Provided by: libpcp3-dev_3.10.8build1_amd64 bug


       pmDiscoverServices - discover PCP services on the network


       #include <pcp/pmapi.h>

       int pmDiscoverServices(const char *service, const char *mechanism, char ***urls);

       #include <pcp/impl.h>

       int __pmDiscoverServicesWithOptions(const char *service, const char *mechanism, const char *optionsString, const volatile unsigned *flags, char ***urls);

       cc ... -lpcp


       Given  a  PCP  service  name,  as  identified  by service, and using the type of discovery
       optionally specified in mechanism, pmDiscoverServices returns, via urls, a  list  of  URLs
       representing the services discovered on the network.

       The  internal function __pmDiscoverServicesWithOptions performs the same function and adds
       arguments for global options and a mechanism for interrupting the discovery process.

       The pmfind(1) utility provides command line access to both of these interfaces.


       pmDiscoverServices(service, mechanism, urls)

       is equivalent to calling

       __pmDiscoverServicesWithOptions(service, mechanism, NULL, NULL, urls);

       service specifies the PCP service to  be  discovered.  Currently  supported  services  are
       pmcd(1), pmproxy(1), and pmwebd(1), servers respectively.

       mechanism specifies the style of discovery to be used.

       The currently supported mechanisms are:

       avahi  This searches for services which are broadcasting using mDNS  via  avahi-daemon(8).
              An  optional  suffix  ",timeout=N" may be added to specify the discovery timeout in
              floating-point multiples of one second.  The default timeout is 0.5 seconds,  which
              may  be  overridden  by  the  AVAHI_DISCOVERY_TIMEOUT  environment  variable,  also
              specified in floating-point multiples of one second. If both  are  specified,  then
              the value specified in the environment variable takes precedence.

              Actively  probes  the given subnet for the requested PCP service(s).  <net-address>
              is an inet or ipv6 network address and <mask-bits> is the number of  bits  used  to
              define  the  subnet. For example, defines an 8 bit subnet consisting
              of  the  addresses  through    An   optional   suffix
              ",maxThreads=N" may be added to limit the number of threads used while probing. The
              default is no fixed limit, which is to say that the process' rlimits for the number
              of  threads  and  open  file  descriptors  will  be  respected.  An optional suffix
              ",timeout=N" may be added to specify the timeout for  each  connection  attempt  in
              floating-point multiples of one second.  The default timeout is 20 milliseconds.

       mechanism may also be NULL, which means to use all available discovery mechanisms.

       For  __pmDiscoverServicesWithOptions, optionsString specifies global options to be applied
       to the discovery process. Options are comma-separated and  may  be  one  or  more  of  the

              This  requests  that  DNS  name  resolution  be  attempted for the addresses of any
              discovered services.

              This specifies  a  timeout  period  after  which  the  discovery  process  will  be
              interrupted. N is a floating point number representing the number of seconds before
              timing out.

       optionsString may also be NULL, which means that no global options are specified.

       For __pmDiscoverServicesWithOptions, flags specifies  a  pointer  to  an  object  of  type
       unsigned  which  is  a  bit  mask  of  options/status flags for the discovery process. The
       supported flags are:

              Specifying this flag is equivalent to specifying resolve in the optionsString

              This flag must be unset when calling __pmDiscoverServicesWithOptions but may be set
              asynchronously  (by  an  interrupt  handler, for example) in order to interrupt the
              service discovery process.

       flags may also be NULL, which indicates that no flags are set.

       pmDiscoverServices and __pmDiscoverServicesWithOptions will return the number of  services
       discovered,  else  a  value less than zero for an error.  The value zero indicates that no
       services were discovered.

       The resulting list of pointers,  urls,  and  the  values  (the  URLs)  that  the  pointers
       reference      will      have      been     allocated     by     pmDiscoverServices     or
       __pmDiscoverServicesWithOptions  with  a  single  call  to  malloc(3C),  and  it  is   the
       responsibility  of  the  pmDiscoverServices  or  __pmDiscoverServicesWithOptions caller to
       free(urls) to release the space when it is no longer required.

       When an error occurs, or no services are discovered, urls is undefined (no space will have
       been allocated, and so calling free(3C) is a singularly bad idea).


       Environment variables with the prefix PCP_ are used to parameterize the file and directory
       names used by PCP.  On each installation, the file /etc/pcp.conf contains the local values
       for  these  variables.   The  $PCP_CONF  variable  may  be  used to specify an alternative
       configuration file, as described in  pcp.conf(5).   Values  for  these  variables  may  be
       obtained programmatically using the pmGetConfig(3) function.


       PMAPI(3),   pmcd(1),   pmproxy(1),   pmwebd(1),  pmfind(1),  pmGetConfig(3),  pcp.conf(5),
       pcp.env(5) and avahi-daemon(8).


              An invalid argument has been specified.

              Unable to allocate memory required to process the request.

              The specified mechanism is not supported.