title: Why does my Bazel build always compile repeatly?
body: <p>In my C++ project, I am really bothered by the problem: that when i run command <code>bazel build XXX</code> or <code>bazel test XXX</code>, the Bazel process always compile files repeatly, repeatly compile files that i did't change.</p>
  <p>How should I check this problem? check my Bazel files or my Bazel cache? i am new to Bazel tools.</p>
  <p>the recompile process always start from protobuf files.</p>
  <p>i cd to directory <code>bazel-cache</code>.
  but i don't know how to check it.
  and my <code>BUILD.bazel</code> file is using <code>cc_unit_test</code>.</p>