ii. For each source in the best order, do the following merge:
(Our base has sources:
- the branch for each direct dep
- - the remote base)
+ - the remote base
+ - the topgit base, if this is a topgit import)
Find the (latest) common ancestor.
- Check for unwanted dependency removals.
+ Check for unwanted dependency removals.
An unwanted dependency removal is
A branch in the desired included deps
Which exists in the common ancestor's actual included deps
For each unwanted dependency removal (ie for each such
branch), search as follows:
* An "unwanted removal commit" is a non-merge commit in the
- history of the source, which unwantedly removes the dep
- from the actual included deps.
+ history of the source, which removes the dep from the
+ actual included deps.
* But the search stops at any point where we would have to
traverse a commit where .topbloke/deps is empty (which
stops us looking into the hitory of non-topbloke-controlled
branches). This can be done with git-rev-list
--remove-empty.
+ * It also stops at any point where we meet a commit which
+ does have the dep in the actual included deps. We have
+ to do this by hand.
* The the relevant unwanted removal commit for that dep is
the most recent unwanted removal commit, as defined.
Select the unwantedly removed dep whose relevant unwanted
from the source.
iii.
+ Check whether our list of dependencies has changed. If so
+ we need to restart the whole base update.
+
+ iv.
Check for missing or unwanted dependency inclusions. Compare
our base's desired included deps with our base's actual
included deps. In exceptional conditions, they will not
* Attempt to apply the appropriate diff to add (resp. remove)
the contents of the relevant patch (adjusted appropriately
for metadata, XXX??? particularly the actual inclusion list)
+ XXX if we want to add a dep we need to update the dep first
* Go round again looking for another discrepancy.
3. Update our branch.
Our branch has sources:
- our base
- the remote for our branch
+ - the topgit branch, if this is a topgit import
For each source in the best order, do the merge.
Double-check the actual dependency inclusions. In
The "best order" for merges is in order of recency of common
ancestor, most recent first, and if that does not distinguish,
merging from local branches first.
-
-"Recency" refers to the order from git-rev-list --date-order.
-
-Actual included deps:
-
- This is tracked explicitly in .topbloke/included, one branch per
- line. For compatibility with older versions, every time we think
- about a base, branch or source above, we check whether
- .topbloke/included is present.
-
- If it isn't then we calculate a child commit which has a
- .topbloke/included. In the case of a remote branch or base, we
- substitute this child commit for the relevant remote ref but do
- not record it in the remote ref; in the case of a local branch or
- base, we advance the local branch or base accordingly.
- When .topbloke/included is calculated in this way, it always gets
- the list of desired included deps. (topgit,
- which does not support dependency deletion, always has exactly the
- desired deps actually included.)
-
- Foreign branches cannot be removed from included and cannot
- therefore be removed from dependency lists.
+"Recency" refers to the order from git-rev-list --date-order.
Patch removal:
Operations like "go up the stack", goes towards leaf. Hopefully unique.
"Down" the stack, uses a "conventional" linearisation
Stack reordering op ? auto adjust deps
+
+
+When merging, we need to DTRT with our metadata.
+Do this by running write-tree/read-tree etc. ourselves ?
+For a source we're merging from, we make a version where the
+metadata we shouldn't be merging is removed ?
+Or something.
+Have discovered that specifying a custom merge driver for a file does
+not have any effect if the three-way-merge looks trivial based
+on looking at the file contents - at least, if you use git-merge.
+
+Only thing which knows how to do all the gitattributes stuff and
+conflict markers and what have you is git-merge. (git-merge-tree does
+too but the output format is unsuitable.) "git-merge-index
+... git-merge-one-file" does not honour the merge drivers and is,
+contrary to what the git docs seem to suggest but don't actually
+state, not actualy used by git-merge.
+
+OK so here is a plan:
+ Use git-merge --no-commit
+ Perhaps on a HEAD, and/or against a tree, which have been massaged
+ to make the metadata suitable as input.
+ Filtering out the "merge was successful but we aren't committing"
+ message. Use a single pipe for stdout/stderr to get interleaving
+ right; the message from git-merge is not i18n'd.
+ Afterwards we:
+ Check for merge success in the index and compare to exit status
+ from git-merge (which is 1 if the merge failed).
+ Adjust the metadata.
+ Print appropriate big fat warnings if we have merge conflicts in our
+ metadata.
+ Commit, adjusting the parents of the new commit to the original
+ parents if we made the merge with special massaged parents.
+ We may still need to have custom merge drivers for metadata.
+
+
+Strategies for each metadata file merge:
+
+ in base/tip same patch & branch dep -> base base -> tip
+
+ msg T textual merge rm from src not in src
+ deps B list merge rm from src rm from src
+ deleted T std existence merge rm from src not in src
+ patch- BT must be same rm from src must be same
+ topgit- B std exist/text merge rm from src rm from src
+ [^+]*- ?? textual merge rm from src rm from src
+ +included BT list merge rm from non-tb src list merge
+ +*- ?? textual merge rm from non-tb src textual merge
+ *[^-] ?? die, aborting all ops, if found in any tb src or branch
+
+
+
+
+
+Unwanted removal search subgraphs:
+
+ rm relevant removal
+ inc
+
+ rm impossible to undo removal, arrgh, terminates search
+inc inc..
+/ ??? \
+
+ rm
+inc.. rm.. merge of a removal, search down the rm path
+/ [inc] \
+
+ inc ??? call it an inclusion, terminate the search
+ rm
+
+ inc merge of an inclusion, terminates search
+inc.. rm..
+/ [rm] \
+
+ inc ??? call it an inclusion, terminate search
+rm.. rm..
+/ ??? \
+
+
+ rm inc inc rm irrelevant
+ rm inc inc inc.. rm rm..
+
+
+
+ OUR BASE SOURCE OUR IT TIP
+ | | |
+ | | |
+ ADD DEP WH/ inc rm |
+ NEEDS IT /| /\ |
+ / | rm \ |
+ / | ______________'/ \ |
+ inc |' / \ | IT tip
+ / inc REMOVAL rm \ | elsewhere
+ / | / \ | | |
+ / | inc \ | | |
+ some IT | / | | | |
+ | inc | | | |
+ / | | | | |
+ / inc | | | |
+ | / | | | | |
+ / / inc | | | |
+ / | | `------------ | ----<-------- | -.| |
+ / inc inc | | *2 |
+ | |`- | ------------- | ----<--------.| | |
+ | `---inc | 1* / |
+ | | | | / |
+ | RE-INCLUDE inc rm REMOVAL |' |
+ inc \ | | | |
+ | * REMOVAL rm | | |
+ | | / | |
+ |`-------------- | ----------. / | |
+ | | inc ANC2 | |
+ inc inc / | |
+ |`.____________ | / | |
+ | `inc ANC1 / | |
+ | | /`--------<----------- | ---. |
+ without inc / | \/
+ | | / | /
+ \ RE-INCLUDE inc / | /
+ \ \ | / | /
+ \ * REMOVAL rm / | /
+ \ | / | /
+ \ inc FIRST ADD DEP |/
+ \ | \ *3
+ \ | `------------<-------------.|
+ \ | |
+ \ without |
+ \_____ | |
+ `without |
+ | |
+ IT
+
+
+ Merge 1* and 2*, diff against some relevant base branch commit
+ or something, and apply to proposed. ???
+
+
+After we are done:
+ source tip is included in our base
+
+Each time:
+ * pick common ancestor
+ * compute whether merge from common anc would unwantedly remove
+ * if so we arrange that the common anc is a "rm" but our branch
+ actually contains IT
~ian / topbloke.git / blobdiff