hg: extract post share update logic into own function A future patch will introduce a new caller that needs to perform an update. Extract the code so we don't duplicate it.

merge: perform background file closing in batchget As 2fdbf22a1b63 demonstrated with stream clones, closing files on background threads on Windows can yield a significant speedup because closing files that have been created/appended to is slow on Windows/NTFS. Working directory updates can write thousands of files. Therefore it is susceptible to excessive slowness on Windows due to slow file closes. This patch enables background file closing when performing working directory file writes. The impact when performing an `hg up tip` on mozilla-central (136,357 files) from an empty working directory is significant: Before: 535s (8:55) After: 133s (2:13) Delta: -402s (6:42) That's a 4x speedup! By comparison, that same machine can perform the same operation in ~15s on Linux. So Windows went from ~35x to ~9x slower. Not bad but there's still work to do. As a reminder, background file closing is only activated on Windows because it is only beneficial on that platform. So this patch shouldn't change non-Windows behavior at all. It's worth noting that non-Windows systems perform working directory updates with multiple processes. Unfortunately, worker.py doesn't yet support Windows. So, there is still plenty of room for making working directory updates faster on Windows. Even if multiple processes are used on Windows, I believe background file closing will still provide a benefit, as individual processes will still be slowed down by the file close bottleneck (assuming the I/O system isn't saturated).

merge: indent code in batchget() To make the next patch easier to read.

localrepo: support background closing for wwrite() So working copy update can pass it in.

scmutil: support background closing for write() Upcoming patches will add background file closer support to working copy update. This patch adds some plumbing to prepare for that.

chg: hold a lock file before connected to server This is a part of the one server per config series. In multiple-server setup, multiple clients may try to start different servers (on demand) at the same time. The old lock will not guarantee a client to connect to the server it just started, and is not crash friendly. This patch addressed above issues by using flock and does not release the lock until the client actually connects to the server or times out.

serve: allow --daemon-postexec to be 'unlink:path' or 'none' This patch changes the format of value of --daemon-postexec. Now it can be either to unlink a file, or a no-op. The following patch will make chg to use the no-op option.

serve: rename --daemon-pipefds to --daemon-postexec (BC) Initially we use --daemon-pipefds to pass file descriptors for synchronization. Later, in order to support Windows, --daemon-pipefds is changed to accept a file path to unlink instead. The name is outdated since then. chg client is designed to use flock, which will be held before starting a server and until the client actually connects to the server it started. The unlink synchronization approach is not so helpful in this case. To address the issues, this patch renames pipefds to postexec and the following patch will allow the value of --daemon-postexec to be things like 'unlink:/path/to/file' or 'none'.

largefiles: don't explicitly list optional parameters that are not used This makes it easier for changes to the API.

revert: properly revert to ancestor of p2 during merge (issue5052) During merge, added (from one perspective) file can be reported as "modified". To work around that, revert was testing if modified file were present in the parent manifest and marking them as "added" in this case. However, we should be checking against the target revision manifest instead. Otherwise see file as "newly added" even if they exist in the target revision. That revert behavior regressed in 06fbd9518bc5.