Allow using hq worker stop last

Kobzol · Kobzol · commit 5d8c2b0c7bba · 2021-11-03T17:00:17.000+01:00
diff --git a/crates/hyperqueue/src/server/client.rs b/crates/hyperqueue/src/server/client.rs
@@ -358,7 +358,12 @@ async fn handle_worker_stop(
             .filter(|(_, worker)| worker.make_info().ended.is_none())
             .map(|(_, worker)| worker.worker_id())
             .collect(),
-        _ => return ToClientMessage::Error("Invalid command was provided".parse().unwrap()),
+        Selector::LastN(n) => {
+            let mut ids: Vec<_> = state_ref.get().get_workers().keys().copied().collect();
+            ids.sort_by_key(|&k| std::cmp::Reverse(k));
+            ids.truncate(n as usize);
+            ids
+        }
     };
 
     for worker_id in worker_ids {
diff --git a/docs/deployment/worker.md b/docs/deployment/worker.md
@@ -76,11 +76,7 @@ the option `--manager <pbs/slurm>` to tell the worker that it should expect a sp
 If you have started a worker manually, and you want to stop it, you can use the `hq worker stop` command[^2]:
 
 ```bash
-# Stop a specific worker
-$ hq worker stop <worker-id>
-
-# Stop all workers
-$ hq worker stop all
+$ hq worker stop <selector>
 ```
 
 [^2]: You can use various [shortcuts](../tips/cli-shortcuts.md#id-selector) to select multiple workers at once.
diff --git a/docs/tips/cli-shortcuts.md b/docs/tips/cli-shortcuts.md
@@ -16,6 +16,7 @@ select multiple IDs at once or to reference the most recently created ID:
     - `hq worker stop all` - stop all workers
     - `hq cancel all` - cancel all jobs
 - `last` The most recently created ID
+    - `hq worker stop last` - stop most recently connected worker 
     - `hq cancel last` - cancel most recently submitted job
 
 You can also combine the first two types of selectors with a comma. For example, the command
@@ -29,7 +30,6 @@ would stop workers with IDs `1`, `3`, `5`, `6`, `7` and `8`.
 ### Supported commands and options
 - `hq submit --array=<selector>`
 - `hq worker stop <selector>`
-    - does not support `last`
 - `hq job <selector>`
     - does not support `all` (use `hq jobs` instead)
 - `hq cancel <selector>`
diff --git a/tests/test_worker.py b/tests/test_worker.py
@@ -86,6 +86,17 @@ def test_worker_stop_all(hq_env: HqEnv):
         hq_env.check_process_exited(process)
 
 
+def test_worker_stop_last(hq_env: HqEnv):
+    hq_env.start_server()
+    processes = [hq_env.start_worker() for i in range(4)]
+
+    wait_for_worker_state(hq_env, [1, 2, 3, 4], ["RUNNING" for i in range(4)]),
+    hq_env.command(["worker", "stop", "last"])
+    wait_for_worker_state(hq_env, [4], ["STOPPED" for i in range(4)]),
+
+    hq_env.check_process_exited(processes[3])
+
+
 def test_worker_list_only_online(hq_env: HqEnv):
     hq_env.start_server()
     hq_env.start_workers(2)
