From c53e35d370758685f4853dc85cb4958069b446a9 Mon Sep 17 00:00:00 2001
From: Alexander Schlemmer <alexander.schlemmer@ds.mpg.de>
Date: Tue, 24 Nov 2020 10:58:15 +0100
Subject: [PATCH] ENH: refactored cache classes to inherit from an abstract
base class
---
src/caosadvancedtools/cache.py | 64 ++++++++++++++++++++++++----------
1 file changed, 46 insertions(+), 18 deletions(-)
diff --git a/src/caosadvancedtools/cache.py b/src/caosadvancedtools/cache.py
index 620777bf..105f95d4 100644
--- a/src/caosadvancedtools/cache.py
+++ b/src/caosadvancedtools/cache.py
@@ -30,6 +30,7 @@ import sqlite3
from hashlib import sha256
from lxml import etree
+from abc import ABC, abstractmethod
import caosdb as db
@@ -50,16 +51,25 @@ def get_pretty_xml(cont):
return etree.tounicode(cont.to_xml(
local_serialization=True), pretty_print=True)
-# Increase this, when changes to the cache tables are made:
-CACHE_SCHEMA_VERSION = 2
-class Cache(object):
- """
- stores identifiables (as a hash of xml) and their respective ID.
+class AbstractCache(ABC):
+ @abstractmethod
+ def get_cache_schema_version(self):
+ """
+ A method that has to be overloaded that sets the version of the
+ SQLITE database schema. The schema is saved in table version column schema.
- This allows to retrieve the Record corresponding to an indentifiable
- without querying.
- """
+ Increase this variable, when changes to the cache tables are made.
+ """
+ pass
+
+ @abstractmethod
+ def create_cache(self):
+ """
+ Provide an overloaded function here that creates the cache in
+ the most recent version.
+ """
+ pass
def __init__(self, db_file=None, force_creation=False):
"""
@@ -96,9 +106,9 @@ class Cache(object):
except sqlite3.OperationalError:
current_schema = 1
- if current_schema > CACHE_SCHEMA_VERSION:
+ if current_schema > self.get_cache_schema_version():
raise RuntimeError("Cache is corrupt or was created with a future version of this program.")
- elif current_schema < CACHE_SCHEMA_VERSION:
+ elif current_schema < self.get_cache_schema_version():
raise RuntimeError("Cache version too old.")
def get_cache_version(self):
@@ -116,6 +126,22 @@ class Cache(object):
return version_row[0][0]
finally:
conn.close()
+
+
+# TODO: A better name would be IdentifiablesCache
+class Cache(AbstractCache):
+ """
+ stores identifiables (as a hash of xml) and their respective ID.
+
+ This allows to retrieve the Record corresponding to an indentifiable
+ without querying.
+ """
+
+ def get_cache_schema_version(self):
+ return 2
+
+ def __init__(self, db_file=None, force_creation=False):
+ super().__init__(db_file, force_creation)
def create_cache(self):
"""
@@ -131,7 +157,7 @@ class Cache(object):
'''CREATE TABLE identifiables (digest TEXT PRIMARY KEY, caosdb_id INTEGER, caosdb_version TEXT)''')
c.execute(
'''CREATE TABLE version (schema INTEGER)''')
- c.execute("INSERT INTO version VALUES (?)", (CACHE_SCHEMA_VERSION,))
+ c.execute("INSERT INTO version VALUES (?)", (self.get_cache_schema_version(),))
conn.commit()
conn.close()
@@ -218,7 +244,7 @@ class Cache(object):
self.insert(ehash, ent.id, ent.version.id)
-class UpdateCache(Cache):
+class UpdateCache(AbstractCache):
"""
stores unauthorized updates
@@ -226,12 +252,14 @@ class UpdateCache(Cache):
be stored in this cache such that it can be authorized and done later.
"""
- def __init__(self, db_file=None):
- if db_file is None:
- # TODO: check whether a hardcoded temp file is really wanted
- # Why not crawler_update_cache.db in current working directory?
- db_file = "/tmp/crawler_update_cache.db"
- super().__init__(db_file=db_file)
+ def get_cache_schema_version(self):
+ return 1
+
+ def get_default_file_name():
+ return "/tmp/crawler_update_cache.db"
+
+ def __init__(self, db_file=None, force_creation=False):
+ super().__init__(db_file, force_creation)
@staticmethod
def get_previous_version(cont):
--
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