Improve performance

[stuaxo]

Hi, Thanks for this, I couldn't quite get powerline itself to work in my setup so this is handy.

Where I work the git repo is really big so each git command takes about 0.3 seconds.

As there a few it takes about a second to draw for the prompt to draw.

I don't know git well enough to provide a patch, but I was looking at whether its possible to get more of the stats using fewer external commands,

As an experiment I've made a script that gets the changed file count, and the the amount of insertions, using one call to git diff --shortstat and then parsing the output in bash.

Maybe this would be useful in helping speed up rendering of the prompt?

$  ./parse_git_stats.sh

original output: " 3 files changed"
changed: '3'
inserted: '4'

script:

#!/bin/bash

# Set comma as the delimiter
IFS=','

read -a gitstat <<< $(git diff --shortstat)

# Example output from git diff --shortstat:
#  3 files changed, 4 insertions(+)
#
# read has split it by comma, next remove space prefix and text suffix
# using bash.

git_changed=${gitstat[0]%" files changed"}
git_changed=${git_changed# }

git_insertions=${gitstat[1]% "insertions(+)"}
git_insertions=${git_insertions# }

echo "changed: '"$git_changed"'"
echo "inserted: '"$git_insertions"'"

Most of the work is removing the prefixes + suffixes from the strings.

[stuaxo]

Hi, You can benchmark the segments by editing __powerline_prompt_command to output how long each one takes:

function __powerline_prompt_command {
  local last_status="$?" ## always the first
  local separator_char="${POWERLINE_PROMPT_CHAR}"

  LEFT_PROMPT=""
  SEGMENTS_AT_LEFT=0
  LAST_SEGMENT_COLOR=""

  TIMEFORMAT=%R
  ## left prompt ##
  for segment in $POWERLINE_PROMPT; do
    local f="__powerline_${segment}_prompt"
    #local info="$(__powerline_${segment}_prompt)"
    echo -ne "$segment: "
    time local info="$($f)"    
    [[ -n "${info}" ]] && __powerline_left_segment "${info}"
  done

  [[ -n "${LEFT_PROMPT}" ]] && LEFT_PROMPT+="$(__color - ${LAST_SEGMENT_COLOR})${separator_char}$(__color)"
  PS1="${LEFT_PROMPT} "

  ## cleanup ##
  unset LAST_SEGMENT_COLOR \
        LEFT_PROMPT \
        SEGMENTS_AT_LEFT
}

Then re-run .bashrc:

source ~/.bashrc

And get timing output:

/.bash/themes/git_bash_windows_powerline> > master>>
last_status: 0.389
user_info: 0.069
cwd: 0.069
scm: 2.744

There a few possible avenues for optimisation, but having timing information makes it much easier.

[stuaxo]

Based on this, I've made an easy performance fix for last_status.

https://github.com/diesire/git_bash_windows_powerline/pull/3