Allow SQLite3 busy_handler to be configured with simple max number of retries

Retrying busy connections without delay is a preferred practice for performance-sensitive applications. Add support for a `database.yml` `retries` integer, which is used in a simple `busy_handler` function to retry busy connections without exponential backoff up to the max number of `retries`
.

Author: fractaledmind

activerecord/CHANGELOG.md

@@ -1,3 +1,9 @@
+*   Allow SQLite3 `busy_handler` to be configured with simple max number of `retries`
+
+    Retrying busy connections without delay is a preferred practice for performance-sensitive applications. Add support for a `database.yml` `retries` integer, which is used in a simple `busy_handler` function to retry busy connections without exponential backoff up to the max number of `retries`.
+
+    *Stephen Margheim*
+
 *   The SQLite3 adapter now supports `supports_insert_returning?`
 
     Implementing the full `supports_insert_returning?` contract means the SQLite3 adapter supports auto-populated columns (#48241) as well as custom primary keys.

activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb

@@ -712,7 +712,16 @@ def reconnect
         end
 
         def configure_connection
-          @raw_connection.busy_timeout(self.class.type_cast_config_to_integer(@config[:timeout])) if @config[:timeout]
+          if @config[:timeout] && @config[:retries]
+            raise ArgumentError, "Cannot specify both timeout and retries arguments"
+          elsif @config[:timeout]
+            @raw_connection.busy_timeout(self.class.type_cast_config_to_integer(@config[:timeout]))
+          elsif @config[:retries]
+            retries = self.class.type_cast_config_to_integer(@config[:retries])
+            raw_connection.busy_handler do |count|
+              count <= retries
+            end
+          end
 
           raw_execute("PRAGMA foreign_keys = ON", "SCHEMA")
         end