[PATCH v8 00/15] Add global configuration file

[Barnabás Pőcze]

Hi


2025. 04. 30. 14:14 keltezéssel, Milan Zamazal írta:
> This patch series introduces global configuration file for libcamera, to
> provide runtime configuration means other than environment variables.
> Instead of, or in addition to, the growing list of configuration
> environment variables, the whole configuration can be specified in a
> single configuration file.  This is both simpler and more flexible.
> 
> This is not a replacement for specific configuration files already
> present in libcamera.
> 
> The patches implement what is needed to introduce a configuration file
> that can handle the current environment variables and software ISP
> TODOs.  They demonstrate how to deal with the key points that must be
> considered.  See commit messages for more details.
> 
> The configuration file is a YAML file.  It is looked up in user’s home
> directory or, if not present, in system-wide libcamera directories.
> Both the directories and file name of the configuration file can be
> overridden using newly introduced environment variables.
> 
> The current configuration environment variables are still supported and
> take precedence, if defined, over the corresponding entries in the YAML
> file.
> 
> This patch series is not exhaustive, there can be future enhancements,
> most notably configuration file validation to avoid confusions caused by
> typos etc.
> 
> Not everything has been tested because some of the patches are related
> to specific hardware.
> 
> Also, not everything is necessarily C++ elegant, suggestions for
> improvements are welcome.  Note that there is an obstacle in that
> configuration initialization may call logging and logging queries
> configuration, as explained in the commit messages.  This complicates
> transparent encapsulation.

I think generally the direction is to eliminate singletons from libcamera.[0][1]
So I am not sure that a new one should be introduced. I believe we should proceed
towards a design where the configuration is per-CameraManager (e.g. the constructor
loads the configuration), and then it is propagated to other components. (As far as
I can see, this shouldn't be too much trouble: pipeline handlers can reach the CameraManager
easily, and `DebayerCpu` can receive the settings in its constructor via `SoftwareISP`
from the simple pipeline handler, `IPAManager` can receive it in its constructor).

Secondly, I would consider dropping the logging related settings from the configuration
file, at least for now. It is likely not the most interesting part, and even with the
singleton design, I am not fan of the quite fragile `GlobalConfiguration::initialize()`
call in the `IPAManager` constructor. (With per-CameraManager configuration, I could
imagine that the constructor initializes the logger based on the configuration. Of
course if two CameraManagers load different configuration, then it is entirely possible
that they will overwrite each other's log settings, but unless we want to inject
separate logger objects into each object of interest, I don't really see a nice
solution; but it's probably not a big issue anyways.)

Thoughts?

[0]: https://bugs.libcamera.org/show_bug.cgi?id=246
[1]: https://lists.libcamera.org/pipermail/libcamera-devel/2025-April/049888.html


Regards,
Barnabás Pőcze


> 
> Changes in v8:
> - Rebased on current master.
> - Anniversary edition: 400 days since v1 posted. ;-)
> 
> Changes in v7:
> - Rebased on current master.
> - Tuning file path configuration updated for recent changes.
>    A significant change is that the tuning file configuration is no
>    longer sensor dependent as there is apparently no access to the sensor
>    info in the IPA proxy.
> - Minor improvements of some commit messages.
> 
> Changes in v6:
> - Rebased on master.
> - File names from file header descriptions removed.
> - Indentation fix in moved code as requested by checkstyle.py.
> - Unneeded const_cast's removed.
> - Using GlobalConfiguration namespace rather than a class.
> - Path configuration options are defined as sequences in YAML.
> - A patch introducing LIBCAMERA_CONFIG_NAME added.
> - A patch introducing LIBCAMERA_CONFIG_DIR added.
> - Miscellaneous minor code changes suggested by Barnabás.
> 
> Changes in v5:
> - A pointer is used to store the global configuration singleton rather
>    than a static variable.  This makes the things more robust and fixes
>    the problem with re-entrancy on logging and a failing
>    camera_reconfigure test.
> - In relation to the change above, a new initialization method
>    GlobalConfiguration::initialize() was introduced that replaces the
>    initialization calls in CameraManager and IPAManager.
> - Logging YAML errors when reading the configuration was also fixed.
> - Global configuration is placed to base directly, without an
>    intermediate patch.
> - An `optional' value comparison simplified.
> - A temporary typo in a comment fixed.
> - Unused stdint.h include removed.
> 
> Changes in v4:
> - Rebased on current master.
> - Configuration option for LIBCAMERA_IPA_PROXY_PATH added.
> - Added a patch to include stdlib.h instead of cstdlib in yaml_parser.cpp.
> 
> Changes in v3:
> - Added a configuration item for the newly introduced
>    LIBCAMERA_PIPELINES_MATCH_LIST variable.
> - A minor indentation fix.
> - Fixed `pipelines.' x `pipeline.' configuration item naming mismatch.
> - Tuning files are looked up now by particular cameras attached rather than
>    being specified for the whole pipeline.
> - Helpers use std::string& instead of char* for confPath arguments.
> - Protection against returning YamlObject::empty as a regular value (the
>    problem has been probably exposed by addition of
>    LIBCAMERA_PIPELINES_MATCH_LIST).
> 
> Changes in v2:
> - Rebased on master.
> - Various cleanups, documentation improvements and minor fixes.
> - Configuration option for LIBCAMERA_RPI_TUNING_FILE added (Naush).
> - Two more patches for software ISP configuration added.
> 
> Milan Zamazal (15):
>    yaml: Move yaml_parser.cpp to base
>    config: Introduce global runtime configuration
>    config: Look up logging levels in the configuration file
>    config: Add configuration retrieval helpers
>    config: Look up log file in configuration file
>    config: Look up log color configuration in configuration file
>    config: Look up rpi config path in configuration file
>    config: Look up IPA configurables in configuration file
>    config: Look up pipelines match list in configuration file
>    config: Allow enabling software ISP in runtime
>    config: Add global configuration file documentation
>    libcamera: software_isp: Make input buffer copying configurable
>    libcamera: software_isp: Make measurement configurable
>    config: Make configuration file configurable
>    config: Make configuration directories configurable
> 
>   Documentation/documentation-contents.rst      |   2 +-
>   Documentation/index.rst                       |   2 +-
>   Documentation/meson.build                     |   2 +-
>   ...ariables.rst => runtime_configuration.rst} | 133 +++++++-
>   .../libcamera/internal/global_configuration.h |  60 ++++
>   include/libcamera/internal/meson.build        |   1 +
>   src/libcamera/base/global_configuration.cpp   | 289 ++++++++++++++++++
>   src/libcamera/base/log.cpp                    |  40 +--
>   src/libcamera/base/meson.build                |  15 +
>   src/libcamera/{ => base}/yaml_parser.cpp      |  13 +-
>   src/libcamera/camera_manager.cpp              |  10 +-
>   src/libcamera/ipa_manager.cpp                 |  35 ++-
>   src/libcamera/ipa_proxy.cpp                   |  65 ++--
>   src/libcamera/meson.build                     |  14 -
>   .../pipeline/rpi/common/pipeline_base.cpp     |   8 +-
>   src/libcamera/pipeline/simple/simple.cpp      |  12 +
>   src/libcamera/process.cpp                     |  11 +-
>   src/libcamera/software_isp/TODO               |  36 ---
>   src/libcamera/software_isp/debayer_cpu.cpp    |  30 +-
>   src/libcamera/software_isp/debayer_cpu.h      |   7 +-
>   20 files changed, 630 insertions(+), 155 deletions(-)
>   rename Documentation/{environment_variables.rst => runtime_configuration.rst} (58%)
>   create mode 100644 include/libcamera/internal/global_configuration.h
>   create mode 100644 src/libcamera/base/global_configuration.cpp
>   rename src/libcamera/{ => base}/yaml_parser.cpp (98%)
>