors to *not* be
// cloexec, so they're inherited across the exec and specified as
// integers through `string_arg` above.
let read = self.read().as_raw_fd();
let write = self.write().as_raw_fd();
unsafe {
cmd.pre_exec(move || {
set_cloexec(read, false)?;
set_cloexec(write, false)?;
Ok(())
});
}
}
}
#[derive(Debug)]
pub struct Helper {
thread: JoinHandle<()>,
state: Arc<super::HelperState>,
}
pub(crate) fn spawn_helper(
client: crate::Client,
state: Arc<super::HelperState>,
mut f: Box<dyn FnMut(io::Result<crate::Acquired>) + Send>,
) -> io::Result<Helper> {
static USR1_INIT: Once = Once::new();
let mut err = None;
USR1_INIT.call_once(|| unsafe {
let mut new: libc::sigaction = mem::zeroed();
#[cfg(target_os = "aix")]
{
new.sa_union.__su_sigaction = sigusr1_handler;
}
#[cfg(not(target_os = "aix"))]
{
new.sa_sigaction = sigusr1_handler as usize;
}
new.sa_flags = libc::SA_SIGINFO as _;
if libc::sigaction(libc::SIGUSR1, &new, ptr::null_mut()) != 0 {
err = Some(io::Error::last_os_error());
}
});
if let Some(e) = err.take() {
return Err(e);
}
let state2 = state.clone();
let thread = Builder::new().spawn(move || {
state2.for_each_request(|helper| loop {
match client.inner.acquire_allow_interrupts() {
Ok(Some(data)) => {
break f(Ok(crate::Acquired {
client: client.inner.clone(),
data,
disabled: false,
}));
}
Err(e) => break f(Err(e)),
Ok(None) if helper.producer_done() => break,
Ok(None) => {}
}
});
})?;
Ok(Helper { thread, state })
}
impl Helper {
pub fn join(self) {
let dur = Duration::from_millis(10);
let mut state = self.state.lock();
debug_assert!(state.producer_done);
// We need to join our helper thread, and it could be blocked in one
// of two locations. First is the wait for a request, but the
// initial drop of `HelperState` will take care of that. Otherwise
// it may be blocked in `client.acquire()`. We actually have no way
// of interrupting that, so resort to `pthread_kill` as a fallback.
// This signal should interrupt any blocking `read` call with
// `io::ErrorKind::Interrupt` and cause the thread to cleanly exit.
//
// Note that we don't do this forever though since there's a chance
// of bugs, so only do this opportunistically to make a best effort
// at clearing ourselves up.
for _ in 0..100 {
if state.consumer_done {
break;
}
unsafe {
// Ignore the return value here of `pthread_kill`,
// apparently on OSX if you kill a dead thread it will
// return an error, but on other platforms it may not. In
// that sense we don't actually know if this will succeed or
// not!
libc::pthread_kill(self.thread.as_pthread_t() as _, libc::SIGUSR1);
}
state = self
.state
.cvar
.wait_timeout(state, dur)
.unwrap_or_else(|e| e.into_inner())
.0;
thread::yield_now(); // we really want the other thread to run
}
// If we managed to actually see the consumer get done, then we can
// definitely wait for the thread. Otherwise it's... off in the ether
// I guess?
if state.consumer_done {
drop(self.thread.join());
}
}
}
unsafe fn fcntl_check(fd: c_int) -> Result<(), FromEnvErrorInner> {
match libc::fcntl(fd, libc::F_GETFD) {
-1 => Err(FromEnvErrorInner::CannotOpenFd(
fd,
io::Error::last_os_error(),
)),
_ => Ok(()),
}
}
unsafe fn fd_check(fd: c_int, check_pipe: bool) -> Result<(), FromEnvErrorInner> {
if check_pipe {
let mut stat = mem::zeroed();
if libc::fstat(fd, &mut stat) == -1 {
let last_os_error = io::Error::last_os_error();
fcntl_check(fd)?;
Err(FromEnvErrorInner::NotAPipe(fd, Some(last_os_error)))
} else {
// On android arm and i686 mode_t is u16 and st_mode is u32,
// this generates a type mismatch when S_IFIFO (declared as mode_t)
// is used in operations with st_mode, so we use this workaround
// to get the value of S_IFIFO with the same type of st_mode.
#[allow(unused_assignments)]
let mut s_ififo = stat.st_mode;
s_ififo = libc::S_IFIFO as _;
if stat.st_mode & s_ififo == s_ififo {
return Ok(());
}
Err(FromEnvErrorInner::NotAPipe(fd, None))
}
} else {
fcntl_check(fd)
}
}
fn set_cloexec(fd: c_int, set: bool) -> io::Result<()> {
unsafe {
let previous = cvt(libc::fcntl(fd, libc::F_GETFD))?;
let new = if set {
previous | libc::FD_CLOEXEC
} else {
previous & !libc::FD_CLOEXEC
};
if new != previous {
cvt(libc::fcntl(fd, libc::F_SETFD, new))?;
}
Ok(())
}
}
fn set_nonblocking(fd: c_int, set: bool) -> io::Result<()> {
let status_flag = if set { libc::O_NONBLOCK } else { 0 };
unsafe {
cvt(libc::fcntl(fd, libc::F_SETFL, status_flag))?;
}
Ok(())
}
fn cvt(t: c_int) -> io::Result<c_int> {
if t == -1 {
Err(io::Error::last_os_error())
} else {
Ok(t)
}
}
extern "C" fn sigusr1_handler(
_signum: c_int,
_info: *mut libc::siginfo_t,
_ptr: *mut libc::c_void,
) {
// nothing to do
}

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third-party/vendor/jobserver/src/wasm.rs vendored Normal file
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use crate::FromEnvErrorInner;
use std::io;
use std::process::Command;
use std::sync::{Arc, Condvar, Mutex};
use std::thread::{Builder, JoinHandle};
#[derive(Debug)]
pub struct Client {
inner: Arc<Inner>,
}
#[derive(Debug)]
struct Inner {
count: Mutex<usize>,
cvar: Condvar,
}
#[derive(Debug)]
pub struct Acquired(());
impl Client {
pub fn new(limit: usize) -> io::Result<Client> {
Ok(Client {
inner: Arc::new(Inner {
count: Mutex::new(limit),
cvar: Condvar::new(),
}),
})
}
pub(crate) unsafe fn open(_s: &str, _check_pipe: bool) -> Result<Client, FromEnvErrorInner> {
Err(FromEnvErrorInner::Unsupported)
}
pub fn acquire(&self) -> io::Result<Acquired> {
let mut lock = self.inner.count.lock().unwrap_or_else(|e| e.into_inner());
while *lock == 0 {
lock = self
.inner
.cvar
.wait(lock)
.unwrap_or_else(|e| e.into_inner());
}
*lock -= 1;
Ok(Acquired(()))
}
pub fn release(&self, _data: Option<&Acquired>) -> io::Result<()> {
let mut lock = self.inner.count.lock().unwrap_or_else(|e| e.into_inner());
*lock += 1;
drop(lock);
self.inner.cvar.notify_one();
Ok(())
}
pub fn string_arg(&self) -> String {
panic!(
"On this platform there is no cross process jobserver support,
so Client::configure is not supported."
);
}
pub fn available(&self) -> io::Result<usize> {
let lock = self.inner.count.lock().unwrap_or_else(|e| e.into_inner());
Ok(*lock)
}
pub fn configure(&self, _cmd: &mut Command) {
unreachable!();
}
}
#[derive(Debug)]
pub struct Helper {
thread: JoinHandle<()>,
}
pub(crate) fn spawn_helper(
client: crate::Client,
state: Arc<super::HelperState>,
mut f: Box<dyn FnMut(io::Result<crate::Acquired>) + Send>,
) -> io::Result<Helper> {
let thread = Builder::new().spawn(move || {
state.for_each_request(|_| f(client.acquire()));
})?;
Ok(Helper { thread: thread })
}
impl Helper {
pub fn join(self) {
// TODO: this is not correct if the thread is blocked in
// `client.acquire()`.
drop(self.thread.join());
}
}

270
third-party/vendor/jobserver/src/windows.rs vendored Normal file
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use crate::FromEnvErrorInner;
use std::ffi::CString;
use std::io;
use std::process::Command;
use std::ptr;
use std::sync::Arc;
use std::thread::{Builder, JoinHandle};
#[derive(Debug)]
pub struct Client {
sem: Handle,
name: String,
}
#[derive(Debug)]
pub struct Acquired;
type BOOL = i32;
type DWORD = u32;
type HANDLE = *mut u8;
type LONG = i32;
const ERROR_ALREADY_EXISTS: DWORD = 183;
const FALSE: BOOL = 0;
const INFINITE: DWORD = 0xffffffff;
const SEMAPHORE_MODIFY_STATE: DWORD = 0x2;
const SYNCHRONIZE: DWORD = 0x00100000;
const TRUE: BOOL = 1;
const WAIT_OBJECT_0: DWORD = 0;
extern "system" {
fn CloseHandle(handle: HANDLE) -> BOOL;
fn SetEvent(hEvent: HANDLE) -> BOOL;
fn WaitForMultipleObjects(
ncount: DWORD,
lpHandles: *const HANDLE,
bWaitAll: BOOL,
dwMilliseconds: DWORD,
) -> DWORD;
fn CreateEventA(
lpEventAttributes: *mut u8,
bManualReset: BOOL,
bInitialState: BOOL,
lpName: *const i8,
) -> HANDLE;
fn ReleaseSemaphore(
hSemaphore: HANDLE,
lReleaseCount: LONG,
lpPreviousCount: *mut LONG,
) -> BOOL;
fn CreateSemaphoreA(
lpEventAttributes: *mut u8,
lInitialCount: LONG,
lMaximumCount: LONG,
lpName: *const i8,
) -> HANDLE;
fn OpenSemaphoreA(dwDesiredAccess: DWORD, bInheritHandle: BOOL, lpName: *const i8) -> HANDLE;
fn WaitForSingleObject(hHandle: HANDLE, dwMilliseconds: DWORD) -> DWORD;
#[link_name = "SystemFunction036"]
fn RtlGenRandom(RandomBuffer: *mut u8, RandomBufferLength: u32) -> u8;
}
// Note that we ideally would use the `getrandom` crate, but unfortunately
// that causes build issues when this crate is used in rust-lang/rust (see
// rust-lang/rust#65014 for more information). As a result we just inline
// the pretty simple Windows-specific implementation of generating
// randomness.
fn getrandom(dest: &mut [u8]) -> io::Result<()> {
// Prevent overflow of u32
for chunk in dest.chunks_mut(u32::max_value() as usize) {
let ret = unsafe { RtlGenRandom(chunk.as_mut_ptr(), chunk.len() as u32) };
if ret == 0 {
return Err(io::Error::new(
io::ErrorKind::Other,
"failed to generate random bytes",
));
}
}
Ok(())
}
impl Client {
pub fn new(limit: usize) -> io::Result<Client> {
// Try a bunch of random semaphore names until we get a unique one,
// but don't try for too long.
//
// Note that `limit == 0` is a valid argument above but Windows
// won't let us create a semaphore with 0 slots available to it. Get
// `limit == 0` working by creating a semaphore instead with one
// slot and then immediately acquire it (without ever releaseing it
// back).
for _ in 0..100 {
let mut bytes = [0; 4];
getrandom(&mut bytes)?;
let mut name = format!("__rust_jobserver_semaphore_{}\0", u32::from_ne_bytes(bytes));
unsafe {
let create_limit = if limit == 0 { 1 } else { limit };
let r = CreateSemaphoreA(
ptr::null_mut(),
create_limit as LONG,
create_limit as LONG,
name.as_ptr() as *const _,
);
if r.is_null() {
return Err(io::Error::last_os_error());
}
let handle = Handle(r);
let err = io::Error::last_os_error();
if err.raw_os_error() == Some(ERROR_ALREADY_EXISTS as i32) {
continue;
}
name.pop(); // chop off the trailing nul
let client = Client {
sem: handle,
name: name,
};
if create_limit != limit {
client.acquire()?;
}
return Ok(client);
}
}
Err(io::Error::new(
io::ErrorKind::Other,
"failed to find a unique name for a semaphore",
))
}
pub(crate) unsafe fn open(s: &str, _check_pipe: bool) -> Result<Client, FromEnvErrorInner> {
let name = match CString::new(s) {
Ok(s) => s,
Err(e) => return Err(FromEnvErrorInner::CannotParse(e.to_string())),
};
let sem = OpenSemaphoreA(SYNCHRONIZE | SEMAPHORE_MODIFY_STATE, FALSE, name.as_ptr());
if sem.is_null() {
Err(FromEnvErrorInner::CannotOpenPath(
s.to_string(),
io::Error::last_os_error(),
))
} else {
Ok(Client {
sem: Handle(sem),
name: s.to_string(),
})
}
}
pub fn acquire(&self) -> io::Result<Acquired> {
unsafe {
let r = WaitForSingleObject(self.sem.0, INFINITE);
if r == WAIT_OBJECT_0 {
Ok(Acquired)
} else {
Err(io::Error::last_os_error())
}
}
}
pub fn release(&self, _data: Option<&Acquired>) -> io::Result<()> {
unsafe {
let r = ReleaseSemaphore(self.sem.0, 1, ptr::null_mut());
if r != 0 {
Ok(())
} else {
Err(io::Error::last_os_error())
}
}
}
pub fn string_arg(&self) -> String {
self.name.clone()
}
pub fn available(&self) -> io::Result<usize> {
// Can't read value of a semaphore on Windows, so
// try to acquire without sleeping, since we can find out the
// old value on release. If acquisiton fails, then available is 0.
unsafe {
let r = WaitForSingleObject(self.sem.0, 0);
if r != WAIT_OBJECT_0 {
Ok(0)
} else {
let mut prev: LONG = 0;
let r = ReleaseSemaphore(self.sem.0, 1, &mut prev);
if r != 0 {
Ok(prev as usize + 1)
} else {
Err(io::Error::last_os_error())
}
}
}
}
pub fn configure(&self, _cmd: &mut Command) {
// nothing to do here, we gave the name of our semaphore to the
// child above
}
}
#[derive(Debug)]
struct Handle(HANDLE);
// HANDLE is a raw ptr, but we're send/sync
unsafe impl Sync for Handle {}
unsafe impl Send for Handle {}
impl Drop for Handle {
fn drop(&mut self) {
unsafe {
CloseHandle(self.0);
}
}
}
#[derive(Debug)]
pub struct Helper {
event: Arc<Handle>,
thread: JoinHandle<()>,
}
pub(crate) fn spawn_helper(
client: crate::Client,
state: Arc<super::HelperState>,
mut f: Box<dyn FnMut(io::Result<crate::Acquired>) + Send>,
) -> io::Result<Helper> {
let event = unsafe {
let r = CreateEventA(ptr::null_mut(), TRUE, FALSE, ptr::null());
if r.is_null() {
return Err(io::Error::last_os_error());
} else {
Handle(r)
}
};
let event = Arc::new(event);
let event2 = event.clone();
let thread = Builder::new().spawn(move || {
let objects = [event2.0, client.inner.sem.0];
state.for_each_request(|_| {
const WAIT_OBJECT_1: u32 = WAIT_OBJECT_0 + 1;
match unsafe { WaitForMultipleObjects(2, objects.as_ptr(), FALSE, INFINITE) } {
WAIT_OBJECT_0 => return,
WAIT_OBJECT_1 => f(Ok(crate::Acquired {
client: client.inner.clone(),
data: Acquired,
disabled: false,
})),
_ => f(Err(io::Error::last_os_error())),
}
});
})?;
Ok(Helper { thread, event })
}
impl Helper {
pub fn join(self) {
// Unlike unix this logic is much easier. If our thread was blocked
// in waiting for requests it should already be woken up and
// exiting. Otherwise it's waiting for a token, so we wake it up
// with a different event that it's also waiting on here. After
// these two we should be guaranteed the thread is on its way out,
// so we can safely `join`.
let r = unsafe { SetEvent(self.event.0) };
if r == 0 {
panic!("failed to set event: {}", io::Error::last_os_error());
}
drop(self.thread.join());
}
}