PHD: improve ctrl-c handling #634
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hawkw
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Install a signal handler in the PHD runner that catches SIGINT and relays it via `tokio::sync::watch` to any tasks that are currently executing tests. This allows the test tasks to exit at the next available `await` point. Since these tasks are themselves awaited before the runner exits, this ensures that all VMs and disks created by a test can be dropped and cleaned up before the runner goes away. Ctrl-C characters sent to a shell will typically cause SIGINT to be sent to all processes in the foreground process group. This is bad for PHD because any Propolis servers the runner spawned will be killed before `TestVm::drop` gets a chance to gracefully stop the VMs inside. Since dropping a `PropolisServer` kills the process in any case, get around this by configuring PHD-spawned Propolis servers to ignore SIGINT. Tested with local Debian 11 runs, observing in particular that interrupting a run with Ctrl-C does not leak any VMMs or temporary disk objects.
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(N.B. Depends on #633.)
Install a SIGINT handler in the PHD runner and use it to broadcast to all test execution tasks that this signal was received. Add a
select!to the tasks to preempt further execution of test cases when this happens. Dropping the test case futures also drops all the VMs and disks they create, giving the runner a chance to clean up kernel VMMs and disk backing files before exiting. (If one SIGINT is handled and a second is received, exit immediately to allow the runner to be killed even if a test case hasn't reached anawaitpoint.)To ensure that Propolis processes get a chance to stop gracefully, add a pre-
exechook so that the framework's Propolis servers ignore SIGINT. This is needed so that hitting Ctrl-C to interrupt a foreground runner doesn't take out the Propolis servers in the same process group beforeTestVm::dropgets a chance to clean them up.Tested with runs of Debian 11 guests, both running to completion (all tests still pass) and interrupted at various points midway (verified that kernel VMMs and disks get cleaned up as expected when they didn't before).