Merge #3851

3851: Expose lastUpdate and isIndexing in /stats endpoint r=dureuill a=gentcys

# Pull Request

## Related issue
Fixes #3843

## What does this PR do?
- expose lastUpdate in `/stats` endpoint
- expose isIndex in `stats` endpoint
- add a method `is_task_processing` in index-scheduler/src/lib.rs.

## PR checklist
Please check if your PR fulfills the following requirements:
- [x] Does this PR fix an existing issue, or have you listed the changes applied in the PR description (and why they are needed)?
- [x] Have you read the contributing guidelines?
- [x] Have you made sure that the title is accurate and descriptive of the changes?

Thank you so much for contributing to Meilisearch!


Co-authored-by: Cong Chen <cong.chen@ocrlabs.com>
Co-authored-by: ManyTheFish <many@meilisearch.com>
Co-authored-by: Louis Dureuil <louis@meilisearch.com>

index-scheduler/src/lib.rs

@@ -807,6 +807,11 @@ impl IndexScheduler {
         Ok(res)
     }
 
+    // Return true if there is at least one task that is processing.
+    pub fn is_task_processing(&self) -> Result<bool> {
+        Ok(!self.processing_tasks.read().unwrap().processing.is_empty())
+    }
+
     /// Return true iff there is at least one task associated with this index
     /// that is processing.
     pub fn is_index_processing(&self, index: &str) -> Result<bool> {
@@ -1833,6 +1838,17 @@ mod tests {
         snapshot!(snapshot_index_scheduler(&index_scheduler), name: "registered_the_third_task");
     }
 
+    #[test]
+    fn test_task_is_processing() {
+        let (index_scheduler, mut handle) = IndexScheduler::test(true, vec![]);
+
+        index_scheduler.register(index_creation_task("index_a", "id")).unwrap();
+        snapshot!(snapshot_index_scheduler(&index_scheduler), name: "registered_a_task");
+
+        handle.advance_till([Start, BatchCreated]);
+        assert!(index_scheduler.is_task_processing().unwrap());
+    }
+
     /// We send a lot of tasks but notify the tasks scheduler only once as
     /// we send them very fast, we must make sure that they are all processed.
     #[test]

index-scheduler/src/snapshots/lib.rs/test_task_is_processing/registered_a_task.snap

@@ -0,0 +1,36 @@
+---
+source: index-scheduler/src/lib.rs
+---
+### Autobatching Enabled = true
+### Processing Tasks:
+[]
+----------------------------------------------------------------------
+### All Tasks:
+0 {uid: 0, status: enqueued, details: { primary_key: Some("id") }, kind: IndexCreation { index_uid: "index_a", primary_key: Some("id") }}
+----------------------------------------------------------------------
+### Status:
+enqueued [0,]
+----------------------------------------------------------------------
+### Kind:
+"indexCreation" [0,]
+----------------------------------------------------------------------
+### Index Tasks:
+index_a [0,]
+----------------------------------------------------------------------
+### Index Mapper:
+
+----------------------------------------------------------------------
+### Canceled By:
+
+----------------------------------------------------------------------
+### Enqueued At:
+[timestamp] [0,]
+----------------------------------------------------------------------
+### Started At:
+----------------------------------------------------------------------
+### Finished At:
+----------------------------------------------------------------------
+### File Store:
+
+----------------------------------------------------------------------
+

meilisearch/src/metrics.rs

@@ -50,4 +50,10 @@ lazy_static! {
         &["kind", "value"]
     )
     .expect("Can't create a metric");
+    pub static ref MEILISEARCH_LAST_UPDATE: IntGauge =
+        register_int_gauge!(opts!("meilisearch_last_update", "Meilisearch Last Update"))
+            .expect("Can't create a metric");
+    pub static ref MEILISEARCH_IS_INDEXING: IntGauge =
+        register_int_gauge!(opts!("meilisearch_is_indexing", "Meilisearch Is Indexing"))
+            .expect("Can't create a metric");
 }

meilisearch/src/routes/metrics.rs

@@ -49,6 +49,11 @@ pub async fn get_metrics(
         }
     }
 
+    if let Some(last_update) = response.last_update {
+        crate::metrics::MEILISEARCH_LAST_UPDATE.set(last_update.unix_timestamp());
+    }
+    crate::metrics::MEILISEARCH_IS_INDEXING.set(index_scheduler.is_task_processing()? as i64);
+
     let encoder = TextEncoder::new();
     let mut buffer = vec![];
     encoder.encode(&prometheus::gather(), &mut buffer).expect("Failed to encode metrics");