[cmis] add read only cache decorator (#562)

setup.py

@@ -49,6 +49,7 @@
         'sonic_platform_base.sonic_xcvr.api.public',
         'sonic_platform_base.sonic_xcvr.codes',
         'sonic_platform_base.sonic_xcvr.codes.public',
+        'sonic_platform_base.sonic_xcvr.utils',
         'sonic_platform_base.sonic_xcvr.api.credo',
         'sonic_platform_base.sonic_xcvr.mem_maps.credo',
         'sonic_platform_base.sonic_xcvr.codes.credo',

sonic_platform_base/sfp_base.py

@@ -479,3 +479,9 @@ def get_xcvr_api(self):
         if self._xcvr_api is None:
             self.refresh_xcvr_api()
         return self._xcvr_api
+
+    def remove_xcvr_api(self):
+        """
+        Removes the cached XcvrApi so that the next get_xcvr_api() call will refresh it.
+        """
+        self._xcvr_api = None

sonic_platform_base/sonic_xcvr/api/public/cmis.py

@@ -18,6 +18,7 @@
 from .cmisVDM import CmisVdmApi
 import time
 from collections import defaultdict
+from ...utils.cache import read_only_cached_api_return
 
 logger = logging.getLogger(__name__)
 logger.addHandler(logging.NullHandler())
@@ -82,6 +83,16 @@ class CmisApi(XcvrApi):
     LowPwrRequestSW = 4
     LowPwrAllowRequestHW = 6
 
+    # Default caching enabled; control via classmethod
+    cache_enabled = True
+
+    @classmethod
+    def set_cache_enabled(cls, enabled: bool):
+        """
+        Set the cache_enabled flag to control read_only_cached_api_return behavior.
+        """
+        cls.cache_enabled = bool(enabled)
+
     def __init__(self, xcvr_eeprom):
         super(CmisApi, self).__init__(xcvr_eeprom)
         self.vdm = CmisVdmApi(xcvr_eeprom) if not self.is_flat_memory() else None
@@ -152,12 +163,14 @@ def get_vdm_unfreeze_status(self):
         '''
         return self.xcvr_eeprom.read(consts.VDM_UNFREEZE_DONE)
 
+    @read_only_cached_api_return
     def get_manufacturer(self):
         '''
         This function returns the manufacturer of the module
         '''
         return self.xcvr_eeprom.read(consts.VENDOR_NAME_FIELD)
 
+    @read_only_cached_api_return
     def get_model(self):
         '''
         This function returns the part number of the module
@@ -170,42 +183,49 @@ def get_cable_length_type(self):
         '''
         return "Length Cable Assembly(m)"
 
+    @read_only_cached_api_return
     def get_cable_length(self):
         '''
         This function returns the cable length of the module
         '''
         return self.xcvr_eeprom.read(consts.LENGTH_ASSEMBLY_FIELD)
 
+    @read_only_cached_api_return
     def get_vendor_rev(self):
         '''
         This function returns the revision level for part number provided by vendor
         '''
         return self.xcvr_eeprom.read(consts.VENDOR_REV_FIELD)
 
+    @read_only_cached_api_return
     def get_serial(self):
         '''
         This function returns the serial number of the module
         '''
         return self.xcvr_eeprom.read(consts.VENDOR_SERIAL_NO_FIELD)
 
+    @read_only_cached_api_return
     def get_module_type(self):
         '''
         This function returns the SFF8024Identifier (module type / form-factor). Table 4-1 in SFF-8024 Rev4.6
         '''
         return self.xcvr_eeprom.read(consts.ID_FIELD)
 
+    @read_only_cached_api_return
     def get_module_type_abbreviation(self):
         '''
         This function returns the SFF8024Identifier (module type / form-factor). Table 4-1 in SFF-8024 Rev4.6
         '''
         return self.xcvr_eeprom.read(consts.ID_ABBRV_FIELD)
 
+    @read_only_cached_api_return
     def get_connector_type(self):
         '''
         This function returns module connector. Table 4-3 in SFF-8024 Rev4.6
         '''
         return self.xcvr_eeprom.read(consts.CONNECTOR_FIELD)
 
+    @read_only_cached_api_return
     def get_module_hardware_revision(self):
         '''
         This function returns the module hardware revision
@@ -217,6 +237,7 @@ def get_module_hardware_revision(self):
         hw_rev = [str(num) for num in [hw_major_rev, hw_minor_rev]]
         return '.'.join(hw_rev)
 
+    @read_only_cached_api_return
     def get_cmis_rev(self):
         '''
         This function returns the CMIS version the module complies to
@@ -531,6 +552,7 @@ def is_copper(self):
         media_intf = self.get_module_media_type()
         return media_intf == "passive_copper_media_interface" if media_intf else None
 
+    @read_only_cached_api_return
     def is_flat_memory(self):
         return self.xcvr_eeprom.read(consts.FLAT_MEM_FIELD) is not False
 
@@ -802,6 +824,7 @@ def get_tx_los(self):
             tx_los_final.append(bool(tx_los[key]))
         return tx_los_final
 
+    @read_only_cached_api_return
     def get_tx_disable_support(self):
         return not self.is_flat_memory() and self.xcvr_eeprom.read(consts.TX_DISABLE_SUPPORT_FIELD)
 
@@ -873,6 +896,7 @@ def set_power_override(self, power_override, power_set):
     def get_transceiver_thresholds_support(self):
         return not self.is_flat_memory()
 
+    @read_only_cached_api_return
     def get_lpmode_support(self):
         power_class = self.xcvr_eeprom.read(consts.POWER_CLASS_FIELD)
         if power_class is None:
@@ -914,13 +938,15 @@ def get_module_media_interface(self):
         else:
             return 'Unknown media interface'
 
+    @read_only_cached_api_return
     def is_coherent_module(self):
         '''
         Returns True if the module follow C-CMIS spec, False otherwise
         '''
         mintf = self.get_module_media_interface()
         return False if 'ZR' not in mintf else True
 
+    @read_only_cached_api_return
     def get_datapath_init_duration(self):
         '''
         This function returns the duration of datapath init
@@ -933,6 +959,7 @@ def get_datapath_init_duration(self):
         value = float(duration)
         return value * DATAPATH_INIT_DURATION_MULTIPLIER if value <= DATAPATH_INIT_DURATION_OVERRIDE_THRESHOLD else value
 
+    @read_only_cached_api_return
     def get_datapath_deinit_duration(self):
         '''
         This function returns the duration of datapath deinit
@@ -942,6 +969,7 @@ def get_datapath_deinit_duration(self):
         duration = self.xcvr_eeprom.read(consts.DP_PATH_DEINIT_DURATION)
         return float(duration) if duration is not None else 0
 
+    @read_only_cached_api_return
     def get_datapath_tx_turnon_duration(self):
         '''
         This function returns the duration of datapath tx turnon
@@ -951,6 +979,7 @@ def get_datapath_tx_turnon_duration(self):
         duration = self.xcvr_eeprom.read(consts.DP_TX_TURNON_DURATION)
         return float(duration) if duration is not None else 0
 
+    @read_only_cached_api_return
     def get_datapath_tx_turnoff_duration(self):
         '''
         This function returns the duration of datapath tx turnoff
@@ -960,6 +989,7 @@ def get_datapath_tx_turnoff_duration(self):
         duration = self.xcvr_eeprom.read(consts.DP_TX_TURNOFF_DURATION)
         return float(duration) if duration is not None else 0
 
+    @read_only_cached_api_return
     def get_module_pwr_up_duration(self):
         '''
         This function returns the duration of module power up
@@ -969,6 +999,7 @@ def get_module_pwr_up_duration(self):
         duration = self.xcvr_eeprom.read(consts.MODULE_PWRUP_DURATION)
         return float(duration) if duration is not None else 0
 
+    @read_only_cached_api_return
     def get_module_pwr_down_duration(self):
         '''
         This function returns the duration of module power down
@@ -1587,7 +1618,6 @@ def get_module_level_flag(self):
                       'aux2_low_alarm_flag': aux2_low_alarm_flag,
                       'aux2_high_warn_flag': aux2_high_warn_flag,
                       'aux2_low_warn_flag': aux2_low_warn_flag}
-
         aux1_high_alarm_flag = bool((module_flag_byte2 >> 0) & 0x1)
         aux1_low_alarm_flag = bool((module_flag_byte2 >> 1) & 0x1)
         aux1_high_warn_flag = bool((module_flag_byte2 >> 2) & 0x1)
@@ -2670,6 +2700,7 @@ def get_datapath_deinit(self):
             return None
         return [bool(datapath_deinit & (1 << lane)) for lane in range(self.NUM_CHANNELS)]
 
+    @read_only_cached_api_return
     def get_application_advertisement(self):
         """
         Get the application advertisement of the CMIS transceiver
@@ -2699,6 +2730,8 @@ def get_application_advertisement(self):
                 logger.error('Failed to read APPLS_ADVT_FIELD_PAGE01: ' + str(e))
                 return ret
 
+        media_type = self.xcvr_eeprom.read(consts.MEDIA_TYPE_FIELD)
+        prefix = map.get(media_type)
         for app in range(1, 16):
             buf = {}
 
@@ -2708,7 +2741,6 @@ def get_application_advertisement(self):
                 continue
             buf['host_electrical_interface_id'] = val
 
-            prefix = map.get(self.xcvr_eeprom.read(consts.MEDIA_TYPE_FIELD))
             if prefix is None:
                 continue
             key = "{}_{}".format(prefix, app)
@@ -3175,3 +3207,4 @@ def get_error_description(self):
         return 'OK'
 
     # TODO: other XcvrApi methods
+

sonic_platform_base/sonic_xcvr/utils/__init__.py

@@ -0,0 +1 @@
+# utils package for transceiver common utilities

sonic_platform_base/sonic_xcvr/utils/cache.py

@@ -0,0 +1,19 @@
+from collections import abc
+import os
+
+def read_only_cached_api_return(func):
+    """Cache until func() returns a non-None, non-empty collections cache_value."""
+    cache_name = f'_{func.__name__}_cache'
+    def wrapper(self):
+        if not self.cache_enabled:
+            return func(self)
+        if not hasattr(self, cache_name):
+            cache_value = func(self)
+            setattr(self, cache_name, cache_value)
+        else:
+            cache_value = getattr(self, cache_name)
+            if cache_value is None or (isinstance(cache_value, abc.Iterable) and not cache_value):
+                cache_value = func(self)
+                setattr(self, cache_name, cache_value)
+        return cache_value
+    return wrapper