annotate mercurial/graphmod.py @ 37716:dfc51a482031

registrar: replace "cmdtype" with an intent-based mechanism (API)

Commands perform varied actions and repositories vary in their
capabilities.

Historically, the .hg/requires file has been used to lock out clients
lacking a requirement. But this is a very heavy-handed approach and
is typically reserved for cases where the on-disk storage format
changes and we want to prevent incompatible clients from operating on
a repo.

Outside of the .hg/requires file, we tend to deal with things like
optional, extension-provided features via checking at call sites.
We'll either have checks in core or extensions will monkeypatch
functions in core disabling incompatible features, enabling new
features, etc.

Things are somewhat tolerable today. But once we introduce alternate
storage backends with varying support for repository features and
vastly different modes of behavior, the current model will quickly
grow unwieldy. For example, the implementation of the "simple store"
required a lot of hacks to deal with stripping and verify because
various parts of core assume things are implemented a certain way.
Partial clone will require new ways of modeling file data retrieval,
because we can no longer assume that all file data is already local.
In this new world, some commands might not make any sense for certain
types of repositories.

What we need is a mechanism to affect the construction of repository
(and eventually peer) instances so the requirements/capabilities
needed for the current operation can be taken into account. "Current
operation" can almost certainly be defined by a command. So it makes
sense for commands to declare their intended actions.

This commit introduces the "intents" concept on the command registrar.
"intents" captures a set of strings that declare actions that are
anticipated to be taken, requirements the repository must possess, etc.
These intents will be passed into hg.repo(), which will pass them into
localrepository, where they can be used to influence the object being
created. Some use cases for this include:

* For read-only intents, constructing a repository object that doesn't
  expose methods that can mutate the repository. Its VFS instances
  don't even allow opening a file with write access.
* For read-only intents, constructing a repository object without
  cache invalidation logic. If the repo never changes during its lifetime,
  nothing ever needs to be invalidated and we don't need to do expensive
  things like verify the changelog's hidden revisions state is accurate
  every time we access repo.changelog.
* We can automatically hide commands from `hg help` when the current
  repository doesn't provide that command. For example, an alternate
  storage backend may not support `hg commit`, so we can hide that
  command or anything else that would perform local commits.

We already kind of had an "intents" mechanism on the registrar in the
form of "cmdtype." However, it was never used. And it was limited to
a single value. We really need something that supports multiple
intents. And because intents may be defined by extensions and at this
point are advisory, I think it is best to define them in a set rather
than as separate arguments/attributes on the command.

Differential Revision: https://phab.mercurial-scm.org/D3376

# Revision graph generator for Mercurial
#
# Copyright 2008 Dirkjan Ochtman <[e-mail]>
# Copyright 2007 Joel Rosdahl <[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.

"""supports walking the history as DAGs suitable for graphical output

The most basic format we use is that of::

  (id, type, data, [parentids])

The node and parent ids are arbitrary integers which identify a node in the
context of the graph returned. Type is a constant specifying the node type.
Data depends on type.
"""

from __future__ import absolute_import

from .node import nullrev
from . import (
    dagop,
    smartset,
    util,
)

CHANGESET = 'C'
PARENT = 'P'
GRANDPARENT = 'G'
MISSINGPARENT = 'M'
# Style of line to draw. None signals a line that ends and is removed at this
# point. A number prefix means only the last N characters of the current block
# will use that style, the rest will use the PARENT style. Add a - sign
# (so making N negative) and all but the first N characters use that style.
EDGES = {PARENT: '|', GRANDPARENT: ':', MISSINGPARENT: None}

def dagwalker(repo, revs):
    """cset DAG generator yielding (id, CHANGESET, ctx, [parentinfo]) tuples

    This generator function walks through revisions (which should be ordered
    from bigger to lower). It returns a tuple for each node.

    Each parentinfo entry is a tuple with (edgetype, parentid), where edgetype
    is one of PARENT, GRANDPARENT or MISSINGPARENT. The node and parent ids
    are arbitrary integers which identify a node in the context of the graph
    returned.

    """
    gpcache = {}

    for rev in revs:
        ctx = repo[rev]
        # partition into parents in the rev set and missing parents, then
        # augment the lists with markers, to inform graph drawing code about
        # what kind of edge to draw between nodes.
        pset = set(p.rev() for p in ctx.parents() if p.rev() in revs)
        mpars = [p.rev() for p in ctx.parents()
                 if p.rev() != nullrev and p.rev() not in pset]
        parents = [(PARENT, p) for p in sorted(pset)]

        for mpar in mpars:
            gp = gpcache.get(mpar)
            if gp is None:
                # precompute slow query as we know reachableroots() goes
                # through all revs (issue4782)
                if not isinstance(revs, smartset.baseset):
                    revs = smartset.baseset(revs)
                gp = gpcache[mpar] = sorted(set(dagop.reachableroots(
                    repo, revs, [mpar])))
            if not gp:
                parents.append((MISSINGPARENT, mpar))
                pset.add(mpar)
            else:
                parents.extend((GRANDPARENT, g) for g in gp if g not in pset)
                pset.update(gp)

        yield (ctx.rev(), CHANGESET, ctx, parents)

def nodes(repo, nodes):
    """cset DAG generator yielding (id, CHANGESET, ctx, [parentids]) tuples

    This generator function walks the given nodes. It only returns parents
    that are in nodes, too.
    """
    include = set(nodes)
    for node in nodes:
        ctx = repo[node]
        parents = set((PARENT, p.rev()) for p in ctx.parents()
                      if p.node() in include)
        yield (ctx.rev(), CHANGESET, ctx, sorted(parents))

def colored(dag, repo):
    """annotates a DAG with colored edge information

    For each DAG node this function emits tuples::

      (id, type, data, (col, color), [(col, nextcol, color)])

    with the following new elements:

      - Tuple (col, color) with column and color index for the current node
      - A list of tuples indicating the edges between the current node and its
        parents.
    """
    seen = []
    colors = {}
    newcolor = 1
    config = {}

    for key, val in repo.ui.configitems('graph'):
        if '.' in key:
            branch, setting = key.rsplit('.', 1)
            # Validation
            if setting == "width" and val.isdigit():
                config.setdefault(branch, {})[setting] = int(val)
            elif setting == "color" and val.isalnum():
                config.setdefault(branch, {})[setting] = val

    if config:
        getconf = util.lrucachefunc(
            lambda rev: config.get(repo[rev].branch(), {}))
    else:
        getconf = lambda rev: {}

    for (cur, type, data, parents) in dag:

        # Compute seen and next
        if cur not in seen:
            seen.append(cur) # new head
            colors[cur] = newcolor
            newcolor += 1

        col = seen.index(cur)
        color = colors.pop(cur)
        next = seen[:]

        # Add parents to next
        addparents = [p for pt, p in parents if p not in next]
        next[col:col + 1] = addparents

        # Set colors for the parents
        for i, p in enumerate(addparents):
            if not i:
                colors[p] = color
            else:
                colors[p] = newcolor
                newcolor += 1

        # Add edges to the graph
        edges = []
        for ecol, eid in enumerate(seen):
            if eid in next:
                bconf = getconf(eid)
                edges.append((
                    ecol, next.index(eid), colors[eid],
                    bconf.get('width', -1),
                    bconf.get('color', '')))
            elif eid == cur:
                for ptype, p in parents:
                    bconf = getconf(p)
                    edges.append((
                        ecol, next.index(p), color,
                        bconf.get('width', -1),
                        bconf.get('color', '')))

        # Yield and move on
        yield (cur, type, data, (col, color), edges)
        seen = next

def asciiedges(type, char, state, rev, parents):
    """adds edge info to changelog DAG walk suitable for ascii()"""
    seen = state['seen']
    if rev not in seen:
        seen.append(rev)
    nodeidx = seen.index(rev)

    knownparents = []
    newparents = []
    for ptype, parent in parents:
        if parent == rev:
            # self reference (should only be seen in null rev)
            continue
        if parent in seen:
            knownparents.append(parent)
        else:
            newparents.append(parent)
            state['edges'][parent] = state['styles'].get(ptype, '|')

    ncols = len(seen)
    width = 1 + ncols * 2
    nextseen = seen[:]
    nextseen[nodeidx:nodeidx + 1] = newparents
    edges = [(nodeidx, nextseen.index(p)) for p in knownparents]

    seen[:] = nextseen
    while len(newparents) > 2:
        # ascii() only knows how to add or remove a single column between two
        # calls. Nodes with more than two parents break this constraint so we
        # introduce intermediate expansion lines to grow the active node list
        # slowly.
        edges.append((nodeidx, nodeidx))
        edges.append((nodeidx, nodeidx + 1))
        nmorecols = 1
        width += 2
        yield (type, char, width, (nodeidx, edges, ncols, nmorecols))
        char = '\\'
        nodeidx += 1
        ncols += 1
        edges = []
        del newparents[0]

    if len(newparents) > 0:
        edges.append((nodeidx, nodeidx))
    if len(newparents) > 1:
        edges.append((nodeidx, nodeidx + 1))
    nmorecols = len(nextseen) - ncols
    if nmorecols > 0:
        width += 2
    # remove current node from edge characters, no longer needed
    state['edges'].pop(rev, None)
    yield (type, char, width, (nodeidx, edges, ncols, nmorecols))

def _fixlongrightedges(edges):
    for (i, (start, end)) in enumerate(edges):
        if end > start:
            edges[i] = (start, end + 1)

def _getnodelineedgestail(
        echars, idx, pidx, ncols, coldiff, pdiff, fix_tail):
    if fix_tail and coldiff == pdiff and coldiff != 0:
        # Still going in the same non-vertical direction.
        if coldiff == -1:
            start = max(idx + 1, pidx)
            tail = echars[idx * 2:(start - 1) * 2]
            tail.extend(["/", " "] * (ncols - start))
            return tail
        else:
            return ["\\", " "] * (ncols - idx - 1)
    else:
        remainder = (ncols - idx - 1)
        return echars[-(remainder * 2):] if remainder > 0 else []

def _drawedges(echars, edges, nodeline, interline):
    for (start, end) in edges:
        if start == end + 1:
            interline[2 * end + 1] = "/"
        elif start == end - 1:
            interline[2 * start + 1] = "\\"
        elif start == end:
            interline[2 * start] = echars[2 * start]
        else:
            if 2 * end >= len(nodeline):
                continue
            nodeline[2 * end] = "+"
            if start > end:
                (start, end) = (end, start)
            for i in range(2 * start + 1, 2 * end):
                if nodeline[i] != "+":
                    nodeline[i] = "-"

def _getpaddingline(echars, idx, ncols, edges):
    # all edges up to the current node
    line = echars[:idx * 2]
    # an edge for the current node, if there is one
    if (idx, idx - 1) in edges or (idx, idx) in edges:
        # (idx, idx - 1)      (idx, idx)
        # | | | |           | | | |
        # +---o |           | o---+
        # | | X |           | X | |
        # | |/ /            | |/ /
        # | | |             | | |
        line.extend(echars[idx * 2:(idx + 1) * 2])
    else:
        line.extend([' ', ' '])
    # all edges to the right of the current node
    remainder = ncols - idx - 1
    if remainder > 0:
        line.extend(echars[-(remainder * 2):])
    return line

def _drawendinglines(lines, extra, edgemap, seen):
    """Draw ending lines for missing parent edges

    None indicates an edge that ends at between this node and the next
    Replace with a short line ending in ~ and add / lines to any edges to
    the right.

    """
    if None not in edgemap.values():
        return

    # Check for more edges to the right of our ending edges.
    # We need enough space to draw adjustment lines for these.
    edgechars = extra[::2]
    while edgechars and edgechars[-1] is None:
        edgechars.pop()
    shift_size = max((edgechars.count(None) * 2) - 1, 0)
    while len(lines) < 3 + shift_size:
        lines.append(extra[:])

    if shift_size:
        empties = []
        toshift = []
        first_empty = extra.index(None)
        for i, c in enumerate(extra[first_empty::2], first_empty // 2):
            if c is None:
                empties.append(i * 2)
            else:
                toshift.append(i * 2)
        targets = list(range(first_empty, first_empty + len(toshift) * 2, 2))
        positions = toshift[:]
        for line in lines[-shift_size:]:
            line[first_empty:] = [' '] * (len(line) - first_empty)
            for i in range(len(positions)):
                pos = positions[i] - 1
                positions[i] = max(pos, targets[i])
                line[pos] = '/' if pos > targets[i] else extra[toshift[i]]

    map = {1: '|', 2: '~'}
    for i, line in enumerate(lines):
        if None not in line:
            continue
        line[:] = [c or map.get(i, ' ') for c in line]

    # remove edges that ended
    remove = [p for p, c in edgemap.items() if c is None]
    for parent in remove:
        del edgemap[parent]
        seen.remove(parent)

def asciistate():
    """returns the initial value for the "state" argument to ascii()"""
    return {
        'seen': [],
        'edges': {},
        'lastcoldiff': 0,
        'lastindex': 0,
        'styles': EDGES.copy(),
        'graphshorten': False,
    }

def ascii(ui, state, type, char, text, coldata):
    """prints an ASCII graph of the DAG

    takes the following arguments (one call per node in the graph):

      - ui to write to
      - Somewhere to keep the needed state in (init to asciistate())
      - Column of the current node in the set of ongoing edges.
      - Type indicator of node data, usually 'C' for changesets.
      - Payload: (char, lines):
        - Character to use as node's symbol.
        - List of lines to display as the node's text.
      - Edges; a list of (col, next_col) indicating the edges between
        the current node and its parents.
      - Number of columns (ongoing edges) in the current revision.
      - The difference between the number of columns (ongoing edges)
        in the next revision and the number of columns (ongoing edges)
        in the current revision. That is: -1 means one column removed;
        0 means no columns added or removed; 1 means one column added.
    """
    idx, edges, ncols, coldiff = coldata
    assert -2 < coldiff < 2

    edgemap, seen = state['edges'], state['seen']
    # Be tolerant of history issues; make sure we have at least ncols + coldiff
    # elements to work with. See test-glog.t for broken history test cases.
    echars = [c for p in seen for c in (edgemap.get(p, '|'), ' ')]
    echars.extend(('|', ' ') * max(ncols + coldiff - len(seen), 0))

    if coldiff == -1:
        # Transform
        #
        #     | | |        | | |
        #     o | |  into  o---+
        #     |X /         |/ /
        #     | |          | |
        _fixlongrightedges(edges)

    # add_padding_line says whether to rewrite
    #
    #     | | | |        | | | |
    #     | o---+  into  | o---+
    #     |  / /         |   | |  # <--- padding line
    #     o | |          |  / /
    #                    o | |
    add_padding_line = (len(text) > 2 and coldiff == -1 and
                        [x for (x, y) in edges if x + 1 < y])

    # fix_nodeline_tail says whether to rewrite
    #
    #     | | o | |        | | o | |
    #     | | |/ /         | | |/ /
    #     | o | |    into  | o / /   # <--- fixed nodeline tail
    #     | |/ /           | |/ /
    #     o | |            o | |
    fix_nodeline_tail = len(text) <= 2 and not add_padding_line

    # nodeline is the line containing the node character (typically o)
    nodeline = echars[:idx * 2]
    nodeline.extend([char, " "])

    nodeline.extend(
        _getnodelineedgestail(
            echars, idx, state['lastindex'], ncols, coldiff,
            state['lastcoldiff'], fix_nodeline_tail))

    # shift_interline is the line containing the non-vertical
    # edges between this entry and the next
    shift_interline = echars[:idx * 2]
    for i in xrange(2 + coldiff):
        shift_interline.append(' ')
    count = ncols - idx - 1
    if coldiff == -1:
        for i in xrange(count):
            shift_interline.extend(['/', ' '])
    elif coldiff == 0:
        shift_interline.extend(echars[(idx + 1) * 2:ncols * 2])
    else:
        for i in xrange(count):
            shift_interline.extend(['\\', ' '])

    # draw edges from the current node to its parents
    _drawedges(echars, edges, nodeline, shift_interline)

    # lines is the list of all graph lines to print
    lines = [nodeline]
    if add_padding_line:
        lines.append(_getpaddingline(echars, idx, ncols, edges))

    # If 'graphshorten' config, only draw shift_interline
    # when there is any non vertical flow in graph.
    if state['graphshorten']:
        if any(c in '\/' for c in shift_interline if c):
            lines.append(shift_interline)
    # Else, no 'graphshorten' config so draw shift_interline.
    else:
        lines.append(shift_interline)

    # make sure that there are as many graph lines as there are
    # log strings
    extra_interline = echars[:(ncols + coldiff) * 2]
    if len(lines) < len(text):
        while len(lines) < len(text):
            lines.append(extra_interline[:])

    _drawendinglines(lines, extra_interline, edgemap, seen)

    while len(text) < len(lines):
        text.append("")

    if any(len(char) > 1 for char in edgemap.values()):
        # limit drawing an edge to the first or last N lines of the current
        # section the rest of the edge is drawn like a parent line.
        parent = state['styles'][PARENT][-1:]
        def _drawgp(char, i):
            # should a grandparent character be drawn for this line?
            if len(char) < 2:
                return True
            num = int(char[:-1])
            # either skip first num lines or take last num lines, based on sign
            return -num <= i if num < 0 else (len(lines) - i) <= num
        for i, line in enumerate(lines):
            line[:] = [c[-1:] if _drawgp(c, i) else parent for c in line]
        edgemap.update(
            (e, (c if len(c) < 2 else parent)) for e, c in edgemap.items())

    # print lines
    indentation_level = max(ncols, ncols + coldiff)
    for (line, logstr) in zip(lines, text):
        ln = "%-*s %s" % (2 * indentation_level, "".join(line), logstr)
        ui.write(ln.rstrip() + '\n')

    # ... and start over
    state['lastcoldiff'] = coldiff
    state['lastindex'] = idx