Turn off sort_by_offset for keys when get LCM message

This significantly speed up lcm message retrieval.

topic: turn_off_sort_by_offset_when_get_lcm_message
GitOrigin-RevId: 0248bf9fd83cffa273c20272e06ce5145094e3e2

Author: xipeng-wang-skydio

symforce/opt/values.cc

@@ -180,16 +180,16 @@ index_entry_t Values<Scalar>::IndexEntryAt(const Key& key) const {
 }
 
 template <typename Scalar>
-void Values<Scalar>::FillLcmType(LcmType* msg) const {
+void Values<Scalar>::FillLcmType(LcmType* msg, bool sort_keys) const {
   SYM_ASSERT(msg != nullptr);
-  msg->index = CreateIndex(Keys());
+  msg->index = CreateIndex(Keys(sort_keys));
   msg->data = data_;
 }
 
 template <typename Scalar>
-typename Values<Scalar>::LcmType Values<Scalar>::GetLcmType() const {
+typename Values<Scalar>::LcmType Values<Scalar>::GetLcmType(bool sort_keys) const {
   LcmType msg;
-  FillLcmType(&msg);
+  FillLcmType(&msg, sort_keys);
   return msg;
 }
 

symforce/opt/values.h

@@ -239,8 +239,8 @@ class Values {
   /**
    * Serialize to LCM.
    */
-  void FillLcmType(LcmType* msg) const;
-  LcmType GetLcmType() const;
+  void FillLcmType(LcmType* msg, bool sort_keys = false) const;
+  LcmType GetLcmType(bool sort_keys = false) const;
 
   /**
    * Unique ID of this Values instance, incremented whenever the structure of the Values is

symforce/pybind/cc_sym.pyi

@@ -534,7 +534,7 @@ class Values:
         """
         Has zero keys.
         """
-    def get_lcm_type(self) -> values_t:
+    def get_lcm_type(self, sort_keys: bool = False) -> values_t:
         """
         Serialize to LCM.
         """

symforce/pybind/cc_values.cc

@@ -246,7 +246,8 @@ void AddValuesWrapper(pybind11::module_ module) {
               index: Ordered list of keys to include (MUST be valid for both this and others Values)
               epsilon: Small constant to avoid singularities (do not use zero)
            )")
-      .def("get_lcm_type", &sym::Valuesd::GetLcmType, "Serialize to LCM.")
+      .def("get_lcm_type", &sym::Valuesd::GetLcmType, py::arg("sort_keys") = false,
+           "Serialize to LCM.")
       .def("__repr__", [](const sym::Valuesd& values) { return fmt::format("{}", values); })
       .def(py::pickle(
           [](const sym::Valuesd& values) {  //  __getstate__

test/symforce_values_test.cc

@@ -109,7 +109,7 @@ TEMPLATE_TEST_CASE("Test values", "[values]", double, float) {
   CHECK(v.template At<Scalar>(sym::Key('f', 2)) == Scalar(15.6));
 
   // Pack to LCM
-  const typename sym::Values<Scalar>::LcmType msg = v.GetLcmType();
+  const typename sym::Values<Scalar>::LcmType msg = v.GetLcmType(true /*sort keys*/);
   CHECK(msg.index == index_2);
   CHECK(msg.data.size() == v.Data().size());