Add the ps command to sdb. #274
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Hey @tony-zfs thank you for opening the PR!
From what I see the failures in the test-suite are from our frozed version of mypy and the use of -h option from argparse. I have some more details on both bundled together with the rest of my feedback.
sdb/commands/linux/ps.py
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| from sdb.commands.stacks import Stacks | ||
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| def _cmdline(obj: drgn.Object) -> str: |
sdb/commands/linux/ps.py
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| return "" | ||
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| class Ps(sdb.Locator, sdb.PrettyPrinter): |
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A lot of code in this class overlaps with threads.py. Instead of duplicating code in both places did you try the following:
[1] Extend the threads command to handle the extra columns that you added (e.g. uid) and also the column logic (e.g -o , -h, etc..)
[2] Make the ps command use the threads command under the hood and keep the arguments that make it look like the linux userland ps command (e.g. -p, --ppid, etc..).
If you want an example of layering a command on top of another command checkout the spa command. It is using the avl walker for its Locator/no-input method, and vdev for its pretty-printer.
As for generic use of the Table class and how to implement the sort-by-column functionality you can look at either the slubs or spl_kmem_caches.
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Updated. Thanks for the advice.
sdb/commands/linux/ps.py
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| help="Print only the process IDs of a command") | ||
| parser.add_argument('-x', '--x', action='store_true', \ | ||
| help="Show PID, TIME, CMD") | ||
| parser.add_argument('-h', action='store_true', \ |
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Unfortunately argparse doesn't allow us to use -h for anything other than the help message. Fortunately for us looking at man ps I see that that to skip the headers only the long form argument exists --no-headers and --no-heading.
| input_type = "struct task_struct *" | ||
| output_type = "struct task_struct *" | ||
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| FIELDS: Dict[str, Callable[[drgn.Object], Union[str, int]]] = { |
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Not that it matters if we go ahead with layering the ps command on top of threads but I don't see task mentioned here. What if a user wants to specify it with the -o option?
sdb/commands/linux/ps.py
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| help="Show the output without headers.") | ||
| parser.add_argument('-p', '--p', type=str, \ | ||
| help="Select by process ID. Identical to --pid.") | ||
| parser.add_argument('-ppid', '--ppid', type=str, \ |
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Having the long-form and the short-form argument look the same doesn't look right. Looking at man ps it seems like only the long-form is supported --ppid. If you really want a short-form I don't think -P is taken, so we could use that.
In addition, like -p/--pid the type of argument can be a list of integers.
sdb/commands/linux/ps.py
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| help="Show PID, TIME, CMD") | ||
| parser.add_argument('-h', action='store_true', \ | ||
| help="Show the output without headers.") | ||
| parser.add_argument('-p', '--p', type=str, \ |
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Looking at man ps I think the correct long-form for this is --pid.
sdb/commands/linux/ps.py
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| pids = [int(x) for x in self.args.p.split(',')] if self.args.p else [] | ||
| ppids = [int(x) for x in self.args.ppid.split(',') |
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what happens here when we get faulty input? (e.g. "asdf, asdfasdf")
If the result is that we blow up maybe it may be easier to switch from the ps --pid 1,2,3 to ps --pid 1 2 3 notation (both are supported from the userland ps utility in Linux from what I can tell). This would mean that we'd need to change the argument type to something like type=int, nargs="+",.
| "ps", | ||
| "ps -C bash", | ||
| "ps -p 4275", | ||
| "ps -e", | ||
| "ps -x", | ||
| "ps -o pid,ppid", | ||
| "ps -A", |
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Thanks for extending the test-suite!
sdb/commands/stacks.py
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| @classmethod | ||
| def _init_parser(cls, name: str) -> argparse.ArgumentParser: | ||
| def _init_parser(cls, name: str) -> argparse.ArgumentParser(): |
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Pressumably mypy bothered you about this change. We've found it to be extremely inconsistent with false-positives being introduced at every new release thus we've frozed our version of mypy in our Github Actions to 0.730 - https://github.com/delphix/sdb/blob/master/.github/workflows/main.yml#L100 . You may want to do the same in your python environment for sdb locally.
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I would love to see sample output of the new subcommand as part of the PR. |
tony-zfs
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Updated. Is there anything else needed to get this to be accepted? |
If you drill into the commit, there are sample outputs used in the automated testing of the new command. Look for |
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Issue Number: 248
#248
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