view mercurial/unionrepo.py @ 29847:9a9629b9416c stable

bundle2: fail faster when interrupted

Before this patch, bundle2 application attempted to consume remaining
bundle2 part data when the process is interrupted (SIGINT) or when
sys.exit is called (translated into a SystemExit exception). This
meant that if one of these occurred when applying a say 1 GB
changegroup bundle2 part being downloaded over a network, it may take
Mercurial *several minutes* to terminate after a SIGINT because the
process is waiting on the network to stream megabytes of data. This is
not a great user experience and a regression from bundle1. Furthermore,
many process supervisors tend to only give processes a finite amount of
time to exit after delivering SIGINT: if processes take too long to
self-terminate, a SIGKILL is issued and Mercurial has no opportunity to
clean up. This would mean orphaned locks and transactions. Not good.

This patch changes the bundle2 application behavior to fail faster
when an interrupt or system exit is requested. It does so by not
catching BaseException (which includes KeyboardInterrupt and
SystemExit) and by explicitly checking for these conditions in
yet another handler which would also seek to the end of the current
bundle2 part on failure.

The end result of this patch is that SIGINT is now reacted to
significantly faster: the active transaction is rolled back
immediately without waiting for incoming bundle2 data to be consumed.
This restores the pre-bundle2 behavior and makes Mercurial treat
signals with the urgency they deserve.

# unionrepo.py - repository class for viewing union of repository changesets
#
# Derived from bundlerepo.py
# Copyright 2006, 2007 Benoit Boissinot <[e-mail]>
# Copyright 2013 Unity Technologies, Mads Kiilerich <[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.

"""Repository class for "in-memory pull" of one local repository to another,
allowing operations like diff and log with revsets.
"""

from __future__ import absolute_import

import os

from .i18n import _
from .node import nullid

from . import (
    changelog,
    cmdutil,
    error,
    filelog,
    localrepo,
    manifest,
    mdiff,
    pathutil,
    revlog,
    scmutil,
    util,
)

class unionrevlog(revlog.revlog):
    def __init__(self, opener, indexfile, revlog2, linkmapper):
        # How it works:
        # To retrieve a revision, we just need to know the node id so we can
        # look it up in revlog2.
        #
        # To differentiate a rev in the second revlog from a rev in the revlog,
        # we check revision against repotiprev.
        opener = scmutil.readonlyvfs(opener)
        revlog.revlog.__init__(self, opener, indexfile)
        self.revlog2 = revlog2

        n = len(self)
        self.repotiprev = n - 1
        self.bundlerevs = set() # used by 'bundle()' revset expression
        for rev2 in self.revlog2:
            rev = self.revlog2.index[rev2]
            # rev numbers - in revlog2, very different from self.rev
            _start, _csize, _rsize, base, linkrev, p1rev, p2rev, node = rev
            flags = _start & 0xFFFF

            if linkmapper is None: # link is to same revlog
                assert linkrev == rev2 # we never link back
                link = n
            else: # rev must be mapped from repo2 cl to unified cl by linkmapper
                link = linkmapper(linkrev)

            if linkmapper is not None: # link is to same revlog
                base = linkmapper(base)

            if node in self.nodemap:
                # this happens for the common revlog revisions
                self.bundlerevs.add(self.nodemap[node])
                continue

            p1node = self.revlog2.node(p1rev)
            p2node = self.revlog2.node(p2rev)

            e = (flags, None, None, base,
                 link, self.rev(p1node), self.rev(p2node), node)
            self.index.insert(-1, e)
            self.nodemap[node] = n
            self.bundlerevs.add(n)
            n += 1

    def _chunk(self, rev):
        if rev <= self.repotiprev:
            return revlog.revlog._chunk(self, rev)
        return self.revlog2._chunk(self.node(rev))

    def revdiff(self, rev1, rev2):
        """return or calculate a delta between two revisions"""
        if rev1 > self.repotiprev and rev2 > self.repotiprev:
            return self.revlog2.revdiff(
                self.revlog2.rev(self.node(rev1)),
                self.revlog2.rev(self.node(rev2)))
        elif rev1 <= self.repotiprev and rev2 <= self.repotiprev:
            return self.baserevdiff(rev1, rev2)

        return mdiff.textdiff(self.revision(self.node(rev1)),
                              self.revision(self.node(rev2)))

    def revision(self, nodeorrev):
        """return an uncompressed revision of a given node or revision
        number.
        """
        if isinstance(nodeorrev, int):
            rev = nodeorrev
            node = self.node(rev)
        else:
            node = nodeorrev
            rev = self.rev(node)

        if node == nullid:
            return ""

        if rev > self.repotiprev:
            text = self.revlog2.revision(node)
            self._cache = (node, rev, text)
        else:
            text = self.baserevision(rev)
            # already cached
        return text

    def baserevision(self, nodeorrev):
        # Revlog subclasses may override 'revision' method to modify format of
        # content retrieved from revlog. To use unionrevlog with such class one
        # needs to override 'baserevision' and make more specific call here.
        return revlog.revlog.revision(self, nodeorrev)

    def baserevdiff(self, rev1, rev2):
        # Exists for the same purpose as baserevision.
        return revlog.revlog.revdiff(self, rev1, rev2)

    def addrevision(self, text, transaction, link, p1=None, p2=None, d=None):
        raise NotImplementedError
    def addgroup(self, revs, linkmapper, transaction):
        raise NotImplementedError
    def strip(self, rev, minlink):
        raise NotImplementedError
    def checksize(self):
        raise NotImplementedError

class unionchangelog(unionrevlog, changelog.changelog):
    def __init__(self, opener, opener2):
        changelog.changelog.__init__(self, opener)
        linkmapper = None
        changelog2 = changelog.changelog(opener2)
        unionrevlog.__init__(self, opener, self.indexfile, changelog2,
                             linkmapper)

    def baserevision(self, nodeorrev):
        # Although changelog doesn't override 'revision' method, some extensions
        # may replace this class with another that does. Same story with
        # manifest and filelog classes.
        return changelog.changelog.revision(self, nodeorrev)

    def baserevdiff(self, rev1, rev2):
        return changelog.changelog.revdiff(self, rev1, rev2)

class unionmanifest(unionrevlog, manifest.manifest):
    def __init__(self, opener, opener2, linkmapper):
        manifest.manifest.__init__(self, opener)
        manifest2 = manifest.manifest(opener2)
        unionrevlog.__init__(self, opener, self.indexfile, manifest2,
                             linkmapper)

    def baserevision(self, nodeorrev):
        return manifest.manifest.revision(self, nodeorrev)

    def baserevdiff(self, rev1, rev2):
        return manifest.manifest.revdiff(self, rev1, rev2)

class unionfilelog(unionrevlog, filelog.filelog):
    def __init__(self, opener, path, opener2, linkmapper, repo):
        filelog.filelog.__init__(self, opener, path)
        filelog2 = filelog.filelog(opener2, path)
        unionrevlog.__init__(self, opener, self.indexfile, filelog2,
                             linkmapper)
        self._repo = repo

    def baserevision(self, nodeorrev):
        return filelog.filelog.revision(self, nodeorrev)

    def baserevdiff(self, rev1, rev2):
        return filelog.filelog.revdiff(self, rev1, rev2)

    def iscensored(self, rev):
        """Check if a revision is censored."""
        if rev <= self.repotiprev:
            return filelog.filelog.iscensored(self, rev)
        node = self.node(rev)
        return self.revlog2.iscensored(self.revlog2.rev(node))

class unionpeer(localrepo.localpeer):
    def canpush(self):
        return False

class unionrepository(localrepo.localrepository):
    def __init__(self, ui, path, path2):
        localrepo.localrepository.__init__(self, ui, path)
        self.ui.setconfig('phases', 'publish', False, 'unionrepo')

        self._url = 'union:%s+%s' % (util.expandpath(path),
                                     util.expandpath(path2))
        self.repo2 = localrepo.localrepository(ui, path2)

    @localrepo.unfilteredpropertycache
    def changelog(self):
        return unionchangelog(self.svfs, self.repo2.svfs)

    def _clrev(self, rev2):
        """map from repo2 changelog rev to temporary rev in self.changelog"""
        node = self.repo2.changelog.node(rev2)
        return self.changelog.rev(node)

    @localrepo.unfilteredpropertycache
    def manifest(self):
        return unionmanifest(self.svfs, self.repo2.svfs,
                             self.unfiltered()._clrev)

    def url(self):
        return self._url

    def file(self, f):
        return unionfilelog(self.svfs, f, self.repo2.svfs,
                            self.unfiltered()._clrev, self)

    def close(self):
        self.repo2.close()

    def cancopy(self):
        return False

    def peer(self):
        return unionpeer(self)

    def getcwd(self):
        return os.getcwd() # always outside the repo

def instance(ui, path, create):
    if create:
        raise error.Abort(_('cannot create new union repository'))
    parentpath = ui.config("bundle", "mainreporoot", "")
    if not parentpath:
        # try to find the correct path to the working directory repo
        parentpath = cmdutil.findrepo(os.getcwd())
        if parentpath is None:
            parentpath = ''
    if parentpath:
        # Try to make the full path relative so we get a nice, short URL.
        # In particular, we don't want temp dir names in test outputs.
        cwd = os.getcwd()
        if parentpath == cwd:
            parentpath = ''
        else:
            cwd = pathutil.normasprefix(cwd)
            if parentpath.startswith(cwd):
                parentpath = parentpath[len(cwd):]
    if path.startswith('union:'):
        s = path.split(":", 1)[1].split("+", 1)
        if len(s) == 1:
            repopath, repopath2 = parentpath, s[0]
        else:
            repopath, repopath2 = s
    else:
        repopath, repopath2 = parentpath, path
    return unionrepository(ui, repopath, repopath2)