NAME¶

pmParseTimeWindow - parse time window command line arguments

C SYNOPSIS¶

#include <pcp/pmapi.h>

int pmParseTimeWindow(const char *swStart, const char *swEnd, const char *swAlign, const char *swOffset, const struct timeval *logStart, const struct timeval *logEnd, struct timeval *rsltStart, struct timeval *rsltEnd, struct timeval *rsltOffset, char **errMsg);

cc ... -lpcp

DESCRIPTION¶

pmParseTimeWindow is designed to encapsulate the interpretation of the -S, -T, -A and -O command line options used by Performance Co-Pilot (PCP) applications to define a time window of interest. The time window is defined by a start time and an end time that constrains the time interval during which the PCP application will retrieve and display performance metrics. In the absence of the -O and -A options to specify an initial sample time origin and time alignment (see below), the PCP application will retrieve the first sample at the start of the time window.

The syntax and meaning of the various argument formats for these options is described in PCPIntro(1).

USAGE¶

pmParseTimeWindow expects to be called with the argument of the -S option as swStart, the argument of the -T option as swEnd, the argument of the -A option as swAlign, and the argument of the -O option as swOffset. Any or all of these parameters may be NULL to indicate that the corresponding command line option was not present.

If the application is using a set of PCP archive logs as the source of performance metrics, you also need to supply the time of the first archive log entry as logStart, and the time of the last archive log entry as logEnd. See pmGetArchiveLabel(3) and pmGetArchiveEnd(3) for how to obtain values for these times.

If the application is manipulating multiple concurrent archive logs, then the caller must resolve how the default time window is to be defined (the union of the time intervals in all archive logs is a likely interpretation).

If the application is using a live feed of performance data, logStart should be the current time (but could be aligned on the next second for example), while logEnd should have its tv_sec component set to INT_MAX.

The rsltStart, rsltEnd and rsltOffset structures must be allocated before calling pmParseTimeWindow.

You also need to set the current PCP reporting time zone to correctly reflect the -z and -Z command line parameters before calling pmParseTimeWindow. See pmUseZone(3) and friends for information on how this is done.

DIAGNOSTICS¶

If the conversion is successful, pmParseTimeWindow returns 1 and fills in rsltStart, rsltEnd and rsltOffset with the start, end, and offset times for the time window defined by the input parameters. The errMsg parameter is not changed when pmParseTimeWindow returns 1.

If the conversion is successful, but the requested alignment could not be performed (e.g. the set of PCP archive logs is too short) the alignment is ignored, rsltStart, rsltEnd and rsltOffset are filled in and pmParseTimeWindow returns 0. In this case, errMsg will point to a warning message in a dynamically allocated buffer. The caller is responsible for releasing the buffer by calling free(3).

If the argument strings could not be parsed, pmParseTimeWindow returns -1. In this case, errMsg will point to an error message in a dynamically allocated buffer. The caller is responsible for releasing the buffer by calling free(3).

SEE ALSO¶

free(3), PMAPI(3), pmGetArchiveEnd(3), pmGetArchiveLabel(3), pmNewContextZone(3), pmNewZone(3), pmParseInterval(3) and pmUseZone(3).