From 8942c38bda724a75f6be217b50188eb63bed9504 Mon Sep 17 00:00:00 2001
From: Pekka Enberg <penberg@iki.fi>
Date: Sun, 26 Jan 2025 10:52:58 +0200
Subject: [PATCH] core: Fix Statement::reset()

The first rule of writing fast programs: don't use dynamic memory
allocation!

Brings back some performance for the `SELECT 1` micro-benchmark,
although we're still not where we need to be.
---
 core/lib.rs      |  3 +--
 core/vdbe/mod.rs | 13 +++++++++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/core/lib.rs b/core/lib.rs
index f03c73e00..628d21150 100644
--- a/core/lib.rs
+++ b/core/lib.rs
@@ -486,8 +486,7 @@ impl Statement {
     }
 
     pub fn reset(&mut self) {
-        let state = vdbe::ProgramState::new(self.program.max_registers);
-        self.state = state
+        self.state.reset();
     }
 }
 
diff --git a/core/vdbe/mod.rs b/core/vdbe/mod.rs
index dae7f8806..a06412aa3 100644
--- a/core/vdbe/mod.rs
+++ b/core/vdbe/mod.rs
@@ -258,6 +258,19 @@ impl ProgramState {
     }
 
     pub fn reset(&mut self) {
+        self.pc = 0;
+        self.btree_table_cursors.borrow_mut().clear();
+        self.btree_index_cursors.borrow_mut().clear();
+        self.pseudo_cursors.borrow_mut().clear();
+        self.sorter_cursors.borrow_mut().clear();
+        let max_registers = self.registers.len();
+        self.registers.clear();
+        self.registers.resize(max_registers, OwnedValue::Null);
+        self.last_compare = None;
+        self.deferred_seek = None;
+        self.ended_coroutine.clear();
+        self.regex_cache.like.clear();
+        self.interrupted = false;
         self.parameters.clear();
     }
 }