Refactored sdp serializers
This commit is contained in:
@@ -0,0 +1,510 @@
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from os import path
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import os
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from datetime import datetime, date
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import hashlib
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import json
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import zlib
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from sdp.sheerkaSerializer import Serializer
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def json_default_converter(o):
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"""
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Default formatter for json
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It's used when the json serializer does not know
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how to serialise a type
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:param o:
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:return:
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"""
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if isinstance(o, (date, datetime)):
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return o.isoformat()
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class Event(object):
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"""
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Class that represents something that modifies the state of the system
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"""
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def __init__(self, message="", user="kodjo", date=datetime.now()):
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self.version = 1
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self.user = user
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self.date = date
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self.message = message
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def get_digest(self):
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"""
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Returns the digest of the event
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:return: hexa form of the sha256
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"""
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if not isinstance(self.message, str):
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raise NotImplementedError
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return hashlib.sha256(f"{self.user}{self.date}{self.message}".encode("utf-8")).hexdigest()
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def to_json(self):
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return json.dumps(self.__dict__, default=json_default_converter)
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def from_json(self, json_message):
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self.user = json_message["user"]
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self.date = datetime.fromisoformat(json_message["date"])
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self.message = json_message["message"]
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class State:
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"""
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Class that represents the state of the system (dictionary of all known entries)
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"""
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def __init__(self):
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self.version = 1
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self.date = None
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self.parents = []
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self.events = []
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self.data = {}
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def update(self, entry, obj, append=True):
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obj_to_use = {str(obj.get_key()): obj} if hasattr(obj, "get_key") else obj
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if entry not in self.data:
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self.data[entry] = obj_to_use
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elif isinstance(obj_to_use, dict):
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if append:
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self.data[entry].update(obj_to_use)
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else:
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self.data[entry] = obj_to_use
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elif isinstance(self.data[entry], list):
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if append:
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self.data[entry].append(obj_to_use)
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else:
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self.data[entry] = obj_to_use
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else:
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if append:
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self.data[entry] = [self.data[entry], obj_to_use]
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else:
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self.data[entry] = obj_to_use
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def remove(self, entry, filter):
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if filter is None:
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del (self.data[entry])
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elif isinstance(self.data[entry], dict):
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keys_to_remove = []
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for key, element in self.data[entry].items():
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if filter(key, element):
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keys_to_remove.append(key)
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for key in keys_to_remove:
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del (self.data[entry][key])
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elif not isinstance(self.data[entry], list):
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if filter(self.data[entry]):
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del (self.data[entry])
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else:
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for element in self.data[entry]:
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if filter(element):
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self.data[entry].remove(element)
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def get_digest(self):
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as_json = json.dumps(self.__dict__, default=json_default_converter)
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return hashlib.sha256(as_json.encode("utf-8")).hexdigest()
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def contains(self, entry, key):
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if entry not in self.data:
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return False
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if not isinstance(self.data[entry], dict):
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return False
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return key in self.data[entry]
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class SheerkaDataProvider:
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"""Manages the state of the system"""
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EventFolder = "events"
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StateFolder = "state"
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CacheFolder = "cache"
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HeadFile = "HEAD"
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KeysFile = "keys"
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def __init__(self, root=None):
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self.root = path.abspath(path.join(path.expanduser("~"), ".sheerka")) \
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if root is None \
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else path.abspath(root)
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if not path.exists(self.root):
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os.makedirs(self.root)
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self.serializer = Serializer()
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def add(self, event: Event, entry, obj):
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"""
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Adds obj to the entry 'entry'
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:param event: events that triggers the update of the state
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:param entry: entry of the state to update
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:param obj: obj to insert or add
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:return: new sha256 of the state
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"""
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event_digest = self.save_event(event)
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snapshot = self.get_snapshot()
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state = self.load_state(snapshot)
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# check uniqueness, cannot add the same key twice
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obj_key = str(obj.get_key()) if hasattr(obj, "get_key") else None
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if state.contains(entry, obj_key):
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raise IndexError(f"{entry}.{obj_key}")
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elif isinstance(obj, dict):
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for k in obj:
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if state.contains(entry, k):
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raise IndexError(f"{entry}.{k}")
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state.parents = [] if snapshot is None else [snapshot]
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state.events = [event_digest]
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state.date = datetime.now()
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state.update(entry, obj if obj_key is None else {obj_key: obj})
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new_snapshot = self.save_state(state)
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self.set_snapshot(new_snapshot)
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return new_snapshot
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def add_with_auto_key(self, event: Event, entry, obj):
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"""
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Add obj to entry. An autogenerated key created for obj
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:param event:
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:param entry:
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:param obj:
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:return:
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"""
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next_key = self.get_next_key(entry)
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if hasattr(obj, "set_key"):
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obj.set_key(next_key)
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return self.add(event, entry, {next_key: obj})
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def add_unique(self, event: Event, entry, obj):
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"""Add an entry and make sure it's unique"""
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event_digest = self.save_event(event)
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snapshot = self.get_snapshot()
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state = self.load_state(snapshot)
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state.parents = [] if snapshot is None else [snapshot]
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state.events = [event_digest]
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state.date = datetime.now()
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if entry not in state.data:
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state.data[entry] = {obj}
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else:
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state.data[entry].add(obj)
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new_snapshot = self.save_state(state)
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self.set_snapshot(new_snapshot)
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return new_snapshot
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def set(self, event: Event, entry, obj):
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"""
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Add or replace an element
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:param event:
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:param entry:
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:param obj:
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:return:
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"""
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event_digest = self.save_event(event)
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snapshot = self.get_snapshot()
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state = self.load_state(snapshot)
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state.parents = [] if snapshot is None else [snapshot]
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state.events = [event_digest]
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state.date = datetime.now()
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obj_key = str(obj.get_key()) if hasattr(obj, "get_key") else None
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state.update(entry, obj if obj_key is None else {obj_key: obj}, append=False)
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new_snapshot = self.save_state(state)
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self.set_snapshot(new_snapshot)
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return new_snapshot
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def modify(self, event: Event, entry, key, obj):
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"""
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Updates an existing element when element are saved by key
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:param event:
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:param entry:
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:param key: key of the object to update
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:param obj: new data
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:return:
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"""
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event_digest = self.save_event(event)
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snapshot = self.get_snapshot()
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state = self.load_state(snapshot)
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if entry not in state.data:
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raise IndexError(entry)
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if key is not None and key not in state.data[entry]:
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raise IndexError(f"{entry}.{key}")
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state.parents = [] if snapshot is None else [snapshot]
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state.events = [event_digest]
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state.date = datetime.now()
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if key is None:
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state.data[entry] = obj
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else:
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state.update(entry, {key: obj})
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new_snapshot = self.save_state(state)
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self.set_snapshot(new_snapshot)
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return new_snapshot
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def list(self, entry, filter=None):
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"""
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Lists elements of entry 'entry'
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:param entry: name of the entry to list
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:param filter: filter to use
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:return: list of elements
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"""
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snapshot = self.get_snapshot()
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state = self.load_state(snapshot)
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if entry not in state.data:
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return []
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elements = state.data[entry]
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if isinstance(elements, dict):
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# manage when elements have a key
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filter_to_use = (lambda k, o: True) if filter is None else filter
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for key, element in elements.items():
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if filter_to_use(key, element):
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yield element
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else:
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# manage when no key is defined for the elements
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if not isinstance(elements, list) and not isinstance(elements, set):
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elements = [elements]
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filter_to_use = (lambda o: True) if filter is None else filter
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for element in elements:
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if filter_to_use(element):
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yield element
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def remove(self, event: Event, entry, filter=None):
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"""
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Removes elements under the entry 'entry'
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:param event: event that triggers the deletion
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:param entry:
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:param filter: filter to use
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:return: new sha256 of the state
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TODO: Remove by key
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"""
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snapshot = self.get_snapshot()
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state = self.load_state(snapshot)
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if entry not in state.data:
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raise IndexError(entry)
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event_digest = self.save_event(event)
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state.parents = [] if snapshot is None else [snapshot]
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state.events = [event_digest]
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state.date = datetime.now()
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state.remove(entry, filter)
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new_snapshot = self.save_state(state)
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self.set_snapshot(new_snapshot)
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return new_snapshot
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def get(self, entry, key=None):
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"""
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Retrieve an element by its key
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:param entry:
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:param key:
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:return:
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"""
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snapshot = self.get_snapshot()
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state = self.load_state(snapshot)
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if entry not in state.data:
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raise IndexError(entry)
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if key is not None and key not in state.data[entry]:
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raise IndexError(f"{entry}.{key}")
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return state.data[entry] if key is None else state.data[entry][key]
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def get_safe(self, entry, key=None):
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"""
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Retrieve an element by its key. Return None if the element does not exist
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:param entry:
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:param key:
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:return:
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"""
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snapshot = self.get_snapshot()
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state = self.load_state(snapshot)
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if entry not in state.data:
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return None
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if key is not None and key not in state.data[entry]:
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return None
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return state.data[entry] if key is None else state.data[entry][key]
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def exists(self, entry):
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"""
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Returns true if the entry is defined
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:param entry:
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:return:
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"""
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snapshot = self.get_snapshot()
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state = self.load_state(snapshot)
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return entry in state.data
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def save_event(self, event: Event):
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"""
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return an event, given its digest
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:param event:
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:return: digest of the event
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"""
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digest = event.get_digest()
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target_path = path.join(self.root, SheerkaDataProvider.EventFolder, digest[:24], digest)
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if path.exists(target_path):
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return digest
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if not path.exists(path.dirname(target_path)):
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os.makedirs(path.dirname(target_path))
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with open(target_path, "wb") as f:
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f.write(self.serializer.serialize(event).read())
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return digest
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def load_event(self, digest):
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"""
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return an event, given its digest
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:param digest:
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:return:
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"""
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target_path = path.join(self.root, SheerkaDataProvider.EventFolder, digest[:24], digest)
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with open(target_path, "rb") as f:
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return self.serializer.deserialize(f)
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def save_state(self, state: State):
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digest = state.get_digest()
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target_path = path.join(self.root, SheerkaDataProvider.StateFolder, digest[:24], digest)
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if path.exists(target_path):
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return digest
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if not path.exists(path.dirname(target_path)):
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os.makedirs(path.dirname(target_path))
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with open(target_path, "wb") as f:
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f.write(self.serializer.serialize(state).read())
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return digest
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def load_state(self, digest):
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if digest is None:
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return State()
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target_path = path.join(self.root, SheerkaDataProvider.StateFolder, digest[:24], digest)
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with open(target_path, "rb") as f:
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return self.serializer.deserialize(f)
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def get_cache_params(self, category, key):
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digest = hashlib.sha3_256(f"{category}:{key}".encode("utf-8")).hexdigest()
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cache_path = path.join(self.root, SheerkaDataProvider.CacheFolder, digest[:24], digest)
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return digest, cache_path
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def add_to_cache(self, category, key, obj, update=False):
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"""
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Save obj in the internal cache system
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:param category:
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:param key:
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:param obj:
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:param update:
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:return:
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"""
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digest, cache_path = self.get_cache_params(category, key)
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if path.exists(cache_path) and not update:
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return digest
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if not path.exists(path.dirname(cache_path)):
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os.makedirs(path.dirname(cache_path))
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with open(cache_path, "wb") as f:
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f.write(zlib.compress(obj.encode("utf-8"), 9))
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return digest
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def load_from_cache(self, category, key):
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"""
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Reload a compress object from the cache
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:param category:
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:param key:
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:return:
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"""
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digest, cache_path = self.get_cache_params(category, key)
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if not path.exists(cache_path):
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raise IndexError(f"{category}.{key}")
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with open(cache_path, "rb") as f:
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return zlib.decompress(f.read()).decode("utf-8")
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def remove_from_cache(self, category, key):
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"""
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:param category:
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:param key:
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:return:
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"""
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digest, cache_path = self.get_cache_params(category, key)
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if path.exists(cache_path):
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os.remove(cache_path)
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return digest
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def in_cache(self, category, key):
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"""
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Returns true if the key is in cache
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:param category:
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:param key:
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:return:
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"""
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digest, cache_path = self.get_cache_params(category, key)
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return path.exists(cache_path)
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def get_snapshot(self):
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head_file = path.join(self.root, SheerkaDataProvider.HeadFile)
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if not path.exists(head_file):
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return None
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with open(head_file, "r") as f:
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return f.read()
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def set_snapshot(self, digest):
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head_file = path.join(self.root, SheerkaDataProvider.HeadFile)
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with open(head_file, "w") as f:
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return f.write(digest)
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def load_keys(self):
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keys_file = path.join(self.root, SheerkaDataProvider.KeysFile)
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if not path.exists(keys_file):
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keys = {}
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else:
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with open(keys_file, "r") as f:
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keys = json.load(f)
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return keys
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def save_keys(self, keys):
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keys_file = path.join(self.root, SheerkaDataProvider.KeysFile)
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with open(keys_file, "w") as f:
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json.dump(keys, f)
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def get_next_key(self, entry):
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keys = self.load_keys()
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next_key = keys.get(entry, 0) + 1
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keys[entry] = next_key
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self.save_keys(keys)
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return str(next_key)
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def set_key(self, entry, value):
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keys = self.load_keys()
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keys[entry] = value
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self.save_keys(keys)
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return str(value)
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