view tests/wireprotosimplecache.py @ 40417:49c7b701fdc2 stable

phase: add an archived phase

This phase allows for hidden changesets in the "user space". It differs from
the "internal" phase which is intended for internal by-product only. There
have been discussions at the 4.8 sprint to use such phase to speedup cleanup
after history rewriting operation.

Shipping it in the same release as the 'internal-phase' groups the associated
`requires` entry. The important bit is to have support for this phase in the
earliest version of mercurial possible. Adding the UI to manipulate this new
phase later seems fine.

The current plan for archived usage and user interface are as follow. On a
repository with internal-phase on and evolution off:

* history rewriting command set rewritten changeset in the archived phase.
  (This mean updating the cleanupnodes method).
* keep `hg unbundle .hg/strip-backup/X.hg` as a way to restore changeset for
  now
  (backup bundle need to contains phase data)
* [maybe] add a `hg strip --soft` advance flag
  (a light way to expose the feature without getting in the way of a better
  UI)

Mercurial 4.8 freeze is too close to get the above in by then.

We don't introduce a new repository `requirement` as we reuse the one
introduced with the 'archived' phase during the 4.8 cycle.

# wireprotosimplecache.py - Extension providing in-memory wire protocol cache
#
# Copyright 2018 Gregory Szorc <[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.

from __future__ import absolute_import

from mercurial import (
    extensions,
    registrar,
    repository,
    util,
    wireprotoserver,
    wireprototypes,
    wireprotov2server,
)
from mercurial.utils import (
    interfaceutil,
    stringutil,
)

CACHE = None

configtable = {}
configitem = registrar.configitem(configtable)

configitem(b'simplecache', b'cacheapi',
           default=False)
configitem(b'simplecache', b'cacheobjects',
           default=False)
configitem(b'simplecache', b'redirectsfile',
           default=None)

# API handler that makes cached keys available.
def handlecacherequest(rctx, req, res, checkperm, urlparts):
    if rctx.repo.ui.configbool(b'simplecache', b'cacheobjects'):
        res.status = b'500 Internal Server Error'
        res.setbodybytes(b'cacheobjects not supported for api server')
        return

    if not urlparts:
        res.status = b'200 OK'
        res.headers[b'Content-Type'] = b'text/plain'
        res.setbodybytes(b'simple cache server')
        return

    key = b'/'.join(urlparts)

    if key not in CACHE:
        res.status = b'404 Not Found'
        res.headers[b'Content-Type'] = b'text/plain'
        res.setbodybytes(b'key not found in cache')
        return

    res.status = b'200 OK'
    res.headers[b'Content-Type'] = b'application/mercurial-cbor'
    res.setbodybytes(CACHE[key])

def cachedescriptor(req, repo):
    return {}

wireprotoserver.API_HANDLERS[b'simplecache'] = {
    b'config': (b'simplecache', b'cacheapi'),
    b'handler': handlecacherequest,
    b'apidescriptor': cachedescriptor,
}

@interfaceutil.implementer(repository.iwireprotocolcommandcacher)
class memorycacher(object):
    def __init__(self, ui, command, encodefn, redirecttargets, redirecthashes,
                 req):
        self.ui = ui
        self.encodefn = encodefn
        self.redirecttargets = redirecttargets
        self.redirecthashes = redirecthashes
        self.req = req
        self.key = None
        self.cacheobjects = ui.configbool(b'simplecache', b'cacheobjects')
        self.cacheapi = ui.configbool(b'simplecache', b'cacheapi')
        self.buffered = []

        ui.log(b'simplecache', b'cacher constructed for %s\n', command)

    def __enter__(self):
        return self

    def __exit__(self, exctype, excvalue, exctb):
        if exctype:
            self.ui.log(b'simplecache', b'cacher exiting due to error\n')

    def adjustcachekeystate(self, state):
        # Needed in order to make tests deterministic. Don't copy this
        # pattern for production caches!
        del state[b'repo']

    def setcachekey(self, key):
        self.key = key
        return True

    def lookup(self):
        if self.key not in CACHE:
            self.ui.log(b'simplecache', b'cache miss for %s\n', self.key)
            return None

        entry = CACHE[self.key]
        self.ui.log(b'simplecache', b'cache hit for %s\n', self.key)

        redirectable = True

        if not self.cacheapi:
            redirectable = False
        elif not self.redirecttargets:
            redirectable = False
        else:
            clienttargets = set(self.redirecttargets)
            ourtargets = set(t[b'name'] for t in loadredirecttargets(self.ui))

            # We only ever redirect to a single target (for now). So we don't
            # need to store which target matched.
            if not clienttargets & ourtargets:
                redirectable = False

        if redirectable:
            paths = self.req.dispatchparts[:-3]
            paths.append(b'simplecache')
            paths.append(self.key)

            url = b'%s/%s' % (self.req.baseurl, b'/'.join(paths))

            #url = b'http://example.com/%s' % self.key
            self.ui.log(b'simplecache', b'sending content redirect for %s to '
                                        b'%s\n', self.key, url)
            response = wireprototypes.alternatelocationresponse(
                url=url,
                mediatype=b'application/mercurial-cbor')

            return {b'objs': [response]}

        if self.cacheobjects:
            return {
                b'objs': entry,
            }
        else:
            return {
                b'objs': [wireprototypes.encodedresponse(entry)],
            }

    def onobject(self, obj):
        if self.cacheobjects:
            self.buffered.append(obj)
        else:
            self.buffered.extend(self.encodefn(obj))

        yield obj

    def onfinished(self):
        self.ui.log(b'simplecache', b'storing cache entry for %s\n', self.key)
        if self.cacheobjects:
            CACHE[self.key] = self.buffered
        else:
            CACHE[self.key] = b''.join(self.buffered)

        return []

def makeresponsecacher(orig, repo, proto, command, args, objencoderfn,
                       redirecttargets, redirecthashes):
    return memorycacher(repo.ui, command, objencoderfn, redirecttargets,
                        redirecthashes, proto._req)

def loadredirecttargets(ui):
    path = ui.config(b'simplecache', b'redirectsfile')
    if not path:
        return []

    with open(path, 'rb') as fh:
        s = fh.read()

    return stringutil.evalpythonliteral(s)

def getadvertisedredirecttargets(orig, repo, proto):
    return loadredirecttargets(repo.ui)

def extsetup(ui):
    global CACHE

    CACHE = util.lrucachedict(10000)

    extensions.wrapfunction(wireprotov2server, b'makeresponsecacher',
                            makeresponsecacher)
    extensions.wrapfunction(wireprotov2server, b'getadvertisedredirecttargets',
                            getadvertisedredirecttargets)