narrowbundle2: when we handle a widen, mark the operation as unsafe We have to manually drive the context manager here since the logic is awkwardly split between a couple of places. Differential Revision: https://phab.mercurial-scm.org/D3719

narrow: mark the critical chunks of narrowing/widening as unsafe I'm _mostly_ sure these are the only unsafe chunks here. Differential Revision: https://phab.mercurial-scm.org/D3718

repair: mark the critical section of strip() as unsafe When our experimental nointerrupt feature is enabled, this will help prevent users from corrupting their repo during a strip. Differential Revision: https://phab.mercurial-scm.org/D3717

ui: add an uninterruptable context manager that can block SIGINT The blocking of SIGINT is not done by default, but my hope is that we will one day. This was inspired by Facebook's "nointerrupt" extension, which is a bit more heavy-handed than this (whole commands are treated as unsafe to interrupt). A future patch will enable this for varying bits of Mercurial that are performing unsafe operations. It's intentional that the KeyboardInterrupt is raised as the context manager exits: during the span of the context manager interrupting Mercurial could lead to data loss, but typically those spans are fairly narrow, so we can let the unsafe block complete and then terminate hg (which will leave the repo in a consistent state, even if it's not the user's desired state). .. api:: New context manager ``ui.uninterruptable()`` to mark portions of a command as potentially unsafe places to interrupt Mercurial with Control-C or similar. Differential Revision: https://phab.mercurial-scm.org/D3716

merge with stable

revset: add partial support for ancestor(wdir()) It's easy, so let's make it happen. I'm not certain if 'wdir() &' should be required. ancestors(wdir()) works without it, but ancestor(wdir()) doesn't as of now. That's the issue of fullreposet.__contains__() vs __and__().

context: also accept diff option directly For now we accept both diff option and dictionary. This will let us upgrade internal users gradually before we drop the old API at the end of this series.

context: also take all other arguments than `patch.diff` accept This is needed to use `context.diff` as a full replacement of `patch.diff`

context: explicitly take diffopts in `context.diff` (API) To provide a proper replacement for the `patch.diff(…)` function, the `context.diff(…)` method needs to be able to take more parameters. To distinguish the diff options from the new other arguments, we upgrade the diff options to its own explicit argument.

rebase: check whether the rebasestate exists or not a bit early Converted the else part into `if True` because that part will soon be under a except part. Differential Revision: https://phab.mercurial-scm.org/D3876

rebase: use staeobj to check whether interrupted rebase exists This cleans up the code a bit. Differential Revision: https://phab.mercurial-scm.org/D3875

rebase: add a stateobj variable to rebaseruntime class The stateobj variable is an object of state.cmdstate() and will be used in upcoming patches to clean up the logic a bit and also use cbor format to write data to rebasestate class. Differential Revision: https://phab.mercurial-scm.org/D3874

rebase: refactor logic to read rebasestate in a separate function This will help us in plugging the use of state.cmdstate() to read rebasestate. Differential Revision: https://phab.mercurial-scm.org/D3873

revlog: reuse 'descendant' implemention in 'isancestor' The two functions do the same thing, but one takes nodes while the other takes revs. Using one to implement the other make sense. We should probably cleanup the API at some point to avoid having so many similar functions. However, we focus on an efficient implementation for now.

revlog: efficient implementation of 'descendant' Iterating over descendants is costly, because there are no "parent -> children" pointers. Walking the other way around is much more efficient, especially on large repositories, where descendant walks can cost seconds. And the other hand, common ancestors code follows links in the right direction and has a compiled implementation. In real life usage, this saved up to 80s during some pull operations, where descendant test happens in extension code.

revlog: refactor out the rev-oriented part of commonancestorheads We plan to use this in a function taking revs as argument. Round trips to nodes seem silly.