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