Avoid allocating temporary strings in Channel::CreateCall().

Add `SliceFromArray()` which takes a `char*` instead of
`const string&`, to save string allocations for copying from a `char *`.

Use the new API to eliminate two string allocations and copies per call for
method and host names.

release-note: no

1 files changed, 4 insertions, 0 deletions

diff --git a/include/grpcpp/impl/codegen/slice.h b/include/grpcpp/impl/codegen/slice.h
index 8966559dc8..9cdca3ab3c 100644
--- a/include/grpcpp/impl/codegen/slice.h
+++ b/include/grpcpp/impl/codegen/slice.h
@@ -138,6 +138,10 @@ inline grpc_slice SliceFromCopiedString(const grpc::string& str) {
                                                                  str.length());
 }
 
+inline grpc_slice SliceFromArray(const char* arr, size_t len) {
+    return g_core_codegen_interface->grpc_slice_from_copied_buffer(arr, len);
+}
+
 }  // namespace grpc
 
 #endif  // GRPCPP_IMPL_CODEGEN_SLICE_H