Resource Pool Code Examples

This section contains code examples of the resource pools interface.

Ascertain the Number of CPUs in the Resource Pool

sysconf(3C) provides information about the number of CPUs on an entire system. The following example provides the granularity of ascertaining the number of CPUs that are defined in a particular application's pools pset.

The key points for this example include the following:

• pvals[] should be a NULL terminated array.

• pool_query_pool_resources() returns a list of all resources that match the pvals array type pset from the application's pool my_pool. Because a pool can have only one instance of the pset resource, each instance is always returned in nelem. reslist[] contains only one element, the pset resource.

pool_value_t *pvals[2] = {NULL};  /* pvals[] should be NULL terminated */

/* NOTE: Return value checking/error processing omitted */
/* in all examples for brevity */

conf_loc = pool_dynamic_location();
conf = pool_conf_alloc();
pool_conf_open(conf, conf_loc, PO_RDONLY);
my_pool_name = pool_get_binding(getpid());
my_pool = pool_get_pool(conf, my_pool_name);
pvals[0] = pool_value_alloc();
pvals2[2] = { NULL, NULL };
pool_value_set_name(pvals[0], "type");
pool_value_set_string(pvals[0], "pset");

reslist = pool_query_pool_resources(conf, my_pool, &nelem, pvals);
pool_value_free(pvals[0]);
pool_query_resource_components(conf, reslist[0], &nelem, NULL);
printf("pool %s: %u cpu", my_pool_ name, nelem);
pool_conf_close(conf);

List All Resource Pools

The following example lists all resource pools defined in an application's pools pset.

The key points of the example include the following:

• Open the dynamic conf file read-only, PO_RDONLY. pool_query_pools() returns the list of pools in pl and the number of pools in nelem. For each pool, call pool_get_property() to get the pool.name property from the element into the pval value.

• pool_get_property() calls pool_to_elem() to convert the libpool entity to an opaque value. pool_value_get_string() gets the string from the opaque pool value.

conf	= pool_conf_alloc();
pool_conf_open(conf, pool_dynamic_location(), PO_RDONLY);
pl = pool_query_pools(conf, &nelem, NULL);
pval = pool_value_alloc();
for (i = 0; i < nelem; i++) {
    pool_get_property(conf, pool_to_elem(conf, pl[i]), "pool.name", pval);
    pool_value_get_string(pval, &fname);
    printf("%s\n", name);
}
pool_value_free(pval);
free(pl);
pool_conf_close(conf);

Report Pool Statistics for a Given Pool

The following example reports statistics for the designated pool.

The key points for the example include the following:

• pool_query_pool_resources() gets a list of all resources in rl. Because the last argument to pool_query_pool_resources() is NULL, all resources are returned. For each resource, the name, load and size properties are read, and printed.

• The call to strdup() allocates local memory and copies the string returned by get_string(). The call to get_string() returns a pointer that is freed by the next call to get_property(). If the call to strdup() is not included, subsequent references to the string(s) could cause the application to fail with a segmentation fault.

printf("pool %s\n:" pool_name);
pool = pool_get_pool(conf, pool_name);
rl = pool_query_pool_resources(conf, pool, &nelem, NULL);
for (i = 0; i < nelem; i++) {
  pool_get_property(conf, pool_resource_to_elem(conf, rl[i]), "type", pval);
  pool_value_get_string(pval, &type);
  type = strdup(type);
  snprintf(prop_name, 32, "%s.%s", type, "name");
  pool_get_property(conf, pool_resource_to_elem(conf, rl[i]), 
        prop_name, pval);
  pool_value_get_string(val, &res_name);
  res_name = strdup(res_name);
  snprintf(prop_name, 32, "%s.%s", type, "load");
  pool_get_property(conf, pool_resource_to_elem(conf, rl[i]), 
        prop_name, pval);
  pool_value_get_uint64(val, &load);
  snprintf(prop_name, 32, "%s.%s", type, "size");
  pool_get_property(conf, pool_resource_to_elem(conf, rl[i]), 
        prop_name, pval);
  pool_value_get_uint64(val, &size);
  printf("resource %s: size %llu load %llu\n", res_name, size, load);
  free(type);
  free(res_name);
}
free(rl);

Set pool.comment Property and Add New Property

The following example sets the pool.comment property for the pset. The example also creates a new property in pool.newprop.

The key point for the example includes the following:

• In the call to pool_conf_open(), using PO_RDWR on a static configuration file, requires the caller to be root.

• To commit these changes to the pset after running this utility, issue a pooladm -c command. To have the utility commit the changes, call pool_conf_commit() with a nonzero second argument.

pool_set_comment(const char *pool_name, const char *comment)
{
  pool_t *pool;
  pool_elem_t *pool_elem;
  pool_value_t *pval = pool_value_alloc(); 
  pool_conf_t  *conf = pool_conf_alloc();
  /* NOTE: need to be root to use PO_RDWR on static configuration file */
  pool_conf_open(conf, pool_static_location(), PO_RDWR);
  pool = pool_get_pool(conf,  pool_name);
  pool_value_set_string(pval, comment);
  pool_elem = pool_to_elem(conf, pool);
  pool_put_property(conf, pool_elem, "pool.comment", pval);
  printf("pool %s: pool.comment set to %s\n:" pool_name, comment);
  /* Now, create a new property, customized to installation site */
  pool_value_set_string(pval, "New String Property");
  pool_put_property(conf, pool_elem, "pool.newprop", pval);
  pool_conf_commit(conf, 0); /* NOTE: use 0 to ensure only */
                             /* static file gets updated */
  pool_value_free(pval);
  pool_conf_close(conf);
  pool_conf_free(conf);
  /* NOTE: Use "pooladm -c" later, or pool_conf_commit(conf, 1) */
  /* above for changes to the running system */
}

An alternative way of modifying a pool's comment and adding a new pool property is to use poolcfg(1M).

poolcfg -c 'modify pool pool-name (string pool.comment = "cmt-string")'
poolcfg -c 'modify pool pool-name (string pool.newprop = 
                                   "New String Property")'