view tests/test-diff-ignore-whitespace.t @ 30212:260af19891f2

changegroup: increase write buffer size to 128k

By default, Python defers to the operating system for choosing the
default buffer size on opened files. On my Linux machine, the default
is 4k, which is really small for 2016.

This patch bumps the write buffer size when writing
changegroups/bundles to 128k. This matches the 128k read buffer
we already use on revlogs.

It's worth noting that this only impacts when writing to an explicit
file (such as during `hg bundle`). Buffers when writing to bundle
files via the repo vfs or to a temporary file are not impacted.

When producing a none-v2 bundle file of the mozilla-unified repository,
this change caused the number of write() system calls to drop from
952,449 to 29,788. After this change, the most frequent system
calls are fstat(), read(), lseek(), and open(). There were
2,523,672 system calls after this patch (so a net decrease of
~950k is statistically significant).

This change shows no performance change on my system. But I have a
high-end system with a fast SSD. It is quite possible this change
will have a significant impact on network file systems, where
extra network round trips due to excessive I/O system calls could
introduce significant latency.

GNU diff is the reference for all of these results.

Prepare tests:

  $ echo '[alias]' >> $HGRCPATH
  $ echo 'ndiff = diff --nodates' >> $HGRCPATH

  $ hg init
  $ printf 'hello world\ngoodbye world\n' >foo
  $ hg ci -Amfoo -ufoo
  adding foo


Test added blank lines:

  $ printf '\nhello world\n\ngoodbye world\n\n' >foo

>>> two diffs showing three added lines <<<

  $ hg ndiff
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,5 @@
  +
   hello world
  +
   goodbye world
  +
  $ hg ndiff -b
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,5 @@
  +
   hello world
  +
   goodbye world
  +

>>> no diffs <<<

  $ hg ndiff -B
  $ hg ndiff -Bb


Test added horizontal space first on a line():

  $ printf '\t hello world\ngoodbye world\n' >foo

>>> four diffs showing added space first on the first line <<<

  $ hg ndiff
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
  -hello world
  +	 hello world
   goodbye world

  $ hg ndiff -b
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
  -hello world
  +	 hello world
   goodbye world

  $ hg ndiff -B
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
  -hello world
  +	 hello world
   goodbye world

  $ hg ndiff -Bb
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
  -hello world
  +	 hello world
   goodbye world


Test added horizontal space last on a line:

  $ printf 'hello world\t \ngoodbye world\n' >foo

>>> two diffs showing space appended to the first line <<<

  $ hg ndiff
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
  -hello world
  +hello world	 
   goodbye world

  $ hg ndiff -B
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
  -hello world
  +hello world	 
   goodbye world

>>> no diffs <<<

  $ hg ndiff -b
  $ hg ndiff -Bb


Test added horizontal space in the middle of a word:

  $ printf 'hello world\ngood bye world\n' >foo

>>> four diffs showing space inserted into "goodbye" <<<

  $ hg ndiff
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
   hello world
  -goodbye world
  +good bye world

  $ hg ndiff -B
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
   hello world
  -goodbye world
  +good bye world

  $ hg ndiff -b
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
   hello world
  -goodbye world
  +good bye world

  $ hg ndiff -Bb
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
   hello world
  -goodbye world
  +good bye world


Test increased horizontal whitespace amount:

  $ printf 'hello world\ngoodbye\t\t  \tworld\n' >foo

>>> two diffs showing changed whitespace amount in the last line <<<

  $ hg ndiff
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
   hello world
  -goodbye world
  +goodbye		  	world

  $ hg ndiff -B
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
   hello world
  -goodbye world
  +goodbye		  	world

>>> no diffs <<<

  $ hg ndiff -b
  $ hg ndiff -Bb


Test added blank line with horizontal whitespace:

  $ printf 'hello world\n \t\ngoodbye world\n' >foo

>>> three diffs showing added blank line with horizontal space <<<

  $ hg ndiff
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,3 @@
   hello world
  + 	
   goodbye world

  $ hg ndiff -B
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,3 @@
   hello world
  + 	
   goodbye world

  $ hg ndiff -b
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,3 @@
   hello world
  + 	
   goodbye world

>>> no diffs <<<

  $ hg ndiff -Bb


Test added blank line with other whitespace:

  $ printf 'hello  world\n \t\ngoodbye world \n' >foo

>>> three diffs showing added blank line with other space <<<

  $ hg ndiff
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,3 @@
  -hello world
  -goodbye world
  +hello  world
  + 	
  +goodbye world 

  $ hg ndiff -B
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,3 @@
  -hello world
  -goodbye world
  +hello  world
  + 	
  +goodbye world 

  $ hg ndiff -b
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,3 @@
   hello world
  + 	
   goodbye world

>>> no diffs <<<

  $ hg ndiff -Bb


Test whitespace changes:

  $ printf 'helloworld\ngoodbye\tworld \n' >foo

>>> four diffs showing changed whitespace <<<

  $ hg ndiff
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
  -hello world
  -goodbye world
  +helloworld
  +goodbye	world 

  $ hg ndiff -B
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
  -hello world
  -goodbye world
  +helloworld
  +goodbye	world 

  $ hg ndiff -b
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
  -hello world
  +helloworld
   goodbye world

  $ hg ndiff -Bb
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,2 @@
  -hello world
  +helloworld
   goodbye world

>>> no diffs <<<

  $ hg ndiff -w


Test whitespace changes and blank lines:

  $ printf 'helloworld\n\n\n\ngoodbye\tworld \n' >foo

>>> five diffs showing changed whitespace <<<

  $ hg ndiff
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,5 @@
  -hello world
  -goodbye world
  +helloworld
  +
  +
  +
  +goodbye	world 

  $ hg ndiff -B
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,5 @@
  -hello world
  -goodbye world
  +helloworld
  +
  +
  +
  +goodbye	world 

  $ hg ndiff -b
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,5 @@
  -hello world
  +helloworld
  +
  +
  +
   goodbye world

  $ hg ndiff -Bb
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,5 @@
  -hello world
  +helloworld
  +
  +
  +
   goodbye world

  $ hg ndiff -w
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,5 @@
   hello world
  +
  +
  +
   goodbye world

>>> no diffs <<<

  $ hg ndiff -wB


Test \r (carriage return) as used in "DOS" line endings:

  $ printf 'hello world\r\n\r\ngoodbye\rworld\n' >foo

  $ hg ndiff
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,3 @@
  -hello world
  -goodbye world
  +hello world\r (esc)
  +\r (esc)
  +goodbye\r (no-eol) (esc)
  world

No completely blank lines to ignore:

  $ hg ndiff --ignore-blank-lines
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,3 @@
  -hello world
  -goodbye world
  +hello world\r (esc)
  +\r (esc)
  +goodbye\r (no-eol) (esc)
  world

Only new line noticed:

  $ hg ndiff --ignore-space-change
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,3 @@
   hello world
  +\r (esc)
   goodbye world

  $ hg ndiff --ignore-all-space
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,3 @@
   hello world
  +\r (esc)
   goodbye world

New line not noticed when space change ignored:

  $ hg ndiff --ignore-blank-lines --ignore-all-space

Do not ignore all newlines, only blank lines

  $ printf 'hello \nworld\ngoodbye world\n' > foo
  $ hg ndiff --ignore-blank-lines
  diff -r 540c40a65b78 foo
  --- a/foo
  +++ b/foo
  @@ -1,2 +1,3 @@
  -hello world
  +hello 
  +world
   goodbye world

Test hunk offsets adjustments with --ignore-blank-lines

  $ hg revert -aC
  reverting foo
  $ printf '\nb\nx\nd\n' > a
  $ printf 'b\ny\nd\n' > b
  $ hg add a b
  $ hg ci -m add
  $ hg cat -r . a > b
  $ hg cat -r . b > a
  $ hg diff -B --nodates a > ../diffa
  $ cat ../diffa
  diff -r 0e66aa54f318 a
  --- a/a
  +++ b/a
  @@ -1,4 +1,4 @@
   
   b
  -x
  +y
   d
  $ hg diff -B --nodates b > ../diffb
  $ cat ../diffb
  diff -r 0e66aa54f318 b
  --- a/b
  +++ b/b
  @@ -1,3 +1,3 @@
   b
  -y
  +x
   d
  $ hg revert -aC
  reverting a
  reverting b
  $ hg import --no-commit ../diffa
  applying ../diffa
  $ hg revert -aC
  reverting a
  $ hg import --no-commit ../diffb
  applying ../diffb
  $ hg revert -aC
  reverting b