view hgext/hgk.py @ 27220:4374d819ccd5

mercurial: implement import hook for handling C/Python modules

There are a handful of modules that have both pure Python and C
extension implementations. Currently, setup.py copies files from
mercurial/pure/*.py to mercurial/ during the install process if C
extensions are not available. This way, "import mercurial.X" will
work whether C extensions are available or not.

This approach has a few drawbacks. First, there aren't run-time checks
verifying the C extensions are loaded when they should be. This could
lead to accidental use of the slower pure Python modules. Second, the
C extensions aren't compatible with PyPy and running Mercurial with
PyPy requires installing Mercurial - you can't run ./hg from a source
checkout. This makes developing while running PyPy somewhat difficult.

This patch implements a PEP-302 import hook for finding and loading the
modules with both C and Python implementations. When a module with dual
implementations is requested for import, its import is handled by our
import hook.

The importer has a mechanism that controls what types of modules we
allow to load. We call this loading behavior the "module load policy."
There are 3 settings:

* Only load C extensions
* Only load pure Python
* Try to load C and fall back to Python

An environment variable allows overriding this policy at run time. This
is mainly useful for developers and for performing actions against the
source checkout (such as installing), which require overriding the
default (strict) policy about requiring C extensions.

The default mode for now is to allow both. This isn't proper and is
technically backwards incompatible. However, it is necessary to
implement a sane patch series that doesn't break the world during
future bisections. The behavior will be corrected in future patch.

We choose the main mercurial/__init__.py module for this code out of
necessity: in a future world, if the custom module importer isn't
registered, we'll fail to find/import certain modules when running
from a pure installation. Without the magical import-time side-effects,
*any* importer of mercurial.* modules would be required to call a
function to register our importer. I'm not a fan of import time side
effects and I initially attempted to do this. However, I was foiled by
our own test harness, which has numerous `python` invoked scripts that
"import mercurial" and fail because the importer isn't registered.
Realizing this problem is probably present in random Python scripts
that have been written over the years, I decided that sacrificing
purity for backwards compatibility is necessary. Plus, if you are
programming Python, "import" should probably "just work."

It's worth noting that now that we have a custom module loader, it
would be possible to hook up demand module proxies at this level
instead of replacing __import__. We leave this work for another time,
if it's even desired.

This patch breaks importing in environments where Mercurial modules
are loaded from a zip file (such as py2exe distributions). This will
be addressed in a subsequent patch.

# Minimal support for git commands on an hg repository
#
# Copyright 2005, 2006 Chris Mason <[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.

'''browse the repository in a graphical way

The hgk extension allows browsing the history of a repository in a
graphical way. It requires Tcl/Tk version 8.4 or later. (Tcl/Tk is not
distributed with Mercurial.)

hgk consists of two parts: a Tcl script that does the displaying and
querying of information, and an extension to Mercurial named hgk.py,
which provides hooks for hgk to get information. hgk can be found in
the contrib directory, and the extension is shipped in the hgext
repository, and needs to be enabled.

The :hg:`view` command will launch the hgk Tcl script. For this command
to work, hgk must be in your search path. Alternately, you can specify
the path to hgk in your configuration file::

  [hgk]
  path = /location/of/hgk

hgk can make use of the extdiff extension to visualize revisions.
Assuming you had already configured extdiff vdiff command, just add::

  [hgk]
  vdiff=vdiff

Revisions context menu will now display additional entries to fire
vdiff on hovered and selected revisions.
'''

import os
from mercurial import cmdutil, commands, patch, scmutil, obsolete
from mercurial.node import nullid, nullrev, short
from mercurial.i18n import _

cmdtable = {}
command = cmdutil.command(cmdtable)
# Note for extension authors: ONLY specify testedwith = 'internal' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'internal'

@command('debug-diff-tree',
    [('p', 'patch', None, _('generate patch')),
    ('r', 'recursive', None, _('recursive')),
    ('P', 'pretty', None, _('pretty')),
    ('s', 'stdin', None, _('stdin')),
    ('C', 'copy', None, _('detect copies')),
    ('S', 'search', "", _('search'))],
    ('[OPTION]... NODE1 NODE2 [FILE]...'),
    inferrepo=True)
def difftree(ui, repo, node1=None, node2=None, *files, **opts):
    """diff trees from two commits"""
    def __difftree(repo, node1, node2, files=[]):
        assert node2 is not None
        mmap = repo[node1].manifest()
        mmap2 = repo[node2].manifest()
        m = scmutil.match(repo[node1], files)
        modified, added, removed  = repo.status(node1, node2, m)[:3]
        empty = short(nullid)

        for f in modified:
            # TODO get file permissions
            ui.write(":100664 100664 %s %s M\t%s\t%s\n" %
                     (short(mmap[f]), short(mmap2[f]), f, f))
        for f in added:
            ui.write(":000000 100664 %s %s N\t%s\t%s\n" %
                     (empty, short(mmap2[f]), f, f))
        for f in removed:
            ui.write(":100664 000000 %s %s D\t%s\t%s\n" %
                     (short(mmap[f]), empty, f, f))
    ##

    while True:
        if opts['stdin']:
            try:
                line = raw_input().split(' ')
                node1 = line[0]
                if len(line) > 1:
                    node2 = line[1]
                else:
                    node2 = None
            except EOFError:
                break
        node1 = repo.lookup(node1)
        if node2:
            node2 = repo.lookup(node2)
        else:
            node2 = node1
            node1 = repo.changelog.parents(node1)[0]
        if opts['patch']:
            if opts['pretty']:
                catcommit(ui, repo, node2, "")
            m = scmutil.match(repo[node1], files)
            diffopts = patch.difffeatureopts(ui)
            diffopts.git = True
            chunks = patch.diff(repo, node1, node2, match=m,
                                opts=diffopts)
            for chunk in chunks:
                ui.write(chunk)
        else:
            __difftree(repo, node1, node2, files=files)
        if not opts['stdin']:
            break

def catcommit(ui, repo, n, prefix, ctx=None):
    nlprefix = '\n' + prefix
    if ctx is None:
        ctx = repo[n]
    # use ctx.node() instead ??
    ui.write(("tree %s\n" % short(ctx.changeset()[0])))
    for p in ctx.parents():
        ui.write(("parent %s\n" % p))

    date = ctx.date()
    description = ctx.description().replace("\0", "")
    ui.write(("author %s %s %s\n" % (ctx.user(), int(date[0]), date[1])))

    if 'committer' in ctx.extra():
        ui.write(("committer %s\n" % ctx.extra()['committer']))

    ui.write(("revision %d\n" % ctx.rev()))
    ui.write(("branch %s\n" % ctx.branch()))
    if obsolete.isenabled(repo, obsolete.createmarkersopt):
        if ctx.obsolete():
            ui.write(("obsolete\n"))
    ui.write(("phase %s\n\n" % ctx.phasestr()))

    if prefix != "":
        ui.write("%s%s\n" % (prefix,
                             description.replace('\n', nlprefix).strip()))
    else:
        ui.write(description + "\n")
    if prefix:
        ui.write('\0')

@command('debug-merge-base', [], _('REV REV'))
def base(ui, repo, node1, node2):
    """output common ancestor information"""
    node1 = repo.lookup(node1)
    node2 = repo.lookup(node2)
    n = repo.changelog.ancestor(node1, node2)
    ui.write(short(n) + "\n")

@command('debug-cat-file',
    [('s', 'stdin', None, _('stdin'))],
    _('[OPTION]... TYPE FILE'),
    inferrepo=True)
def catfile(ui, repo, type=None, r=None, **opts):
    """cat a specific revision"""
    # in stdin mode, every line except the commit is prefixed with two
    # spaces.  This way the our caller can find the commit without magic
    # strings
    #
    prefix = ""
    if opts['stdin']:
        try:
            (type, r) = raw_input().split(' ')
            prefix = "    "
        except EOFError:
            return

    else:
        if not type or not r:
            ui.warn(_("cat-file: type or revision not supplied\n"))
            commands.help_(ui, 'cat-file')

    while r:
        if type != "commit":
            ui.warn(_("aborting hg cat-file only understands commits\n"))
            return 1
        n = repo.lookup(r)
        catcommit(ui, repo, n, prefix)
        if opts['stdin']:
            try:
                (type, r) = raw_input().split(' ')
            except EOFError:
                break
        else:
            break

# git rev-tree is a confusing thing.  You can supply a number of
# commit sha1s on the command line, and it walks the commit history
# telling you which commits are reachable from the supplied ones via
# a bitmask based on arg position.
# you can specify a commit to stop at by starting the sha1 with ^
def revtree(ui, args, repo, full="tree", maxnr=0, parents=False):
    def chlogwalk():
        count = len(repo)
        i = count
        l = [0] * 100
        chunk = 100
        while True:
            if chunk > i:
                chunk = i
                i = 0
            else:
                i -= chunk

            for x in xrange(chunk):
                if i + x >= count:
                    l[chunk - x:] = [0] * (chunk - x)
                    break
                if full is not None:
                    if (i + x) in repo:
                        l[x] = repo[i + x]
                        l[x].changeset() # force reading
                else:
                    if (i + x) in repo:
                        l[x] = 1
            for x in xrange(chunk - 1, -1, -1):
                if l[x] != 0:
                    yield (i + x, full is not None and l[x] or None)
            if i == 0:
                break

    # calculate and return the reachability bitmask for sha
    def is_reachable(ar, reachable, sha):
        if len(ar) == 0:
            return 1
        mask = 0
        for i in xrange(len(ar)):
            if sha in reachable[i]:
                mask |= 1 << i

        return mask

    reachable = []
    stop_sha1 = []
    want_sha1 = []
    count = 0

    # figure out which commits they are asking for and which ones they
    # want us to stop on
    for i, arg in enumerate(args):
        if arg.startswith('^'):
            s = repo.lookup(arg[1:])
            stop_sha1.append(s)
            want_sha1.append(s)
        elif arg != 'HEAD':
            want_sha1.append(repo.lookup(arg))

    # calculate the graph for the supplied commits
    for i, n in enumerate(want_sha1):
        reachable.append(set())
        visit = [n]
        reachable[i].add(n)
        while visit:
            n = visit.pop(0)
            if n in stop_sha1:
                continue
            for p in repo.changelog.parents(n):
                if p not in reachable[i]:
                    reachable[i].add(p)
                    visit.append(p)
                if p in stop_sha1:
                    continue

    # walk the repository looking for commits that are in our
    # reachability graph
    for i, ctx in chlogwalk():
        if i not in repo:
            continue
        n = repo.changelog.node(i)
        mask = is_reachable(want_sha1, reachable, n)
        if mask:
            parentstr = ""
            if parents:
                pp = repo.changelog.parents(n)
                if pp[0] != nullid:
                    parentstr += " " + short(pp[0])
                if pp[1] != nullid:
                    parentstr += " " + short(pp[1])
            if not full:
                ui.write("%s%s\n" % (short(n), parentstr))
            elif full == "commit":
                ui.write("%s%s\n" % (short(n), parentstr))
                catcommit(ui, repo, n, '    ', ctx)
            else:
                (p1, p2) = repo.changelog.parents(n)
                (h, h1, h2) = map(short, (n, p1, p2))
                (i1, i2) = map(repo.changelog.rev, (p1, p2))

                date = ctx.date()[0]
                ui.write("%s %s:%s" % (date, h, mask))
                mask = is_reachable(want_sha1, reachable, p1)
                if i1 != nullrev and mask > 0:
                    ui.write("%s:%s " % (h1, mask)),
                mask = is_reachable(want_sha1, reachable, p2)
                if i2 != nullrev and mask > 0:
                    ui.write("%s:%s " % (h2, mask))
                ui.write("\n")
            if maxnr and count >= maxnr:
                break
            count += 1

# git rev-list tries to order things by date, and has the ability to stop
# at a given commit without walking the whole repo.  TODO add the stop
# parameter
@command('debug-rev-list',
    [('H', 'header', None, _('header')),
    ('t', 'topo-order', None, _('topo-order')),
    ('p', 'parents', None, _('parents')),
    ('n', 'max-count', 0, _('max-count'))],
    ('[OPTION]... REV...'))
def revlist(ui, repo, *revs, **opts):
    """print revisions"""
    if opts['header']:
        full = "commit"
    else:
        full = None
    copy = [x for x in revs]
    revtree(ui, copy, repo, full, opts['max_count'], opts['parents'])

@command('view',
    [('l', 'limit', '',
     _('limit number of changes displayed'), _('NUM'))],
    _('[-l LIMIT] [REVRANGE]'))
def view(ui, repo, *etc, **opts):
    "start interactive history viewer"
    os.chdir(repo.root)
    optstr = ' '.join(['--%s %s' % (k, v) for k, v in opts.iteritems() if v])
    if repo.filtername is None:
        optstr += '--hidden'

    cmd = ui.config("hgk", "path", "hgk") + " %s %s" % (optstr, " ".join(etc))
    ui.debug("running %s\n" % cmd)
    ui.system(cmd)