CONTEXT(3PVM)

✨ CONTEXT(3PVM) ✨

okay bestie, gather round 🫶 we're doing CONTEXT(3PVM) from the PVM Version 3.4 manual, section 3. This is the context girlies' page: pvm_newcontext, pvm_setcontext, pvm_freecontext and pvm_getcontext. Request a new context, change your context, free an existing context, and get your current context — respectively, periodt 💅

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🌸 NAME 🌸

pvm_newcontext, pvm_setcontext, pvm_freecontext, pvm_getcontext — request new context, change context, free existing context, and get current context, respectively.

Like, four little besties, four little jobs. No cap.

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🎀 SYNOPSIS 🎀

C

int ctx = pvm_newcontext( void )
int old_ctx = pvm_setcontext( int new_ctx )
int info = pvm_freecontext( ctx )
int ctx = pvm_getcontext( void )

Fortran

call pvmfnewcontext( ctx )
call pvmfsetcontext( new_ctx, old_ctx )
call pvmffreecontext( ctx, info )
call pvmfgetcontext( ctx )

Look at those return values, they're giving very much "I have opinions about your context." ✨

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💖 PARAMETERS 💖

• ctx — Context value. that's it, that's the whole girl.
• new_ctx — New context value. the one you're switching to.
• old_ctx — Prior context value. the one you're leaving behind, like a situationship 😭
• info — Result code. she reports back.

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🦋 DESCRIPTION 🦋

So the context functions hand you a system-wide unique context plus all the tools to mess with it. And by "mess with it" I mean professionally manage it, bestie, we're not messy here 💅

Contexts are the vibe check for messages. They let communicating tasks automatically tell messages apart based on the context the message was sent in. So: a message sent in context A by the sender must be received in context A by the recipient. A sender can send in any context she wants, queen. But a recipient will not accept a message that was sent in a context different from her own. No. Ma'am. Blocked. 🚫

One big use for contexts is library routines. With contexts, library-routine inter-communication can be logically seperated from the user's application inter-communication. Which means the two of you won't accidentally open each other's mail. iconic, honestly 💌

Spawned tasks inherit the spawn-time context of their parent. And existing PVM applications just keep working, unchanged, using the default context. no migration arc required 🧚

• pvm_newcontext returns a newly allocated context. But heads up: this new context is not yet active. She exists, she's just not on stage yet, she's warming up backstage 🎭
• pvm_setcontext changes the current context from old_ctx to new_ctx.
• pvm_freecontext frees ctx so that it may be reused. And this one matters: contexts are a system resource that will be exhausted if not recycled. So recycle, bestie, the planet and the scheduler both thank you 🌍♻️
• pvm_getcontext returns the current context of the requesting task. simple. clean. she ate.

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🌈 EXAMPLES 🌈

parent task with context

/* parent task with context */
     int cc, context0, context1;
     char buf[25];

     context0 = pvm_getcontext();       /*  get my current context */
     context1 = pvm_newcontext();       /*  get a new context */
     pvm_setcontext(context1);          /*  set my context to new context */
     printf("My context is: %d", context1);
     pvm_spawn("child", (char**)0, PvmTaskDefault, "", 1, &tid);
     cc = pvm_recv(-1, -1);             /*  receive message from child - in context1 */
     pvm_upkstr(buf);
     printf("%s", buf);
     pvm_setcontext(context0);          /*  reset my context to my original context0 */

child task with context - child inherits parent's context as default

/* child task with context - child inherits parent's context as default */
     int context;
     int ptid;
     char buf[25];

     ptid = pvm_parent();
     context = pvm_getcontext();        /*  get my current context */
     sprintf(buf, "Greetings from child who's context is: %d.", context);
     pvm_initsend(PvmDataDefault);
     pvm_pkstr(buf);
     pvm_send(ptid, 1);

The child literally sends "Greetings from child who's context is: %d." — she's polite, she's concise, she knows her context number. main character energy honestly. 👑

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💀 ERRORS 💀

Only system resource errors will be returned, because the context programs themselves do not generate errors. The functions are drama-free. the rest of the system, however… 🙈

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👑 SEE ALSO 👑

ngl bestie, this section is genuinely empty of cross-references in the original — there's nothing else listed down here. Just vibes, silence, and the version stamp. 🎀

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and that's the whole page, fr fr. every flag, every parameter, every example, untouched and slaying.

okay love you, bye 💖 — this has been CONTEXT(3PVM) from PVM Version 3.4, dated 8 April, 1997. go forth and manage your contexts responsibly, bestie 🦋✨