view sat/memory/cache.py @ 2716:06160b529da6

core (memory/sqlite): changed history constraint /!\ Database schema change /!\ History was using a unique constraint on `profile_id, timestamp, source, dest, source_res, dest_res`, which can cause trouble because several messages send quickly by the same person can have a common timestamp (specially with delayed messages where precision is second), resulting in message loss. The new constraint use `profile_id, stanza_id, source, dest` where `stanza_id` is XEP-0359 stanza_id, so it's unique by definition, and no message should be lost anymore. Because sqlite doesn't support altering table with a constraint change, we have to create new tables and copy old data to new one, which can be pretty long. Sqlite update mechanism with "specifics" has been fixed when several updates are applied (e.g. moving from v5 to v7) and a specific is in the workflow.
author Goffi <goffi@goffi.org>
date Sun, 09 Dec 2018 14:07:26 +0100
parents 56f94936df1e
children 003b8b4b56a7
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#!/usr/bin/env python2
# -*- coding: utf-8 -*-

# SAT: a jabber client
# Copyright (C) 2009-2018 Jérôme Poisson (goffi@goffi.org)

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from sat.core.log import getLogger

log = getLogger(__name__)
from sat.tools.common import regex
from sat.core import exceptions
from sat.core.constants import Const as C
import cPickle as pickle
import mimetypes
import os.path
import time

DEFAULT_EXT = ".raw"


class Cache(object):
    """generic file caching"""

    def __init__(self, host, profile):
        """
        @param profile(unicode, None): ame of the profile to set the cache for
            if None, the cache will be common for all profiles
        """
        self.profile = profile
        path_elts = [host.memory.getConfig("", "local_dir"), C.CACHE_DIR]
        if profile:
            path_elts.extend([u"profiles", regex.pathEscape(profile)])
        else:
            path_elts.append(u"common")
        self.cache_dir = os.path.join(*path_elts)

        if not os.path.exists(self.cache_dir):
            os.makedirs(self.cache_dir)

    def getPath(self, filename):
        """return cached file URL

        @param filename(unicode): cached file name (cache data or actual file)
        """
        if not filename or u"/" in filename:
            log.error(
                u"invalid char found in file name, hack attempt? name:{}".format(filename)
            )
            raise exceptions.DataError(u"Invalid char found")
        return os.path.join(self.cache_dir, filename)

    def getMetadata(self, uid):
        """retrieve metadata for cached data

        @param uid(unicode): unique identifier of file
        @return (dict, None): metadata with following keys:
            see [cacheData] for data details, an additional "path" key is the full path to cached file.
            None if file is not in cache (or cache is invalid)
        """

        uid = uid.strip()
        if not uid:
            raise exceptions.InternalError(u"uid must not be empty")
        cache_url = self.getPath(uid)
        if not os.path.exists(cache_url):
            return None

        try:
            with open(cache_url, "rb") as f:
                cache_data = pickle.load(f)
        except IOError:
            log.warning(u"can't read cache at {}".format(cache_url))
            return None
        except pickle.UnpicklingError:
            log.warning(u"invalid cache found at {}".format(cache_url))
            return None

        try:
            eol = cache_data["eol"]
        except KeyError:
            log.warning(u"no End Of Life found for cached file {}".format(uid))
            eol = 0
        if eol < time.time():
            log.debug(
                u"removing expired cache (expired for {}s)".format(time.time() - eol)
            )
            return None

        cache_data["path"] = self.getPath(cache_data["filename"])
        return cache_data

    def getFilePath(self, uid):
        """retrieve absolute path to file

        @param uid(unicode): unique identifier of file
        @return (unicode, None): absolute path to cached file
            None if file is not in cache (or cache is invalid)
        """
        metadata = self.getMetadata(uid)
        if metadata is not None:
            return metadata["path"]

    def cacheData(self, source, uid, mime_type=None, max_age=None, filename=None):
        """create cache metadata and file object to use for actual data

        @param source(unicode): source of the cache (should be plugin's import_name)
        @param uid(unicode): an identifier of the file which must be unique
        @param mime_type(unicode): MIME type of the file to cache
            it will be used notably to guess file extension
        @param max_age(int, None): maximum age in seconds
            the cache metadata will have an "eol" (end of life)
            None to use default value
            0 to ignore cache (file will be re-downloaded on each access)
        @param filename: if not None, will be used as filename
            else one will be generated from uid and guessed extension
        @return(file): file object opened in write mode
            you have to close it yourself (hint: use with statement)
        """
        cache_url = self.getPath(uid)
        if filename is None:
            if mime_type:
                ext = mimetypes.guess_extension(mime_type, strict=False)
                if ext is None:
                    log.warning(
                        u"can't find extension for MIME type {}".format(mime_type)
                    )
                    ext = DEFAULT_EXT
                elif ext == u".jpe":
                    ext = u".jpg"
            else:
                ext = DEFAULT_EXT
                mime_type = None
            filename = uid + ext
        if max_age is None:
            max_age = C.DEFAULT_MAX_AGE
        cache_data = {
            u"source": source,
            u"filename": filename,
            u"eol": int(time.time()) + max_age,
            u"mime_type": mime_type,
        }
        file_path = self.getPath(filename)

        with open(cache_url, "wb") as f:
            pickle.dump(cache_data, f, protocol=2)

        return open(file_path, "wb")