changegroup: compute seen files as changesets are added (
issue4750)
Before this patch, addchangegroup() would walk the changelog and compute
the set of seen files between applying changesets and applying
manifests. When cloning large repositories such as mozilla-central,
this consumed a non-trivial amount of time. On my MBP, this walk takes
~10s. On a dainty EC2 instance, this was measured to take ~125s! On the
latter machine, this delay was enough for the Mercurial server to
disconnect the client, thinking it had timed out, thus causing a clone
to abort.
This patch enables the changelog to compute the set of changed files as
new revisions are added. By doing so, we:
* avoid a potentially heavy computation between changelog and manifest
processing by spreading the computation across all changelog additions
* avoid extra reads from the changelog by operating on the data as it is
added
The downside of this is that the add revision callback does result in
extra I/O. Before, we would perform a flush (and subsequent read to
construct the full revision) when new delta chains were created. For
changelogs, this is typically every 2-4 revisions. Using the callback
guarantees there will be a flush after every added revision *and* an
open + read of the changelog to obtain the full revision in order to
read the added files. So, this increases the frequency of these
operations by the average chain length. In the future, the revlog
should be smart enough to know how to read revisions that haven't been
flushed yet, thus eliminating this extra I/O.
On my MBP, the total CPU times for an `hg unbundle` with a local
mozilla-central gzip bundle containing 251,934 changesets and 211,065
files did not have a statistically significant change with this patch,
holding steady around 360s. So, the increased revlog flushing did not
have an effect.
With this patch, there is no longer a visible pause between applying
changeset and manifest data. Before, it sure felt like Mercurial was
lethargic making this transition. Now, the transition is nearly
instantaneous, giving the impression that Mercurial is faster. Of course,
eliminating this pause means that the potential for network disconnect due
to channel inactivity during the changelog walk is eliminated as well.
And that is the impetus behind this change.
== paragraphs ==
60 column format:
----------------------------------------------------------------------
This is some text in the first paragraph.
A small indented paragraph. It is followed by some lines
containing random whitespace.
The third and final paragraph.
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
This is some text in the first
paragraph.
A small indented paragraph.
It is followed by some lines
containing random
whitespace.
The third and final paragraph.
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<p>
This is some text in the first paragraph.
</p>
<p>
A small indented paragraph.
It is followed by some lines
containing random whitespace.
</p>
<p>
The third and final paragraph.
</p>
----------------------------------------------------------------------
== definitions ==
60 column format:
----------------------------------------------------------------------
A Term
Definition. The indented lines make up the definition.
Another Term
Another definition. The final line in the definition
determines the indentation, so this will be indented
with four spaces.
A Nested/Indented Term
Definition.
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
A Term
Definition. The indented
lines make up the
definition.
Another Term
Another definition. The
final line in the
definition determines the
indentation, so this will
be indented with four
spaces.
A Nested/Indented Term
Definition.
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<dl>
<dt>A Term
<dd>Definition. The indented lines make up the definition.
<dt>Another Term
<dd>Another definition. The final line in the definition determines the indentation, so this will be indented with four spaces.
<dt>A Nested/Indented Term
<dd>Definition.
</dl>
----------------------------------------------------------------------
== literals ==
60 column format:
----------------------------------------------------------------------
The fully minimized form is the most convenient form:
Hello
literal
world
In the partially minimized form a paragraph simply ends with
space-double-colon.
////////////////////////////////////////
long un-wrapped line in a literal block
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
This literal block is started with '::',
the so-called expanded form. The paragraph
with '::' disappears in the final output.
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
The fully minimized form is
the most convenient form:
Hello
literal
world
In the partially minimized
form a paragraph simply ends
with space-double-colon.
////////////////////////////////////////
long un-wrapped line in a literal block
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
This literal block is started with '::',
the so-called expanded form. The paragraph
with '::' disappears in the final output.
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<p>
The fully minimized form is the most
convenient form:
</p>
<pre>
Hello
literal
world
</pre>
<p>
In the partially minimized form a paragraph
simply ends with space-double-colon.
</p>
<pre>
////////////////////////////////////////
long un-wrapped line in a literal block
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
</pre>
<pre>
This literal block is started with '::',
the so-called expanded form. The paragraph
with '::' disappears in the final output.
</pre>
----------------------------------------------------------------------
== lists ==
60 column format:
----------------------------------------------------------------------
- This is the first list item.
Second paragraph in the first list item.
- List items need not be separated by a blank line.
- And will be rendered without one in any case.
We can have indented lists:
- This is an indented list item
- Another indented list item:
- A literal block in the middle
of an indented list.
(The above is not a list item since we are in the literal block.)
Literal block with no indentation (apart from
the two spaces added to all literal blocks).
1. This is an enumerated list (first item).
2. Continuing with the second item.
(1) foo
(2) bar
1) Another
2) List
Line blocks are also a form of list:
This is the first line. The line continues here.
This is the second line.
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
- This is the first list item.
Second paragraph in the
first list item.
- List items need not be
separated by a blank line.
- And will be rendered without
one in any case.
We can have indented lists:
- This is an indented list
item
- Another indented list
item:
- A literal block in the middle
of an indented list.
(The above is not a list item since we are in the literal block.)
Literal block with no indentation (apart from
the two spaces added to all literal blocks).
1. This is an enumerated list
(first item).
2. Continuing with the second
item.
(1) foo
(2) bar
1) Another
2) List
Line blocks are also a form of
list:
This is the first line. The
line continues here.
This is the second line.
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<ul>
<li> This is the first list item.
<p>
Second paragraph in the first list item.
</p>
<li> List items need not be separated by a blank line.
<li> And will be rendered without one in any case.
</ul>
<p>
We can have indented lists:
</p>
<ul>
<li> This is an indented list item
<li> Another indented list item:
<pre>
- A literal block in the middle
of an indented list.
</pre>
<pre>
(The above is not a list item since we are in the literal block.)
</pre>
</ul>
<pre>
Literal block with no indentation (apart from
the two spaces added to all literal blocks).
</pre>
<ol>
<li> This is an enumerated list (first item).
<li> Continuing with the second item.
<li> foo
<li> bar
<li> Another
<li> List
</ol>
<p>
Line blocks are also a form of list:
</p>
<ol>
<li> This is the first line. The line continues here.
<li> This is the second line.
</ol>
----------------------------------------------------------------------
== options ==
60 column format:
----------------------------------------------------------------------
There is support for simple option lists, but only with long
options:
-X --exclude filter an option with a short and long option
with an argument
-I --include an option with both a short option and
a long option
--all Output all.
--both Output both (this description is quite
long).
--long Output all day long.
--par This option has two paragraphs in its
description. This is the first.
This is the second. Blank lines may
be omitted between options (as above)
or left in (as here).
The next paragraph looks like an option list, but lacks the
two-space marker after the option. It is treated as a normal
paragraph:
--foo bar baz
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
There is support for simple
option lists, but only with
long options:
-X --exclude filter an
option
with a
short
and
long
option
with an
argumen
t
-I --include an
option
with
both a
short
option
and a
long
option
--all Output
all.
--both Output
both
(this d
escript
ion is
quite
long).
--long Output
all day
long.
--par This
option
has two
paragra
phs in
its des
criptio
n. This
is the
first.
This is
the
second.
Blank
lines
may be
omitted
between
options
(as
above)
or left
in (as
here).
The next paragraph looks like
an option list, but lacks the
two-space marker after the
option. It is treated as a
normal paragraph:
--foo bar baz
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<p>
There is support for simple option lists,
but only with long options:
</p>
<dl>
<dt>-X --exclude filter
<dd>an option with a short and long option with an argument
<dt>-I --include
<dd>an option with both a short option and a long option
<dt> --all
<dd>Output all.
<dt> --both
<dd>Output both (this description is quite long).
<dt> --long
<dd>Output all day long.
<dt> --par
<dd>This option has two paragraphs in its description. This is the first.
<p>
This is the second. Blank lines may be omitted between
options (as above) or left in (as here).
</p>
</dl>
<p>
The next paragraph looks like an option list, but lacks the two-space
marker after the option. It is treated as a normal paragraph:
</p>
<p>
--foo bar baz
</p>
----------------------------------------------------------------------
== fields ==
60 column format:
----------------------------------------------------------------------
a First item.
ab Second item. Indentation and wrapping is
handled automatically.
Next list:
small The larger key below triggers full indentation
here.
much too large
This key is big enough to get its own line.
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
a First item.
ab Second item.
Indentation and
wrapping is
handled
automatically.
Next list:
small The larger key
below triggers
full indentation
here.
much too large
This key is big
enough to get
its own line.
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<dl>
<dt>a
<dd>First item.
<dt>ab
<dd>Second item. Indentation and wrapping is handled automatically.
</dl>
<p>
Next list:
</p>
<dl>
<dt>small
<dd>The larger key below triggers full indentation here.
<dt>much too large
<dd>This key is big enough to get its own line.
</dl>
----------------------------------------------------------------------
== containers (normal) ==
60 column format:
----------------------------------------------------------------------
Normal output.
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
Normal output.
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<p>
Normal output.
</p>
----------------------------------------------------------------------
== containers (verbose) ==
60 column format:
----------------------------------------------------------------------
Normal output.
Verbose output.
----------------------------------------------------------------------
['debug', 'debug']
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
Normal output.
Verbose output.
----------------------------------------------------------------------
['debug', 'debug']
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<p>
Normal output.
</p>
<p>
Verbose output.
</p>
----------------------------------------------------------------------
['debug', 'debug']
----------------------------------------------------------------------
== containers (debug) ==
60 column format:
----------------------------------------------------------------------
Normal output.
Initial debug output.
----------------------------------------------------------------------
['verbose']
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
Normal output.
Initial debug output.
----------------------------------------------------------------------
['verbose']
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<p>
Normal output.
</p>
<p>
Initial debug output.
</p>
----------------------------------------------------------------------
['verbose']
----------------------------------------------------------------------
== containers (verbose debug) ==
60 column format:
----------------------------------------------------------------------
Normal output.
Initial debug output.
Verbose output.
Debug output.
----------------------------------------------------------------------
[]
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
Normal output.
Initial debug output.
Verbose output.
Debug output.
----------------------------------------------------------------------
[]
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<p>
Normal output.
</p>
<p>
Initial debug output.
</p>
<p>
Verbose output.
</p>
<p>
Debug output.
</p>
----------------------------------------------------------------------
[]
----------------------------------------------------------------------
== roles ==
60 column format:
----------------------------------------------------------------------
Please see "hg add".
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
Please see "hg add".
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<p>
Please see "hg add".
</p>
----------------------------------------------------------------------
== sections ==
60 column format:
----------------------------------------------------------------------
Title
=====
Section
-------
Subsection
''''''''''
Markup: "foo" and "hg help"
---------------------------
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
Title
=====
Section
-------
Subsection
''''''''''
Markup: "foo" and "hg help"
---------------------------
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<h1>Title</h1>
<h2>Section</h2>
<h3>Subsection</h3>
<h2>Markup: "foo" and "hg help"</h2>
----------------------------------------------------------------------
== admonitions ==
60 column format:
----------------------------------------------------------------------
Note:
This is a note
- Bullet 1
- Bullet 2
Warning!
This is a warning Second input line of warning
!Danger!
This is danger
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
Note:
This is a note
- Bullet 1
- Bullet 2
Warning!
This is a warning Second
input line of warning
!Danger!
This is danger
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<p>
<b>Note:</b>
</p>
<p>
This is a note
</p>
<ul>
<li> Bullet 1
<li> Bullet 2
</ul>
<p>
<b>Warning!</b> This is a warning Second input line of warning
</p>
<p>
<b>!Danger!</b> This is danger
</p>
----------------------------------------------------------------------
== comments ==
60 column format:
----------------------------------------------------------------------
Some text.
Some indented text.
Empty comment above
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
Some text.
Some indented text.
Empty comment above
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<p>
Some text.
</p>
<p>
Some indented text.
</p>
<p>
Empty comment above
</p>
----------------------------------------------------------------------
=== === ========================================
a b c
=== === ========================================
1 2 3
foo bar baz this list is very very very long man
=== === ========================================
== table ==
60 column format:
----------------------------------------------------------------------
a b c
------------------------------------------------
1 2 3
foo bar baz this list is very very very long man
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
a b c
------------------------------
1 2 3
foo bar baz this list is
very very very long
man
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<table>
<tr><td>a</td>
<td>b</td>
<td>c</td></tr>
<tr><td>1</td>
<td>2</td>
<td>3</td></tr>
<tr><td>foo</td>
<td>bar</td>
<td>baz this list is very very very long man</td></tr>
</table>
----------------------------------------------------------------------
= ==== ======================================
s long line goes on here
xy tried to fix here by indenting
= ==== ======================================
== table+nl ==
60 column format:
----------------------------------------------------------------------
s long line goes on here
xy tried to fix here by indenting
----------------------------------------------------------------------
30 column format:
----------------------------------------------------------------------
s long line goes on here
xy tried to fix here by
indenting
----------------------------------------------------------------------
html format:
----------------------------------------------------------------------
<table>
<tr><td>s</td>
<td>long</td>
<td>line goes on here</td></tr>
<tr><td></td>
<td>xy</td>
<td>tried to fix here by indenting</td></tr>
</table>
----------------------------------------------------------------------