configitems: restore alias for format.aggressivemergedeltas 913ca175c4ae broke BC by dropping support for reading format.aggressivemergedeltas. Let's restore it. Differential Revision: https://phab.mercurial-scm.org/D3966

worker: call selector.close() to release polling resources

release: merge default into stable for 4.7 release freeze

histedit: drop --no-backup option Dropping this option because now we have a better option than passing --no-backup flag every time, now user can set a config in hgrc: [ui] history-editing-backup = False This config aims to operate on every history editing command and it is still work in progress. As yuya suggessted it probably to late to add full support this config, so making this as an experimental config. Differential Revision: https://phab.mercurial-scm.org/D3965

aggressivemergedelta: document rename and move to `revlog` section The config does not follow our naming guideline and "Aggressive" is probably a word to keep away from users. The option does not truly fit in the `format` section. It can be turned on and off for existing repository without much consequence regarding compatibility. A new `revlog` option is created to control behavior related to revlog writing and reading. We can see multiple other config options that could be migrated there. * format.maxchainlen * experimental.mmapindexthreshold * experimental.sparse-read.density-threshold (in an updated form) * experimental.sparse-read.min-gap-size (in an updated form) In addition, we can foresee at least a couple of sparse-revlog related option coming too (to reduce delta chain length and increase snapshot reuse) These two extra options might fit there too. Unless we want to create a section dedicated to caches and performance. * format.chunkcachesize * format.manifestcachesize For now, we only migrate `optimize-delta-parent-choice` since it is getting out of experimental. It is too close to the release to move the other one. In addition, we still lack proper the prioritization of alias that would help renaming them without bad consequence for users. (Not fully happy about the `revlog` name but could not find better).

aggressivemergedeltas: rename variable internally The "aggressivemergedeltas" name is not great. First, it is quite long, second, we would rather have less "Aggressive" names within the project. We are about to rename the config option, so it seems the appropriate time to rename the internal variable.

config: document the purpose of the `format` config section The config section now have a top level documentation to clarify its intend and usage. In particular, user are now explain when the option are taken in account and how to convert repository. There are an handful of experimental options in this section that does not match its definition. They should be relocated to other section before getting out of experimental. (see next changeset for one example).

macosx: fixing macOS version generation after db9d1dd01bf0 With the Python3 change, the string is now something like version = b'4.6.2+848-88be288e8ac1' where it was previously just: version = '4.6.2+848-88be288e8ac1' Differential Revision: https://phab.mercurial-scm.org/D3964

histedit: add history-editing-backup config option Instead of passing --no-backup option every time you don't want to store backup, now you can set config option: [ui] history-editing-backup = False This option aims to operate on every history editing command. Differential Revision: https://phab.mercurial-scm.org/D3901

merge: mark file gets as not thread safe (issue5933) In default installs, this has the effect of disabling the thread-based worker on Windows when manifesting files in the working directory. My measurements have shown that with revlog-based repositories, Mercurial spends a lot of CPU time in revlog code resolving file data. This ends up incurring a lot of context switching across threads and slows down `hg update` operations when going from an empty working directory to the tip of the repo. On mozilla-unified (246,351 files) on an i7-6700K (4+4 CPUs): before: 487s wall after: 360s wall (equivalent to worker.enabled=false) cpus=2: 379s wall Even with only 2 threads, the thread pool is still slower. The introduction of the thread-based worker (02b36e860e0b) states that it resulted in a "~50%" speedup for `hg sparse --enable-profile` and `hg sparse --disable-profile`. This disagrees with my measurement above. I theorize a few reasons for this: 1) Removal of files from the working directory is I/O - not CPU - bound and should benefit from a thread pool (unless I/O is insanely fast and the GIL release is near instantaneous). So tests like `hg sparse --enable-profile` may exercise deletion throughput and aren't good benchmarks for worker tasks that are CPU heavy. 2) The patch was authored by someone at Facebook. The results were likely measured against a repository using remotefilelog. And I believe that revision retrieval during working directory updates with remotefilelog will often use a remote store, thus being I/O and not CPU bound. This probably resulted in an overstated performance gain. Since there appears to be a need to enable the thread-based worker with some stores, I've made the flagging of file gets as thread safe configurable. I've made it experimental because I don't want to formalize a boolean flag for this option and because this attribute is best captured against the store implementation. But we don't have a proper store API for this yet. I'd rather cross this bridge later. It is possible there are revlog-based repositories that do benefit from a thread-based worker. I didn't do very comprehensive testing. If there are, we may want to devise a more proper algorithm for whether to use the thread-based worker, including possibly config options to limit the number of threads to use. But until I see evidence that justifies complexity, simplicity wins. Differential Revision: https://phab.mercurial-scm.org/D3963