[{"id":36157,"web_url":"https://patchwork.libcamera.org/comment/36157/","msgid":"<175982342797.756374.1524142483548440556@ping.linuxembedded.co.uk>","date":"2025-10-07T07:50:27","subject":"Re: [RFC PATCH v1 5/7] libcamera: camera: Make `waitingRequests_` an\n\t`std::deque`","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Quoting Barnabás Pőcze (2025-09-24 13:47:10)\n> Use `std::deque` instead of `std::queue` because an `std::queue` cannot\n> be iterated.\n> \n\nI can't imagine any specific performance impact or penalty here. This is\na small list.\n\nReviewed-by: Kieran Bingham \n\n> Signed-off-by: Barnabás Pőcze \n> ---\n> include/libcamera/internal/camera.h | 2 +-\n> src/libcamera/pipeline_handler.cpp | 8 ++++----\n> 2 files changed, 5 insertions(+), 5 deletions(-)\n> \n> diff --git a/include/libcamera/internal/camera.h b/include/libcamera/internal/camera.h\n> index 8a2e9ed58..0f50c14a5 100644\n> --- a/include/libcamera/internal/camera.h\n> +++ b/include/libcamera/internal/camera.h\n> @@ -37,7 +37,7 @@ public:\n> const PipelineHandler *pipe() const { return pipe_.get(); }\n> \n> std::list queuedRequests_;\n> - std::queue waitingRequests_;\n> + std::deque waitingRequests_;\n> ControlInfoMap controlInfo_;\n> ControlList properties_;\n> \n> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp\n> index e5f9e55c9..d0d3fbc79 100644\n> --- a/src/libcamera/pipeline_handler.cpp\n> +++ b/src/libcamera/pipeline_handler.cpp\n> @@ -370,7 +370,7 @@ void PipelineHandler::stop(Camera *camera)\n> * after the device to keep them in order.\n> */\n> Camera::Private *data = camera->_d();\n> - std::queue waitingRequests;\n> + std::deque waitingRequests;\n> waitingRequests.swap(data->waitingRequests_);\n> \n> /* Stop the pipeline handler and let the queued requests complete. */\n> @@ -379,7 +379,7 @@ void PipelineHandler::stop(Camera *camera)\n> /* Cancel and signal as complete all waiting requests. */\n> while (!waitingRequests.empty()) {\n> Request *request = waitingRequests.front();\n> - waitingRequests.pop();\n> + waitingRequests.pop_front();\n> cancelRequest(request);\n> }\n> \n> @@ -461,7 +461,7 @@ void PipelineHandler::queueRequest(Request *request)\n> \n> Camera *camera = request->_d()->camera();\n> Camera::Private *data = camera->_d();\n> - data->waitingRequests_.push(request);\n> + data->waitingRequests_.push_back(request);\n> \n> request->_d()->prepare(300ms);\n> }\n> @@ -510,7 +510,7 @@ void PipelineHandler::doQueueRequests(Camera *camera)\n> * Pop the request first, in case doQueueRequests() is called\n> * recursively from within doQueueRequest()\n> */\n> - data->waitingRequests_.pop();\n> + data->waitingRequests_.pop_front();\n> doQueueRequest(request);\n> }\n> }\n> -- \n> 2.51.0\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 D3CBCBF415\n\tfor ;\n\tTue, 7 Oct 2025 07:50:35 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 062736B5F3;\n\tTue, 7 Oct 2025 09:50:34 +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 437BE6B58E\n\tfor ;\n\tTue, 7 Oct 2025 09:50:31 +0200 (CEST)","from pendragon.ideasonboard.com\n\t(cpc89244-aztw30-2-0-cust6594.18-1.cable.virginm.net [86.31.185.195])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id B6C81EBA;\n\tTue, 7 Oct 2025 09:48:57 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com; 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This is\n> a small list.\n\n`std::queue` uses `std::deque` by default as the underlying container,\nso there should be no difference at all.\n\n\n> \n> Reviewed-by: Kieran Bingham \n> \n>> Signed-off-by: Barnabás Pőcze \n>> ---\n>> include/libcamera/internal/camera.h | 2 +-\n>> src/libcamera/pipeline_handler.cpp | 8 ++++----\n>> 2 files changed, 5 insertions(+), 5 deletions(-)\n>>\n>> diff --git a/include/libcamera/internal/camera.h b/include/libcamera/internal/camera.h\n>> index 8a2e9ed58..0f50c14a5 100644\n>> --- a/include/libcamera/internal/camera.h\n>> +++ b/include/libcamera/internal/camera.h\n>> @@ -37,7 +37,7 @@ public:\n>> const PipelineHandler *pipe() const { return pipe_.get(); }\n>> \n>> std::list queuedRequests_;\n>> - std::queue waitingRequests_;\n>> + std::deque waitingRequests_;\n>> ControlInfoMap controlInfo_;\n>> ControlList properties_;\n>> \n>> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp\n>> index e5f9e55c9..d0d3fbc79 100644\n>> --- a/src/libcamera/pipeline_handler.cpp\n>> +++ b/src/libcamera/pipeline_handler.cpp\n>> @@ -370,7 +370,7 @@ void PipelineHandler::stop(Camera *camera)\n>> * after the device to keep them in order.\n>> */\n>> Camera::Private *data = camera->_d();\n>> - std::queue waitingRequests;\n>> + std::deque waitingRequests;\n>> waitingRequests.swap(data->waitingRequests_);\n>> \n>> /* Stop the pipeline handler and let the queued requests complete. */\n>> @@ -379,7 +379,7 @@ void PipelineHandler::stop(Camera *camera)\n>> /* Cancel and signal as complete all waiting requests. */\n>> while (!waitingRequests.empty()) {\n>> Request *request = waitingRequests.front();\n>> - waitingRequests.pop();\n>> + waitingRequests.pop_front();\n>> cancelRequest(request);\n>> }\n>> \n>> @@ -461,7 +461,7 @@ void PipelineHandler::queueRequest(Request *request)\n>> \n>> Camera *camera = request->_d()->camera();\n>> Camera::Private *data = camera->_d();\n>> - data->waitingRequests_.push(request);\n>> + data->waitingRequests_.push_back(request);\n>> \n>> request->_d()->prepare(300ms);\n>> }\n>> @@ -510,7 +510,7 @@ void PipelineHandler::doQueueRequests(Camera *camera)\n>> * Pop the request first, in case doQueueRequests() is called\n>> * recursively from within doQueueRequest()\n>> */\n>> - data->waitingRequests_.pop();\n>> + data->waitingRequests_.pop_front();\n>> doQueueRequest(request);\n>> }\n>> }\n>> -- \n>> 2.51.0\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 067D2C324C\n\tfor ;\n\tTue, 7 Oct 2025 08:48:06 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 9642E6B5F3;\n\tTue, 7 Oct 2025 10:48:06 +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 93B5C6B58E\n\tfor ;\n\tTue, 7 Oct 2025 10:48:04 +0200 (CEST)","from [192.168.33.24] (185.182.214.142.nat.pool.zt.hu\n\t[185.182.214.142])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 6F9811122;\n\tTue, 7 Oct 2025 10:46:31 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com; 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