Merge branch 'jt/bulk-prefetch'

"git read-tree" had a codepath where blobs are fetched one-by-one
from the promisor remote, which has been corrected to fetch in bulk.

* jt/bulk-prefetch:
  cache-tree: prefetch in partial clone read-tree
  unpack-trees: refactor prefetching code

read-cache.c

@@ -27,6 +27,7 @@
 #include "progress.h"
 #include "sparse-index.h"
 #include "csum-file.h"
+#include "promisor-remote.h"
 
 /* Mask for the name length in ce_flags in the on-disk index */
 
@@ -3663,3 +3664,25 @@ static void write_ieot_extension(struct strbuf *sb, struct index_entry_offset_ta
 		strbuf_add(sb, &buffer, sizeof(uint32_t));
 	}
 }
+
+void prefetch_cache_entries(const struct index_state *istate,
+			    must_prefetch_predicate must_prefetch)
+{
+	int i;
+	struct oid_array to_fetch = OID_ARRAY_INIT;
+
+	for (i = 0; i < istate->cache_nr; i++) {
+		struct cache_entry *ce = istate->cache[i];
+
+		if (S_ISGITLINK(ce->ce_mode) || !must_prefetch(ce))
+			continue;
+		if (!oid_object_info_extended(the_repository, &ce->oid,
+					      NULL,
+					      OBJECT_INFO_FOR_PREFETCH))
+			continue;
+		oid_array_append(&to_fetch, &ce->oid);
+	}
+	promisor_remote_get_direct(the_repository,
+				   to_fetch.oid, to_fetch.nr);
+	oid_array_clear(&to_fetch);
+}