view tests/test-wireproto-caching.t @ 46607:e9901d01d135

revlog: add a mechanism to verify expected file position before appending

If someone uses `hg debuglocks`, or some non-hg process writes to the .hg
directory without respecting the locks, or if the repo's on a networked
filesystem, it's possible for the revlog code to write out corrupted data.

The form of this corruption can vary depending on what data was written and how
that happened. We are in the "networked filesystem" case (though I've had users
also do this to themselves with the "`hg debuglocks`" scenario), and most often
see this with the changelog. What ends up happening is we produce two items
(let's call them rev1 and rev2) in the .i file that have the same linkrev,
baserev, and offset into the .d file, while the data in the .d file is appended
properly. rev2's compressed_size is accurate for rev2, but when we go to
decompress the data in the .d file, we use the offset that's recorded in the
index file, which is the same as rev1, and attempt to decompress
rev2.compressed_size bytes of rev1's data. This usually does not succeed. :)

When using inline data, this also fails, though I haven't investigated why too
closely. This shows up as a "patch decode" error. I believe what's happening
there is that we're basically ignoring the offset field, getting the data
properly, but since baserev != rev, it thinks this is a delta based on rev
(instead of a full text) and can't actually apply it as such.

For now, I'm going to make this an optional component and default it to entirely
off. I may increase the default severity of this in the future, once I've
enabled it for my users and we gain more experience with it. Luckily, most of my
users have a versioned filesystem and can roll back to before the corruption has
been written, it's just a hassle to do so and not everyone knows how (so it's a
support burden). Users on other filesystems will not have that luxury, and this
can cause them to have a corrupted repository that they are unlikely to know how
to resolve, and they'll see this as a data-loss event. Refusing to create the
corruption is a much better user experience.

This mechanism is not perfect. There may be false-negatives (racy writes that
are not detected). There should not be any false-positives (non-racy writes that
are detected as such). This is not a mechanism that makes putting a repo on a
networked filesystem "safe" or "supported", just *less* likely to cause
corruption.

Differential Revision: https://phab.mercurial-scm.org/D9952

  $ . $TESTDIR/wireprotohelpers.sh
  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > blackbox =
  > [blackbox]
  > track = simplecache
  > EOF
  $ hg init server
  $ enablehttpv2 server
  $ cd server
  $ cat >> .hg/hgrc << EOF
  > [extensions]
  > simplecache = $TESTDIR/wireprotosimplecache.py
  > EOF

  $ echo a0 > a
  $ echo b0 > b
  $ hg -q commit -A -m 'commit 0'
  $ echo a1 > a
  $ hg commit -m 'commit 1'
  $ echo b1 > b
  $ hg commit -m 'commit 2'
  $ echo a2 > a
  $ echo b2 > b
  $ hg commit -m 'commit 3'

  $ hg log -G -T '{rev}:{node} {desc}'
  @  3:50590a86f3ff5d1e9a1624a7a6957884565cc8e8 commit 3
  |
  o  2:4d01eda50c6ac5f7e89cbe1880143a32f559c302 commit 2
  |
  o  1:4432d83626e8a98655f062ec1f2a43b07f7fbbb0 commit 1
  |
  o  0:3390ef850073fbc2f0dfff2244342c8e9229013a commit 0
  

  $ hg --debug debugindex -m
     rev linkrev nodeid                                   p1                                       p2
       0       0 992f4779029a3df8d0666d00bb924f69634e2641 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000
       1       1 a988fb43583e871d1ed5750ee074c6d840bbbfc8 992f4779029a3df8d0666d00bb924f69634e2641 0000000000000000000000000000000000000000
       2       2 a8853dafacfca6fc807055a660d8b835141a3bb4 a988fb43583e871d1ed5750ee074c6d840bbbfc8 0000000000000000000000000000000000000000
       3       3 3fe11dfbb13645782b0addafbe75a87c210ffddc a8853dafacfca6fc807055a660d8b835141a3bb4 0000000000000000000000000000000000000000

  $ hg serve -p $HGPORT -d --pid-file hg.pid -E error.log
  $ cat hg.pid > $DAEMON_PIDS

Performing the same request should result in same result, with 2nd response
coming from cache.

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x99\x2f\x47\x79\x02\x9a\x3d\xf8\xd0\x66\x6d\x00\xbb\x92\x4f\x69\x63\x4e\x26\x41']
  >     tree eval:b''
  >     fields eval:[b'parents']
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'node': b'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
      b'parents': [
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    }
  ]

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x99\x2f\x47\x79\x02\x9a\x3d\xf8\xd0\x66\x6d\x00\xbb\x92\x4f\x69\x63\x4e\x26\x41']
  >     tree eval:b''
  >     fields eval:[b'parents']
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'node': b'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
      b'parents': [
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    }
  ]

Sending different request doesn't yield cache hit.

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x99\x2f\x47\x79\x02\x9a\x3d\xf8\xd0\x66\x6d\x00\xbb\x92\x4f\x69\x63\x4e\x26\x41', b'\xa9\x88\xfb\x43\x58\x3e\x87\x1d\x1e\xd5\x75\x0e\xe0\x74\xc6\xd8\x40\xbb\xbf\xc8']
  >     tree eval:b''
  >     fields eval:[b'parents']
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 2
    },
    {
      b'node': b'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
      b'parents': [
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    },
    {
      b'node': b'\xa9\x88\xfbCX>\x87\x1d\x1e\xd5u\x0e\xe0t\xc6\xd8@\xbb\xbf\xc8',
      b'parents': [
        b'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    }
  ]

  $ cat .hg/blackbox.log
  *> cacher constructed for manifestdata (glob)
  *> cache miss for 47abb8efa5f01b8964d74917793ad2464db0fa2c (glob)
  *> storing cache entry for 47abb8efa5f01b8964d74917793ad2464db0fa2c (glob)
  *> cacher constructed for manifestdata (glob)
  *> cache hit for 47abb8efa5f01b8964d74917793ad2464db0fa2c (glob)
  *> cacher constructed for manifestdata (glob)
  *> cache miss for 37326a83e9843f15161fce9d1e92d06b795d5e8e (glob)
  *> storing cache entry for 37326a83e9843f15161fce9d1e92d06b795d5e8e (glob)

  $ cat error.log

  $ killdaemons.py
  $ rm .hg/blackbox.log

Try with object caching mode

  $ cat >> .hg/hgrc << EOF
  > [simplecache]
  > cacheobjects = true
  > EOF

  $ hg serve -p $HGPORT -d --pid-file hg.pid -E error.log
  $ cat hg.pid > $DAEMON_PIDS

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x99\x2f\x47\x79\x02\x9a\x3d\xf8\xd0\x66\x6d\x00\xbb\x92\x4f\x69\x63\x4e\x26\x41']
  >     tree eval:b''
  >     fields eval:[b'parents']
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'node': b'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
      b'parents': [
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    }
  ]

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\x99\x2f\x47\x79\x02\x9a\x3d\xf8\xd0\x66\x6d\x00\xbb\x92\x4f\x69\x63\x4e\x26\x41']
  >     tree eval:b''
  >     fields eval:[b'parents']
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'node': b'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
      b'parents': [
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    }
  ]

  $ cat .hg/blackbox.log
  *> cacher constructed for manifestdata (glob)
  *> cache miss for 47abb8efa5f01b8964d74917793ad2464db0fa2c (glob)
  *> storing cache entry for 47abb8efa5f01b8964d74917793ad2464db0fa2c (glob)
  *> cacher constructed for manifestdata (glob)
  *> cache hit for 47abb8efa5f01b8964d74917793ad2464db0fa2c (glob)

  $ cat error.log

  $ killdaemons.py
  $ rm .hg/blackbox.log

A non-cacheable command does not instantiate cacher

  $ hg serve -p $HGPORT -d --pid-file hg.pid -E error.log
  $ cat hg.pid > $DAEMON_PIDS
  $ sendhttpv2peer << EOF
  > command capabilities
  > EOF
  creating http peer for wire protocol version 2
  sending capabilities command
  response: gen[
    {
      b'commands': {
        b'branchmap': {
          b'args': {},
          b'permissions': [
            b'pull'
          ]
        },
        b'capabilities': {
          b'args': {},
          b'permissions': [
            b'pull'
          ]
        },
        b'changesetdata': {
          b'args': {
            b'fields': {
              b'default': set([]),
              b'required': False,
              b'type': b'set',
              b'validvalues': set([
                b'bookmarks',
                b'parents',
                b'phase',
                b'revision'
              ])
            },
            b'revisions': {
              b'required': True,
              b'type': b'list'
            }
          },
          b'permissions': [
            b'pull'
          ]
        },
        b'filedata': {
          b'args': {
            b'fields': {
              b'default': set([]),
              b'required': False,
              b'type': b'set',
              b'validvalues': set([
                b'linknode',
                b'parents',
                b'revision'
              ])
            },
            b'haveparents': {
              b'default': False,
              b'required': False,
              b'type': b'bool'
            },
            b'nodes': {
              b'required': True,
              b'type': b'list'
            },
            b'path': {
              b'required': True,
              b'type': b'bytes'
            }
          },
          b'permissions': [
            b'pull'
          ]
        },
        b'filesdata': {
          b'args': {
            b'fields': {
              b'default': set([]),
              b'required': False,
              b'type': b'set',
              b'validvalues': set([
                b'firstchangeset',
                b'linknode',
                b'parents',
                b'revision'
              ])
            },
            b'haveparents': {
              b'default': False,
              b'required': False,
              b'type': b'bool'
            },
            b'pathfilter': {
              b'default': None,
              b'required': False,
              b'type': b'dict'
            },
            b'revisions': {
              b'required': True,
              b'type': b'list'
            }
          },
          b'permissions': [
            b'pull'
          ],
          b'recommendedbatchsize': 50000
        },
        b'heads': {
          b'args': {
            b'publiconly': {
              b'default': False,
              b'required': False,
              b'type': b'bool'
            }
          },
          b'permissions': [
            b'pull'
          ]
        },
        b'known': {
          b'args': {
            b'nodes': {
              b'default': [],
              b'required': False,
              b'type': b'list'
            }
          },
          b'permissions': [
            b'pull'
          ]
        },
        b'listkeys': {
          b'args': {
            b'namespace': {
              b'required': True,
              b'type': b'bytes'
            }
          },
          b'permissions': [
            b'pull'
          ]
        },
        b'lookup': {
          b'args': {
            b'key': {
              b'required': True,
              b'type': b'bytes'
            }
          },
          b'permissions': [
            b'pull'
          ]
        },
        b'manifestdata': {
          b'args': {
            b'fields': {
              b'default': set([]),
              b'required': False,
              b'type': b'set',
              b'validvalues': set([
                b'parents',
                b'revision'
              ])
            },
            b'haveparents': {
              b'default': False,
              b'required': False,
              b'type': b'bool'
            },
            b'nodes': {
              b'required': True,
              b'type': b'list'
            },
            b'tree': {
              b'required': True,
              b'type': b'bytes'
            }
          },
          b'permissions': [
            b'pull'
          ],
          b'recommendedbatchsize': 100000
        },
        b'pushkey': {
          b'args': {
            b'key': {
              b'required': True,
              b'type': b'bytes'
            },
            b'namespace': {
              b'required': True,
              b'type': b'bytes'
            },
            b'new': {
              b'required': True,
              b'type': b'bytes'
            },
            b'old': {
              b'required': True,
              b'type': b'bytes'
            }
          },
          b'permissions': [
            b'push'
          ]
        },
        b'rawstorefiledata': {
          b'args': {
            b'files': {
              b'required': True,
              b'type': b'list'
            },
            b'pathfilter': {
              b'default': None,
              b'required': False,
              b'type': b'list'
            }
          },
          b'permissions': [
            b'pull'
          ]
        }
      },
      b'framingmediatypes': [
        b'application/mercurial-exp-framing-0006'
      ],
      b'pathfilterprefixes': set([
        b'path:',
        b'rootfilesin:'
      ]),
      b'rawrepoformats': [
        b'generaldelta',
        b'revlogv1',
        b'sparserevlog'
      ]
    }
  ]

  $ test -f .hg/blackbox.log
  [1]

An error is not cached

  $ sendhttpv2peer << EOF
  > command manifestdata
  >     nodes eval:[b'\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa']
  >     tree eval:b''
  >     fields eval:[b'parents']
  > EOF
  creating http peer for wire protocol version 2
  sending manifestdata command
  abort: unknown node: \xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa (esc)
  [255]

  $ cat .hg/blackbox.log
  *> cacher constructed for manifestdata (glob)
  *> cache miss for 2cba2a7d0d1575fea2fe68f597e97a7c2ac2f705 (glob)
  *> cacher exiting due to error (glob)

  $ killdaemons.py
  $ rm .hg/blackbox.log