core: sausage-vfs per process (/, /proc, /self, /run), activation, graph, watcher, upgrades
- /proc is a core layer: core/ (PROTOCOL.md, graph.json, graph.dot, locks.json, plugins/<name>/discover.json and client.rs) and one folder per process (info.json, log, and its /self files). - Locks are released only after the task ended, the store dropped, and in-flight file operations returned. - core.activate and core.revert with copies, discovery, compatibility checks of imports and consumers, groups, force. An admission gate makes the snapshot of old processes complete. - Graph of discover documents by hash, refreshed by a file watcher. - Upgrades: grace periods (x-sausage-grace), stop, service restarts, rpc.retired. - SDK plugins in the real core (cli/tests/sdk.rs).
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//! Grace periods, service restarts, and retirement of replaced versions (PROTOCOL.md section 3.7).
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use crate::{Host, services::Service};
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use serde_json::json;
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use std::{collections::BTreeMap, time::Duration};
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use tokio::sync::watch;
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pub(crate) struct OldProcess {
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pid: String,
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version: String,
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ended: watch::Receiver<bool>,
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}
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pub(crate) struct Upgrade {
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plugin: String,
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previous: String,
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grace: Duration,
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processes: Vec<OldProcess>,
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services: Vec<(Service, Option<watch::Receiver<bool>>)>,
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}
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impl Host {
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/// Snapshots old admissions while activation holds the admission write guard.
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pub(crate) fn snapshot_upgrade(
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&self,
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plugin: &str,
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previous: String,
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current: &str,
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grace: f64,
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) -> Upgrade {
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let mut state = self.0.state.lock().unwrap();
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let processes = state
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.processes
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.iter()
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.filter(|(_, process)| process.info.plugin == plugin && process.info.version != current)
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.map(|(pid, process)| OldProcess {
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pid: pid.clone(),
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version: process.info.version.clone(),
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ended: process.ended.subscribe(),
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})
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.collect();
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let mut services = Vec::new();
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let mut retained = Vec::new();
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for service in std::mem::take(&mut state.services) {
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if service
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.method
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.split_once('.')
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.is_some_and(|(name, _)| name == plugin)
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{
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let ended = state
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.processes
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.values()
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.find(|process| process.id.as_ref() == Some(&service.request))
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.map(|process| process.ended.subscribe());
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services.push((service, ended));
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} else {
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retained.push(service);
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}
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}
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state.services = retained;
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Upgrade {
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plugin: plugin.into(),
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previous,
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grace: Duration::from_secs_f64(grace),
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processes,
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services,
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}
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}
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/// Lets old calls finish, stops them after grace, and starts each lifecycle hook once.
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pub(crate) fn begin_upgrade(&self, upgrade: Upgrade) {
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let host = self.clone();
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tokio::spawn(async move {
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host.0.journal.write(
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"core",
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&upgrade.plugin,
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"core",
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&format!("upgrade grace {} seconds", upgrade.grace.as_secs_f64()),
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);
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let mut versions: BTreeMap<String, Vec<watch::Receiver<bool>>> = BTreeMap::new();
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versions.entry(upgrade.previous).or_default();
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for process in upgrade.processes {
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versions
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.entry(process.version)
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.or_default()
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.push(process.ended.clone());
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let host = host.clone();
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let grace = upgrade.grace;
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tokio::spawn(async move {
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let mut ended = process.ended;
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tokio::select! {
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_ = ended.wait_for(|ended|*ended) => (),
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_ = tokio::time::sleep(grace) => { host.begin_stop(&process.pid); }
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}
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});
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}
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for (service, ended) in upgrade.services {
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let host = host.clone();
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tokio::spawn(async move {
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if let Some(mut ended) = ended {
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let _ = ended.wait_for(|ended| *ended).await;
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}
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host.start_service(service.method, service.params).await;
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});
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}
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for (version, processes) in versions {
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let host = host.clone();
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let plugin = upgrade.plugin.clone();
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let retirement = (plugin.clone(), version.clone());
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if !host
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.0
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.retirements
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.lock()
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.unwrap()
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.insert(retirement.clone())
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{
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continue;
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}
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tokio::spawn(async move {
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for mut ended in processes {
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let _ = ended.wait_for(|ended| *ended).await;
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}
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if host
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.0
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.graph
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.lock()
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.unwrap()
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.plugins
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.get(&plugin)
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.is_some_and(|current| current.hash == version)
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{
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host.0.retirements.lock().unwrap().remove(&retirement);
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return;
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}
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host.0.journal.write(
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"core",
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&plugin,
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"core",
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&format!("retired start {version}"),
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);
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let result = host
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.route(
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"core".into(),
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Some(json!(uuid::Uuid::now_v7().to_string())),
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format!("{plugin}.rpc.retired"),
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json!({"previous":version}),
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true,
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)
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.await;
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host.0.journal.write(
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"core",
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&plugin,
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"core",
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&format!("retired result {result:?}"),
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);
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host.0.retirements.lock().unwrap().remove(&retirement);
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});
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}
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});
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}
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}
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