From 8933d870312fd6733625477e9ff092d36bd97e0d Mon Sep 17 00:00:00 2001
From: Louis Dureuil <louis@meilisearch.com>
Date: Mon, 1 Sep 2025 12:10:36 +0200
Subject: [PATCH] Make backend change cancelable

---
 crates/milli/src/vector/store.rs | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/crates/milli/src/vector/store.rs b/crates/milli/src/vector/store.rs
index c39596da2..a93ae3043 100644
--- a/crates/milli/src/vector/store.rs
+++ b/crates/milli/src/vector/store.rs
@@ -104,7 +104,15 @@ impl VectorStore {
         }
     }
 
-    pub fn change_backend(&mut self, wtxn: &mut RwTxn, progress: Progress) -> crate::Result<()> {
+    pub fn change_backend<MSP>(
+        &mut self,
+        wtxn: &mut RwTxn,
+        progress: Progress,
+        must_stop_processing: MSP,
+    ) -> crate::Result<()>
+    where
+        MSP: Fn() -> bool + Sync + Send,
+    {
         if self.backend == VectorStoreBackend::Arroy {
             self.backend = VectorStoreBackend::Hannoy;
             if self.quantized {
@@ -139,6 +147,7 @@ impl VectorStore {
                     let mut rng = rand::rngs::StdRng::from_entropy();
                     let writer = hannoy::Writer::new(self._hannoy_angular_db(), index, dimensions);
                     let mut builder = writer.builder(&mut rng).progress(progress.clone());
+                    builder.cancel(must_stop_processing);
                     builder.prepare_arroy_conversion(wtxn)?;
                     builder.build::<HANNOY_M, HANNOY_M0>(wtxn)?;
                 }