scmutil: add a cleanupnodes method for developers It's now common that an old node gets replaced by zero or more new nodes, that could happen with amend, rebase, histedit, etc. And it's a common requirement to do bookmark movements, strip or obsolete nodes and even moving working copy parent. Previously, amend, rebase, history have their own logic doing the above. This patch is an attempt to unify them and future code. This enables new developers to be able to do "replace X with Y" thing correctly, without any knowledge about bookmarks, strip or obsstore. The next step will be migrating rebase to the new API, so it works inside a transaction, and its code could be simplified.

strip: add a delayedstrip method that works in a transaction For long, the fact that strip does not work inside a transaction and some code has to work with both obsstore and fallback to strip lead to duplicated code like: with repo.transaction(): .... if obsstore: obsstore.createmarkers(...) if not obsstore: repair.strip(...) Things get more complex when you want to call something which may call strip under the hood. Like you cannot simply write: with repo.transaction(): .... rebasemod.rebase(...) # may call "strip", so this doesn't work But you do want rebase to run inside a same transaction if possible, so the code may look like: with repo.transaction(): .... if obsstore: rebasemod.rebase(...) obsstore.createmarkers(...) if not obsstore: rebasemod.rebase(...) repair.strip(...) That's ugly and error-prone. Ideally it's possible to just write: with repo.transaction(): rebasemod.rebase(...) saferemovenodes(...) This patch is the first step towards that. It adds a "delayedstrip" method to repair.py which maintains a postclose callback in the transaction object.

workingfilectx: add audit() as a wrapper for wvfs.audit()

workingfilectx: add backgroundclose as a kwarg to write() This is necessary because some callers in merge.py pass backgroundclose=True when writing. As with previous changes in this series, this should be a no-op.

merge: change repo.wvfs.setflags calls to a new wctx[f].setflags function As with previous changes in this series, this should be a no-op.

merge: convert repo.wwrite() calls to wctx[f].write() As with the previous patch in this series, workingfilectx.write() is a direct call to repo.wwrite(), so this change should be a no-op.

merge: replace repo.wvfs.unlinkpath() with calls to wctx[f].remove() The code inside workingfilectx.remove() is a straight call to repo.wvfs.unlinkpath, so this should be a no-op.

merge: pass wctx to batchremove and batchget We would like to migrate direct calls of repo.wvfs/wwrite/wread/etc to a call on the relevant workingfilectx, both as a cleanup (to reduce the number of working copy functions on `repo`), and also to facilitate an in-memory merge that doesn't write to the working copy. In order to do that, the first step is to ensure we pass the target wctx around and perform our writes and reads on it. Later, this object might become a memctx.

revset: add depth limit to descendants() (issue5374) This is naive implementation using two-pass scanning. Tracking descendants isn't an easy problem if both start and stop depths are specified. It's impractical to remember all possible depths of each node while scanning from roots to descendants because the number of depths explodes. Instead, we could cache (min, max) depths as a good approximation and track ancestors back when needed, but that's likely to have off-by-one bug. Since this implementation appears not significantly slower, and is quite straightforward, I think it's good enough for practical use cases. The time and space complexity is O(n) ish. revisions: 0) 1-pass scanning with (min, max)-depth cache (worst-case quadratic) 1) 2-pass scanning (this version) repository: mozilla-central # descendants(0) (for reference) *) 0.430353 # descendants(0, depth=1000) 0) 0.264889 1) 0.398289 # descendants(limit(tip:0, 1, offset=10000), depth=1000) 0) 0.025478 1) 0.029099 # descendants(0, depth=2000, startdepth=1000) 0) painfully slow (due to quadratic backtracking of ancestors) 1) 1.531138

dagop: make walk direction switchable so it can track descendants # ancestors(tip) using hg repo 2) 0.068527 3) 0.069097

dagop: factor out generator of ancestor nodes # ancestors(tip) using hg repo 1) 0.068976 2) 0.068527

dagop: factor out pfunc from revancestors() generator This generator will be reused for tracking descendants with depth limit. # ancestors(tip) using hg repo 0) 0.065868 1) 0.068976