[debug dump util] Match Infrastructure (sonic-net#1666)

What I did
HLD for Dump Utility: HLD.

Added the Logic for Match Infrastructure along with corresponding unit tests.
Note: Before merging other PR's, please merge this first

For More Info on MatchRequest and MatchEngine, Check this section in the HLD:
MatchInfra

dump/helper.py

@@ -0,0 +1,35 @@
+import os, sys
+
+def create_template_dict(dbs):
+    """ Generate a Template which will be returned by Executor Classes """
+    return {db: {'keys': [], 'tables_not_found': []} for db in dbs}
+
+def verbose_print(str):
+    if "VERBOSE" in os.environ and os.environ["VERBOSE"] == "1":
+        print(str)
+
+def handle_error(err_str, excep=False):
+    """ 
+    Handles general error conditions, if any experienced by the module,
+    Set excep = True, to raise a exception  
+    """
+    if excep:
+        raise Exception("ERROR : {}".format(err_str))
+    else:
+        print("ERROR : {}".format(err_str), file = sys.stderr)
+
+
+def handle_multiple_keys_matched_error(err_str, key_to_go_with="", excep=False):
+    if excep:
+        handle_error(err_str, True)
+    else:
+        print("ERROR (AMBIGUITY): {} \n Proceeding with the key {}".format(err_str, key_to_go_with), file = sys.stderr)
+
+
+def sort_lists(ret_template):
+    """ Used to sort the nested list returned by the template dict. """
+    for db in ret_template.keys():
+        for key in ret_template[db].keys():
+            if isinstance(ret_template[db][key], list):
+                ret_template[db][key].sort()
+    return ret_template

dump/match_infra.py

@@ -0,0 +1,300 @@
+import json, fnmatch
+from abc import ABC, abstractmethod
+from dump.helper import verbose_print
+from swsscommon.swsscommon import SonicV2Connector, SonicDBConfig
+from sonic_py_common import multi_asic
+from utilities_common.constants import DEFAULT_NAMESPACE
+
+EXCEP_DICT = {
+    "INV_REQ": "Argument should be of type MatchRequest",
+    "INV_DB": "DB provided is not valid",
+    "NO_MATCHES": "No Entries found for Table|key_pattern provided",
+    "NO_SRC": "Either one of db or file in the request should be non-empty",
+    "NO_TABLE": "No 'table' name provided",
+    "NO_KEY": "'key_pattern' cannot be empty",
+    "NO_VALUE" : "Field is provided, but no value is provided to compare with", 
+    "SRC_VAGUE": "Only one of db or file should be provided",
+    "CONN_ERR" : "Connection Error",
+    "JUST_KEYS_COMPAT": "When Just_keys is set to False, return_fields should be empty",
+    "BAD_FORMAT_RE_FIELDS": "Return Fields should be of list type",
+    "NO_ENTRIES": "No Keys found after applying the filtering criteria",
+    "FILE_R_EXEP": "Exception Caught While Reading the json cfg file provided",
+    "INV_NS": "Namespace is invalid"
+}
+
+class MatchRequest:
+    """ 
+    Request Object which should be passed to the MatchEngine  
+    
+    Attributes:
+    "table"             : A Valid Table Name
+    "key_pattern"       : Pattern of the redis-key to match. Defaults to "*". Eg: "*" will match all the keys.
+                          Supports these glob style patterns. https://redis.io/commands/KEYS               
+    "field"             : Field to check for a match,Defaults to None
+    "value"             : Value to match, Defaults to None
+    "return_fields"     : An iterable type, where each element woudld imply a field to return from all the filtered keys
+    "db"                : A Valid DB name, Defaults to "".
+    "file"              : A Valid Config JSON file, Eg: copp_cfg.json, Defaults to "".
+                          Only one of the db/file fields should have a non-empty string.
+    "just_keys"         : If true, Only Returns the keys matched. Does not return field-value pairs. Defaults to True
+    "ns"                : namespace argument, if nothing is provided, default namespace is used
+    "match_entire_list" : When this arg is set to true, entire list is matched incluing the ",". 
+                          When False, the values are split based on "," and individual items are matched with
+    """
+    def __init__(self, **kwargs):
+        self.table = kwargs["table"] if "table" in kwargs else None
+        self.key_pattern = kwargs["key_pattern"] if "key_pattern" in kwargs else "*"
+        self.field = kwargs["field"] if "field" in kwargs else None
+        self.value = kwargs["value"] if "value" in kwargs else None
+        self.return_fields = kwargs["return_fields"] if "return_fields" in kwargs else []
+        self.db = kwargs["db"] if "db" in kwargs else ""
+        self.file = kwargs["file"] if "file" in kwargs else ""
+        self.just_keys = kwargs["just_keys"] if "just_keys" in kwargs else True
+        self.ns = kwargs["ns"] if "ns" in kwargs else ""
+        self.match_entire_list = kwargs["match_entire_list"] if "match_entire_list" in kwargs else False
+        err = self.__static_checks()
+        verbose_print(str(err))
+        if err:
+            raise Exception("Static Checks for the MatchRequest Failed, Reason: \n" + err)
+
+
+    def __static_checks(self):
+
+        if not self.db and not self.file:
+            return EXCEP_DICT["NO_SRC"]
+
+        if self.db and self.file:
+            return EXCEP_DICT["SRC_VAGUE"]
+
+        if not self.db:
+            try:
+                with open(self.file) as f:
+                    json.load(f)
+            except Exception as e:
+                return EXCEP_DICT["FILE_R_EXEP"] + str(e)
+
+        if not self.file and self.db not in SonicDBConfig.getDbList():
+            return EXCEP_DICT["INV_DB"]
+
+        if not self.table:
+            return EXCEP_DICT["NO_TABLE"]
+
+        if not isinstance(self.return_fields, list):
+            return EXCEP_DICT["BAD_FORMAT_RE_FIELDS"]
+
+        if not self.just_keys and self.return_fields:
+            return EXCEP_DICT["JUST_KEYS_COMPAT"]
+
+        if self.field and not self.value:
+            return EXCEP_DICT["NO_VALUE"]
+
+        if self.ns != DEFAULT_NAMESPACE and self.ns not in multi_asic.get_namespace_list():
+            return EXCEP_DICT["INV_NS"] + " Choose From {}".format(multi_asic.get_namespace_list())
+
+        verbose_print("MatchRequest Checks Passed")
+
+        return ""
+
+    def __str__(self):
+        str = "----------------------- \n MatchRequest: \n"
+        if self.db:
+            str += "db:{} , ".format(self.db)
+        if self.file:
+            str += "file:{} , ".format(self.file) 
+        if self.table:
+            str += "table:{} , ".format(self.table)
+        if self.key_pattern:
+            str += "key_pattern:{} , ".format(self.key_pattern)
+        if self.field:
+            str += "field:{} , ".format(self.field)
+        if self.value:
+            str += "value:{} , ".format(self.value)
+        if self.just_keys:
+            str += "just_keys:True ,"
+        else:
+            str += "just_keys:False ,"
+        if len(self.return_fields) > 0:
+            str += "return_fields: " + ",".join(self.return_fields) + " "
+        if self.ns:
+            str += "namespace: , " + self.ns 
+        if self.match_entire_list:
+            str += "match_list: True , "
+        else:
+            str += "match_list: False , "
+        return str
+
+class SourceAdapter(ABC):
+    """ Source Adaptor offers unified interface to Data Sources """
+
+    def __init__(self):
+        pass
+
+    @abstractmethod
+    def connect(self, db, ns):
+        """ Return True for Success, False for failure """
+        return False
+
+    @abstractmethod
+    def getKeys(self, db, table, key_pattern):
+        return []
+
+    @abstractmethod
+    def get(self, db, key):
+        return {}
+
+    @abstractmethod
+    def hget(self, db, key, field):
+        return ""
+
+    @abstractmethod
+    def get_separator(self, db):
+        return ""
+
+class RedisSource(SourceAdapter):
+    """ Concrete Adaptor Class for connecting to Redis Data Sources """
+
+    def __init__(self):
+        self.conn = None 
+
+    def connect(self, db, ns):
+        try:
+            if not SonicDBConfig.isInit():
+                if multi_asic.is_multi_asic():
+                    SonicDBConfig.load_sonic_global_db_config()
+                else:
+                    SonicDBConfig.load_sonic_db_config()
+            self.conn = SonicV2Connector(namespace=ns, use_unix_socket_path=True) 
+            self.conn.connect(db)
+        except Exception as e:
+            verbose_print("RedisSource: Connection Failed\n" + str(e))
+            return False
+        return True
+
+    def get_separator(self, db):
+        return self.conn.get_db_separator(db)
+
+    def getKeys(self, db, table, key_pattern):       
+        return self.conn.keys(db, table + self.get_separator(db) + key_pattern)
+
+    def get(self, db, key):
+        return self.conn.get_all(db, key)
+
+    def hget(self, db, key, field):
+        return self.conn.get(db, key, field)
+
+class JsonSource(SourceAdapter):
+    """ Concrete Adaptor Class for connecting to JSON Data Sources """
+
+    def __init__(self):
+        self.json_data = None
+
+    def connect(self, db, ns):
+        try:
+            with open(db) as f:
+                self.json_data = json.load(f)
+        except Exception as e:
+            verbose_print("JsonSource: Loading the JSON file failed" + str(e))
+            return False
+        return True
+
+    def get_separator(self, db):
+        return SonicDBConfig.getSeparator("CONFIG_DB")
+
+    def getKeys(self, db, table, key_pattern):
+        if table not in self.json_data:
+            return []
+        # https://docs.python.org/3.7/library/fnmatch.html
+        kp = key_pattern.replace("[^", "[!")
+        kys = fnmatch.filter(self.json_data[table].keys(), kp)
+        return [table + self.get_separator(db) + ky for ky in kys]
+
+    def get(self, db, key):
+        sep = self.get_separator(db)
+        table, key = key.split(sep, 1)
+        return self.json_data.get(table, {}).get(key, {})
+
+    def hget(self, db, key, field):
+        sep = self.get_separator(db)
+        table, key = key.split(sep, 1)
+        return self.json_data.get(table, "").get(key, "").get(field, "")
+
+class MatchEngine:
+    """ Pass in a MatchRequest, to fetch the Matched dump from the Data sources """
+
+    def __get_source_adapter(self, req):
+        src = None
+        d_src = ""
+        if req.db:
+            d_src = req.db
+            src = RedisSource()
+        else:
+            d_src = req.file
+            src = JsonSource()
+        return d_src, src
+
+    def __create_template(self):
+        return {"error" : "", "keys" : [], "return_values" : {}}
+
+    def __display_error(self, err):
+        template = self.__create_template()
+        template['error'] = err
+        verbose_print("MatchEngine: \n" + template['error'])
+        return template
+
+    def __filter_out_keys(self, src, req, all_matched_keys):
+        # TODO: Custom Callbacks for Complex Matching Criteria
+        if not req.field:
+            return all_matched_keys
+
+        filtered_keys = []
+        for key in all_matched_keys:
+            f_values = src.hget(req.db, key, req.field)
+            if "," in f_values and not req.match_entire_list:
+                f_value = f_values.split(",")
+            else:
+                f_value = [f_values]
+            if req.value in f_value:
+                filtered_keys.append(key)
+        return filtered_keys
+
+    def __fill_template(self, src, req, filtered_keys, template):
+        for key in filtered_keys:
+            temp = {}
+            if not req.just_keys:
+                temp[key] = src.get(req.db, key)
+                template["keys"].append(temp)
+            elif len(req.return_fields) > 0:
+                template["keys"].append(key)
+                template["return_values"][key] = {}
+                for field in req.return_fields: 
+                    template["return_values"][key][field] = src.hget(req.db, key, field)
+            else:
+                template["keys"].append(key)
+        verbose_print("Return Values:" + str(template["return_values"]))
+        return template
+
+    def fetch(self, req):
+        """ Given a request obj, find its match in the data source provided """
+        if not isinstance(req, MatchRequest):
+            return self.__display_error(EXCEP_DICT["INV_REQ"])
+
+        verbose_print(str(req))
+
+        if not req.key_pattern:
+            return self.__display_error(EXCEP_DICT["NO_KEY"])
+
+        d_src, src = self.__get_source_adapter(req)
+        if not src.connect(d_src, req.ns):
+            return self.__display_error(EXCEP_DICT["CONN_ERR"])
+
+        template = self.__create_template()
+        all_matched_keys = src.getKeys(req.db, req.table, req.key_pattern)
+        if not all_matched_keys:
+            return self.__display_error(EXCEP_DICT["NO_MATCHES"])
+
+        filtered_keys = self.__filter_out_keys(src, req, all_matched_keys)
+        verbose_print("Filtered Keys:" + str(filtered_keys))
+        if not filtered_keys:
+            return self.__display_error(EXCEP_DICT["NO_ENTRIES"])
+        return self.__fill_template(src, req, filtered_keys, template)
+