|
HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|
|
NAME | C SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | PCP ENVIRONMENT | SEE ALSO | COLOPHON |
|
|
|
PMGETCONTEXTHOSTNAME(3) Library Functions Manual PMGETCONTEXTHOSTNAME(3)
pmGetHostName, pmGetContextHostName, pmGetContextHostName_r -
return the hostname associated with a Performance Co-Pilot
context
#include <pcp/pmapi.h>
int pmGetHostName(int id, char *buf, int buflen);
const char *pmGetContextHostName(int id);
char *pmGetContextHostName_r(int id, char *buf, int buflen);
cc ... -lpcp
Given a valid PCP context identifier previously created with
pmNewContext(3) or pmDupContext(3), the pmGetContextHostName
function returns the hostname associated with id. The
pmGetContextHostName_r function does the same, but stores the
result in a user-supplied buffer buf of length buflen, which
should have room for at least MAXHOSTNAMELEN bytes. The
pmGetHostName function behaves similarly again, but returns a
status code to indicate success or failure.
If the context id is associated with an archive source of data,
the hostname returned is extracted from the archive label using
pmGetArchiveLabel(3).
For live contexts, an attempt will first be made to retrieve the
hostname from the PCP collector system using pmFetch(3) with the
pmcd.hostname metric. This allows client tools using this
interface to retrieve an accurate host identifier even in the
presence of port forwarding and tunnelled connections.
Should this not succeed, then a fallback method is used. For
local contexts - with local meaning any of DSO, ``localhost'' or
Unix domain socket connection - a hostname will be sought via
gethostname(3). For other contexts, the hostname extracted from
the initial context host specification will be used.
If id is not a valid PCP context identifier, the returned
hostname is a zero length string.
On failure, the return code of pmGetHostName is a negative PMAPI
error code which can be processed by pmErrStr_r(3) for
diagnostics relating to the failure to obtain the context
hostname.
pmGetContextHostName returns a pointer to a static buffer, so the
returned value is only valid until the next call to
pmGetContextHostName and hence is not thread-safe. Multi-
threaded applications should use pmGetHostName or
pmGetContextHostName_r instead.
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.
PCPIntro(1), PMAPI(3), gethostname(3), pmDupContext(3),
pmErrStr_r(3), pmFetch(3), pmGetArchiveLabel(3), pmNewContext(3),
pcp.conf(5) and pcp.env(5).
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 [email protected]. This page was obtained from the
project's upstream Git repository
⟨https://github.com/performancecopilot/pcp.git⟩ on 2024-06-14.
(At that time, the date of the most recent commit that was found
in the repository was 2024-06-14.) 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
[email protected]
Performance Co-Pilot PCP PMGETCONTEXTHOSTNAME(3)
|
HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|