From ddc76ad0dcbdf8fed3f08e69e6ad59910146a896 Mon Sep 17 00:00:00 2001
From: Kerollmops <clement@meilisearch.com>
Date: Wed, 15 Oct 2025 16:46:20 +0200
Subject: [PATCH] Delete the leftover compaction files from canceled operations

---
 crates/index-scheduler/src/processing.rs      |  1 +
 .../src/scheduler/process_batch.rs            | 40 ++++++++++++++++---
 2 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/crates/index-scheduler/src/processing.rs b/crates/index-scheduler/src/processing.rs
index cf6c8c686..16de63244 100644
--- a/crates/index-scheduler/src/processing.rs
+++ b/crates/index-scheduler/src/processing.rs
@@ -75,6 +75,7 @@ make_enum_progress! {
     pub enum TaskCancelationProgress {
         RetrievingTasks,
         CancelingUpgrade,
+        CleaningCompactionLeftover,
         UpdatingTasks,
     }
 }
diff --git a/crates/index-scheduler/src/scheduler/process_batch.rs b/crates/index-scheduler/src/scheduler/process_batch.rs
index ab17847ef..36ca68ed9 100644
--- a/crates/index-scheduler/src/scheduler/process_batch.rs
+++ b/crates/index-scheduler/src/scheduler/process_batch.rs
@@ -1,6 +1,6 @@
 use std::collections::{BTreeSet, HashMap, HashSet};
-use std::fs::File;
-use std::io::{Seek, SeekFrom};
+use std::fs::{remove_file, File};
+use std::io::{ErrorKind, Seek, SeekFrom};
 use std::panic::{catch_unwind, AssertUnwindSafe};
 use std::sync::atomic::Ordering;
 
@@ -29,6 +29,9 @@ use crate::utils::{
 };
 use crate::{Error, IndexScheduler, Result, TaskId};
 
+/// The name of the copy of the data.mdb file used during compaction.
+const DATA_MDB_COPY_NAME: &str = "data.mdb.cpy";
+
 #[derive(Debug, Default)]
 pub struct ProcessBatchInfo {
     /// The write channel congestion. None when unavailable: settings update.
@@ -562,7 +565,7 @@ impl IndexScheduler {
         let src_path = index.path().join("data.mdb");
         let pre_size = std::fs::metadata(&src_path)?.len();
 
-        let dst_path = TempPath::from_path(index.path().join("data.mdb.cpy"));
+        let dst_path = TempPath::from_path(index.path().join(DATA_MDB_COPY_NAME));
         let file = File::create(&dst_path)?;
         let mut file = tempfile::NamedTempFile::from_parts(file, dst_path);
 
@@ -912,9 +915,10 @@ impl IndexScheduler {
 
         let enqueued_tasks = &self.queue.tasks.get_status(rtxn, Status::Enqueued)?;
 
-        // 0. Check if any upgrade task was matched.
+        // 0. Check if any upgrade or compaction tasks were matched.
         //    If so, we cancel all the failed or enqueued upgrade tasks.
         let upgrade_tasks = &self.queue.tasks.get_kind(rtxn, Kind::UpgradeDatabase)?;
+        let compaction_tasks = &self.queue.tasks.get_kind(rtxn, Kind::IndexCompaction)?;
         let is_canceling_upgrade = !matched_tasks.is_disjoint(upgrade_tasks);
         if is_canceling_upgrade {
             let failed_tasks = self.queue.tasks.get_status(rtxn, Status::Failed)?;
@@ -979,7 +983,33 @@ impl IndexScheduler {
             }
         }
 
-        // 3. We now have a list of tasks to cancel, cancel them
+        // 3. If we are cancelling a compaction task, remove the tempfiles after incomplete compactions
+        for compaction_task in &tasks_to_cancel & compaction_tasks {
+            progress.update_progress(TaskCancelationProgress::CleaningCompactionLeftover);
+            let task = self.queue.tasks.get_task(rtxn, compaction_task)?.unwrap();
+            let Some(Details::IndexCompaction {
+                index_uid,
+                pre_compaction_size: _,
+                post_compaction_size: _,
+            }) = task.details
+            else {
+                unreachable!("wrong details for compaction task {compaction_task}")
+            };
+
+            let index_path = match self.index_mapper.index_mapping.get(rtxn, &index_uid)? {
+                Some(index_uuid) => self.index_mapper.index_path(index_uuid),
+                None => return Err(Error::IndexNotFound(index_uid)),
+            };
+
+            if let Err(e) = remove_file(index_path.join(DATA_MDB_COPY_NAME)) {
+                match e.kind() {
+                    ErrorKind::NotFound => (),
+                    _ => return Err(Error::IoError(e)),
+                }
+            }
+        }
+
+        // 4. We now have a list of tasks to cancel, cancel them
         let (task_progress, progress_obj) = AtomicTaskStep::new(tasks_to_cancel.len() as u32);
         progress.update_progress(progress_obj);