[{"id":35719,"web_url":"https://patchwork.libcamera.org/comment/35719/","msgid":"<175732707652.2066996.5501680675239932294@neptunite.rasen.tech>","date":"2025-09-08T10:24:36","subject":"Re: [PATCH v16 02/12] config: Make GlobalConfiguration instance","submitter":{"id":17,"url":"https://patchwork.libcamera.org/api/people/17/","name":"Paul Elder","email":"paul.elder@ideasonboard.com"},"content":"Hi Milan,\n\nThanks for the patch.\n\nQuoting Milan Zamazal (2025-07-29 16:31:50)\n> Global configuration is accessed via a GlobalConfiguration instance.\n> The instance is conceptually a singleton, but singletons are not welcome\n> in libcamera so we must store the (preferably single) instance\n> somewhere.\n> \n> This patch creates a GlobalConfiguration instance in CameraManager and\n> defines the corresponding access method. CameraManager is typically\n> instantiated only once or a few times, it is accessible in many places\n> in libcamera and the configuration can be retrieved from it and passed\n> to other places if needed (it's read-only once created). Using\n> CameraManager for the purpose is still suboptimal and we use it only due\n> to lack of better options. An alternative could be Logger, which is\n> still a singleton and it's accessible from everywhere. But with Logger,\n> we have a chicken and egg problem -- GlobalConfiguration should log\n> contingent problems with the configuration when it's loaded but if it is\n> created in the logger then there are mutual infinite recursive calls.\n> One possible way to deal with this is to look at the environment\n> variables only during logging initialisation and apply the logging\n> configuration when a CameraManager is constructed. Considering there\n> are intentions to remove the Logger singleton, let's omit logging\n> configuration for now.\n\nI think putting it in CameraManager is fine. We have other singletons like\nIPAManager and LayerManager living there. It's probably better than making it\nstatic.\n\n> \n> If there are multiple CameraManager instances, there are also multiple\n> GlobalConfiguration instances, each CameraManager instance is meant to\n> be fully independent, including configuration. They may or may not\n> contain the same data, depending on whether the global configuration\n> file in the file system was changed in the meantime.\n> \n> The configuration is stored in CameraManager privately, it's not meant\n\ns/in CameraManager privately/in the private CameraManager/ maybe? \"Privately\"\nmakes it sound like it goes in the private section of the CameraManager class.\n\n> to be accessed by applications.\n> \n> Signed-off-by: Milan Zamazal \n\nThe commit title I think should be\n\"libcamera: camera_manager: Construct GlobalConfiguration instance\"\nas this is touching camera_manager code, not global_configuration code.\n\nLooks good to me.\n\nReviewed-by: Paul Elder \n\n> ---\n> include/libcamera/internal/camera_manager.h | 8 ++++++++\n> src/libcamera/camera_manager.cpp | 8 ++++++++\n> 2 files changed, 16 insertions(+)\n> \n> diff --git a/include/libcamera/internal/camera_manager.h b/include/libcamera/internal/camera_manager.h\n> index 0150ca61f..e8082eb34 100644\n> --- a/include/libcamera/internal/camera_manager.h\n> +++ b/include/libcamera/internal/camera_manager.h\n> @@ -18,6 +18,7 @@\n> #include \n> #include \n> \n> +#include \"libcamera/internal/global_configuration.h\"\n> #include \"libcamera/internal/process.h\"\n> \n> namespace libcamera {\n> @@ -38,6 +39,11 @@ public:\n> void addCamera(std::shared_ptr camera) LIBCAMERA_TSA_EXCLUDES(mutex_);\n> void removeCamera(std::shared_ptr camera) LIBCAMERA_TSA_EXCLUDES(mutex_);\n> \n> + const GlobalConfiguration &configuration() const\n> + {\n> + return configuration_;\n> + }\n> +\n> IPAManager *ipaManager() const { return ipaManager_.get(); }\n> \n> protected:\n> @@ -66,6 +72,8 @@ private:\n> \n> std::unique_ptr ipaManager_;\n> ProcessManager processManager_;\n> +\n> + const GlobalConfiguration configuration_;\n> };\n> \n> } /* namespace libcamera */\n> diff --git a/src/libcamera/camera_manager.cpp b/src/libcamera/camera_manager.cpp\n> index f81794bfd..dca3d9a83 100644\n> --- a/src/libcamera/camera_manager.cpp\n> +++ b/src/libcamera/camera_manager.cpp\n> @@ -15,6 +15,7 @@\n> \n> #include \"libcamera/internal/camera.h\"\n> #include \"libcamera/internal/device_enumerator.h\"\n> +#include \"libcamera/internal/global_configuration.h\"\n> #include \"libcamera/internal/ipa_manager.h\"\n> #include \"libcamera/internal/pipeline_handler.h\"\n> \n> @@ -258,6 +259,13 @@ void CameraManager::Private::removeCamera(std::shared_ptr camera)\n> o->cameraRemoved.emit(camera);\n> }\n> \n> +/**\n> + * \\fn const GlobalConfiguration &CameraManager::Private::configuration() const\n> + * \\brief Get global configuration bound to the camera manager\n> + *\n> + * \\return Reference to the configuration\n> + */\n> +\n> /**\n> * \\fn CameraManager::Private::ipaManager() const\n> * \\brief Retrieve the IPAManager\n> -- \n> 2.50.1\n>","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 5783BC324E\n\tfor ;\n\tMon, 8 Sep 2025 10:24:44 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 12C5E69353;\n\tMon, 8 Sep 2025 12:24:44 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id E200B69338\n\tfor ;\n\tMon, 8 Sep 2025 12:24:42 +0200 (CEST)","from neptunite.rasen.tech (unknown\n\t[IPv6:2404:7a81:160:2100:60ea:3a39:598b:6db8])\n\tby perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 29284C71;\n\tMon, 8 Sep 2025 12:23:29 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"C2g2pXSE\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1757327010;\n\tbh=6KmpMJq/vXIfdSf0L2DAzKhoF5ivd1rgmz/ZmKmmaFY=;\n\th=In-Reply-To:References:Subject:From:Cc:To:Date:From;\n\tb=C2g2pXSEe878TGF4oQ40I6q5k8fAJpYgsOmp3bzwO28ZdEl3Td3vYuT80BT32x4sX\n\tm1wn1iZY4GY3+a9iFvtSd/dheJa+q+M7cPN5x7v2K2kLhjswrF8GWgNO16BxHgLjnj\n\ta9DrAe0kOG0cnndjHgnS+eZ6UxKwVmBjY+u+28UI=","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"<20250729073201.5369-3-mzamazal@redhat.com>","References":"<20250729073201.5369-1-mzamazal@redhat.com>\n\t<20250729073201.5369-3-mzamazal@redhat.com>","Subject":"Re: [PATCH v16 02/12] config: Make GlobalConfiguration instance","From":"Paul Elder ","Cc":"Milan Zamazal , Kieran Bingham\n\t, =?utf-8?q?Barnab=C3=A1s_P=C5=91cze?=\n\t, Laurent Pinchart\n\t","To":"Milan Zamazal , libcamera-devel@lists.libcamera.org","Date":"Mon, 08 Sep 2025 19:24:36 +0900","Message-ID":"<175732707652.2066996.5501680675239932294@neptunite.rasen.tech>","User-Agent":"alot/0.0.0","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}},{"id":35725,"web_url":"https://patchwork.libcamera.org/comment/35725/","msgid":"<85v7ltt5rh.fsf@mzamazal-thinkpadp1gen7.tpbc.csb>","date":"2025-09-08T13:48:02","subject":"Re: [PATCH v16 02/12] config: Make GlobalConfiguration instance","submitter":{"id":177,"url":"https://patchwork.libcamera.org/api/people/177/","name":"Milan Zamazal","email":"mzamazal@redhat.com"},"content":"Hi Paul,\n\nthank you for review.\n\nPaul Elder writes:\n\n> Hi Milan,\n>\n> Thanks for the patch.\n>\n> Quoting Milan Zamazal (2025-07-29 16:31:50)\n>> Global configuration is accessed via a GlobalConfiguration instance.\n>> The instance is conceptually a singleton, but singletons are not welcome\n>> in libcamera so we must store the (preferably single) instance\n>> somewhere.\n>> \n>> This patch creates a GlobalConfiguration instance in CameraManager and\n>> defines the corresponding access method. CameraManager is typically\n>> instantiated only once or a few times, it is accessible in many places\n>> in libcamera and the configuration can be retrieved from it and passed\n>> to other places if needed (it's read-only once created). Using\n>> CameraManager for the purpose is still suboptimal and we use it only due\n>> to lack of better options. An alternative could be Logger, which is\n>> still a singleton and it's accessible from everywhere. But with Logger,\n>> we have a chicken and egg problem -- GlobalConfiguration should log\n>> contingent problems with the configuration when it's loaded but if it is\n>> created in the logger then there are mutual infinite recursive calls.\n>> One possible way to deal with this is to look at the environment\n>> variables only during logging initialisation and apply the logging\n>> configuration when a CameraManager is constructed. Considering there\n>> are intentions to remove the Logger singleton, let's omit logging\n>> configuration for now.\n>\n> I think putting it in CameraManager is fine. We have other singletons like\n> IPAManager and LayerManager living there. It's probably better than making it\n> static.\n>\n>> \n>> If there are multiple CameraManager instances, there are also multiple\n>> GlobalConfiguration instances, each CameraManager instance is meant to\n>> be fully independent, including configuration. They may or may not\n>> contain the same data, depending on whether the global configuration\n>> file in the file system was changed in the meantime.\n>> \n>> The configuration is stored in CameraManager privately, it's not meant\n>\n> s/in CameraManager privately/in the private CameraManager/ maybe? \"Privately\"\n> makes it sound like it goes in the private section of the CameraManager class.\n\nYes, it's meant to be accessible from within libcamera, I'll change the\nwording.\n\n>> to be accessed by applications.\n>> \n>> Signed-off-by: Milan Zamazal \n>\n> The commit title I think should be\n> \"libcamera: camera_manager: Construct GlobalConfiguration instance\"\n> as this is touching camera_manager code, not global_configuration code.\n\nOK.\n\n> Looks good to me.\n>\n> Reviewed-by: Paul Elder \n>\n>> ---\n>> include/libcamera/internal/camera_manager.h | 8 ++++++++\n>> src/libcamera/camera_manager.cpp | 8 ++++++++\n>> 2 files changed, 16 insertions(+)\n>> \n>> diff --git a/include/libcamera/internal/camera_manager.h b/include/libcamera/internal/camera_manager.h\n>> index 0150ca61f..e8082eb34 100644\n>> --- a/include/libcamera/internal/camera_manager.h\n>> +++ b/include/libcamera/internal/camera_manager.h\n>> @@ -18,6 +18,7 @@\n>> #include \n>> #include \n>> \n>> +#include \"libcamera/internal/global_configuration.h\"\n>> #include \"libcamera/internal/process.h\"\n>> \n>> namespace libcamera {\n>> @@ -38,6 +39,11 @@ public:\n>> void addCamera(std::shared_ptr camera) LIBCAMERA_TSA_EXCLUDES(mutex_);\n>> void removeCamera(std::shared_ptr camera) LIBCAMERA_TSA_EXCLUDES(mutex_);\n>> \n>> + const GlobalConfiguration &configuration() const\n>> + {\n>> + return configuration_;\n>> + }\n>> +\n>> IPAManager *ipaManager() const { return ipaManager_.get(); }\n>> \n>> protected:\n>> @@ -66,6 +72,8 @@ private:\n>> \n>> std::unique_ptr ipaManager_;\n>> ProcessManager processManager_;\n>> +\n>> + const GlobalConfiguration configuration_;\n>> };\n>> \n>> } /* namespace libcamera */\n>> diff --git a/src/libcamera/camera_manager.cpp b/src/libcamera/camera_manager.cpp\n>> index f81794bfd..dca3d9a83 100644\n>> --- a/src/libcamera/camera_manager.cpp\n>> +++ b/src/libcamera/camera_manager.cpp\n>> @@ -15,6 +15,7 @@\n>> \n>> #include \"libcamera/internal/camera.h\"\n>> #include \"libcamera/internal/device_enumerator.h\"\n>> +#include \"libcamera/internal/global_configuration.h\"\n>> #include \"libcamera/internal/ipa_manager.h\"\n>> #include \"libcamera/internal/pipeline_handler.h\"\n>> \n>> @@ -258,6 +259,13 @@ void CameraManager::Private::removeCamera(std::shared_ptr camera)\n>> o->cameraRemoved.emit(camera);\n>> }\n>> \n>> +/**\n>> + * \\fn const GlobalConfiguration &CameraManager::Private::configuration() const\n>> + * \\brief Get global configuration bound to the camera manager\n>> + *\n>> + * \\return Reference to the configuration\n>> + */\n>> +\n>> /**\n>> * \\fn CameraManager::Private::ipaManager() const\n>> * \\brief Retrieve the IPAManager\n>> -- \n>> 2.50.1\n>>","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 23D57C324E\n\tfor ;\n\tMon, 8 Sep 2025 13:48:17 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 448986935B;\n\tMon, 8 Sep 2025 15:48:16 +0200 (CEST)","from us-smtp-delivery-124.mimecast.com\n\t(us-smtp-delivery-124.mimecast.com [170.10.133.124])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 8A2736934E\n\tfor ;\n\tMon, 8 Sep 2025 15:48:14 +0200 (CEST)","from mail-ej1-f72.google.com (mail-ej1-f72.google.com\n\t[209.85.218.72]) by relay.mimecast.com with ESMTP with STARTTLS\n\t(version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id\n\tus-mta-548-CorGbmwcMqGnUMQGCzMcEg-1; Mon, 08 Sep 2025 09:48:11 -0400","by mail-ej1-f72.google.com with SMTP id\n\ta640c23a62f3a-b04a302fb7cso190210366b.3\n\tfor ;\n\tMon, 08 Sep 2025 06:48:10 -0700 (PDT)","from mzamazal-thinkpadp1gen7.tpbc.csb\n\t(ip-77-48-47-2.net.vodafone.cz. 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