rebase: correctly check for empty commit in in-memory mode The new code has a small overhead in the empty commit case, as a `memctx` object is always created, but I don’t think it’s justified here to duplicate code to optimize a relatively unlikely code path. Differential Revision: https://phab.mercurial-scm.org/D8732

memctx: make `parents()` return list of one element if it’s not a merge It is part of the contract of `parents()` that non-merges return a list of one element. `self._parents` is always a list of two elements in `memctx`. Differential Revision: https://phab.mercurial-scm.org/D8731

commit: factor out empty commit check to `basectx.isempty()` This enables reuse in other places, e.g. those dealing with `memctx`. Differential Revision: https://phab.mercurial-scm.org/D8729

overlayworkingctx: rename misleadingly named `isempty()` method This method is only about whether there are file changes, not about whether the commit will be empty or not. One user of the method was incorrectly assuming the latter meaning, leading to the bug for which a test case was added in D8727. I’ve added a FIXME to the code. The original motivation for the rename was that I want to add `committablectx.isempty()`, that properly checks if a commit will be empty, using the exact same logic as in `repo.commit()`, and I wanted to avoid a name clash. Differential Revision: https://phab.mercurial-scm.org/D8728

rebase: add test case that shows that inmemory rebase does not preserve merges Differential Revision: https://phab.mercurial-scm.org/D8727

rebase: remove now unnecessary logic to allow empty commit when branch changes This was a workaround for a bug in the empty commit check in repo.commit(), where the parent branch name was incorrectly compared with the wdir branch name instead of the branch name passed via `extra`. The bug was fixed in D8724. The workaround was introduced in b2415e94b2f5. Differential Revision: https://phab.mercurial-scm.org/D8725

commit: check branch change on to-be-committed changeset This makes a difference when a branch name is passed via the `extra` argument, which will be used as the branch name for the created changeset. The empty commit check should use that branch name instead of whatever was set on the working directory. Besides fixing the bug for which a test case was extended, it enables to remove a workaround in the rebase extension, which will be done in a follow-up patch (D8725). Differential Revision: https://phab.mercurial-scm.org/D8724

merge with stable

procutil: move comment closer to relevant code

procutil: use mercurial.windows.winstdout only on Python 2 and TTYs Python 3 already works around the bug. The workaround is only needed when writing to consoles. If stdout is a console, sys.stdout.isatty() is true.

procutil: split if condition This prepares the code for subsequent changes where we need to differentiate between the two cases.

procutil: explain better why line buffering is not possible The sentence “On Python 3, buffered binary streams can't be set line-buffered.” was imprecise, as all streams are just Python classes and we can implement our own (which we did).

tests: make subprocess handling reusable for different tests in test-stdio.py

procutil: back out 8403cc54bc83 (make ....procutil.stderr unbuffered) Changeset 8403cc54bc83 introduced code that opens a second file object referring to the stderr file descriptor. This broke tests on Windows. The reason is that on Windows, sys.stderr is buffered and procutil.stderr closed the file descriptor when it got garbage collected before sys.stderr had the chance to flush buffered data. `procutil.stdout` had the same problem for a long time, but we didn’t realize, as in CI test runs, stdout is not a TTY and in this case no second file object is opened.

test-clone-uncompressed: use config to silence the lock warning The ui.timeout.warn option can solve the issue6237 in a cleaner way than what was done in 752da6863e39. That way, possible other unexpected error output will not be silenced. Differential Revision: https://phab.mercurial-scm.org/D8726

hooklib: fix detection of successors for changeset_obsoleted Provide a hook for obsutil.getobsolete to be used with either a transaction or the changes item of the transaction, since hooks only have access to the latter. Use that to find the correct list of revisions with obsmarkers, even new ones, and then filter out revisions with known successors. Move the processing from pretxnclose to txnclose as the transaction access itself is no longer necessary. This is more in line with notify and ensures that sanity checks can abort the transaction first. Differential Revision: https://phab.mercurial-scm.org/D8575

fix: prefetch file contents This prevents the worker subprocesses from contacting the server individually, which is either inefficient, or leads to problems if the connection is shared among them. Differential Revision: https://phab.mercurial-scm.org/D8723

fix: obtain base paths before starting workers This moves calculation of base paths to before work is dispatched. While this does mean that copy tracing will be serialized instead of parallel, it is necessary to be able to prefetch the base contents in a batch, which will likely be more efficient. Differential Revision: https://phab.mercurial-scm.org/D8722

scmutil: allowing different files to be prefetched per revision The old API takes a list of revision separate from the file matcher, and thus provides no way to fetch different sets of files from each revision. In preparation for adding one such usage, I'm changing the API to take a list of (revision, file matcher) tuples instead. Differential Revision: https://phab.mercurial-scm.org/D8721

tests: update test-devel-warnings.t output with chg

tests: make names in test-stdio.py more distinctive This way, more tests can be added without name clashes.

tests: terminate subprocess in test-stdio.py in case of exception If an error happened while reading the output of the subprocess, the pipe / TTY buffer can fill up and prevent that the subprocess ends. Therefore we should terminate the subprocess in case of an exception.

tests: proof test-stdio.py against buffer fill-up With the previous code, it could in theory happen that the pipe / PTY buffer of the child stdout / stderr fills up and the process never finishes. To prevent that, we read all of the stream before waiting for the end of the process. To ensure that the stream reaches EOF when the child finishes, we must close the parent "copy" of the child stdout / stderr.

tests: stablize test-serve.t on Windows I forget the reason that the subprocess on Windows doesn't print this, but all other instances of this are similarly conditionalized, so I didn't think too hard about it. Also, the server needs to be killed so it doesn't prevent the next run from working, especially since the port isn't randomized. Differential Revision: https://phab.mercurial-scm.org/D8720

commitctx: document the manifest writing function Same spirit as for `_filecommit` lets document the input and output before making any change or improvement. This is part of a larger refactoring/cleanup of the commitctx code to clarify and augment the logic gathering metadata useful for copy tracing. The current code is a tad too long and entangled to make such update easy. We start with easy and small cleanup. Differential Revision: https://phab.mercurial-scm.org/D8705

commitctx: reorder some conditional for efficiency in _filecommit Checking if a dict is empty will be faster than comparing text. I don't expect it to be a huge performance win, but still a good (but gratuitous) cleanup to do while we are at it. This is part of a larger refactoring/cleanup of the commitctx code to clarify and augment the logic gathering metadata useful for copy tracing. The current code is a tad too long and entangled to make such update easy. We start with easy and small cleanup. Differential Revision: https://phab.mercurial-scm.org/D8701

commitctx: document _filecommit input and output This is the beginning of a larger refactoring/cleanup of the commitctx code to clarify and augment the logic gathering metadata useful for copy tracing. The current code is a tad too long and entangled to make such update easy. We start with easy and small cleanup. Differential Revision: https://phab.mercurial-scm.org/D8699

phases: replace magic number by constant Differential Revision: https://phab.mercurial-scm.org/D8695

clonebundles: optional memory-requirement attribution The new REQUIREDRAM option allows a client to skip bundles it isn't expected to handle well, e.g. without swapping. This allows a fallback path to be provided e.g. using zstd level 10 instead of 22. Differential Revision: https://phab.mercurial-scm.org/D8645

util: provide a helper function to estimate RAM size For POSIX systems, it uses sysconf. For Windows, it uses the win32 API directly. Differential Revision: https://phab.mercurial-scm.org/D8644

tests: allow timing difference in output Differential Revision: https://phab.mercurial-scm.org/D8676

documentation: add some internals documentation about bid merge This is an important algorithm that was only documented on the wiki so far. Some update to the algorithm (and associated doc) is to expected in the future since the bid merge algorithm is bug-ridden when it comes to file deletion comes to play. Differential Revision: https://phab.mercurial-scm.org/D8711

cmdserver: document message-encodings and channel output options While writing the previous patch, I noticed these options are undocumented. In my testing, a separate status/error message channel works well in GUI frontend as we no longer have to sort out data and message from mixed outputs. So let's mark it as not experimental.

cmdserver: add option to not exit from message loop on SIGINT Sending SIGINT to server is the only way to interrupt a command running in command-server process. SIGINT will be caught at dispatch.dispatch() if we're lucky. Otherwise it will terminate the serer process. This is fundamentally unreliable as signals are delivered asynchronously. "cmdserver.shutdown-on-interrupt=False" mitigate the issue by making the server basically block SIGINT.

pycompat: remove pycompat.{stdin,stdout,stderr} All users have been changed to use procutil.{stdin,stdout,stderr}, which provide consistent behavior across platforms and Python versions.

pycompat: change users of pycompat.{stdin,stdout,stderr} to use procutil.std* On Python 3, pycompat.{stdin,stdout,stderr} are usually block-buffered even if connected to a TTY. procutil.{stdin,stdout,stderr} provide consistent behavior across platforms and Python versions.

hgignore: add mypy cache files Differential Revision: https://phab.mercurial-scm.org/D8692

revlog: avoid hard-coded hash sizes Differential Revision: https://phab.mercurial-scm.org/D8683

test: restore expected output in test-persistent-nodemap.t The merge 78cafd48b9b2 had a small error and wrongly dropped the output updated from one side of the merge. This changeset re-install it. Differential Revision: https://phab.mercurial-scm.org/D8678

heptapod-ci: build rhg before tests run Differential Revision: https://phab.mercurial-scm.org/D8682

rhg: add a limited `rhg root` subcommand Clap has been choosen for argument parsing for the following reasons: - it's a wildly used and maintained crate - it can deal with OS encoding making it suitable for any encoding - it supports nonambiguous prefix matching as already available in hg - it will soon allow for structopts-style declarative pattern instead of the currently used builder pattern Differential Revision: https://phab.mercurial-scm.org/D8613

rhg: add RootCommand using hg-core FindRoot operation to prepare `hg root` The println macro is not used to avoid string usage. Dealing only with bytes allows us to be compatible with any encoding and not just UTF8. Later on, format macro will be made to have more readable code. Differential Revision: https://phab.mercurial-scm.org/D8612

merge with stable

procutil: make mercurial.utils.procutil.stderr unbuffered For most Mercurial code, it doesn’t make a difference, as the ui object flushes stderr explicitly (after the change, we could get rid of the explicit flush). One example where it makes a observable difference is mercurial.util.timed(). Without the patch, the time is not immediately shown on Python 3. With the patch, it’s shown immediately on all Python versions and platforms.

tests: generalize common test case code in test-stdio.py

procutil: make stdout line-buffered on Windows if connected to TTY Windows doesn’t support line buffering. Previously, we worked around that by setting the stream unbuffered. Instead, we can use our own line buffering we already use on Python 3.

procutil: split import and reassignment Besides making the code clearer, it will reduce the diff in the next patch.

procutil: move assignments closer to reassignments Doing reassignments is an anti-pattern IMHO, but I see how it makes sense here. When first looking at this code after jumping here with ctags, I missed the fact that stdout was reassigned. To make the code clearer, the assignments should be as close as possible to the reassignments.

procutil: factor out conditional creation of LineBufferedWrapper At the same time, document the logic and generalize it to work on all Python versions.

procutil: define LineBufferedWrapper on all Python versions There’s nothing Python 3-only about LineBufferedWrapper. In the future, we may want to use it on Windows, to work around missing line-buffering support.

tests: add tests for buffering behavior of mercurial.utils.procutil.stdout

cleanup: use slightly more meaningful name for temporary variable Not that it makes a big difference, but using `p` instead of `x` is clearer to me.

cleanup: use any() instead of checking truthiness of temporary list It was not immediately obvious to me, when first seeing this, why a list was created. It needed a second look to understand that the purpose was to check whether the condition is true for any of the parents. Using any() for that is clearer.

chg: suppress OSError in _restoreio() and add some logging (issue6330) According to issue6330, running chg on heavy loaded systems can lead to following error: ``` Traceback (most recent call last): File "path-to-hg/mercurial/commandserver.py", line 650, in _acceptnewconnection self._runworker(conn) File "path-to-hg/mercurial/commandserver.py", line 701, in _runworker prereposetups=[self._reposetup], File "path-to-hg/mercurial/commandserver.py", line 470, in _serverequest sv.cleanup() File "path-to-hg/mercurial/chgserver.py", line 381, in cleanup self._restoreio() File "path-to-hg/mercurial/chgserver.py", line 444, in _restoreio os.dup2(fd, fp.fileno()) OSError: [Errno 16] Device or resource busy ``` [man dup2] indicates that, on Linux, EBUSY comes from a race condition between open() and dup2(). However it's not clear why open() race occurred for newfd=stdin/out/err. We suppress the OSError in _restoreio() since the forked worker process will finish anyway and add some logging. Thanks to Mitchell Plamann for a detailed bug description and Yuya Nishihara for suggesting the fix.

ui: fix Python 2.7 support for ui.timestamp-output Differential Revision: https://phab.mercurial-scm.org/D8675

merge with stable

ui: add option to timestamp status and diagnostic messages Differential Revision: https://phab.mercurial-scm.org/D8640

merge with stable

compat: back out a25343d16ebe (initialize LC_CTYPE locale on all Python ...) As Yuya Nishihara pointed out, setting LC_CTYPE changes the behavior of some str methods on Python 2.

curses: back out d2227d4c9e6b (do not initialize LC_ALL to user settings) The changeset was based on a25343d16ebe, which will be backed out, too. Another fix for the problem will be resubmitted to the stable branch.

test: redirect stderr so warning messages don't change output (issue6237) clone and commit race for the lock, and if commit has to wait more than a second it prints a warning to stderr. Since this is somewhat expected here, silence it. Differential Revision: https://phab.mercurial-scm.org/D8664

locks: expect repo lock, not wlock, when writing to .hg/strip-backup/ There should be no need for a working copy lock when creating (or reading) bundles in `.hg/strip-backup/` since they don't affect the working copy. I noticed this because we have an extension that tries to strip some revisions while holding only a repo lock. I guess we have no such cases in core, which seems a bit surprising. Maybe we always take a wlock at a higher level so the working copy is not updated while the target commit is being stripped. Differential Revision: https://phab.mercurial-scm.org/D8666

graft: leverage cmdutil.check_incompatible_arguments() for --abort/--stop Differential Revision: https://phab.mercurial-scm.org/D8669

graft: leverage cmdutil.check_incompatible_arguments() for --no-commit Differential Revision: https://phab.mercurial-scm.org/D8668