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, 13 insertions, 6 deletions

diff --git a/tests/unittests/test_net.py b/tests/unittests/test_net.py
index 0f45dc38..01119e0a 100644
--- a/tests/unittests/test_net.py
+++ b/tests/unittests/test_net.py
@@ -4576,6 +4576,7 @@ class TestNetRenderers(CiTestCase):
                           priority=['sysconfig', 'eni'])
 
     @mock.patch("cloudinit.net.renderers.netplan.available")
+    @mock.patch("cloudinit.net.renderers.sysconfig.available")
     @mock.patch("cloudinit.net.renderers.sysconfig.available_sysconfig")
     @mock.patch("cloudinit.net.renderers.sysconfig.available_nm")
     @mock.patch("cloudinit.net.renderers.eni.available")
@@ -4583,14 +4584,16 @@ class TestNetRenderers(CiTestCase):
     def test_sysconfig_selected_on_sysconfig_enabled_distros(self, m_distro,
                                                              m_eni, m_sys_nm,
                                                              m_sys_scfg,
+                                                             m_sys_avail,
                                                              m_netplan):
         """sysconfig only selected on specific distros (rhel/sles)."""
 
         # Ubuntu with Network-Manager installed
-        m_eni.return_value = False       # no ifupdown (ifquery)
-        m_sys_scfg.return_value = False  # no sysconfig/ifup/ifdown
-        m_sys_nm.return_value = True     # network-manager is installed
-        m_netplan.return_value = True    # netplan is installed
+        m_eni.return_value = False        # no ifupdown (ifquery)
+        m_sys_scfg.return_value = False   # no sysconfig/ifup/ifdown
+        m_sys_nm.return_value = True      # network-manager is installed
+        m_netplan.return_value = True     # netplan is installed
+        m_sys_avail.return_value = False  # no sysconfig on Ubuntu
         m_distro.return_value = ('ubuntu', None, None)
         self.assertEqual('netplan', renderers.select(priority=None)[0])
 
@@ -4598,7 +4601,8 @@ class TestNetRenderers(CiTestCase):
         m_eni.return_value = False       # no ifupdown (ifquery)
         m_sys_scfg.return_value = False  # no sysconfig/ifup/ifdown
         m_sys_nm.return_value = True     # network-manager is installed
-        m_netplan.return_value = False    # netplan is not installed
+        m_netplan.return_value = False   # netplan is not installed
+        m_sys_avail.return_value = True  # sysconfig is available on centos
         m_distro.return_value = ('centos', None, None)
         self.assertEqual('sysconfig', renderers.select(priority=None)[0])
 
@@ -4606,7 +4610,8 @@ class TestNetRenderers(CiTestCase):
         m_eni.return_value = False       # no ifupdown (ifquery)
         m_sys_scfg.return_value = False  # no sysconfig/ifup/ifdown
         m_sys_nm.return_value = True     # network-manager is installed
-        m_netplan.return_value = False    # netplan is not installed
+        m_netplan.return_value = False   # netplan is not installed
+        m_sys_avail.return_value = True  # sysconfig is available on opensuse
         m_distro.return_value = ('opensuse', None, None)
         self.assertEqual('sysconfig', renderers.select(priority=None)[0])
 
@@ -4625,6 +4630,8 @@ class TestNetRenderers(CiTestCase):
         ]
         for (distro_name, distro_version, flavor) in distro_values:
             m_distro.return_value = (distro_name, distro_version, flavor)
+            if hasattr(util.system_info, "cache_clear"):
+                util.system_info.cache_clear()
             result = sysconfig.available()
             self.assertTrue(result)