view tests/test-diff-color.t @ 40021:c537144fdbef

wireprotov2: support response caching

One of the things I've learned from managing VCS servers over the
years is that they are hard to scale. It is well known that some
companies have very beefy (read: very expensive) servers to power
their VCS needs. It is also known that specialized servers for
various VCS exist in order to facilitate scaling servers. (Mercurial
is in this boat.)

One of the aspects that make a VCS server hard to scale is the
high CPU load incurred by constant client clone/pull operations.

To alleviate the scaling pain associated with data retrieval
operations, I want to integrate caching into the Mercurial wire
protocol server as robustly as possible such that servers can
aggressively cache responses and defer as much server load as
possible.

This commit represents the initial implementation of a general
caching layer in wire protocol version 2.

We define a new interface and behavior for a wire protocol cacher
in repository.py. (This is probably where a reviewer should look
first to understand what is going on.)

The bulk of the added code is in wireprotov2server.py, where we
define how a command can opt in to being cached and integrate
caching into command dispatching.

From a very high-level:

* A command can declare itself as cacheable by providing a callable
  that can be used to derive a cache key.
* At dispatch time, if a command is cacheable, we attempt to
  construct a cacher and use it for serving the request and/or
  caching the request.
* The dispatch layer handles the bulk of the business logic for
  caching, making cachers mostly "dumb content stores."
* The mechanism for invalidating cached entries (one of the harder
  parts about caching in general) is by varying the cache key when
  state changes. As such, cachers don't need to be concerned with
  cache invalidation.

Initially, we've hooked up support for caching "manifestdata" and
"filedata" commands. These are the simplest to cache, as they should
be immutable over time. Caching of commands related to changeset
data is a bit harder (because cache validation is impacted by
changes to bookmarks, phases, etc). This will be implemented later.
(Strictly speaking, censoring a file should invalidate caches. I've
added an inline TODO to track this edge case.)

To prove it works, this commit implements a test-only extension
providing in-memory caching backed by an lrucachedict. A new test
showing this extension behaving properly is added. FWIW, the
cacher is ~50 lines of code, demonstrating the relative ease with
which a cache can be added to a server.

While the test cacher is not suitable for production workloads, just
for kicks I performed a clone of just the changeset and manifest data
for the mozilla-unified repository. With a fully warmed cache (of just
the manifest data since changeset data is not cached), server-side
CPU usage dropped from ~73s to ~28s. That's pretty significant and
demonstrates the potential that response caching has on server
scalability!

Differential Revision: https://phab.mercurial-scm.org/D4773

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
  \x1b[0;32madding a\x1b[0m (esc)
  $ 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

trailing whitespace

  $ cp a a.orig
  >>> with open('a', 'rb') as f:
  ...     data = f.read()
  >>> with open('a', 'wb') as f:
  ...     f.write(data.replace(b'dd', b'dd \r')) and None
  $ 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\x1b[0;1;41m \x1b[0m\r (esc)
   a
   a
   c

  $ mv a.orig a

(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'
  \x1b[0;32madding b\x1b[0m (esc)
  $ 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 diff.word-diff=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 diff.word-diff=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|-][diff.deleted.changed|this][diff.deleted.unchanged| is the first ][diff.deleted.changed|line]
  [diff.deleted|-][diff.deleted.unchanged|this is the second line]
  [diff.deleted|-][diff.deleted.changed|    ][diff.deleted.unchanged|third line starts with space]
  [diff.deleted|-][diff.deleted.changed|+][diff.deleted.unchanged| starts with a ][diff.deleted.changed|plus][diff.deleted.unchanged| sign]
  [diff.deleted|-][diff.tab|	][diff.deleted.unchanged|this one with ][diff.deleted.changed|one][diff.deleted.unchanged| tab]
  [diff.deleted|-][diff.tab|		][diff.deleted.unchanged|now with full ][diff.deleted.changed|two][diff.deleted.unchanged| tabs]
  [diff.deleted|-][diff.tab|	][diff.deleted.unchanged|now ][diff.deleted.unchanged|tabs][diff.tab|		][diff.deleted.unchanged|everywhere, much fun]
  [diff.inserted|+][diff.inserted.changed|that][diff.inserted.unchanged| is the first ][diff.inserted.changed|paragraph]
  [diff.inserted|+][diff.inserted.changed|    ][diff.inserted.unchanged|this is the second line]
  [diff.inserted|+][diff.inserted.unchanged|third line starts with space]
  [diff.inserted|+][diff.inserted.changed|-][diff.inserted.unchanged| starts with a ][diff.inserted.changed|minus][diff.inserted.unchanged| sign]
  [diff.inserted|+][diff.tab|	][diff.inserted.unchanged|this one with ][diff.inserted.changed|two][diff.inserted.unchanged| tab]
  [diff.inserted|+][diff.tab|			][diff.inserted.unchanged|now with full ][diff.inserted.changed|three][diff.inserted.unchanged| tabs]
  [diff.inserted|+][diff.tab|	][diff.inserted.unchanged|now ][diff.inserted.changed|there are ][diff.inserted.unchanged|tabs][diff.tab|		][diff.inserted.unchanged|everywhere, much fun]
   
   this line won't change
   
   two lines are going to
  [diff.deleted|-][diff.deleted.unchanged|be changed into ][diff.deleted.changed|three][diff.deleted.unchanged|!]
  [diff.inserted|+][diff.inserted.changed|(entirely magically,]
  [diff.inserted|+][diff.inserted.changed| assuming this works)]
  [diff.inserted|+][diff.inserted.unchanged|be changed into ][diff.inserted.changed|four][diff.inserted.unchanged|!]
   
  [diff.deleted|-][diff.deleted.unchanged|three of those lines ][diff.deleted.changed|will]
  [diff.deleted|-][diff.deleted.changed|collapse][diff.deleted.unchanged| onto one]
  [diff.deleted|-][diff.deleted.changed|(to see if it works)]
  [diff.inserted|+][diff.inserted.unchanged|three of those lines ][diff.inserted.changed|have]
  [diff.inserted|+][diff.inserted.changed|collapsed][diff.inserted.unchanged| 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 diff.word-diff=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|-][diff.deleted.unchanged|blah ][diff.deleted.changed|\xe3\x82\xa2][diff.deleted.unchanged| blah] (esc)
  [diff.inserted|+][diff.inserted.unchanged|blah ][diff.inserted.changed|\xe3\x82\xa4][diff.inserted.unchanged| blah] (esc)