Restoring a database, including all its children

Question

I have the following Git repository topology:

ABF (master) \ D (feature-a) \ / C (feature) \ E (feature-b) 

By canceling the feature branch, I expected to reinstall the entire subtree (including child branches):

 $ git rebase feature master ABF (master) \ D (feature-a) \ / C (feature) \ E (feature-b) 

However, this is the actual result:

  C' (feature) / ABF (master) \ D (feature-a) \ / C \ E (feature-b) 

I know that I can easily fix it manually by doing:

 $ git rebase --onto feature C feature-a $ git rebase --onto feature C feature-b 

But is there a way to automatically reinstall a branch, including all its children / children?

Answer 1

 git branch --contains C | \ xargs -n 1 \ git rebase --committer-date-is-author-date --preserve-merges --onto BC^ 

Answer 2

A few years ago, I wrote something to deal with such things. (Comments for improvement are welcome, of course, but don't judge too much - that was a long time ago! I didn't even know Perl!)

This meant for more static situations - you configure it by setting the configuration parameters for the form branch.<branch>.autorebaseparent . It will not touch any branches that do not have this set of configuration parameters. If this is not what you want, you could probably hack it where you want, without much trouble. I have not used it very much in the last year or two, but when I used it, it always seemed quite safe and stable, as much as possible with a massive automatic reboot.

So there it is. Use it by saving it in a file called git-auto-rebase in PATH . It's probably also a good idea to use the dry run ( -n ) option before you really try it. It may be a little more detail than you really want, but it will show you what it is going to try and what. Could save you from sorrow.

 #!/bin/bash CACHE_DIR=.git/auto-rebase TODO=$CACHE_DIR/todo TODO_BACKUP=$CACHE_DIR/todo.backup COMPLETED=$CACHE_DIR/completed ORIGINAL_BRANCH=$CACHE_DIR/original_branch REF_NAMESPACE=refs/pre-auto-rebase print_help() { echo "Usage: git auto-rebase [opts]" echo "Options:" echo " -n dry run" echo " -c continue previous auto-rebase" echo " -a abort previous auto-rebase" echo " (leaves completed rebases intact)" } cleanup_autorebase() { rm -rf $CACHE_DIR if [ -n "$dry_run" ]; then # The dry run should do nothing here. It doesn't create refs, and won't # run unless auto-rebase is empty. Leave this here to catch programming # errors, and for possible future -f option. git for-each-ref --format="%(refname)" $REF_NAMESPACE | while read ref; do echo git update-ref -d $ref done else git for-each-ref --format="%(refname)" $REF_NAMESPACE | while read ref; do git update-ref -d $ref done fi } # Get the rebase relationships from branch.*.autorebaseparent get_config_relationships() { mkdir -p .git/auto-rebase # We cannot simply read the indicated parents and blindly follow their # instructions; they must form a directed acyclic graph (like git!) which # furthermore has no sources with two sinks (ie a branch may not be # rebased onto two others). # # The awk script checks for cycles and double-parents, then sorts first by # depth of hierarchy (how many parents it takes to get to a top-level # parent), then by parent name. This means that all rebasing onto a given # parent happens in a row - convenient for removal of cached refs. IFS=$'\n' git config --get-regexp 'branch\..+\.autorebaseparent' | \ awk '{ child=$1 sub("^branch[.]","",child) sub("[.]autorebaseparent$","",child) if (parent[child] != 0) { print "Error: branch "child" has more than one parent specified." error=1 exit 1 } parent[child]=$2 } END { if ( error != 0 ) exit error # check for cycles for (child in parent) { delete cache depth=0 cache[child]=1 cur=child while ( parent[cur] != 0 ) { depth++ cur=parent[cur] if ( cache[cur] != 0 ) { print "Error: cycle in branch."child".autorebaseparent hierarchy detected" exit 1 } else { cache[cur]=1 } } depths[child]=depth" "parent[child]" "child } n=asort(depths, children) for (i=1; i<=n; i++) { sub(".* ","",children[i]) } for (i=1; i<=n; i++) { if (parent[children[i]] != 0) print parent[children[i]],children[i] } }' > $TODO # Check for any errors. If the awk script good, this should really check # exit codes. if grep -q '^Error:' $TODO; then cat $TODO rm -rf $CACHE_DIR exit 1 fi cp $TODO $TODO_BACKUP } # Get relationships from config, or if continuing, verify validity of cache get_relationships() { if [ -n "$continue" ]; then if [ ! -d $CACHE_DIR ]; then echo "Error: You requested to continue a previous auto-rebase, but" echo "$CACHE_DIR does not exist." exit 1 fi if [ -f $TODO -a -f $TODO_BACKUP -a -f $ORIGINAL_BRANCH ]; then if ! cat $COMPLETED $TODO | diff - $TODO_BACKUP; then echo "Error: You requested to continue a previous auto-rebase, but the cache appears" echo "to be invalid (completed rebases + todo rebases != planned rebases)." echo "You may attempt to manually continue from what is stored in $CACHE_DIR" echo "or remove it with \"git auto-rebase -a\"" exit 1 fi else echo "Error: You requested to continue a previous auto-rebase, but some cached files" echo "are missing." echo "You may attempt to manually continue from what is stored in $CACHE_DIR" echo "or remove it with \"git auto-rebase -a\"" exit 1 fi elif [ -d $CACHE_DIR ]; then echo "A previous auto-rebase appears to have been left unfinished." echo "Either continue it with \"git auto-rebase -c\" or remove the cache with" echo "\"git auto-rebase -a\"" exit 1 else get_config_relationships fi } # Verify that desired branches exist, and pre-refs do not. check_ref_existence() { local parent child for pair in "${pairs[@]}"; do parent="${pair% *}" if ! git show-ref -q --verify "refs/heads/$parent" > /dev/null ; then if ! git show-ref -q --verify "refs/remotes/$parent" > /dev/null; then child="${pair#* }" echo "Error: specified parent branch $parent of branch $child does not exist" exit 1 fi fi if [ -z "$continue" ]; then if git show-ref -q --verify "$REF_NAMESPACE/$parent" > /dev/null; then echo "Error: ref $REF_NAMESPACE/$parent already exists" echo "Most likely a previous git-auto-rebase did not complete; if you have fixed all" echo "necessary rebases, you may try again after removing it with:" echo echo "git update-ref -d $REF_NAMESPACE/$parent" echo exit 1 fi else if ! git show-ref -q --verify "$REF_NAMESPACE/$parent" > /dev/null; then echo "Error: You requested to continue a previous auto-rebase, but the required" echo "cached ref $REF_NAMESPACE/$parent is missing." echo "You may attempt to manually continue from the contents of $CACHE_DIR" echo "and whatever refs in refs/$REF_NAMESPACE still exist, or abort the previous" echo "auto-rebase with \"git auto-rebase -a\"" exit 1 fi fi done } # Create the pre-refs, storing original position of rebased parents create_pre_refs() { local parent prev_parent for pair in "${pairs[@]}"; do parent="${pair% *}" if [ "$prev_parent" != "$parent" ]; then if [ -n "$dry_run" ]; then echo git update-ref "$REF_NAMESPACE/$parent" "$parent" \"\" else if ! git update-ref "$REF_NAMESPACE/$parent" "$parent" ""; then echo "Error: cannot create ref $REF_NAMESPACE/$parent" exit 1 fi fi fi prev_parent="$parent" done } # Perform the rebases, updating todo/completed as we go perform_rebases() { local prev_parent parent child for pair in "${pairs[@]}"; do parent="${pair% *}" child="${pair#* }" # We do this *before* rebasing, assuming most likely any failures will be # fixed with rebase --continue, and therefore should not be attempted again head -n 1 $TODO >> $COMPLETED sed -i '1d' $TODO if [ -n "$dry_run" ]; then echo git rebase --onto "$parent" "$REF_NAMESPACE/$parent" "$child" echo "Successfully rebased $child onto $parent" else echo git rebase --onto "$parent" "$REF_NAMESPACE/$parent" "$child" if ( git merge-ff -q "$child" "$parent" 2> /dev/null && echo "Fast-forwarded $child to $parent." ) || \ git rebase --onto "$parent" "$REF_NAMESPACE/$parent" "$child"; then echo "Successfully rebased $child onto $parent" else echo "Error rebasing $child onto $parent." echo 'You should either fix it (end with git rebase --continue) or abort it, then use' echo '"git auto-rebase -c" to continue. You may also use "git auto-rebase -a" to' echo 'abort the auto-rebase. Note that this will not undo already-completed rebases.' exit 1 fi fi prev_parent="$parent" done } rebase_all_intelligent() { if ! git rev-parse --show-git-dir &> /dev/null; then echo "Error: git-auto-rebase must be run from inside a git repository" exit 1 fi SUBDIRECTORY_OK=1 . "$(git --exec-path | sed 's/:/\n/' | grep -m 1 git-core)"/git-sh-setup cd_to_toplevel # Figure out what we need to do (continue, or read from config) get_relationships # Read the resulting todo list OLDIFS="$IFS" IFS=$'\n' pairs=($(cat $TODO)) IFS="$OLDIFS" # Store the original branch if [ -z "$continue" ]; then git symbolic-ref HEAD | sed 's@refs/heads/@@' > $ORIGINAL_BRANCH fi check_ref_existence # These three depend on the pairs array if [ -z "$continue" ]; then create_pre_refs fi perform_rebases echo "Returning to original branch" if [ -n "$dry_run" ]; then echo git checkout $(cat $ORIGINAL_BRANCH) else git checkout $(cat $ORIGINAL_BRANCH) > /dev/null fi if diff -q $COMPLETED $TODO_BACKUP ; then if [ "$(wc -l $TODO | cut -d" " -f1)" -eq 0 ]; then cleanup_autorebase echo "Auto-rebase complete" else echo "Error: todo-rebases not empty, but completed and planned rebases match." echo "This should not be possible, unless you hand-edited a cached file." echo "Examine $TODO, $TODO_BACKUP, and $COMPLETED to determine what went wrong." exit 1 fi else echo "Error: completed rebases don't match planned rebases." echo "Examine $TODO_BACKUP and $COMPLETED to determine what went wrong." exit 1 fi } while getopts "nca" opt; do case $opt in n ) dry_run=1;; c ) continue=1;; a ) abort=1;; * ) echo "git-auto-rebase is too dangerous to run with invalid options; exiting" print_help exit 1 esac done shift $((OPTIND-1)) case $# in 0 ) if [ -n "$abort" ]; then cleanup_autorebase else rebase_all_intelligent fi ;; * ) print_help exit 1 ;; esac 

One thing that I found, since I initially turned to this, is that sometimes the answer is that you really don't want to reinstall at all! There, something needs to be said to start the topic branches in the correct common ancestor in the first place and not try to push them forward after that. But this is between you and your workflow.