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NAME | C SYNOPSIS | DESCRIPTION | DIAGNOSTICS | PCP ENVIRONMENT | SEE ALSO | COLOPHON |
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PMGETARCHIVELABEL(3) Library Functions Manual PMGETARCHIVELABEL(3)
pmGetArchiveLabel, pmGetHighResArchiveLabel - fetch the label
record from a set of performance metrics archives
#include <pcp/pmapi.h>
int pmGetArchiveLabel(pmLogLabel *lp);
int pmGetHighResArchiveLabel(pmHighResLogLabel *lp);
cc ... -lpcp
Within the framework of the Performance Co-Pilot (PCP), archives
of performance metrics values may be accumulated and saved using
the program pmlogger(1) and the LOGIMPORT(3) programming
interface.
The routines pmGetArchiveLabel and pmGetHighResArchiveLabel may
be used to fetch the label record from a set of archives that has
already been opened using pmNewContext(3), or pmDupContext(3),
and thereby associated with the current Performance Metrics
Application Programming Interface (PMAPI) context.
It is recommended that new applications use the high resolution
API and existing applications transition to this interface over
time.
The result returned via the pointer lp is a structure that must
be pre-allocated by the caller and has one of the following two
formats (defined in pmapi.h).
typedef struct {
int magic; /* PM_LOG_MAGIC | archive format version no. */
pid_t pid; /* PID of logger */
struct timespec start; /* start of this archive */
char hostname[PM_MAX_HOSTNAMELEN]; /* collection host full name */
char timezone[PM_MAX_TIMEZONELEN]; /* generic, squashed $TZ */
char zoneinfo[PM_MAX_ZONEINFOLEN]; /* local platform $TZ */
} pmHighResLogLabel;
typedef struct {
int ll_magic; /* PM_LOG_MAGIC | archive format version no. */
pid_t ll_pid; /* PID of logger */
struct timeval ll_start;/* start of this archive */
char ll_hostname[PM_LOG_MAXHOSTLEN]; /* name of collection host */
char ll_tz[40]; /* $TZ at collection host */
} pmLogLabel;
Both forms can be used with either version 2 or version 3
archives. However, the pmHighResLogLabel structure provides the
higher resolution start time stored in the newer format, as well
as the full timezone and extended length host name fields. For
detailed information about the archive on-disk format, refer to
LOGARCHIVE(5).
For an application using pmGetHighResArchiveLabel, the most
useful information from the archive label is likely to be in the
fields start, hostname, timezone, and zoneinfo.
The zoneinfo field contains the most detailed timezone
information available, and should be used if present (non-zero
length string). It will only not be present in the case of
version 2 archives - this is a new field added as part of the
version 3 format. The timezone field will always be present,
however it is the 'squashed' timezone value and in certain
situations is not the most accurate timezone.
For older applications using pmGetArchiveLabel, the most useful
information from the archive label is likely to be in the fields
ll_start, ll_hostname or ll_tz. Note that the size of the
ll_hostname field is PM_LOG_MAXHOSTLEN (64 bytes) which is less
than MAXHOSTNAMELEN (see gethostbyname(3)) on some platforms.
These semantics are necessary to retain backwards compatibility
with the PCP archive file format.
Both pmGetArchiveLabel and pmGetHighResArchiveLabel return zero
for success.
PM_ERR_NOCONTEXT
the current PMAPI context is either invalid, or not
associated with a set of archives
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.
pmlogger(1), LOGIMPORT(3), PMAPI(3), pmDupContext(3),
pmGetConfig(3), pmNewContext(3), LOGARCHIVE(5), 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 PMGETARCHIVELABEL(3)
Pages that refer to this page: pmgetarchiveend(3), pmgetcontexthostname(3), __pmparsetime(3), pmparsetimewindow(3)
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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. |
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