add bundlerepo.py: a read-only repo that can use uncompressed bundles

The idea is to create a repo consisting of a normal local repository
plus all the changesets contained in a bundle.

The bundle needs to be uncompressed. A futur version could implement
the seeking through a compressed bundle.

mercurial/bundlerepo.py

@@ -0,0 +1,213 b''
+"""
+bundlerepo.py - repository class for viewing uncompressed bundles
+
+This provides a read-only repository interface to bundles as if
+they were part of the actual repository.
+
+Copyright 2006 Benoit Boissinot <[e-mail]>
+
+This software may be used and distributed according to the terms
+of the GNU General Public License, incorporated herein by reference.
+"""
+
+from node import *
+from i18n import gettext as _
+from demandload import demandload
+demandload(globals(), "util os struct")
+
+from changelog import changelog
+from manifest import manifest
+from filelog import filelog
+from localrepo import localrepository
+from revlog import *
+
+def getchunk(source):
+    """get a chunk from a group"""
+    d = source.read(4)
+    if not d:
+        return ""
+    l = struct.unpack(">l", d)[0]
+    if l <= 4:
+        return ""
+    d = source.read(l - 4)
+    if len(d) < l - 4:
+        raise util.Abort(_("premature EOF reading chunk"
+                           " (got %d bytes, expected %d)")
+                          % (len(d), l - 4))
+    return d
+
+class bundlerevlog(revlog):
+    def __init__(self, opener, indexfile, datafile, bundlefile,
+                 linkmapper=None):
+        # How it works:
+        # to retrieve a revision, we need to know the offset of
+        # the revision in the bundlefile (an opened file).
+        #
+        # We store this offset in the index (start), to differentiate a
+        # rev in the bundle and from a rev in the revlog, we check
+        # len(index[r]). If the tuple is bigger than 7, it is a bundle
+        # (it is bigger since we store the node to which the delta is)
+        #
+        revlog.__init__(self, opener, indexfile, datafile)
+        self.bundlefile = bundlefile
+        def genchunk():
+            while 1:
+                pos = bundlefile.tell()
+                chunk = getchunk(bundlefile)
+                if not chunk:
+                    break
+                yield chunk, pos + 4 # XXX struct.calcsize(">l") == 4
+        n = self.count()
+        prev = None
+        for chunk, start in genchunk():
+            size = len(chunk)
+            if size < 80:
+                raise util.Abort("invalid changegroup")
+            start += 80
+            size -= 80
+            node, p1, p2, cs = struct.unpack("20s20s20s20s", chunk[:80])
+            if node in self.nodemap:
+                prev = node
+                continue
+            for p in (p1, p2):
+                if not p in self.nodemap:
+                    raise RevlogError(_("unknown parent %s") % short(p1))
+            if linkmapper is None:
+                link = n
+            else:
+                link = linkmapper(cs)
+
+            if not prev:
+                prev = p1
+            # start, size, base is not used, link, p1, p2, delta ref
+            # warning: 
+            e = (start, size, None, link, p1, p2, node, prev)
+            self.index.append(e)
+            self.nodemap[node] = n
+            prev = node
+            n += 1
+
+    def bundle(self, rev):
+        """is rev from the bundle"""
+        if rev < 0:
+            return False
+        return len(self.index[rev]) > 7
+    def bundlebase(self, rev): return self.index[rev][7]
+    def chunk(self, rev):
+        # Warning: in case of bundle, the diff is against bundlebase,
+        # not against rev - 1
+        # XXX: could use some caching
+        if not self.bundle(rev):
+            return revlog.chunk(self, rev)
+        self.bundlefile.seek(self.start(rev))
+        return self.bundlefile.read(self.length(rev))
+
+    def revdiff(self, rev1, rev2):
+        """return or calculate a delta between two revisions"""
+        if self.bundle(rev1) and self.bundle(rev2):
+            # hot path for bundle
+            revb = self.rev(self.bundlebase(rev2))
+            if revb == rev1:
+                return self.chunk(rev2)
+        elif not self.bundle(rev1) and not self.bundle(rev2):
+            return revlog.chunk(self, rev1, rev2)
+
+        return self.diff(self.revision(self.node(rev1)),
+                         self.revision(self.node(rev2)))
+
+    def revision(self, node):
+        """return an uncompressed revision of a given"""
+        if node == nullid: return ""
+
+        text = None
+        chain = []
+        iter_node = node
+        rev = self.rev(iter_node)
+        # reconstruct the revision if it is from a changegroup
+        while self.bundle(rev):
+            if self.cache and self.cache[0] == iter_node:
+                text = self.cache[2]
+                break
+            chain.append(rev)
+            iter_node = self.bundlebase(rev)
+            rev = self.rev(iter_node)
+        if text is None:
+            text = revlog.revision(self, iter_node)
+
+        while chain:
+            delta = self.chunk(chain.pop())
+            text = self.patches(text, [delta])
+
+        p1, p2 = self.parents(node)
+        if node != hash(text, p1, p2):
+            raise RevlogError(_("integrity check failed on %s:%d")
+                          % (self.datafile, self.rev(node)))
+
+        self.cache = (node, rev, text)
+        return text
+
+    def addrevision(self, text, transaction, link, p1=None, p2=None, d=None):
+        raise NotImplementedError
+    def addgroup(self, revs, linkmapper, transaction, unique=0):
+        raise NotImplementedError
+    def strip(self, rev, minlink):
+        raise NotImplementedError
+    def checksize(self):
+        raise NotImplementedError
+
+class bundlechangelog(bundlerevlog, changelog):
+    def __init__(self, opener, bundlefile):
+        changelog.__init__(self, opener)
+        bundlerevlog.__init__(self, opener, "00changelog.i", "00changelog.d",
+                              bundlefile)
+
+class bundlemanifest(bundlerevlog, manifest):
+    def __init__(self, opener, bundlefile, linkmapper):
+        manifest.__init__(self, opener)
+        bundlerevlog.__init__(self, opener, self.indexfile, self.datafile,
+                              bundlefile, linkmapper)
+
+class bundlefilelog(bundlerevlog, filelog):
+    def __init__(self, opener, path, bundlefile, linkmapper):
+        filelog.__init__(self, opener, path)
+        bundlerevlog.__init__(self, opener, self.indexfile, self.datafile,
+                              bundlefile, linkmapper)
+
+class bundlerepository(localrepository):
+    def __init__(self, ui, path, bundlename):
+        localrepository.__init__(self, ui, path)
+        f = open(bundlename, "rb")
+        s = os.fstat(f.fileno())
+        self.bundlefile = f
+        header = self.bundlefile.read(4)
+        if header == "HG10":
+            raise util.Abort(_("%s: compressed bundle not supported")
+                             % bundlename)
+        elif header != "HG11":
+            raise util.Abort(_("%s: not a Mercurial bundle file") % bundlename)
+        self.changelog = bundlechangelog(self.opener, self.bundlefile)
+        self.manifest = bundlemanifest(self.opener, self.bundlefile,
+                                       self.changelog.rev)
+        # dict with the mapping 'filename' -> position in the bundle
+        self.bundlefilespos = {}
+        while 1:
+                f = getchunk(self.bundlefile)
+                if not f:
+                    break
+                self.bundlefilespos[f] = self.bundlefile.tell()
+                while getchunk(self.bundlefile):
+                    pass
+
+    def dev(self):
+        return -1
+
+    def file(self, f):
+        if f[0] == '/':
+            f = f[1:]
+        if f in self.bundlefilespos:
+            self.bundlefile.seek(self.bundlefilespos[f])
+            return bundlefilelog(self.opener, f, self.bundlefile,
+                                 self.changelog.rev)
+        else:
+            return filelog(self.opener, f)
+