reverse the order of the task queue

crates/index-scheduler/src/lib.rs

@@ -84,6 +84,8 @@ pub struct Query {
     pub limit: Option<u32>,
     /// The minimum [task id](`meilisearch_types::tasks::Task::uid`) to be matched
     pub from: Option<u32>,
+    /// The order used to return the tasks. By default the newest tasks are returned first and the boolean is `false`.
+    pub reverse: Option<bool>,
     /// The allowed [statuses](`meilisearch_types::tasks::Task::status`) of the matched tasls
     pub statuses: Option<Vec<Status>>,
     /// The allowed [kinds](meilisearch_types::tasks::Kind) of the matched tasks.
@@ -126,6 +128,7 @@ impl Query {
             Query {
                 limit: None,
                 from: None,
+                reverse: None,
                 statuses: None,
                 types: None,
                 index_uids: None,
@@ -706,7 +709,12 @@ impl IndexScheduler {
         let mut tasks = self.all_task_ids(rtxn)?;
 
         if let Some(from) = &query.from {
-            tasks.remove_range(from.saturating_add(1)..);
+            let range = if query.reverse.unwrap_or_default() {
+                u32::MIN..*from
+            } else {
+                from.saturating_add(1)..u32::MAX
+            };
+            tasks.remove_range(range);
         }
 
         if let Some(status) = &query.statuses {
@@ -826,7 +834,11 @@ impl IndexScheduler {
         )?;
 
         if let Some(limit) = query.limit {
-            tasks = tasks.into_iter().rev().take(limit as usize).collect();
+            tasks = if query.reverse.unwrap_or_default() {
+                tasks.into_iter().take(limit as usize).collect()
+            } else {
+                tasks.into_iter().rev().take(limit as usize).collect()
+            };
         }
 
         Ok(tasks)
@@ -951,10 +963,13 @@ impl IndexScheduler {
         let rtxn = self.env.read_txn()?;
 
         let (tasks, total) = self.get_task_ids_from_authorized_indexes(&rtxn, &query, filters)?;
-        let tasks = self.get_existing_tasks(
-            &rtxn,
-            tasks.into_iter().rev().take(query.limit.unwrap_or(u32::MAX) as usize),
-        )?;
+        let tasks = if query.reverse.unwrap_or_default() {
+            Box::new(tasks.into_iter()) as Box<dyn Iterator<Item = u32>>
+        } else {
+            Box::new(tasks.into_iter().rev()) as Box<dyn Iterator<Item = u32>>
+        };
+        let tasks =
+            self.get_existing_tasks(&rtxn, tasks.take(query.limit.unwrap_or(u32::MAX) as usize))?;
 
         let ProcessingTasks { started_at, processing, .. } =
             self.processing_tasks.read().map_err(|_| Error::CorruptedTaskQueue)?.clone();