Remove jinja2_cache (#11996)

- Why I did it
As part of Persistent log level HLD , LOGLEVEL_DB content is moved to CONFIG_DB.
In addition, it was decided to remove jinja2_cache which currently appear on LOGLEVEL_DB

This cache was added to speed up template rendering in start scripts. There were a lot of them rendered during system start. This caused a delay in warm boot LAG restore time. It was tested and verified that with and without the cache we don't see any difference in this timing now. It is probably due to a lot of other optimizations done to sonic-cfggen. Since there is no noticeable improvement made by j2 cache now it is safe to remove it.

- How I did it
Remove redis_bcc.py file and and remove the bytcode_cache from sonic-sfggen

- How to verify it
Warm boot was tested with \ without this jinja2_cache and it there is no difference in performance

src/sonic-config-engine/redis_bcc.py

@@ -1,29 +0,0 @@
-import jinja2
-
-from base64 import b64encode, b64decode
-
-class RedisBytecodeCache(jinja2.BytecodeCache):
-    """ A bytecode cache for jinja2 template that stores bytecode in Redis """
-
-    REDIS_HASH = 'JINJA2_CACHE'
-
-    def __init__(self, client):
-        self._client = client
-        try:
-            self._client.connect(self._client.LOGLEVEL_DB, retry_on=False)
-        except Exception:
-            self._client = None
-
-    def load_bytecode(self, bucket):
-        if self._client is None:
-            return
-        code = self._client.get(self._client.LOGLEVEL_DB, self.REDIS_HASH, bucket.key)
-        if code is not None:
-            bucket.bytecode_from_string(b64decode(code.encode()))
-
-    def dump_bytecode(self, bucket):
-        if self._client is None:
-            return
-        self._client.set(self._client.LOGLEVEL_DB, self.REDIS_HASH,
-                         bucket.key, b64encode(bucket.bytecode_to_string()).decode())
-

src/sonic-config-engine/setup.py

@@ -43,7 +43,6 @@ py_modules = [
     'minigraph',
     'openconfig_acl',
     'portconfig',
-    'redis_bcc',
 ]
 if sys.version_info.major == 3:
     # Python 3-only modules

src/sonic-config-engine/sonic-cfggen

@@ -31,10 +31,9 @@ from config_samples import generate_sample_config, get_available_config
 from functools import partial
 from minigraph import minigraph_encoder, parse_xml, parse_device_desc_xml, parse_asic_sub_role, parse_asic_switch_type
 from portconfig import get_port_config, get_breakout_mode
-from redis_bcc import RedisBytecodeCache
 from sonic_py_common.multi_asic import get_asic_id_from_name, get_asic_device_id, is_multi_asic
 from sonic_py_common import device_info
-from swsscommon.swsscommon import SonicV2Connector, ConfigDBConnector, SonicDBConfig, ConfigDBPipeConnector
+from swsscommon.swsscommon import ConfigDBConnector, SonicDBConfig, ConfigDBPipeConnector
 
 
 PY3x = sys.version_info >= (3, 0)
@@ -241,8 +240,7 @@ def _get_jinja2_env(paths):
     Retreive Jinj2 env used to render configuration templates
     """
     loader = jinja2.FileSystemLoader(paths)
-    redis_bcc = RedisBytecodeCache(SonicV2Connector(host='127.0.0.1'))
-    env = jinja2.Environment(loader=loader, trim_blocks=True, bytecode_cache=redis_bcc)
+    env = jinja2.Environment(loader=loader, trim_blocks=True)
     env.filters['sort_by_port_index'] = sort_by_port_index
     env.filters['ipv4'] = is_ipv4
     env.filters['ipv6'] = is_ipv6