HOSTSYNC(3PVM)

💖 HOSTSYNC — ok bestie, let's get the time from a PVM host 💖

So this is pvm_hostsync, living its best life in the PVM Version 3.4 manual section 3PVM. It's giving "what time is it over there, actually" energy. 🕐✨

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✨ NAME ✨

pvm_hostsync — grab the time-of-day clock from a PVM host. That's it, that's the whole job. 🎀

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🌸 SYNOPSIS 🌸

C girlies, hit it:

#include <sys/time.h>
int info = pvm_hostsync( int host, struct timeval *clk,
     struct timeval *delta )

Fortran besties, this one's yours:

call pvmfhostsync( host, clksec, clkusec, deltasec, deltausec, info )

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🦋 PARAMETERS 🦋

• host — the TID of the host. Like, which host are we clocking, bestie? 👑
• clk (or, in Fortran land, clksec and clkusec) — this one hands you back a time-of-day clock sample straight from the host. 🕰️
• delta (or deltasec and deltausec) — this bad boy returns the difference between your local clock and the remote host's clock. It's giving "how out of sync are we, fr fr". 😭

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💅 DESCRIPTION 💅

Okay so pvm_hostsync samples the time-of-day clock of a host inside the virtual machine, and it gives you both the clock value and the difference between the local and remote clocks. Two for one, no cap. 🫶

Now here's the cute part: to keep the delta error down (because, like, message transit time is real and it's a hater), local clock samples get taken before and after reading the remote clock. The delta is then the difference between the mean of those local clocks and the remote clock. Obsessed with the precision tbh. ⭐

Heads up bestie: the delta time can absolutely be negative. Don't panic. The microseconds field is always normalized to 0..999999, and the sign of the seconds field is what tells you the sign of the delta. Iconic little system. For example:

3.25 Sec =  3,250000
0        =  0,0
-1 uSec  = -1,999999
-1 Sec   = -1,000000
-1.1 Sec = -2,999000

And in C specifically: if clk or delta is a null pointer, that parameter just... doesn't get returned. Skipped. Not invited to the party. 🙈

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😭 ERRORS 😭

If pvm_hostsync slays, it returns PvmOk. 💚 But these error conditions can come back at you instead:

• PvmSysErr — pvmd not responding. It's ghosting you, literally. 💀
• PvmNoHost — the specified host is not in the virtual machine. Not in the group chat, not in the VM. 🚫
• PvmHostFail — the host is unreachable, which means it possibly failed. Big yikes. 🔥

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🌈 SEE ALSO 🌈

• pvm_config(3PVM) — go read that one too, bestie, iykyk. 💜

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Okay that's the whole page! This lil masterpiece comes from PVM Version 3.4, dated 20 February, 1994 — yes she's vintage, yes she still ate. Periodt. 🎀✨