wireproto: compress data from a generator
Currently, the "getbundle" wire protocol command obtains a generator of
data, converts it to a util.chunkbuffer, then converts it back to a
generator via the protocol's groupchunks() implementation. For the SSH
protocol, groupchunks() simply reads 4kb chunks then write()s the
data to a file descriptor. For the HTTP protocol, groupchunks() reads
32kb chunks, feeds those into a zlib compressor, emits compressed data
as it is available, and that is sent to the WSGI layer, where it is
likely turned into HTTP chunked transfer chunks as is or further
buffered and turned into a larger chunk.
For both the SSH and HTTP protocols, there is inefficiency from using
util.chunkbuffer.
For SSH, emitting consistent 4kb chunks sounds nice. However, the file
descriptor it is writing to is almost certainly buffered. That means
that a Python .write() probably doesn't translate into exactly what is
written to the I/O layer.
For HTTP, we're going through an intermediate layer to zlib compress
data. So all util.chunkbuffer is doing is ensuring that the chunks we
feed into the zlib compressor are of uniform size. This means more CPU
time in Python buffering and emitting chunks in util.chunkbuffer but
fewer function calls to zlib.
This patch introduces and implements a new wire protocol abstract
method: compresschunks(). It is like groupchunks() except it operates
on a generator instead of something with a .read(). The SSH
implementation simply proxies chunks. The HTTP implementation uses
zlib compression.
To avoid duplicate code, the HTTP groupchunks() has been reimplemented
in terms of compresschunks().
To prove this all works, the "getbundle" wire protocol command has been
switched to compresschunks(). This removes the util.chunkbuffer from
that command. Now, data essentially streams straight from the
changegroup emitter to the wire, possibly through a zlib compressor.
Generators all the way, baby.
There were slim to no performance changes on the server as measured
with the mozilla-central repository. This is likely because CPU
time is dominated by reading revlogs, producing the changegroup, and
zlib compressing the output stream. Still, this brings us a little
closer to our ideal of using generators everywhere.
Create configuration
$ echo "[ui]" >> $HGRCPATH
$ echo "interactive=true" >> $HGRCPATH
help record (no record)
$ hg help record
record extension - commands to interactively select changes for
commit/qrefresh (DEPRECATED)
(use 'hg help extensions' for information on enabling extensions)
help qrecord (no record)
$ hg help qrecord
'qrecord' is provided by the following extension:
record commands to interactively select changes for commit/qrefresh
(DEPRECATED)
(use 'hg help extensions' for information on enabling extensions)
$ echo "[extensions]" >> $HGRCPATH
$ echo "record=" >> $HGRCPATH
help record (record)
$ hg help record
hg record [OPTION]... [FILE]...
interactively select changes to commit
If a list of files is omitted, all changes reported by 'hg status' will be
candidates for recording.
See 'hg help dates' for a list of formats valid for -d/--date.
You will be prompted for whether to record changes to each modified file,
and for files with multiple changes, for each change to use. For each
query, the following responses are possible:
y - record this change
n - skip this change
e - edit this change manually
s - skip remaining changes to this file
f - record remaining changes to this file
d - done, skip remaining changes and files
a - record all changes to all remaining files
q - quit, recording no changes
? - display help
This command is not available when committing a merge.
(use 'hg help -e record' to show help for the record extension)
options ([+] can be repeated):
-A --addremove mark new/missing files as added/removed before
committing
--close-branch mark a branch head as closed
--amend amend the parent of the working directory
-s --secret use the secret phase for committing
-e --edit invoke editor on commit messages
-I --include PATTERN [+] include names matching the given patterns
-X --exclude PATTERN [+] exclude names matching the given patterns
-m --message TEXT use text as commit message
-l --logfile FILE read commit message from file
-d --date DATE record the specified date as commit date
-u --user USER record the specified user as committer
-S --subrepos recurse into subrepositories
-w --ignore-all-space ignore white space when comparing lines
-b --ignore-space-change ignore changes in the amount of white space
-B --ignore-blank-lines ignore changes whose lines are all blank
(some details hidden, use --verbose to show complete help)
help (no mq, so no qrecord)
$ hg help qrecord
hg qrecord [OPTION]... PATCH [FILE]...
interactively record a new patch
See 'hg help qnew' & 'hg help record' for more information and usage.
(some details hidden, use --verbose to show complete help)
$ hg init a
qrecord (mq not present)
$ hg -R a qrecord
hg qrecord: invalid arguments
hg qrecord [OPTION]... PATCH [FILE]...
interactively record a new patch
(use 'hg qrecord -h' to show more help)
[255]
qrecord patch (mq not present)
$ hg -R a qrecord patch
abort: 'mq' extension not loaded
[255]
help (bad mq)
$ echo "mq=nonexistent" >> $HGRCPATH
$ hg help qrecord
*** failed to import extension mq from nonexistent: [Errno *] * (glob)
hg qrecord [OPTION]... PATCH [FILE]...
interactively record a new patch
See 'hg help qnew' & 'hg help record' for more information and usage.
(some details hidden, use --verbose to show complete help)
help (mq present)
$ sed 's/mq=nonexistent/mq=/' $HGRCPATH > hgrc.tmp
$ mv hgrc.tmp $HGRCPATH
$ hg help qrecord
hg qrecord [OPTION]... PATCH [FILE]...
interactively record a new patch
See 'hg help qnew' & 'hg help record' for more information and usage.
options ([+] can be repeated):
-e --edit invoke editor on commit messages
-g --git use git extended diff format
-U --currentuser add "From: <current user>" to patch
-u --user USER add "From: <USER>" to patch
-D --currentdate add "Date: <current date>" to patch
-d --date DATE add "Date: <DATE>" to patch
-I --include PATTERN [+] include names matching the given patterns
-X --exclude PATTERN [+] exclude names matching the given patterns
-m --message TEXT use text as commit message
-l --logfile FILE read commit message from file
-w --ignore-all-space ignore white space when comparing lines
-b --ignore-space-change ignore changes in the amount of white space
-B --ignore-blank-lines ignore changes whose lines are all blank
--mq operate on patch repository
(some details hidden, use --verbose to show complete help)
$ cd a
Base commit
$ cat > 1.txt <<EOF
> 1
> 2
> 3
> 4
> 5
> EOF
$ cat > 2.txt <<EOF
> a
> b
> c
> d
> e
> f
> EOF
$ mkdir dir
$ cat > dir/a.txt <<EOF
> hello world
>
> someone
> up
> there
> loves
> me
> EOF
$ hg add 1.txt 2.txt dir/a.txt
$ hg commit -m 'initial checkin'
Changing files
$ sed -e 's/2/2 2/;s/4/4 4/' 1.txt > 1.txt.new
$ sed -e 's/b/b b/' 2.txt > 2.txt.new
$ sed -e 's/hello world/hello world!/' dir/a.txt > dir/a.txt.new
$ mv -f 1.txt.new 1.txt
$ mv -f 2.txt.new 2.txt
$ mv -f dir/a.txt.new dir/a.txt
Whole diff
$ hg diff --nodates
diff -r 1057167b20ef 1.txt
--- a/1.txt
+++ b/1.txt
@@ -1,5 +1,5 @@
1
-2
+2 2
3
-4
+4 4
5
diff -r 1057167b20ef 2.txt
--- a/2.txt
+++ b/2.txt
@@ -1,5 +1,5 @@
a
-b
+b b
c
d
e
diff -r 1057167b20ef dir/a.txt
--- a/dir/a.txt
+++ b/dir/a.txt
@@ -1,4 +1,4 @@
-hello world
+hello world!
someone
up
qrecord with bad patch name, should abort before prompting
$ hg qrecord .hg
abort: patch name cannot begin with ".hg"
[255]
qrecord a.patch
$ hg qrecord -d '0 0' -m aaa a.patch <<EOF
> y
> y
> n
> y
> y
> n
> EOF
diff --git a/1.txt b/1.txt
2 hunks, 2 lines changed
examine changes to '1.txt'? [Ynesfdaq?] y
@@ -1,3 +1,3 @@
1
-2
+2 2
3
record change 1/4 to '1.txt'? [Ynesfdaq?] y
@@ -3,3 +3,3 @@
3
-4
+4 4
5
record change 2/4 to '1.txt'? [Ynesfdaq?] n
diff --git a/2.txt b/2.txt
1 hunks, 1 lines changed
examine changes to '2.txt'? [Ynesfdaq?] y
@@ -1,5 +1,5 @@
a
-b
+b b
c
d
e
record change 3/4 to '2.txt'? [Ynesfdaq?] y
diff --git a/dir/a.txt b/dir/a.txt
1 hunks, 1 lines changed
examine changes to 'dir/a.txt'? [Ynesfdaq?] n
After qrecord a.patch 'tip'"
$ hg tip -p
changeset: 1:5d1ca63427ee
tag: a.patch
tag: qbase
tag: qtip
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: aaa
diff -r 1057167b20ef -r 5d1ca63427ee 1.txt
--- a/1.txt Thu Jan 01 00:00:00 1970 +0000
+++ b/1.txt Thu Jan 01 00:00:00 1970 +0000
@@ -1,5 +1,5 @@
1
-2
+2 2
3
4
5
diff -r 1057167b20ef -r 5d1ca63427ee 2.txt
--- a/2.txt Thu Jan 01 00:00:00 1970 +0000
+++ b/2.txt Thu Jan 01 00:00:00 1970 +0000
@@ -1,5 +1,5 @@
a
-b
+b b
c
d
e
After qrecord a.patch 'diff'"
$ hg diff --nodates
diff -r 5d1ca63427ee 1.txt
--- a/1.txt
+++ b/1.txt
@@ -1,5 +1,5 @@
1
2 2
3
-4
+4 4
5
diff -r 5d1ca63427ee dir/a.txt
--- a/dir/a.txt
+++ b/dir/a.txt
@@ -1,4 +1,4 @@
-hello world
+hello world!
someone
up
qrecord b.patch
$ hg qrecord -d '0 0' -m bbb b.patch <<EOF
> y
> y
> y
> y
> EOF
diff --git a/1.txt b/1.txt
1 hunks, 1 lines changed
examine changes to '1.txt'? [Ynesfdaq?] y
@@ -1,5 +1,5 @@
1
2 2
3
-4
+4 4
5
record change 1/2 to '1.txt'? [Ynesfdaq?] y
diff --git a/dir/a.txt b/dir/a.txt
1 hunks, 1 lines changed
examine changes to 'dir/a.txt'? [Ynesfdaq?] y
@@ -1,4 +1,4 @@
-hello world
+hello world!
someone
up
record change 2/2 to 'dir/a.txt'? [Ynesfdaq?] y
After qrecord b.patch 'tip'
$ hg tip -p
changeset: 2:b056198bf878
tag: b.patch
tag: qtip
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: bbb
diff -r 5d1ca63427ee -r b056198bf878 1.txt
--- a/1.txt Thu Jan 01 00:00:00 1970 +0000
+++ b/1.txt Thu Jan 01 00:00:00 1970 +0000
@@ -1,5 +1,5 @@
1
2 2
3
-4
+4 4
5
diff -r 5d1ca63427ee -r b056198bf878 dir/a.txt
--- a/dir/a.txt Thu Jan 01 00:00:00 1970 +0000
+++ b/dir/a.txt Thu Jan 01 00:00:00 1970 +0000
@@ -1,4 +1,4 @@
-hello world
+hello world!
someone
up
After qrecord b.patch 'diff'
$ hg diff --nodates
$ cd ..