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   9                         <h1>Dscho's Git log</h1>
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  11                         <table width=400px bgcolor=#e0e0e0 border=0>
  12                         <tr><th>Table of contents:</th></tr>
  13                         <tr><td>
  14                         <p><ul>
  15                         <li><a href=#1249835938>09 Aug 2009 The dilemma of being correct</a>
  16                         <li><a href=#1245419588>19 Jun 2009 The GraphGUI project</a>
  17                         <li><a href=#1242408298>15 May 2009 Wasting way too much time on msysGit</a>
  18                         <li><a href=#1241995759>11 May 2009 Working on jgit diff</a>
  19                         <li><a href=#1239975597>17 Apr 2009 No time for Git</a>
  20                         <li><a href=#1238970571>06 Apr 2009 How to recover from a hackathon</a>
  21                         <li><a href=#1236554268>09 Mar 2009 So, what is missing from my <i>rebase-i-p</i> branch?</a>
  22                         <li><a href=#1236479389>08 Mar 2009 New Git for Windows version</a>
  23                         <li><a href=#1235092615>20 Feb 2009 Code reviews</a>
  24                         <li><a href=#1234409395>12 Feb 2009 Interactive <i>rebase</i> just learnt a new command: <i>topic</i></a>
  25                         </ul></p>
  26                         <a href=dscho.git?a=blob_plain;hb=d328cccacc66bc5d183790eebcf5a3334830ab55;f=index.html>Older posts</a>
  27                         </td></tr></table>
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  36                         <table width=400px bgcolor=#e0e0e0 border=0>
  37                         <tr><th>About this blog:</th></tr>
  38                         <tr><td>
  39                         <p>It is an active <a href=http://repo.or.cz/w/git/dscho.git?a=blob_plain;f=index.html;hb=5f002cab57a837125a8f901bcd1f3c1477bc3119>abuse</a> of <a href=http://repo.or.cz/>repo.or.cz</a>,
  40                         letting gitweb unpack the objects in the current tip of the branch <i>blog</i>,
  41                         including the images and the RSS feed.
  42                         </p><p>
  43                         Publishing means running a script that collects the posts, turns them into
  44                         HTML, makes sure all the images are checked in, and pushes the result.
  45                         </p><p>
  46                         This blog also serves to grace the world with Dscho's random thoughts on and
  47                         around Git.
  48                         </p>
  49                         </td></tr></table>
  50                         <br>
  51                         <table width=400px bgcolor=#e0e0e0 border=0>
  52                         <tr><th>Links:</th></tr>
  53                         <tr><td>
  54                         <ul>
  55                         <li> <a href=http://git-scm.com/>Git's homepage</a>
  56                         <li> <a href=http://gitster.livejournal.com/>Junio's blog</a>
  57                         <li> <a href=http://www.spearce.org/>Shawn's blog</a> seems to be sitting
  58                               idle ever since he started working for Google...
  59                         <li> <a href=http://torvalds-family.blogspot.com/>Linus' blog</a> does not
  60                               talk much about Git...
  61                         <li> Scott Chacon's <a href=http://whygitisbetterthanx.com/>Why Git is better
  62                              than X</a> site
  63                         <li> <a href=http://vilain.net/>The blog of mugwump</a>
  64                         <li> <a href=http://merlyn.vox.com/>Merlyn's blog</a>
  65                         <li> <a href=http://blogs.gnome.org/newren/>Elijah Newren</a> chose the
  66                               same path as Cogito, offering an alternative porcelain (an approach
  67                               that is doomed in my opinion)
  68                         <li> <a href=http://msysgit.googlecode.com/>The msysGit project</a>, a (mostly)
  69                               failed experiment to lure the many Windows developers out there to
  70                               contribute to Open Source for a change.
  71                         </ul>
  72                         </td></tr></table>
  73                         <br>
  74                         <table width=400px bgcolor=#e0e0e0 border=0>
  75                         <tr><th>Google Ads:</th></tr>
  76                         <tr><td>
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  88                         </td></tr></table>
  89                         </div>
  90                         <h6>Sunday, 9th of August, Anno Domini MMIX, at the hour of the Rooster</h6>
  91                         <a name=1249835938>
  92                         <h2>The dilemma of being correct</h2>
  93
  94                         <p>
  95                         </p><p>
  96                         So I am opinionated.  No news there.  The problem of being opinionated, though,
  97                         is that people do not take you seriously even if you are correct.
  98                         </p><p>
  99                         For example, I vividly remember having had concerns about the Git wrapper
 100                         being linked to <a href=http://curl.haxx.se/>cURL</a>, and I vividly remember
 101                         that our maintainer did not have such concerns and took Daniel's patch.  I could
 102                         not find proof of my public comment quickly enough to add a link here, though.
 103                         </p><p>
 104                         Alas, there are serious problems with being correct:
 105                         </p><p>
 106                         <ol>
 107                         <li>If you're correct, you waste a lot of time trying to convince people (but
 108                         they ignore you nevertheless),
 109                         <li>Other people are regularly p*ssed off, especially when they find out
 110                         (or even worse, when it is pointed out to them) that they were wrong, and
 111                         <li>You can buy <u>nothing</u> for having been correct.
 112                         </ol>
 113                         </p><p>
 114                         It is a lose-lose situation.
 115                         </p><p>
 116                         In the current context, I am pretty certain that the rev cache and the pack
 117                         index are so similar in nature that we'll find quite a few issues that we had
 118                         with one repeated with the other.
 119                         </p><p>
 120                         As I <u>hate</u> losing time over a discussion others try to "win" -- which
 121                         invariably means that they refuse to be convinced of anything disagreeing with
 122                         their opinion &#x263a; -- I will just shut up, and probably have one or two odd
 123                         feelings when it turns out I was right.
 124                         </p>
 125                         <h6>Friday, 19th of June, Anno Domini MMIX, at the hour of the Monkey</h6>
 126                         <a name=1245419588>
 127                         <h2>The GraphGUI project</h2>
 128
 129                         <p>
 130                         </p><p>
 131                         After a few unfortunate delays (and some fortunate ones, just not for us), the
 132                         GraphGUI project finally takes off.  A quick first glance:
 133                         </p><p>
 134                         <center><img src=dscho.git?a=blob_plain;hb=c33212b23b2b3e45c14403efe82cabb1cd53f6e3;f=basic-gui.jpg basic-gui.jpg></center>
 135                         </p><p>
 136                         The delays were a bit unnerving, but the student is really bright and still
 137                         has the chance to pull the project off.
 138                         </p><p>
 139                         Next plans are to show text, too, to invent a rudimentary layout engine that
 140                         can be adjusted manually (this is in contrast to <i>gitk</i> or <i>log --graph</i>).
 141                         </p><p>
 142                         After that, integration into JGit (this probably triggered the eGit/JGit
 143                         split).
 144                         </p><p>
 145                         And then we'll go wild!
 146                         </p>
 147                         <h6>Friday, 15th of May, Anno Domini MMIX, at the hour of the Dog</h6>
 148                         <a name=1242408298>
 149                         <h2>Wasting way too much time on msysGit</h2>
 150
 151                         <p>
 152                         </p><p>
 153                         I recently got into the bad habit of spending a large amount of my waking
 154                         hours working on msysGit, more than is really healthy for me.
 155                         </p><p>
 156                         For example, I spent the whole morning -- when I should have worked on a
 157                         very important day-job project -- on trying to fix issue 258, where
 158                         <i>git web--browse</i> does not work as expected because of quoting issues
 159                         with cmd.exe.
 160                         </p><p>
 161                         This is reducing my Git time budget to negative numbers, so much so that I
 162                         cannot even work on Git projects that I actually like, such as <i>jgit diff</i>
 163                         or <i>git rebase -i -p</i>, or at least projects I felt obliged to continue
 164                         to work on, such as <i>git notes</i>.
 165                         </p><p>
 166                         Now, some people who tried to teach me some time management strongly
 167                         criticized me for ignoring their lessons, and unfortunately, I have to agree.
 168                         </p><p>
 169                         The problem is that I would <u>hate</u> to see msysGit fall to the same state it
 170                         was after I stopped working on it last year.  I started it, and I would like
 171                         it to grow, but too few people took care of the issue tracker, too few tried
 172                         to debug their problems themselves, too few submitted fixes.
 173                         </p><p>
 174                         I note, though, that there is a positive trend.  But being the impatient person
 175                         I am ("2 seconds is my attention span") I tend to want the trend to be more
 176                         impressive.
 177                         </p><p>
 178                         Anyway, no work on msysGit for at least 4 days, that's what the doctor (me)
 179                         said...
 180                         </p>
 181                         <h6>Monday, 11th of May, Anno Domini MMIX, at the hour of the Rat</h6>
 182                         <a name=1241995759>
 183                         <h2>Working on jgit diff</h2>
 184
 185                         <p>
 186                         </p><p>
 187                         Shawn did so many useful things that I use on a daily basis that I felt really
 188                         awful when I realized just how <u>long</u> I had promised to clean up that diff
 189                         implementation I wrote for JGit.
 190                         </p><p>
 191                         Alas, it appears that the thing turned out to be almost a complete rewrite, as
 192                         the original implementation walked the edit graph in a rather inefficient way.
 193                         </p><p>
 194                         A little background: Myers' algorithm to generate "an edit script" works on
 195                         the <i>edit graph</i>: imagine you have all lines of file <i>A</i> as columns and
 196                         all lines of file <i>B</i> as rows, then the <i>edit graph</i> is a connection of
 197                         the upper left corner to the lower right corner, containing only horizontal,
 198                         vertical or diagonal elements, where diagonal elements are only allowed when
 199                         the lines of both files agree at that point:
 200                         </p><p>
 201 <pre>
 202  H E L L O , W O R L D
 203  ----
 204 L    \
 205       ---
 206 O        \
 207           ---
 208 W            \
 209               --------
 210 </pre>
 211                         </p><p>
 212                         The <i>shortest</i> edit path minimizes the number of non-diagonal elements.
 213                         </p><p>
 214                         Myers' idea is to develop forward and backward paths at the same time
 215                         (increasing the number of non-diagonal elements uniformly), storing
 216                         only the latest end points.  Once the paths meet, divide and conquer.
 217                         </p><p>
 218                         In theory, it would be quicker to store <u>all</u> end points and then just
 219                         reconstruct the shortest paths, alas, this takes way too much memory.
 220                         </p><p>
 221                         My first implementation did not remember start or end of the non-diagonal
 222                         parts, and had to recurse way more often than really necessary (in the end,
 223                         we will order the non-diagonal parts into horizontal and vertical parts
 224                         anyway, so start and end are sufficient).
 225                         </p><p>
 226                         The current progress can be seen <a href=http://repo.or.cz/w/egit/dscho.git/>
 227                         here</a>.
 228                         </p>
 229                         <h6>Friday, 17th of April, Anno Domini MMIX, at the hour of the Monkey</h6>
 230                         <a name=1239975597>
 231                         <h2>No time for Git</h2>
 232
 233                         <p>
 234                         </p><p>
 235                         It is a shame, but most of my Git time budget is taken by msysGit these
 236                         days.
 237                         </p><p>
 238                         But at least msysGit is moving again; I'll probably write a Herald about
 239                         it.
 240                         </p>
 241                         <h6>Monday, 6th of April, Anno Domini MMIX, at the hour of the Rat</h6>
 242                         <a name=1238970571>
 243                         <h2>How to recover from a hackathon</h2>
 244
 245                         <p>
 246                         </p><p>
 247                         Phew, 2 crazy and fantastic weeks are behind me.  But it takes its toll:
 248                         a weekend I was more offline than online.
 249                         </p><p>
 250                         Things that are important now: relax. sleep. take a walk. learn to sleep
 251                         more than 4 hours a night again. learn to watch a movie without thinking
 252                         about code. go for a run.
 253                         </p><p>
 254                         And after recovering, back to the rebase-i-p branch!
 255                         </p>
 256                         <h6>Monday, 9th of March, Anno Domini MMIX, at the hour of the Rat</h6>
 257                         <a name=1236554268>
 258                         <h2>So, what is missing from my <i>rebase-i-p</i> branch?</h2>
 259
 260                         <p>
 261                         </p><p>
 262                         I regularly use <i>rebase -i -p</i> these days, to update my personal Git
 263                         tree (which used to be <i>my-next</i>).
 264                         </p><p>
 265                         There are a few things missing before I can start assembling a patch
 266                         series for submission:
 267                         </p><p>
 268                         <ul>
 269                         <li>I need to handle the commit parents which are outside of the rebased
 270                         ones properly.  In other words, when a commit is picked whose parent is
 271                         not rebased, it needs to be rebased onto $ONTO.
 272                         <li>The patch which uses patch-id to generate DROPPED directly also tries to
 273                         consolidate the handling of DROPPED commits by putting them into REWRITTEN
 274                         instead of DROPPED, but that breaks the tests.  So, this patch needs to be
 275                         split.
 276                         <li>I want to introduce one more command, <i>rephrase</i>, which allows you to
 277                         modify the commit message, and nothing more, and <i>halt</i>, which does the
 278                         same as <i>edit</i> without <i>pick</i>.  Then there needs to be a new test script
 279                         for those commands, and this will be an early patch series.
 280                         <li>Time.  I need time, desperately.  If my day job was not as exciting as it
 281                         is, I would have more time for Git.  As it is, I have to budget my time so
 282                         that I get anything done at all.
 283                         </ul>
 284                         </p><p>
 285                         These issues have been postponed due to Steffen taking a well-deserved
 286                         vacation, which means that I have to act as msysGit maintainer again.
 287                         </p><p>
 288                         And this coming week, I will have other things to do in all likeliness, so
 289                         that I expect to be able to submit a <i>rebase -i -p</i> patch series only next
 290                         week.  If not then, due to a heavy workload, it will be postponed to early
 291                         April.
 292                         </p><p>
 293                         Oh well, the joys of being excited by several competing projects! &#x263a;
 294                         </p>
 295                         <h6>Sunday, 8th of March, Anno Domini MMIX, at the hour of the Tiger</h6>
 296                         <a name=1236479389>
 297                         <h2>New Git for Windows version</h2>
 298
 299                         <p>
 300                         </p><p>
 301                         Phew.  That was quite a day, almost exclusively spent on finishing that
 302                         installer.  The worst part: updating GCC seemed not to be such a good idea
 303                         after all...
 304                         </p><p>
 305                         For Windows, we need to use the printf format <i>%I64u</i> (which is
 306                         non-standard, in the common way of Microsoft) if you want to print 64-bit
 307                         wide unsigned numbers.  The rest of the world accepts the standard <i>%llu</i>.
 308                         </p><p>
 309                         After upgrading to the new GCC, a lot of warnings appeared, complaining
 310                         about <i>%I64u</i>.  The warnings went away when I replaced the format with
 311                         <i>%llu</i>.
 312                         </p><p>
 313                         Being the naive I am, I mistook that for a sign that we could finally go
 314                         more standards-compliant.
 315                         </p><p>
 316                         However, it only means that we have to live with the warnings for now, as
 317                         the C runtime provided on Windows still strongly disagrees with standards
 318                         (and it has to continue to do so, lest it break existing programs).
 319                         </p><p>
 320                         Sigh.
 321                         </p><p>
 322                         At least I have the feeling that I caught the most important bugs before
 323                         releasing.
 324                         </p>
 325                         <h6>Friday, 20th of February, Anno Domini MMIX, at the hour of the Buffalo</h6>
 326                         <a name=1235092615>
 327                         <h2>Code reviews</h2>
 328
 329                         <p>
 330                         </p><p>
 331                         It has been said that reviewing patches is a most thankless job.  As I really
 332                         like the elegance of Git's source code, and care a lot about it, I did not
 333                         think that it was thankless, just a little bit tedious (especially when the
 334                         patch authors mistake criticism for personal attacks).
 335                         </p><p>
 336                         Usually, I am pretty good at ignoring insults as responses to my comments;
 337                         after all, I have a lot more enjoyable things to do than to spend time talking
 338                         to a guy who shows how wise he is when he thinks that I criticize him
 339                         <u>personally</u> when I just try to enhance his work, by offering a little bit of
 340                         my knowledge.
 341                         </p><p>
 342                         However, in the last days, three people really seemed to want to insult me,
 343                         to make me go away, to stop the fun I have with Git.
 344                         </p><p>
 345                         And they almost succeeded.
 346                         </p><p>
 347                         So I guess it is time to reassess my priorities, and maybe stop reviewing
 348                         Git patches altogether.
 349                         </p>
 350                         <h6>Thursday, 12th of February, Anno Domini MMIX, at the hour of the Tiger</h6>
 351                         <a name=1234409395>
 352                         <h2>Interactive <i>rebase</i> just learnt a new command: <i>topic</i></h2>
 353
 354                         <p>
 355                         </p><p>
 356                         Today I am pretty pleased with myself.  Two projects at my day job got a real
 357                         boost, and I implemented a shortcut that avoids the ugly 'bookmark' statement
 358                         in rebase scripts most of the time.
 359                         </p><p>
 360                         A typical rebase script, generated by <i>git rebase -i -p $COMMIT</i> will look
 361                         something like this:
 362                         </p><p>
 363                         <table
 364                                                         border=1 bgcolor=black>
 365                                                 <tr><td bgcolor=lightblue colspan=3>
 366                                 <pre>                                                                                </pre>
 367                         </td></tr>
 368                         <tr><td>
 369                                 <table cellspacing=5 border=0
 370                                          style="color:white;">
 371                                 <tr><td>
 372                                         <pre>
 373 pick 1234567 My first commit
 374 topic begin super-cool-feature
 375 pick 2345678 The super cool feature
 376 pick 3456789 Documentation for the super cool feature
 377 topic end super-cool-feature
 378 </pre>
 379                                                         </td></tr>
 380                                                         </table>
 381                                                 </td></tr>
 382                                                 </table>
 383                         </p><p>
 384                         The result will be a merge commit at the HEAD whose first parent is
 385                         "My first commit", whose second parent is "Documentation for the super
 386                         cool feature" and whose commit message is "Merge branch 'super-cool-feature'".
 387                         </p><p>
 388                         Side note: internally, <i>topic begin $NAME [at $COMMIT]</i> will be handled as if
 389                         you wrote <i>bookmark merge-parent-of-$NAME; goto $COMMIT</i>, and
 390                         <i>topic end $NAME [$MESSAGE]</i> will be handled as if you wrote
 391                         <i>bookmark $NAME; goto merge-parent-of-$NAME; merge parents $NAME [original $MARK Merge branch '$NAME']</i>.
 392                         </p><p>
 393                         Of course, being more concise, the 'topic' statement is not only nicer to the
 394                         eye, but also less error-prone.
 395                         </p><p>
 396                         And hopefully many people will agree with me that this rebase script is pretty
 397                         intuitive.
 398                         </p>
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