view tests/wireprotosimplecache.py @ 41051:bad05a6afdc8

pull: fix inconsistent view of bookmarks during pull (issue4700)

I had a share where a pull apparently pulled a bookmark but not the
revision pointed to by the bookmark, which I suspect is due to this
(and if not, we might as well remove known issues in this area).

I do this by combining doing all the queries that could read the
bookmarks in one round trip.

I had to change the handling of the case where the server doesn't
support the lookup query, because if it fails, it would otherwise make
fremotebookmark.result() block forever. This is due to
wireprotov1peer.peerexecutor.sendcommands's behavior (it fills a
single future if any query fails synchronously and leaves all other
futures unchanged), but I don't know if the fix is to cancel all other
futures, or to keep going with the other queries.

Differential Revision: https://phab.mercurial-scm.org/D5449

# 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)