Mercurial > hg
view mercurial/hgweb/common.py @ 29322:66dbdd3cc2b9 stable
bdiff: extend matches across popular lines
For very large diffs that have large numbers of identical lines (JSON
dumps) that also have large blocks of identical text, bdiff could become
confused about which block matches which because it can only match
very limited regions. The result is very large diffs for small sets of edits.
The earlier recursion rebalancing fix made this behavior more frequent because
it's now more prone to match block 1 to block 2. One frequent user of
large JSON files reported being unable to pass the resulting diffs
through their code review system.
Prior to this change, bdiff would calculate the length of a match at
(i, j) as 1 + length found at (i-1, j-1). With large number of popular
(ignored) lines, this often meant matches couldn't be extended
backwards at all and thus all matching regions were very small.
Disabling the popularity threshold is not an option because it brings
back quadratic behavior.
Instead, we extend a match backwards until we either found a previously
discovered match or we find a mismatching line. This thus successfully
bridges over any popular lines inside and before a matching region.
The larger regions then significant reduce the probability of confusion.
author | Matt Mackall <mpm@selenic.com> |
---|---|
date | Thu, 02 Jun 2016 17:09:06 -0500 |
parents | 37fcfe52c68c |
children | 7f0498bd284e |
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# hgweb/common.py - Utility functions needed by hgweb_mod and hgwebdir_mod # # Copyright 21 May 2005 - (c) 2005 Jake Edge <jake@edge2.net> # Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import import BaseHTTPServer import errno import mimetypes import os HTTP_OK = 200 HTTP_NOT_MODIFIED = 304 HTTP_BAD_REQUEST = 400 HTTP_UNAUTHORIZED = 401 HTTP_FORBIDDEN = 403 HTTP_NOT_FOUND = 404 HTTP_METHOD_NOT_ALLOWED = 405 HTTP_SERVER_ERROR = 500 def ismember(ui, username, userlist): """Check if username is a member of userlist. If userlist has a single '*' member, all users are considered members. Can be overridden by extensions to provide more complex authorization schemes. """ return userlist == ['*'] or username in userlist def checkauthz(hgweb, req, op): '''Check permission for operation based on request data (including authentication info). Return if op allowed, else raise an ErrorResponse exception.''' user = req.env.get('REMOTE_USER') deny_read = hgweb.configlist('web', 'deny_read') if deny_read and (not user or ismember(hgweb.repo.ui, user, deny_read)): raise ErrorResponse(HTTP_UNAUTHORIZED, 'read not authorized') allow_read = hgweb.configlist('web', 'allow_read') if allow_read and (not ismember(hgweb.repo.ui, user, allow_read)): raise ErrorResponse(HTTP_UNAUTHORIZED, 'read not authorized') if op == 'pull' and not hgweb.allowpull: raise ErrorResponse(HTTP_UNAUTHORIZED, 'pull not authorized') elif op == 'pull' or op is None: # op is None for interface requests return # enforce that you can only push using POST requests if req.env['REQUEST_METHOD'] != 'POST': msg = 'push requires POST request' raise ErrorResponse(HTTP_METHOD_NOT_ALLOWED, msg) # require ssl by default for pushing, auth info cannot be sniffed # and replayed scheme = req.env.get('wsgi.url_scheme') if hgweb.configbool('web', 'push_ssl', True) and scheme != 'https': raise ErrorResponse(HTTP_FORBIDDEN, 'ssl required') deny = hgweb.configlist('web', 'deny_push') if deny and (not user or ismember(hgweb.repo.ui, user, deny)): raise ErrorResponse(HTTP_UNAUTHORIZED, 'push not authorized') allow = hgweb.configlist('web', 'allow_push') if not (allow and ismember(hgweb.repo.ui, user, allow)): raise ErrorResponse(HTTP_UNAUTHORIZED, 'push not authorized') # Hooks for hgweb permission checks; extensions can add hooks here. # Each hook is invoked like this: hook(hgweb, request, operation), # where operation is either read, pull or push. Hooks should either # raise an ErrorResponse exception, or just return. # # It is possible to do both authentication and authorization through # this. permhooks = [checkauthz] class ErrorResponse(Exception): def __init__(self, code, message=None, headers=[]): if message is None: message = _statusmessage(code) Exception.__init__(self, message) self.code = code self.headers = headers class continuereader(object): def __init__(self, f, write): self.f = f self._write = write self.continued = False def read(self, amt=-1): if not self.continued: self.continued = True self._write('HTTP/1.1 100 Continue\r\n\r\n') return self.f.read(amt) def __getattr__(self, attr): if attr in ('close', 'readline', 'readlines', '__iter__'): return getattr(self.f, attr) raise AttributeError def _statusmessage(code): responses = BaseHTTPServer.BaseHTTPRequestHandler.responses return responses.get(code, ('Error', 'Unknown error'))[0] def statusmessage(code, message=None): return '%d %s' % (code, message or _statusmessage(code)) def get_stat(spath, fn): """stat fn if it exists, spath otherwise""" cl_path = os.path.join(spath, fn) if os.path.exists(cl_path): return os.stat(cl_path) else: return os.stat(spath) def get_mtime(spath): return get_stat(spath, "00changelog.i").st_mtime def staticfile(directory, fname, req): """return a file inside directory with guessed Content-Type header fname always uses '/' as directory separator and isn't allowed to contain unusual path components. Content-Type is guessed using the mimetypes module. Return an empty string if fname is illegal or file not found. """ parts = fname.split('/') for part in parts: if (part in ('', os.curdir, os.pardir) or os.sep in part or os.altsep is not None and os.altsep in part): return fpath = os.path.join(*parts) if isinstance(directory, str): directory = [directory] for d in directory: path = os.path.join(d, fpath) if os.path.exists(path): break try: os.stat(path) ct = mimetypes.guess_type(path)[0] or "text/plain" fp = open(path, 'rb') data = fp.read() fp.close() req.respond(HTTP_OK, ct, body=data) except TypeError: raise ErrorResponse(HTTP_SERVER_ERROR, 'illegal filename') except OSError as err: if err.errno == errno.ENOENT: raise ErrorResponse(HTTP_NOT_FOUND) else: raise ErrorResponse(HTTP_SERVER_ERROR, err.strerror) def paritygen(stripecount, offset=0): """count parity of horizontal stripes for easier reading""" if stripecount and offset: # account for offset, e.g. due to building the list in reverse count = (stripecount + offset) % stripecount parity = (stripecount + offset) / stripecount & 1 else: count = 0 parity = 0 while True: yield parity count += 1 if stripecount and count >= stripecount: parity = 1 - parity count = 0 def get_contact(config): """Return repo contact information or empty string. web.contact is the primary source, but if that is not set, try ui.username or $EMAIL as a fallback to display something useful. """ return (config("web", "contact") or config("ui", "username") or os.environ.get("EMAIL") or "") def caching(web, req): tag = str(web.mtime) if req.env.get('HTTP_IF_NONE_MATCH') == tag: raise ErrorResponse(HTTP_NOT_MODIFIED) req.headers.append(('ETag', tag))