rhg: fix race when a fixup file is deleted on disk See next changeset for the other race in the same kind of logic and why there are two different places.

dirstate: test a `hg status` raced by a `hg remove` This shows that `rhg` is misbehaving here.

dirstate: tests racing status with both dirstate-v2 append and rewrite The way the racing process touches the dirstate results in different challenges for the raced process. We now test each variant in the `test-dirstate-status-race.t` tests.

dirstate-v2: add devel config option to control write behavior This will help us to write predictable tests checking behavior in each case.

dirstate: use more than a bool to control append behavior When writing dirstate-v2, we might either append to the existing file, or create a new file. We are about to introduce some configuration to control this behavior. As a prelude, we change the current way the behavior was automatically controlled to make the change smaller/clearer.

dirstate: cover each dirstate version when testing for status race Previously we were only testing it with the default (dirstate-v1 currently). Now we explicitly test each variant.

dirstate: test a `hg status` raced by another `hg status` This shows that `rhg` is misbehaving here.

dirstate: test a `hg status` raced by a `hg update` This shows that `rhg` is misbehaving here.

dirstate: test a `hg status` raced by a `hg commit` This shows that `rhg` is misbehaving here.

dirstate: test a `hg status` raced by a `hg add` This shows that `rhg` is misbehaving here.

dirstate: add a way to test races happening during status We add the `devel.sync.status.pre-dirstate-write-file` config option to easily test what happens when other operations happen during the window where `hg status` is done working but has not updated the cache on disk yet. We introduce the framework for testing such races too, actual tests will be added in the next changesets. For now the test is only checking dirstate-v1. We will extend the test coverage later too. Check test documentation for details. Code change from Raphaël Gomès <rgomes@octobus.net> Test change from Pierre-Yves David <pierre-yves.david@octobus.net>

testing: introduce util function to synchronize concurrent commands on files This is an extension of mechanisms that the tests have been using for a while. To be able to also control the execution in Rust, we introduce utility to perform such `wait_on_file` logic based on some configuration value. This will be used in the tests introduced in the next changesets.

hghave: drop py27 and py35 support These versions of python are no longer supported by Mercurial.

hghave: byteify a path passed to a core API It looks like this predicate isn't used at all(?)

dirstate: add some debug output when writing the dirstate This helps debugging Mercurial behavior in the dirstate-v2 case.

run-tests: make it possible to nest conditionals This is not that hard to implement and makes our life easier on a regular basis.

rust: box ConfigValueParseError to avoid large result types clippy emits a warning that all the Result types are way too large because of HgError includes ConfigValueParseError as one of the variants, so its size is 136 bytes. By boxing ConfigValueParseError we're hopefully making everything faster "for free".

dirstate: drop `identity` from the public API We no longer needs it.

delta-find: rename `delta-reuse-policy` to `pulled-delta-reuse-policy` This make it clearer which type of delta we are talking about.

config-item: declare undeclared path suboption This should prevent issue like the previous commit.

delta-find: declare the "paths..*:delta-reuse-policy option While looking into renaming the option I realized it was not declared.

delta-find: adjust the default candidate group chunk size We move from 10 to 20 as the default as some usage in the wild saw a small degradation in storage quality when using `10`.

record: extract a closure to the module level This clean up is almost as gratuituous as this closure was.

record: drop a now useless overlay that grab the lock Since 28dfb2df4ab9, commit grab the wlock and the extra layer grabing the lock in record is no longer needed. We clean up the code to make this simpler (and add a small assert for extra security against future change).

bundlerepo: fix string interpolation Matt Harbison is saying we cannot `%s` a type into a byte string and that seems reasonable.

bundlerepo: apply phase data stored in the bundle instead of assuming `draft` The phase information contained in the changegroup part and the explicit `phase-heads` part are now taken in account. Initial changes and test by Matt Harbison, code rework by Pierre-Yves David.

bundlerepo: handle changegroup induced phase movement in the associated method These movement comes from handling the changegroup part, so we keeps the code grouped. This will be important when handling more part (and more changegroup part in the future) This induce a small code duplication, but it does not looks terrible.

bundlerepo: move most attribute declaration earlier in __init__ The expected attribute are clearer this way. The bundle handling code is responsible for setting most of it.

bundlerepo: move the handling of bundl1 in its own method This should make the overall flow simpler to follow.

bundlerepo: expliclty handing cg part from bundle2 We will handle other types of parts soon (phase-heads) so we need some cleanup first.

transaction: use the standard transaction mechanism to backup branch Branch is a bit special : - It currently does not collaborate with the transaction (or any scoping) for writing (this is bad) - It can change without the lock being taken (it is protected by `wlock`) So we rely on the same mechanism as for the backup of the other dirstate file: - we only do a backup if we hold the wlock - we force a backup though the transaction Since "branch" write does not collaborate with the transaction, we cannot back it up "at the last minute" as we do for the dirstate. We have to back it up "upfront". Since we have a backup, the transaction is no longer doing its "quick_abort" and get noisy. Which is quite annoying. To work around this, and to avoid jumping in yet-another-rabbit-hole of "getting branch written properly", I am doing horrible things to the transaction in the meantime. We should be able to get this code go away during the next cycle. In the meantime, I prefer to take this small stop so that we stop abusing the "journal" and "undo" mechanism instead of the proper backup mechanism of the transaction. Also note that this change regress the warning message for the legacy fallback introduced in 2008 when issue902 got fixed in dd5a501cb97f (Mercurial 1.0). I feel like this is fine as issue 902 remains fixed, and this would only affect people deploying a mix of 15 year old Mercurial and modern mercurial, and using branch and rollback extensively.

transaction: no longer explicitly cache bookmarks The transaction file generation is already dealing with the backup for this. So, no need to duplicate such backup.

transaction: no longer explicitly cache phaseroots The transaction file generation is already dealing with the backup for this. So, no need to duplicate such backup.

narrow: enforce that narrow spec is written within a transaction

narrow: write the narrow spec in a transaction during share It will be simpler if all write happens within transaction.

narrow: open the transaction sooner when unbundling That way, the narrow spec changes will be done within a transaction.

narrow: write the narrow spec in a transaction during clone It will be simpler if all write happens within transaction.

narrow: drop the dedicated backup code Now that the transaction manage the writes, we can simply use the transaction for backup. Some extra cleanup to ensure all changes happens within a transaction will be made in the next changesets.

narrow: delegate the dirstate's narrow spec writing to the transaction This make it more transactional and will help us to simplify their backup. The implementation is not great, but it keep the patch simple as this is not the time for a larger refactoring yet.

narrow: delegate the narrow spec writing to the transaction This make it more transactional and will help us to simplify their backup. The implementation is not great, but it keep the patch simple as this is not the time for a larger refactoring yet.

narrow: get the narrow patterns from the repository object instead of disk Relying on disk data make the transactionally of this change complicated, so let us start reading data from other API instead.

narrow: widden the lock context in `tracking` The tracking configuration we modify must be read under lock. So we grab the lock sooner.

narrow: move `only_show` handling sooner in `tracked` This will help us to improve the locking scope in the `tracked` command.

tests: in test-fncache.t, be more tolerant to the "Killed" message format For example, on my box I'm seeing: $TESTTMP.sh: line 250: $pid Killed hg ci -qAm z

convert: use a priority queue for sorting commits, to make sorting faster To achieve this, we turn commit sorters into classes so they can encapsulate state. This reduces the sorting time from ~30s to ~10s on a 500k-commit prefix of a repo I tried to convert. (and probably reduces the time to sort the whole repo from many tens of minutes to minutes, but I didn't try that again) The date caching gets removed because priority queue already caches the key.

dirstate-v2: don't mmap the data file when on NFS `mmap` on NFS will trigger a SIGBUS when the mmap'ed file is deleted, which wouldn't work in our case. Also, the performance advantage of using mmap on NFS is debatable at best.

rust-dirstate: trace append/no append to help debugging

rust: add debug log about skipping dirstate update

test-dirstate: use more robust method to trigger a data-file append The previous method was fragile and somewhat flaky on fast machines.

typing: add the return type hint to pycompat.rangelist() Not bothering with the args, because there are a few overloads and only 2 callers in the codebase, one of which is a test.

typing: add type hints to pycompat.maplist() The typeshed hints define 5 overloads with an increasing number of parameters on the passed function, and then a catchall that ignores the argument list on the passed function and allows an `*iterators` arg. All of our uses are fulfilled by the 1 function + 1 iterable overload, but add the second overload as a hint in case it's needed in the future.

branching: merge stable into default This show that the recent changes on default fixed the issue with transaction overwriting content in `test-transaction-wc-rollback-race.t`

transaction: tests we don't overwrite bookmark activation on abort We actually do not! Great.

transaction: tests we don't overwrite updates on abort spoiler: we do… /o\

transaction: tests we don't overwrite branch changes on abort We actually do not! Great. …Why are doing a backup of the `branch` files at transaction creation then‽

transaction: tests we don't overwrite tracking to changed file on abort spoiler: we do…