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cfg_psm_memops(3)
Contents
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cfg_psm_memops, cfg_psm_memadd, cfg_psm_memrem,
cfg_psm_memget - Perform member operations on the Process
Set manager (PSM) set
Library: configuration management library, libcfg.a.
#include <cfg.h>
cfg_status_t cfg_psm_memadd(
const char *node,
const char *catnam,
pid_t pid ); cfg_status_t cfg_psm_memrem(
const char *node,
const char *catnam,
pid_t pid ); cfg_status_t cfg_psm_memget(
const char *node,
const char *catnam,
pid_t pid,
psm_memrsp_t **memrsp ); void cfg_psm_memfree(
psm_memrsp_t **memrsp );
Refer to PSM(4) for a description of the Process Set Manager,
which supports the functions described in this reference
page.
Functions [Toc] [Back]
Use these functions as follows: Adds a process instance
defined by the value of pid in the catnam category to the
process set on the host defined by the value of host node.
Removes the process instance defined by the value of pid
in the catnam category from the process set on the host
defined by the value of host node. Retrieves the process
instance information from the process Sset on host node.
The following conditions apply: If the value of pid is not
_PSM_ALLPID, information on a specific process is
returned. Specify the catnam to ensure a process is in a
specific category, or specify _PSM_ALLCAT if this check is
not wanted. If the value of pid is _PSM_ALLPID and the
value of catnam is not _PSM_ALLCAT, all instances for a
specific category are returned. If the value of pid is
_PSM_ALLPID and the value of catnam is _PSM_ALLCAT, all
instances in all categories are returned. When the
response is complete, you must free memory using
cfg_psm_memfree(). Frees the memrsp array allocated by
cfg_psm_memget().
Operation and Usage Instructions [Toc] [Back]
Upon successful completion of the cfg_psm_memget() function,
the memrsp parameter points to an array of one or
more struct psm_memrsp_s elements. These elements are
declared in the psm.h header file and are duplicated
below. Each element represents a specific process
instance. In case of an error, the parameter memrsp is set
to NULL:
typedef struct psm_memrsp_s {
unsigned int mrs_listidx; /* member number in list
*/
unsigned int mrs_listcnt; /* total members in list
*/
unsigned int mrs_total; /* total matching
members */
unsigned int mrs_pid; /* process id */
unsigned int mrs_exitcode; /* exit status code */
unsigned int mrs_flags; /* process flags
(PSM_FL_*) */
char mrs_name[PSM_MEMLEN]; /* unique name of member
*/
char mrs_state[PSM_STATELEN]; /* state ("running",
etc.) */
char mrs_argv[PSM_ARGVLEN]; /* saved argv */
} psm_memrsp_t;
These elements are defined as follows: mrs_listidx holds
the index (starting at 1) of an instance entry in the
array. mrs_listcnt and mrs_total hold the total number of
instances. Both values will always be the same when you
use the cfg_psm_memget() function. mrs_pid is the process
identifier (PID) associated with the instance. mrs_exitcode
holds the termination status if the process has
exited. This element is suitable for use with the wait
status macros. See wait(2). mrs_name is a cluster-wide
unique name of the form node-id-process-id. mrs_state is
a user-modifiable string containing useful state information.
mrs_argv contains the process argument vector
obtained from address space when cfg_psm_memadd() is
invoked. mrs_flags are bit flags, described as follows:
PSM_FL_EXIT is set if the process has exited.
PSM_FL_ARGTRUNC is set if mrs_argv was truncated.
In case of a generic query and no instances are registered,
an array of one element is returned with all fields
set to 0.
Processes can self-register with the PSM using the
_PSM_CAT_* indices and the _PSM_REGSELF(idx) macro defined
in the cfg.h header file. See the EXAMPLES section for a
usage example. However, the following caveats apply: Take
care when placing the _PSM_REGSELF() macro in existing
services. Some processes call fork, after which, the parent
process exits and the child process persists. In such
cases, insert the _PSM_REGSELF() macro in the child code
for the child process. After initialization, some processes
modify their argument vector. If you do not nsert
the _PSM_REGSELF() macro before this event occurs the
saved argument vector will be useless.
The node should be specified as _PSM_MYNODE when operating
on the process set of the local host, otherwise it can
contain the name of a target host. Future implementations
will permit _PSM_ALLNODE to gather cluster-wide information,
or information from a comma-separated list of host
names. A successful response from any node guarantees a
CFG_SUCCESS return to the caller (errors from the other
nodes are ignored). In the present implementation,
multinode queries return an ENOTSUP subsystem error.
Upon successful completion, the cfg_psm_memadd(),
cfg_psm_memrem(), and cfg_psm_memget() functions return
CFG_SUCCESS. Other return values indicate that an error
has occurred. For information about handling return values
from routines in the configuration management library,
refer to libcfg(3).
The following subsystem errors might be merged with a
CFG_FRAME_SUCCESS response: The specified instance pid was
found to exist in a category during an add operation. The
process is being created or doing exec during a proxy-add
operation. There was a general KSM failure during an add
operation. The PSM process set is not registered with
KSM. The category or pid was not found. User or kernel
memory allocation failed. The maximum number of instances
is exceeded during an add operation. This operation is
not yet implemented. The instance pid could not be found
in process table during an add operation.
The following example registers a process in the mountd
category on the local host:
#include <cfg.h>
_PSM_REGSELF(_PSM_CAT_MOUNTD);
In this example, a proxy is registering process id
123 into the abcd category on remote host zeus:
cfg_status_t retval;
if ((retval = cfg_psm_memadd("zeus", "abcd",
123)) != CFG_SUCCESS) print_error(retval);
The following example retrieves all instances in
the mountd category on the local host and determines
how many are still running.
#include <cfg.h>
#include <stdio.h>
struct psm_memrsp_s *memrsp, *msp, *msp_e;
cfg_status_t retval;
const char *catnam = "mountd";
int runcount = 0;
retval = cfg_psm_memget(_PSM_MYNODE, catnam,
_PSM_ALLPID, &memrsp);
if (retval != CFG_SUCCESS) {
print_error(retval);
} else { msp = memrsp; msp_e =
memrsp + msp->mrs_listcnt; while (msp <
msp_e) { if ((msp->mrs_flags &
PSM_FL_EXIT) == 0) runcount++;
msp++; } cfg_psm_memfree(memrsp);
printf("running %d instance(s) of %s\n",
runcount, catnam);
}
Functions: fork(2), libcfg(3), cfg_psm_catops(3) wait(2)
Files: PSM(4)
cfg_psm_memops(3)
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