view tests/test-pager.t @ 39764:e4e881572382

localrepo: iteratively derive local repository type

This commit implements the dynamic local repository type derivation
that was explained in the recent commit
bfeab472e3c0 "localrepo: create new function for instantiating a local
repo object."

Instead of a static localrepository class/type which must be customized
after construction, we now dynamically construct a type by building up
base classes/types to represent specific repository interfaces.

Conceptually, the end state is similar to what was happening when
various extensions would monkeypatch the __class__ of newly-constructed
repo instances. However, the approach is inverted. Instead of making
the instance then customizing it, we do the customization up front
by influencing the behavior of the type then we instantiate that
custom type.

This approach gives us much more flexibility. For example, we can
use completely separate classes for implementing different aspects
of the repository. For example, we could have one class representing
revlog-based file storage and another representing non-revlog based
file storage. When then choose which implementation to use based on
the presence of repo requirements.

A concern with this approach is that it creates a lot more types
and complexity and that complexity adds overhead. Yes, it is true that
this approach will result in more types being created. Yes, this is
more complicated than traditional "instantiate a static type." However,
I believe the alternatives to supporting alternate storage backends
are just as complicated. (Before I arrived at this solution, I had
patches storing factory functions on local repo instances for e.g.
constructing a file storage instance. We ended up having a handful
of these. And this was logically identical to assigning custom
methods. Since we were logically changing the type of the instance,
I figured it would be better to just use specialized types instead
of introducing levels of abstraction at run-time.)

On the performance front, I don't believe that having N base classes
has any significant performance overhead compared to just a single base
class. Intuition says that Python will need to iterate the base classes
to find an attribute. However, CPython caches method lookups: as long as
the __class__ or MRO isn't changing, method attribute lookup should be
constant time after first access. And non-method attributes are stored
in __dict__, of which there is only 1 per object, so the number of
base classes for __dict__ is irrelevant.

Anyway, this commit splits up the monolithic completelocalrepository
interface into sub-interfaces: 1 for file storage and 1 representing
everything else.

We've taught ``makelocalrepository()`` to call a series of factory
functions which will produce types implementing specific interfaces.
It then calls type() to create a new type from the built-up list of
base types.

This commit should be considered a start and not the end state. I
suspect we'll hit a number of problems as we start to implement
alternate storage backends:

* Passing custom arguments to __init__ and setting custom attributes
  on __dict__.
* Customizing the set of interfaces that are needed. e.g. the
  "readonly" intent could translate to not requesting an interface
  providing methods related to writing.
* More ergonomic way for extensions to insert themselves so their
  callbacks aren't unconditionally called.
* Wanting to modify vfs instances, other arguments passed to __init__.

That being said, this code is usable in its current state and I'm
convinced future commits will demonstrate the value in this approach.

Differential Revision: https://phab.mercurial-scm.org/D4642

  $ cat >> fakepager.py <<EOF
  > import sys
  > printed = False
  > for line in sys.stdin:
  >     sys.stdout.write('paged! %r\n' % line)
  >     printed = True
  > if not printed:
  >     sys.stdout.write('paged empty output!\n')
  > EOF

Enable ui.formatted because pager won't fire without it, and set up
pager and tell it to use our fake pager that lets us see when the
pager was running.
  $ cat >> $HGRCPATH <<EOF
  > [ui]
  > formatted = yes
  > color = no
  > [pager]
  > pager = "$PYTHON" $TESTTMP/fakepager.py
  > EOF

  $ hg init repo
  $ cd repo
  $ echo a >> a
  $ hg add a
  $ hg ci -m 'add a'
  $ for x in `"$PYTHON" $TESTDIR/seq.py 1 10`; do
  >   echo a $x >> a
  >   hg ci -m "modify a $x"
  > done

By default diff and log are paged, but id is not:

  $ hg diff -c 2 --pager=yes
  paged! 'diff -r f4be7687d414 -r bce265549556 a\n'
  paged! '--- a/a\tThu Jan 01 00:00:00 1970 +0000\n'
  paged! '+++ b/a\tThu Jan 01 00:00:00 1970 +0000\n'
  paged! '@@ -1,2 +1,3 @@\n'
  paged! ' a\n'
  paged! ' a 1\n'
  paged! '+a 2\n'

  $ hg log --limit 2
  paged! 'changeset:   10:46106edeeb38\n'
  paged! 'tag:         tip\n'
  paged! 'user:        test\n'
  paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
  paged! 'summary:     modify a 10\n'
  paged! '\n'
  paged! 'changeset:   9:6dd8ea7dd621\n'
  paged! 'user:        test\n'
  paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
  paged! 'summary:     modify a 9\n'
  paged! '\n'

  $ hg id
  46106edeeb38 tip

We can control the pager from the config

  $ hg log --limit 1 --config 'ui.paginate=False'
  changeset:   10:46106edeeb38
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     modify a 10
  
  $ hg log --limit 1 --config 'ui.paginate=0'
  changeset:   10:46106edeeb38
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     modify a 10
  
  $ hg log --limit 1 --config 'ui.paginate=1'
  paged! 'changeset:   10:46106edeeb38\n'
  paged! 'tag:         tip\n'
  paged! 'user:        test\n'
  paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
  paged! 'summary:     modify a 10\n'
  paged! '\n'

explicit --pager=on should take precedence over other configurations
(issue5580)

  $ cat >> $HGRCPATH <<EOF
  > [ui]
  > paginate = false
  > EOF
  $ hg log --limit 1 --pager=on
  paged! 'changeset:   10:46106edeeb38\n'
  paged! 'tag:         tip\n'
  paged! 'user:        test\n'
  paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
  paged! 'summary:     modify a 10\n'
  paged! '\n'

  $ cat >> $HGRCPATH <<EOF
  > [ui]
  > # true is default value of ui.paginate
  > paginate = true
  > EOF
  $ hg log --limit 1 --pager=off
  changeset:   10:46106edeeb38
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     modify a 10
  

We can enable the pager on id:

BROKEN: should be paged
  $ hg --config pager.attend-id=yes id
  46106edeeb38 tip

Setting attend-$COMMAND to a false value works, even with pager in
core:
  $ hg --config pager.attend-diff=no diff -c 2
  diff -r f4be7687d414 -r bce265549556 a
  --- a/a	Thu Jan 01 00:00:00 1970 +0000
  +++ b/a	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,2 +1,3 @@
   a
   a 1
  +a 2

Command aliases should have same behavior as main command

  $ hg history --limit 2
  paged! 'changeset:   10:46106edeeb38\n'
  paged! 'tag:         tip\n'
  paged! 'user:        test\n'
  paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
  paged! 'summary:     modify a 10\n'
  paged! '\n'
  paged! 'changeset:   9:6dd8ea7dd621\n'
  paged! 'user:        test\n'
  paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
  paged! 'summary:     modify a 9\n'
  paged! '\n'

Abbreviated command alias should also be paged

  $ hg hist -l 1
  paged! 'changeset:   10:46106edeeb38\n'
  paged! 'tag:         tip\n'
  paged! 'user:        test\n'
  paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
  paged! 'summary:     modify a 10\n'
  paged! '\n'

Attend for an abbreviated command does not work

  $ hg --config pager.attend-ident=true ident
  46106edeeb38 tip

  $ hg --config extensions.pager= --config pager.attend-ident=true ident
  46106edeeb38 tip

Pager should not start if stdout is not a tty.

  $ hg log -l1 -q --config ui.formatted=False
  10:46106edeeb38

Pager should be disabled if pager.pager is empty (otherwise the output would
be silently lost.)

  $ hg log -l1 -q --config pager.pager=
  10:46106edeeb38

Pager with color enabled allows colors to come through by default,
even though stdout is no longer a tty.
  $ cat >> $HGRCPATH <<EOF
  > [ui]
  > color = always
  > [color]
  > mode = ansi
  > EOF
  $ hg log --limit 3
  paged! '\x1b[0;33mchangeset:   10:46106edeeb38\x1b[0m\n'
  paged! 'tag:         tip\n'
  paged! 'user:        test\n'
  paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
  paged! 'summary:     modify a 10\n'
  paged! '\n'
  paged! '\x1b[0;33mchangeset:   9:6dd8ea7dd621\x1b[0m\n'
  paged! 'user:        test\n'
  paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
  paged! 'summary:     modify a 9\n'
  paged! '\n'
  paged! '\x1b[0;33mchangeset:   8:cff05a6312fe\x1b[0m\n'
  paged! 'user:        test\n'
  paged! 'date:        Thu Jan 01 00:00:00 1970 +0000\n'
  paged! 'summary:     modify a 8\n'
  paged! '\n'

#if no-chg
An invalid pager command name is reported sensibly if we don't have to
use shell=True in the subprocess call:
  $ hg log --limit 3 --config pager.pager=this-command-better-never-exist
  missing pager command 'this-command-better-never-exist', skipping pager
  \x1b[0;33mchangeset:   10:46106edeeb38\x1b[0m (esc)
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     modify a 10
  
  \x1b[0;33mchangeset:   9:6dd8ea7dd621\x1b[0m (esc)
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     modify a 9
  
  \x1b[0;33mchangeset:   8:cff05a6312fe\x1b[0m (esc)
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     modify a 8
  
#endif

A complicated pager command gets worse behavior. Bonus points if you can
improve this.
  $ hg log --limit 3 \
  >   --config pager.pager='this-command-better-never-exist --seriously' \
  >  2>/dev/null || true

Pager works with shell aliases.

  $ cat >> $HGRCPATH <<EOF
  > [alias]
  > echoa = !echo a
  > EOF

  $ hg echoa
  a
BROKEN: should be paged
  $ hg --config pager.attend-echoa=yes echoa
  a

Pager works with hg aliases including environment variables.

  $ cat >> $HGRCPATH <<'EOF'
  > [alias]
  > printa = log -T "$A\n" -r 0
  > EOF

  $ A=1 hg --config pager.attend-printa=yes printa
  paged! '1\n'
  $ A=2 hg --config pager.attend-printa=yes printa
  paged! '2\n'

Something that's explicitly attended is still not paginated if the
pager is globally set to off using a flag:
  $ A=2 hg --config pager.attend-printa=yes printa --pager=no
  2

Pager should not override the exit code of other commands

  $ cat >> $TESTTMP/fortytwo.py <<'EOF'
  > from mercurial import commands, registrar
  > cmdtable = {}
  > command = registrar.command(cmdtable)
  > @command(b'fortytwo', [], b'fortytwo', norepo=True)
  > def fortytwo(ui, *opts):
  >     ui.write(b'42\n')
  >     return 42
  > EOF

  $ cat >> $HGRCPATH <<'EOF'
  > [extensions]
  > fortytwo = $TESTTMP/fortytwo.py
  > EOF

  $ hg fortytwo --pager=on
  paged! '42\n'
  [42]

A command that asks for paging using ui.pager() directly works:
  $ hg blame a
  paged! ' 0: a\n'
  paged! ' 1: a 1\n'
  paged! ' 2: a 2\n'
  paged! ' 3: a 3\n'
  paged! ' 4: a 4\n'
  paged! ' 5: a 5\n'
  paged! ' 6: a 6\n'
  paged! ' 7: a 7\n'
  paged! ' 8: a 8\n'
  paged! ' 9: a 9\n'
  paged! '10: a 10\n'
but not with HGPLAIN
  $ HGPLAIN=1 hg blame a
   0: a
   1: a 1
   2: a 2
   3: a 3
   4: a 4
   5: a 5
   6: a 6
   7: a 7
   8: a 8
   9: a 9
  10: a 10
explicit flags work too:
  $ hg blame --pager=no a
   0: a
   1: a 1
   2: a 2
   3: a 3
   4: a 4
   5: a 5
   6: a 6
   7: a 7
   8: a 8
   9: a 9
  10: a 10

A command with --output option:

  $ hg cat -r0 a
  paged! 'a\n'
  $ hg cat -r0 a --output=-
  paged! 'a\n'
  $ hg cat -r0 a --output=out

  $ hg export -r0
  paged! '# HG changeset patch\n'
  paged! '# User test\n'
  paged! '# Date 0 0\n'
  paged! '#      Thu Jan 01 00:00:00 1970 +0000\n'
  paged! '# Node ID 1f0dee641bb7258c56bd60e93edfa2405381c41e\n'
  paged! '# Parent  0000000000000000000000000000000000000000\n'
  paged! 'add a\n'
  paged! '\n'
  paged! '\x1b[0;1mdiff -r 000000000000 -r 1f0dee641bb7 a\x1b[0m\n'
  paged! '\x1b[0;31;1m--- /dev/null\tThu Jan 01 00:00:00 1970 +0000\x1b[0m\n'
  paged! '\x1b[0;32;1m+++ b/a\tThu Jan 01 00:00:00 1970 +0000\x1b[0m\n'
  paged! '\x1b[0;35m@@ -0,0 +1,1 @@\x1b[0m\n'
  paged! '\x1b[0;32m+a\x1b[0m\n'
  $ hg export -r0 -o -
  paged! '# HG changeset patch\n'
  paged! '# User test\n'
  paged! '# Date 0 0\n'
  paged! '#      Thu Jan 01 00:00:00 1970 +0000\n'
  paged! '# Node ID 1f0dee641bb7258c56bd60e93edfa2405381c41e\n'
  paged! '# Parent  0000000000000000000000000000000000000000\n'
  paged! 'add a\n'
  paged! '\n'
  paged! '\x1b[0;1mdiff -r 000000000000 -r 1f0dee641bb7 a\x1b[0m\n'
  paged! '\x1b[0;31;1m--- /dev/null\tThu Jan 01 00:00:00 1970 +0000\x1b[0m\n'
  paged! '\x1b[0;32;1m+++ b/a\tThu Jan 01 00:00:00 1970 +0000\x1b[0m\n'
  paged! '\x1b[0;35m@@ -0,0 +1,1 @@\x1b[0m\n'
  paged! '\x1b[0;32m+a\x1b[0m\n'
  $ hg export -r0 -o out

  $ rm out

Put annotate in the ignore list for pager:
  $ cat >> $HGRCPATH <<EOF
  > [pager]
  > ignore = annotate
  > EOF
  $ hg blame a
   0: a
   1: a 1
   2: a 2
   3: a 3
   4: a 4
   5: a 5
   6: a 6
   7: a 7
   8: a 8
   9: a 9
  10: a 10

During pushbuffer, pager should not start:
  $ cat > $TESTTMP/pushbufferpager.py <<EOF
  > def uisetup(ui):
  >     ui.pushbuffer()
  >     ui.pager(b'mycmd')
  >     ui.write(b'content\n')
  >     ui.write(ui.popbuffer())
  > EOF

  $ echo append >> a
  $ hg --config extensions.pushbuffer=$TESTTMP/pushbufferpager.py status --color=off
  content
  paged! 'M a\n'

Environment variables like LESS and LV are set automatically:
  $ cat > $TESTTMP/printlesslv.py <<EOF
  > from __future__ import absolute_import
  > import os
  > import sys
  > sys.stdin.read()
  > for name in ['LESS', 'LV']:
  >     sys.stdout.write(('%s=%s\n') % (name, os.environ.get(name, '-')))
  > sys.stdout.flush()
  > EOF

  $ cat >> $HGRCPATH <<EOF
  > [alias]
  > noop = log -r 0 -T ''
  > [ui]
  > formatted=1
  > [pager]
  > pager = "$PYTHON" $TESTTMP/printlesslv.py
  > EOF
  $ unset LESS
  $ unset LV
  $ hg noop --pager=on
  LESS=FRX
  LV=-c
  $ LESS=EFGH hg noop --pager=on
  LESS=EFGH
  LV=-c