mercurial/manifest.py

Implement revlogng.

revlogng results in smaller indexes, can address larger data files, and
supports flags and version numbers.

By default the original revlog format is used.  To use the new format,
use the following .hgrc field:

[revlog]
# format choices are 0 (classic revlog format) and 1 revlogng
format=1

# manifest.py - manifest revision class for mercurial
#
# Copyright 2005 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

import struct
from revlog import *
from i18n import gettext as _
from demandload import *
demandload(globals(), "bisect array")

class manifest(revlog):
    def __init__(self, opener, defversion=0):
        self.mapcache = None
        self.listcache = None
        revlog.__init__(self, opener, "00manifest.i", "00manifest.d",
                        defversion)

    def read(self, node):
        if node == nullid: return {} # don't upset local cache
        if self.mapcache and self.mapcache[0] == node:
            return self.mapcache[1]
        text = self.revision(node)
        map = {}
        flag = {}
        self.listcache = array.array('c', text)
        lines = text.splitlines(1)
        for l in lines:
            (f, n) = l.split('\0')
            map[f] = bin(n[:40])
            flag[f] = (n[40:-1] == "x")
        self.mapcache = (node, map, flag)
        return map

    def readflags(self, node):
        if node == nullid: return {} # don't upset local cache
        if not self.mapcache or self.mapcache[0] != node:
            self.read(node)
        return self.mapcache[2]

    def diff(self, a, b):
        return mdiff.textdiff(str(a), str(b))

    def add(self, map, flags, transaction, link, p1=None, p2=None,
            changed=None):

        # returns a tuple (start, end).  If the string is found
        # m[start:end] are the line containing that string.  If start == end
        # the string was not found and they indicate the proper sorted 
        # insertion point.  This was taken from bisect_left, and modified
        # to find line start/end as it goes along.
        #
        # m should be a buffer or a string
        # s is a string
        #
        def manifestsearch(m, s, lo=0, hi=None):
            def advance(i, c):
                while i < lenm and m[i] != c:
                    i += 1
                return i
            lenm = len(m)
            if not hi:
                hi = lenm
            while lo < hi:
                mid = (lo + hi) // 2
                start = mid
                while start > 0 and m[start-1] != '\n':
                    start -= 1
                end = advance(start, '\0')
                if m[start:end] < s:
                    # we know that after the null there are 40 bytes of sha1
                    # this translates to the bisect lo = mid + 1
                    lo = advance(end + 40, '\n') + 1
                else:
                    # this translates to the bisect hi = mid
                    hi = start
            end = advance(lo, '\0')
            found = m[lo:end]
            if cmp(s, found) == 0: 
                # we know that after the null there are 40 bytes of sha1
                end = advance(end + 40, '\n')
                return (lo, end+1)
            else:
                return (lo, lo)

        # apply the changes collected during the bisect loop to our addlist
        # return a delta suitable for addrevision
        def addlistdelta(addlist, x):
            # start from the bottom up
            # so changes to the offsets don't mess things up.
            i = len(x)
            while i > 0:
                i -= 1
                start = x[i][0]
                end = x[i][1]
                if x[i][2]:
                    addlist[start:end] = array.array('c', x[i][2])
                else:
                    del addlist[start:end]
            return "".join([struct.pack(">lll", d[0], d[1], len(d[2])) + d[2] \
                            for d in x ])

        # if we're using the listcache, make sure it is valid and
        # parented by the same node we're diffing against
        if not changed or not self.listcache or not p1 or \
               self.mapcache[0] != p1:
            files = map.keys()
            files.sort()

            # if this is changed to support newlines in filenames,
            # be sure to check the templates/ dir again (especially *-raw.tmpl)
            text = ["%s\000%s%s\n" %
                            (f, hex(map[f]), flags[f] and "x" or '')
                            for f in files]
            self.listcache = array.array('c', "".join(text))
            cachedelta = None
        else:
            addlist = self.listcache

            # combine the changed lists into one list for sorting
            work = [[x, 0] for x in changed[0]]
            work[len(work):] = [[x, 1] for x in changed[1]]
            work.sort()

            delta = []
            dstart = None
            dend = None
            dline = [""]
            start = 0
            # zero copy representation of addlist as a buffer
            addbuf = buffer(addlist)

            # start with a readonly loop that finds the offset of
            # each line and creates the deltas
            for w in work:
                f = w[0]
                # bs will either be the index of the item or the insert point
                start, end = manifestsearch(addbuf, f, start)
                if w[1] == 0:
                    l = "%s\000%s%s\n" % (f, hex(map[f]),
                                          flags[f] and "x" or '')
                else:
                    l = ""
                if start == end and w[1] == 1:
                    # item we want to delete was not found, error out
                    raise AssertionError(
                            _("failed to remove %s from manifest\n") % f)
                if dstart != None and dstart <= start and dend >= start:
                    if dend < end:
                        dend = end
                    if l:
                        dline.append(l)
                else:
                    if dstart != None:
                        delta.append([dstart, dend, "".join(dline)])
                    dstart = start
                    dend = end
                    dline = [l]

            if dstart != None:
                delta.append([dstart, dend, "".join(dline)])
            # apply the delta to the addlist, and get a delta for addrevision
            cachedelta = addlistdelta(addlist, delta)

            # the delta is only valid if we've been processing the tip revision
            if self.mapcache[0] != self.tip():
                cachedelta = None
            self.listcache = addlist

        n = self.addrevision(buffer(self.listcache), transaction, link, p1,  \
                             p2, cachedelta)
        self.mapcache = (n, map, flags)

        return n