FreeBSD: fix for get_linux_distro() and lru_cache (#59)

Since `is_FreeBSD()` is used a lot, which uses `system_info()`, which uses `get_linux_distro()` we add caching, by decorating the following functions with `@lru_cache`:

- get_architecture()
- _lsb_release()
- is_FreeBSD
- get_linux_distro
- system_info()
- _get_cmdline()

Since [functools](https://docs.python.org/3/library/functools.html) only exists in Python 3, only python 3 will benefit from this improvement. For python 2, our shim is just a pass-thru. Too bad, but, also… https://pythonclock.org/

The main motivation here was, at first, to cache more, following the style of _lsb_release.
That is now consolidated under this very same roof.

LP: #1815030

1 files changed, 19 insertions, 0 deletions

diff --git a/cloudinit/tests/test_util.py b/cloudinit/tests/test_util.py
index f4f95e92..64ed82ea 100644
--- a/cloudinit/tests/test_util.py
+++ b/cloudinit/tests/test_util.py
@@ -387,6 +387,11 @@ class TestUdevadmSettle(CiTestCase):
 @mock.patch('os.path.exists')
 class TestGetLinuxDistro(CiTestCase):
 
+    def setUp(self):
+        # python2 has no lru_cache, and therefore, no cache_clear()
+        if hasattr(util.get_linux_distro, "cache_clear"):
+            util.get_linux_distro.cache_clear()
+
     @classmethod
     def os_release_exists(self, path):
         """Side effect function"""
@@ -399,6 +404,12 @@ class TestGetLinuxDistro(CiTestCase):
         if path == '/etc/redhat-release':
             return 1
 
+    @classmethod
+    def freebsd_version_exists(self, path):
+        """Side effect function """
+        if path == '/bin/freebsd-version':
+            return 1
+
     @mock.patch('cloudinit.util.load_file')
     def test_get_linux_distro_quoted_name(self, m_os_release, m_path_exists):
         """Verify we get the correct name if the os-release file has
@@ -417,6 +428,14 @@ class TestGetLinuxDistro(CiTestCase):
         dist = util.get_linux_distro()
         self.assertEqual(('ubuntu', '16.04', 'xenial'), dist)
 
+    @mock.patch('cloudinit.util.subp')
+    def test_get_linux_freebsd(self, m_subp, m_path_exists):
+        """Verify we get the correct name and release name on FreeBSD."""
+        m_path_exists.side_effect = TestGetLinuxDistro.freebsd_version_exists
+        m_subp.return_value = ("12.0-RELEASE-p10\n", '')
+        dist = util.get_linux_distro()
+        self.assertEqual(('freebsd', '12.0-RELEASE-p10', ''), dist)
+
     @mock.patch('cloudinit.util.load_file')
     def test_get_linux_centos6(self, m_os_release, m_path_exists):
         """Verify we get the correct name and release name on CentOS 6."""