pindexer: avoid std::process::exit in catchup mode

It makes calling this code in any other context annoying, we can just
use normal control flow. (Insert a flashback to the workarounds in reindexer).

crates/util/cometindex/src/indexer.rs

@@ -6,29 +6,26 @@ use indexing_state::{Height, IndexingState};
 use std::sync::Arc;
 use tokio::{sync::mpsc, task::JoinSet};
 
+/// Attempt to catch up to the latest indexed block.
+///
+/// Returns whether or not we've caught up.
 #[tracing::instrument(skip_all)]
 async fn catchup(
     state: &IndexingState,
     indices: &[Arc<dyn AppView>],
     genesis: Arc<serde_json::Value>,
-    exit_on_catchup: bool,
-) -> anyhow::Result<()> {
+) -> anyhow::Result<bool> {
     if indices.len() <= 0 {
         tracing::info!(why = "no indices", "catchup completed");
-        return Ok(());
+        return Ok(true);
     }
 
     let (src_height, index_heights) = tokio::try_join!(state.src_height(), state.index_heights())?;
     tracing::info!(?src_height, ?index_heights, "catchup status");
     let lowest_index_height = index_heights.values().copied().min().unwrap_or_default();
     if lowest_index_height >= src_height {
-        if exit_on_catchup {
-            tracing::info!("catchup completed, exiting as requested");
-            std::process::exit(0);
-        } else {
-            tracing::info!(why = "already caught up", "catchup completed");
-            return Ok(());
-        }
+        tracing::info!(why = "already caught up", "catchup completed");
+        return Ok(true);
     }
 
     // Constants that influence performance.
@@ -109,7 +106,7 @@ async fn catchup(
     while let Some(res) = tasks.join_next().await {
         res??;
     }
-    Ok(())
+    Ok(false)
 }
 
 pub struct Indexer {
@@ -163,13 +160,11 @@ impl Indexer {
                 .clone(),
         );
         loop {
-            catchup(
-                &state,
-                indexes.as_slice(),
-                app_state.clone(),
-                exit_on_catchup,
-            )
-            .await?;
+            let caught_up = catchup(&state, indexes.as_slice(), app_state.clone()).await?;
+            if exit_on_catchup && caught_up {
+                tracing::info!("catchup completed, exiting as requested");
+                return Ok(());
+            }
             tokio::time::sleep(poll_ms).await;
         }
     }