hgweb: profile HTTP requests Currently, running `hg serve --profile` doesn't yield anything useful: when the process is terminated the profiling output displays results from the main thread, which typically spends most of its time in select.select(). Furthermore, it has no meaningful results from mercurial.* modules because the threads serving HTTP requests don't actually get profiled. This patch teaches the hgweb wsgi applications to profile individual requests. If profiling is enabled, the profiler kicks in after HTTP/WSGI environment processing but before Mercurial's main request processing. The profile results are printed to the configured profiling output. If running `hg serve` from a shell, they will be printed to stderr, just before the HTTP request line is logged. If profiling to a file, we only write a single profile to the file because the file is not opened in append mode. We could add support for appending to files in a future patch if someone wants it. Per request profiling doesn't work with the statprof profiler because internally that profiler collects samples from the thread that *initially* requested profiling be enabled. I have plans to address this by vendoring Facebook's customized statprof and then improving it.

hgweb: abstract call to hgwebdir wsgi function The function names and behavior now matches hgweb. The reason for this will be obvious in the next patch.

profiling: don't error with statprof when profiling has already started statprof.reset() asserts if profiling has already started. So don't call if it profiling is already running.

profiling: add a context manager that no-ops if profiling isn't enabled And refactor dispatch.py to use it. As you can see, the resulting code is much simpler. I was tempted to inline _runcommand as part of writing this series. However, a number of extensions wrap _runcommand. So keeping it around is necessary (extensions can't easily wrap runcommand because it calls hooks before and after command execution).

profiling: make profiling functions context managers (API) This makes profiling more flexible since we can now call multiple functions when a profiler is active. But the real reason for this is to enable a future consumer to profile a function that returns a generator. We can't do this from the profiling function itself because functions can either be generators or have return values: they can't be both. So therefore it isn't possible to have a generic profiling function that can both consume and re-emit a generator and return a value.

dispatch: set profiling.enabled when profiling is enabled We do this for other global command arguments. We don't for --profile for reasons that are unknown to me. Probably because nobody has needed it. An upcoming patch will introduce a new consumer of the profiling code. It doesn't have access to command line arguments. So let's set the config option during argument processing. We also remove a check for "options['profile']" because it is now redundant.

profiling: move profiling code from dispatch.py (API) Currently, profiling code lives in dispatch.py, which is a low-level module centered around command dispatch. Furthermore, dispatch.py imports a lot of other modules, meaning that importing dispatch.py to get at profiling functionality would often result in a module import cycle. Profiling is a generic activity. It shouldn't be limited to command dispatch. This patch moves profiling code from dispatch.py to the new profiling.py. The low-level "run a profiler against a function" functions have been moved verbatim. The code for determining how to invoke the profiler has been extracted to its own function. I decided to create a new module rather than stick this code elsewhere (such as util.py) because util.py is already quite large. And, I foresee this file growing larger once Facebook's profiling enhancements get added to it.

merge with stable

pycompat: avoid using an extra function We have a single line function which just lowercase the letters and replaces "_" with "". Its better to avoid that function call. Moreover we calling this function around 33 times.

pycompat: remove multiple occurences of urlencode By mistake we had two occurences of urlencode.

osx: stamp the hg version into the version field in the pkg This is required for tools like https://github.com/munki/munki, and is also more semantically correct.

performance: disable workaround for an old bug of Python gc Since disabling the gc does things worse for pypy and the bug was fixed in 2.7, let's only enable it in <2.7

merge: always use other, not remote, in user prompts Now that we store and display merge labels in user prompts (not just conflict markets), we should rely on labels to clarify the two sides of a merge operation (hg merge, hg update, hg rebase etc). "remote" is not a great name here, as it conflates "remote" as in "remote server" with "remote" as in "the side of the merge that's further away". In cases where you're merging the "wrong way" around, remote can even be the "local" commit that you're merging with something pulled from the remote server.

merge: use labels in prompts to the user Now that we persist the labels, we can consistently use the labels in prompts for the user without risk of confusion. This changes a huge amount of command output: This means that merge prompts like: no tool found to merge a keep (l)ocal, take (o)ther, or leave (u)nresolved? u and remote changed a which local deleted use (c)hanged version, leave (d)eleted, or leave (u)nresolved? c become: no tool found to merge a keep (l)ocal [working copy], take (o)ther [destination], or leave (u)nresolved? u and remote [source] changed a which local [dest] deleted use (c)hanged version, leave (d)eleted, or leave (u)nresolved? c where "working copy" and "destination" were supplied by the command that requested the merge as labels for conflict markers, and thus should be human-friendly.

journal: use the dirstate parentchange callbacks Instead of hacking into dirstate internals let's use the callbacks to be notified about wd parent change.

dirstate: add callback to notify extensions about wd parent change The journal extension had to touch the dirstate internals to be notified about wd parent change. To make that detection cleaner and reusable let's move it core. Now the extension can register to be notified about parent changes.

revpair: do not optimize tree to check for odd-range spec At cc3a30ff9490, we had to optimize a parsed tree to resolve x^:y ambiguity. Since we've moved the resolution of x^:y to parse(), we no longer have to call optimize(). Therefore, (x:y) can be taken as a single expression, not an odd range expression x:y.

revset: also parse x^: as (x^): Given x^:y is (x^):y, this seems sensible.

revset: resolve ambiguity of x^:y before alias expansion This is purely a parsing problem, which should be resolved before alias expansion.

revset: add test for resolution of infix/suffix ambiguity of x^:y This is the test for 805651777188, and I'm going to fix the failure of 'x^A' where 'revsetalias.A=:y'.

parser: remove unused binding parameter from suffix action Because a suffix action never takes subsequent tokens, it should have no binding strength nor closing character. I've tried if this value could be used to resolve infix/suffix ambiguity of x^:y, but it appears not. So I decided to resend this patch.

revset: fix keyword arguments to go through optimization process Before, a keyvalue node was processed by the last catch-all condition of _optimize(). Therefore, topo.firstbranch=expr would bypass tree rewriting and would crash if an expr wasn't trivial.

extensions: add unwrapfunction to undo wrapfunction Before this patch, we don't have a safe way to undo a wrapfunction because other extensions may wrap the same function and calling setattr will undo them accidentally. This patch adds an "unwrapfunction" to address the issue. It removes the wrapper from the wrapper chain, and re-wraps everything, which is not the most efficient but short and easy to understand. We can revisit the code if we have perf issues with long chains. The "undo" feature is useful in cases like wrapping a function just in a scope. Like, having a "select" command to interactively (using arrow keys) select content from some output (ex. smartlog). It could wrap "ui.label" to extract interesting texts just in the "select" command.

extensions: add getwrapperchain to get a list of wrappers The getwrapperchain returns a list of wrappers + the original function, making it easier to understand what has been wrapped by whom. For example: In : mercurial.extensions.getwrapperchain(mercurial.dispatch, '_runcommand') Out: [<function hgext.pager.pagecmd>, <function hgext.color.colorcmd>, <function hgext.zeroconf.cleanupafterdispatch>, <function mercurial.dispatch._runcommand>] It will also be useful to safely unwrap a function. See the next patch.

extensions: set attributes to wrappers so we can trace them back This patch adds two attributes about the original function and the unbound wrapper. It allows us to get a chain of wrappers. See the next patch.

ui: drop values returned by inspect.*frame*() to avoid cycles "f = inspect.currentframe()" instantly creates a cycle because "f.f_locals['f']" is "f" itself. This patch explicitly sets those frame objects to None to avoid cycles.

dispatch: split global error handling out so it can be reused We may want a similar error handling at worker.py. This patch extracts the error handling logic to "callcatch" so it can be reused.

py3: conditionalize _winreg import _winreg module is renamed to winreg in python 3. Added the conditionalize statements in the respective file because adding this in pycompat will result in pycompat throwing error as this is a windows registry module and we have buildbots and most of the contributors on linux.