Where did Documentation/perf_counter disappear from linux-2.6-tip.git ?

Dnia 22 grudnia 2009 11:04 Tomas Carnecky<[email protected]> napisał(a):

Quoted 34 lines

   $ git --version
git version 1.6.6.rc4

# Documentation/perf_counter is missing from the master branch, so first let's find

# out what the last commit was that touched that subdirectory:
$ git log --all -1 -- Documentation/perf_counter
commit 436224a6d8bb3e29fe0cc18122f8d1f593da67b8
Author: Peter Zijlstra<[email protected]>
Date:   Tue Jun 2 21:02:36 2009 +0200
...
M       Documentation/perf_counter/builtin-report.c

# Great, let's look in which branch that commit is

$ git branch --contains 436224a6d8bb3e29fe0cc18122f8d1f593da67b8
* master

# So, let's look at the log of master and limit it to that subdirectory:

$ git log master -- Documentation/perf_counter
$

# Damn, that doesn't make any sense. In commit 43622 there were files in that subdirectory, in master they have gone missing and yet log doesn't show any commit touching that subdirectory?
# Let's try something different:

$ git log --diff-filter=D --name-status --all -- Documentation/perf_counter
...

# Ah, now we're getting somewhere, but still no sight of a commit which removed for example Documentation/perf_counter/.gitignore
# I'm sure I'm probably just missing a tiny little switch for git-log. I also tried other combination of name-status, diff-filter etc, but soon after gave up.

Quoted 2 lines

tom
--

Try

$ git log --follow -- Documentation/perf_counter

 $ git --version
git version 1.6.6.rc4

# Documentation/perf_counter is missing from the master branch, so first let's find

# out what the last commit was that touched that subdirectory:
$ git log --all -1 -- Documentation/perf_counter
commit 436224a6d8bb3e29fe0cc18122f8d1f593da67b8
Author: Peter Zijlstra <[email protected]>
Date:   Tue Jun 2 21:02:36 2009 +0200
...
M       Documentation/perf_counter/builtin-report.c

# Great, let's look in which branch that commit is

$ git branch --contains 436224a6d8bb3e29fe0cc18122f8d1f593da67b8
* master

# So, let's look at the log of master and limit it to that subdirectory:

$ git log master -- Documentation/perf_counter
$

Quoted 13 lines · Tomas Carnecky

  $ git --version
git version 1.6.6.rc4

# Documentation/perf_counter is missing from the master branch, so first let's find

# out what the last commit was that touched that subdirectory:
$ git log --all -1 -- Documentation/perf_counter
commit 436224a6d8bb3e29fe0cc18122f8d1f593da67b8
Author: Peter Zijlstra<[email protected]>
Date:   Tue Jun 2 21:02:36 2009 +0200
...
M       Documentation/perf_counter/builtin-report.c

Quoted 7 lines

# Great, let's look in which branch that commit is

$ git branch --contains 436224a6d8bb3e29fe0cc18122f8d1f593da67b8
* master

# So, let's look at the log of master and limit it to that subdirectory:

$ git log master -- Documentation/perf_counter
$

Add --full-history so that you would get _all_ possible explanation of the history, perhaps?

In a history with this shape:

     ---A---B---C---D---E
             \     /
              F---G

suppose that

- commit F introduces a path;
- commit G removes the path;
- no other commit has the path in question.

Without --full-history, "log E -- path" is asked to give "_one_ possible way to explain the current state of path in E" (iow, "why there is nothing there right now at E?").

Two explanations are possible even in this vastly simplified toy history.

- It didn't exist in A, and none of the subsequent commits B, C, D that lead to E did anything to change that.

- F added it, but G changed mind and removed it.

When "log" encounters a merge commit while traversing the history backwards (in this case D) with paths limiter, if there is a commit among its parent whose tree matches its tree with respect to the paths, side branches leading to all the other parents are culled and only that one history is followed to explain the history. In this case, neither C or D has the path, so their trees with respect to the paths limiter match, and git doesn't follow the side branch that has F and G without --full-history.