Feat: Add empty json output mode

crates/hyperqueue/src/bin/hq.rs

@@ -506,8 +506,10 @@ async fn main() -> hyperqueue::Result<()> {
 
     if let Err(e) = result {
         gsettings.printer().print_error(e);
+        gsettings.printer().finalize_output();
         std::process::exit(1);
     }
 
+    gsettings.printer().finalize_output();
     Ok(())
 }

crates/hyperqueue/src/client/commands/autoalloc.rs

@@ -348,7 +348,10 @@ wasting resources."
     Ok(())
 }
 
-async fn add_queue(mut session: ClientSession, opts: AddQueueOpts) -> anyhow::Result<()> {
+async fn add_queue(
+    mut session: ClientSession,
+    opts: AddQueueOpts,
+) -> anyhow::Result<()> {
     let (parameters, dry_run) = match opts.subcmd {
         AddQueueCommand::Pbs(params) => {
             let no_dry_run = params.no_dry_run;

crates/hyperqueue/src/client/output/cli.rs

@@ -1034,6 +1034,10 @@ impl Output for CliOutput {
             job_id.to_string().color(colored::Color::Green),
         );
     }
+
+    fn finalize_output(&self) {
+        println!()
+    }
 }
 
 struct AllocationTimes {

crates/hyperqueue/src/client/output/json.rs

@@ -251,6 +251,10 @@ impl Output for JsonOutput {
     fn print_error(&self, error: Error) {
         self.print(json!({ "error": format!("{error:?}") }))
     }
+
+    fn finalize_output(&self) {
+        self.print(json!({}));
+    }
 }
 
 fn format_task_description(task_desc: &TaskDescription) -> Value {

crates/hyperqueue/src/client/output/outputs.rs

@@ -91,4 +91,7 @@ pub trait Output {
     fn print_hw(&self, descriptor: &ResourceDescriptor);
 
     fn print_error(&self, error: anyhow::Error);
+
+    // this will be called before hq quits
+    fn finalize_output(&self);
 }

crates/hyperqueue/src/client/output/quiet.rs

@@ -151,6 +151,8 @@ impl Output for Quiet {
     fn print_error(&self, error: Error) {
         eprintln!("{error:?}");
     }
+
+    fn finalize_output(&self) {}
 }
 
 fn format_status(status: &Status) -> &str {