zsh_completion: use $_hg_remote_opts after it is defined Before this patch, zsh wouldn't complete --ssh, --remotecmd or --insecure for hg clone. While at it, replace --uncompressed by --stream. Differential Revision: https://phab.mercurial-scm.org/D5140

tests: fix "running x tests using y ... " output in a few more places These seem to have been missed by 1039404c5e1d (run-tests: print number of tests and parallel process count, 2018-10-13). Differential Revision: https://phab.mercurial-scm.org/D5145

py3: fix test-hardlinks.t Differential Revision: https://phab.mercurial-scm.org/D5096

exchange: support declaring pull depth Upcoming commits will teach exchangev2 how to perform a shallow clone. This commit teaches hg.clone(), exchange.pull(), and exchange.pulloperation to recognize a request for a shallow clone by having the caller specify a numeric depth of the maximum number of ancestor changesets to fetch. There are certainly other ways we could control shallow-ness. But this one is simple to implement and is also how the narrow extension controls things. So it seems to make sense to start here. Differential Revision: https://phab.mercurial-scm.org/D5136

exchangev2: support for calling rawstorefiledata to retrieve raw files This is somewhat hacky. For that I apologize. At the 4.8 Sprint, we decided we wanted to land support in wireprotov2 for doing a partial clone with changelog and manifestlog bootstrapped from a "stream clone" like primitive. This commit implements the client-side bits necessary to facilitate that. If the new server-side command for obtaining raw files data is available, we call it to get the raw files for the changelog and manifestlog. Then we fall through to an incremental pull. But when fetching files data, instead of using the list of a changesets and manifests that we fetched via the "changesetdata" command, we do a linear scan of the repo and resolve the changeset and manifest nodes along with the manifest linkrevs. Differential Revision: https://phab.mercurial-scm.org/D5135

wireprotov2: implement command for retrieving raw store files Implementing shallow clone of the changelog is hard. We want the 4.8 release to have a fast implementation of partial clone in wireprotov2. In order to achieve fast, we can't use deltas for transferring changelog and manifestlog data. Per discussions at the 4.8 sprint, this commit implements a somwwhat hacky and likely-to-be-changed-drastically-or-dropped command in wireprotov2 that facilitates access to raw store files, namely the changelog and manifestlog. Using this command, clients can perform a "stream clone" of sorts for just the changelog and manifestlog. This will allow clients to fetch the changelog and manifest revlogs, stream them to disk (which should be fast), then follow up filesdata requests for files revision data for a particular changeset. Differential Revision: https://phab.mercurial-scm.org/D5134

wireprotov2: add response type that serializes to indefinite length bytestring This will be needed in a future patch. Differential Revision: https://phab.mercurial-scm.org/D5133

exchangev2: recognize narrow patterns when pulling pulloperation instances were recently taught to record file include and exclude patterns to facilitate narrow file transfer. Teaching the exchangev2 code to transfer a subset of files is as simple as constructing a narrow matcher from these patterns and filtering all seen file paths through it. Keep in mind that this change only influences file data: we're still fetching all changeset and manifest data. So, there's still a ton of "partial clone" to implement in exchangev2. On a personal note, I derive gratification that this feature requires very few lines of new code to implement. To test this, we implemented a minimal extension which allows us to specify --include/--exclude to clone. While the narrow extension provides these arguments, I explicitly wanted to test this functionality without the narrow extension enabled, as that extension monkeypatches various things and I want to isolate the behavior of core Mercurial. Differential Revision: https://phab.mercurial-scm.org/D5132

sqlitestore: file storage backend using SQLite This commit provides an extension which uses SQLite to store file data (as opposed to revlogs). As the inline documentation describes, there are still several aspects to the extension that are incomplete. But it's a start. The extension does support basic clone, checkout, and commit workflows, which makes it suitable for simple use cases. One notable missing feature is support for "bundlerepos." This is probably responsible for the most test failures when the extension is activated as part of the test suite. All revision data is stored in SQLite. Data is stored as zstd compressed chunks (default if zstd is available), zlib compressed chunks (default if zstd is not available), or raw chunks (if configured or if a compressed delta is not smaller than the raw delta). This makes things very similar to revlogs. Unlike revlogs, the extension doesn't yet enforce a limit on delta chain length. This is an obvious limitation and should be addressed. This is somewhat mitigated by the use of zstd, which is much faster than zlib to decompress. There is a dedicated table for storing deltas. Deltas are stored by the SHA-1 hash of their uncompressed content. The "fileindex" table has columns that reference the delta for each revision and the base delta that delta should be applied against. A recursive SQL query is used to resolve the delta chain along with the delta data. By storing deltas by hash, we are able to de-duplicate delta storage! With revlogs, the same deltas in different revlogs would result in duplicate storage of that delta. In this scheme, inserting the duplicate delta is a no-op and delta chains simply reference the existing delta. When initially implementing this extension, I did not have content-indexed deltas and deltas could be duplicated across files (just like revlogs). When I implemented content-indexed deltas, the size of the SQLite database for a full clone of mozilla-unified dropped: before: 2,554,261,504 bytes after: 2,488,754,176 bytes Surprisingly, this is still larger than the bytes size of revlog files: revlog files: 2,104,861,230 bytes du -b: 2,254,381,614 I would have expected storage to be smaller since we're not limiting delta chain length and since we're using zstd instead of zlib. I suspect the SQLite indexes and per-column overhead account for the bulk of the differences. (Keep in mind that revlog uses a 64-byte packed struct for revision index data and deltas are stored without padding. Aside from the 12 unused bytes in the 32 byte node field, revlogs are pretty efficient.) Another source of overhead is file name storage. With revlogs, file names are stored in the filesystem. But with SQLite, we need to store file names in the database. This is roughly equivalent to the size of the fncache file, which for the mozilla-unified repository is ~34MB. Since the SQLite database isn't append-only and since delta chains can reference any delta, this opens some interesting possibilities. For example, we could store deltas in reverse, such that fulltexts are stored for newer revisions and deltas are applied to reconstruct older revisions. This is likely a more optimal storage strategy for version control, as new data tends to be more frequently accessed than old data. We would obviously need wire protocol support for transferring revision data from newest to oldest. And we would probably need some kind of mechanism for "re-encoding" stores. But it should be doable. This extension is very much experimental quality. There are a handful of features that don't work. It probably isn't suitable for day-to-day use. But it could be used in limited cases (e.g. read-only checkouts like in CI). And it is also a good proving ground for alternate storage backends. As we continue to define interfaces for all things storage, it will be useful to have a viable alternate storage backend to see how things shake out in practice. test-storage.py passes on Python 2 and introduces no new test failures on Python 3. Having the storage-level unit tests has proved to be insanely useful when developing this extension. Those tests caught numerous bugs during development and I'm convinced this style of testing is the way forward for ensuring alternate storage backends work as intended. Of course, test coverage isn't close to what it needs to be. But it is a start. And what coverage we have gives me confidence that basic store functionality is implemented properly. Differential Revision: https://phab.mercurial-scm.org/D4928

storageutil: extract most of peek_censored from revlog This function is super hacky and isn't correct 100% of the time. I'm going to need this functionality on a future non-revlog store. Let's copy things to storageutil so this code only exists once. Differential Revision: https://phab.mercurial-scm.org/D5118