First, i know java well and i have used C++ on occasion so i thought i would be able to deal with a class where they program in C. unfortunately i have hit some speed bumps that i am having problems.
Here is my problem:
I have a structure cache_t in the sample program we are supposed to use. In one of my functions i am supposed to use a pointer to an instance of this cache_t struct to perform some operations and return a value.
How do i get the value of nsets? i have tried &cp.nsets but that just gives me an error:
error: request for member 'nsets' in something not a structure or union
---------- Post updated at 02:32 AM ---------- Previous update was at 01:10 AM ----------
ah, nevermind. As i guessed it was my inexperience with C causing problems. I was looking for cp->nsets.
Hello,
The system reboots in single user mode
what command to use to bring the system up regularly??
I get
INIT: cannot create /var/adm/utmpx
Type control -d to proceede with a normal startup
or give root passwd for system maintaince.
either way i don't have a change and ... (1 Reply)
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Todays offering - "The trouble with letting other people host your website"
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Discussion started by: kingnothing
0 Replies
LEARN ABOUT OSX
cache_remove
cache_set_and_retain(3) BSD Library Functions Manual cache_set_and_retain(3)NAME
cache_set_and_retain, cache_get_and_retain, cache_release_value, cache_remove -- Routines used to manage cached values
SYNOPSIS
#include <cache.h>
int
cache_set_and_retain(cache_t *cache, void *key, void *value, size_t cost);
int
cache_get_and_retain(cache_t *cache, void *key, void **value_out);
int
cache_release_value(cache_t *cache, void *value);
int
cache_remove(cache_t *cache, void *key);
DESCRIPTION
These routines are used to manipulate values added to an in memory cache created by cache_create(3).
cache_set_and_retain() Adds value with cost to cache and associates it with key. The caller retains a reference to value that will prevent
value from being evicted from the cache until value is released in cache_release_value().
cache_get_and_retain() Fetches value for key from cache and places value in value_out. The caller retains a reference to value that will
prevent value from being evicted from the cache until value is release in cache_release_value().
cache_release_value() Releases a reference on value back to cache so that value may be evicted. Signals that the client is not actively
using value and will use cache_get_and_retain() before using again.
cache_remove() Removes the value associated with key from cache. Note that if the value is referenced by a client, the value will not be
finalized until the reference is released using cache_release_value().
RETURN VALUES
All functions return 0 for success and non-zero for failure. The value ENOENT (see errno.h) indicates that a key or value passed as an argu-
ment does not exist in the cache. EINVAL is used for invalid arguments.
EXAMPLE
The following example attempts to fetch a value from a cache using a key. If the value is not present in the cache then it is created and
added to the cache. The value is then used and released back to the cache to allow the cache to evict it when needed.
cache_t *mycache;
cache_create("com.mycompany.mycache", &cache_attributes, &mycache);
void *mykey = my_create_key();
void *myvalue = NULL;
if (cache_get_and_retain(mycache, mykey, &myvalue) != 0) {
myvalue = my_create_value_from_key(mykey);
cache_set_and_retain(mycache, mykey, myvalue, 0);
}
my_use_value(value);
cache_release_value(mycache, myvalue);
SEE ALSO cache(3)Darwin May 7, 2009 Darwin