[eeprom_tlv_info] Optimize EEPROM data process by using visitor patte…

…rn (#193)

Remove EEPROM cache file and use DB instead

1. Use visitor pattern accessing EEPROM data
2. Provide utility functions to access redis data base

.gitignore

@@ -11,3 +11,5 @@ sonic_platform_common.egg-info/
 # Unit test / coverage reports
 .coverage
 htmlcov/
+coverage.xml
+test-results.xml

sonic_platform_base/sonic_eeprom/eeprom_base.py

@@ -27,6 +27,8 @@ def __init__(self, path, format, start, status, readonly):
  self.s = start
  self.u = status
  self.r = readonly
+ # Warning: the following members are deprecated, the parsed EEPROM data is stored in the
+ # Redis STATE_DB, cached data should be fetched from STATE_DB.EEPROM_INFO. 
  self.cache_name = None
  self.cache_update_needed = False
  self.lock_file = None
@@ -47,6 +49,9 @@ def check_status(self):
  return 'ok'
 
  def set_cache_name(self, name):
+ # Warning: this method is deprecated, the parsed EEPROM data is stored in the
+ # Redis STATE_DB, cached data should be fetched from STATE_DB.EEPROM_INFO. 
+
  # before accessing the eeprom we acquire an exclusive lock on the eeprom file.
  # this will prevent a race condition where multiple instances of this app
  # could try to update the cache at the same time
@@ -214,6 +219,9 @@ def open_eeprom(self):
  using_eeprom = True
  eeprom_file = self.p
  try:
+ # Warning: cache file is deprecated, the parsed EEPROM data is stored in the
+ # Redis STATE_DB, cached data should be fetched from STATE_DB.EEPROM_INFO. This
+ # code need to be adjusted once cache file is completely removing from the system.
  if os.path.isfile(self.cache_name):
  eeprom_file = self.cache_name
  using_eeprom = False
@@ -240,6 +248,9 @@ def read_eeprom_bytes(self, byteCount, offset=0):
  # expect, the file may be corrupt. Delete it and try again, this
  # time reading from the actual EEPROM.
  if len(o) != byteCount and not self.cache_update_needed:
+ # Warning: cache file is deprecated, the parsed EEPROM data is stored in the
+ # Redis STATE_DB, cached data should be fetched from STATE_DB.EEPROM_INFO. This
+ # code needs to be adjusted once cache file is completely removed from the system.
  os.remove(self.cache_name)
  self.cache_update_needed = True
  F.close()
@@ -277,6 +288,9 @@ def write_eeprom(self, e):
  self.write_cache(e)
 
  def write_cache(self, e):
+ # Warning: this method is deprecated, the parsed EEPROM data is stored in the
+ # Redis STATE_DB, cached data should be fetched from STATE_DB.EEPROM_INFO. 
+
  if self.cache_name:
  F = None
  try:
@@ -290,6 +304,9 @@ def write_cache(self, e):
  F.close()
 
  def update_cache(self, e):
+ # Warning: this method is deprecated, the parsed EEPROM data is stored in the
+ # Redis STATE_DB, cached data should be fetched from STATE_DB.EEPROM_INFO. 
+
  if self.cache_update_needed:
  self.write_cache(e)
  fcntl.flock(self.lock_file, fcntl.LOCK_UN)