__pmUnparseHostSpec(3) — Linux manual page


PMPARSEHOSTSPEC(3)        Library Functions Manual        PMPARSEHOSTSPEC(3)

NAME         top

       __pmParseHostSpec,  __pmUnparseHostSpec,  __pmFreeHostSpec  - uniform
       host specification parser

C SYNOPSIS         top

       #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         top

       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         top

       __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 portlist 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

RETURN VALUE         top

       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         top

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

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
       Information about the project can be found at ⟨http://www.pcp.io/⟩.
       If you have a bug report for this manual page, send it to
       pcp@groups.io.  This page was obtained from the project's upstream
       Git repository ⟨https://github.com/performancecopilot/pcp.git⟩ on
       2020-08-13.  (At that time, the date of the most recent commit that
       was found in the repository was 2020-08-11.)  If you discover any
       rendering problems in this HTML version of the page, or you believe
       there is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

Performance Co-Pilot                 PCP                  PMPARSEHOSTSPEC(3)