112 lines
3.4 KiB
Rust
112 lines
3.4 KiB
Rust
//! Adapts VFS observation to bounded, pollable world-path change queues.
|
|
use super::{
|
|
State,
|
|
bindings::sausage::process::host::{Change, ChangeKind, HostWatcher},
|
|
};
|
|
use sausage_vfs::observe::{ChangeKind as Kind, under};
|
|
use tokio::sync::broadcast::{Receiver, error::TryRecvError};
|
|
use wasmtime::component::Resource;
|
|
use wasmtime_wasi::p2::{DynPollable, Pollable, subscribe};
|
|
|
|
pub struct Watcher {
|
|
paths: Vec<String>,
|
|
events: Receiver<(String, Kind)>,
|
|
pending: Vec<Change>,
|
|
}
|
|
impl Watcher {
|
|
fn push(&mut self, path: String, kind: Kind) {
|
|
if self.paths.iter().any(|base| under(&path, base)) {
|
|
if self
|
|
.pending
|
|
.iter()
|
|
.any(|c| matches!(c.kind, ChangeKind::Overflow))
|
|
{
|
|
return;
|
|
}
|
|
if self.pending.len() >= 256 {
|
|
self.overflow();
|
|
return;
|
|
}
|
|
self.pending.push(Change {
|
|
path,
|
|
kind: match kind {
|
|
Kind::Created => ChangeKind::Created,
|
|
Kind::Modified => ChangeKind::Modified,
|
|
Kind::Removed => ChangeKind::Removed,
|
|
},
|
|
});
|
|
}
|
|
}
|
|
fn overflow(&mut self) {
|
|
self.pending.clear();
|
|
self.pending.push(Change {
|
|
path: "/".into(),
|
|
kind: ChangeKind::Overflow,
|
|
});
|
|
}
|
|
fn drain(&mut self) {
|
|
loop {
|
|
match self.events.try_recv() {
|
|
Ok((path, kind)) => self.push(path, kind),
|
|
Err(TryRecvError::Lagged(_)) => self.overflow(),
|
|
Err(_) => break,
|
|
}
|
|
}
|
|
}
|
|
}
|
|
#[async_trait::async_trait]
|
|
impl Pollable for Watcher {
|
|
async fn ready(&mut self) {
|
|
loop {
|
|
self.drain();
|
|
if !self.pending.is_empty() {
|
|
return;
|
|
}
|
|
match self.events.recv().await {
|
|
Ok((path, kind)) => self.push(path, kind),
|
|
Err(tokio::sync::broadcast::error::RecvError::Lagged(_)) => self.overflow(),
|
|
Err(_) => return,
|
|
}
|
|
}
|
|
}
|
|
}
|
|
impl HostWatcher for State {
|
|
async fn new(&mut self, paths: Vec<String>) -> wasmtime::Result<Resource<Watcher>> {
|
|
let observer = self
|
|
.runtime
|
|
.world
|
|
.root
|
|
.observer()
|
|
.ok_or_else(|| wasmtime::format_err!("filesystem has no observer"))?;
|
|
let paths: Vec<String> = paths
|
|
.iter()
|
|
.map(|p| {
|
|
sausage_vfs::resolve("/", p)
|
|
.trim_end_matches('/')
|
|
.to_owned()
|
|
})
|
|
.map(|p| if p.is_empty() { "/".into() } else { p })
|
|
.collect();
|
|
Ok(self.table.push(Watcher {
|
|
events: observer.subscribe(paths.clone()),
|
|
paths,
|
|
pending: Vec::new(),
|
|
})?)
|
|
}
|
|
async fn subscribe(
|
|
&mut self,
|
|
watcher: Resource<Watcher>,
|
|
) -> wasmtime::Result<Resource<DynPollable>> {
|
|
subscribe(&mut self.table, watcher)
|
|
}
|
|
async fn changes(&mut self, watcher: Resource<Watcher>) -> wasmtime::Result<Vec<Change>> {
|
|
let watcher = self.table.get_mut(&watcher)?;
|
|
watcher.drain();
|
|
Ok(std::mem::take(&mut watcher.pending))
|
|
}
|
|
async fn drop(&mut self, watcher: Resource<Watcher>) -> wasmtime::Result<()> {
|
|
self.table.delete(watcher)?;
|
|
Ok(())
|
|
}
|
|
}
|