Selective compressed git branch topology

git2dot.bash

#!/usr/bin/env bash
# vim:filetype=sh:tabstop=4:shiftwidth=4:expandtab:

set -e

typeset -A streams # associative array / map
relevant_commits=()

get_stream() {
    local input=$1
    local interim_stream_name=${input//\//_}
    local final_stream_name=${interim_stream_name//\-/_}
    echo ${final_stream_name}
}

compare_commits() {
    update_relevant_commits $1
    update_relevant_commits $2

    if [ "$1" != "$2" ]; then
        local merge_base=$(git rev-parse --short $(git merge-base $1 $2))
        update_relevant_commits ${merge_base}
    fi
}

update_relevant_commits() {
    if [[ ${relevant_commits[@]} != *"$1"* ]]; then
        relevant_commits=($1 ${relevant_commits[@]})
        new_compare_set+=($1)
        for s in ${!streams[@]}; do
            if [[ ${streams[${s}]} != *"$1"* ]]; then
                local sv=(${streams[${s}]})
                local b=${sv[-1]}
                if git branch --contains $1 | grep ${b} > /dev/null 2>&1; then
                    streams[${s}]="$1 ${sv[@]}"
                fi
            fi
        done
    fi
}

compare_set=()

for b in $(git branch --format='%(refname:short)'); do
    tip=$(git show-ref --hash --abbrev refs/heads/${b})
    s=$(get_stream ${b})
    streams[${s}]="${tip} ${b}"
    compare_set+=(${tip})
done

while [ ${#compare_set[@]} -gt 1 ]; do
    new_compare_set=()
    for i in ${compare_set[@]}; do
        for j in ${compare_set[@]}; do
            compare_commits ${i} ${j}
        done
    done
    compare_set=(${new_compare_set[@]})
done

echo 'strict digraph {' > /tmp/generated.dot
for s in ${!streams[@]}; do
    echo "node[group=\"${s}\"]" >> /tmp/generated.dot
    commits_in_stream=${streams[${s}]}
    echo ${commits_in_stream} | sed -e 's/^/"/' -e 's/ /" -> "/g' -e 's/$/"/' >> /tmp/generated.dot
done
echo '}' >> /tmp/generated.dot

1. Install graphviz
2. Clone git repo fresh
3. Checkout only branches you need to view topology for
4. Run the above script
5. Run command dot -Tsvg /tmp/generated.dot -o /tmp/generated.svg