GSOC, Git Blog 10

Week10 New Start

Bug Solving

The first thing is the two bugs mentioned last week now have their solutions.

I asked ikke for help on IRC and learned where the bug was introduced: c49a177be (test-lib.sh: set COLUMNS=80 for —verbose repeatability), and then Atharva told me that there seems to be a thread on the mailing list discussing this bug: progress test failure on fedora34. The conclusion is that when using checkwinsize option (default), bash will check and update the window size (by setting LINES and COLUMNS) after each external command. This causes the COLUMENS=80 setting in the patch to become invalid.

The current solution is using shopt -u checkwinsize to disable this option.

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 9e26860544..ebcd3b0bab 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -407,6 +407,7 @@ LC_ALL=C
 PAGER=cat
 TZ=UTC
 COLUMNS=80
+shopt -u checkwinsize
 export LANG LC_ALL PAGER TZ COLUMNS
 EDITOR=:

This bug has troubled me for a long time, thanks to the people mentioned above who helped me.

GIT_CHERRY_PICK_HELP="Something" git cherry-pick <commit>... Junio believes that environment variable GIT_CHERRY_PICK_HELP is the implementation detail of rebase (or other sub-commands), so the correct solution to this bug is unsetenv("GIT_CHERRY_PICK_HELP") In cmd_cherry_pick(). In this way, git cherry-pick will ignore GIT_CHERRY_PICK_HELP. However, some functions of such a commonly used sub-command git cherry-pick have not been perfected, which was endorsed by Felipe. Maybe I can do my best to make some optimizations later…

Project Progress

At Christian’s suggestion, I split my patch series into two parts, the first part is to add two atoms %(rest) and %(raw) to the ref-filter; the second part is to let cat-file —batch reuse the logic of ref-filter. Currently I only submit the first part to the mailing list. This may arouse the enthusiasm of reviewers to review my patch :). Ævar, Junio and Jacob gave me some suggestions about some code and commit message’s details. Now the patch is here: [PATCH v2 0/5] [GSOC] ref-filter: add %(raw) and %(rest) atoms. On the other hand, we started a new discussion on the performance of git cat-file —batch… [GSOC] How to improve the performance of git cat-file —batch

第 10 周新的开始

解决 Bug

首先要说的是，上周提到的两个 bug 现在都有了解决方案。

我在 IRC 上向 ikke 求助，了解到这个 bug 是在 c49a177be（test-lib.sh: set COLUMNS=80 for —verbose repeatability）中引入的；然后 Atharva 告诉我邮件列表上似乎有一个讨论这个 bug 的帖子：progress test failure on fedora34。结论是，当使用 checkwinsize 选项（默认开启）时，bash 会在每次外部命令执行后检查并更新窗口大小（通过设置 LINES 和 COLUMNS）。这导致补丁中 COLUMNS=80 的设置失效。

目前的解决方案是使用 shopt -u checkwinsize 禁用该选项。

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 9e26860544..ebcd3b0bab 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -407,6 +407,7 @@ LC_ALL=C
 PAGER=cat
 TZ=UTC
 COLUMNS=80
+shopt -u checkwinsize
 export LANG LC_ALL PAGER TZ COLUMNS
 EDITOR=:

这个 bug 困扰了我很久，感谢上面提到的人对我的帮助。

GIT_CHERRY_PICK_HELP="Something" git cherry-pick <commit>... Junio 认为环境变量 GIT_CHERRY_PICK_HELP 是 rebase（或其他子命令）的实现细节，因此这个 bug 的正确解决方案是在 cmd_cherry_pick() 中调用 unsetenv("GIT_CHERRY_PICK_HELP")。这样 git cherry-pick 就会忽略 GIT_CHERRY_PICK_HELP。然而，像 git cherry-pick 这样常用的子命令还有一些功能尚未完善，Felipe 也认同这一点。也许之后我可以尽力做一些优化……

项目进展