Avoid unnecessary work in accessing container entries

- in sequence containers, use operator[] instead of .at() when
accessing indices guaranteed to be in bound;
- in associative containers, prefer .find() and reusing the
returned const iterator to using .contains() and .at(); while
there, make any so obtained iterators const if they are read-only.

1 files changed, 9 insertions, 2 deletions

diff --git a/src/buildtool/execution_engine/tree_operations/tree_operations_utils.cpp b/src/buildtool/execution_engine/tree_operations/tree_operations_utils.cpp
index ecf08e8e..fb7d3bf0 100644
--- a/src/buildtool/execution_engine/tree_operations/tree_operations_utils.cpp
+++ b/src/buildtool/execution_engine/tree_operations/tree_operations_utils.cpp
@@ -221,9 +221,16 @@ auto TreeOperationsUtils::SerializeGitTree(
         }
         auto it = git_entries.find(*git_hash);
         if (it == git_entries.end()) {
-            git_entries.insert({*git_hash, std::vector<GitRepo::TreeEntry>{}});
+            if (auto res = git_entries.insert(
+                    {*git_hash, std::vector<GitRepo::TreeEntry>{}});
+                res.second) {
+                it = std::move(res).first;
+            }
+            else {
+                return std::nullopt;
+            }
         }
-        git_entries.at(*git_hash).emplace_back(name, entry.info.type);
+        it->second.emplace_back(name, entry.info.type);
     }
 
     // Serialize git entries.