From 27902bc5f4ccf674c1f36d54f2182dcf3615ffe6 Mon Sep 17 00:00:00 2001
From: Greg Heartsfield <scsibug@imap.cc>
Date: Tue, 27 Dec 2022 10:28:56 -0600
Subject: [PATCH] improvement: move reader mutex closer to DB connection
 acquisition

---
 src/db.rs     | 5 +++++
 src/server.rs | 7 +------
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/db.rs b/src/db.rs
index 5f17f80..8f9ba56 100644
--- a/src/db.rs
+++ b/src/db.rs
@@ -762,9 +762,14 @@ pub async fn db_query(
     pool: SqlitePool,
     query_tx: tokio::sync::mpsc::Sender<QueryResult>,
     mut abandon_query_rx: tokio::sync::oneshot::Receiver<()>,
+    safe_to_read: Arc<Mutex<u64>>,
 ) {
     let pre_spawn_start = Instant::now();
     task::spawn_blocking(move || {
+	{
+	    // if we are waiting on a checkpoint, stop until it is complete
+	    let _ = safe_to_read.blocking_lock();
+	}
         let db_queue_time = pre_spawn_start.elapsed();
         // if the queue time was very long (>5 seconds), spare the DB and abort.
         if db_queue_time > Duration::from_secs(5) {
diff --git a/src/server.rs b/src/server.rs
index ef97e29..bf77d94 100644
--- a/src/server.rs
+++ b/src/server.rs
@@ -687,13 +687,8 @@ async fn nostr_server(
                     previous_query.send(()).ok();
                                     }
 		    if s.needs_historical_events() {
-			{
-			    // acquire and immediately release lock; this ensures we do not start new queries during a wal checkpoint.
-                            let _ = safe_to_read.lock().await;
-                            trace!("passed safe_to_read lock");
-			}
                                     // start a database query.  this spawns a blocking database query on a worker thread.
-					db::db_query(s, cid.to_owned(), pool.clone(), query_tx.clone(), abandon_query_rx).await;
+					db::db_query(s, cid.to_owned(), pool.clone(), query_tx.clone(), abandon_query_rx,safe_to_read.clone()).await;
 				    }
                 },
                 Err(e) => {