dumbhttp: use IPv6 if HGIPV6 is set to 1 This will fix flaky tests using dumbhttp. The patch was tested on gcc112.fsffrance.org using the following command: ./run-tests.py -j 40 --runs-per-test 120 test-bundle2-remote-changegroup.t

runtests: export HGIPV6 to hint test scripts whether to use IPv6 Previously, run-tests.py only exports HGPORT, and scripts in tests do not know if IPv6 should be used. And that breaks scripts like dumbhttp.py which always uses IPv4. This patch makes run-tests.py export HGIPV6, which can help test scripts like dumbhttp.py and tinyproxy.py to decide whether to use IPv6 or not.

runtests: prefer IPv4 to IPv6 To make IPv6 work, there are multiple areas that need to fix. Before they all get fixed, use IPv4 by default. This should fix tests caused on IPv6 systems.

doc: correct example concerning "hg purge" alias in man page "hgrc.5" The "hg purge" alias as currently described in "hgrc.5" issues a possibly confusing error message like rm: missing operand Try 'rm --help' for more information. if no files are to be purged at all. This patch slightly modifies the example by adding a "-f" option to the "rm" command.

tests: prove that ignore works

annotate: migrate to modern pager API

ui: add a debug print right before we start the pager This makes it easier to figure out why a command is getting paginated.

ui: respect historic pager.attend-$COMMAND=no I'm on the fence about this behavior, but the user's intent was pretty specific and it's not expensive to support this case.

tests: clean up a bunch of pager testing that is about to be invalidated All this attend logic and potential bugs just no longer make sense to test.

ui: add ignore-single-command functionality This closes the last feature gap other than the attend list from the extension. For now, I'm leaving the attend list in the extension, because I'm unsure it has merit in a world where commands have been updated to take advantage of the modern API.

ui: introduce neverpager() call I'm about to add direct paging support to some commands, and as a result we need a way to communicate from the higher layers of dispatch that paging is explicitly disabled.

pager: move more behavior into core This moves the global flag and the --pager=yes logic into core. Only functionality change is that users now always get a --pager flag and can enable the pager via the flag without the extension active. Moving the flag into core exposes a defect in the ro localization, which will have to be corrected later.

pager: move pager-initiating code into core No functionality change. A previous version of this API had a category argument on ui.pager(). As I migrated the commands in core, I couldn't come up with good enough consistency in any categorization scheme so I just scrapped the whole idea. It may be worth revisiting in the future.

test-logtoprocess: use cat to wait for outputs Commands started by logtoprocess are running asynchronously. To be able to test the output, we need to block and wait for the output. The patch uses "| cat" to wait for such "asynchronous" outputs, to make the test more reliable. I have also written a short notice at the top, hopefully people would be aware of the pitfall when changing the test.

chgserver: move comments in config example "#" must be the first character of a line to mark the text as comments. So let's change the docstring.

localrepo: move extension loading to a separate method The stateful chg plan [1] requires a special repo object, where ideally all side effects caused by loading the repo object could be reverted by just dropping (gabbage collect) the loaded repo object. Currently, that is impossible because repo.__init__ calls "extensions.loadall", which may have unpredictable side-effects that cannot be reverted by dropping the repo object. This patch moves "extensions.loadall" to a separate method, so chg could subclass localrepository and make extensions loading a no-op. [1]: mercurial-scm.org/pipermail/mercurial-devel/2017-February/092547.html

py3: convert the mode argument of os.fdopen to unicodes Couple of these from the earlier series got lost while rebasing. So this patch converts them again.

runtests: unindent an "if True" block The block was left to make review easier. This patch unindents it.

runtests: set web.ipv6 if we use IPv6 As explained by the previous patch, we need to set "web.ipv6=True" if we decide to use IPv6. Otherwise "hg serve" will still try to listen on IPv4. This patch makes it so by appending web.ipv6 to "extra configs". This patch was tested in a Linux system with IPv6, by the following steps: 1. Change hgweb/server.py temporarily to write a file if IPv6HTTPServer.__init__ is called. 2. run-tests.py -l --keep-tmpdir test-serve.t 3. Check the generated .hgrc, make sure it sets web.ipv6=1. 4. Check the log file to make sure IPv6HTTPServer.__init__ is called.

runtests: checkportisavailable should only check one family As explained by the previous patch, checkportisavailable() should only check the preferred family - either IPv4 or IPv6, not both. This patch makes it so.

runtests: add a function to test if IPv6 is available Previously, checkportisavailable returns True if the port is free either on IPv4 or IPv6, but the hg server only uses IPv4 by default. That leads to issues when IPv4 port is not free but the IPv6 one is. To address that, run-tests should stick with either IPv4 or IPv6. This patch adds a function similar to checkportisavailable to test if IPv6 is available, and assigns the result to a variable. The new function was tested in a Linux system script with the following steps: 1. Run "ip addr del ::1/128 dev lo" to delete lo's IPv6 address, Confirm checkipv6available() returns False. 2. Run "ip addr add ::1/128 dev lo" to add back lo's IPv6 address. Confirm checkipv6available() returns True. 3. Start a web server taking the 8000 port. Confirm checkipv6available(8000) is still True.

histedit: log the time taken to read in the commands list If we're being fed an external command list from stdin (histedit --commands -), then the time spent reading stdin is outside our control. Log it.

extdiff: log time spent in external diff program We can't fix the time external diff programs take to run. Log that duration for us to remove from any stats we gather

crecord: log blocked time waiting for curses input We want to know when we're blocked waiting for the user - log the time spent waiting in the curses keyboard handlers

ui: give editor() a tag of its own We know that calls to ui.editor() always block on the user's configured editor. Use a blocking tag that ensures that we don't see a huge variety of editor options in our logging.

ui: time calls to ui.system We want to know when we're blocked on ui.system, and why. Allow the user to supply a tag - otherwise we record on an unspecific tag derived from cmd.

ui: log time spent blocked on stdio We use a wrapper around Mercurial at Facebook that logs key statistics (like elpased time) to our standard performance tooling. This is less useful than it could be, because we currently can't tell when a command is slow because we need to fix Mercurial versus when a command is slow because the user isn't interacting quickly. Teach Mercurial to log the time it spends blocked, so that our tooling can pick it up and submit it with the elapsed time - we can then do the math in our tooling to see if Mercurial is slow, or if the user simply failed to interact. Combining this with the command duration log means that we can ensure that we concentrate performance efforts on the things that bite Facebook users. The perfwrite microbenchmark shifts from: Linux: ! wall 3.213560 comb 0.410000 user 0.350000 sys 0.060000 (best of 4) Mac: ! wall 0.342325 comb 0.180000 user 0.110000 sys 0.070000 (best of 20) before this change to: ! wall 3.478070 comb 0.500000 user 0.420000 sys 0.080000 (best of 3) Mac: ! wall 0.218112 comb 0.220000 user 0.150000 sys 0.070000 (best of 15) showing a small hit in comb time, but firmly in the noise on wall time.

contrib: add a write microbenchmark to perf.py I'm adding some performance logging to ui.write - this benchmark lets us confirm that the cost of that logging is acceptably low. At this point, the microbenchmark on Linux over SSH shows: ! wall 3.213560 comb 0.410000 user 0.350000 sys 0.060000 (best of 4) while on the Mac locally, it shows: ! wall 0.342325 comb 0.180000 user 0.110000 sys 0.070000 (best of 20)

ui: provide a mechanism to track and log blocked time We want to log the time Mercurial spends trapped in things outside programmatic control. Provide a mechanism to give us both command runtime and as many different sources of blocking as we deem useful.

mercurial: switch to util.timer for all interval timings util.timer is now the best available interval timer, at the expense of not having a known epoch. Let's use it whenever the epoch is irrelevant.