view tests/test-diff-color.t @ 36820:f33a87cf60cc

xdiff: add a preprocessing step that trims files

xdiff has a `xdl_trim_ends` step that removes common lines, unmatchable
lines. That is in theory good, but happens too late - after splitting,
hashing, and adjusting the hash values so they are unique. Those splitting,
hashing and adjusting hash values steps could have noticeable overhead.

Diffing two large files with minor (one-line-ish) changes are not uncommon.
In that case, the raw performance of those preparation steps seriously
matter. Even allocating an O(N) array and storing line offsets to it is
expensive.  Therefore my previous attempts [1] [2] cannot be good enough
since they do not remove the O(N) array assignment.

This patch adds a preprocessing step - `xdl_trim_files` that runs before
other preprocessing steps. It counts common prefix and suffix and lines in
them (needed for displaying line number), without doing anything else.

Testing with a crafted large (169MB) file, with minor change:

```
  open('a','w').write(''.join('%s\n' % (i % 100000) for i in xrange(30000000) if i != 6000000))
  open('b','w').write(''.join('%s\n' % (i % 100000) for i in xrange(30000000) if i != 6003000))
```

Running xdiff by a simple binary [3], this patch improves the xdiff perf by
more than 10x for the above case:

```
  # xdiff before this patch
  2.41s user 1.13s system 98% cpu 3.592 total
  # xdiff after this patch
  0.14s user 0.16s system 98% cpu 0.309 total
  # gnu diffutils
  0.12s user 0.15s system 98% cpu 0.272 total
  # (best of 20 runs)
```

It's still slightly slower than GNU diffutils. But it's pretty close now.

Testing with real repo data:

For the whole repo, this patch makes xdiff 25% faster:

```
  # hg perfbdiff --count 100 --alldata -c d334afc585e2 --blocks [--xdiff]
  # xdiff, after
  ! wall 0.058861 comb 0.050000 user 0.050000 sys 0.000000 (best of 100)
  # xdiff, before
  ! wall 0.077816 comb 0.080000 user 0.080000 sys 0.000000 (best of 91)
  # bdiff
  ! wall 0.117473 comb 0.120000 user 0.120000 sys 0.000000 (best of 67)
```

For files that are long (ex. commands.py), the speedup is more than 3x, very
significant:

```
  # hg perfbdiff --count 3000 --blocks commands.py.i 1 [--xdiff]
  # xdiff, after
  ! wall 0.690583 comb 0.690000 user 0.690000 sys 0.000000 (best of 12)
  # xdiff, before
  ! wall 2.240361 comb 2.210000 user 2.210000 sys 0.000000 (best of 4)
  # bdiff
  ! wall 2.469852 comb 2.440000 user 2.440000 sys 0.000000 (best of 4)
```

[1]: https://phab.mercurial-scm.org/D2631
[2]: https://phab.mercurial-scm.org/D2634
[3]:

```
// Code to run xdiff from command line. No proper error handling.
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "mercurial/thirdparty/xdiff/xdiff.h"
#define ensure(x) if (!(x)) exit(255);
mmfile_t readfile(const char *path) {
  struct stat st; int fd = open(path, O_RDONLY);
  fstat(fd, &st); mmfile_t file = { malloc(st.st_size), st.st_size };
  ensure(read(fd, file.ptr, st.st_size) == st.st_size); close(fd);
  return file;
}
int main(int argc, char const *argv[]) {
  mmfile_t a = readfile(argv[1]), b = readfile(argv[2]);
  xpparam_t xpp = {0}; xdemitconf_t xecfg = {0}; xdemitcb_t ecb = {0};
  xdl_diff(&a, &b, &xpp, &xecfg, &ecb);
  return 0;
}
```

Differential Revision: https://phab.mercurial-scm.org/D2686

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 ..

test inline color diff

  $ hg init inline
  $ cd inline
  $ cat > file1 << EOF
  > this is the first line
  > this is the second line
  >     third line starts with space
  > + starts with a plus sign
  > 	this one with one tab
  > 		now with full two tabs
  > 	now tabs		everywhere, much fun
  > 
  > this line won't change
  > 
  > two lines are going to
  > be changed into three!
  > 
  > three of those lines will
  > collapse onto one
  > (to see if it works)
  > EOF
  $ hg add file1
  $ hg ci -m 'commit'

  $ cat > file1 << EOF
  > that is the first paragraph
  >     this is the second line
  > third line starts with space
  > - starts with a minus sign
  > 	this one with two tab
  > 			now with full three tabs
  > 	now there are tabs		everywhere, much fun
  > 
  > this line won't change
  > 
  > two lines are going to
  > (entirely magically,
  >  assuming this works)
  > be changed into four!
  > 
  > three of those lines have
  > collapsed onto one
  > EOF
  $ hg diff --config experimental.worddiff=False --color=debug
  [diff.diffline|diff --git a/file1 b/file1]
  [diff.file_a|--- a/file1]
  [diff.file_b|+++ b/file1]
  [diff.hunk|@@ -1,16 +1,17 @@]
  [diff.deleted|-this is the first line]
  [diff.deleted|-this is the second line]
  [diff.deleted|-    third line starts with space]
  [diff.deleted|-+ starts with a plus sign]
  [diff.deleted|-][diff.tab|	][diff.deleted|this one with one tab]
  [diff.deleted|-][diff.tab|		][diff.deleted|now with full two tabs]
  [diff.deleted|-][diff.tab|	][diff.deleted|now tabs][diff.tab|		][diff.deleted|everywhere, much fun]
  [diff.inserted|+that is the first paragraph]
  [diff.inserted|+    this is the second line]
  [diff.inserted|+third line starts with space]
  [diff.inserted|+- starts with a minus sign]
  [diff.inserted|+][diff.tab|	][diff.inserted|this one with two tab]
  [diff.inserted|+][diff.tab|			][diff.inserted|now with full three tabs]
  [diff.inserted|+][diff.tab|	][diff.inserted|now there are tabs][diff.tab|		][diff.inserted|everywhere, much fun]
   
   this line won't change
   
   two lines are going to
  [diff.deleted|-be changed into three!]
  [diff.inserted|+(entirely magically,]
  [diff.inserted|+ assuming this works)]
  [diff.inserted|+be changed into four!]
   
  [diff.deleted|-three of those lines will]
  [diff.deleted|-collapse onto one]
  [diff.deleted|-(to see if it works)]
  [diff.inserted|+three of those lines have]
  [diff.inserted|+collapsed onto one]
  $ hg diff --config experimental.worddiff=True --color=debug
  [diff.diffline|diff --git a/file1 b/file1]
  [diff.file_a|--- a/file1]
  [diff.file_b|+++ b/file1]
  [diff.hunk|@@ -1,16 +1,17 @@]
  [diff.deleted|-this is the ][diff.deleted.highlight|first][diff.deleted| line]
  [diff.deleted|-this is the second line]
  [diff.deleted|-][diff.deleted.highlight|    ][diff.deleted|third line starts with space]
  [diff.deleted|-][diff.deleted.highlight|+][diff.deleted| starts with a ][diff.deleted.highlight|plus][diff.deleted| sign]
  [diff.deleted|-][diff.tab|	][diff.deleted|this one with ][diff.deleted.highlight|one][diff.deleted| tab]
  [diff.deleted|-][diff.tab|		][diff.deleted|now with full ][diff.deleted.highlight|two][diff.deleted| tabs]
  [diff.deleted|-][diff.tab|	][diff.deleted|now tabs][diff.tab|		][diff.deleted|everywhere, much fun]
  [diff.inserted|+that is the first paragraph]
  [diff.inserted|+][diff.inserted.highlight|    ][diff.inserted|this is the ][diff.inserted.highlight|second][diff.inserted| line]
  [diff.inserted|+third line starts with space]
  [diff.inserted|+][diff.inserted.highlight|-][diff.inserted| starts with a ][diff.inserted.highlight|minus][diff.inserted| sign]
  [diff.inserted|+][diff.tab|	][diff.inserted|this one with ][diff.inserted.highlight|two][diff.inserted| tab]
  [diff.inserted|+][diff.tab|			][diff.inserted|now with full ][diff.inserted.highlight|three][diff.inserted| tabs]
  [diff.inserted|+][diff.tab|	][diff.inserted|now][diff.inserted.highlight| there are][diff.inserted| tabs][diff.tab|		][diff.inserted|everywhere, much fun]
   
   this line won't change
   
   two lines are going to
  [diff.deleted|-be changed into ][diff.deleted.highlight|three][diff.deleted|!]
  [diff.inserted|+(entirely magically,]
  [diff.inserted|+ assuming this works)]
  [diff.inserted|+be changed into ][diff.inserted.highlight|four][diff.inserted|!]
   
  [diff.deleted|-three of those lines ][diff.deleted.highlight|will]
  [diff.deleted|-][diff.deleted.highlight|collapse][diff.deleted| onto one]
  [diff.deleted|-(to see if it works)]
  [diff.inserted|+three of those lines ][diff.inserted.highlight|have]
  [diff.inserted|+][diff.inserted.highlight|collapsed][diff.inserted| onto one]

multibyte character shouldn't be broken up in word diff:

  $ $PYTHON <<'EOF'
  > with open("utf8", "wb") as f:
  >     f.write(b"blah \xe3\x82\xa2 blah\n")
  > EOF
  $ hg ci -Am 'add utf8 char' utf8
  $ $PYTHON <<'EOF'
  > with open("utf8", "wb") as f:
  >     f.write(b"blah \xe3\x82\xa4 blah\n")
  > EOF
  $ hg ci -m 'slightly change utf8 char' utf8
  $ hg diff --config experimental.worddiff=True --color=debug -c.
  [diff.diffline|diff --git a/utf8 b/utf8]
  [diff.file_a|--- a/utf8]
  [diff.file_b|+++ b/utf8]
  [diff.hunk|@@ -1,1 +1,1 @@]
  [diff.deleted|-blah ][diff.deleted.highlight|\xe3\x82\xa2][diff.deleted| blah] (esc)
  [diff.inserted|+blah ][diff.inserted.highlight|\xe3\x82\xa4][diff.inserted| blah] (esc)