Mercurial > hg
view mercurial/streamclone.py @ 29304:5e32852fa4bd
revset: make filteredset.__nonzero__ respect the order of the filteredset
This fix allows __nonzero__ to respect the direction of iteration of the
whole filteredset. Here's the case when it matters. Imagine that we have a
very large repository and we want to execute a command like:
$ hg log --rev '(tip:0) and user(ikostia)' --limit 1
(we want to get the latest commit by me).
Mercurial will evaluate a filteredset lazy data structure, an
instance of the filteredset class, which will know that it has to iterate
in a descending order (isdescending() will return True if called). This
means that when some code iterates over the instance of this filteredset,
the 'and user(ikostia)' condition will be first checked on the latest
revision, then on the second latest and so on, allowing Mercurial to
print matches as it founds them. However, cmdutil.getgraphlogrevs
contains the following code:
revs = _logrevs(repo, opts)
if not revs:
return revset.baseset(), None, None
The "not revs" expression is evaluated by calling filteredset.__nonzero__,
which in its current implementation will try to iterate the filteredset
in ascending order until it finds a revision that matches the 'and user(..'
condition. If the condition is only true on late revisions, a lot of
useless iterations will be done. These iterations could be avoided if
__nonzero__ followed the order of the filteredset, which in my opinion
is a sensible thing to do here.
The problem gets even worse when instead of 'user(ikostia)' some more
expensive check is performed, like grepping the commit diff.
I tested this fix on a very large repo where tip is my commit and my very
first commit comes fairly late in the revision history. Results of timing
of the above command on that very large repo.
-with my fix:
real 0m1.795s
user 0m1.657s
sys 0m0.135s
-without my fix:
real 1m29.245s
user 1m28.223s
sys 0m0.929s
I understand that this is a very specific kind of problem that presents
itself very rarely, only on very big repositories and with expensive
checks and so on. But I don't see any disadvantages to this kind of fix
either.
author | Kostia Balytskyi <ikostia@fb.com> |
---|---|
date | Thu, 02 Jun 2016 22:39:01 +0100 |
parents | ed75909c4c67 |
children | f32f8bf5dc4c |
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# streamclone.py - producing and consuming streaming repository data # # Copyright 2015 Gregory Szorc <gregory.szorc@gmail.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 struct import time from .i18n import _ from . import ( branchmap, error, store, util, ) def canperformstreamclone(pullop, bailifbundle2supported=False): """Whether it is possible to perform a streaming clone as part of pull. ``bailifbundle2supported`` will cause the function to return False if bundle2 stream clones are supported. It should only be called by the legacy stream clone code path. Returns a tuple of (supported, requirements). ``supported`` is True if streaming clone is supported and False otherwise. ``requirements`` is a set of repo requirements from the remote, or ``None`` if stream clone isn't supported. """ repo = pullop.repo remote = pullop.remote bundle2supported = False if pullop.canusebundle2: if 'v1' in pullop.remotebundle2caps.get('stream', []): bundle2supported = True # else # Server doesn't support bundle2 stream clone or doesn't support # the versions we support. Fall back and possibly allow legacy. # Ensures legacy code path uses available bundle2. if bailifbundle2supported and bundle2supported: return False, None # Ensures bundle2 doesn't try to do a stream clone if it isn't supported. #elif not bailifbundle2supported and not bundle2supported: # return False, None # Streaming clone only works on empty repositories. if len(repo): return False, None # Streaming clone only works if all data is being requested. if pullop.heads: return False, None streamrequested = pullop.streamclonerequested # If we don't have a preference, let the server decide for us. This # likely only comes into play in LANs. if streamrequested is None: # The server can advertise whether to prefer streaming clone. streamrequested = remote.capable('stream-preferred') if not streamrequested: return False, None # In order for stream clone to work, the client has to support all the # requirements advertised by the server. # # The server advertises its requirements via the "stream" and "streamreqs" # capability. "stream" (a value-less capability) is advertised if and only # if the only requirement is "revlogv1." Else, the "streamreqs" capability # is advertised and contains a comma-delimited list of requirements. requirements = set() if remote.capable('stream'): requirements.add('revlogv1') else: streamreqs = remote.capable('streamreqs') # This is weird and shouldn't happen with modern servers. if not streamreqs: return False, None streamreqs = set(streamreqs.split(',')) # Server requires something we don't support. Bail. if streamreqs - repo.supportedformats: return False, None requirements = streamreqs return True, requirements def maybeperformlegacystreamclone(pullop): """Possibly perform a legacy stream clone operation. Legacy stream clones are performed as part of pull but before all other operations. A legacy stream clone will not be performed if a bundle2 stream clone is supported. """ supported, requirements = canperformstreamclone(pullop) if not supported: return repo = pullop.repo remote = pullop.remote # Save remote branchmap. We will use it later to speed up branchcache # creation. rbranchmap = None if remote.capable('branchmap'): rbranchmap = remote.branchmap() repo.ui.status(_('streaming all changes\n')) fp = remote.stream_out() l = fp.readline() try: resp = int(l) except ValueError: raise error.ResponseError( _('unexpected response from remote server:'), l) if resp == 1: raise error.Abort(_('operation forbidden by server')) elif resp == 2: raise error.Abort(_('locking the remote repository failed')) elif resp != 0: raise error.Abort(_('the server sent an unknown error code')) l = fp.readline() try: filecount, bytecount = map(int, l.split(' ', 1)) except (ValueError, TypeError): raise error.ResponseError( _('unexpected response from remote server:'), l) with repo.lock(): consumev1(repo, fp, filecount, bytecount) # new requirements = old non-format requirements + # new format-related remote requirements # requirements from the streamed-in repository repo.requirements = requirements | ( repo.requirements - repo.supportedformats) repo._applyopenerreqs() repo._writerequirements() if rbranchmap: branchmap.replacecache(repo, rbranchmap) repo.invalidate() def allowservergeneration(ui): """Whether streaming clones are allowed from the server.""" return ui.configbool('server', 'uncompressed', True, untrusted=True) # This is it's own function so extensions can override it. def _walkstreamfiles(repo): return repo.store.walk() def generatev1(repo): """Emit content for version 1 of a streaming clone. This returns a 3-tuple of (file count, byte size, data iterator). The data iterator consists of N entries for each file being transferred. Each file entry starts as a line with the file name and integer size delimited by a null byte. The raw file data follows. Following the raw file data is the next file entry, or EOF. When used on the wire protocol, an additional line indicating protocol success will be prepended to the stream. This function is not responsible for adding it. This function will obtain a repository lock to ensure a consistent view of the store is captured. It therefore may raise LockError. """ entries = [] total_bytes = 0 # Get consistent snapshot of repo, lock during scan. with repo.lock(): repo.ui.debug('scanning\n') for name, ename, size in _walkstreamfiles(repo): if size: entries.append((name, size)) total_bytes += size repo.ui.debug('%d files, %d bytes to transfer\n' % (len(entries), total_bytes)) svfs = repo.svfs oldaudit = svfs.mustaudit debugflag = repo.ui.debugflag svfs.mustaudit = False def emitrevlogdata(): 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: with svfs(name, 'rb') as fp: yield fp.read(size) else: for chunk in util.filechunkiter(svfs(name), limit=size): yield chunk finally: svfs.mustaudit = oldaudit return len(entries), total_bytes, emitrevlogdata() def generatev1wireproto(repo): """Emit content for version 1 of streaming clone suitable for the wire. This is the data output from ``generatev1()`` with a header line indicating file count and byte size. """ filecount, bytecount, it = generatev1(repo) yield '%d %d\n' % (filecount, bytecount) for chunk in it: yield chunk def generatebundlev1(repo, compression='UN'): """Emit content for version 1 of a stream clone bundle. The first 4 bytes of the output ("HGS1") denote this as stream clone bundle version 1. The next 2 bytes indicate the compression type. Only "UN" is currently supported. The next 16 bytes are two 64-bit big endian unsigned integers indicating file count and byte count, respectively. The next 2 bytes is a 16-bit big endian unsigned short declaring the length of the requirements string, including a trailing \0. The following N bytes are the requirements string, which is ASCII containing a comma-delimited list of repo requirements that are needed to support the data. The remaining content is the output of ``generatev1()`` (which may be compressed in the future). Returns a tuple of (requirements, data generator). """ if compression != 'UN': raise ValueError('we do not support the compression argument yet') requirements = repo.requirements & repo.supportedformats requires = ','.join(sorted(requirements)) def gen(): yield 'HGS1' yield compression filecount, bytecount, it = generatev1(repo) repo.ui.status(_('writing %d bytes for %d files\n') % (bytecount, filecount)) yield struct.pack('>QQ', filecount, bytecount) yield struct.pack('>H', len(requires) + 1) yield requires + '\0' # This is where we'll add compression in the future. assert compression == 'UN' seen = 0 repo.ui.progress(_('bundle'), 0, total=bytecount, unit=_('bytes')) for chunk in it: seen += len(chunk) repo.ui.progress(_('bundle'), seen, total=bytecount, unit=_('bytes')) yield chunk repo.ui.progress(_('bundle'), None) return requirements, gen() def consumev1(repo, fp, filecount, bytecount): """Apply the contents from version 1 of a streaming clone file handle. This takes the output from "streamout" and applies it to the specified repository. Like "streamout," the status line added by the wire protocol is not handled by this function. """ with repo.lock(): repo.ui.status(_('%d files to transfer, %s of data\n') % (filecount, util.bytecount(bytecount))) handled_bytes = 0 repo.ui.progress(_('clone'), 0, total=bytecount, unit=_('bytes')) start = time.time() with repo.transaction('clone'): with repo.svfs.backgroundclosing(repo.ui, expectedcount=filecount): for i in xrange(filecount): # XXX doesn't support '\n' or '\r' in filenames l = fp.readline() try: name, size = l.split('\0', 1) size = int(size) except (ValueError, TypeError): raise error.ResponseError( _('unexpected response from remote server:'), l) if repo.ui.debugflag: repo.ui.debug('adding %s (%s)\n' % (name, util.bytecount(size))) # for backwards compat, name was partially encoded path = store.decodedir(name) with repo.svfs(path, 'w', backgroundclose=True) as ofp: for chunk in util.filechunkiter(fp, limit=size): handled_bytes += len(chunk) repo.ui.progress(_('clone'), handled_bytes, total=bytecount, unit=_('bytes')) ofp.write(chunk) # Writing straight to files circumvented the inmemory caches repo.invalidate() elapsed = time.time() - start if elapsed <= 0: elapsed = 0.001 repo.ui.progress(_('clone'), None) repo.ui.status(_('transferred %s in %.1f seconds (%s/sec)\n') % (util.bytecount(bytecount), elapsed, util.bytecount(bytecount / elapsed))) def readbundle1header(fp): compression = fp.read(2) if compression != 'UN': raise error.Abort(_('only uncompressed stream clone bundles are ' 'supported; got %s') % compression) filecount, bytecount = struct.unpack('>QQ', fp.read(16)) requireslen = struct.unpack('>H', fp.read(2))[0] requires = fp.read(requireslen) if not requires.endswith('\0'): raise error.Abort(_('malformed stream clone bundle: ' 'requirements not properly encoded')) requirements = set(requires.rstrip('\0').split(',')) return filecount, bytecount, requirements def applybundlev1(repo, fp): """Apply the content from a stream clone bundle version 1. We assume the 4 byte header has been read and validated and the file handle is at the 2 byte compression identifier. """ if len(repo): raise error.Abort(_('cannot apply stream clone bundle on non-empty ' 'repo')) filecount, bytecount, requirements = readbundle1header(fp) missingreqs = requirements - repo.supportedformats if missingreqs: raise error.Abort(_('unable to apply stream clone: ' 'unsupported format: %s') % ', '.join(sorted(missingreqs))) consumev1(repo, fp, filecount, bytecount) class streamcloneapplier(object): """Class to manage applying streaming clone bundles. We need to wrap ``applybundlev1()`` in a dedicated type to enable bundle readers to perform bundle type-specific functionality. """ def __init__(self, fh): self._fh = fh def apply(self, repo): return applybundlev1(repo, self._fh)