Introduce DatabaseDocument type

crates/milli/src/update/new/indexer/settings_changes.rs

@@ -0,0 +1,55 @@
+use std::sync::atomic::Ordering;
+use std::sync::Arc;
+
+use bumpalo::Bump;
+use rayon::iter::IndexedParallelIterator;
+use rayon::slice::ParallelSlice;
+
+use super::document_changes::IndexingContext;
+use crate::documents::PrimaryKey;
+use crate::progress::AtomicDocumentStep;
+use crate::update::new::document_change::DatabaseDocument;
+use crate::update::new::indexer::document_changes::DocumentChangeContext;
+use crate::update::new::parallel_iterator_ext::ParallelIteratorExt as _;
+use crate::update::new::steps::IndexingStep;
+use crate::update::new::thread_local::{FullySend, MostlySend, ThreadLocal};
+use crate::{DocumentId, InternalError, Result};
+pub struct DatabaseDocuments<'indexer> {
+    documents: &'indexer [DocumentId],
+    primary_key: PrimaryKey<'indexer>,
+}
+
+impl<'indexer> DatabaseDocuments<'indexer> {
+    pub fn new(documents: &'indexer [DocumentId], primary_key: PrimaryKey<'indexer>) -> Self {
+        Self { documents, primary_key }
+    }
+
+    fn iter(&self, chunk_size: usize) -> impl IndexedParallelIterator<Item = &[DocumentId]> {
+        self.documents.par_chunks(chunk_size)
+    }
+
+    fn item_to_database_document<
+        'doc, // lifetime of a single `process` call
+        T: MostlySend,
+    >(
+        &'doc self,
+        context: &'doc DocumentChangeContext<T>,
+        docid: &'doc DocumentId,
+    ) -> Result<Option<DatabaseDocument<'doc>>> {
+        let current = context.index.document(&context.rtxn, *docid)?;
+
+        let external_document_id = self.primary_key.extract_docid_from_db(
+            current,
+            &context.db_fields_ids_map,
+            &context.doc_alloc,
+        )?;
+
+        let external_document_id = external_document_id.to_bump(&context.doc_alloc);
+
+        Ok(Some(DatabaseDocument::create(*docid, external_document_id)))
+    }
+
+    fn len(&self) -> usize {
+        self.documents.len()
+    }
+}