ZODB: find oids of objects referencing a specific oid

zodb_refmap.py

from ZODB.serialize import referencesf
from ZODB.FileStorage import FileStorage


def build_refmap(filename):
    """Build a refmap from a filestorage. Look in every record of every
       transaction. Build a dict of oid -> list(referenced oids)
    """
    refmap = {}
    fs = FileStorage(filename, read_only=1)
    fsi = fs.iterator()
    for txn in fsi:
        for rec in txn:
            pickle, revid = fs.load(rec.oid, rec.version)
            refs = referencesf(pickle)
            refmap[rec.oid] = refs
    return refmap


def backrefs(target, refmap):
    """Return a list of oids in the refmap who reference target.
    """
    oidlist = []
    for oid, refs in refmap.iteritems():
        if target in refs:
            oidlist.append(oid)
    return oidlist


def obj_path(target, refmap):
    """For a target oid find the path of objects that refer to it.
       break if we reach no more references or find a cycle
    """
    path = [target]
    additionals = []
    while True:
        target = path[-1:].pop()
        brefs = backrefs(target, refmap)
        if not brefs:
            break
        bref = brefs[0]
        if bref in path:
            print 'cyclic', bref
            break
        if len(brefs) == 1:
            path.append(bref)
            print bref
            continue
        additionals.append((target, brefs[1:]))
        print bref, brefs[1:]
        path.append(bref)
    return (path, additionals)