RUST-BUG-072: preserve queued source requests

Author: Threepwood-7

crates/emulebb-ed2k/src/ed2k_server/background.rs

@@ -158,10 +158,8 @@ pub async fn search_source_via_background_session(
 
     tokio::select! {
         _ = cancel.cancelled() => Ok(Vec::new()),
-        result = tokio::time::timeout(timeout, receive_response) => {
-            let response = result
-                .with_context(|| format!("timed out waiting for ED2K background source response after {timeout:?}"))?
-                .context("ED2K background source responder dropped")?;
+        response = receive_response => {
+            let response = response.context("ED2K background source responder dropped")?;
             response.map_err(anyhow::Error::msg)
         }
     }

crates/emulebb-ed2k/src/ed2k_server/tests/background.rs

@@ -91,6 +91,61 @@ async fn background_source_search_channel_round_trips_results() {
     responder.await.unwrap();
 }
 
+#[tokio::test]
+async fn background_source_search_waits_while_queued_before_dispatch() {
+    let (handle, mut inbox) = new_ed2k_server_search_channel(1);
+    let file_hash = Ed2kHash([0x52; 16]);
+    let queued_handle = handle.clone();
+    let search = tokio::spawn(async move {
+        let cancel = CancellationToken::new();
+        search_source_via_background_session(
+            &queued_handle,
+            file_hash,
+            42,
+            Duration::from_millis(20),
+            &cancel,
+        )
+        .await
+    });
+
+    tokio::time::sleep(Duration::from_millis(60)).await;
+    let request = inbox.receiver.recv().await.unwrap();
+    match request {
+        BackgroundServerSearchRequest::Source {
+            file_hash: requested_hash,
+            timeout,
+            response,
+            ..
+        } => {
+            assert_eq!(requested_hash, file_hash);
+            assert_eq!(timeout, Duration::from_millis(20));
+            let _ = response.send(Ok(Vec::new()));
+        }
+        other => panic!("unexpected background request: {other:?}"),
+    }
+
+    assert_eq!(search.await.unwrap().unwrap(), Vec::new());
+}
+
+#[tokio::test]
+async fn background_source_search_cancel_stops_queued_wait() {
+    let (handle, _inbox) = new_ed2k_server_search_channel(1);
+    let cancel = CancellationToken::new();
+    cancel.cancel();
+
+    let results = search_source_via_background_session(
+        &handle,
+        Ed2kHash([0x53; 16]),
+        42,
+        Duration::from_secs(60),
+        &cancel,
+    )
+    .await
+    .unwrap();
+
+    assert!(results.is_empty());
+}
+
 #[tokio::test]
 async fn background_udp_source_search_preserves_responding_server() {
     let server = test_udp_obfuscated_server();

docs/active/INDEX.md

@@ -83,6 +83,7 @@ items.
 | [RUST-BUG-069](items/RUST-BUG-069.md) | Major | DONE | Pace failed direct source retries per endpoint |
 | [RUST-BUG-070](items/RUST-BUG-070.md) | Major | DONE | Pace Kad source refreshes across retry attempts |
 | [RUST-BUG-071](items/RUST-BUG-071.md) | Major | DONE | Wait until direct source retry cooldown before reattempting |
+| [RUST-BUG-072](items/RUST-BUG-072.md) | Major | DONE | Do not expire queued connected-server source requests before dispatch |
 
 ## Refactors (`REF`)
 

docs/active/items/RUST-BUG-072.md

@@ -0,0 +1,74 @@
+---
+id: RUST-BUG-072
+title: Do not expire queued connected-server source requests before dispatch
+status: done
+priority: Major
+category: bug
+workflow: local
+---
+
+# RUST-BUG-072: Do not expire queued connected-server source requests before dispatch
+
+## Problem
+
+The post-`RUST-BUG-071` hide.me live-wire runs stayed VPN-bound, HighID, and
+Kad-connected, but failed to complete a payload. Packet and daemon logs showed
+that most started downloads never reached direct peers because connected-server
+source requests timed out at the caller while waiting in the background-session
+queue:
+
+- `rust-hideme-20260618T201235Z`: 18
+  `timed out waiting for ED2K background source response after 15s` failures.
+- `rust-hideme-20260618T202723Z`: 35 caller-side 15-second source-response
+  timeouts plus one in-session `OP_FOUNDSOURCES` timeout.
+
+eMuleBB MFC buffers local server source requests into TCP frames in
+`DownloadQueue.cpp` and later accepts `OP_FOUNDSOURCES` asynchronously in
+`ServerSocket.cpp`. It does not start a per-file source-response timeout before
+the request is dispatched on the connected server session. Rust used the same
+15-second timeout both inside the session driver and around the caller's
+oneshot wait, so concurrent downloads could expire before their request was
+even sent.
+
+## Acceptance
+
+- [x] Connected-server source requests still carry a timeout used after dispatch.
+- [x] Waiting in the background-session queue does not consume the dispatch
+      timeout.
+- [x] Cancellation still aborts the caller wait promptly.
+- [x] Focused unit coverage proves a queued source request can wait longer than
+      its dispatch timeout before being answered.
+- [x] The next hide.me live-wire diagnostics run shows fewer caller-side
+      connected-server source timeouts and more source acquisition opportunity.
+
+## Implementation Notes
+
+- Keep keyword searches unchanged; user-facing keyword searches still need a
+  caller-visible timeout.
+- This fix only changes connected-server source lookup queue semantics. It does
+  not increase server request rate or add new server login sessions.
+
+## Evidence
+
+- `cargo test -p emulebb-ed2k background_source_search_waits_while_queued_before_dispatch --locked`
+- `cargo test -p emulebb-ed2k background_source_search_cancel_stops_queued_wait --locked`
+- `cargo test -p emulebb-ed2k background_source_search_channel_round_trips_results --locked`
+- `cargo test -p emulebb-ed2k background_udp_source_search_preserves_responding_server --locked`
+- `python tools\rust_quality_gate.py quick`
+- Diagnostics build
+  `EMULEBB_WORKSPACE_OUTPUT_ROOT\logs\builds\20260618T210610Z-build-clients\build-result.json`:
+  Release diagnostics build passed with zero warnings.
+- Live-wire hide.me diagnostics run
+  `EMULEBB_WORKSPACE_OUTPUT_ROOT\live-wire\rust-hideme-20260618T210709Z\report.json`:
+  VPN-bound HighID run passed, started 17 downloads, completed 4 files
+  (5388230 bytes total), reached 32 peak reported sources, stayed Kad-connected
+  with 70 contacts, and captured packet diagnostics (5491 diagnostic records,
+  968 ED2K packet records, 4609 Kad UDP packet records).
+- Source-acquisition comparison:
+  `rust-hideme-20260618T201235Z` had 18 caller-side
+  `timed out waiting for ED2K background source response after 15s` failures,
+  8 direct attempts, and 0 completed files. `rust-hideme-20260618T202723Z` had
+  35 caller-side source-response timeouts, 14 direct attempts, and 0 completed
+  files. The fixed run had 0 caller-side source-response timeouts, 29 direct
+  attempts, 4 completed files, and retained the RUST-BUG-071 scheduler fix
+  (`reason=direct_sources_deferred` remained 0).