tests/wireprotosimplecache.py

clone: make sure we warm the cache after a clone

This work around any deviciency/limitation of the clone process. In our case
this ensure the persistent nodemap exist with valid content.

Ideally, the cloning process would also do "the right thing". However since
older server will never be able to do "the right thing". The local workaround
will be necessary anyway.

I am not worried by the performance impact of this as `hg clone` is non-instant
on large repositories where is could matters. Warming the cache if they are
already correct is very fast. And if they are not already warm, this seems like
a good time to do so.

This impact various test as more cache are now warmed sooner, all the change
should be harmless.

Differential Revision: https://phab.mercurial-scm.org/D9789

# 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,
    util,
    wireprotoserver,
    wireprototypes,
    wireprotov2server,
)
from mercurial.interfaces import (
    repository,
    util as interfaceutil,
)
from mercurial.utils import 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 = {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,
    )