быстрый, масштабируемый запрос временных рядов (fast, scalable time series querying)
Имя (Name)
pmSeriesQuery, pmSeriesValues, pmSeriesLoad - fast, scalable time
series querying
Синопсис C (C Synopsis)
#include <pcp/pmwebapi.h>
int pmSeriesQuery(pmSeriesSettings *sp, sds *query, pmSeriesFlags
flags, void *arg);
int pmSeriesValues(pmSeriesSettings *sp, pmSeriesTimeWindow
*window, int count, sds *series, void *arg);
int pmSeriesLoad(pmSeriesSettings *sp, sds *query, pmSeriesFlags
flags, void *arg);
cc ... -lpcp_web
Описание (Description)
Searching for time series identifiers and values using the
Performance Co-Pilot (PCP) fast, scalable time series services is
achieved using the pmseries(1) utility, and associated pmproxy(1)
REST API service.
The implementation of these facilities is shared and available
for other programs to use as well. The functionality is provided
through asynchronous APIs, which function in an event-driven
fashion where callbacks are invoked for each set of series
identifiers or values structure being returned. These callbacks
must be registered using pmSeriesSetup(3) before any query API
calls are made.
As a general pattern, these interfaces take an opaque (void *
pointer) parameter, arg. This pointer will be passed through
unchanged and is typically used to access a data structure
maintaining state within the calling program.
Depending on the pmseries query string provided, pmSeriesQuery
operates in one of two modes.
Firstly, if no time window specification is provided (square
brackets), then the interface will return only matching series
identifiers and no values. These identifiers are returned via
the on_match callback registered using pmSeriesSetup. If the
query expression includes function calls or arithmetic operators
(rather than simple metric names), then the returned identifier
is dynamically created and persistently associated with the
expression. The query expression may be retrieved with the
pmSeriesExprs(3) API call. See also PMWEBAPI(3) and the -e
option to pmseries(1).
The second mode is where a time window specification is used in
the query string, or when the pmSeriesValues interface is used.
This mode provides values and time stamps for all matching time
series identifiers having data points within the provided time
window. In this case, the results are returned via the on_value
callback registered using pmSeriesSetup.
Further metadata (metric names, labels, units, semantics, type,
etc) about matched time series and their values can be obtained
using the interfaces described on the pmSeriesDescs(3) manual
page.
Typically, loading of time series is handled automatically by the
pmproxy daemon, which uses the pmDiscoverSetup(3) series of
interfaces to automatically detect and load logged time series
from pmlogger(1). However, it is also possible to manually load
time series from a PCP archive using the pmSeriesLoad interface.
The provided query string must provide an archive or directory to
load data from using the source.path keyword.
Диагностика (Diagnostic)
Where these functions return a status code, this is always zero
on success. On failure a negative PMAPI error code is returned.
Смотри также (See also)
pmproxy(1), pmlogger(1), pmSeriesSetup(3), pmSeriesDescs(3),
pmDiscoverSetup(3), PMAPI(3) and PMWEBAPI(3).
