view tests/test-debugcommands.t @ 29859:a1092e2d70a3

help: internals topic for wire protocol

The Mercurial wire protocol is under-documented. This includes a lack
of source docstrings and comments as well as pages on the official
wiki.

This patch adds the beginnings of "internals" documentation on the
wire protocol.

The documentation should have nearly complete coverage on the
lower-level parts of the protocol, such as the different transport
mechanims, how commands and arguments are sent, capabilities, and,
of course, the commands themselves.

As part of writing this documentation, I discovered a number of
deficiencies in the protocol and bugs in the implementation. I've
started sending patches for some of the issues. I hope to send a lot
more.

This patch starts with the scaffolding for a new internals page.

  $ cat << EOF >> $HGRCPATH
  > [format]
  > usegeneraldelta=yes
  > EOF

  $ hg init debugrevlog
  $ cd debugrevlog
  $ echo a > a
  $ hg ci -Am adda
  adding a
  $ hg debugrevlog -m
  format : 1
  flags  : inline, generaldelta
  
  revisions     :  1
      merges    :  0 ( 0.00%)
      normal    :  1 (100.00%)
  revisions     :  1
      full      :  1 (100.00%)
      deltas    :  0 ( 0.00%)
  revision size : 44
      full      : 44 (100.00%)
      deltas    :  0 ( 0.00%)
  
  avg chain length  : 0
  max chain length  : 0
  compression ratio : 0
  
  uncompressed data size (min/max/avg) : 43 / 43 / 43
  full revision size (min/max/avg)     : 44 / 44 / 44
  delta size (min/max/avg)             : 0 / 0 / 0

Test debugindex, with and without the --debug flag
  $ hg debugindex a
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       3   ....       0 b789fdd96dc2 000000000000 000000000000 (re)
  $ hg --debug debugindex a
     rev    offset  length  ..... linkrev nodeid                                   p1                                       p2 (re)
       0         0       3   ....       0 b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 (re)
  $ hg debugindex -f 1 a
     rev flag   offset   length     size  .....   link     p1     p2       nodeid (re)
       0 0000        0        3        2   ....      0     -1     -1 b789fdd96dc2 (re)
  $ hg --debug debugindex -f 1 a
     rev flag   offset   length     size  .....   link     p1     p2                                   nodeid (re)
       0 0000        0        3        2   ....      0     -1     -1 b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 (re)

debugdelta chain basic output

  $ hg debugdeltachain -m
      rev  chain# chainlen     prev   delta       size    rawsize  chainsize     ratio   lindist extradist extraratio
        0       1        1       -1    base         44         43         44   1.02326        44         0    0.00000

  $ hg debugdeltachain -m -T '{rev} {chainid} {chainlen}\n'
  0 1 1

  $ hg debugdeltachain -m -Tjson
  [
   {
    "chainid": 1,
    "chainlen": 1,
    "chainratio": 1.02325581395,
    "chainsize": 44,
    "compsize": 44,
    "deltatype": "base",
    "extradist": 0,
    "extraratio": 0.0,
    "lindist": 44,
    "prevrev": -1,
    "rev": 0,
    "uncompsize": 43
   }
  ]

Test max chain len
  $ cat >> $HGRCPATH << EOF
  > [format]
  > maxchainlen=4
  > EOF

  $ printf "This test checks if maxchainlen config value is respected also it can serve as basic test for debugrevlog -d <file>.\n" >> a
  $ hg ci -m a
  $ printf "b\n" >> a
  $ hg ci -m a
  $ printf "c\n" >> a
  $ hg ci -m a
  $ printf "d\n" >> a
  $ hg ci -m a
  $ printf "e\n" >> a
  $ hg ci -m a
  $ printf "f\n" >> a
  $ hg ci -m a
  $ printf 'g\n' >> a
  $ hg ci -m a
  $ printf 'h\n' >> a
  $ hg ci -m a
  $ hg debugrevlog -d a
  # rev p1rev p2rev start   end deltastart base   p1   p2 rawsize totalsize compression heads chainlen
      0    -1    -1     0   ???          0    0    0    0     ???      ????           ?     1        0 (glob)
      1     0    -1   ???   ???          0    0    0    0     ???      ????           ?     1        1 (glob)
      2     1    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        2 (glob)
      3     2    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        3 (glob)
      4     3    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        4 (glob)
      5     4    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        0 (glob)
      6     5    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        1 (glob)
      7     6    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        2 (glob)
      8     7    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        3 (glob)
  $ cd ..

Test internal debugstacktrace command

  $ cat > debugstacktrace.py << EOF
  > from mercurial.util import debugstacktrace, dst, sys
  > def f():
  >     dst('hello world')
  > def g():
  >     f()
  >     debugstacktrace(skip=-5, f=sys.stdout)
  > g()
  > EOF
  $ python debugstacktrace.py
  hello world at:
   debugstacktrace.py:7 in * (glob)
   debugstacktrace.py:5 in g
   debugstacktrace.py:3 in f
  stacktrace at:
   debugstacktrace.py:7 *in * (glob)
   debugstacktrace.py:6 *in g (glob)
   */util.py:* in debugstacktrace (glob)