[sonic_py_common] Cache Static Information in device_info to speed up CLI response (#11696)

- Why I did it
Profiled the execution for the following cmd intfutil -c status

- How I did it
Cached the following information:
1. get_sonic_version_info()
2. get_platform_info()
None of the API exposed to the user libraries (for eg: sonic-utilities) has been modified
These methods involve reading text files or from redis. Thus, caching helped to improve the execution time

- How to verify it
Added UT's.
Verified on the device

Signed-off-by: Vivek Reddy Karri <vkarri@nvidia.com>

src/sonic-py-common/sonic_py_common/device_info.py

@@ -39,6 +39,10 @@ CHASSIS_INFO_SERIAL_FIELD = 'serial'
 CHASSIS_INFO_MODEL_FIELD = 'model'
 CHASSIS_INFO_REV_FIELD = 'revision'
 
+# Cacheable Objects
+sonic_ver_info = {}
+hw_info_dict = {}
+
 def get_localhost_info(field, config_db=None):
     try:
         # TODO: enforce caller to provide config_db explicitly and remove its default value
@@ -333,14 +337,17 @@ def get_sonic_version_info():
     if not os.path.isfile(SONIC_VERSION_YAML_PATH):
         return None
 
-    data = {}
+    global sonic_ver_info
+    if sonic_ver_info:
+        return sonic_ver_info
+
     with open(SONIC_VERSION_YAML_PATH) as stream:
         if yaml.__version__ >= "5.1":
-            data = yaml.full_load(stream)
+            sonic_ver_info = yaml.full_load(stream)
         else:
-            data = yaml.load(stream)
+            sonic_ver_info = yaml.load(stream)
 
-    return data
+    return sonic_ver_info
 
 def get_sonic_version_file():
     if not os.path.isfile(SONIC_VERSION_YAML_PATH):
@@ -354,9 +361,12 @@ def get_platform_info(config_db=None):
     """
     This function is used to get the HW info helper function
     """
-    from .multi_asic import get_num_asics
+    global hw_info_dict
 
-    hw_info_dict = {}
+    if hw_info_dict:
+        return hw_info_dict
+
+    from .multi_asic import get_num_asics
 
     version_info = get_sonic_version_info()
 

src/sonic-py-common/tests/device_info_test.py

@@ -52,6 +52,32 @@ EXPECTED_GET_MACHINE_INFO_RESULT = {
     'onie_kernel_version': '4.10.11'
 }
 
+SONIC_VERISON_YML = """\
+---
+build_version: 'test_branch.1-a8fbac59d'
+debian_version: '11.4'
+kernel_version: '5.10.0-12-2-amd64'
+asic_type: mellanox
+asic_subtype: 'mellanox'
+commit_id: 'a8fbac59d'
+branch: 'test_branch'
+release: 'master'
+libswsscommon: 1.0.0
+sonic_utilities: 1.2"""
+
+SONIC_VERISON_YML_RESULT = {
+    'build_version': 'test_branch.1-a8fbac59d', 
+    'debian_version': '11.4', 
+    'kernel_version': '5.10.0-12-2-amd64', 
+    'asic_type': 'mellanox', 
+    'asic_subtype': 'mellanox', 
+    'commit_id': 'a8fbac59d', 
+    'branch': 'test_branch', 
+    'release': 'master', 
+    'libswsscommon': '1.0.0', 
+    'sonic_utilities': 1.2
+}
+
 class TestDeviceInfo(object):
     @pytest.fixture(scope="class", autouse=True)
     def sanitize_environment(self):
@@ -83,6 +109,59 @@ class TestDeviceInfo(object):
                      "revision": SonicV2Connector.TEST_REV}
             assert result == truth
 
+    @mock.patch("os.path.isfile")
+    def test_get_sonic_version(self, mock_isfile):
+        mock_isfile.return_value = True
+        open_mocked = mock.mock_open(read_data=SONIC_VERISON_YML)
+        with mock.patch("{}.open".format(BUILTINS), open_mocked):
+            for _ in range(0,5):
+                assert device_info.get_sonic_version_info() == SONIC_VERISON_YML_RESULT
+            # Assert the file was read only once
+            open_mocked.assert_called_once_with(device_info.SONIC_VERSION_YAML_PATH)
+        
+    @mock.patch("sonic_py_common.device_info.get_platform_info")
+    def test_is_chassis(self, mock_platform_info):
+        mock_platform_info.return_value = {"switch_type": "npu"}
+        assert device_info.is_chassis() == False
+        assert device_info.is_voq_chassis() == False
+        assert device_info.is_packet_chassis() == False
+
+        mock_platform_info.return_value = {"switch_type": "voq"}
+        assert device_info.is_voq_chassis() == True
+        assert device_info.is_packet_chassis() == False
+        assert device_info.is_chassis() == True
+
+        mock_platform_info.return_value = {"switch_type": "chassis-packet"}
+        assert device_info.is_voq_chassis() == False
+        assert device_info.is_packet_chassis() == True
+        assert device_info.is_chassis() == True
+
+        mock_platform_info.return_value = {}
+        assert device_info.is_voq_chassis() == False
+        assert device_info.is_packet_chassis() == False
+        assert device_info.is_chassis() == False
+
+    @mock.patch("sonic_py_common.device_info.ConfigDBConnector", autospec=True)
+    @mock.patch("sonic_py_common.device_info.get_sonic_version_info")
+    @mock.patch("sonic_py_common.device_info.get_machine_info")
+    @mock.patch("sonic_py_common.device_info.get_hwsku")
+    def test_get_platform_info(self, mock_hwsku, mock_machine_info, mock_sonic_ver, mock_cfg_db):
+        mock_cfg_inst = mock_cfg_db.return_value
+        mock_cfg_inst.get_table.return_value = {"localhost": {"switch_type": "npu"}}
+        mock_sonic_ver.return_value = SONIC_VERISON_YML_RESULT
+        mock_machine_info.return_value = {"onie_platform" : "x86_64-mlnx_msn2700-r0"}
+        mock_hwsku.return_value = "Mellanox-SN2700"
+        for _ in range(0,5):
+            hw_info_dict = device_info.get_platform_info()
+            assert hw_info_dict["asic_type"] == "mellanox"
+            assert hw_info_dict["platform"] == "x86_64-mlnx_msn2700-r0"
+            assert hw_info_dict["hwsku"] == "Mellanox-SN2700"
+            assert hw_info_dict["switch_type"] == "npu"
+        assert mock_sonic_ver.called_once()
+        assert mock_machine_info.called_once()
+        assert mock_hwsku.called_once()
+        mock_cfg_inst.get_table.assert_called_once_with("DEVICE_METADATA")
+
     @classmethod
     def teardown_class(cls):
         print("TEARDOWN")