Mercurial > hg
view tests/svnxml.py @ 17970:0b03454abae7
ancestor: faster algorithm for difference of ancestor sets
One of the major reasons rebase is slow in large repositories is
the computation of the detach set: the set of ancestors of the
changesets to rebase not in the destination parent. This is currently
done via a revset that does two walks all the way to the root of
the DAG. Instead of doing that, to find ancestors of a set <revs>
not in another set <common> we walk up the tree in reverse revision
number order, maintaining sets of nodes visited from <revs>, <common>
or both.
For the common case where the sets are close both topologically and
in revision number (relative to repository size), this has been
found to speed up rebase by around 15-20%. When the nodes are farther
apart and the DAG is highly branching, it is harder to say which
would win.
Here's how long computing the detach set takes in a linear repository
with over 400000 changesets, rebasing near tip:
Rebasing across 4 changesets
Revset method: 2.2s
New algorithm: 0.00015s
Rebasing across 250 changesets
Revset method: 2.2s
New algorithm: 0.00069s
Rebasing across 10000 changesets
Revset method: 2.4s
New algorithm: 0.019s
author | Siddharth Agarwal <sid0@fb.com> |
---|---|
date | Mon, 26 Nov 2012 11:46:51 -0800 |
parents | c58bdecdb800 |
children | 812eb3b7dc43 |
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# Read the output of a "svn log --xml" command on stdin, parse it and # print a subset of attributes common to all svn versions tested by # hg. import xml.dom.minidom, sys def xmltext(e): return ''.join(c.data for c in e.childNodes if c.nodeType == c.TEXT_NODE) def parseentry(entry): e = {} e['revision'] = entry.getAttribute('revision') e['author'] = xmltext(entry.getElementsByTagName('author')[0]) e['msg'] = xmltext(entry.getElementsByTagName('msg')[0]) e['paths'] = [] paths = entry.getElementsByTagName('paths') if paths: paths = paths[0] for p in paths.getElementsByTagName('path'): action = p.getAttribute('action') path = xmltext(p) frompath = p.getAttribute('copyfrom-path') fromrev = p.getAttribute('copyfrom-rev') e['paths'].append((path, action, frompath, fromrev)) return e def parselog(data): entries = [] doc = xml.dom.minidom.parseString(data) for e in doc.getElementsByTagName('logentry'): entries.append(parseentry(e)) return entries def printentries(entries): fp = sys.stdout for e in entries: for k in ('revision', 'author', 'msg'): fp.write(('%s: %s\n' % (k, e[k])).encode('utf-8')) for path, action, fpath, frev in sorted(e['paths']): frominfo = '' if frev: frominfo = ' (from %s@%s)' % (fpath, frev) p = ' %s %s%s\n' % (action, path, frominfo) fp.write(p.encode('utf-8')) if __name__ == '__main__': data = sys.stdin.read() entries = parselog(data) printentries(entries)