Cogito Tutorial If It Helps

Cogito Tutorial If It Helps

[James Purser]

I reworked the previous tutorial to take in the changes in the scripts.
Will make this a series of tutorials to cover all aspects. Any
suggestions or hints or spelling corrections would be most welcome.

http://ksit.dynalias.com/articles.php?s_id=46&art_id=41
-- 
James Purser
http://ksit.dynalias.com

Re: Cogito Tutorial If It Helps

[Petr Baudis]

Dear diary, on Tue, Apr 26, 2005 at 10:52:27PM CEST, I got a letter
where James Purser <purserj@ksit.dynalias.com> told me that...
> I reworked the previous tutorial to take in the changes in the scripts.
> Will make this a series of tutorials to cover all aspects. Any
> suggestions or hints or spelling corrections would be most welcome.
> 
> http://ksit.dynalias.com/articles.php?s_id=46&art_id=41

Thanks for writing that! :-)

I'd vote for describing the cg-update right near cg-pull, or perhaps
even before cg-update, as the primary method; I think it's commonly what
people really want to do when they do cg-pull anyway.

cg-merge is _not_ like doing cg-diff | cg-patch - that's a dangerous
thought, and not true at all. cg-diff | cg-patch will just apply the
given diff to your working directory, but it won't record any merging
metadata, will often get it very wrong, and you will get to all sorts of
other troubles. Just always use cg-merge. And probably pass it -b only
when you know what are you doing.

Thanks,

-- 
				Petr "Pasky" Baudis
Stuff: http://pasky.or.cz/
C++: an octopus made by nailing extra legs onto a dog. -- Steve Taylor

Re: Cogito Tutorial If It Helps

[James Purser]

On Wed, 2005-04-27 at 07:18, Petr Baudis wrote:
> Dear diary, on Tue, Apr 26, 2005 at 10:52:27PM CEST, I got a letter
> where James Purser <purserj@ksit.dynalias.com> told me that...
> > I reworked the previous tutorial to take in the changes in the scripts.
> > Will make this a series of tutorials to cover all aspects. Any
> > suggestions or hints or spelling corrections would be most welcome.
> > 
> > http://ksit.dynalias.com/articles.php?s_id=46&art_id=41
> 
> Thanks for writing that! :-)
> 
> I'd vote for describing the cg-update right near cg-pull, or perhaps
> even before cg-update, as the primary method; I think it's commonly what
> people really want to do when they do cg-pull anyway.
> 
> cg-merge is _not_ like doing cg-diff | cg-patch - that's a dangerous
> thought, and not true at all. cg-diff | cg-patch will just apply the
> given diff to your working directory, but it won't record any merging
> metadata, will often get it very wrong, and you will get to all sorts of
> other troubles. Just always use cg-merge. And probably pass it -b only
> when you know what are you doing.
> 
> Thanks,

Thanks for that, I've changed it a little to point out that cg-patch
should really only be used for small single file patches.
-- 
James Purser
http://ksit.dynalias.com

Re: Cogito Tutorial If It Helps

[Petr Baudis]

Dear diary, on Tue, Apr 26, 2005 at 11:36:43PM CEST, I got a letter
where James Purser <purserj@ksit.dynalias.com> told me that...
> On Wed, 2005-04-27 at 07:18, Petr Baudis wrote:
> > cg-merge is _not_ like doing cg-diff | cg-patch - that's a dangerous
> > thought, and not true at all. cg-diff | cg-patch will just apply the
> > given diff to your working directory, but it won't record any merging
> > metadata, will often get it very wrong, and you will get to all sorts of
> > other troubles. Just always use cg-merge. And probably pass it -b only
> > when you know what are you doing.
> 
> Thanks for that, I've changed it a little to point out that cg-patch
> should really only be used for small single file patches.

No, you've missed the point. It isn't the size of the change what
matters - cg-patch should handle even huge patches (mostly) fine.  What
matters is that you just did was not merge. It was applying some patch
to your working tree, but not merging branches.

So after doing cg-diff | cg-patch several times, you have your working
tree full of huge local changes (making it impossible to sensibly
cg-merge) and your last commit happenned long ago. Or you commit the
cg-patch results, but your commits are wrong, since they don't carry the
appropriate merge information.

-- 
				Petr "Pasky" Baudis
Stuff: http://pasky.or.cz/
C++: an octopus made by nailing extra legs onto a dog. -- Steve Taylor

Re: Cogito Tutorial If It Helps

[Alan Chandler]

On Tuesday 26 April 2005 21:52, James Purser wrote:
> I reworked the previous tutorial to take in the changes in the scripts.
> Will make this a series of tutorials to cover all aspects. Any
> suggestions or hints or spelling corrections would be most welcome.
>
> http://ksit.dynalias.com/articles.php?s_id=46&art_id=41

Although I have been reading this mailing list since almost the beginning, I 
have not had a chance to download and try anything.  Using this message as an 
incentive to start, I started to follow this.

However I have run into problems.  

Let me try and explain.

The first part of the tutorial of loading the tarball and building things is 
fine (should be, its a well trodden mental model) - and actually for me I did 
not have libcurl3-dev installed the first time - but because I already had 
the mental model in my mind on this stage it was easy to fit.

I then issued the cg-clone command to get a fresh copy of cogito.  This is 
where I think it would be useful to take time-out from the tutorial and 
explain what I have here.  For me at least, if I don't have a mental model of 
what is happening, I am totally confused.

I "think" I understand the git repository with the various content addressable 
objects.  Reading the README file describes that quite well.  I assume that 
is what is stored in the .git subdirectory (although I have yet to find any 
text that formally says that).

Where I am confused is the relationship between what is in the .git 
subdirectory and the project tree of cogito that sits around it.  Obviously I 
understand that its the latest version of the project as represented by the 
objects in the repository, but what I don't really understand (and neither 
your tutorial nor all the explanations of each of the commands in the README 
really explain it either) is how the various commands adjust the 
relationship.

For instance cg-branch-add seems to add a branch to the repository from a url 
(I assume it downloads any "blobs" etc that are not already in my local 
repository and creates a tag that identifies the head of a tree object), but 
a don't understand how I am supposed see that particular branch as expanded 
code.  (I suspect it might be cg-seek, but I am not really sure - and if it 
is how do you find out what branch this expanded code is now pointed to?).  
But what do cg-update and cg-pull do in terms of the uncompressed code 
sitting in the surrounding directory round the repository, particularly when 
you perform them on a branch that is not the one that the code refers to.  


The reason I raise all this, is when I follow through on your tutorial and get 
to the cg-diff stage I get this

xargs: cg-Xdiffdo: No such file or directory

And I have absolutely no idea whats wrong or where to start looking.



-- 
Alan Chandler
http://www.chandlerfamily.org.uk

Re: Cogito Tutorial If It Helps

[Petr Baudis]

Dear diary, on Wed, Apr 27, 2005 at 08:22:07PM CEST, I got a letter
where Alan Chandler <alan@chandlerfamily.org.uk> told me that...
> Where I am confused is the relationship between what is in the .git 
> subdirectory and the project tree of cogito that sits around it.  Obviously I 
> understand that its the latest version of the project as represented by the 
> objects in the repository, but what I don't really understand (and neither 
> your tutorial nor all the explanations of each of the commands in the README 
> really explain it either) is how the various commands adjust the 
> relationship.
> 
> For instance cg-branch-add seems to add a branch to the repository from a url 
> (I assume it downloads any "blobs" etc that are not already in my local 
> repository and creates a tag that identifies the head of a tree object), but 
> a don't understand how I am supposed see that particular branch as expanded 
> code.  (I suspect it might be cg-seek, but I am not really sure - and if it 
> is how do you find out what branch this expanded code is now pointed to?).  
> But what do cg-update and cg-pull do in terms of the uncompressed code 
> sitting in the surrounding directory round the repository, particularly when 
> you perform them on a branch that is not the one that the code refers to.  

Those commands affect your working tree:

	cg-cancel
		Cancels out any modifications in the working tree w.r.t.
		the last commit
	cg-merge
		Merges changes done in another branch to your current
		branch
	cg-patch
		Applies a patch, with regard to special git-specific
		info generated by cg-diff
	cg-rm
		Removed the file from your working tree if it's still
		around
	cg-seek
		Changes your working tree to match some other commit in
		the database
	cg-update
		Potentially brings in changes from a remote branch, and
		updates your working tree to the latest commit + those
		changes

Those commands affect the objects database:

	cg-commit
	cg-pull
		cg-pull just gets the data from remote objects database
		to the local objects database; it is the "first part"
		of what cg-update does
	cg-update

This affects both:

	cg-merge
		Not directly, but it can call cg-commit automatically.
	cg-update

> The reason I raise all this, is when I follow through on your tutorial and get 
> to the cg-diff stage I get this
> 
> xargs: cg-Xdiffdo: No such file or directory
> 
> And I have absolutely no idea whats wrong or where to start looking.

You didn't do make install and you don't have the cogito tree in your $PATH.

-- 
				Petr "Pasky" Baudis
Stuff: http://pasky.or.cz/
C++: an octopus made by nailing extra legs onto a dog. -- Steve Taylor

Re: Cogito Tutorial If It Helps

[Alan Chandler]

On Wednesday 27 April 2005 20:32, Petr Baudis wrote:

> Those commands affect your working tree:
>
> 	cg-cancel
> 		Cancels out any modifications in the working tree w.r.t.
> 		the last commit
> 	cg-merge
> 		Merges changes done in another branch to your current
> 		branch
> 	cg-patch
> 		Applies a patch, with regard to special git-specific
> 		info generated by cg-diff
> 	cg-rm
> 		Removed the file from your working tree if it's still
> 		around
> 	cg-seek
> 		Changes your working tree to match some other commit in
> 		the database
> 	cg-update
> 		Potentially brings in changes from a remote branch, and
> 		updates your working tree to the latest commit + those
> 		changes
>
> Those commands affect the objects database:
>
> 	cg-commit
> 	cg-pull
> 		cg-pull just gets the data from remote objects database
> 		to the local objects database; it is the "first part"
> 		of what cg-update does
> 	cg-update
>
> This affects both:
>
> 	cg-merge
> 		Not directly, but it can call cg-commit automatically.
> 	cg-update


Thanks - that makes things a lot clearer

>
> > The reason I raise all this, is when I follow through on your tutorial
> > and get to the cg-diff stage I get this
> >
> > xargs: cg-Xdiffdo: No such file or directory
> >
> > And I have absolutely no idea whats wrong or where to start looking.
>
> You didn't do make install and you don't have the cogito tree in your
> $PATH.

I DID do a make install - which put everything in ~/bin (including cg-Xdiffdo) 
and ~/bin is the first item in my $PATH.


-- 
Alan Chandler
http://www.chandlerfamily.org.uk

Re: Cogito Tutorial If It Helps

[Alan Chandler]

On Wednesday 27 April 2005 23:15, Alan Chandler wrote:
> On Wednesday 27 April 2005 20:32, Petr Baudis wrote:

> > You didn't do make install and you don't have the cogito tree in your
> > $PATH.
>
> I DID do a make install - which put everything in ~/bin (including
> cg-Xdiffdo) and ~/bin is the first item in my $PATH.

Thanks to James Purser its fixed.

I needed the full path to ~/bin rather than just using the ~ in $PATH.
-- 
Alan Chandler
http://www.chandlerfamily.org.uk

Re: Cogito Tutorial If It Helps

[Benjamin Herrenschmidt]

On Wed, 2005-04-27 at 06:52 +1000, James Purser wrote:
> I reworked the previous tutorial to take in the changes in the scripts.
> Will make this a series of tutorials to cover all aspects. Any
> suggestions or hints or spelling corrections would be most welcome.
> 
> http://ksit.dynalias.com/articles.php?s_id=46&art_id=41

Hrm... this tutorial is exactly like cogito's own readme as far as I'm
concerned : it just makes things even more confusing to me. I must be
really stupid, I should stick to hacking the kernel and not try to use
userland tools :)

Anyway, can you explain what it is all about this branch thing ?

I don't understand why in hell you would want linux-2.6 to be a branch
of cogito itself ... 

Ben.

Re: Cogito Tutorial If It Helps

[Benjamin Herrenschmidt]

On Thu, 2005-04-28 at 10:48 +1000, Benjamin Herrenschmidt wrote:
> On Wed, 2005-04-27 at 06:52 +1000, James Purser wrote:
> > I reworked the previous tutorial to take in the changes in the scripts.
> > Will make this a series of tutorials to cover all aspects. Any
> > suggestions or hints or spelling corrections would be most welcome.
> > 
> > http://ksit.dynalias.com/articles.php?s_id=46&art_id=41
> 
> Hrm... this tutorial is exactly like cogito's own readme as far as I'm
> concerned : it just makes things even more confusing to me. I must be
> really stupid, I should stick to hacking the kernel and not try to use
> userland tools :)
> 
> Anyway, can you explain what it is all about this branch thing ?
> 
> I don't understand why in hell you would want linux-2.6 to be a branch
> of cogito itself ... 

Forget it, I must be lacking caffeine this morning, you are adding linus
git, not linux-2.6 as a branch which  makes a lot more sense... sorry
for the noise.

Ben.

Re: Cogito Tutorial If It Helps

[James Purser]

Okay I sent a message in earlier but it must have been eaten by a grue
or something.

I have put in a little bit about the cg-update as well as describing
cg-patch but recommending cg-merge when dealing with different branches
due to the meta data problem.

Anything else you would like to see?
-- 
James Purser
Winnet Developer
+61 2 4223 4131
http://www.winnet.com.au