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view hgext/eol.py @ 40021:c537144fdbef
wireprotov2: support response caching
One of the things I've learned from managing VCS servers over the
years is that they are hard to scale. It is well known that some
companies have very beefy (read: very expensive) servers to power
their VCS needs. It is also known that specialized servers for
various VCS exist in order to facilitate scaling servers. (Mercurial
is in this boat.)
One of the aspects that make a VCS server hard to scale is the
high CPU load incurred by constant client clone/pull operations.
To alleviate the scaling pain associated with data retrieval
operations, I want to integrate caching into the Mercurial wire
protocol server as robustly as possible such that servers can
aggressively cache responses and defer as much server load as
possible.
This commit represents the initial implementation of a general
caching layer in wire protocol version 2.
We define a new interface and behavior for a wire protocol cacher
in repository.py. (This is probably where a reviewer should look
first to understand what is going on.)
The bulk of the added code is in wireprotov2server.py, where we
define how a command can opt in to being cached and integrate
caching into command dispatching.
From a very high-level:
* A command can declare itself as cacheable by providing a callable
that can be used to derive a cache key.
* At dispatch time, if a command is cacheable, we attempt to
construct a cacher and use it for serving the request and/or
caching the request.
* The dispatch layer handles the bulk of the business logic for
caching, making cachers mostly "dumb content stores."
* The mechanism for invalidating cached entries (one of the harder
parts about caching in general) is by varying the cache key when
state changes. As such, cachers don't need to be concerned with
cache invalidation.
Initially, we've hooked up support for caching "manifestdata" and
"filedata" commands. These are the simplest to cache, as they should
be immutable over time. Caching of commands related to changeset
data is a bit harder (because cache validation is impacted by
changes to bookmarks, phases, etc). This will be implemented later.
(Strictly speaking, censoring a file should invalidate caches. I've
added an inline TODO to track this edge case.)
To prove it works, this commit implements a test-only extension
providing in-memory caching backed by an lrucachedict. A new test
showing this extension behaving properly is added. FWIW, the
cacher is ~50 lines of code, demonstrating the relative ease with
which a cache can be added to a server.
While the test cacher is not suitable for production workloads, just
for kicks I performed a clone of just the changeset and manifest data
for the mozilla-unified repository. With a fully warmed cache (of just
the manifest data since changeset data is not cached), server-side
CPU usage dropped from ~73s to ~28s. That's pretty significant and
demonstrates the potential that response caching has on server
scalability!
Differential Revision: https://phab.mercurial-scm.org/D4773
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Wed, 26 Sep 2018 17:16:56 -0700 |
parents | e7aa113b14f7 |
children | d98ec36be808 |
line wrap: on
line source
"""automatically manage newlines in repository files This extension allows you to manage the type of line endings (CRLF or LF) that are used in the repository and in the local working directory. That way you can get CRLF line endings on Windows and LF on Unix/Mac, thereby letting everybody use their OS native line endings. The extension reads its configuration from a versioned ``.hgeol`` configuration file found in the root of the working directory. The ``.hgeol`` file use the same syntax as all other Mercurial configuration files. It uses two sections, ``[patterns]`` and ``[repository]``. The ``[patterns]`` section specifies how line endings should be converted between the working directory and the repository. The format is specified by a file pattern. The first match is used, so put more specific patterns first. The available line endings are ``LF``, ``CRLF``, and ``BIN``. Files with the declared format of ``CRLF`` or ``LF`` are always checked out and stored in the repository in that format and files declared to be binary (``BIN``) are left unchanged. Additionally, ``native`` is an alias for checking out in the platform's default line ending: ``LF`` on Unix (including Mac OS X) and ``CRLF`` on Windows. Note that ``BIN`` (do nothing to line endings) is Mercurial's default behavior; it is only needed if you need to override a later, more general pattern. The optional ``[repository]`` section specifies the line endings to use for files stored in the repository. It has a single setting, ``native``, which determines the storage line endings for files declared as ``native`` in the ``[patterns]`` section. It can be set to ``LF`` or ``CRLF``. The default is ``LF``. For example, this means that on Windows, files configured as ``native`` (``CRLF`` by default) will be converted to ``LF`` when stored in the repository. Files declared as ``LF``, ``CRLF``, or ``BIN`` in the ``[patterns]`` section are always stored as-is in the repository. Example versioned ``.hgeol`` file:: [patterns] **.py = native **.vcproj = CRLF **.txt = native Makefile = LF **.jpg = BIN [repository] native = LF .. note:: The rules will first apply when files are touched in the working directory, e.g. by updating to null and back to tip to touch all files. The extension uses an optional ``[eol]`` section read from both the normal Mercurial configuration files and the ``.hgeol`` file, with the latter overriding the former. You can use that section to control the overall behavior. There are three settings: - ``eol.native`` (default ``os.linesep``) can be set to ``LF`` or ``CRLF`` to override the default interpretation of ``native`` for checkout. This can be used with :hg:`archive` on Unix, say, to generate an archive where files have line endings for Windows. - ``eol.only-consistent`` (default True) can be set to False to make the extension convert files with inconsistent EOLs. Inconsistent means that there is both ``CRLF`` and ``LF`` present in the file. Such files are normally not touched under the assumption that they have mixed EOLs on purpose. - ``eol.fix-trailing-newline`` (default False) can be set to True to ensure that converted files end with a EOL character (either ``\\n`` or ``\\r\\n`` as per the configured patterns). The extension provides ``cleverencode:`` and ``cleverdecode:`` filters like the deprecated win32text extension does. This means that you can disable win32text and enable eol and your filters will still work. You only need to these filters until you have prepared a ``.hgeol`` file. The ``win32text.forbid*`` hooks provided by the win32text extension have been unified into a single hook named ``eol.checkheadshook``. The hook will lookup the expected line endings from the ``.hgeol`` file, which means you must migrate to a ``.hgeol`` file first before using the hook. ``eol.checkheadshook`` only checks heads, intermediate invalid revisions will be pushed. To forbid them completely, use the ``eol.checkallhook`` hook. These hooks are best used as ``pretxnchangegroup`` hooks. See :hg:`help patterns` for more information about the glob patterns used. """ from __future__ import absolute_import import os import re from mercurial.i18n import _ from mercurial import ( config, error as errormod, extensions, match, pycompat, registrar, scmutil, util, ) from mercurial.utils import ( stringutil, ) # Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for # extensions which SHIP WITH MERCURIAL. Non-mainline extensions should # be specifying the version(s) of Mercurial they are tested with, or # leave the attribute unspecified. testedwith = 'ships-with-hg-core' configtable = {} configitem = registrar.configitem(configtable) configitem('eol', 'fix-trailing-newline', default=False, ) configitem('eol', 'native', default=pycompat.oslinesep, ) configitem('eol', 'only-consistent', default=True, ) # Matches a lone LF, i.e., one that is not part of CRLF. singlelf = re.compile('(^|[^\r])\n') def inconsistenteol(data): return '\r\n' in data and singlelf.search(data) def tolf(s, params, ui, **kwargs): """Filter to convert to LF EOLs.""" if stringutil.binary(s): return s if ui.configbool('eol', 'only-consistent') and inconsistenteol(s): return s if (ui.configbool('eol', 'fix-trailing-newline') and s and not s.endswith('\n')): s = s + '\n' return util.tolf(s) def tocrlf(s, params, ui, **kwargs): """Filter to convert to CRLF EOLs.""" if stringutil.binary(s): return s if ui.configbool('eol', 'only-consistent') and inconsistenteol(s): return s if (ui.configbool('eol', 'fix-trailing-newline') and s and not s.endswith('\n')): s = s + '\n' return util.tocrlf(s) def isbinary(s, params): """Filter to do nothing with the file.""" return s filters = { 'to-lf': tolf, 'to-crlf': tocrlf, 'is-binary': isbinary, # The following provide backwards compatibility with win32text 'cleverencode:': tolf, 'cleverdecode:': tocrlf } class eolfile(object): def __init__(self, ui, root, data): self._decode = {'LF': 'to-lf', 'CRLF': 'to-crlf', 'BIN': 'is-binary'} self._encode = {'LF': 'to-lf', 'CRLF': 'to-crlf', 'BIN': 'is-binary'} self.cfg = config.config() # Our files should not be touched. The pattern must be # inserted first override a '** = native' pattern. self.cfg.set('patterns', '.hg*', 'BIN', 'eol') # We can then parse the user's patterns. self.cfg.parse('.hgeol', data) isrepolf = self.cfg.get('repository', 'native') != 'CRLF' self._encode['NATIVE'] = isrepolf and 'to-lf' or 'to-crlf' iswdlf = ui.config('eol', 'native') in ('LF', '\n') self._decode['NATIVE'] = iswdlf and 'to-lf' or 'to-crlf' include = [] exclude = [] self.patterns = [] for pattern, style in self.cfg.items('patterns'): key = style.upper() if key == 'BIN': exclude.append(pattern) else: include.append(pattern) m = match.match(root, '', [pattern]) self.patterns.append((pattern, key, m)) # This will match the files for which we need to care # about inconsistent newlines. self.match = match.match(root, '', [], include, exclude) def copytoui(self, ui): for pattern, key, m in self.patterns: try: ui.setconfig('decode', pattern, self._decode[key], 'eol') ui.setconfig('encode', pattern, self._encode[key], 'eol') except KeyError: ui.warn(_("ignoring unknown EOL style '%s' from %s\n") % (key, self.cfg.source('patterns', pattern))) # eol.only-consistent can be specified in ~/.hgrc or .hgeol for k, v in self.cfg.items('eol'): ui.setconfig('eol', k, v, 'eol') def checkrev(self, repo, ctx, files): failed = [] for f in (files or ctx.files()): if f not in ctx: continue for pattern, key, m in self.patterns: if not m(f): continue target = self._encode[key] data = ctx[f].data() if (target == "to-lf" and "\r\n" in data or target == "to-crlf" and singlelf.search(data)): failed.append((f, target, bytes(ctx))) break return failed def parseeol(ui, repo, nodes): try: for node in nodes: try: if node is None: # Cannot use workingctx.data() since it would load # and cache the filters before we configure them. data = repo.wvfs('.hgeol').read() else: data = repo[node]['.hgeol'].data() return eolfile(ui, repo.root, data) except (IOError, LookupError): pass except errormod.ParseError as inst: ui.warn(_("warning: ignoring .hgeol file due to parse error " "at %s: %s\n") % (inst.args[1], inst.args[0])) return None def ensureenabled(ui): """make sure the extension is enabled when used as hook When eol is used through hooks, the extension is never formally loaded and enabled. This has some side effect, for example the config declaration is never loaded. This function ensure the extension is enabled when running hooks. """ if 'eol' in ui._knownconfig: return ui.setconfig('extensions', 'eol', '', source='internal') extensions.loadall(ui, ['eol']) def _checkhook(ui, repo, node, headsonly): # Get revisions to check and touched files at the same time ensureenabled(ui) files = set() revs = set() for rev in pycompat.xrange(repo[node].rev(), len(repo)): revs.add(rev) if headsonly: ctx = repo[rev] files.update(ctx.files()) for pctx in ctx.parents(): revs.discard(pctx.rev()) failed = [] for rev in revs: ctx = repo[rev] eol = parseeol(ui, repo, [ctx.node()]) if eol: failed.extend(eol.checkrev(repo, ctx, files)) if failed: eols = {'to-lf': 'CRLF', 'to-crlf': 'LF'} msgs = [] for f, target, node in sorted(failed): msgs.append(_(" %s in %s should not have %s line endings") % (f, node, eols[target])) raise errormod.Abort(_("end-of-line check failed:\n") + "\n".join(msgs)) def checkallhook(ui, repo, node, hooktype, **kwargs): """verify that files have expected EOLs""" _checkhook(ui, repo, node, False) def checkheadshook(ui, repo, node, hooktype, **kwargs): """verify that files have expected EOLs""" _checkhook(ui, repo, node, True) # "checkheadshook" used to be called "hook" hook = checkheadshook def preupdate(ui, repo, hooktype, parent1, parent2): p1node = scmutil.resolvehexnodeidprefix(repo, parent1) repo.loadeol([p1node]) return False def uisetup(ui): ui.setconfig('hooks', 'preupdate.eol', preupdate, 'eol') def extsetup(ui): try: extensions.find('win32text') ui.warn(_("the eol extension is incompatible with the " "win32text extension\n")) except KeyError: pass def reposetup(ui, repo): uisetup(repo.ui) if not repo.local(): return for name, fn in filters.iteritems(): repo.adddatafilter(name, fn) ui.setconfig('patch', 'eol', 'auto', 'eol') class eolrepo(repo.__class__): def loadeol(self, nodes): eol = parseeol(self.ui, self, nodes) if eol is None: return None eol.copytoui(self.ui) return eol.match def _hgcleardirstate(self): self._eolmatch = self.loadeol([None, 'tip']) if not self._eolmatch: self._eolmatch = util.never return oldeol = None try: cachemtime = os.path.getmtime(self.vfs.join("eol.cache")) except OSError: cachemtime = 0 else: olddata = self.vfs.read("eol.cache") if olddata: oldeol = eolfile(self.ui, self.root, olddata) try: eolmtime = os.path.getmtime(self.wjoin(".hgeol")) except OSError: eolmtime = 0 if eolmtime > cachemtime: self.ui.debug("eol: detected change in .hgeol\n") hgeoldata = self.wvfs.read('.hgeol') neweol = eolfile(self.ui, self.root, hgeoldata) wlock = None try: wlock = self.wlock() for f in self.dirstate: if self.dirstate[f] != 'n': continue if oldeol is not None: if not oldeol.match(f) and not neweol.match(f): continue oldkey = None for pattern, key, m in oldeol.patterns: if m(f): oldkey = key break newkey = None for pattern, key, m in neweol.patterns: if m(f): newkey = key break if oldkey == newkey: continue # all normal files need to be looked at again since # the new .hgeol file specify a different filter self.dirstate.normallookup(f) # Write the cache to update mtime and cache .hgeol with self.vfs("eol.cache", "w") as f: f.write(hgeoldata) except errormod.LockUnavailable: # If we cannot lock the repository and clear the # dirstate, then a commit might not see all files # as modified. But if we cannot lock the # repository, then we can also not make a commit, # so ignore the error. pass finally: if wlock is not None: wlock.release() def commitctx(self, ctx, error=False): for f in sorted(ctx.added() + ctx.modified()): if not self._eolmatch(f): continue fctx = ctx[f] if fctx is None: continue data = fctx.data() if stringutil.binary(data): # We should not abort here, since the user should # be able to say "** = native" to automatically # have all non-binary files taken care of. continue if inconsistenteol(data): raise errormod.Abort(_("inconsistent newline style " "in %s\n") % f) return super(eolrepo, self).commitctx(ctx, error) repo.__class__ = eolrepo repo._hgcleardirstate()