Cut recurring Argon2 cost and remove per-lock WebDAV timers

Two hot-path fixes for DAV sync clients, which poll continuously:

1. App-password Basic Auth cache TTL 30s → 300s. Every cache miss costs
   a full Argon2id verification (~50-100ms CPU) plus two DB queries; at
   30s a continuously-syncing client re-paid that every 30s. 5 min cuts
   it ~10x. Safe because revoke() already invalidates the user's cached
   entries immediately; expiry/deactivation are only re-checked on a
   miss, so they now have a <=5 min grace window (comparable to a JWT
   access-token lifetime) — documented on the constant.

2. WebDAV lock store: replace the tokio::spawn + sleep scheduled per
   acquire/refresh with Moka's per-entry Expiry policy. Office clients
   refresh locks constantly, leaving thousands of orphaned sleeping
   timers pinned in the runtime that were never cancelled. by_path now
   carries the exact per-lock TTL via LockExpiry (no background tasks);
   by_token keeps a 24h backstop and resolves through by_path, so a
   lingering reverse-index entry can never resurrect an expired lock.
   Adds unit tests for the expiry policy and acquire/refresh/release
   (the module had none).

https://claude.ai/code/session_0193Hff42gaA962wThxMGSd1

src/infrastructure/services/webdav_lock_service.rs

@@ -1,15 +1,23 @@
 //! WebDAV lock store backed by Moka (in-memory cache with per-entry TTL).
 //!
-//! Locks are automatically evicted when their timeout expires, preventing
-//! orphaned locks from accumulating.  Two caches are maintained:
+//! Each lock expires automatically at its own RFC 4918 `Timeout`, enforced
+//! by Moka's [`Expiry`](moka::Expiry) policy. There are **no background
+//! tasks and no per-lock timers** — Office clients refresh locks
+//! constantly, and spawning a `sleep` future per acquire/refresh used to
+//! leave thousands of orphaned timers pinned in the runtime. Two caches are
+//! maintained:
 //!
-//! - `by_path`  : path → `LockEntry`  (for LOCK conflict detection)
-//! - `by_token` : token → path        (for fast UNLOCK / refresh lookups)
+//! - `by_path`  : path → `LockEntry`  (source of truth; precise per-lock TTL)
+//! - `by_token` : token → path        (reverse index for UNLOCK / refresh)
 //!
-//! Both caches share the same TTL so entries disappear together.
+//! `by_path` carries the exact per-lock TTL via `Expiry`; `by_token` keeps a
+//! 24 h backstop TTL. A reverse-index entry that outlives its lock is
+//! harmless: every lookup resolves through `by_path`, which is
+//! authoritative, so an expired lock reads as absent even before its token
+//! mapping is evicted.
 
 use std::sync::Arc;
-use std::time::Duration;
+use std::time::{Duration, Instant};
 
 use crate::application::adapters::webdav_adapter::{LockInfo, LockScope};
 
@@ -26,6 +34,40 @@ pub struct LockEntry {
     pub path: String,
 }
 
+/// Per-entry expiration policy for the `by_path` cache.
+///
+/// Moka calls this on insert (create) and re-insert (update, i.e. refresh)
+/// to derive each lock's TTL from its own `Timeout` header — replacing the
+/// old "global TTL + one spawned timer per lock" scheme. Reads do not
+/// extend the lock (the default `expire_after_read` leaves the remaining
+/// duration untouched).
+struct LockExpiry;
+
+impl moka::Expiry<String, LockEntry> for LockExpiry {
+    fn expire_after_create(
+        &self,
+        _path: &String,
+        entry: &LockEntry,
+        _created_at: Instant,
+    ) -> Option<Duration> {
+        Some(WebDavLockStore::parse_timeout(
+            entry.info.timeout.as_deref(),
+        ))
+    }
+
+    fn expire_after_update(
+        &self,
+        _path: &String,
+        entry: &LockEntry,
+        _updated_at: Instant,
+        _remaining: Option<Duration>,
+    ) -> Option<Duration> {
+        Some(WebDavLockStore::parse_timeout(
+            entry.info.timeout.as_deref(),
+        ))
+    }
+}
+
 /// In-memory WebDAV lock store with automatic TTL-based expiration.
 ///
 /// Uses Moka's `sync::Cache` — lock-free (sharded) reads, bounded size,
@@ -42,13 +84,16 @@ impl WebDavLockStore {
     ///
     /// * `max_capacity` — upper bound on simultaneous locks (evicts LRU on overflow).
     pub fn new(max_capacity: u64) -> Self {
-        // We use `expire_after` (per-entry TTL) via insert with explicit ttl,
-        // so we configure a generous global time_to_live as a safety net.
+        // `by_path` is the source of truth: each lock expires at its own
+        // `Timeout` via the `LockExpiry` policy (no spawned timers).
         let by_path = moka::sync::Cache::builder()
             .max_capacity(max_capacity)
-            .time_to_live(Duration::from_secs(MAX_LOCK_TIMEOUT_SECS))
+            .expire_after(LockExpiry)
             .build();
 
+        // `by_token` is a reverse index; a 24 h backstop TTL bounds any
+        // mapping that outlives its lock. Lookups resolve through `by_path`,
+        // so a lingering entry here never resurrects an expired lock.
         let by_token = moka::sync::Cache::builder()
             .max_capacity(max_capacity)
             .time_to_live(Duration::from_secs(MAX_LOCK_TIMEOUT_SECS))
@@ -72,38 +117,17 @@ impl WebDavLockStore {
             return Err(existing);
         }
 
-        let ttl = Self::parse_timeout(info.timeout.as_deref());
         let entry = LockEntry {
             info,
             path: path.to_owned(),
         };
 
+        // `LockExpiry` derives the TTL from `entry.info.timeout` on insert —
+        // no spawned timer needed.
         self.by_path.insert(path.to_owned(), entry.clone());
         self.by_token
             .insert(entry.info.token.clone(), path.to_owned());
 
-        // Moka 0.12 does not expose per-entry set_expiration_after_insert at
-        // insert time.  We rely on the global `time_to_live` as an upper bound
-        // and use the `invalidate_after` helper below for custom TTL.
-        //
-        // To implement shorter-than-max TTL we schedule an async invalidation.
-        if ttl.as_secs() < MAX_LOCK_TIMEOUT_SECS {
-            let by_path = self.by_path.clone();
-            let by_token = self.by_token.clone();
-            let token = entry.info.token.clone();
-            let path_owned = path.to_owned();
-            tokio::spawn(async move {
-                tokio::time::sleep(ttl).await;
-                // Only remove if the entry still matches (wasn't refreshed/replaced)
-                if let Some(e) = by_path.get(&path_owned)
-                    && e.info.token == token
-                {
-                    by_path.invalidate(&path_owned);
-                    by_token.invalidate(&token);
-                }
-            });
-        }
-
         Ok(entry)
     }
 
@@ -120,29 +144,13 @@ impl WebDavLockStore {
         }
 
         let ttl = Self::parse_timeout(new_timeout.or(entry.info.timeout.as_deref()));
-        let timeout_str = format!("Second-{}", ttl.as_secs());
-        entry.info.timeout = Some(timeout_str.clone());
+        // Normalize the stored timeout so `LockExpiry` recomputes the new TTL
+        // from it on re-insert (Moka fires `expire_after_update`).
+        entry.info.timeout = Some(format!("Second-{}", ttl.as_secs()));
 
-        // Re-insert to reset the TTL
         self.by_path.insert(path.clone(), entry.clone());
         self.by_token.insert(token.to_owned(), path.clone());
 
-        if ttl.as_secs() < MAX_LOCK_TIMEOUT_SECS {
-            let by_path = self.by_path.clone();
-            let by_token = self.by_token.clone();
-            let token_owned = token.to_owned();
-            let path_owned = path.clone();
-            tokio::spawn(async move {
-                tokio::time::sleep(ttl).await;
-                if let Some(e) = by_path.get(&path_owned)
-                    && e.info.token == token_owned
-                {
-                    by_path.invalidate(&path_owned);
-                    by_token.invalidate(&token_owned);
-                }
-            });
-        }
-
         Some(entry)
     }
 
@@ -212,3 +220,136 @@ pub fn create_webdav_lock_store() -> Arc<WebDavLockStore> {
     // if the cap is reached, so stale entries are cleaned automatically.
     Arc::new(WebDavLockStore::new(10_000))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::application::adapters::webdav_adapter::LockType;
+    use moka::Expiry;
+
+    fn lock_info(token: &str, timeout: Option<&str>, scope: LockScope) -> LockInfo {
+        LockInfo {
+            token: token.to_owned(),
+            owner: Some("tester".to_owned()),
+            depth: "0".to_owned(),
+            timeout: timeout.map(str::to_owned),
+            scope,
+            type_: LockType::Write,
+        }
+    }
+
+    fn entry(token: &str, timeout: Option<&str>) -> LockEntry {
+        LockEntry {
+            info: lock_info(token, timeout, LockScope::Exclusive),
+            path: "/file.txt".to_owned(),
+        }
+    }
+
+    #[test]
+    fn expiry_uses_per_entry_timeout() {
+        let now = Instant::now();
+        let key = "/file.txt".to_owned();
+
+        // Explicit Second-NNN → that exact duration.
+        let e = entry("t", Some("Second-300"));
+        assert_eq!(
+            LockExpiry.expire_after_create(&key, &e, now),
+            Some(Duration::from_secs(300))
+        );
+        // Refresh path (update) recomputes from the (normalized) timeout.
+        assert_eq!(
+            LockExpiry.expire_after_update(&key, &e, now, None),
+            Some(Duration::from_secs(300))
+        );
+    }
+
+    #[test]
+    fn expiry_clamps_infinite_and_defaults_none() {
+        let now = Instant::now();
+        let key = "/file.txt".to_owned();
+
+        let infinite = entry("t", Some("Infinite"));
+        assert_eq!(
+            LockExpiry.expire_after_create(&key, &infinite, now),
+            Some(Duration::from_secs(MAX_LOCK_TIMEOUT_SECS))
+        );
+
+        let none = entry("t", None);
+        assert_eq!(
+            LockExpiry.expire_after_create(&key, &none, now),
+            Some(Duration::from_secs(DEFAULT_LOCK_TIMEOUT_SECS))
+        );
+
+        // Over-large requests are clamped to the maximum.
+        let huge = entry("t", Some("Second-999999999"));
+        assert_eq!(
+            LockExpiry.expire_after_create(&key, &huge, now),
+            Some(Duration::from_secs(MAX_LOCK_TIMEOUT_SECS))
+        );
+    }
+
+    #[test]
+    fn acquire_get_release_roundtrip() {
+        let store = WebDavLockStore::new(16);
+        let info = lock_info("urn:token-1", Some("Second-600"), LockScope::Exclusive);
+
+        let acquired = store.acquire("/a.txt", info).expect("acquire");
+        assert_eq!(acquired.info.token, "urn:token-1");
+
+        // Resolvable by both indexes.
+        assert_eq!(
+            store.get_by_path("/a.txt").map(|e| e.info.token.clone()),
+            Some("urn:token-1".to_owned())
+        );
+        assert_eq!(
+            store.get_by_token("urn:token-1").map(|e| e.path.clone()),
+            Some("/a.txt".to_owned())
+        );
+
+        assert!(store.release("urn:token-1"));
+        assert!(store.get_by_path("/a.txt").is_none());
+        assert!(store.get_by_token("urn:token-1").is_none());
+        // Releasing an unknown token reports nothing removed.
+        assert!(!store.release("urn:token-1"));
+    }
+
+    #[test]
+    fn exclusive_lock_conflicts() {
+        let store = WebDavLockStore::new(16);
+        store
+            .acquire(
+                "/a.txt",
+                lock_info("urn:token-1", Some("Second-600"), LockScope::Exclusive),
+            )
+            .expect("first acquire");
+
+        let conflict = store.acquire(
+            "/a.txt",
+            lock_info("urn:token-2", Some("Second-600"), LockScope::Exclusive),
+        );
+        assert!(conflict.is_err());
+        // The original holder is returned so the caller can report it.
+        assert_eq!(conflict.unwrap_err().info.token, "urn:token-1");
+    }
+
+    #[test]
+    fn refresh_normalizes_timeout_and_keeps_lock() {
+        let store = WebDavLockStore::new(16);
+        store
+            .acquire(
+                "/a.txt",
+                lock_info("urn:token-1", Some("Infinite"), LockScope::Exclusive),
+            )
+            .expect("acquire");
+
+        let refreshed = store
+            .refresh("urn:token-1", Some("Second-120"))
+            .expect("refresh");
+        assert_eq!(refreshed.info.timeout.as_deref(), Some("Second-120"));
+        // Still present and still addressable by token.
+        assert!(store.get_by_token("urn:token-1").is_some());
+
+        // Refreshing an unknown token yields None.
+        assert!(store.refresh("urn:unknown", Some("Second-120")).is_none());
+    }
+}