144 lines
5.0 KiB
Python
144 lines
5.0 KiB
Python
# Copyright 2016 Virgil Dupras
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#
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# This software is licensed under the "GPLv3" License as described in the "LICENSE" file,
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# which should be included with this package. The terms are also available at
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# http://www.gnu.org/licenses/gpl-3.0.html
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import os
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import os.path as op
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import logging
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import sqlite3 as sqlite
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from core.pe.cache import string_to_colors, colors_to_string
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class SqliteCache:
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"""A class to cache picture blocks in a sqlite backend."""
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def __init__(self, db=":memory:", readonly=False):
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# readonly is not used in the sqlite version of the cache
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self.dbname = db
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self.con = None
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self._create_con()
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def __contains__(self, key):
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sql = "select count(*) from pictures where path = ?"
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result = self.con.execute(sql, [key]).fetchall()
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return result[0][0] > 0
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def __delitem__(self, key):
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if key not in self:
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raise KeyError(key)
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sql = "delete from pictures where path = ?"
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self.con.execute(sql, [key])
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# Optimized
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def __getitem__(self, key):
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if isinstance(key, int):
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sql = "select blocks from pictures where rowid = ?"
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else:
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sql = "select blocks from pictures where path = ?"
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result = self.con.execute(sql, [key]).fetchone()
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if result:
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result = string_to_colors(result[0])
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return result
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else:
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raise KeyError(key)
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def __iter__(self):
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sql = "select path from pictures"
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result = self.con.execute(sql)
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return (row[0] for row in result)
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def __len__(self):
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sql = "select count(*) from pictures"
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result = self.con.execute(sql).fetchall()
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return result[0][0]
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def __setitem__(self, path_str, blocks):
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blocks = colors_to_string(blocks)
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if op.exists(path_str):
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mtime = int(os.stat(path_str).st_mtime)
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else:
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mtime = 0
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if path_str in self:
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sql = "update pictures set blocks = ?, mtime = ? where path = ?"
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else:
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sql = "insert into pictures(blocks,mtime,path) values(?,?,?)"
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try:
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self.con.execute(sql, [blocks, mtime, path_str])
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except sqlite.OperationalError:
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logging.warning("Picture cache could not set value for key %r", path_str)
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except sqlite.DatabaseError as e:
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logging.warning("DatabaseError while setting value for key %r: %s", path_str, str(e))
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def _create_con(self, second_try=False):
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def create_tables():
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logging.debug("Creating picture cache tables.")
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self.con.execute("drop table if exists pictures")
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self.con.execute("drop index if exists idx_path")
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self.con.execute("create table pictures(path TEXT, mtime INTEGER, blocks TEXT)")
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self.con.execute("create index idx_path on pictures (path)")
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self.con = sqlite.connect(self.dbname, isolation_level=None)
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try:
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self.con.execute("select path, mtime, blocks from pictures where 1=2")
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except sqlite.OperationalError: # new db
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create_tables()
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except sqlite.DatabaseError as e: # corrupted db
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if second_try:
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raise # Something really strange is happening
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logging.warning("Could not create picture cache because of an error: %s", str(e))
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self.con.close()
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os.remove(self.dbname)
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self._create_con(second_try=True)
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def clear(self):
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self.close()
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if self.dbname != ":memory:":
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os.remove(self.dbname)
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self._create_con()
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def close(self):
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if self.con is not None:
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self.con.close()
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self.con = None
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def filter(self, func):
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to_delete = [key for key in self if not func(key)]
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for key in to_delete:
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del self[key]
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def get_id(self, path):
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sql = "select rowid from pictures where path = ?"
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result = self.con.execute(sql, [path]).fetchone()
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if result:
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return result[0]
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else:
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raise ValueError(path)
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def get_multiple(self, rowids):
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sql = "select rowid, blocks from pictures where rowid in (%s)" % ",".join(map(str, rowids))
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cur = self.con.execute(sql)
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return ((rowid, string_to_colors(blocks)) for rowid, blocks in cur)
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def purge_outdated(self):
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"""Go through the cache and purge outdated records.
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A record is outdated if the picture doesn't exist or if its mtime is greater than the one in
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the db.
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"""
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todelete = []
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sql = "select rowid, path, mtime from pictures"
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cur = self.con.execute(sql)
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for rowid, path_str, mtime in cur:
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if mtime and op.exists(path_str):
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picture_mtime = os.stat(path_str).st_mtime
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if int(picture_mtime) <= mtime:
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# not outdated
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continue
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todelete.append(rowid)
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if todelete:
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sql = "delete from pictures where rowid in (%s)" % ",".join(map(str, todelete))
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self.con.execute(sql)
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