view tests/test-eol-hook.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

Test the EOL hook

  $ hg init main
  $ cat > main/.hg/hgrc <<EOF
  > [hooks]
  > pretxnchangegroup = python:hgext.eol.hook
  > EOF
  $ hg clone main fork
  updating to branch default
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd fork

Create repo
  $ cat > .hgeol <<EOF
  > [patterns]
  > mixed.txt = BIN
  > crlf.txt = CRLF
  > **.txt = native
  > EOF
  $ hg add .hgeol
  $ hg commit -m 'Commit .hgeol'

  $ printf "first\nsecond\nthird\n" > a.txt
  $ hg add a.txt
  $ hg commit -m 'LF a.txt'
  $ hg push ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files

  $ printf "first\r\nsecond\r\nthird\n" > a.txt
  $ hg commit -m 'CRLF a.txt'
  $ hg push ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  error: pretxnchangegroup hook failed: end-of-line check failed:
    a.txt in a8ee6548cd86 should not have CRLF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    a.txt in a8ee6548cd86 should not have CRLF line endings
  [255]

  $ printf "first\nsecond\nthird\n" > a.txt
  $ hg commit -m 'LF a.txt (fixed)'
  $ hg push ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files

  $ printf "first\nsecond\nthird\n" > crlf.txt
  $ hg add crlf.txt
  $ hg commit -m 'LF crlf.txt'
  $ hg push ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  error: pretxnchangegroup hook failed: end-of-line check failed:
    crlf.txt in 004ba2132725 should not have LF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    crlf.txt in 004ba2132725 should not have LF line endings
  [255]

  $ printf "first\r\nsecond\r\nthird\r\n" > crlf.txt
  $ hg commit -m 'CRLF crlf.txt (fixed)'
  $ hg push ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files

  $ printf "first\r\nsecond" > b.txt
  $ hg add b.txt
  $ hg commit -m 'CRLF b.txt'
  $ hg push ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  error: pretxnchangegroup hook failed: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  [255]

  $ hg up -r -2
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ printf "some\nother\nfile" > c.txt
  $ hg add c.txt
  $ hg commit -m "LF c.txt, b.txt doesn't exist here"
  created new head
  $ hg push -f ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files (+1 heads)
  error: pretxnchangegroup hook failed: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  [255]

Test checkheadshook alias

  $ cat > ../main/.hg/hgrc <<EOF
  > [hooks]
  > pretxnchangegroup = python:hgext.eol.checkheadshook
  > EOF
  $ hg push -f ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files (+1 heads)
  error: pretxnchangegroup hook failed: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  [255]

We can fix the head and push again

  $ hg up 6
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ printf "first\nsecond" > b.txt
  $ hg ci -m "remove CRLF from b.txt"
  $ hg push -f ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files (+1 heads)
  $ hg -R ../main rollback
  repository tip rolled back to revision 5 (undo push)

Test it still fails with checkallhook

  $ cat > ../main/.hg/hgrc <<EOF
  > [hooks]
  > pretxnchangegroup = python:hgext.eol.checkallhook
  > EOF
  $ hg push -f ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files (+1 heads)
  error: pretxnchangegroup hook failed: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
  [255]

But we can push the clean head

  $ hg push -r7 -f ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files

Test multiple files/revisions output

  $ printf "another\r\nbad\r\none" > d.txt
  $ hg add d.txt
  $ hg ci -m "add d.txt"
  $ hg push -f ../main
  pushing to ../main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files (+1 heads)
  error: pretxnchangegroup hook failed: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
    d.txt in a7040e68714f should not have CRLF line endings
  transaction abort!
  rollback completed
  abort: end-of-line check failed:
    b.txt in fbcf9b1025f5 should not have CRLF line endings
    d.txt in a7040e68714f should not have CRLF line endings
  [255]

  $ cd ..