fish-shell/fish-rust/src/wait_handle.rs
Johannes Altmanninger bff0caf1d8 common.rs: remove typedefs that have been ported to elsewhere
In general we should keep the existing structure, to minimize surprise.
2023-04-16 17:21:54 +02:00

273 lines
8.0 KiB
Rust

use crate::wchar::WString;
use crate::wchar_ffi::WCharFromFFI;
use cxx::CxxWString;
use libc::pid_t;
use std::cell::Cell;
use std::rc::Rc;
#[cxx::bridge]
mod wait_handle_ffi {
extern "Rust" {
type WaitHandleRefFFI;
fn new_wait_handle_ffi(
pid: i32,
internal_job_id: u64,
base_name: &CxxWString,
) -> Box<WaitHandleRefFFI>;
fn set_status_and_complete(self: &mut WaitHandleRefFFI, status: i32);
type WaitHandleStoreFFI;
fn new_wait_handle_store_ffi() -> Box<WaitHandleStoreFFI>;
fn remove_by_pid(self: &mut WaitHandleStoreFFI, pid: i32);
fn get_job_id_by_pid(self: &WaitHandleStoreFFI, pid: i32) -> u64;
fn try_get_status_and_job_id(
self: &WaitHandleStoreFFI,
pid: i32,
only_if_complete: bool,
status: &mut i32,
job_id: &mut u64,
) -> bool;
fn add(self: &mut WaitHandleStoreFFI, wh: *const Box<WaitHandleRefFFI>);
}
}
pub struct WaitHandleRefFFI(WaitHandleRef);
impl WaitHandleRefFFI {
#[allow(clippy::wrong_self_convention)]
pub fn from_ffi(&self) -> &WaitHandleRef {
&self.0
}
#[allow(clippy::wrong_self_convention)]
pub fn from_ffi_mut(&mut self) -> &mut WaitHandleRef {
&mut self.0
}
fn set_status_and_complete(self: &mut WaitHandleRefFFI, status: i32) {
let wh = self.from_ffi();
assert!(!wh.is_completed(), "wait handle already completed");
wh.status.set(Some(status));
}
}
pub struct WaitHandleStoreFFI(WaitHandleStore);
impl WaitHandleStoreFFI {
#[allow(clippy::wrong_self_convention)]
pub fn from_ffi_mut(&mut self) -> &mut WaitHandleStore {
&mut self.0
}
#[allow(clippy::wrong_self_convention)]
pub fn from_ffi(&self) -> &WaitHandleStore {
&self.0
}
/// \return the job ID for a pid, or 0 if None.
fn get_job_id_by_pid(&self, pid: i32) -> u64 {
self.from_ffi()
.get_by_pid(pid)
.map(|wh| wh.internal_job_id)
.unwrap_or(0)
}
/// Try getting the status and job ID of a job.
/// \return true if the job was found.
/// If only_if_complete is true, then only return true if the job is completed.
fn try_get_status_and_job_id(
self: &WaitHandleStoreFFI,
pid: i32,
only_if_complete: bool,
status: &mut i32,
job_id: &mut u64,
) -> bool {
let whs = self.from_ffi();
let Some(wh) = whs.get_by_pid(pid) else {
return false;
};
if only_if_complete && !wh.is_completed() {
return false;
}
*status = wh.status.get().unwrap_or(0);
*job_id = wh.internal_job_id;
true
}
/// Remove the wait handle for a pid, if present in this store.
fn remove_by_pid(&mut self, pid: i32) {
self.from_ffi_mut().remove_by_pid(pid);
}
fn add(self: &mut WaitHandleStoreFFI, wh: *const Box<WaitHandleRefFFI>) {
if wh.is_null() {
return;
}
let wh = unsafe { (*wh).from_ffi() };
self.from_ffi_mut().add(wh.clone());
}
}
fn new_wait_handle_store_ffi() -> Box<WaitHandleStoreFFI> {
Box::new(WaitHandleStoreFFI(WaitHandleStore::new()))
}
fn new_wait_handle_ffi(
pid: i32,
internal_job_id: u64,
base_name: &CxxWString,
) -> Box<WaitHandleRefFFI> {
Box::new(WaitHandleRefFFI(WaitHandle::new(
pid as pid_t,
internal_job_id,
base_name.from_ffi(),
)))
}
/// The non user-visible, never-recycled job ID.
/// Every job has a unique positive value for this.
pub type InternalJobId = u64;
/// The bits of a job necessary to support 'wait' and '--on-process-exit'.
/// This may outlive the job.
pub struct WaitHandle {
/// The pid of this process.
pub pid: pid_t,
/// The internal job id of the job which contained this process.
pub internal_job_id: InternalJobId,
/// The "base name" of this process.
/// For example if the process is "/bin/sleep" then this will be 'sleep'.
pub base_name: WString,
/// The status, if completed; None if not completed.
status: Cell<Option<i32>>,
}
impl WaitHandle {
/// \return true if this wait handle is completed.
pub fn is_completed(&self) -> bool {
self.status.get().is_some()
}
}
impl WaitHandle {
/// Construct from a pid, job id, and base name.
pub fn new(pid: pid_t, internal_job_id: InternalJobId, base_name: WString) -> WaitHandleRef {
Rc::new(WaitHandle {
pid,
internal_job_id,
base_name,
status: Default::default(),
})
}
}
pub type WaitHandleRef = Rc<WaitHandle>;
const WAIT_HANDLE_STORE_DEFAULT_LIMIT: usize = 1024;
/// Support for storing a list of wait handles, with a max limit set at initialization.
/// Note this class is not safe for concurrent access.
pub struct WaitHandleStore {
// Map from pid to wait handles.
cache: lru::LruCache<pid_t, WaitHandleRef>,
}
impl WaitHandleStore {
/// Construct with the default capacity.
pub fn new() -> WaitHandleStore {
Self::new_with_capacity(WAIT_HANDLE_STORE_DEFAULT_LIMIT)
}
pub fn new_with_capacity(capacity: usize) -> WaitHandleStore {
let capacity = std::num::NonZeroUsize::new(capacity).unwrap();
WaitHandleStore {
cache: lru::LruCache::new(capacity),
}
}
/// Add a wait handle to the store. This may remove the oldest handle, if our limit is exceeded.
/// It may also remove any existing handle with that pid.
pub fn add(&mut self, wh: WaitHandleRef) {
self.cache.put(wh.pid, wh);
}
/// \return the wait handle for a pid, or None if there is none.
/// This is a fast lookup.
pub fn get_by_pid(&self, pid: pid_t) -> Option<WaitHandleRef> {
self.cache.peek(&pid).cloned()
}
/// Remove a given wait handle, if present in this store.
pub fn remove(&mut self, wh: &WaitHandleRef) {
// Note: this differs from remove_by_pid because we verify that the handle is the same.
if let Some(key) = self.cache.peek(&wh.pid) {
if Rc::ptr_eq(key, wh) {
self.cache.pop(&wh.pid);
}
}
}
/// Remove the wait handle for a pid, if present in this store.
pub fn remove_by_pid(&mut self, pid: pid_t) {
self.cache.pop(&pid);
}
/// Iterate over wait handles.
pub fn iter(&self) -> impl Iterator<Item = &WaitHandleRef> {
self.cache.iter().map(|(_, wh)| wh)
}
/// Copy out the list of all wait handles, returning the most-recently-used first.
pub fn get_list(&self) -> Vec<WaitHandleRef> {
self.cache.iter().map(|(_, wh)| wh.clone()).collect()
}
/// Convenience to return the size, for testing.
pub fn size(&self) -> usize {
self.cache.len()
}
}
#[test]
fn test_wait_handles() {
use crate::wchar::L;
let limit: usize = 4;
let mut whs = WaitHandleStore::new_with_capacity(limit);
assert_eq!(whs.size(), 0);
assert!(whs.get_by_pid(5).is_none());
// Duplicate pids drop oldest.
whs.add(WaitHandle::new(5, 0, L!("first").to_owned()));
whs.add(WaitHandle::new(5, 0, L!("second").to_owned()));
assert_eq!(whs.size(), 1);
assert_eq!(whs.get_by_pid(5).unwrap().base_name, "second");
whs.remove_by_pid(123);
assert_eq!(whs.size(), 1);
whs.remove_by_pid(5);
assert_eq!(whs.size(), 0);
// Test evicting oldest.
whs.add(WaitHandle::new(1, 0, L!("1").to_owned()));
whs.add(WaitHandle::new(2, 0, L!("2").to_owned()));
whs.add(WaitHandle::new(3, 0, L!("3").to_owned()));
whs.add(WaitHandle::new(4, 0, L!("4").to_owned()));
whs.add(WaitHandle::new(5, 0, L!("5").to_owned()));
assert_eq!(whs.size(), 4);
let entries = whs.get_list();
let mut iter = entries.iter();
assert_eq!(iter.next().unwrap().base_name, "5");
assert_eq!(iter.next().unwrap().base_name, "4");
assert_eq!(iter.next().unwrap().base_name, "3");
assert_eq!(iter.next().unwrap().base_name, "2");
assert!(iter.next().is_none());
}