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__git_ps1() is usually added to the prompt inside a command
substitution, imposing the overhead of fork()ing a subshell. Using
__git_ps1() for $PROMPT_COMMAND is slightly faster, because it avoids
that command substitution.
Mention this in the comments about setting up the git prompt.
The whole series speeds up the bash prompt on Windows/MSysGit
considerably. Here are some timing results in three scenarios, each
repeated 10 times:
At the top of the work tree, before:
$ time for i in {0..9} ; do prompt="$(__git_ps1)" ; done
real 0m1.716s
user 0m0.301s
sys 0m0.772s
After:
real 0m0.687s
user 0m0.075s
sys 0m0.396s
After, from $PROMPT_COMMAND:
$ time for i in {0..9} ; do __git_ps1 '\h:\w' '$ ' ; done
real 0m0.546s
user 0m0.075s
sys 0m0.181s
At the top of the work tree, detached head, before:
real 0m2.574s
user 0m0.376s
sys 0m1.207s
After:
real 0m1.139s
user 0m0.151s
sys 0m0.500s
After, from $PROMPT_COMMAND:
real 0m1.030s
user 0m0.245s
sys 0m0.336s
In a subdirectory, during rebase, stash status indicator enabled,
before:
real 0m3.557s
user 0m0.495s
sys 0m1.767s
After:
real 0m0.717s
user 0m0.120s
sys 0m0.300s
After, from $PROMPT_COMMAND:
real 0m0.577s
user 0m0.047s
sys 0m0.258s
On Linux the speedup ratio is comparable to Windows, but overall it
was about an order of magnitude faster to begin with. The last case
from above, repeated 100 times, before:
$ time for i in {0..99} ; do prompt="$(__git_ps1)" ; done
real 0m2.806s
user 0m0.180s
sys 0m0.264s
After:
real 0m0.857s
user 0m0.020s
sys 0m0.028s
Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>
Contributed Software Although these pieces are available as part of the official git source tree, they are in somewhat different status. The intention is to keep interesting tools around git here, maybe even experimental ones, to give users an easier access to them, and to give tools wider exposure, so that they can be improved faster. I am not expecting to touch these myself that much. As far as my day-to-day operation is concerned, these subdirectories are owned by their respective primary authors. I am willing to help if users of these components and the contrib/ subtree "owners" have technical/design issues to resolve, but the initiative to fix and/or enhance things _must_ be on the side of the subtree owners. IOW, I won't be actively looking for bugs and rooms for enhancements in them as the git maintainer -- I may only do so just as one of the users when I want to scratch my own itch. If you have patches to things in contrib/ area, the patch should be first sent to the primary author, and then the primary author should ack and forward it to me (git pull request is nicer). This is the same way as how I have been treating gitk, and to a lesser degree various foreign SCM interfaces, so you know the drill. I expect that things that start their life in the contrib/ area to graduate out of contrib/ once they mature, either by becoming projects on their own, or moving to the toplevel directory. On the other hand, I expect I'll be proposing removal of disused and inactive ones from time to time. If you have new things to add to this area, please first propose it on the git mailing list, and after a list discussion proves there are some general interests (it does not have to be a list-wide consensus for a tool targeted to a relatively narrow audience -- for example I do not work with projects whose upstream is svn, so I have no use for git-svn myself, but it is of general interest for people who need to interoperate with SVN repositories in a way git-svn works better than git-svnimport), submit a patch to create a subdirectory of contrib/ and put your stuff there. -jc