view mercurial/dagparser.py @ 51492:2e8a88e5809f

branchcache: stop writing more branchcache file on disk than needed

Before this change, we were unconditionally writing a branchmap file for the
filter level passed to `update_disk`. This is actually counter productive if no
update were needed for this filter level. In many case, the branch cache for a
filter level is identical to its parent "subset" and it is better to simply
keep the subset update and reuse it every time instead of having to do identical
work for similar subset.

So we change the `update_disk` method to only write a file when that filter
level differ from its parent. This removes many cases where identical files were
written, requiring multiple boring update in the test suite.

The only notable changes is the change to `test-strip-branch-cache.t`, this
case was checking a scenario that no longer reproduce the bug as writing less
branchmap file result in less stalled cache on disk.

Strictly speaking, we could create a more convoluted scenario that create a
similar issue. However the next changeset would also cover that scenario so we
directly updated that test case to a "no longer buggy" state.

# dagparser.py - parser and generator for concise description of DAGs
#
# Copyright 2010 Peter Arrenbrecht <[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.


import re
import string

from .i18n import _
from . import (
    error,
    pycompat,
)
from .utils import stringutil


def parsedag(desc):
    '''parses a DAG from a concise textual description; generates events

    "+n" is a linear run of n nodes based on the current default parent
    "." is a single node based on the current default parent
    "$" resets the default parent to -1 (implied at the start);
        otherwise the default parent is always the last node created
    "<p" sets the default parent to the backref p
    "*p" is a fork at parent p, where p is a backref
    "*p1/p2/.../pn" is a merge of parents p1..pn, where the pi are backrefs
    "/p2/.../pn" is a merge of the preceding node and p2..pn
    ":name" defines a label for the preceding node; labels can be redefined
    "@text" emits an annotation event for text
    "!command" emits an action event for the current node
    "!!my command\n" is like "!", but to the end of the line
    "#...\n" is a comment up to the end of the line

    Whitespace between the above elements is ignored.

    A backref is either
     * a number n, which references the node curr-n, where curr is the current
       node, or
     * the name of a label you placed earlier using ":name", or
     * empty to denote the default parent.

    All string valued-elements are either strictly alphanumeric, or must
    be enclosed in double quotes ("..."), with "\" as escape character.

    Generates sequence of

      ('n', (id, [parentids])) for node creation
      ('l', (id, labelname)) for labels on nodes
      ('a', text) for annotations
      ('c', command) for actions (!)
      ('C', command) for line actions (!!)

    Examples
    --------

    Example of a complex graph (output not shown for brevity):

        >>> len(list(parsedag(b"""
        ...
        ... +3         # 3 nodes in linear run
        ... :forkhere  # a label for the last of the 3 nodes from above
        ... +5         # 5 more nodes on one branch
        ... :mergethis # label again
        ... <forkhere  # set default parent to labeled fork node
        ... +10        # 10 more nodes on a parallel branch
        ... @stable    # following nodes will be annotated as "stable"
        ... +5         # 5 nodes in stable
        ... !addfile   # custom command; could trigger new file in next node
        ... +2         # two more nodes
        ... /mergethis # merge last node with labeled node
        ... +4         # 4 more nodes descending from merge node
        ...
        ... """)))
        34

    Empty list:

        >>> list(parsedag(b""))
        []

    A simple linear run:

        >>> list(parsedag(b"+3"))
        [('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [1]))]

    Some non-standard ways to define such runs:

        >>> list(parsedag(b"+1+2"))
        [('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [1]))]

        >>> list(parsedag(b"+1*1*"))
        [('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [1]))]

        >>> list(parsedag(b"*"))
        [('n', (0, [-1]))]

        >>> list(parsedag(b"..."))
        [('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [1]))]

    A fork and a join, using numeric back references:

        >>> list(parsedag(b"+2*2*/2"))
        [('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [0])), ('n', (3, [2, 1]))]

        >>> list(parsedag(b"+2<2+1/2"))
        [('n', (0, [-1])), ('n', (1, [0])), ('n', (2, [0])), ('n', (3, [2, 1]))]

    Placing a label:

        >>> list(parsedag(b"+1 :mylabel +1"))
        [('n', (0, [-1])), ('l', (0, 'mylabel')), ('n', (1, [0]))]

    An empty label (silly, really):

        >>> list(parsedag(b"+1:+1"))
        [('n', (0, [-1])), ('l', (0, '')), ('n', (1, [0]))]

    Fork and join, but with labels instead of numeric back references:

        >>> list(parsedag(b"+1:f +1:p2 *f */p2"))
        [('n', (0, [-1])), ('l', (0, 'f')), ('n', (1, [0])), ('l', (1, 'p2')),
         ('n', (2, [0])), ('n', (3, [2, 1]))]

        >>> list(parsedag(b"+1:f +1:p2 <f +1 /p2"))
        [('n', (0, [-1])), ('l', (0, 'f')), ('n', (1, [0])), ('l', (1, 'p2')),
         ('n', (2, [0])), ('n', (3, [2, 1]))]

    Restarting from the root:

        >>> list(parsedag(b"+1 $ +1"))
        [('n', (0, [-1])), ('n', (1, [-1]))]

    Annotations, which are meant to introduce sticky state for subsequent nodes:

        >>> list(parsedag(b"+1 @ann +1"))
        [('n', (0, [-1])), ('a', 'ann'), ('n', (1, [0]))]

        >>> list(parsedag(b'+1 @"my annotation" +1'))
        [('n', (0, [-1])), ('a', 'my annotation'), ('n', (1, [0]))]

    Commands, which are meant to operate on the most recently created node:

        >>> list(parsedag(b"+1 !cmd +1"))
        [('n', (0, [-1])), ('c', 'cmd'), ('n', (1, [0]))]

        >>> list(parsedag(b'+1 !"my command" +1'))
        [('n', (0, [-1])), ('c', 'my command'), ('n', (1, [0]))]

        >>> list(parsedag(b'+1 !!my command line\\n +1'))
        [('n', (0, [-1])), ('C', 'my command line'), ('n', (1, [0]))]

    Comments, which extend to the end of the line:

        >>> list(parsedag(b'+1 # comment\\n+1'))
        [('n', (0, [-1])), ('n', (1, [0]))]

    Error:

        >>> try: list(parsedag(b'+1 bad'))
        ... except Exception as e: print(pycompat.sysstr(bytes(e)))
        invalid character in dag description: bad...

    '''
    if not desc:
        return

    # pytype: disable=wrong-arg-types
    wordchars = pycompat.bytestr(string.ascii_letters + string.digits)
    # pytype: enable=wrong-arg-types

    labels = {}
    p1 = -1
    r = 0

    def resolve(ref):
        if not ref:
            return p1
        # pytype: disable=wrong-arg-types
        elif ref[0] in pycompat.bytestr(string.digits):
            # pytype: enable=wrong-arg-types
            return r - int(ref)
        else:
            return labels[ref]

    chiter = pycompat.iterbytestr(desc)

    def nextch():
        return next(chiter, b'\0')

    def nextrun(c, allow):
        s = b''
        while c in allow:
            s += c
            c = nextch()
        return c, s

    def nextdelimited(c, limit, escape):
        s = b''
        while c != limit:
            if c == escape:
                c = nextch()
            s += c
            c = nextch()
        return nextch(), s

    def nextstring(c):
        if c == b'"':
            return nextdelimited(nextch(), b'"', b'\\')
        else:
            return nextrun(c, wordchars)

    c = nextch()
    while c != b'\0':
        # pytype: disable=wrong-arg-types
        while c in pycompat.bytestr(string.whitespace):
            # pytype: enable=wrong-arg-types
            c = nextch()
        if c == b'.':
            yield b'n', (r, [p1])
            p1 = r
            r += 1
            c = nextch()
        elif c == b'+':
            # pytype: disable=wrong-arg-types
            c, digs = nextrun(nextch(), pycompat.bytestr(string.digits))
            # pytype: enable=wrong-arg-types
            n = int(digs)
            for i in range(0, n):
                yield b'n', (r, [p1])
                p1 = r
                r += 1
        elif c in b'*/':
            if c == b'*':
                c = nextch()
            c, pref = nextstring(c)
            prefs = [pref]
            while c == b'/':
                c, pref = nextstring(nextch())
                prefs.append(pref)
            ps = [resolve(ref) for ref in prefs]
            yield b'n', (r, ps)
            p1 = r
            r += 1
        elif c == b'<':
            c, ref = nextstring(nextch())
            p1 = resolve(ref)
        elif c == b':':
            c, name = nextstring(nextch())
            labels[name] = p1
            yield b'l', (p1, name)
        elif c == b'@':
            c, text = nextstring(nextch())
            yield b'a', text
        elif c == b'!':
            c = nextch()
            if c == b'!':
                cmd = b''
                c = nextch()
                while c not in b'\n\r\0':
                    cmd += c
                    c = nextch()
                yield b'C', cmd
            else:
                c, cmd = nextstring(c)
                yield b'c', cmd
        elif c == b'#':
            while c not in b'\n\r\0':
                c = nextch()
        elif c == b'$':
            p1 = -1
            c = nextch()
        elif c == b'\0':
            return  # in case it was preceded by whitespace
        else:
            s = b''
            i = 0
            while c != b'\0' and i < 10:
                s += c
                i += 1
                c = nextch()
            raise error.Abort(
                _(b'invalid character in dag description: %s...') % s
            )


def dagtextlines(
    events,
    addspaces=True,
    wraplabels=False,
    wrapannotations=False,
    wrapcommands=False,
    wrapnonlinear=False,
    usedots=False,
    maxlinewidth=70,
):
    '''generates single lines for dagtext()'''

    def wrapstring(text):
        if re.match(b"^[0-9a-z]*$", text):
            return text
        return b'"' + text.replace(b'\\', b'\\\\').replace(b'"', b'\"') + b'"'

    def gen():
        labels = {}
        run = 0
        wantr = 0
        needroot = False
        for kind, data in events:
            if kind == b'n':
                r, ps = data

                # sanity check
                if r != wantr:
                    raise error.Abort(_(b"expected id %i, got %i") % (wantr, r))
                if not ps:
                    ps = [-1]
                else:
                    for p in ps:
                        if p >= r:
                            raise error.Abort(
                                _(
                                    b"parent id %i is larger than "
                                    b"current id %i"
                                )
                                % (p, r)
                            )
                wantr += 1

                # new root?
                p1 = r - 1
                if len(ps) == 1 and ps[0] == -1:
                    if needroot:
                        if run:
                            yield b'+%d' % run
                            run = 0
                        if wrapnonlinear:
                            yield b'\n'
                        yield b'$'
                        p1 = -1
                    else:
                        needroot = True
                if len(ps) == 1 and ps[0] == p1:
                    if usedots:
                        yield b"."
                    else:
                        run += 1
                else:
                    if run:
                        yield b'+%d' % run
                        run = 0
                    if wrapnonlinear:
                        yield b'\n'
                    prefs = []
                    for p in ps:
                        if p == p1:
                            prefs.append(b'')
                        elif p in labels:
                            prefs.append(labels[p])
                        else:
                            prefs.append(b'%d' % (r - p))
                    yield b'*' + b'/'.join(prefs)
            else:
                if run:
                    yield b'+%d' % run
                    run = 0
                if kind == b'l':
                    rid, name = data
                    labels[rid] = name
                    yield b':' + name
                    if wraplabels:
                        yield b'\n'
                elif kind == b'c':
                    yield b'!' + wrapstring(data)
                    if wrapcommands:
                        yield b'\n'
                elif kind == b'C':
                    yield b'!!' + data
                    yield b'\n'
                elif kind == b'a':
                    if wrapannotations:
                        yield b'\n'
                    yield b'@' + wrapstring(data)
                elif kind == b'#':
                    yield b'#' + data
                    yield b'\n'
                else:
                    raise error.Abort(
                        _(b"invalid event type in dag: ('%s', '%s')")
                        % (
                            stringutil.escapestr(kind),
                            stringutil.escapestr(data),
                        )
                    )
        if run:
            yield b'+%d' % run

    line = b''
    for part in gen():
        if part == b'\n':
            if line:
                yield line
                line = b''
        else:
            if len(line) + len(part) >= maxlinewidth:
                yield line
                line = b''
            elif addspaces and line and part != b'.':
                line += b' '
            line += part
    if line:
        yield line


def dagtext(
    dag,
    addspaces=True,
    wraplabels=False,
    wrapannotations=False,
    wrapcommands=False,
    wrapnonlinear=False,
    usedots=False,
    maxlinewidth=70,
):
    """generates lines of a textual representation for a dag event stream

    events should generate what parsedag() does, so:

      ('n', (id, [parentids])) for node creation
      ('l', (id, labelname)) for labels on nodes
      ('a', text) for annotations
      ('c', text) for commands
      ('C', text) for line commands ('!!')
      ('#', text) for comment lines

    Parent nodes must come before child nodes.

    Examples
    --------

    Linear run:

        >>> dagtext([(b'n', (0, [-1])), (b'n', (1, [0]))])
        '+2'

    Two roots:

        >>> dagtext([(b'n', (0, [-1])), (b'n', (1, [-1]))])
        '+1 $ +1'

    Fork and join:

        >>> dagtext([(b'n', (0, [-1])), (b'n', (1, [0])), (b'n', (2, [0])),
        ...          (b'n', (3, [2, 1]))])
        '+2 *2 */2'

    Fork and join with labels:

        >>> dagtext([(b'n', (0, [-1])), (b'l', (0, b'f')), (b'n', (1, [0])),
        ...          (b'l', (1, b'p2')), (b'n', (2, [0])), (b'n', (3, [2, 1]))])
        '+1 :f +1 :p2 *f */p2'

    Annotations:

        >>> dagtext([(b'n', (0, [-1])), (b'a', b'ann'), (b'n', (1, [0]))])
        '+1 @ann +1'

        >>> dagtext([(b'n', (0, [-1])),
        ...          (b'a', b'my annotation'),
        ...          (b'n', (1, [0]))])
        '+1 @"my annotation" +1'

    Commands:

        >>> dagtext([(b'n', (0, [-1])), (b'c', b'cmd'), (b'n', (1, [0]))])
        '+1 !cmd +1'

        >>> dagtext([(b'n', (0, [-1])),
        ...          (b'c', b'my command'),
        ...          (b'n', (1, [0]))])
        '+1 !"my command" +1'

        >>> dagtext([(b'n', (0, [-1])),
        ...          (b'C', b'my command line'),
        ...          (b'n', (1, [0]))])
        '+1 !!my command line\\n+1'

    Comments:

        >>> dagtext([(b'n', (0, [-1])), (b'#', b' comment'), (b'n', (1, [0]))])
        '+1 # comment\\n+1'

        >>> dagtext([])
        ''

    Combining parsedag and dagtext:

        >>> dagtext(parsedag(b'+1 :f +1 :p2 *f */p2'))
        '+1 :f +1 :p2 *f */p2'

    """
    return b"\n".join(
        dagtextlines(
            dag,
            addspaces,
            wraplabels,
            wrapannotations,
            wrapcommands,
            wrapnonlinear,
            usedots,
            maxlinewidth,
        )
    )