tests/wireprotosimplecache.py

tests: add test for remotefilelog interactions with hgweb

It's not uncommon for hg users to rely on hgweb as a simple GUI and
history browser (I do this all the time on Mercurial), but we lack any
tests to ensure things keep working.

At present, this merely demonstrates the "view contents of a single
file" endpoint is broken. I'll fix that in a subsequent change.

Differential Revision: https://phab.mercurial-scm.org/D8298

# 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,
    )