narrow: move adding of narrow server capabilities to core We use the experimental.narrow config option introduced in one of the previous patch and move the functionality of adding narrow server capabilities to core. Differential Revision: https://phab.mercurial-scm.org/D4891

wireprotoserver: move narrow capabilities to wireprototypes.py This is done because wireprotoserver import wireprotov1server, so you cannot import wireprotoserver in wireprotov1server to use the capabilities constants. Differential Revision: https://phab.mercurial-scm.org/D4890

narrow: introduce a config option to check if narrow is enabled or not This patch introduces a new config option experimental.narrow which is set to False by default and set to True by the narrow extension. While moving narrow related logic into core, we need to know at places whether narrow extension is enabled or not. Checking the list of extension enabled is one solution but once narrow is inbuilt, we will definitely want a config option to check whether narrow is turned on or not. So this patch introduces a config option, which will evolve to the main point to turn narrow capability on and off once all the narrow is in core. Differential Revision: https://phab.mercurial-scm.org/D4889

narrow: move the code to generate a widening bundle2 to core This is a part of moving more narrow related bits to core. Differential Revision: https://phab.mercurial-scm.org/D4888

narrow: start returning bundle2 from widen_bundle() Differential Revision: https://phab.mercurial-scm.org/D4838

narrow: the first version of narrow_widen wireprotocol command This patch introduces a wireprotocol command narrow_widen() which will be used to widen a narrow copy using `hg tracked` command provided by narrow extension. The wireprotocol command takes the old and new includes and excludes, common heads, changegroup version, known revs, and a boolean ellipses and generates a bundle2 of the required data and send it. The clients receives the bundle2 and applies that. A bundle2 instead of changegroup because in future we might want to add more things to send while widening. Thanks for martinvonz for the suggestion. I am not sure whether we need changegroup version as an argument to the command as I *think* narrow needs changegroup3 already. The tests shows that we don't exchange phase data now while widening which is nice. Also we don't check for pushkeys, rbc-cache, bookmarks etc. This does not support ellipses cases for now but will be supported in future patches. Since we send bundle2, it won't be hard to plug the ellipses logic in here. The existing code for widening a non-ellipses case is also dropped in this patch. Differential Revision: https://phab.mercurial-scm.org/D4813

remotenames: abort if literal revset pattern matches nothing This is the convention of the other namespace revsets such as tag(). Let's make the remote variants do the same.

remotenames: remove unneeded sorted() from revset implementation The order is constrained by the subset.

remotenames: don't call a set of nodes as "revs"

remotenames: use util.always instead of handcrafted lambda

remotenames: inline _parseargs() into _revsetutil() The _parseargs() function gets quite simple, and the 0/1 loop can be rewritten as "if".

repo: create changectx in a single place in localrepo.__getitem__ Differential Revision: https://phab.mercurial-scm.org/D4885

repo: remove the last few "pass" statements in localrepo.__getitem__ In case of IndexError or LookupError, we used "pass" statements and fell through to the end of localrepo.__getitem__. I find the pass statements easy to miss. Consistently raising and catching exceptions seems easier to follow. Oh -- and I didn't plan this before I wrote the above -- that probably also lets us reuse the "return context.changectx(self, rev, node)" in a later patch. Differential Revision: https://phab.mercurial-scm.org/D4884

filectx: correct docstring about "changeid" The changeid argument must be a revnum (basefile.rev() is defined as "return self._changeid"), so fix the lie in the docstring. It seems to have been incorrect for at least 10 years (I didn't check further back). Differential Revision: https://phab.mercurial-scm.org/D4881

context: drop incorrect and superfluous docstring It's been incorrect at least since 8b86acc7aa64 (context: drop support for looking up context by ambiguous changeid (API), 2018-04-28). Differential Revision: https://phab.mercurial-scm.org/D4880

remotenames: follow-up on D3639 to make revset funcs take only one arg Per the review discussion on D3639, we want this to just take one argument. That ended up simplifying the code, so I'm sharing this as a follow-up to that revision rather than editing in-flight.

remotenames: add names argument to remotenames revset This patch adds names argument to the revsets provided by the remotenames extension. The revsets are remotenames(), remotebranches() and remotebookmarks(). names can be a single names, list of names or can be empty too which means it's an optional argument. If names is/are passed, changesets which have those remotenames will be returned. If names are not passed, changesets from all the remotenames are shown. Passing an invalid remotename does not throw error. The name argument also supports pattern matching. Tests are added for the argument in tests/test-logexchange.t Differential Revision: https://phab.mercurial-scm.org/D3639

copies: add time information to the debug information

copies: add a devel debug mode to trace what copy tracing does Mercurial can spend a lot of time finding renames between two commits. Having more information about that process help to understand what makes it slow in an individual instance. (eg: many files vs 1 file, etc...)

revlog: rewrite censoring logic I was able to corrupt a revlog relatively easily with the existing censoring code. The underlying problem is that the existing code doesn't fully take delta chains into account. When copying revisions that occur after the censored revision, the delta base can refer to a censored revision. Then at read time, things blow up due to the revision data not being a compressed delta. This commit rewrites the revlog censoring code to take a higher-level approach. We now create a new revlog instance pointing at temp files. We iterate through each revision in the source revlog and insert those revisions into the new revlog, replacing the censored revision's data along the way. The new implementation isn't as efficient as the old one. This is because it will fully engage delta computation on insertion. But I don't think it matters. The new implementation is a bit hacky because it attempts to reload the revlog instance with a new revlog index/data file. This is fragile. But this is needed because the index (which could be backed by C) would have a cached copy of the old, possibly changed data and that could lead to problems accessing index or revision data later. One benefit of the new approach is that we integrate with the transaction. The old revlog is backed up and if the transaction is rolled back, the original revlog is restored. As part of this, we had to teach the transaction about the store vfs. I'm not super keen about this. But this was the easiest way to hook things up to the transaction. We /could/ just ignore the transaction like we were doing before. But any file mutation should be governed by transaction semantics, including undo during rollback. Differential Revision: https://phab.mercurial-scm.org/D4869

revlog: move loading of index data into own method This will allow us to "reload" a revlog instance from a rewritten index file, which will be used in a subsequent commit. Differential Revision: https://phab.mercurial-scm.org/D4868

revlog: clear revision cache on hash verification failure The revision cache is populated after raw revision fulltext is retrieved but before hash verification. If hash verification fails, the revision cache will be populated and subsequent operations to retrieve the invalid fulltext may return the cached fulltext instead of raising. This commit changes hash verification so it will invalidate the revision cache if the cached node fails hash verification. The side-effect is that subsequent operations to request the revision text - even the raw revision text - will always fail. The new behavior is consistent and is definitely less wrong. There is an open question of whether revision(raw=True) should validate hashes. But I'm going to punt on this problem. We can always change behavior later. And to be honest, I'm not sure we should expose raw=True on the storage interface at all. Another day... Differential Revision: https://phab.mercurial-scm.org/D4867

fuzz: new fuzzer for cext/manifest.c This is a bit messy, because lazymanifest is tightly coupled to the cpython API for performance reasons. As a result, we have to build a whole Python without pymalloc (so ASAN can help us out) and link against that. Then we have to use an embedded Python interpreter. We could manually drive the lazymanifest in C from that point, but experimentally just using PyEval_EvalCode isn't really any slower so we may as well do that and write the innermost guts of the fuzzer in Python. Leak detection is currently disabled for this fuzzer because there are a few global-lifetime things in our extensions that we more or less intentionally leak and I didn't want to take the detour to work around that for now. This should not be pushed to our repo until https://github.com/google/oss-fuzz/pull/1853 is merged, as this depends on having the Python tarball around. Differential Revision: https://phab.mercurial-scm.org/D4879

revlog: rename _cache to _revisioncache "cache" is generic and revlog instances have multiple caches. Let's be descriptive about what this is a cache for. Differential Revision: https://phab.mercurial-scm.org/D4866

testing: add file storage integration for bad hashes and censoring In order to implement these tests, we need a backdoor to write data into storage backends while bypassing normal checks. We invent a callable to do that. As part of writing the tests, I found a bug with censorrevision() pretty quickly! After calling censorrevision(), attempting to access revision data for an affected node raises a cryptic error related to malformed compression. This appears to be due to the revlog not adjusting delta chains as part of censoring. I also found a bug with regards to hash verification and revision fulltext caching. Essentially, we cache the fulltext before hash verification. If we look up the fulltext after a failed hash verification, we don't get a hash verification exception. Furthermore, the behavior of revision(raw=True) can be inconsistent depending on the order of operations. I'll be fixing both these bugs in subsequent commits. Differential Revision: https://phab.mercurial-scm.org/D4865

testing: add file storage tests for getstrippoint() and strip() Differential Revision: https://phab.mercurial-scm.org/D4864

wireprotov2: always advertise raw repo requirements I'm pretty sure my original thinking behind making it conditional on stream clone support was that the behavior mirrored wire protocol version 1. I don't see a compelling reason for us to not advertise the server's storage requirements. The proper way to advertise stream clone support in wireprotov2 would be to not advertise the command(s) required to perform stream clone or to advertise a separate capability denoting stream clone support. Stream clone isn't yet implemented on wireprotov2, so we can cross this bridge later. Differential Revision: https://phab.mercurial-scm.org/D4863

tests: don't be as verbose in wireprotov2 tests I don't think that printing low-level I/O and frames is beneficial to testing command-level functionality. Protocol-level testing, yes. But command-level functionality shouldn't care about low-level details in most cases. This output makes tests more verbose and harder to read. It also makes them harder to maintain, as you need to glob over various dynamic width fields. Let's remove these low-level details from many of the wireprotov2 tests. Differential Revision: https://phab.mercurial-scm.org/D4861

repository: define and use revision flag constants Revlogs have a per-revision 2 byte field holding integer flags that define how revision data should be interpreted. For historical reasons, these integer values are sent verbatim on the wire protocol as part of changegroup data. From a semantic standpoint, the flags that go out over the wire are different from the flags stored internally by revlogs. Failure to establish this semantic distinction creates unwanted strong coupling between revlog's internals and the wire protocol. This commit establishes new constants on the repository module that define the revision flags used by the wire protocol (and by some internal storage APIs, sadly). The changegroups internals documentation has been updated to document them explicitly. Various references throughout the repo now use the repository constants instead of the revlog constants. This is done to make it clear that we're operating on generic revision data and this isn't tied to revlogs. Differential Revision: https://phab.mercurial-scm.org/D4860

context: reverse conditional branch order in introrev Positive logic will be simpler to follow. It will help to clarify coming refactoring.