Personal Computer World 2008 February/PCWFEB08.iso/Software/Freeware/Miro 1.0/Miro_Installer.exe/Miro_Downloader.exe/databasesanity.pyc

Python Compiled Bytecode | 2007-11-12 | 7.2 KB | 210 lines

# Source Generated with Decompyle++
# File: in.pyc (Python 2.5)

"""Sanity checks for the databases.

This module is deprecated: database sanity checking is done by the
checkConstraints method on DDBObjects.  This is a better way to do things
because it will catch errors right when we save objects, instead of some
unknown point in the future.  We still have this code around, because it's
used to do sanity checks on old databases.

"""
import item
import feed
import util
import guide

class DatabaseInsaneError(Exception):
    pass


class SanityTest(object):
    '''Base class for the sanity test objects.'''

    def checkObject(self, object):
        '''checkObject will be called for each object in the object list.
        If there is an error return a string describing it.  If not return
        None (or just let the function hit the bottom).
        '''
        raise NotImplementedError()


    def finished(self):
        '''Called when we reach the end of the object list, SanityTest
        subclasses may implement additional checking here.'''
        pass


    def fixIfPossible(self, objectList):
        """Subclasses may implement this method if it's possible to fix broken
        databases.  The default implementation just raises a
        DatabaseInsaneError.
        """
        raise DatabaseInsaneError()



class PhontomFeedTest(SanityTest):
    """Check that no items reference a Feed that isn't around anymore."""

    def __init__(self):
        self.feedsInItems = set()
        self.topLevelFeeds = set()
        self.parentsInItems = set()
        self.topLevelParents = set()


    def checkObject(self, obj):
        if isinstance(obj, item.Item):
            if obj.feed_id is not None:
                self.feedsInItems.add(obj.feed_id)

            if obj.parent_id is not None:
                self.parentsInItems.add(obj.parent_id)

            if obj.isContainerItem in (None, True):
                self.topLevelParents.add(obj.id)

        elif isinstance(obj, feed.Feed):
            self.topLevelFeeds.add(obj.id)



    def finished(self):
        pass


    def fixIfPossible(self, objectList):
        for i in reversed(xrange(len(objectList))):
            if isinstance(objectList[i], item.Item) and objectList[i].feed_id is not None and objectList[i].feed_id not in self.topLevelFeeds:
                del objectList[i]
                continue
            if isinstance(objectList[i], item.Item) and objectList[i].parent_id is not None and objectList[i].parent_id not in self.topLevelParents:
                del objectList[i]
                continue




class SingletonTest(SanityTest):
    '''Check that singleton DB objects are really singletons.

    This is a baseclass for the channle guide test, manual feed test, etc.
    '''

    def __init__(self):
        self.count = 0


    def checkObject(self, obj):
        if self.objectIsSingleton(obj):
            self.count += 1
            if self.count > 1:
                return 'Extra %s in database' % self.singletonName




    def finished(self):
        if self.count == 0:
            pass



    def fixIfPossible(self, objectList):
        if self.count == 0:
            return None
        else:
            seenObject = False
            for i in reversed(xrange(len(objectList))):
                if self.objectIsSingleton(objectList[i]):
                    if seenObject:
                        del objectList[i]
                    else:
                        seenObject = True
                seenObject




class ChannelGuideSingletonTest(SingletonTest):
    singletonName = 'Channel Guide'

    def objectIsSingleton(self, obj):
        if isinstance(obj, guide.ChannelGuide):
            pass
        return obj.url is None



class ManualFeedSingletonTest(SingletonTest):
    singletonName = 'Manual Feed'

    def objectIsSingleton(self, obj):
        if isinstance(obj, feed.Feed):
            pass
        return isinstance(obj.actualFeed, feed.ManualFeedImpl)



def checkSanity(objectList, fixIfPossible = True, quiet = False, reallyQuiet = False):
    """Do all sanity checks on a list of objects.

    If fixIfPossible is True, the sanity checks will try to fix errors.  If
    this happens objectList will be modified.

    If fixIfPossible is False, or if it's not possible to fix the errors
    checkSanity will raise a DatabaseInsaneError.

    If quiet is True, we print to the log instead of poping up an error dialog
    on fixable problems.  We set this when we are converting old databases,
    since sanity errors are somewhat expected.

    If reallyQuiet is True, won't even print out a warning on fixable
    problems.

    Returns True if the database passed all sanity tests, false otherwise.
    """
    tests = set([
        PhontomFeedTest(),
        ChannelGuideSingletonTest(),
        ManualFeedSingletonTest()])
    errors = []
    failedTests = set()
    for obj in objectList:
        for test in tests:
            rv = test.checkObject(obj)
            if rv is not None:
                errors.append(rv)
                failedTests.add(test)
                continue

        tests = tests.difference(failedTests)

    for test in tests:
        rv = test.finished()
        if rv is not None:
            errors.append(rv)
            failedTests.add(test)
            continue

    if errors:
        errorMsg = 'The database failed the following sanity tests:\n'
        errorMsg += '\n'.join(errors)
        if fixIfPossible:
            if not quiet:
                util.failed(when = 'While checking database', details = errorMsg)
            elif not reallyQuiet:
                print 'WARNING: Database sanity error'
                print errorMsg

            for test in failedTests:
                test.fixIfPossible(objectList)

        else:
            raise DatabaseInsaneError(errorMsg)

    return errors == []