refactor: remove runtime cfg!(test) check

Won't work in integration tests and consequently all threads would be
used. To remedy this we make explicit `max_threads=Some(1)` in the
IndexerConfig::default

crates/meilisearch/src/lib.rs

@@ -501,12 +501,11 @@ fn import_dump(
     let network = dump_reader.network()?.cloned().unwrap_or_default();
     index_scheduler.put_network(network)?;
 
-    // 3.1 Use all cpus to process dump if a) `max_indexing_threads` not configured and
-    // b) we're not executing from within a test
+    // 3.1 Use all cpus to process dump if `max_indexing_threads` not configured
     let backup_config;
     let base_config = index_scheduler.indexer_config();
 
-    let indexer_config = if base_config.max_threads.is_none() && !cfg!(test) {
+    let indexer_config = if base_config.max_threads.is_none() {
         let thread_pool = ThreadPoolNoAbortBuilder::new()
             .thread_name(|index| format!("indexing-thread:{index}"))
             .num_threads(num_cpus::get())

crates/milli/src/test_index.rs

@@ -19,10 +19,7 @@ use crate::update::{
 };
 use crate::vector::settings::{EmbedderSource, EmbeddingSettings};
 use crate::vector::EmbeddingConfigs;
-use crate::{
-    db_snap, obkv_to_json, Filter, FilterableAttributesRule, Index, Search, SearchResult,
-    ThreadPoolNoAbortBuilder,
-};
+use crate::{db_snap, obkv_to_json, Filter, FilterableAttributesRule, Index, Search, SearchResult};
 
 pub(crate) struct TempIndex {
     pub inner: Index,
@@ -62,15 +59,8 @@ impl TempIndex {
         wtxn: &mut RwTxn<'t>,
         documents: Mmap,
     ) -> Result<(), crate::error::Error> {
-        let local_pool;
         let indexer_config = &self.indexer_config;
-        let pool = match &indexer_config.thread_pool {
-            Some(pool) => pool,
-            None => {
-                local_pool = ThreadPoolNoAbortBuilder::new().build().unwrap();
-                &local_pool
-            }
-        };
+        let pool = &indexer_config.thread_pool;
 
         let rtxn = self.inner.read_txn()?;
         let db_fields_ids_map = self.inner.fields_ids_map(&rtxn)?;
@@ -153,15 +143,8 @@ impl TempIndex {
         wtxn: &mut RwTxn<'t>,
         external_document_ids: Vec<String>,
     ) -> Result<(), crate::error::Error> {
-        let local_pool;
         let indexer_config = &self.indexer_config;
-        let pool = match &indexer_config.thread_pool {
-            Some(pool) => pool,
-            None => {
-                local_pool = ThreadPoolNoAbortBuilder::new().build().unwrap();
-                &local_pool
-            }
-        };
+        let pool = &indexer_config.thread_pool;
 
         let rtxn = self.inner.read_txn()?;
         let db_fields_ids_map = self.inner.fields_ids_map(&rtxn)?;
@@ -231,15 +214,8 @@ fn aborting_indexation() {
     let mut wtxn = index.inner.write_txn().unwrap();
     let should_abort = AtomicBool::new(false);
 
-    let local_pool;
     let indexer_config = &index.indexer_config;
-    let pool = match &indexer_config.thread_pool {
-        Some(pool) => pool,
-        None => {
-            local_pool = ThreadPoolNoAbortBuilder::new().build().unwrap();
-            &local_pool
-        }
-    };
+    let pool = &indexer_config.thread_pool;
 
     let rtxn = index.inner.read_txn().unwrap();
     let db_fields_ids_map = index.inner.fields_ids_map(&rtxn).unwrap();

crates/milli/src/update/indexer_config.rs

@@ -33,9 +33,13 @@ impl Default for IndexerConfig {
         #[allow(unused_mut)]
         let mut pool_builder = ThreadPoolNoAbortBuilder::new();
 
+        #[allow(unused_mut, unused_assignments)]
+        let mut max_threads = None;
+
         #[cfg(test)]
         {
             pool_builder = pool_builder.num_threads(1);
+            max_threads = Some(1);
         }
 
         let thread_pool = pool_builder
@@ -44,16 +48,16 @@ impl Default for IndexerConfig {
             .expect("failed to build default rayon thread pool");
 
         Self {
+            max_threads,
+            thread_pool,
             log_every_n: None,
             max_nb_chunks: None,
             documents_chunk_size: None,
             max_memory: None,
-            max_threads: None,
             chunk_compression_type: CompressionType::None,
             chunk_compression_level: None,
             max_positions_per_attributes: None,
             skip_index_budget: false,
-            thread_pool,
         }
     }
 }