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Andy Delcambre
sadelcambre
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YAPC:Asia
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I don’t
write Perl
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I rarely
write Perl
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Total source lines grouped by
language:
!
ruby: 316613 (98.99%)
sh: 2268 (0.71%)
ansic: 743 (0.23%)
perl: 179 (0.06%)
python: 31 (0.01%)
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DIRECTED
ACYCLIC
GRAPH
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$ git log
commit b3f13c1
Author: Andy Delcambre
Date: Thu Aug 28 08:29 2014
!
Commit 3
!
commit c79e797
Author: Andy Delcambre
Date: Thu Aug 28 08:29 2014
!
Commit 2
!
commit 9a42679
Author: Andy Delcambre
Date: Thu Aug 28 08:28 2014
!
Initial commit
commit b3f13c1
Commit 3
commit c79e797
Commit 2
commit 9a42679
Initial commit
HEAD
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$ git cat-file -p b3f13c1
tree 9e68447
parent c79e797
author Andy Delcambre 1409182168
committer Andy Delcambre 1409182168
!
Commit 3
commit b3f13c1
Commit 3
tree 9e68447
commit c79e797
Commit 2
Parent
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$ git cat-file -p 9e68447
100644 blob b465ded README.md
commit b3f13c1
Commit 3
tree 9e68447
commit c79e797
Commit 2
Parent
blob 9e68447
README.md
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$ git cat-file -p b465ded
# Test
!
A test repo, for YAPC:Asia.
commit b3f13c1
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tree 9e68447
commit c79e797
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blob 9e68447
README.md
# Test
!
A test repo, for YAPC:Asia.
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GitHub
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Hosting a Git repo is
Secret:
EASY
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enzo $ git init --bare demo.git
Initialized empty Git repo in /home/adelcambre/git/demo.git/
!
yt $ git remote add origin adelcambre@enzo:git/demo.git
yt $ git push origin master
Counting objects: 6, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (6/6), 473 bytes, done.
Total 6 (delta 0), reused 6 (delta 0)
To adelcambre@enzo:git/demo.git
* [new branch] master -> master
!
yt $ git clone adelcambre@enzo:git/demo.git
Cloning into 'demo'...
remote: Counting objects: 6, done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 6 (delta 0), reused 0 (delta 0)
Receiving objects: 100% (6/6), done.
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yt $ git remote add -f origin [email protected]:adelcambre/demo.git
Updating origin
From github.com:adelcambre/demo
* [new branch] master -> origin/master
!
yt $ git push origin master
Counting objects: 6, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (6/6), 473 bytes, done.
Total 6 (delta 0), reused 6 (delta 0)
To https://github.com/adelcambre/demo.git
* [new branch] master -> master
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Hosting a *lot* of Git repos is
Not so Secret:
HARD
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> 7 million
repositories
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1.5 million
pushes
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100 million
pulls & clones
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27
fileservers
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100 TB of
online storage
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Grit
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1st Commit
GitHub
1st Commit
Grit
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Ruby
wrapper around
Git
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repo = Grit::Repo.new(“grit.git”)
!
repo.commits
# => [#,
#,
#,
#,
#]
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This works for
everything!
!
(locally)
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27
fileservers
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Smoke
“Grit in the cloud”
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The
Internet
Chimney
fs102
fs103
fs104
fs105
…
fe102
fe103
fe104
fe105
…
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module Smoke
def self.install!
::Grit.send(:remove_const,
:Git)
!
::Grit.const_set(:Git,
Smoke::Git)
end
end
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ls_tree("HEAD").each do |entry|
if entry.blob?
load_blob(entry.oid)
end
end
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Death by
Round Trip
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A condensed
(and probably wrong)
history of git
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Bitkeeper
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Git
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Shared library?
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libgit2
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JGit
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libgit2
http://github.com/libgit2/libgit2
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Rugged
http://github.com/libgit2/rugged
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Ruby
wrapper around
libgit2
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repo =
Rugged::Repository.new("rugged.git")
!
repo.last_commit
# => #
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Perl
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Git-Raw
https://metacpan.org/release/Git-Raw
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GitRPC
The New Hotness
aka
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Like Smoke,
But Better
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Caching
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Pluggable
Wire Protocols
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Encoding
Aware
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GIT(1) Git Manual GIT(1)
!
NAME
git - the stupid content tracker
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GIT(1) Git Manual GIT(1)
!
NAME
git - the stupid content tracker
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Git doesn’t
care about
encodings
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Smoke
doesn’t either
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GitRPC is
encoding aware
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Detect and tag
as soon as possible
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The Switch
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class Repository
def git
Smoke::Repo.new(path)
end
!
def rpc
GitRPC.new(path)
end
end
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Graphite
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Graph Every Call
Both GitRPC
and Smoke
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1 Year ago
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Where are
we today?
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Good Progress
But not done yet
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Finding the
Final 0.1%
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Backscatter
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Call Counting
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def git
backscatter_measure
Smoke::Repo.new(path)
end
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Method
Tracing
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def git
backscatter_trace 20
Smoke::Repo.new(path)
end
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Recap
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Run both
concurrently
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Measure
Everything
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Use tracing to
find the last
0.1%
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Andy Delcambre
sadelcambre
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Further Reading
Git for Computer Scientists
http://eagain.net/articles/git-for-computer-scientists/
My mom told me git doesn’t scale
https://vimeo.com/64716825
How GitHub uses GitHub to build Github
http://zachholman.com/talk/how-github-uses-github-to-build-github/