worker: ability to disable thread unsafe tasks The worker on Windows is implemented using a thread pool. If worker tasks are not thread safe, badness can occur. In addition, if tasks are executing CPU bound code and holding onto the GIL, there will be non-substantial overhead in Python context switching between active threads. This can result in significant slowdowns of tasks. This commit teaches the code for determining whether to use a worker to take thread safety into account. Effectively, thread unsafe tasks don't use the thread-based worker on Windows. Differential Revision: https://phab.mercurial-scm.org/D3962

worker: rename variable to reflect constant Differential Revision: https://phab.mercurial-scm.org/D3961

worker: use one pipe per posix worker and select() in parent process This allows us to pass results larger than PIPE_BUF through the pipes without interleaving them. This is necessary now because "hg fix" sends file contents as the result from workers. Differential Revision: https://phab.mercurial-scm.org/D3960

tests: refactor common bundle2 capabilities Differential Revision: https://phab.mercurial-scm.org/D1945

debug: move extensions debug behind a dedicated flag Since b86664c81833, we process the `--debug` flag earlier. This is overall good and useful, but has at least one negative side effect. Previously the debug message we report when trying to import extensions were issued before we processed the `--debug` flag. Now they happen after. Before: $ ./hg id --debug 21f507b8de2f9c1606e9aeb5ec7d2a6dedb7a4a7 tip After: $ ./hg id --debug ☿ (revset-bench) could not import hgext.evolve (No module named evolve): trying hgext3rd.evolve could not import hgext.mercurial_keyring (No module named mercurial_keyring): trying hgext3rd.mercurial_keyring could not import hgext3rd.mercurial_keyring (No module named mercurial_keyring): trying mercurial_keyring could not import hgext.hggit (No module named hggit): trying hgext3rd.hggit could not import hgext3rd.hggit (No module named hggit): trying hggit 21f507b8de2f9c1606e9aeb5ec7d2a6dedb7a4a7 tip (This get worse if --traceback is used). To work around this, we move this extensions related debug message behind a new flag 'devel.debug.extensions' and restore the previous output. I'm not fully happy about using the 'devel' section for a flag that can be used by legitimate users to debug extensions issues. However, it fits well next to other `devel.devel.*` options and is mostly used by extensions author anyway. We might move it to another, more appropriate section in the future (using alias).

curses: use "text" interface if TERM=dumb Differential Revision: https://phab.mercurial-scm.org/D3948

windows: expand '~/' and '~\' to %USERPROFILE% when translating to cmd.exe It's convenient to be able to reference hooks in a portable location on any platform.

windows: replace single quote with double quote when translating to cmd.exe Since cmd.exe doesn't understand single quotes, single quotes to prevent $var expansion is basically unusable without this. Single quote isn't allowed in a path name, so it seems unlikely to come up otherwise.

hook: only print the note about native cmd translation if it actually changes This makes it so that it will never occur on a non Windows platform.

hook: disable the shell to native command translation by default There are other things I want to add like ~ expansion and translating single to double quotes for cmd.exe. So off by default is safer. I'm having second thoughts about the name, but I don't have any better ideas.

setup: allow to run setup.py with python 3 without a mercurial checkout Some people may want to test mercurial in a python 3 environment through e.g. pip, in which case setup.py doesn't run in a mercurial checkout, so the hack in setup.py to allow python 3 cannot be overcome. This change allows a manual override with the HGPYTHON3 environment variable. Additionally, when for some reason the version is unknown (for crazy people like me, who have a git checkout of the mercurial repo), the version variable ends up being an unicode string, which fails the `isinstance(version, bytes)` assertion. So fix that at the same time. Differential Revision: https://phab.mercurial-scm.org/D3958

upgrade: enable adding or removing sparse-revlog requirement

upgrade: add information about sparse-revlog Show information about sparse-revlog in debugformat, just like other requirements.

sparse-revlog: implement algorithm to write sparse delta chains (issue5480) The classic behavior of revlog._isgooddeltainfo is to consider the span size of the whole delta chain, and limit it to 4 * textlen. Once sparse-revlog writing is allowed (and enforced with a requirement), revlog._isgooddeltainfo considers the span of the largest chunk as the distance used in the verification, instead of using the span of the whole delta chain. In order to compute the span of the largest chunk, we need to slice into chunks a chain with the new revision at the top of the revlog, and take the maximal span of these chunks. The sparse read density is a parameter to the slicing, as it will stop when the global read density reaches this threshold. For instance, a density of 50% means that 2 of 4 read bytes are actually used for the reconstruction of the revision (the others are part of other chains). This allows a new revision to be potentially stored with a diff against another revision anywhere in the history, instead of forcing it in the last 4 * textlen. The result is a much better compression on repositories that have many concurrent branches. Here are a comparison between using deltas from current upstream (aggressive-merge-deltas on by default) and deltas from a sparse-revlog Comparison of `.hg/store/` size: mercurial (6.74% merges): before: 46,831,873 bytes after: 46,795,992 bytes (no relevant change) pypy (8.30% merges): before: 333,524,651 bytes after: 308,417,511 bytes -8% netbeans (34.21% merges): before: 1,141,847,554 bytes after: 1,131,093,161 bytes -1% mozilla-central (4.84% merges): before: 2,344,248,850 bytes after: 2,328,459,258 bytes -1% large-private-repo-A (merge 19.73%) before: 41,510,550,163 bytes after: 8,121,763,428 bytes -80% large-private-repo-B (23.77%) before: 58,702,221,709 bytes after: 8,351,588,828 bytes -76% Comparison of `00manifest.d` size: mercurial (6.74% merges): before: 6,143,044 bytes after: 6,107,163 bytes pypy (8.30% merges): before: 52,941,780 bytes after: 27,834,082 bytes -48% netbeans (34.21% merges): before: 130,088,982 bytes after: 119,337,636 bytes -10% mozilla-central (4.84% merges): before: 215,096,339 bytes after: 199,496,863 bytes -8% large-private-repo-A (merge 19.73%) before: 33,725,285,081 bytes after: 390,302,545 bytes -99% large-private-repo-B (23.77%) before: 49,457,701,645 bytes after: 1,366,752,187 bytes -97% The better delta chains provide a performance boost in relevant repositories: pypy, bundling 1000 revisions: before: 1.670s after: 1.149s -31% Unbundling got a bit slower. probably because the sparse algorithm is still pure python. pypy, unbundling 1000 revisions: before: 4.062s after: 4.507s +10% Performance of bundle/unbundle in repository with few concurrent branches (eg: mercurial) are unaffected. No significant differences have been noticed then timing `hg push` and `hg pull` locally. More state timings are being gathered. Same as for aggressive-merge-delta, better delta comes with longer delta chains. Longer chains have a performance impact. For example. The length of the chain needed to get the manifest of pypy's tip moves from 82 item to 1929 items. This moves the restore time from 3.88ms to 11.3ms. Delta chain length is an independent issue that affects repository without this changes. It will be dealt with independently. No significant differences have been observed on repositories where `sparse-revlog` have not much effect (mercurial, unity, netbeans). On pypy, small differences have been observed on some operation affected by delta chain building and retrieval. pypy, perfmanifest before: 0.006162s after: 0.017899s +190% pypy, commit: before: 0.382 after: 0.376 -1% pypy, status: before: 0.157 after: 0.168 +7% More comprehensive and stable timing comparisons are in progress.

sparse-revlog: new requirement enabled with format.sparse-revlog The meaning of the new 'sparse-revlog' requirement is that the revlogs are allowed to contain wider delta chains with larger holes between the interesting chunks. These sparse delta chains should be read in several chunks to avoid a potential explosion of memory usage. Former version won't know how to read a delta chain in several chunks. They would keep reading them in a single read, and therefore would be subject to the potential memory explosion. Hence this new requirement: only versions having support of sparse-revlog reading should be allowed to read such a revlog. Implementation of this new algorithm and tools to enable or disable the requirement will follow in the next changesets.

revlog: extract `deltainfo.distance` for future conditional redefinition This commit exist to make the next one clearer.

shelve: pick the most recent shelve if none specified for --patch/--stat Differential Revision: https://phab.mercurial-scm.org/D3950

shelve: improve help text for --patch and --stat It's not currently obvious why "hg shelve -p" fails, since -p doesn't take an argument. Differential Revision: https://phab.mercurial-scm.org/D3949

ssh: avoid reading beyond the end of stream when using compression Compressed streams can be used as part of getbundle. The normal read() operation of bufferedinputpipe will try to fulfill the request exactly and can deadlock if the server sends less as it is done. At the same time, the bundle2 logic will stop reading when it believes it has gotten all parts of the bundle, which can leave behind end of stream markers as used by bzip2 and zstd. To solve this, introduce a new optional unbufferedread interface and provided it in bufferedinputpipe and doublepipe. If there is buffered data left, it will be returned, otherwise it will issue a single read request and return whatever it obtains. Reorganize the decompression handlers to try harder to read until the end of stream, especially if the requested read can already be fulfilled. Check for end of stream is messy with Python 2, none of the standard compression modules properly exposes it. At least with zstd and bzip2, decompressing will remember EOS and fail for empty input after the EOS has been seen. For zlib, the only way to detect it with Python 2 is to duplicate the decompressobj and force some additional data into it. The common handler can be further optimized, but works as PoC. Differential Revision: https://phab.mercurial-scm.org/D3937

revset: add larger test for heads(ancestors(…)) It is important to not regress on this benchmark so we move it into the "base" file. And we add another benchmark with more than two revisions.

revset-benchmark: use a generic revset to test `heads(commonancestors())` This allow to benchmark revset performance in other repositories than just the mercurial one.

revlog: reintroduce `revlog.descendant` as deprecated Reintroduce `revlog.descendant` to help extensions authors update their extensions in order to use the new API.

context: reintroduce `ctx.descendant` as deprecated Reintroduce `ctx.descendant` to help extensions authors update their extensions in order to use the new API.

obsolete: explode if metadata contains invalid UTF-8 sequence (API) The current metadata API can be a source of bugs since it forces callers to process encoding conversion by themselves. So let's make it reject bad data as a last ditch. I assume there's no metadata field which is supposed to store arbitrary BLOB like transplant_source.

obsolete: store user name and note in UTF-8 (issue5754) (BC) Before, user names were stored in local encoding and transferred across repositories, which made it impossible to restore non-ASCII user names on different platforms. This patch fixes new markers to be encoded in UTF-8 and decoded back to local encoding when displaying. Existing markers are unfixable so they may result in mojibake. I don't like the API that requires metadata dict to be UTF-8 encoded, which is a source of bugs, but there's no abstraction layer to process the encoding thingy efficiently. So we apply the same rule as extras dict to obsstore metadata.

obsolete: clarify users in markerusers() never contain None

revset: special case commonancestors(none()) to be empty set This matches the behavior of ancestor(none()). From an implementation perspective, ancestor() and commonancestors() are intersection, and ancestors() is union, so it would make some sense that commonancestors(none()) returned all revisions. However, ancestor(none()) isn't implemented as such, which breaks ancestor(x) == max(commonancestors(x)). From a user perspective, ancestors of nothing is nothing whichever type of operation the ancestor predicate does.

revset: clarify heads() order doesn't matter while computing common ancestors Follows up 5460926352ee and 52f19a840543.

hghave: require clang-format >= 6 due to output change

cext: reformat with clang-format 6.0 It appears some changes in clang-format affect our code. I didn't dig into that deeper since the new output looks better.