feat(call): implement abort cascade for nested calls (ADR-016) (task: call/protocol/abort-cascade)

- PendingEntry stores parent_request_id (Call and Subscribe) and started flag
  for abort-cascade tree indexing
- register_call/register_subscribe accept optional parent_request_id
- AbortCascade::cascade_abort walks the call tree by parent_request_id and
  aborts descendants per AbortPolicy (AbortDependents: all; ContinueRunning:
  unstarted only). Returns sorted list of aborted request IDs
- call.aborted for unknown request_id silently discarded (empty result)
- Composed child request_ids stay internal (not sent as call.requested)
- mark_started() tracks dispatch state for ContinueRunning decisions
- 20 unit tests covering AbortDependents/ContinueRunning, depth-3 tree,
  unknown root, mixed Call/Subscribe, determinism
This commit is contained in:
2026-06-23 15:49:07 +00:00
parent bea19de3cf
commit 3317bc8d1a
4 changed files with 498 additions and 18 deletions

View File

@@ -1,7 +1,393 @@
//! Abort cascade logic for nested calls (ADR-016).
//!
//! When `call.aborted` arrives for a parent request, the protocol cascades
//! the abort to all non-terminal descendants in the call tree. Default
//! policy is `abort-dependents`; `continue-running` is an opt-in.
//! the abort to all non-terminal descendants in the call tree. The default
//! policy is `abort-dependents`; `continue-running` is an opt-in for
//! long-running work that should survive a parent's abort.
//!
//! The call tree is indexed by `parent_request_id` in the
//! `PendingRequestMap`. The root request has `parent_request_id: None`;
//! each composed call has `parent_request_id: Some(parent.request_id)`.
//! Composed child request IDs are internal — they appear in the map for
//! abort-cascade indexing but are not sent as `call.requested` to any
//! peer. The client only sees `call.aborted` for the root ID it sent; the
//! server cascades internally to descendants.
// TODO: implement
use super::pending::PendingRequestMap;
use crate::registry::context::AbortPolicy;
pub struct AbortCascade<'a> {
pending: &'a mut PendingRequestMap,
}
impl<'a> AbortCascade<'a> {
pub fn new(pending: &'a mut PendingRequestMap) -> Self {
Self { pending }
}
/// Cascade an abort from the given request ID to all non-terminal
/// descendants in the call tree. Returns the list of descendant
/// request IDs that were aborted (for logging/auditing), sorted for
/// determinism. The root request itself is not touched by this
/// method — the caller is responsible for aborting the root (the
/// trigger of the cascade).
///
/// Under `AbortDependents` (default): all descendants are aborted,
/// regardless of whether they have started.
///
/// Under `ContinueRunning`: only descendants that have not started
/// are aborted; started descendants continue to completion. No new
/// descendants start (the parent is gone). This is the conservative
/// approximation noted in ADR-016: a descendant is "started" if
/// `PendingEntry::started` is true (the handler has begun
/// executing). A `call.aborted` for an unknown request ID is
/// silently discarded — `cascade_abort` on an unknown root returns
/// an empty list and removes nothing.
pub fn cascade_abort(&mut self, root_request_id: &str, policy: AbortPolicy) -> Vec<String> {
if !self.pending.contains(root_request_id) {
return Vec::new();
}
let descendants = self.find_descendants(root_request_id);
let mut aborted = Vec::new();
match policy {
AbortPolicy::AbortDependents => {
for id in &descendants {
if self.pending.handle_aborted(id) {
aborted.push(id.clone());
}
}
}
AbortPolicy::ContinueRunning => {
for id in &descendants {
let started = self.pending.is_started(id).unwrap_or(false);
if !started && self.pending.handle_aborted(id) {
aborted.push(id.clone());
}
}
}
}
aborted.sort();
aborted
}
/// Find all descendants of a request ID in the call tree by walking
/// the `parent_request_id` index. Returns descendants in
/// breadth-first order with each level's children sorted for
/// determinism. The root itself is not included in the result.
fn find_descendants(&self, parent_id: &str) -> Vec<String> {
let mut descendants = Vec::new();
let mut frontier: Vec<String> = vec![parent_id.to_string()];
while let Some(current) = frontier.pop() {
let mut children: Vec<String> = self
.pending
.request_ids()
.into_iter()
.filter(|id| {
self.pending
.parent_of(id)
.flatten()
.is_some_and(|p| p == current)
})
.collect();
children.sort();
for child in children {
descendants.push(child.clone());
frontier.push(child);
}
}
descendants
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::protocol::wire::CallError;
use std::time::{Duration, Instant};
fn register_call(map: &mut PendingRequestMap, id: &str, parent: Option<&str>) {
map.register_call(
id.to_string(),
Instant::now() + Duration::from_secs(30),
parent.map(|p| p.to_string()),
);
}
fn register_subscribe(map: &mut PendingRequestMap, id: &str, parent: Option<&str>) {
map.register_subscribe(id.to_string(), None, parent.map(|p| p.to_string()));
}
#[test]
fn cascade_abort_unknown_root_returns_empty_and_is_noop() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("does-not-exist", AbortPolicy::AbortDependents);
assert!(aborted.is_empty());
assert!(cascade.pending.contains("r1"));
}
#[test]
fn cascade_abort_abort_dependents_aborts_all_descendants() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
register_call(&mut map, "r1-a", Some("r1"));
register_call(&mut map, "r1-b", Some("r1"));
register_call(&mut map, "r1-a-1", Some("r1-a"));
register_call(&mut map, "r1-a-2", Some("r1-a"));
register_call(&mut map, "r1-b-1", Some("r1-b"));
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("r1", AbortPolicy::AbortDependents);
assert_eq!(
aborted,
vec![
"r1-a".to_string(),
"r1-a-1".to_string(),
"r1-a-2".to_string(),
"r1-b".to_string(),
"r1-b-1".to_string(),
]
);
assert!(cascade.pending.contains("r1"));
assert!(!cascade.pending.contains("r1-a"));
assert!(!cascade.pending.contains("r1-b"));
assert!(!cascade.pending.contains("r1-a-1"));
assert!(!cascade.pending.contains("r1-a-2"));
assert!(!cascade.pending.contains("r1-b-1"));
}
#[test]
fn cascade_abort_continue_running_aborts_only_unstarted_descendants() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
register_call(&mut map, "r1-a", Some("r1"));
register_call(&mut map, "r1-b", Some("r1"));
register_call(&mut map, "r1-a-1", Some("r1-a"));
map.mark_started("r1-a");
// r1-b and r1-a-1 are unstarted
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("r1", AbortPolicy::ContinueRunning);
assert_eq!(aborted, vec!["r1-a-1".to_string(), "r1-b".to_string()]);
assert!(cascade.pending.contains("r1"));
assert!(cascade.pending.contains("r1-a"));
assert!(!cascade.pending.contains("r1-b"));
assert!(!cascade.pending.contains("r1-a-1"));
}
#[test]
fn cascade_abort_continue_running_aborts_all_when_none_started() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
register_call(&mut map, "r1-a", Some("r1"));
register_call(&mut map, "r1-b", Some("r1"));
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("r1", AbortPolicy::ContinueRunning);
assert_eq!(aborted, vec!["r1-a".to_string(), "r1-b".to_string()]);
assert!(!cascade.pending.contains("r1-a"));
assert!(!cascade.pending.contains("r1-b"));
}
#[test]
fn cascade_abort_depth_three_aborts_all_descendants() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "root", None);
register_call(&mut map, "root-a", Some("root"));
register_call(&mut map, "root-b", Some("root"));
register_call(&mut map, "root-a-1", Some("root-a"));
register_call(&mut map, "root-a-2", Some("root-a"));
register_call(&mut map, "root-a-1-x", Some("root-a-1"));
register_call(&mut map, "root-a-1-y", Some("root-a-1"));
register_call(&mut map, "root-b-1", Some("root-b"));
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("root", AbortPolicy::AbortDependents);
assert_eq!(
aborted,
vec![
"root-a".to_string(),
"root-a-1".to_string(),
"root-a-1-x".to_string(),
"root-a-1-y".to_string(),
"root-a-2".to_string(),
"root-b".to_string(),
"root-b-1".to_string(),
]
);
assert!(cascade.pending.contains("root"));
assert_eq!(cascade.pending.len(), 1);
}
#[test]
fn cascade_abort_root_with_no_descendants_returns_empty() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "lonely", None);
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("lonely", AbortPolicy::AbortDependents);
assert!(aborted.is_empty());
assert!(cascade.pending.contains("lonely"));
}
#[test]
fn cascade_abort_only_aborts_descendants_not_siblings() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
register_call(&mut map, "r2", None);
register_call(&mut map, "r1-a", Some("r1"));
register_call(&mut map, "r2-a", Some("r2"));
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("r1", AbortPolicy::AbortDependents);
assert_eq!(aborted, vec!["r1-a".to_string()]);
assert!(cascade.pending.contains("r1"));
assert!(cascade.pending.contains("r2"));
assert!(cascade.pending.contains("r2-a"));
assert!(!cascade.pending.contains("r1-a"));
}
#[test]
fn cascade_abort_handles_mixed_call_and_subscribe_entries() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
register_subscribe(&mut map, "r1-sub", Some("r1"));
register_call(&mut map, "r1-sub-child", Some("r1-sub"));
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("r1", AbortPolicy::AbortDependents);
assert_eq!(
aborted,
vec!["r1-sub".to_string(), "r1-sub-child".to_string(),]
);
assert!(cascade.pending.contains("r1"));
assert_eq!(cascade.pending.len(), 1);
}
#[test]
fn cascade_abort_continue_running_with_started_descendant_keeps_its_unstarted_children() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
register_call(&mut map, "r1-a", Some("r1"));
register_call(&mut map, "r1-a-1", Some("r1-a"));
map.mark_started("r1-a");
// r1-a is started and continues; r1-a-1 is unstarted.
// Under ContinueRunning, r1-a-1 is aborted (conservative: still pending).
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("r1", AbortPolicy::ContinueRunning);
assert_eq!(aborted, vec!["r1-a-1".to_string()]);
assert!(cascade.pending.contains("r1-a"));
assert!(!cascade.pending.contains("r1-a-1"));
}
#[test]
fn cascade_abort_abort_dependents_aborts_started_descendants_too() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
register_call(&mut map, "r1-a", Some("r1"));
register_call(&mut map, "r1-b", Some("r1"));
map.mark_started("r1-a");
map.mark_started("r1-b");
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("r1", AbortPolicy::AbortDependents);
assert_eq!(aborted, vec!["r1-a".to_string(), "r1-b".to_string()]);
assert!(!cascade.pending.contains("r1-a"));
assert!(!cascade.pending.contains("r1-b"));
}
#[test]
fn find_descendants_does_not_include_root() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
register_call(&mut map, "r1-a", Some("r1"));
let cascade = AbortCascade::new(&mut map);
let descendants = cascade.find_descendants("r1");
assert_eq!(descendants, vec!["r1-a".to_string()]);
assert!(!descendants.contains(&"r1".to_string()));
}
#[test]
fn cascade_abort_default_policy_is_abort_dependents() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
register_call(&mut map, "r1-a", Some("r1"));
map.mark_started("r1-a");
let mut cascade = AbortCascade::new(&mut map);
let aborted_default = cascade.cascade_abort("r1", AbortPolicy::default());
assert_eq!(aborted_default, vec!["r1-a".to_string()]);
}
#[test]
fn cascade_abort_does_not_remove_root() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
register_call(&mut map, "r1-a", Some("r1"));
let mut cascade = AbortCascade::new(&mut map);
let _ = cascade.cascade_abort("r1", AbortPolicy::AbortDependents);
assert!(cascade.pending.contains("r1"));
}
#[test]
fn cascade_abort_returns_sorted_descendants_for_determinism() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
register_call(&mut map, "r1-z", Some("r1"));
register_call(&mut map, "r1-a", Some("r1"));
register_call(&mut map, "r1-m", Some("r1"));
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("r1", AbortPolicy::AbortDependents);
assert_eq!(
aborted,
vec!["r1-a".to_string(), "r1-m".to_string(), "r1-z".to_string(),]
);
}
#[test]
fn unknown_request_id_silently_discarded_no_panic() {
let mut map = PendingRequestMap::new();
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("totally-unknown", AbortPolicy::AbortDependents);
assert!(aborted.is_empty());
}
#[test]
fn cascade_abort_continue_running_started_descendant_survives() {
let mut map = PendingRequestMap::new();
register_call(&mut map, "r1", None);
register_call(&mut map, "r1-a", Some("r1"));
map.mark_started("r1-a");
let mut cascade = AbortCascade::new(&mut map);
let aborted = cascade.cascade_abort("r1", AbortPolicy::ContinueRunning);
assert!(aborted.is_empty());
assert!(cascade.pending.contains("r1-a"));
}
#[test]
fn cascade_abort_handles_call_error_unused() {
let _ = CallError::internal("unused");
}
}