.\" Automatically generated by Pandoc 2.2.1
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.TH "PMEM_CTL" "5" "2019-02-19" "PMDK - pmem_ctl API version 1.4" "PMDK Programmer's Manual"
.hy
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.SH NAME
.PP
ctl \- interface for examination and modification of the library's
internal state.
.SH DESCRIPTION
.PP
The CTL namespace is organized in a tree structure.
Starting from the root, each node can be either internal, containing
other elements, or a leaf.
Internal nodes themselves can only contain other nodes and cannot be
entry points.
There are two types of those nodes: \f[I]named\f[] and \f[I]indexed\f[].
Named nodes have string identifiers.
Indexed nodes represent an abstract array index and have an associated
string identifier.
The index itself is provided by the user.
A collection of indexes present on the path of an entry point is
provided to the handler functions as name and index pairs.
.PP
Entry points are the leaves of the CTL namespace structure.
Each entry point can read from the internal state, write to the internal
state, exec a function or a combination of these operations.
.PP
The entry points are listed in the following format:
.PP
name | r(ead)w(rite)x(ecute) | global/\- | read argument type | write
argument type | exec argument type | config argument type
.PP
A description of \f[B]pmem_ctl\f[] functions can be found on the
following manual pages: \f[B]libpmemblk_ctl_get\f[](3),
\f[B]libpmemlog_ctl_get\f[](3), \f[B]libpmemobj_ctl_get\f[](3)
.SH CTL EXTERNAL CONFIGURATION
.PP
In addition to direct function call, each write entry point can also be
set using two alternative methods.
.PP
The first method is to load a configuration directly from the
\f[B]PMEMBLK_CONF\f[]/ \f[B]PMEMLOG_CONF\f[]/ \f[B]PMEMOBJ_CONF\f[]
environment variable.
A properly formatted ctl config string is a single\-line sequence of
queries separated by `;':
.IP
.nf
\f[C]
query0;query1;...;queryN
\f[]
.fi
.PP
A single query is constructed from the name of the ctl write entry point
and the argument, separated by `=':
.IP
.nf
\f[C]
entry_point=entry_point_argument
\f[]
.fi
.PP
The entry point argument type is defined by the entry point itself, but
there are three predefined primitives:
.IP
.nf
\f[C]
*)\ integer:\ represented\ by\ a\ sequence\ of\ [0\-9]\ characters\ that\ form
\ \ \ \ a\ single\ number.
*)\ boolean:\ represented\ by\ a\ single\ character:\ y/n/Y/N/0/1,\ each
\ \ \ \ corresponds\ to\ true\ or\ false.\ If\ the\ argument\ contains\ any
\ \ \ \ trailing\ characters,\ they\ are\ ignored.
*)\ string:\ a\ simple\ sequence\ of\ characters.
\f[]
.fi
.PP
There are also complex argument types that are formed from the
primitives separated by a `,':
.IP
.nf
\f[C]
first_arg,second_arg
\f[]
.fi
.PP
In summary, a full configuration sequence looks like this:
.IP
.nf
\f[C]
(first_entry_point)=(arguments,\ ...);...;(last_entry_point)=(arguments,\ ...);
\f[]
.fi
.PP
As an example, to set both prefault at_open and at_create variables:
.IP
.nf
\f[C]

PMEMBLK_CONF="prefault.at_open=1;prefault.at_create=1"
\f[]
.fi
.PP
The second method of loading an external configuration is to set the
\f[B]PMEMBLK_CONF_FILE\f[]/ \f[B]PMEMLOG_CONF_FILE\f[]/
\f[B]PMEMOBJ_CONF_FILE\f[] environment variable to point to a file that
contains a sequence of ctl queries.
The parsing rules are all the same, but the file can also contain
white\-spaces and comments.
.PP
To create a comment, simply use `#' anywhere in a line and everything
afterwards, until a new line, will be ignored.
.PP
An example configuration file:
.IP
.nf
\f[C]
#########################
#\ My\ pmemblk\ configuration
#########################
#
#\ Global\ settings:
prefault.\ #\ modify\ the\ behavior\ of\ pre\-faulting
\ \ \ \ at_open\ =\ 1;\ #\ prefault\ when\ the\ pool\ is\ opened

prefault.
\ \ \ \ at_create\ =\ 0;\ #\ but\ don\[aq]t\ prefault\ when\ it\[aq]s\ created

#\ Per\-pool\ settings:
#\ ...
\f[]
.fi
.SH SEE ALSO
.PP
\f[B]libpmemblk_ctl_get\f[](3), \f[B]libpmemlog_ctl_get\f[](3),
\f[B]libpmemobj_ctl_get\f[](3) and \f[B]<http://pmem.io>\f[]