view tests/test-diff-color.t @ 33207:895ecec31c70

revlog: add an experimental option to mitigated delta issues (issue5480)

The general delta heuristic to select a delta do not scale with the number of
branch. The delta base is frequently too far away to be able to reuse a chain
according to the "distance" criteria. This leads to insertion of larger delta (or
even full text) that themselves push the bases for the next delta further away
leading to more large deltas and full texts. This full text and frequent
recomputation throw Mercurial performance in disarray.

For example of a slightly large repository

  280 000 files (2 150 000 versions)
  430 000 changesets (10 000 topological heads)

Number below compares repository with and without the distance criteria:

manifest size:
    with:    21.4 GB
    without:  0.3 GB

store size:
    with:    28.7 GB
    without   7.4 GB

bundle last 15 00 revisions:
    with:    800 seconds
             971 MB
    without:  50 seconds
              73 MB

unbundle time (of the last 15K revisions):
    with:    1150 seconds (~19 minutes)
    without:   35 seconds

Similar issues has been observed in other repositories.


Adding a new option or "feature" on stable is uncommon. However, given that this
issues is making Mercurial practically unusable, I'm exceptionally targeting
this patch for stable.

What is actually needed is a full rework of the delta building and reading
logic. However, that will be a longer process and churn not suitable for stable.

In the meantime, we introduces a quick and dirty mitigation of this in the
'experimental' config space. The new option introduces a way to set the maximum
amount of memory usable to store a diff in memory. This extend the ability for
Mercurial to create chains without removing all safe guard regarding memory
access. The option should be phased out when core has a more proper solution
available.

Setting the limit to '0' remove all limits, setting it to '-1' use the default
limit (textsize x 4).

Setup

  $ cat <<EOF >> $HGRCPATH
  > [ui]
  > color = yes
  > formatted = always
  > paginate = never
  > [color]
  > mode = ansi
  > EOF
  $ hg init repo
  $ cd repo
  $ cat > a <<EOF
  > c
  > c
  > a
  > a
  > b
  > a
  > a
  > c
  > c
  > EOF
  $ hg ci -Am adda
  adding a
  $ cat > a <<EOF
  > c
  > c
  > a
  > a
  > dd
  > a
  > a
  > c
  > c
  > EOF

default context

  $ hg diff --nodates
  \x1b[0;1mdiff -r cf9f4ba66af2 a\x1b[0m (esc)
  \x1b[0;31;1m--- a/a\x1b[0m (esc)
  \x1b[0;32;1m+++ b/a\x1b[0m (esc)
  \x1b[0;35m@@ -2,7 +2,7 @@\x1b[0m (esc)
   c
   a
   a
  \x1b[0;31m-b\x1b[0m (esc)
  \x1b[0;32m+dd\x1b[0m (esc)
   a
   a
   c

(check that 'ui.color=yes' match '--color=auto')

  $ hg diff --nodates --config ui.formatted=no
  diff -r cf9f4ba66af2 a
  --- a/a
  +++ b/a
  @@ -2,7 +2,7 @@
   c
   a
   a
  -b
  +dd
   a
   a
   c

(check that 'ui.color=no' disable color)

  $ hg diff --nodates --config ui.formatted=yes --config ui.color=no
  diff -r cf9f4ba66af2 a
  --- a/a
  +++ b/a
  @@ -2,7 +2,7 @@
   c
   a
   a
  -b
  +dd
   a
   a
   c

(check that 'ui.color=always' force color)

  $ hg diff --nodates --config ui.formatted=no --config ui.color=always
  \x1b[0;1mdiff -r cf9f4ba66af2 a\x1b[0m (esc)
  \x1b[0;31;1m--- a/a\x1b[0m (esc)
  \x1b[0;32;1m+++ b/a\x1b[0m (esc)
  \x1b[0;35m@@ -2,7 +2,7 @@\x1b[0m (esc)
   c
   a
   a
  \x1b[0;31m-b\x1b[0m (esc)
  \x1b[0;32m+dd\x1b[0m (esc)
   a
   a
   c

--unified=2

  $ hg diff --nodates -U 2
  \x1b[0;1mdiff -r cf9f4ba66af2 a\x1b[0m (esc)
  \x1b[0;31;1m--- a/a\x1b[0m (esc)
  \x1b[0;32;1m+++ b/a\x1b[0m (esc)
  \x1b[0;35m@@ -3,5 +3,5 @@\x1b[0m (esc)
   a
   a
  \x1b[0;31m-b\x1b[0m (esc)
  \x1b[0;32m+dd\x1b[0m (esc)
   a
   a

diffstat

  $ hg diff --stat
   a |  2 \x1b[0;32m+\x1b[0m\x1b[0;31m-\x1b[0m (esc)
   1 files changed, 1 insertions(+), 1 deletions(-)
  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > record =
  > [ui]
  > interactive = true
  > [diff]
  > git = True
  > EOF

#if execbit

record

  $ chmod +x a
  $ hg record -m moda a <<EOF
  > y
  > y
  > EOF
  \x1b[0;1mdiff --git a/a b/a\x1b[0m (esc)
  \x1b[0;36;1mold mode 100644\x1b[0m (esc)
  \x1b[0;36;1mnew mode 100755\x1b[0m (esc)
  1 hunks, 1 lines changed
  \x1b[0;33mexamine changes to 'a'? [Ynesfdaq?]\x1b[0m y (esc)
  
  \x1b[0;35m@@ -2,7 +2,7 @@ c\x1b[0m (esc)
   c
   a
   a
  \x1b[0;31m-b\x1b[0m (esc)
  \x1b[0;32m+dd\x1b[0m (esc)
   a
   a
   c
  \x1b[0;33mrecord this change to 'a'? [Ynesfdaq?]\x1b[0m y (esc)
  

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH
  $ hg rollback
  repository tip rolled back to revision 0 (undo commit)
  working directory now based on revision 0

qrecord

  $ hg qrecord -m moda patch <<EOF
  > y
  > y
  > EOF
  \x1b[0;1mdiff --git a/a b/a\x1b[0m (esc)
  \x1b[0;36;1mold mode 100644\x1b[0m (esc)
  \x1b[0;36;1mnew mode 100755\x1b[0m (esc)
  1 hunks, 1 lines changed
  \x1b[0;33mexamine changes to 'a'? [Ynesfdaq?]\x1b[0m y (esc)
  
  \x1b[0;35m@@ -2,7 +2,7 @@ c\x1b[0m (esc)
   c
   a
   a
  \x1b[0;31m-b\x1b[0m (esc)
  \x1b[0;32m+dd\x1b[0m (esc)
   a
   a
   c
  \x1b[0;33mrecord this change to 'a'? [Ynesfdaq?]\x1b[0m y (esc)
  

  $ hg qpop -a
  popping patch
  patch queue now empty

#endif

issue3712: test colorization of subrepo diff

  $ hg init sub
  $ echo b > sub/b
  $ hg -R sub commit -Am 'create sub'
  adding b
  $ echo 'sub = sub' > .hgsub
  $ hg add .hgsub
  $ hg commit -m 'add subrepo sub'
  $ echo aa >> a
  $ echo bb >> sub/b

  $ hg diff -S
  \x1b[0;1mdiff --git a/a b/a\x1b[0m (esc)
  \x1b[0;31;1m--- a/a\x1b[0m (esc)
  \x1b[0;32;1m+++ b/a\x1b[0m (esc)
  \x1b[0;35m@@ -7,3 +7,4 @@\x1b[0m (esc)
   a
   c
   c
  \x1b[0;32m+aa\x1b[0m (esc)
  \x1b[0;1mdiff --git a/sub/b b/sub/b\x1b[0m (esc)
  \x1b[0;31;1m--- a/sub/b\x1b[0m (esc)
  \x1b[0;32;1m+++ b/sub/b\x1b[0m (esc)
  \x1b[0;35m@@ -1,1 +1,2 @@\x1b[0m (esc)
   b
  \x1b[0;32m+bb\x1b[0m (esc)

test tabs

  $ cat >> a <<EOF
  > 	one tab
  > 		two tabs
  > end tab	
  > mid	tab
  > 	all		tabs	
  > EOF
  $ hg diff --nodates
  \x1b[0;1mdiff --git a/a b/a\x1b[0m (esc)
  \x1b[0;31;1m--- a/a\x1b[0m (esc)
  \x1b[0;32;1m+++ b/a\x1b[0m (esc)
  \x1b[0;35m@@ -7,3 +7,9 @@\x1b[0m (esc)
   a
   c
   c
  \x1b[0;32m+aa\x1b[0m (esc)
  \x1b[0;32m+\x1b[0m	\x1b[0;32mone tab\x1b[0m (esc)
  \x1b[0;32m+\x1b[0m		\x1b[0;32mtwo tabs\x1b[0m (esc)
  \x1b[0;32m+end tab\x1b[0m\x1b[0;1;41m	\x1b[0m (esc)
  \x1b[0;32m+mid\x1b[0m	\x1b[0;32mtab\x1b[0m (esc)
  \x1b[0;32m+\x1b[0m	\x1b[0;32mall\x1b[0m		\x1b[0;32mtabs\x1b[0m\x1b[0;1;41m	\x1b[0m (esc)
  $ echo "[color]" >> $HGRCPATH
  $ echo "diff.tab = bold magenta" >> $HGRCPATH
  $ hg diff --nodates
  \x1b[0;1mdiff --git a/a b/a\x1b[0m (esc)
  \x1b[0;31;1m--- a/a\x1b[0m (esc)
  \x1b[0;32;1m+++ b/a\x1b[0m (esc)
  \x1b[0;35m@@ -7,3 +7,9 @@\x1b[0m (esc)
   a
   c
   c
  \x1b[0;32m+aa\x1b[0m (esc)
  \x1b[0;32m+\x1b[0m\x1b[0;1;35m	\x1b[0m\x1b[0;32mone tab\x1b[0m (esc)
  \x1b[0;32m+\x1b[0m\x1b[0;1;35m		\x1b[0m\x1b[0;32mtwo tabs\x1b[0m (esc)
  \x1b[0;32m+end tab\x1b[0m\x1b[0;1;41m	\x1b[0m (esc)
  \x1b[0;32m+mid\x1b[0m\x1b[0;1;35m	\x1b[0m\x1b[0;32mtab\x1b[0m (esc)
  \x1b[0;32m+\x1b[0m\x1b[0;1;35m	\x1b[0m\x1b[0;32mall\x1b[0m\x1b[0;1;35m		\x1b[0m\x1b[0;32mtabs\x1b[0m\x1b[0;1;41m	\x1b[0m (esc)

  $ cd ..