view tests/test-resolve.t @ 26457:7e81305092a0

demandimport: replace more references to _demandmod instances

_demandmod instances may be referenced by multiple importing modules.
Before this patch, the _demandmod instance only maintained a reference
to its first consumer when using the "from X import Y" syntax. This is
because we only created a single _demandmod instance (attached to the
parent X module). If multiple modules A and B performed
"from X import Y", we'd produce a single _demandmod instance
"demandmod" with the following references:

  X.Y = <demandmod>
  A.Y = <demandmod>
  B.Y = <demandmod>

The locals from the first consumer (A) would be stored in <demandmod1>.
When <demandmod1> was loaded, we'd look at the locals for the first
consumer and replace the symbol, if necessary. This resulted in state:

  X.Y = <module>
  A.Y = <module>
  B.Y = <demandmod>

B's reference to Y wasn't updated and was still using the proxy object
because we just didn't record that B had a reference to <demandmod> that
needed updating!

With this patch, we add support for tracking which modules in addition
to the initial importer have a reference to the _demandmod instance and
we replace those references at module load time.

In the case of posix.py, this fixes an issue where the "encoding" module
was being proxied, resulting in hundreds of thousands of
__getattribute__ lookups on the _demandmod instance during dirstate
operations on mozilla-central, speeding up execution by many
milliseconds. There are likely several other operation that benefit from
this change as well.

The new mechanism isn't perfect: references in locals (not globals) may
likely linger. So, if there is an import inside a function and a symbol
from that module is used in a hot loop, we could have unwanted overhead
from proxying through _demandmod. Non-global imports are discouraged
anyway. So hopefully this isn't a big deal in practice. We could
potentially deploy a code checker that bans use of attribute lookups of
function-level-imported modules inside loops.

This deficiency in theory could be avoided by storing the set of globals
and locals dicts to update in the _demandmod instance. However, I tried
this and it didn't work. One reason is that some globals are _demandmod
instances. We could work around this, but it's a bit more work. There
also might be other module import foo at play. The solution as
implemented is better than what we had and IMO is good enough for the
time being.

It's worth noting that this sub-optimal behavior was made worse by the
introduction of absolute_import and its recommended "from . import X"
syntax for importing modules from the "mercurial" package. If we ever
wrote performance tests, measuring the amount of module imports and
__getattribute__ proxy calls through _demandmod instances would be
something I'd have it check.

test that a commit clears the merge state.

  $ hg init repo
  $ cd repo

  $ echo foo > file1
  $ echo foo > file2
  $ hg commit -Am 'add files'
  adding file1
  adding file2

  $ echo bar >> file1
  $ echo bar >> file2
  $ hg commit -Am 'append bar to files'

create a second head with conflicting edits

  $ hg up -C 0
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo baz >> file1
  $ echo baz >> file2
  $ hg commit -Am 'append baz to files'
  created new head

create a third head with no conflicting edits
  $ hg up -qC 0
  $ echo foo > file3
  $ hg commit -Am 'add non-conflicting file'
  adding file3
  created new head

failing merge

  $ hg up -qC 2
  $ hg merge --tool=internal:fail 1
  0 files updated, 0 files merged, 0 files removed, 2 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]

resolve -l should contain unresolved entries

  $ hg resolve -l
  U file1
  U file2

  $ hg resolve -l --no-status
  file1
  file2

resolving an unknown path should emit a warning, but not for -l

  $ hg resolve -m does-not-exist
  arguments do not match paths that need resolving
  $ hg resolve -l does-not-exist

resolve the failure

  $ echo resolved > file1
  $ hg resolve -m file1

resolve -l should show resolved file as resolved

  $ hg resolve -l
  R file1
  U file2

  $ hg resolve -l -Tjson
  [
   {
    "path": "file1",
    "status": "R"
   },
   {
    "path": "file2",
    "status": "U"
   }
  ]

resolve -m without paths should mark all resolved

  $ hg resolve -m
  (no more unresolved files)
  $ hg commit -m 'resolved'

resolve -l should be empty after commit

  $ hg resolve -l

  $ hg resolve -l -Tjson
  [
  ]

resolve --all should abort when no merge in progress

  $ hg resolve --all
  abort: resolve command not applicable when not merging
  [255]

resolve -m should abort when no merge in progress

  $ hg resolve -m
  abort: resolve command not applicable when not merging
  [255]

set up conflict-free merge

  $ hg up -qC 3
  $ hg merge 1
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

resolve --all should do nothing in merge without conflicts
  $ hg resolve --all
  (no more unresolved files)

resolve -m should do nothing in merge without conflicts

  $ hg resolve -m
  (no more unresolved files)

get back to conflicting state

  $ hg up -qC 2
  $ hg merge --tool=internal:fail 1
  0 files updated, 0 files merged, 0 files removed, 2 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]

resolve without arguments should suggest --all
  $ hg resolve
  abort: no files or directories specified
  (use --all to re-merge all unresolved files)
  [255]

resolve --all should re-merge all unresolved files
  $ hg resolve -q --all
  warning: conflicts during merge.
  merging file1 incomplete! (edit conflicts, then use 'hg resolve --mark')
  warning: conflicts during merge.
  merging file2 incomplete! (edit conflicts, then use 'hg resolve --mark')
  [1]
  $ grep '<<<' file1 > /dev/null
  $ grep '<<<' file2 > /dev/null

resolve <file> should re-merge file
  $ echo resolved > file1
  $ hg resolve -q file1
  warning: conflicts during merge.
  merging file1 incomplete! (edit conflicts, then use 'hg resolve --mark')
  [1]
  $ grep '<<<' file1 > /dev/null

resolve <file> should do nothing if 'file' was marked resolved
  $ echo resolved > file1
  $ hg resolve -m file1
  $ hg resolve -q file1
  $ cat file1
  resolved

test crashed merge with empty mergestate

  $ hg up -qC 1
  $ mkdir .hg/merge
  $ touch .hg/merge/state

resolve -l should be empty

  $ hg resolve -l

  $ cd ..