match: make exactmatcher.visitchildrenset return file children as well Previously, if we had an exactmatcher like ['foo.txt', 'a/bar.txt', 'a/b/c/baz.txt'], we'd get back the following data: '.': {'a'} 'a': {'b'} 'a/b': {'c'} 'a/b/c': 'this' 'a/b/c/d': set() This was incorrect, since visitchildrenset explicitly says not to pay attention to 'foo.txt' and 'a/bar.txt' by not returning them or 'this'. Given the near impossibility of making visitchildrenset reliabbly produce only subdirectories, a previous commit has made it documented and expected that visitchildrenset can return a set containing both files and subdirectories to visit, instead of implying/requiring that visitchildrenset() return 'this' if there are files to visit. This makes the code for exactmatcher match this clarified documentation. Differential Revision: https://phab.mercurial-scm.org/D4365

match: document that visitchildrenset might return files At least when using includematcher, and probably most matchers, we do not know if a/b/f refers to a file 'f' in a/b, or a subdirectory 'f' in a/b, so most matchers will return {'f'} for visitchildrenset('a/b'). Arguably, all matchers could/should - for exactmatcher, we know that 'f' is a file, but there's no reason to return 'this' for visitchildrenset('a/b') causing code to investigate 'a/b/x', for example. Differential Revision: https://phab.mercurial-scm.org/D4364

util: make timedcm require the label (API) Differential Revision: https://phab.mercurial-scm.org/D4350

cleanup: make all uses of timedcm specify what they're timing It's not used in the timing itself, but it's valuable for the trace events we emit. Differential Revision: https://phab.mercurial-scm.org/D4349

util: make timedcm context manager also emit trace events Differential Revision: https://phab.mercurial-scm.org/D4348

demandimport: instrument python 2 code with trace events This causes the evaluation of an import in Python 3 to emit some trace data. There's some interesting wrinkles in here, like the fact that before we even hit dispatch we've demand-imported `sys` several times, despite the fact that `sys` was already fully loaded as one of the first few statements in the `hg` script. I don't think that's actually costing us a ton of performance, but it's probably something we should investigate fixing some day. Differential Revision: https://phab.mercurial-scm.org/D4347

dispatch: have dispatch.dispatch and dispatch._runcatch emit trace events Differential Revision: https://phab.mercurial-scm.org/D4345

tracing: new module to make tracing events in hg easier This lives in hgdemandimport because I want to instrument a bunch of low-level stuff including the bare `hg` script and demandimport, so it can't live at a higher layer. Differential Revision: https://phab.mercurial-scm.org/D4344

tests: add support for emitting trace events to run-tests Right now this is pretty basic, but it's a start. Differential Revision: https://phab.mercurial-scm.org/D4343

contrib: new script to read events from a named pipe and emit catapult traces I'm starting to get more serious about getting some insight into where we're spending our time, both in hg itself but also in the test suite. As a first pass, I'm going to try and produce catapult traces[0] that can be viewed with Chrome's `about:tracing` tool. 0: https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU/edit#heading=h.nso4gcezn7n1 Differential Revision: https://phab.mercurial-scm.org/D4342