INITSEND(3PVM)

💌 INITSEND(3PVM) — the pvm_initsend glow-up

okay bestie, welcome to INITSEND(3PVM) from the PVM Version 3.4 manual — this is the page that tells you how to wipe your send buffer clean and pick how your message is gonna get encoded. it's giving fresh-start energy. let's go 💅

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✨ NAME ✨

pvm_initsend — clears the default send buffer and tells PVM how to encode your message.

like, it's the reset button before you pack a whole new vibe into a message 🎀

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🌸 SYNOPSIS 🌸

C:

int bufid = pvm_initsend( int encoding )

Fortran:

call pvmfinitsend( encoding, bufid )

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🦋 PARAMETERS 🦋

• encoding — an integer that says which encoding scheme the next message is gonna use. In C your options are:
  • PvmDataDefault — 0 — XDR
  • PvmDataRaw — 1 — no encoding
  • PvmDataInPlace — 2 — data left in place

and in Fortran the option names go by:

• PVMDEFAULT — 0 — XDR
• PVMRAW — 1 — no encoding
• PVMINPLACE — 2 — data left in place

• bufid — the integer that comes back holding your message buffer identifier. if it's less than zero, bestie, that means an error happened 😭

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💖 DESCRIPTION 💖

so pvm_initsend literally clears the send buffer and gets it ready for packing up a brand new message. the encoding scheme you're gonna pack with? that's set by encoding. 🫶

XDR encoding is the default, and here's why: PVM has no idea whether you're about to add a heterogeneous machine into the mix before this message actually gets sent. it can't read your mind, queen. but if you know the next message is only ever going to a machine that understands the native format, you can use PvmDataRaw encoding and save on those encoding costs. ate. ✨

PvmDataInPlace encoding says: leave the data in place while packing. the message buffer only holds the sizes and pointers to the items being sent. then when pvm_send gets called, the items are copied directly out of your memory. this option cuts down the number of times a message gets copied, but the trade-off is real — you're not allowed to modify the items between the moment they're packed and the moment they're sent. so like, hands off, okay? 🙈

if pvm_initsend succeeds, bufid will contain the message buffer identifier. if some error occurs, then bufid will be < 0. no cap.

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🚫 RESTRICTIONS 🚫

listen up, because this one matters: PvmDataInPlace allows only dense (stride = 1) data in version 3.3. it cannot be used on shared memory (*MP) architectures — a PvmNotImpl error will occur at send time. so if you're on *MP, that's a hard no, babes. 💀

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🌈 EXAMPLES 🌈

C:

bufid = pvm_initsend( PvmDataDefault );
info = pvm_pkint( array, 10, 1 );
msgtag = 3 ;
info = pvm_send( tid, msgtag );

Fortran:

CALL PVMFINITSEND(PVMRAW, BUFID)
CALL PVMFPACK( REAL4, DATA, 100, 1, INFO )
CALL PVMFSEND( TID, 3, INFO )

look at that. iconic. 👑

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😭 ERRORS 😭

these error conditions can be returned by pvm_initsend:

• PvmBadParam — you gave an invalid encoding value. wrong vibe, try again 🙈
• PvmNoMem — Malloc has failed. there is not enough memory to create the buffer. tragic. truly.

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👀 SEE ALSO 👀

• pvm_mkbuf(3PVM)

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and that's the whole page, bestie!! this was INITSEND(3PVM) from PVM Version 3.4, dated 30 August, 1993 — yes she's an elder but she still slays 💜 go clear that buffer and pack something beautiful. mwah! 💖✨