view tests/test-update-reverse.t @ 44185:a19331456d48

rust-nodemap: mutable NodeTree data structure

Thanks to the previously indexing abstraction,
the only difference in the lookup algorithm is that we
don't need the special case for an empty NodeTree any more.

We've considered making the mutable root an `Option<Block>`,
but that leads to unpleasant checks and `unwrap()` unless we
abstract it as typestate patterns (`NodeTree<Immutable>` and
`NodeTree<Mutated>`) which seem exaggerated in that
case.

The initial copy of the root block is a very minor
performance penalty, given that it typically occurs just once
per transaction.

Differential Revision: https://phab.mercurial-scm.org/D7793

  $ hg init

  $ touch a
  $ hg add a
  $ hg commit -m "Added a"

  $ touch main
  $ hg add main
  $ hg commit -m "Added main"
  $ hg checkout 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

'main' should be gone:

  $ ls
  a

  $ touch side1
  $ hg add side1
  $ hg commit -m "Added side1"
  created new head
  $ touch side2
  $ hg add side2
  $ hg commit -m "Added side2"

  $ hg log
  changeset:   3:91ebc10ed028
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added side2
  
  changeset:   2:b932d7dbb1e1
  parent:      0:c2eda428b523
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added side1
  
  changeset:   1:71a760306caf
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added main
  
  changeset:   0:c2eda428b523
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added a
  

  $ hg heads
  changeset:   3:91ebc10ed028
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added side2
  
  changeset:   1:71a760306caf
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added main
  
  $ ls
  a
  side1
  side2

  $ hg update --debug -C 1
  resolving manifests
   branchmerge: False, force: True, partial: False
   ancestor: 91ebc10ed028+, local: 91ebc10ed028+, remote: 71a760306caf
   side1: other deleted -> r
  removing side1
   side2: other deleted -> r
  removing side2
   main: remote created -> g
  getting main
  1 files updated, 0 files merged, 2 files removed, 0 files unresolved

  $ ls
  a
  main