From: Kefu Chai <kchai@redhat.com>
Date: Fri, 7 May 2021 13:36:48 +0000 (+0800)
Subject: crimson/os/seastore: use map::merge() to merge maps
X-Git-Tag: v17.1.0~2037^2~1
X-Git-Url: http://git.apps.os.sepia.ceph.com/?a=commitdiff_plain;h=79be27fd91f08d746ca6f73cd93dee184df61a1b;p=ceph.git

crimson/os/seastore: use map::merge() to merge maps

C++17's std::map allows us to merge two maps, and in this case, we can
even consume `child_result`. so map::merge() is used instead of insert()
in hope to avoid the memcpy and allocation of pair<> nodes.

Signed-off-by: Kefu Chai <kchai@redhat.com>
---

diff --git a/src/crimson/os/seastore/omap_manager/btree/omap_btree_node_impl.cc b/src/crimson/os/seastore/omap_manager/btree/omap_btree_node_impl.cc
index 4f5a7f6b5a0c6..729c54b115b78 100644
--- a/src/crimson/os/seastore/omap_manager/btree/omap_btree_node_impl.cc
+++ b/src/crimson/os/seastore/omap_manager/btree/omap_btree_node_impl.cc
@@ -232,10 +232,8 @@ OMapInnerNode::list(
 	      if (child_result.size() && start) {
 		assert(child_result.begin()->first > *start);
 	      }
-	      result.insert(
-		child_result.begin(),
-		child_result.end());
-	      biter++;
+	      result.merge(std::move(child_result));
+	      ++biter;
 	      assert(child_complete || result.size() == config.max_result_size);
 	      return list_ertr::make_ready_future<bool>(false);
 	    });