obsutil: move 'successorssets' to the new modules We have a new 'obsutil' module now. We move this high level utility there to bring 'obsolete.py' back to a more reasonable size.

revlog: add an experimental option to mitigated delta issues (issue5480) The general delta heuristic to select a delta do not scale with the number of branch. The delta base is frequently too far away to be able to reuse a chain according to the "distance" criteria. This leads to insertion of larger delta (or even full text) that themselves push the bases for the next delta further away leading to more large deltas and full texts. This full text and frequent recomputation throw Mercurial performance in disarray. For example of a slightly large repository 280 000 files (2 150 000 versions) 430 000 changesets (10 000 topological heads) Number below compares repository with and without the distance criteria: manifest size: with: 21.4 GB without: 0.3 GB store size: with: 28.7 GB without 7.4 GB bundle last 15 00 revisions: with: 800 seconds 971 MB without: 50 seconds 73 MB unbundle time (of the last 15K revisions): with: 1150 seconds (~19 minutes) without: 35 seconds Similar issues has been observed in other repositories. Adding a new option or "feature" on stable is uncommon. However, given that this issues is making Mercurial practically unusable, I'm exceptionally targeting this patch for stable. What is actually needed is a full rework of the delta building and reading logic. However, that will be a longer process and churn not suitable for stable. In the meantime, we introduces a quick and dirty mitigation of this in the 'experimental' config space. The new option introduces a way to set the maximum amount of memory usable to store a diff in memory. This extend the ability for Mercurial to create chains without removing all safe guard regarding memory access. The option should be phased out when core has a more proper solution available. Setting the limit to '0' remove all limits, setting it to '-1' use the default limit (textsize x 4).

tests: fix variable name regular expression in _genrestoreenv() Update the code to correctly anchor the expression on the end of the name, to require that the entire name match this expression. It was already anchored at the start by using re.match(), but this does not anchor it at the end.

merge with stable

pushrace: avoid crash on bare push when using concurrent push mode If the remote is empty, we do now bother computing head changes and the 'pushbranchmap' attribute stays at None. We now handle and tests this case.

show: config option to register aliases for views As part of using `hg show` in my daily workflow, I've found it slightly annoying to have to type full view names, complete with a space. I've locally registered an alias for "swork = show work." I think others will have this same complaint and could benefit from some automation to streamline the creation of aliases. So, this commit introduces a config option that allows `hg show` views to be automatically aliased using a given prefix. e.g. a value of "s" will automatically register "swork" and "sbookmarks." Multiple values can be given for ultimate flexibility. This arguably isn't needed now. But since we don't register aliases if there will be a collision and we're bound to have a collision, it makes sense to allow multiple prefixes so specific views can avoid collisions by using different prefixes.

blackbox: use a human readable version of the default Now that the default value is also converted we can use a human readable version for it. This will be useful if we start to automatically display the default config value in various place.

configitems: register 'blackbox.maxsize' as an example of 'configbytes' This exercise the default value handling in 'configbytes'.

blackbox: minor code reordering The version declaration should come first in my opinion. This will help gather the command table with the config table.

configitems: add a devel warning for extensions items overiding core one We do not want such case to pass silently. In the future we'll likely have useful tool for an extension to alter the existing definition in core.