'\"macro stdmacro
.\"
.\" Copyright (c) 2010 Ken McDonell.  All Rights Reserved.
.\" Copyright (c) 2018,2022 Red Hat.
.\"
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.\" under the terms of the GNU General Public License as published by the
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.TH PMISTART 3 "" "Performance Co-Pilot"
.SH NAME
\f3pmiStart\f1 \- establish a new LOGIMPORT context
.SH "C SYNOPSIS"
.ft 3
#include <pcp/pmapi.h>
.br
#include <pcp/import.h>
.sp
int pmiStart(const char *\fIarchive\fP, int \fIinherit\fP);
.sp
cc ... \-lpcp_import \-lpcp
.ft 1
.SH "Perl SYNOPSIS"
.ft 3
use PCP::LogImport;
.sp
pmiStart($\fIarchive\fP, $\fIinherit\fP);
.ft 1
.SH DESCRIPTION
As part of the Performance Co-Pilot Log Import API (see
.BR LOGIMPORT (3)),
.B pmiStart
creates a new context.
Each context maintains the following state and metadata:
.IP \(bu 3n
The base name (\c
.IR archive )
for the physical  files
that constitute the output PCP archive.
.IP \(bu 3n
The source hostname for the data that will be written to the
PCP archive.
Defaults to the hostname of the localhost, but can be set using
.BR pmiSetHostname (3).
.IP \(bu 3n
The source timezone for the
PCP archive.
Defaults to the timezone of the localhost, but can be set using
.BR pmiSetTimezone (3).
.IP \(bu 3n
The output archive version number for the
PCP archive.
Defaults to the traditional version 2 format, but can be set using
.BR pmiSetVersion (3).
.IP \(bu 3n
Metrics and instance domains, as defined by
.BR pmiAddMetric (3).
.IP \(bu 3n
Instances for each instance domain, as defined by
.BR pmiAddInstance (3).
.IP \(bu 3n
Handles as defined by
.BR pmiGetHandle (3).
Each handle is a metric-instance pair, and each metric-instance pair
may have an associated value in each record written to the output
PCP archive.
.IP \(bu 3n
An optional set of data values for one or more metric-instance pairs
(ready for the next record to be written
to the output PCP archive) as defined
by calls to
.BR pmPutValue (3)
or
.BR pmPutValuehandle (3).
.PP
If
.I inherit
is true, then the new context will inherit any and all
metadata (metrics, instance domains, instances and handles) from the current
context, otherwise the new context is created with no metadata.
The basename for the output PCP archive, the source hostname, the
source timezone and any data values from the current context are
.B not
inherited.
If this is the first call to
.B pmiStart
the metadata will be empty
independent of the value of
.IR inherit .
.PP
Since no physical files for the output PCP archive
will be created until the first call to
.BR pmiWrite (3)
or
.BR pmiPutRecord(3),
.I archive
could be NULL to create a
convenience context that is populated with metadata to be
inherited by subsequent contexts.
.PP
The return value is a context identifier that
could be used in a subsequent call to
.BR pmUseContext (3)
and the
new context becomes the current context which
persists for all subsequent calls up to either another
.B pmiStart
call or a call to
.BR pmiUseContext (3)
or a call to
.BR pmiEnd (3).
.SH DIAGNOSTICS
It is an error if the physical files
\fIarchive\fR.\fB0\fR and/or
\fIarchive\fR.\fBindex\fR and/or
\fIarchive\fR.\fBmeta\fR already exist, but this is not discovered
until the first attempt is made to output some data by calling
.BR pmiWrite (3)
or
.BR pmiPutRecord(3),
so
.B pmiStart
always returns a positive context identifier.
.SH SEE ALSO
.BR LOGIMPORT (3),
.BR pmiAddInstance (3),
.BR pmiAddMetric (3),
.BR pmiEnd (3),
.BR pmiErrStr (3),
.BR pmiGetHandle (3),
.BR pmiPutResult (3),
.BR pmiPutValue (3),
.BR pmiPutValueHandle (3),
.BR pmiPutText (3),
.BR pmiPutLabel (3),
.BR pmiSetHostname (3),
.BR pmiSetTimezone (3),
.BR pmiSetVersion (3),
.BR pmiUseContext (3)
and
.BR pmiWrite (3).