feat: support in-memory SQLite database

config.toml

@@ -22,6 +22,11 @@ description = "A newly created nostr-rs-relay.\n\nCustomize this with your own i
 # line option.
 data_directory = "."
 
+
+# Use an in-memory database instead of 'nostr.db'.
+# Caution; this will not survive a process restart!
+#in_memory = false
+
 # Database connection pool settings for subscribers:
 
 # Minimum number of SQLite reader connections

src/config.rs

@@ -25,6 +25,7 @@ pub struct Info {
 #[allow(unused)]
 pub struct Database {
     pub data_directory: String,
+    pub in_memory: bool,
     pub min_conn: u32,
     pub max_conn: u32,
 }
@@ -189,6 +190,7 @@ impl Default for Settings {
             },
             database: Database {
                 data_directory: ".".to_owned(),
+                in_memory: false,
                 min_conn: 4,
                 max_conn: 128,
             },

src/db.rs

@@ -54,13 +54,20 @@ pub fn build_pool(
     // small hack; if the database doesn't exist yet, that means the
     // writer thread hasn't finished.  Give it a chance to work.  This
     // is only an issue with the first time we run.
-    while !full_path.exists() && wait_for_db {
-        debug!("Database reader pool is waiting on the database to be created...");
-        thread::sleep(Duration::from_millis(500));
+    if !settings.database.in_memory {
+        while !full_path.exists() && wait_for_db {
+            debug!("Database reader pool is waiting on the database to be created...");
+            thread::sleep(Duration::from_millis(500));
+        }
     }
-    let manager = SqliteConnectionManager::file(&full_path)
-        .with_flags(flags)
-        .with_init(|c| c.execute_batch(STARTUP_SQL));
+    let manager = match settings.database.in_memory {
+        true => SqliteConnectionManager::memory()
+            .with_flags(flags)
+            .with_init(|c| c.execute_batch(STARTUP_SQL)),
+        false => SqliteConnectionManager::file(&full_path)
+            .with_flags(flags)
+            .with_init(|c| c.execute_batch(STARTUP_SQL)),
+    };
     let pool: SqlitePool = r2d2::Pool::builder()
         .test_on_check_out(true) // no noticeable performance hit
         .min_idle(Some(min_size))