tests/test-remotefilelog-histpack.py

commit: improve the files field of changelog for merges

Currently, the files list of merge commits repeats all the deletions
(either actual deletions, or files that got renamed) that happened
between base and p2 of the merge. If p2 is the main branch, the list
can easily be much bigger than the change being merged.

This results in various problems worth improving:
- changelog is bigger than necessary
- `hg log directory` lists many unrelated merge commits, and `hg log
  -v -r commit` frequently fills multiple screens worth of files
- it possibly slows down adjustlinkrev, by forcing it to read more
  manifests, and that function can certainly be a bottleneck
- the server side of pulls can waste a lot of time simply opening the
  filelogs for pointless files (the constant factors for opening even
  a tiny filelog is apparently pretty bad)

So stop listing such files as described in the code.  Impacted merge
commits and their descendants get a different hash than they would
have without this. This doesn't seem problematic, except for
convert. The previous commit helped with that in the hg->hg case (but
if you do svn->hg twice from scratch, hashes can still change).

The rest of the description is numbers. I don't have much to report,
because recreating the files list of existing repositories is not
easy:
- debugupgradeformat and bundle/unbundle don't recreate the list
- export/import tends to choke quickly applying patches or on
  description that contain diffs,
- merge commits from the convert extension don't have the right files
  list for reasons orthogonal to the current commit
- replaying the merge with hg update/hg merge/hg revert --all/hg
  commit can end up failing in hg revert
- I wasn't sure that using debugsetparents + debugrebuilddirstate
  would really build the right thing

I measured commit time before and after this change, in a case with no
files filtered out, several files filtered out (no difference) and 5k
files filtered out (+1% time).

Recreating the 100 more recent merges in a private repo, the
concatenated uncompressed files lists goes from 1.12MB to
0.52MB. Excluding 3 merges that are not representative, then the size
goes from 570k to 15k.
I converted part of mozilla-central, and observed file list shrinking
quite a bit too, starting at the very first merge, 733641d9feaf, going
from 550 files to 10 files (although they have relatively few merges,
so they probably wouldn't care).

Differential Revision: https://phab.mercurial-scm.org/D6613

#!/usr/bin/env python
from __future__ import absolute_import

import hashlib
import os
import random
import shutil
import stat
import struct
import sys
import tempfile
import unittest

import silenttestrunner

from mercurial.node import nullid
from mercurial import (
    pycompat,
    ui as uimod,
)
# Load the local remotefilelog, not the system one
sys.path[0:0] = [os.path.join(os.path.dirname(__file__), '..')]
from hgext.remotefilelog import (
    basepack,
    historypack,
)

class histpacktests(unittest.TestCase):
    def setUp(self):
        self.tempdirs = []

    def tearDown(self):
        for d in self.tempdirs:
            shutil.rmtree(d)

    def makeTempDir(self):
        tempdir = tempfile.mkdtemp()
        self.tempdirs.append(tempdir)
        return pycompat.fsencode(tempdir)

    def getHash(self, content):
        return hashlib.sha1(content).digest()

    def getFakeHash(self):
        return b''.join(pycompat.bytechr(random.randint(0, 255))
                        for _ in range(20))

    def createPack(self, revisions=None):
        """Creates and returns a historypack containing the specified revisions.

        `revisions` is a list of tuples, where each tuple contains a filanem,
        node, p1node, p2node, and linknode.
        """
        if revisions is None:
            revisions = [(b"filename", self.getFakeHash(), nullid, nullid,
                          self.getFakeHash(), None)]

        packdir = pycompat.fsencode(self.makeTempDir())
        packer = historypack.mutablehistorypack(uimod.ui(), packdir,
                                                version=2)

        for filename, node, p1, p2, linknode, copyfrom in revisions:
            packer.add(filename, node, p1, p2, linknode, copyfrom)

        path = packer.close()
        return historypack.historypack(path)

    def testAddSingle(self):
        """Test putting a single entry into a pack and reading it out.
        """
        filename = b"foo"
        node = self.getFakeHash()
        p1 = self.getFakeHash()
        p2 = self.getFakeHash()
        linknode = self.getFakeHash()

        revisions = [(filename, node, p1, p2, linknode, None)]
        pack = self.createPack(revisions)

        actual = pack.getancestors(filename, node)[node]
        self.assertEqual(p1, actual[0])
        self.assertEqual(p2, actual[1])
        self.assertEqual(linknode, actual[2])

    def testAddMultiple(self):
        """Test putting multiple unrelated revisions into a pack and reading
        them out.
        """
        revisions = []
        for i in range(10):
            filename = b"foo-%d" % i
            node = self.getFakeHash()
            p1 = self.getFakeHash()
            p2 = self.getFakeHash()
            linknode = self.getFakeHash()
            revisions.append((filename, node, p1, p2, linknode, None))

        pack = self.createPack(revisions)

        for filename, node, p1, p2, linknode, copyfrom in revisions:
            actual = pack.getancestors(filename, node)[node]
            self.assertEqual(p1, actual[0])
            self.assertEqual(p2, actual[1])
            self.assertEqual(linknode, actual[2])
            self.assertEqual(copyfrom, actual[3])

    def testAddAncestorChain(self):
        """Test putting multiple revisions in into a pack and read the ancestor
        chain.
        """
        revisions = []
        filename = b"foo"
        lastnode = nullid
        for i in range(10):
            node = self.getFakeHash()
            revisions.append((filename, node, lastnode, nullid, nullid, None))
            lastnode = node

        # revisions must be added in topological order, newest first
        revisions = list(reversed(revisions))
        pack = self.createPack(revisions)

        # Test that the chain has all the entries
        ancestors = pack.getancestors(revisions[0][0], revisions[0][1])
        for filename, node, p1, p2, linknode, copyfrom in revisions:
            ap1, ap2, alinknode, acopyfrom = ancestors[node]
            self.assertEqual(ap1, p1)
            self.assertEqual(ap2, p2)
            self.assertEqual(alinknode, linknode)
            self.assertEqual(acopyfrom, copyfrom)

    def testPackMany(self):
        """Pack many related and unrelated ancestors.
        """
        # Build a random pack file
        allentries = {}
        ancestorcounts = {}
        revisions = []
        random.seed(0)
        for i in range(100):
            filename = b"filename-%d" % i
            entries = []
            p2 = nullid
            linknode = nullid
            for j in range(random.randint(1, 100)):
                node = self.getFakeHash()
                p1 = nullid
                if len(entries) > 0:
                    p1 = entries[random.randint(0, len(entries) - 1)]
                entries.append(node)
                revisions.append((filename, node, p1, p2, linknode, None))
                allentries[(filename, node)] = (p1, p2, linknode)
                if p1 == nullid:
                    ancestorcounts[(filename, node)] = 1
                else:
                    newcount = ancestorcounts[(filename, p1)] + 1
                    ancestorcounts[(filename, node)] = newcount

        # Must add file entries in reverse topological order
        revisions = list(reversed(revisions))
        pack = self.createPack(revisions)

        # Verify the pack contents
        for (filename, node) in allentries:
            ancestors = pack.getancestors(filename, node)
            self.assertEqual(ancestorcounts[(filename, node)],
                             len(ancestors))
            for anode, (ap1, ap2, alinknode, copyfrom) in ancestors.items():
                ep1, ep2, elinknode = allentries[(filename, anode)]
                self.assertEqual(ap1, ep1)
                self.assertEqual(ap2, ep2)
                self.assertEqual(alinknode, elinknode)
                self.assertEqual(copyfrom, None)

    def testGetNodeInfo(self):
        revisions = []
        filename = b"foo"
        lastnode = nullid
        for i in range(10):
            node = self.getFakeHash()
            revisions.append((filename, node, lastnode, nullid, nullid, None))
            lastnode = node

        pack = self.createPack(revisions)

        # Test that getnodeinfo returns the expected results
        for filename, node, p1, p2, linknode, copyfrom in revisions:
            ap1, ap2, alinknode, acopyfrom = pack.getnodeinfo(filename, node)
            self.assertEqual(ap1, p1)
            self.assertEqual(ap2, p2)
            self.assertEqual(alinknode, linknode)
            self.assertEqual(acopyfrom, copyfrom)

    def testGetMissing(self):
        """Test the getmissing() api.
        """
        revisions = []
        filename = b"foo"
        for i in range(10):
            node = self.getFakeHash()
            p1 = self.getFakeHash()
            p2 = self.getFakeHash()
            linknode = self.getFakeHash()
            revisions.append((filename, node, p1, p2, linknode, None))

        pack = self.createPack(revisions)

        missing = pack.getmissing([(filename, revisions[0][1])])
        self.assertFalse(missing)

        missing = pack.getmissing([(filename, revisions[0][1]),
                                   (filename, revisions[1][1])])
        self.assertFalse(missing)

        fakenode = self.getFakeHash()
        missing = pack.getmissing([(filename, revisions[0][1]),
                                   (filename, fakenode)])
        self.assertEqual(missing, [(filename, fakenode)])

        # Test getmissing on a non-existant filename
        missing = pack.getmissing([(b"bar", fakenode)])
        self.assertEqual(missing, [(b"bar", fakenode)])

    def testAddThrows(self):
        pack = self.createPack()

        try:
            pack.add(b'filename', nullid, nullid, nullid, nullid, None)
            self.assertTrue(False, "historypack.add should throw")
        except RuntimeError:
            pass

    def testBadVersionThrows(self):
        pack = self.createPack()
        path = pack.path + b'.histpack'
        with open(path, 'rb') as f:
            raw = f.read()
        raw = struct.pack('!B', 255) + raw[1:]
        os.chmod(path, os.stat(path).st_mode | stat.S_IWRITE)
        with open(path, 'wb+') as f:
            f.write(raw)

        try:
            pack = historypack.historypack(pack.path)
            self.assertTrue(False, "bad version number should have thrown")
        except RuntimeError:
            pass

    def testLargePack(self):
        """Test creating and reading from a large pack with over X entries.
        This causes it to use a 2^16 fanout table instead."""
        total = basepack.SMALLFANOUTCUTOFF + 1
        revisions = []
        for i in pycompat.xrange(total):
            filename = b"foo-%d" % i
            node = self.getFakeHash()
            p1 = self.getFakeHash()
            p2 = self.getFakeHash()
            linknode = self.getFakeHash()
            revisions.append((filename, node, p1, p2, linknode, None))

        pack = self.createPack(revisions)
        self.assertEqual(pack.params.fanoutprefix, basepack.LARGEFANOUTPREFIX)

        for filename, node, p1, p2, linknode, copyfrom in revisions:
            actual = pack.getancestors(filename, node)[node]
            self.assertEqual(p1, actual[0])
            self.assertEqual(p2, actual[1])
            self.assertEqual(linknode, actual[2])
            self.assertEqual(copyfrom, actual[3])
# TODO:
# histpack store:
# - repack two packs into one

if __name__ == '__main__':
    if pycompat.iswindows:
        sys.exit(80)    # Skip on Windows
    silenttestrunner.main(__name__)