GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 2.1AS(Slurm) |
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pvmfsetcontext(3) |
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pvm_newcontext
− Request new context.
pvm_setcontext − Change context.
pvm_freecontext − Free existing context.
pvm_getcontext − Get current context.
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C |
int ctx = pvm_newcontext( void ) | ||
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int old_ctx = pvm_setcontext( int new_ctx ) | |||
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int info = pvm_freecontext( ctx ) | |||
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int ctx = pvm_getcontext( void ) |
Fortran
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call pvmfnewcontext( ctx ) | |
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call pvmfsetcontext( new_ctx, old_ctx ) | |
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call pvmffreecontext( ctx, info ) | |
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call pvmfgetcontext( ctx ) |
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ctx |
Context value. |
new_ctx
New context value.
old_ctx
Prior context value.
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info |
Result code. |
The context functions provide a system-wide unique context and the means to manipulate this context.
Contexts provide the ability for communicating tasks to automatically differentiate messages by the context in which they were sent. Thus a message sent in context A by the sender must be received in context A by the recipient. A sender may send in any context. However, a recipient will not accept a message sent in a context that differs from its own.
One such use of contexts is with library routines. Using contexts, library routine inter-communication may be logically seperated from the user’s application inter-communication. This will prevent the inadvertent receipt of one another’s messages.
Spawned tasks inherit the spawn-time context of their parent. Existing PVM applications work unchanged using the default context.
pvm_newcontext returns a newly allocated context. However, this new context is not yet active.
pvm_setcontext changes the current context from old_ctx to new_ctx.
pvm_freecontext frees ctx so that it may be reused. Contexts are a system resource that will be exhausted if not recycled.
pvm_getcontext returns the current context of the requesting task.
/* parent task with context */
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int cc, context0, context1; |
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char buf[25]; |
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context0 = pvm_getcontext(); |
/* get my current context */ | |||||
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context1 = pvm_newcontext(); |
/* get a new context */ | |||||
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pvm_setcontext(context1); |
/* set my context to new context */ | |||||
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printf("My context is: %d", context1); |
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pvm_spawn("child", (char**)0, PvmTaskDefault, "", 1, &tid); |
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cc = pvm_recv(-1, -1); |
/* receive message from child - in context1 */ | |||||
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pvm_upkstr(buf); |
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printf("%s", buf); |
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pvm_setcontext(context0); |
/* reset my context to my original context0 */ |
/* child task with context - child inherits parent’s context as default */
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int context; |
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int ptid; |
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char buf[25]; |
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ptid = pvm_parent(); |
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context = pvm_getcontext(); |
/* get my current context */ | ||||
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sprintf(buf, "Greetings from child who’s context is: %d.", context); |
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pvm_initsend(PvmDataDefault); |
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pvm_pkstr(buf); |
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pvm_send(ptid, 1); |
Only system resource errors will be returned as the context programs themselves do not generate errors.
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pvmfsetcontext(3) | |