loggingutil: document openlogfile() This function will be used later for command-server logging.

loggingutil: extract openlogfile() and proxylogger to new module This module isn't placed under the "utils" package since it needs "ui" to process things. It's called "loggingutil", not "logutil" because the word "log" is too obscure in our codebase.

blackbox: pass in options to _openlogfile() as arguments This prepares for extracting utility function from the blackbox module.

blackbox: just try writing to repo.vfs and update lastlogger on success This is simpler and more robust. Before, an empty ".hg" directory would be created if it's removed after checking vfs.isdir('.').

vfs: add option to not create parent directories implicitly In blackbox, we don't want to create a ".hg" directory by mistake. This provides a race-safe option to achieve that.

repo: add a `wcachevfs` to access the `.hg/wcache/` directory This wvfs will allow us to migrate various cache to the new `wcache` directory. Helping with cache issues with "share".

cache: create `wcache` directory at init time The cache directory will be needed very quickly, so it seems simpler to create it early to make sure it has the same owner and permission than the other directory in the repository.

cache: create `cache` directory at init time The cache directory will be needed very quickly, so it seems simpler to create it early to make sure it has the same owner and permission than the other directory in the repository.

check-exec: write file in 'wcache' instead of 'cache' Some cache are relevant or affected by the working copy used. So the `.hg/cache` directory is not the best place for them because multiple shared repository can end up fighting over them. To address this issue, we introduce a new 'wcache' directory to host this kind of cache. The first user are the `checkisexec` type file. These files describe property of the working copy and fit the use-case well.

mmapindex: set default to 1MB mmapping index is more efficient if we only need a small part of it. The 1MB value has been picked arbitrarily, a lower value might be better. On a large repository with a 60MB index, we see the following performance gain: hg perfindex before: ! wall 0.032023 comb 0.040000 user 0.000000 sys 0.040000 (best of 100) after: ! wall 0.000196 comb 0.000000 user 0.000000 sys 0.000000 (best of 1060) The speed boost benefit all cases, including the one where the full index needs to be parsed. hg perfindex --rev 0 before: ! wall 0.040673 comb 0.030000 user 0.000000 sys 0.030000 (best of 100) after ! wall 0.010713 comb 0.020000 user 0.010000 sys 0.010000 (best of 212) This gain reflect in higher level operation: hg perfbookmarks --clear-revlogs before: ! wall 0.161339 comb 0.160000 user 0.130000 sys 0.030000 (best of 56) after: ! wall 0.123228 comb 0.120000 user 0.120000 sys 0.000000 (best of 68)