dconfis a low-level configuration system and settings management tool. Its main purpose is to provide aback endtoGSettingson platforms that don't already have configuration storage systems. It depends onGLib.It is part ofGNOMEas of version 3, and is a replacement forGConf.
 | |
 A screenshot of dconf Editor | |
| Developer(s) | The GNOME Project(Allison Lortie) |
|---|---|
| Initial release | September 16, 2009 |
| Stable release | 0.40.0[1] 
/ 13 March 2021 |
| Repository | |
| Written in | C |
| Type | Configuration, settings management |
| License | GNU Lesser General Public License |
| Website | wiki |
Overview
editdconf is a simple key-based configuration system. Keys exist in an unstructured database (but it is intended that keys that logically belong together are grouped together).
Change notification is supported.
Stacking of multiple configuration sources is supported. Mandatory keys are supported.
The stacking can be done at "mount points". For example, the global system configuration can be mounted under/system/inside of each user's configuration space. A single configuration source may appear at multiple points in the hierarchy. For example, in addition to stacking over the normal keys at/user/,the system default keys may also appear at/default/for inspection and modification by a system policy configuration utility.
PolicyKitintegration is planned so that a normal user may temporarily gain the ability to, for example, write to the keys under/system/(or/default/). This means that programs like theGNOME Display Managerconfiguration utility no longer have to be run as root.
dconf is loosely the GNOME equivalent of theWindows Registry.
Software architecture
editSince a typical GNOME login consists of thousands of reads and ideally 0 writes, dconf is optimized for reads. Typically, reading a key from dconf involves zero system calls and zero context switches. This is achieved with a simple file format that doubles both as the storage format for data in dconf and as anIPCmechanism between the clients and the server.
Avoiding round trips and context switches is desirable in itself, but the real advantage[citation needed]comes from allowing the I/O scheduler in thekernelto do a better job by saturating it with requests coming from all of the applications trying to read their keys (as opposed to a common configuration server serially requesting a single key at a time).
Having all of the keys in a single compact binary format also avoids the intense fragmentation problems currently experienced by the tree-of-directories-of-xml-files approach.
Writes are less optimized – they traverse the bus and are handled by a "writer" – aD-Busservice – in the ordinary way. Change notification is also handled by the writer. The reason for having a bus service at all is that getting the clients to synchronize on writing would be very difficult.[citation needed]
The writer service doesn't have to be activated until the first write operation is performed.
The service is completely stateless and can start and stop dynamically. The list of change notifications that an individual client is interested in is maintained by the bus daemon (as a D-Bus signal watch/match list).
dconf database
editOne dconf database consists of a single file in binary format, i.e. it is not a text-file. The format is defined asgvdb(GVariant Database file). It is a simple database file format that stores a mapping from strings to GVariant values in a way that is extremely efficient for lookups.
The GNOME database file for each user is by default~/.config/dconf/user,a file expected to be in GVDB format.
GVariant
editGVariant is a strongly typedvariant datatypeused for all the values stored in dconf; it can contain one or more values along with information about the type of the values.
A GVariant may contain simple types, like integers, or Boolean values; or complex types, like an array of two strings, or a dictionary of key value pairs. A GVariant is also immutable: once it's been created, neither its type nor its content can be modified further. GVariant is useful whenever data needs to be serialized, for example when sending method parameters in DBus, or when saving settings using GSettings.
GVariant is part of GLib.
- https://developer.gnome.org/glib/stable/glib-GVariant.html
- https://git.gnome.org/browse/glib/tree/glib/gvariant.c[permanent dead link]
GSettings
editThe GSettings class provides a high-level API for application for storing and retrieving their own settings.
In Debian, the utility program/usr/bin/gsettingsis contained in the packagelibglib2.0-bin.
GSettings is part ofGIO.[2]which is part of GLib.libglib2.0-0
Documentation
editA system administratorsguidefor dconf is available. Since version 0.2, dconf is licensed under theLGPLversion 2.1 "or later".
History
editRelease history
edit| Version | Release date | Significant changes |
|---|---|---|
| 0.1 | 2009-09-18 | |
| 0.2 | 2009-10-27 | |
| 0.3 | 2010-05-25 | |
| 0.4 | 2010-07-12 | |
| 0.5 | 2010-09-15 | |
| 0.6 | 2010-12-21 | |
| 0.7 | 2011-05-09 | |
| 0.8 | 2011-07-26 | |
| 0.9 | 2011-09-19 | |
| 0.10 | 2011-09-26 | |
| 0.11 | 2012-03-19 | |
| 0.12 | 2012-05-01 | |
| 0.13 | 2012-08-20 | |
| 0.14 | 2012-11-01 | |
| 0.15 | 2013-02-11 | |
| 0.16 | 2013-07-16 | |
| 0.17 | 2013-09-16 | |
| 0.18 | 2013-09-23 | |
| 0.19 | 2014-03-17 | |
| 0.20 | 2014-03-24 | dconf compile: always writelittle endian |
| 0.21 | 2014-07-22 | |
| 0.22 | 2014-09-19 | |
| 0.23 | 2015-03-16 | split dconf-editor into a separate package |
| 0.24 | 2015-03-23 | |
| 0.25 | 2015-12-16 | |
| 0.26 | 2016-03-23 | libdbus-1 back-end removed; dconf now always usesGDBus |
| 0.27 | 2017-10-17 | Port toMeson build system(#784910) |
References
edit- ^"Release 0.40.0".13 March 2021.Retrieved10 April2021.
- ^"gio/gsettings.c · master · GNOME / GLib".GitLab.Retrieved22 April2018.[permanent dead link]
