Synnefo » Pithos

# Copyright 2011 GRNET S.A. All rights reserved.

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import os

import time

import sqlite3

import logging

import types

import hashlib

import shutil

import pickle

from base import BaseBackend

logger = logging.getLogger(__name__)

class SimpleBackend(BaseBackend):

    """A simple backend.

    Uses SQLite for storage.

    """

    def __init__(self, db):

        self.hash_algorithm = 'sha1'

        self.block_size = 128 * 1024 # 128KB

        basepath = os.path.split(db)[0]

        if basepath and not os.path.exists(basepath):

            os.makedirs(basepath)

        self.con = sqlite3.connect(db)

        sql = '''create table if not exists objects (

                    name text, tstamp text, primary key (name))'''

        self.con.execute(sql)

        sql = '''create table if not exists metadata (

                    name text, key text, value text, primary key (name, key))'''

        self.con.execute(sql)

        sql = '''create table if not exists versions (

                    object_id int, version int, size int, primary key (object_id, version))'''

        self.con.execute(sql)

        sql = '''create table if not exists blocks (

                    block_id text, data blob, primary key (block_id))'''

        self.con.execute(sql)

        sql = '''create table if not exists hashmaps (

                    version_id int, pos int, block_id text, primary key (version_id, pos))'''

        self.con.execute(sql)

        self.con.commit()

    def get_account_meta(self, account):

        """Return a dictionary with the account metadata."""

        logger.debug("get_account_meta: %s", account)

        count, bytes = self._get_pathstats(account)

        # Proper count.

        sql = 'select count(name) from objects where name glob ? and not name glob ?'

        c = self.con.execute(sql, (account + '/*', account + '/*/*'))

        row = c.fetchone()

        count = row[0]

        meta = self._get_metadata(account)

        meta.update({'name': account, 'count': count, 'bytes': bytes})

        return meta

    def update_account_meta(self, account, meta, replace=False):

        """Update the metadata associated with the account."""

        logger.debug("update_account_meta: %s %s %s", account, meta, replace)

        self._update_metadata(account, None, None, meta, replace)

    def put_container(self, account, name):

        """Create a new container with the given name."""

        logger.debug("put_container: %s %s", account, name)

        try:

            path, link, tstamp = self._get_containerinfo(account, name)

        except NameError:

            path = os.path.join(account, name)

            link = self._put_linkinfo(path)

        else:

            raise NameError('Container already exists')

        self._update_metadata(account, name, None, None)

    def delete_container(self, account, name):

        """Delete the container with the given name."""

        logger.debug("delete_container: %s %s", account, name)

        path, link, tstamp = self._get_containerinfo(account, name)

        count, bytes = self._get_pathstats(path)

        if count > 0:

            raise IndexError('Container is not empty')

        self._del_path(path)

        self._update_metadata(account, None, None, None)

    def get_container_meta(self, account, name):

        """Return a dictionary with the container metadata."""

        logger.debug("get_container_meta: %s %s", account, name)

        path, link, tstamp = self._get_containerinfo(account, name)

        count, bytes = self._get_pathstats(path)

        meta = self._get_metadata(path)

        meta.update({'name': name, 'count': count, 'bytes': bytes, 'created': tstamp})

        return meta

    def update_container_meta(self, account, name, meta, replace=False):

        """Update the metadata associated with the container."""

        logger.debug("update_container_meta: %s %s %s %s", account, name, meta, replace)

        path, link, tstamp = self._get_containerinfo(account, name)

        self._update_metadata(account, name, None, meta, replace)

    def list_containers(self, account, marker=None, limit=10000):

        """Return a list of containers existing under an account."""

        logger.debug("list_containers: %s %s %s", account, marker, limit)

        return self._list_objects(account, '', '/', marker, limit, False, [])

    def list_objects(self, account, container, prefix='', delimiter=None, marker=None, limit=10000, virtual=True, keys=[]):

        """Return a list of objects existing under a container."""

        logger.debug("list_objects: %s %s %s %s %s %s", account, container, prefix, delimiter, marker, limit)

        path, link, tstamp = self._get_containerinfo(account, container)

        return self._list_objects(path, prefix, delimiter, marker, limit, virtual, keys)

    def list_object_meta(self, account, name):

        """Return a list with all the container's object meta keys."""

        logger.debug("list_object_meta: %s %s", account, name)

        path, link, tstamp = self._get_containerinfo(account, name)

        sql = 'select distinct key from metadata where name like ?'

        c = self.con.execute(sql, (path + '/%',))

        return [x[0] for x in c.fetchall()]

    def get_object_meta(self, account, container, name):

        """Return a dictionary with the object metadata."""

        logger.debug("get_object_meta: %s %s %s", account, container, name)

        path, link, tstamp = self._get_containerinfo(account, container)

        path, link, tstamp, version, size = self._get_objectinfo(account, container, name)

        meta = self._get_metadata(path)

        meta.update({'name': name, 'bytes': size, 'version': version, 'created': tstamp})

        return meta

    def update_object_meta(self, account, container, name, meta, replace=False):

        """Update the metadata associated with the object."""

        logger.debug("update_object_meta: %s %s %s %s %s", account, container, name, meta, replace)

        path, link, tstamp = self._get_containerinfo(account, container)

        path, link, tstamp, version, size = self._get_objectinfo(account, container, name)

        if 'versioned' in meta:

            if meta['versioned']:

                if version == 0:

                    sql = 'update versions set version = 1 where object_id = ?'

                    self.con.execute(sql, (link,))

                    self.con.commit()

            else:

                if version > 0:

                    self._del_uptoversion(link, version)

                    sql = 'update versions set version = 0 where object_id = ?'

                    self.con.execute(sql, (link,))

                    self.con.commit()

            del(meta['versioned'])

        self._update_metadata(account, container, name, meta, replace)

    def get_object_hashmap(self, account, container, name, version=None):

        """Return the object's size and a list with partial hashes."""

        logger.debug("get_object_hashmap: %s %s %s %s", account, container, name, version)

        path, link, tstamp = self._get_containerinfo(account, container)

        path, link, tstamp, version, size = self._get_objectinfo(account, container, name, version)

        sql = '''select block_id from hashmaps where version_id =

                    (select rowid from versions where object_id = ? and version = ?)

                    order by pos'''

        c = self.con.execute(sql, (link, version))

        hashmap = [x[0] for x in c.fetchall()]

        return size, hashmap

    def update_object_hashmap(self, account, container, name, size, hashmap):

        """Create/update an object with the specified size and partial hashes."""

        logger.debug("update_object_hashmap: %s %s %s %s %s", account, container, name, size, hashmap)

        path, link, tstamp = self._get_containerinfo(account, container)

        try:

            path, link, tstamp, version, s = self._get_objectinfo(account, container, name)

        except NameError:

            version = 0

        if version == 0:

            path = os.path.join(account, container, name)

            self._del_path(path, delmeta=False)

            link = self._put_linkinfo(path)

        else:

            version += 1

        sql = 'insert or replace into versions (object_id, version, size) values (?, ?, ?)'

        version_id = self.con.execute(sql, (link, version, size)).lastrowid

        for i in range(len(hashmap)):

            sql = 'insert or replace into hashmaps (version_id, pos, block_id) values (?, ?, ?)'

            self.con.execute(sql, (version_id, i, hashmap[i]))

        self.con.commit()

    def copy_object(self, account, src_container, src_name, dest_container, dest_name, dest_meta={}, replace_meta=False):

        """Copy an object's data and metadata."""

        logger.debug("copy_object: %s %s %s %s %s %s %s", account, src_container, src_name, dest_container, dest_name, dest_meta, replace_meta)

        size, hashmap = self.get_object_hashmap(account, src_container, src_name)

        self.update_object_hashmap(account, dest_container, dest_name, size, hashmap)

        if not replace_meta:

            meta = self._get_metadata(os.path.join(account, src_container, src_name))

            meta.update(dest_meta)

        else:

            meta = dest_meta

        self._update_metadata(account, dest_container, dest_name, meta, replace_meta)

    def move_object(self, account, src_container, src_name, dest_container, dest_name, dest_meta={}, replace_meta=False):

        """Move an object's data and metadata."""

        logger.debug("move_object: %s %s %s %s %s %s %s", account, src_container, src_name, dest_container, dest_name, dest_meta, replace_meta)

        self.copy_object(account, src_container, src_name, dest_container, dest_name, dest_meta, replace_meta)

        self.delete_object(account, src_container, src_name)

    def delete_object(self, account, container, name):

        """Delete an object."""

        logger.debug("delete_object: %s %s %s", account, container, name)

        path, link, tstamp = self._get_containerinfo(account, container)

        path = os.path.join(account, container, name)

        link, tstamp = self._get_linkinfo(path)

        self._del_path(path)

        self._update_metadata(account, container, None, None)

    def get_block(self, hash):

        """Return a block's data."""

        logger.debug("get_block: %s", hash)

        c = self.con.execute('select data from blocks where block_id = ?', (hash,))

        row = c.fetchone()

        if row:

            return str(row[0])

        else:

            raise NameError('Block does not exist')

    def put_block(self, data):

        """Create a block and return the hash."""

        logger.debug("put_block: %s", len(data))

        h = hashlib.new(self.hash_algorithm)

        h.update(data.rstrip('\x00'))

        hash = h.hexdigest()

        sql = 'insert or ignore into blocks (block_id, data) values (?, ?)'

        self.con.execute(sql, (hash, buffer(data)))

        self.con.commit()

        return hash

    def update_block(self, hash, data, offset=0):

        """Update a known block and return the hash."""

        logger.debug("update_block: %s %s %s", hash, len(data), offset)

        if offset == 0 and len(data) == self.block_size:

            return self.put_block(data)

        src_data = self.get_block(hash)

        bs = self.block_size

        if offset < 0 or offset > bs or offset + len(data) > bs:

            raise IndexError('Offset or data outside block limits')

        dest_data = src_data[:offset] + data + src_data[offset + len(data):]

        return self.put_block(dest_data)

    def _get_linkinfo(self, path):

        c = self.con.execute('select rowid, tstamp from objects where name = ?', (path,))

        row = c.fetchone()

        if row:

            return str(row[0]), str(row[1])

        else:

            raise NameError('Object does not exist')

    def _put_linkinfo(self, path):

        sql = 'insert into objects (name, tstamp) values (?, ?)'

        id = self.con.execute(sql, (path, int(time.time()))).lastrowid

        self.con.commit()

        return str(id)

    def _get_containerinfo(self, account, container):

        path = os.path.join(account, container)

        try:

            link, tstamp = self._get_linkinfo(path)

        except NameError:

            raise NameError('Container does not exist')

        return path, link, tstamp

    def _get_objectinfo(self, account, container, name, version=None):

        path = os.path.join(account, container, name)

        link, tstamp = self._get_linkinfo(path)

        if not version: # If zero or None.

            sql = '''select version, size from versions v,

                        (select object_id, max(version) as m from versions

                            where object_id = ? group by object_id) as g

                        where v.object_id = g.object_id and v.version = g.m'''

            c = self.con.execute(sql, (link,))

        else:

            sql = 'select version, size from versions where object_id = ? and version = ?'

            c = self.con.execute(sql, (link, version))

        row = c.fetchone()

        if not row:

            raise IndexError('Version does not exist')

        return path, link, tstamp, int(row[0]), int(row[1])

    def _get_pathstats(self, path):

        """Return count and sum of size of all objects under path."""

        sql = '''select count(o), total(size) from (

                    select v.object_id as o, v.size from versions v,

                        (select object_id, max(version) as m from versions where object_id in

                            (select rowid from objects where name like ?) group by object_id) as g

                        where v.object_id = g.object_id and v.version = g.m

                    union

                    select rowid as o, 0 as size from objects where name like ?

                        and rowid not in (select object_id from versions))'''

        c = self.con.execute(sql, (path + '/%', path + '/%'))

        row = c.fetchone()

        return int(row[0]), int(row[1])

    def _list_objects(self, path, prefix='', delimiter=None, marker=None, limit=10000, virtual=True, keys=[]):

        cont_prefix = path + '/'

        if keys and len(keys) > 0:

            sql = '''select distinct o.name from objects o, metadata m where o.name like ? and

                        m.name = o.name and m.key in (%s) order by o.name'''

            sql = sql % ', '.join('?' * len(keys))

            param = (cont_prefix + prefix + '%',) + tuple(keys)

        else:

            sql = 'select name from objects where name like ? order by name'

            param = (cont_prefix + prefix + '%',)

        c = self.con.execute(sql, param)

        objects = [x[0][len(cont_prefix):] for x in c.fetchall()]

        if delimiter:

            pseudo_objects = []

            for x in objects:

                pseudo_name = x

                i = pseudo_name.find(delimiter, len(prefix))

                if not virtual:

                    # If the delimiter is not found, or the name ends

                    # with the delimiter's first occurence.

                    if i == -1 or len(pseudo_name) == i + len(delimiter):

                        pseudo_objects.append(pseudo_name)

                else:

                    # If the delimiter is found, keep up to (and including) the delimiter.

                    if i != -1:

                        pseudo_name = pseudo_name[:i + len(delimiter)]

                    if pseudo_name not in pseudo_objects:

                        pseudo_objects.append(pseudo_name)

            objects = pseudo_objects

        start = 0

        if marker:

            try:

                start = objects.index(marker) + 1

            except ValueError:

                pass

        if not limit or limit > 10000:

            limit = 10000

        return objects[start:start + limit]

    def _get_metadata(self, path):

        sql = 'select key, value from metadata where name = ?'

        c = self.con.execute(sql, (path,))

        return dict(c.fetchall())

    def _put_metadata(self, path, meta, replace=False):

        if replace:

            sql = 'delete from metadata where name = ?'

            self.con.execute(sql, (path,))

        for k, v in meta.iteritems():

            sql = 'insert or replace into metadata (name, key, value) values (?, ?, ?)'

            self.con.execute(sql, (path, k, v))

        self.con.commit()

    def _update_metadata(self, account, container, name, meta, replace=False):

        """Recursively update metadata and set modification time."""

        modified = {'modified': int(time.time())}

        if not meta:

            meta = {}

        meta.update(modified)

        path = (account, container, name)

        for x in reversed(range(3)):

            if not path[x]:

                continue

            self._put_metadata(os.path.join(*path[:x+1]), meta, replace)

            break

        for y in reversed(range(x)):

            self._put_metadata(os.path.join(*path[:y+1]), modified)

    def _del_uptoversion(self, link, version):

        sql = '''delete from hashmaps where version_id

                    (select rowid from versions where object_id = ? and version < ?)'''

        self.con.execute(sql, (link, version))

        self.con.execute('delete from versions where object_id = ?', (link,))

        self.con.commit()

    def _del_path(self, path, delmeta=True):

        sql = '''delete from hashmaps where version_id in

                    (select rowid from versions where object_id in

                    (select rowid from objects where name = ?))'''

        self.con.execute(sql, (path,))

        sql = '''delete from versions where object_id in

                    (select rowid from objects where name = ?)'''

        self.con.execute(sql, (path,))

        self.con.execute('delete from objects where name = ?', (path,))

        if delmeta:

            self.con.execute('delete from metadata where name = ?', (path,))

        self.con.commit()