tests/test-revlog-ancestry.py

revlog: addgroup checks if incoming deltas add censored revs, sets flag bit

A censored revision stored in a revlog should have the censored revlog index
flag bit set. This implies we must know if a revision is censored before we
add it to the revlog. When adding revisions from exchanged deltas, we would
prefer to determine this flag without decoding every single full text.

This change introduces a heuristic based on assumptions around the Mercurial
delta format and filelog metadata. Since deltas which produce a censored
revision must be full-replacement deltas, we can read the delta's first bytes
to check the filelog metadata. Since "censored" is the alphabetically first
filelog metadata key, censored filelog revisions have a well-known prefix we
can look for.

For more on the design and background of the censorship feature, see:
http://mercurial.selenic.com/wiki/CensorPlan

import os
from mercurial import hg, ui, merge

u = ui.ui()

repo = hg.repository(u, 'test1', create=1)
os.chdir('test1')

def commit(text, time):
    repo.commit(text=text, date="%d 0" % time)

def addcommit(name, time):
    f = open(name, 'w')
    f.write('%s\n' % name)
    f.close()
    repo[None].add([name])
    commit(name, time)

def update(rev):
    merge.update(repo, rev, False, True, False)

def merge_(rev):
    merge.update(repo, rev, True, False, False)

if __name__ == '__main__':
    addcommit("A", 0)
    addcommit("B", 1)

    update(0)
    addcommit("C", 2)

    merge_(1)
    commit("D", 3)

    update(2)
    addcommit("E", 4)
    addcommit("F", 5)

    update(3)
    addcommit("G", 6)

    merge_(5)
    commit("H", 7)

    update(5)
    addcommit("I", 8)

    # Ancestors
    print 'Ancestors of 5'
    for r in repo.changelog.ancestors([5]):
        print r,

    print '\nAncestors of 6 and 5'
    for r in repo.changelog.ancestors([6, 5]):
        print r,

    print '\nAncestors of 5 and 4'
    for r in repo.changelog.ancestors([5, 4]):
        print r,

    print '\nAncestors of 7, stop at 6'
    for r in repo.changelog.ancestors([7], 6):
        print r,

    print '\nAncestors of 7, including revs'
    for r in repo.changelog.ancestors([7], inclusive=True):
        print r,

    print '\nAncestors of 7, 5 and 3, including revs'
    for r in repo.changelog.ancestors([7, 5, 3], inclusive=True):
        print r,

    # Descendants
    print '\n\nDescendants of 5'
    for r in repo.changelog.descendants([5]):
        print r,

    print '\nDescendants of 5 and 3'
    for r in repo.changelog.descendants([5, 3]):
        print r,

    print '\nDescendants of 5 and 4'
    for r in repo.changelog.descendants([5, 4]):
        print r,