showstack: also handle SIGALRM This is looking *very* handy when debugging mysterious hangs in a test: you can wrap a hanging invocation in `perl -e 'alarm shift @ARGV; exec @ARGV' 1` for example, a hanging `hg pull` becomes `perl -e 'alarm shift @ARGV; exec @ARGV' 1 hg pull` where the `1` is the timeout in seconds before the process will be hit with SIGALRM. After making that edit to the test file, you can then use --extra-config-opt on run-tests.py to globaly enable showstack during the test run, so you'll get full stack traces as you force your hg to exit. I wonder (but only a little, not enough to take action just yet) if we should wire up some scaffolding in run-tests itself to automatically wrap all commands in alarm(3) somehow to avoid hangs in the future? Differential Revision: https://phab.mercurial-scm.org/D4870

exchangev2: add progress bar around manifest scanning This can take a long time on large repositories. Let's add a progress bar so we don't have long periods where it isn't obvious what is going on. Differential Revision: https://phab.mercurial-scm.org/D4859

httppeer: report http statistics Now that keepalive.py records HTTP request count and the number of bytes sent and received as part of performing those requests, we can easily print a report on the activity when closing a peer instance! Exact byte counts are globbed in tests because they are influenced by non-deterministic things, such as hostnames and port numbers. Plus, the exact byte count isn't too important anyway. I feel obliged to note that printing the byte count could have security implications. e.g. if sending a password via HTTP basic auth, the length of that password will influence the byte count and the reporting of the byte count could be a side-channel leak of the password length. I /think/ this is beyond our threshold for concern. But if we think it poses a problem, we can teach the byte count logging code to e.g. ignore sensitive HTTP request headers. We could also consider not reporting the byte count of request headers altogether. But since the wire protocol uses HTTP headers for sending command arguments, it is kind of important to report their size. Differential Revision: https://phab.mercurial-scm.org/D4858

keepalive: track number of bytes received from an HTTP response We also bubble the byte count up to the HTTPConnection instance and its parent opener at read time. Unlike sending, there isn't a clear "end of response" signal we can intercept to defer updating the accounting. Differential Revision: https://phab.mercurial-scm.org/D4857