4 ms·

I know Golang has their own implementation of sd_notify(). For Slurm, I looked at what a PITA pulling libsystemd into our autoconf tooling would be, stumbled o

I know Golang has their own implementation of sd_notify(). For Slurm, I looked at what a PITA pulling libsystemd into our autoconf tooling would be, stumbled on the Golang implementation, and realized it's trivial to implement directly.

pkaye 3y ago
Can me point me to the Golang implementation? Is it a standard package?
- yencabulator 3y ago
  Most likely https://github.com/coreos/go-systemd https://github.com/coreos/go-systemd
tripflag 3y ago
indeed; it should be trivial in any language. Here's python: https://github.com/9001/copyparty/blob/a080759a03ef5c0a6b06c697f37ae4e00812739f/copyparty/svchub.py#L1019-L1038 https://github.com/9001/copyparty/blob/a080759a03ef5c0a6b06c...
- cesarb 3y ago
  It should be trivial in any language which has AF_UNIX. Last time I looked, Java didn't have it, so the only way was to call into non-Java code.
  - reftel 3y ago
    Then I suggest you have another look =) https://inside.java/2021/02/03/jep380-unix-domain-sockets-channels/ https://inside.java/2021/02/03/jep380-unix-domain-sockets-ch...
    - fullstop 3y ago
      Under Limitations: Datagram support
      - reftel 3y ago
        It appears you are correct. What an odd limitation!
  - fullstop 3y ago
    At first I thought that this surely could not be true as of today, but it looks like it is. There is AF_UNIX support, but only for streams and not datagrams: https://bugs.openjdk.org/browse/JDK-8297837 https://bugs.openjdk.org/browse/JDK-8297837 What an odd decision. I suppose that you could execute systemd-notify but that's a solution that I would not like.
    - cesarb 3y ago
      > I suppose that you could execute systemd-notify but that's a solution that I would not like. What I did was to use JNA to call sd_notify() in libsystemd.so.0 (when that library exists), which works but obviously does not avoid using libsystemd. I suppose I could have done all the socket calls into glibc by hand, but doing that single call into libsystemd directly was simpler (and it can be expected to exist whenever systemd is being used).
    - ptx 3y ago
      It looks like the FFI (Project Panama) finally landed in Java 22, released a few days ago: https://openjdk.org/jeps/454 https://openjdk.org/jeps/454 Unless that feature also has some weird limitation, you could probably use that to call the socket API in libc.
KerrAvon 3y ago
Caveat is that golang is not a good enough actor to be a reliable indicator of whether this interface is supported, though. They’ll go to the metal because they can, not because it’s stable.

pkaye 3y ago

Can me point me to the Golang implementation? Is it a standard package?

yencabulator 3y ago
Most likely https://github.com/coreos/go-systemd https://github.com/coreos/go-systemd

tripflag 3y ago

indeed; it should be trivial in any language. Here's python: https://github.com/9001/copyparty/blob/a080759a03ef5c0a6b06c697f37ae4e00812739f/copyparty/svchub.py#L1019-L1038 https://github.com/9001/copyparty/blob/a080759a03ef5c0a6b06c...

cesarb 3y ago
It should be trivial in any language which has AF_UNIX. Last time I looked, Java didn't have it, so the only way was to call into non-Java code.
- reftel 3y ago
  Then I suggest you have another look =) https://inside.java/2021/02/03/jep380-unix-domain-sockets-channels/ https://inside.java/2021/02/03/jep380-unix-domain-sockets-ch...
  - fullstop 3y ago
    Under Limitations: Datagram support
    - reftel 3y ago
      It appears you are correct. What an odd limitation!
- fullstop 3y ago
  At first I thought that this surely could not be true as of today, but it looks like it is. There is AF_UNIX support, but only for streams and not datagrams: https://bugs.openjdk.org/browse/JDK-8297837 https://bugs.openjdk.org/browse/JDK-8297837 What an odd decision. I suppose that you could execute systemd-notify but that's a solution that I would not like.
  - cesarb 3y ago
    > I suppose that you could execute systemd-notify but that's a solution that I would not like. What I did was to use JNA to call sd_notify() in libsystemd.so.0 (when that library exists), which works but obviously does not avoid using libsystemd. I suppose I could have done all the socket calls into glibc by hand, but doing that single call into libsystemd directly was simpler (and it can be expected to exist whenever systemd is being used).
  - ptx 3y ago
    It looks like the FFI (Project Panama) finally landed in Java 22, released a few days ago: https://openjdk.org/jeps/454 https://openjdk.org/jeps/454 Unless that feature also has some weird limitation, you could probably use that to call the socket API in libc.

KerrAvon 3y ago

Caveat is that golang is not a good enough actor to be a reliable indicator of whether this interface is supported, though. They’ll go to the metal because they can, not because it’s stable.