oracular (3) __pmUnparseHostSpec.3.gz

NAME

       __pmParseHostSpec, __pmUnparseHostSpec, __pmFreeHostSpec - uniform host specification parser

C SYNOPSIS

       #include "pmapi.h"
       #include "libpcp.h"

       int __pmParseHostSpec(const char *string, __pmHostSpec **hostsp, int *count, char **errmsg);
       int __pmUnparseHostSpec(__pmHostSpec *hosts, int count, char *string, size_t size);
       void __pmFreeHostSpec(__pmHostSpec *hosts, int count);

       cc ... -lpcp

CAVEAT

       This documentation is intended for internal Performance Co-Pilot (PCP) developer use.

       These  interfaces  are  not part of the PCP APIs that are guaranteed to remain fixed across releases, and
       they may not work, or may provide different semantics at some point in the future.

DESCRIPTION

       __pmParseHostSpec accepts a string specifying the location of a PCP performance metric collector  daemon.
       The  syntax  of the various formats of this string is described in PCPIntro(1) where several examples are
       also presented.

       The syntax allows the initial pmcd(1) hostname to be optionally followed by a list of port numbers, which
       will  be tried in order when connecting to pmcd on that host.  The list of port numbers is separated from
       the hostname using a colon, and each port in the list is comma-separated.

       In addition, one or more optional pmproxy(1) hosts can be specified (currently, only one  proxy  host  is
       supported  by  the PCP protocols).  These are separated from each other and from the pmcd component using
       the @ character.  These may also be followed by an optional port list,  using  the  same  comma-separated
       syntax as before.

       __pmParseHostSpec  takes a null-terminated host specification string and returns an array of __pmHostSpec
       structures, where the array has count entries.

       These __pmHostSpec structures that are  returned  via  hostsp  represent  each  individual  host  in  the
       specification string and has the following declaration:

           typedef struct {
               char    *name;       /* hostname (always valid) */
               int     *ports;      /* array of host port numbers */
               int     nports;      /* number of ports in host port array */
           } __pmHostSpec;

       __pmUnparseHostSpec  performs  the  inverse  operation, creating a string representation from a number of
       hosts structures.  Where the count of structures indicated by hosts is greater than one, the proxy syntax
       is used to indicate a chain of proxied hosts.  The size of the supplied string buffer must be provided by
       the caller using the size parameter.

RETURN VALUE

       If the given string is successfully parsed __pmParseHostSpec returns zero.   In  this  case  the  dynamic
       storage  allocated  by  __pmParseHostSpec  can  be released by calling __pmFreeHostSpec using the address
       returned from __pmParseHostSpec via hosts.

       __pmParseHostSpec returns PM_ERR_GENERIC and a dynamically allocated error message string in  errmsg,  if
       the  given  string  does not parse, and the user-supplied errmsg pointer is non-null.  Be sure to free(3)
       the error message string in this situation.

       In the case of an error, hosts is undefined.  In the case of success, errmsg is undefined.

       On success __pmUnparseHostSpec returns a positive value indicating the number of characters written  into
       the  supplied buffer.  However, if the supplied buffer was too small, a negative status code of -E2BIG is
       returned.

SEE ALSO

       pmcd(1), pmproxy(1), pmchart(1), __pmParseHostAttrsSpec(3), PMAPI(3) and pmNewContext(3).