tests/test-remotefilelog-datapack.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, print_function

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

import silenttestrunner

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

class datapacktestsbase(object):
    def __init__(self, datapackreader, paramsavailable):
        self.datapackreader = datapackreader
        self.paramsavailable = paramsavailable

    def setUp(self):
        self.tempdirs = []

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

    def makeTempDir(self):
        tempdir = pycompat.bytestr(tempfile.mkdtemp())
        self.tempdirs.append(tempdir)
        return 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, packdir=None):
        if revisions is None:
            revisions = [(b"filename", self.getFakeHash(), nullid, b"content")]

        if packdir is None:
            packdir = self.makeTempDir()

        packer = datapack.mutabledatapack(uimod.ui(), packdir, version=2)

        for args in revisions:
            filename, node, base, content = args[0:4]
            # meta is optional
            meta = None
            if len(args) > 4:
                meta = args[4]
            packer.add(filename, node, base, content, metadata=meta)

        path = packer.close()
        return self.datapackreader(path)

    def _testAddSingle(self, content):
        """Test putting a simple blob into a pack and reading it out.
        """
        filename = b"foo"
        node = self.getHash(content)

        revisions = [(filename, node, nullid, content)]
        pack = self.createPack(revisions)
        if self.paramsavailable:
            self.assertEqual(pack.params.fanoutprefix,
                             basepack.SMALLFANOUTPREFIX)

        chain = pack.getdeltachain(filename, node)
        self.assertEqual(content, chain[0][4])

    def testAddSingle(self):
        self._testAddSingle(b'')

    def testAddSingleEmpty(self):
        self._testAddSingle(b'abcdef')

    def testAddMultiple(self):
        """Test putting multiple unrelated blobs into a pack and reading them
        out.
        """
        revisions = []
        for i in range(10):
            filename = b"foo%d" % i
            content = b"abcdef%d" % i
            node = self.getHash(content)
            revisions.append((filename, node, self.getFakeHash(), content))

        pack = self.createPack(revisions)

        for filename, node, base, content in revisions:
            entry = pack.getdelta(filename, node)
            self.assertEqual((content, filename, base, {}), entry)

            chain = pack.getdeltachain(filename, node)
            self.assertEqual(content, chain[0][4])

    def testAddDeltas(self):
        """Test putting multiple delta blobs into a pack and read the chain.
        """
        revisions = []
        filename = b"foo"
        lastnode = nullid
        for i in range(10):
            content = b"abcdef%d" % i
            node = self.getHash(content)
            revisions.append((filename, node, lastnode, content))
            lastnode = node

        pack = self.createPack(revisions)

        entry = pack.getdelta(filename, revisions[0][1])
        realvalue = (revisions[0][3], filename, revisions[0][2], {})
        self.assertEqual(entry, realvalue)

        # Test that the chain for the final entry has all the others
        chain = pack.getdeltachain(filename, node)
        for i in range(10):
            content = b"abcdef%d" % i
            self.assertEqual(content, chain[-i - 1][4])

    def testPackMany(self):
        """Pack many related and unrelated objects.
        """
        # Build a random pack file
        revisions = []
        blobs = {}
        random.seed(0)
        for i in range(100):
            filename = b"filename-%d" % i
            filerevs = []
            for j in range(random.randint(1, 100)):
                content = b"content-%d" % j
                node = self.getHash(content)
                lastnode = nullid
                if len(filerevs) > 0:
                    lastnode = filerevs[random.randint(0, len(filerevs) - 1)]
                filerevs.append(node)
                blobs[(filename, node, lastnode)] = content
                revisions.append((filename, node, lastnode, content))

        pack = self.createPack(revisions)

        # Verify the pack contents
        for (filename, node, lastnode), content in sorted(blobs.items()):
            chain = pack.getdeltachain(filename, node)
            for entry in chain:
                expectedcontent = blobs[(entry[0], entry[1], entry[3])]
                self.assertEqual(entry[4], expectedcontent)

    def testPackMetadata(self):
        revisions = []
        for i in range(100):
            filename = b'%d.txt' % i
            content = b'put-something-here \n' * i
            node = self.getHash(content)
            meta = {constants.METAKEYFLAG: i ** 4,
                    constants.METAKEYSIZE: len(content),
                    b'Z': b'random_string',
                    b'_': b'\0' * i}
            revisions.append((filename, node, nullid, content, meta))
        pack = self.createPack(revisions)
        for name, node, x, content, origmeta in revisions:
            parsedmeta = pack.getmeta(name, node)
            # flag == 0 should be optimized out
            if origmeta[constants.METAKEYFLAG] == 0:
                del origmeta[constants.METAKEYFLAG]
            self.assertEqual(parsedmeta, origmeta)

    def testGetMissing(self):
        """Test the getmissing() api.
        """
        revisions = []
        filename = b"foo"
        lastnode = nullid
        for i in range(10):
            content = b"abcdef%d" % i
            node = self.getHash(content)
            revisions.append((filename, node, lastnode, content))
            lastnode = node

        pack = self.createPack(revisions)

        missing = pack.getmissing([(b"foo", revisions[0][1])])
        self.assertFalse(missing)

        missing = pack.getmissing([(b"foo", revisions[0][1]),
                                   (b"foo", revisions[1][1])])
        self.assertFalse(missing)

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

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

        try:
            pack.add(b'filename', nullid, b'contents')
            self.assertTrue(False, "datapack.add should throw")
        except RuntimeError:
            pass

    def testBadVersionThrows(self):
        pack = self.createPack()
        path = pack.path + b'.datapack'
        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 = self.datapackreader(pack.path)
            self.assertTrue(False, "bad version number should have thrown")
        except RuntimeError:
            pass

    def testMissingDeltabase(self):
        fakenode = self.getFakeHash()
        revisions = [(b"filename", fakenode, self.getFakeHash(), b"content")]
        pack = self.createPack(revisions)
        chain = pack.getdeltachain(b"filename", fakenode)
        self.assertEqual(len(chain), 1)

    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."""
        revisions = []
        blobs = {}
        total = basepack.SMALLFANOUTCUTOFF + 1
        for i in pycompat.xrange(total):
            filename = b"filename-%d" % i
            content = filename
            node = self.getHash(content)
            blobs[(filename, node)] = content
            revisions.append((filename, node, nullid, content))

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

        for (filename, node), content in blobs.items():
            actualcontent = pack.getdeltachain(filename, node)[0][4]
            self.assertEqual(actualcontent, content)

    def testPacksCache(self):
        """Test that we remember the most recent packs while fetching the delta
        chain."""

        packdir = self.makeTempDir()
        deltachains = []

        numpacks = 10
        revisionsperpack = 100

        for i in range(numpacks):
            chain = []
            revision = (b'%d' % i, self.getFakeHash(), nullid, b"content")

            for _ in range(revisionsperpack):
                chain.append(revision)
                revision = (
                    b'%d' % i,
                    self.getFakeHash(),
                    revision[1],
                    self.getFakeHash()
                )

            self.createPack(chain, packdir)
            deltachains.append(chain)

        class testdatapackstore(datapack.datapackstore):
            # Ensures that we are not keeping everything in the cache.
            DEFAULTCACHESIZE = numpacks // 2

        store = testdatapackstore(uimod.ui(), packdir)

        random.shuffle(deltachains)
        for randomchain in deltachains:
            revision = random.choice(randomchain)
            chain = store.getdeltachain(revision[0], revision[1])

            mostrecentpack = next(iter(store.packs), None)
            self.assertEqual(
                mostrecentpack.getdeltachain(revision[0], revision[1]),
                chain
            )

            self.assertEqual(randomchain.index(revision) + 1, len(chain))

    # perf test off by default since it's slow
    def _testIndexPerf(self):
        random.seed(0)
        print("Multi-get perf test")
        packsizes = [
            100,
            10000,
            100000,
            500000,
            1000000,
            3000000,
        ]
        lookupsizes = [
            10,
            100,
            1000,
            10000,
            100000,
            1000000,
        ]
        for packsize in packsizes:
            revisions = []
            for i in pycompat.xrange(packsize):
                filename = b"filename-%d" % i
                content = b"content-%d" % i
                node = self.getHash(content)
                revisions.append((filename, node, nullid, content))

            path = self.createPack(revisions).path

            # Perf of large multi-get
            import gc
            gc.disable()
            pack = self.datapackreader(path)
            for lookupsize in lookupsizes:
                if lookupsize > packsize:
                    continue
                random.shuffle(revisions)
                findnodes = [(rev[0], rev[1]) for rev in revisions]

                start = time.time()
                pack.getmissing(findnodes[:lookupsize])
                elapsed = time.time() - start
                print ("%s pack %d lookups = %0.04f" %
                       (('%d' % packsize).rjust(7),
                        ('%d' % lookupsize).rjust(7),
                        elapsed))

            print("")
            gc.enable()

        # The perf test is meant to produce output, so we always fail the test
        # so the user sees the output.
        raise RuntimeError("perf test always fails")

class datapacktests(datapacktestsbase, unittest.TestCase):
    def __init__(self, *args, **kwargs):
        datapacktestsbase.__init__(self, datapack.datapack, True)
        unittest.TestCase.__init__(self, *args, **kwargs)

# TODO:
# datapack store:
# - getmissing
# - GC two packs into one

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