wireproto: move wireproto capabilities computation in a subfunction

It will help people that need to add capabilities (in a more subtle was that
just adding some to the list) in multiple way:

1. This function returns a list, not a string. Making it easier to look at,
   extend or alter the content.

2. The original capabilities function will be store in the dictionary of wire
   protocol command. So extension that wrap this function also need to update
   the dictionary entry.

   Both wrapping and update of the dictionary entry are needed because the
   `hello` wire protocol use the function itself. This is specifically sneaky for
   extension writer as ssh use the `hello` command while http use the
   `capabilities` command.

   With this new `_capabilities` function there is one and only one obvious
   place to wrap when needed.

mercurial/wireproto.py

@@ -1,665 +1,680
 # wireproto.py - generic wire protocol support functions
 #
 # Copyright 2005-2010 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 import urllib, tempfile, os, sys
 from i18n import _
 from node import bin, hex
 import changegroup as changegroupmod
 import peer, error, encoding, util, store
 
 # abstract batching support
 
 class future(object):
     '''placeholder for a value to be set later'''
     def set(self, value):
         if util.safehasattr(self, 'value'):
             raise error.RepoError("future is already set")
         self.value = value
 
 class batcher(object):
     '''base class for batches of commands submittable in a single request
 
     All methods invoked on instances of this class are simply queued and
     return a a future for the result. Once you call submit(), all the queued
     calls are performed and the results set in their respective futures.
     '''
     def __init__(self):
         self.calls = []
     def __getattr__(self, name):
         def call(*args, **opts):
             resref = future()
             self.calls.append((name, args, opts, resref,))
             return resref
         return call
     def submit(self):
         pass
 
 class localbatch(batcher):
     '''performs the queued calls directly'''
     def __init__(self, local):
         batcher.__init__(self)
         self.local = local
     def submit(self):
         for name, args, opts, resref in self.calls:
             resref.set(getattr(self.local, name)(*args, **opts))
 
 class remotebatch(batcher):
     '''batches the queued calls; uses as few roundtrips as possible'''
     def __init__(self, remote):
         '''remote must support _submitbatch(encbatch) and
         _submitone(op, encargs)'''
         batcher.__init__(self)
         self.remote = remote
     def submit(self):
         req, rsp = [], []
         for name, args, opts, resref in self.calls:
             mtd = getattr(self.remote, name)
             batchablefn = getattr(mtd, 'batchable', None)
             if batchablefn is not None:
                 batchable = batchablefn(mtd.im_self, *args, **opts)
                 encargsorres, encresref = batchable.next()
                 if encresref:
                     req.append((name, encargsorres,))
                     rsp.append((batchable, encresref, resref,))
                 else:
                     resref.set(encargsorres)
             else:
                 if req:
                     self._submitreq(req, rsp)
                     req, rsp = [], []
                 resref.set(mtd(*args, **opts))
         if req:
             self._submitreq(req, rsp)
     def _submitreq(self, req, rsp):
         encresults = self.remote._submitbatch(req)
         for encres, r in zip(encresults, rsp):
             batchable, encresref, resref = r
             encresref.set(encres)
             resref.set(batchable.next())
 
 def batchable(f):
     '''annotation for batchable methods
 
     Such methods must implement a coroutine as follows:
 
     @batchable
     def sample(self, one, two=None):
         # Handle locally computable results first:
         if not one:
             yield "a local result", None
         # Build list of encoded arguments suitable for your wire protocol:
         encargs = [('one', encode(one),), ('two', encode(two),)]
         # Create future for injection of encoded result:
         encresref = future()
         # Return encoded arguments and future:
         yield encargs, encresref
         # Assuming the future to be filled with the result from the batched
         # request now. Decode it:
         yield decode(encresref.value)
 
     The decorator returns a function which wraps this coroutine as a plain
     method, but adds the original method as an attribute called "batchable",
     which is used by remotebatch to split the call into separate encoding and
     decoding phases.
     '''
     def plain(*args, **opts):
         batchable = f(*args, **opts)
         encargsorres, encresref = batchable.next()
         if not encresref:
             return encargsorres # a local result in this case
         self = args[0]
         encresref.set(self._submitone(f.func_name, encargsorres))
         return batchable.next()
     setattr(plain, 'batchable', f)
     return plain
 
 # list of nodes encoding / decoding
 
 def decodelist(l, sep=' '):
     if l:
         return map(bin, l.split(sep))
     return []
 
 def encodelist(l, sep=' '):
     return sep.join(map(hex, l))
 
 # batched call argument encoding
 
 def escapearg(plain):
     return (plain
             .replace(':', '::')
             .replace(',', ':,')
             .replace(';', ':;')
             .replace('=', ':='))
 
 def unescapearg(escaped):
     return (escaped
             .replace(':=', '=')
             .replace(':;', ';')
             .replace(':,', ',')
             .replace('::', ':'))
 
 # client side
 
 class wirepeer(peer.peerrepository):
 
     def batch(self):
         return remotebatch(self)
     def _submitbatch(self, req):
         cmds = []
         for op, argsdict in req:
             args = ','.join('%s=%s' % p for p in argsdict.iteritems())
             cmds.append('%s %s' % (op, args))
         rsp = self._call("batch", cmds=';'.join(cmds))
         return rsp.split(';')
     def _submitone(self, op, args):
         return self._call(op, **args)
 
     @batchable
     def lookup(self, key):
         self.requirecap('lookup', _('look up remote revision'))
         f = future()
         yield {'key': encoding.fromlocal(key)}, f
         d = f.value
         success, data = d[:-1].split(" ", 1)
         if int(success):
             yield bin(data)
         self._abort(error.RepoError(data))
 
     @batchable
     def heads(self):
         f = future()
         yield {}, f
         d = f.value
         try:
             yield decodelist(d[:-1])
         except ValueError:
             self._abort(error.ResponseError(_("unexpected response:"), d))
 
     @batchable
     def known(self, nodes):
         f = future()
         yield {'nodes': encodelist(nodes)}, f
         d = f.value
         try:
             yield [bool(int(f)) for f in d]
         except ValueError:
             self._abort(error.ResponseError(_("unexpected response:"), d))
 
     @batchable
     def branchmap(self):
         f = future()
         yield {}, f
         d = f.value
         try:
             branchmap = {}
             for branchpart in d.splitlines():
                 branchname, branchheads = branchpart.split(' ', 1)
                 branchname = encoding.tolocal(urllib.unquote(branchname))
                 branchheads = decodelist(branchheads)
                 branchmap[branchname] = branchheads
             yield branchmap
         except TypeError:
             self._abort(error.ResponseError(_("unexpected response:"), d))
 
     def branches(self, nodes):
         n = encodelist(nodes)
         d = self._call("branches", nodes=n)
         try:
             br = [tuple(decodelist(b)) for b in d.splitlines()]
             return br
         except ValueError:
             self._abort(error.ResponseError(_("unexpected response:"), d))
 
     def between(self, pairs):
         batch = 8 # avoid giant requests
         r = []
         for i in xrange(0, len(pairs), batch):
             n = " ".join([encodelist(p, '-') for p in pairs[i:i + batch]])
             d = self._call("between", pairs=n)
             try:
                 r.extend(l and decodelist(l) or [] for l in d.splitlines())
             except ValueError:
                 self._abort(error.ResponseError(_("unexpected response:"), d))
         return r
 
     @batchable
     def pushkey(self, namespace, key, old, new):
         if not self.capable('pushkey'):
             yield False, None
         f = future()
         self.ui.debug('preparing pushkey for "%s:%s"\n' % (namespace, key))
         yield {'namespace': encoding.fromlocal(namespace),
                'key': encoding.fromlocal(key),
                'old': encoding.fromlocal(old),
                'new': encoding.fromlocal(new)}, f
         d = f.value
         d, output = d.split('\n', 1)
         try:
             d = bool(int(d))
         except ValueError:
             raise error.ResponseError(
                 _('push failed (unexpected response):'), d)
         for l in output.splitlines(True):
             self.ui.status(_('remote: '), l)
         yield d
 
     @batchable
     def listkeys(self, namespace):
         if not self.capable('pushkey'):
             yield {}, None
         f = future()
         self.ui.debug('preparing listkeys for "%s"\n' % namespace)
         yield {'namespace': encoding.fromlocal(namespace)}, f
         d = f.value
         r = {}
         for l in d.splitlines():
             k, v = l.split('\t')
             r[encoding.tolocal(k)] = encoding.tolocal(v)
         yield r
 
     def stream_out(self):
         return self._callstream('stream_out')
 
     def changegroup(self, nodes, kind):
         n = encodelist(nodes)
         f = self._callstream("changegroup", roots=n)
         return changegroupmod.unbundle10(self._decompress(f), 'UN')
 
     def changegroupsubset(self, bases, heads, kind):
         self.requirecap('changegroupsubset', _('look up remote changes'))
         bases = encodelist(bases)
         heads = encodelist(heads)
         f = self._callstream("changegroupsubset",
                              bases=bases, heads=heads)
         return changegroupmod.unbundle10(self._decompress(f), 'UN')
 
     def getbundle(self, source, heads=None, common=None, bundlecaps=None):
         self.requirecap('getbundle', _('look up remote changes'))
         opts = {}
         if heads is not None:
             opts['heads'] = encodelist(heads)
         if common is not None:
             opts['common'] = encodelist(common)
         if bundlecaps is not None:
             opts['bundlecaps'] = ','.join(bundlecaps)
         f = self._callstream("getbundle", **opts)
         return changegroupmod.unbundle10(self._decompress(f), 'UN')
 
     def unbundle(self, cg, heads, source):
         '''Send cg (a readable file-like object representing the
         changegroup to push, typically a chunkbuffer object) to the
         remote server as a bundle. Return an integer indicating the
         result of the push (see localrepository.addchangegroup()).'''
 
         if heads != ['force'] and self.capable('unbundlehash'):
             heads = encodelist(['hashed',
                                 util.sha1(''.join(sorted(heads))).digest()])
         else:
             heads = encodelist(heads)
 
         ret, output = self._callpush("unbundle", cg, heads=heads)
         if ret == "":
             raise error.ResponseError(
                 _('push failed:'), output)
         try:
             ret = int(ret)
         except ValueError:
             raise error.ResponseError(
                 _('push failed (unexpected response):'), ret)
 
         for l in output.splitlines(True):
             self.ui.status(_('remote: '), l)
         return ret
 
     def debugwireargs(self, one, two, three=None, four=None, five=None):
         # don't pass optional arguments left at their default value
         opts = {}
         if three is not None:
             opts['three'] = three
         if four is not None:
             opts['four'] = four
         return self._call('debugwireargs', one=one, two=two, **opts)
 
 # server side
 
 class streamres(object):
     def __init__(self, gen):
         self.gen = gen
 
 class pushres(object):
     def __init__(self, res):
         self.res = res
 
 class pusherr(object):
     def __init__(self, res):
         self.res = res
 
 class ooberror(object):
     def __init__(self, message):
         self.message = message
 
 def dispatch(repo, proto, command):
     repo = repo.filtered("served")
     func, spec = commands[command]
     args = proto.getargs(spec)
     return func(repo, proto, *args)
 
 def options(cmd, keys, others):
     opts = {}
     for k in keys:
         if k in others:
             opts[k] = others[k]
             del others[k]
     if others:
         sys.stderr.write("abort: %s got unexpected arguments %s\n"
                          % (cmd, ",".join(others)))
     return opts
 
 def batch(repo, proto, cmds, others):
     repo = repo.filtered("served")
     res = []
     for pair in cmds.split(';'):
         op, args = pair.split(' ', 1)
         vals = {}
         for a in args.split(','):
             if a:
                 n, v = a.split('=')
                 vals[n] = unescapearg(v)
         func, spec = commands[op]
         if spec:
             keys = spec.split()
             data = {}
             for k in keys:
                 if k == '*':
                     star = {}
                     for key in vals.keys():
                         if key not in keys:
                             star[key] = vals[key]
                     data['*'] = star
                 else:
                     data[k] = vals[k]
             result = func(repo, proto, *[data[k] for k in keys])
         else:
             result = func(repo, proto)
         if isinstance(result, ooberror):
             return result
         res.append(escapearg(result))
     return ';'.join(res)
 
 def between(repo, proto, pairs):
     pairs = [decodelist(p, '-') for p in pairs.split(" ")]
     r = []
     for b in repo.between(pairs):
         r.append(encodelist(b) + "\n")
     return "".join(r)
 
 def branchmap(repo, proto):
     branchmap = repo.branchmap()
     heads = []
     for branch, nodes in branchmap.iteritems():
         branchname = urllib.quote(encoding.fromlocal(branch))
         branchnodes = encodelist(nodes)
         heads.append('%s %s' % (branchname, branchnodes))
     return '\n'.join(heads)
 
 def branches(repo, proto, nodes):
     nodes = decodelist(nodes)
     r = []
     for b in repo.branches(nodes):
         r.append(encodelist(b) + "\n")
     return "".join(r)
 
 
 wireprotocaps = ['lookup', 'changegroupsubset', 'branchmap', 'pushkey',
                  'known', 'getbundle', 'unbundlehash', 'batch']
-def capabilities(repo, proto):
+
+def _capabilities(repo, proto):
+    """return a list of capabilities for a repo
+
+    This function exists to allow extensions to easily wrap capabilities
+    computation
+
+    - returns a lists: easy to alter
+    - change done here will be propagated to both `capabilities` and `hello`
+      command without any other effort. without any other action needed.
+    """
     # copy to prevent modification of the global list
     caps = list(wireprotocaps)
     if _allowstream(repo.ui):
         if repo.ui.configbool('server', 'preferuncompressed', False):
             caps.append('stream-preferred')
         requiredformats = repo.requirements & repo.supportedformats
         # if our local revlogs are just revlogv1, add 'stream' cap
         if not requiredformats - set(('revlogv1',)):
             caps.append('stream')
         # otherwise, add 'streamreqs' detailing our local revlog format
         else:
             caps.append('streamreqs=%s' % ','.join(requiredformats))
     caps.append('unbundle=%s' % ','.join(changegroupmod.bundlepriority))
     caps.append('httpheader=1024')
-    return ' '.join(caps)
+    return caps
+
+# If you are writting and extension and consider wrapping this function. Wrap
+# `_capabilities` instead.
+def capabilities(repo, proto):
+    return ' '.join(_capabilities(repo, proto))
 
 def changegroup(repo, proto, roots):
     nodes = decodelist(roots)
     cg = repo.changegroup(nodes, 'serve')
     return streamres(proto.groupchunks(cg))
 
 def changegroupsubset(repo, proto, bases, heads):
     bases = decodelist(bases)
     heads = decodelist(heads)
     cg = repo.changegroupsubset(bases, heads, 'serve')
     return streamres(proto.groupchunks(cg))
 
 def debugwireargs(repo, proto, one, two, others):
     # only accept optional args from the known set
     opts = options('debugwireargs', ['three', 'four'], others)
     return repo.debugwireargs(one, two, **opts)
 
 def getbundle(repo, proto, others):
     opts = options('getbundle', ['heads', 'common', 'bundlecaps'], others)
     for k, v in opts.iteritems():
         if k in ('heads', 'common'):
             opts[k] = decodelist(v)
         elif k == 'bundlecaps':
             opts[k] = set(v.split(','))
     cg = repo.getbundle('serve', **opts)
     return streamres(proto.groupchunks(cg))
 
 def heads(repo, proto):
     h = repo.heads()
     return encodelist(h) + "\n"
 
 def hello(repo, proto):
     '''the hello command returns a set of lines describing various
     interesting things about the server, in an RFC822-like format.
     Currently the only one defined is "capabilities", which
     consists of a line in the form:
 
     capabilities: space separated list of tokens
     '''
     return "capabilities: %s\n" % (capabilities(repo, proto))
 
 def listkeys(repo, proto, namespace):
     d = repo.listkeys(encoding.tolocal(namespace)).items()
     t = '\n'.join(['%s\t%s' % (encoding.fromlocal(k), encoding.fromlocal(v))
                    for k, v in d])
     return t
 
 def lookup(repo, proto, key):
     try:
         k = encoding.tolocal(key)
         c = repo[k]
         r = c.hex()
         success = 1
     except Exception, inst:
         r = str(inst)
         success = 0
     return "%s %s\n" % (success, r)
 
 def known(repo, proto, nodes, others):
     return ''.join(b and "1" or "0" for b in repo.known(decodelist(nodes)))
 
 def pushkey(repo, proto, namespace, key, old, new):
     # compatibility with pre-1.8 clients which were accidentally
     # sending raw binary nodes rather than utf-8-encoded hex
     if len(new) == 20 and new.encode('string-escape') != new:
         # looks like it could be a binary node
         try:
             new.decode('utf-8')
             new = encoding.tolocal(new) # but cleanly decodes as UTF-8
         except UnicodeDecodeError:
             pass # binary, leave unmodified
     else:
         new = encoding.tolocal(new) # normal path
 
     if util.safehasattr(proto, 'restore'):
 
         proto.redirect()
 
         try:
             r = repo.pushkey(encoding.tolocal(namespace), encoding.tolocal(key),
                              encoding.tolocal(old), new) or False
         except util.Abort:
             r = False
 
         output = proto.restore()
 
         return '%s\n%s' % (int(r), output)
 
     r = repo.pushkey(encoding.tolocal(namespace), encoding.tolocal(key),
                      encoding.tolocal(old), new)
     return '%s\n' % int(r)
 
 def _allowstream(ui):
     return ui.configbool('server', 'uncompressed', True, untrusted=True)
 
 def _walkstreamfiles(repo):
     # this is it's own function so extensions can override it
     return repo.store.walk()
 
 def stream(repo, proto):
     '''If the server supports streaming clone, it advertises the "stream"
     capability with a value representing the version and flags of the repo
     it is serving. Client checks to see if it understands the format.
 
     The format is simple: the server writes out a line with the amount
     of files, then the total amount of bytes to be transferred (separated
     by a space). Then, for each file, the server first writes the filename
     and filesize (separated by the null character), then the file contents.
     '''
 
     if not _allowstream(repo.ui):
         return '1\n'
 
     entries = []
     total_bytes = 0
     try:
         # get consistent snapshot of repo, lock during scan
         lock = repo.lock()
         try:
             repo.ui.debug('scanning\n')
             for name, ename, size in _walkstreamfiles(repo):
                 if size:
                     entries.append((name, size))
                     total_bytes += size
         finally:
             lock.release()
     except error.LockError:
         return '2\n' # error: 2
 
     def streamer(repo, entries, total):
         '''stream out all metadata files in repository.'''
         yield '0\n' # success
         repo.ui.debug('%d files, %d bytes to transfer\n' %
                       (len(entries), total_bytes))
         yield '%d %d\n' % (len(entries), total_bytes)
 
         sopener = repo.sopener
         oldaudit = sopener.mustaudit
         debugflag = repo.ui.debugflag
         sopener.mustaudit = False
 
         try:
             for name, size in entries:
                 if debugflag:
                     repo.ui.debug('sending %s (%d bytes)\n' % (name, size))
                 # partially encode name over the wire for backwards compat
                 yield '%s\0%d\n' % (store.encodedir(name), size)
                 if size <= 65536:
                     fp = sopener(name)
                     try:
                         data = fp.read(size)
                     finally:
                         fp.close()
                     yield data
                 else:
                     for chunk in util.filechunkiter(sopener(name), limit=size):
                         yield chunk
         # replace with "finally:" when support for python 2.4 has been dropped
         except Exception:
             sopener.mustaudit = oldaudit
             raise
         sopener.mustaudit = oldaudit
 
     return streamres(streamer(repo, entries, total_bytes))
 
 def unbundle(repo, proto, heads):
     their_heads = decodelist(heads)
 
     def check_heads():
         heads = repo.heads()
         heads_hash = util.sha1(''.join(sorted(heads))).digest()
         return (their_heads == ['force'] or their_heads == heads or
                 their_heads == ['hashed', heads_hash])
 
     proto.redirect()
 
     # fail early if possible
     if not check_heads():
         return pusherr('repository changed while preparing changes - '
                        'please try again')
 
     # write bundle data to temporary file because it can be big
     fd, tempname = tempfile.mkstemp(prefix='hg-unbundle-')
     fp = os.fdopen(fd, 'wb+')
     r = 0
     try:
         proto.getfile(fp)
         lock = repo.lock()
         try:
             if not check_heads():
                 # someone else committed/pushed/unbundled while we
                 # were transferring data
                 return pusherr('repository changed while uploading changes - '
                                'please try again')
 
             # push can proceed
             fp.seek(0)
             gen = changegroupmod.readbundle(fp, None)
 
             try:
                 r = repo.addchangegroup(gen, 'serve', proto._client())
             except util.Abort, inst:
                 sys.stderr.write("abort: %s\n" % inst)
         finally:
             lock.release()
         return pushres(r)
 
     finally:
         fp.close()
         os.unlink(tempname)
 
 commands = {
     'batch': (batch, 'cmds *'),
     'between': (between, 'pairs'),
     'branchmap': (branchmap, ''),
     'branches': (branches, 'nodes'),
     'capabilities': (capabilities, ''),
     'changegroup': (changegroup, 'roots'),
     'changegroupsubset': (changegroupsubset, 'bases heads'),
     'debugwireargs': (debugwireargs, 'one two *'),
     'getbundle': (getbundle, '*'),
     'heads': (heads, ''),
     'hello': (hello, ''),
     'known': (known, 'nodes *'),
     'listkeys': (listkeys, 'namespace'),
     'lookup': (lookup, 'key'),
     'pushkey': (pushkey, 'namespace key old new'),
     'stream_out': (stream, ''),
     'unbundle': (unbundle, 'heads'),
 }