[{"id":38189,"web_url":"https://patchwork.libcamera.org/comment/38189/","msgid":"<177090052666.3376561.9665687379376145993@ping.linuxembedded.co.uk>","date":"2026-02-12T12:48:46","subject":"Re: [PATCH] libcamera: Replace iterators with structured bindings","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Quoting Laurent Pinchart (2026-02-12 12:35:55)\n> Use structured bindings when iterating over a map in range-based for\n> loops. This improves readability.\n\nI think you know my dislike for .first/.second readability\nso this is a very easy:\n\nReviewed-by: Kieran Bingham \n\n> \n> Signed-off-by: Laurent Pinchart \n> ---\n> src/libcamera/pipeline/ipu3/ipu3.cpp | 11 +++--------\n> src/libcamera/pipeline/vimc/vimc.cpp | 3 +--\n> src/libcamera/v4l2_videodevice.cpp | 6 ++----\n> 3 files changed, 6 insertions(+), 14 deletions(-)\n> \n> diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp\n> index 0190f677e679..d1d4d85ebe76 100644\n> --- a/src/libcamera/pipeline/ipu3/ipu3.cpp\n> +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp\n> @@ -791,8 +791,7 @@ void IPU3CameraData::cancelPendingRequests()\n> while (!pendingRequests_.empty()) {\n> Request *request = pendingRequests_.front();\n> \n> - for (auto it : request->buffers()) {\n> - FrameBuffer *buffer = it.second;\n> + for (auto [stream, buffer] : request->buffers()) {\n> buffer->_d()->cancel();\n> pipe()->completeBuffer(request, buffer);\n> }\n> @@ -1225,10 +1224,7 @@ void IPU3CameraData::paramsComputed(unsigned int id)\n> return;\n> \n> /* Queue all buffers from the request aimed for the ImgU. */\n> - for (auto it : info->request->buffers()) {\n> - const Stream *stream = it.first;\n> - FrameBuffer *outbuffer = it.second;\n> -\n> + for (auto [stream, outbuffer] : info->request->buffers()) {\n> if (stream == &outStream_)\n> imgu_->output_->queueBuffer(outbuffer);\n> else if (stream == &vfStream_)\n> @@ -1304,8 +1300,7 @@ void IPU3CameraData::cio2BufferReady(FrameBuffer *buffer)\n> \n> /* If the buffer is cancelled force a complete of the whole request. */\n> if (buffer->metadata().status == FrameMetadata::FrameCancelled) {\n> - for (auto it : request->buffers()) {\n> - FrameBuffer *b = it.second;\n> + for (auto [stream, b] : request->buffers()) {\n> b->_d()->cancel();\n> pipe()->completeBuffer(request, b);\n> }\n> diff --git a/src/libcamera/pipeline/vimc/vimc.cpp b/src/libcamera/pipeline/vimc/vimc.cpp\n> index 4a03c149a617..025e7dbdd26f 100644\n> --- a/src/libcamera/pipeline/vimc/vimc.cpp\n> +++ b/src/libcamera/pipeline/vimc/vimc.cpp\n> @@ -607,8 +607,7 @@ void VimcCameraData::imageBufferReady(FrameBuffer *buffer)\n> \n> /* If the buffer is cancelled force a complete of the whole request. */\n> if (buffer->metadata().status == FrameMetadata::FrameCancelled) {\n> - for (auto it : request->buffers()) {\n> - FrameBuffer *b = it.second;\n> + for (auto [stream, b] : request->buffers()) {\n> b->_d()->cancel();\n> pipe->completeBuffer(request, b);\n> }\n> diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp\n> index 25b61d049a0e..02c50886a084 100644\n> --- a/src/libcamera/v4l2_videodevice.cpp\n> +++ b/src/libcamera/v4l2_videodevice.cpp\n> @@ -2042,10 +2042,8 @@ int V4L2VideoDevice::streamOff()\n> state_ = State::Stopping;\n> \n> /* Send back all queued buffers. */\n> - for (auto it : queuedBuffers_) {\n> - FrameBuffer *buffer = it.second;\n> -\n> - cache_->put(it.first);\n> + for (auto [id, buffer] : queuedBuffers_) {\n> + cache_->put(id);\n> buffer->_d()->cancel();\n> bufferReady.emit(buffer);\n> }\n> \n> base-commit: 1dcf9957a47fb54fce4fbae9daec0b587e52562e\n> -- \n> Regards,\n> \n> Laurent Pinchart\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 522DABD78E\n\tfor ;\n\tThu, 12 Feb 2026 12:48:52 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 343F5621D0;\n\tThu, 12 Feb 2026 13:48:51 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 1242661FBF\n\tfor ;\n\tThu, 12 Feb 2026 13:48:50 +0100 (CET)","from monstersaurus.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 E133511EB;\n\tThu, 12 Feb 2026 13:48:01 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; 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This improves readability.\n> \n> Signed-off-by: Laurent Pinchart \n> ---\n> src/libcamera/pipeline/ipu3/ipu3.cpp | 11 +++--------\n> src/libcamera/pipeline/vimc/vimc.cpp | 3 +--\n> src/libcamera/v4l2_videodevice.cpp | 6 ++----\n> 3 files changed, 6 insertions(+), 14 deletions(-)\n> \n> diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp\n> index 0190f677e679..d1d4d85ebe76 100644\n> --- a/src/libcamera/pipeline/ipu3/ipu3.cpp\n> +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp\n> @@ -791,8 +791,7 @@ void IPU3CameraData::cancelPendingRequests()\n> \twhile (!pendingRequests_.empty()) {\n> \t\tRequest *request = pendingRequests_.front();\n> \n> -\t\tfor (auto it : request->buffers()) {\n> -\t\t\tFrameBuffer *buffer = it.second;\n> +\t\tfor (auto [stream, buffer] : request->buffers()) {\n\nI think it might be better to default to `const auto&` as a rule of thumb to avoid copies.\n\nAnd I can also see a couple other hits for `for (const auto &it` and `for (auto const &it`,\nthose might also be worth converting.\n\n\nReviewed-by: Barnabás Pőcze \n\n\n> \t\t\tbuffer->_d()->cancel();\n> \t\t\tpipe()->completeBuffer(request, buffer);\n> \t\t}\n> @@ -1225,10 +1224,7 @@ void IPU3CameraData::paramsComputed(unsigned int id)\n> \t\treturn;\n> \n> \t/* Queue all buffers from the request aimed for the ImgU. */\n> -\tfor (auto it : info->request->buffers()) {\n> -\t\tconst Stream *stream = it.first;\n> -\t\tFrameBuffer *outbuffer = it.second;\n> -\n> +\tfor (auto [stream, outbuffer] : info->request->buffers()) {\n> \t\tif (stream == &outStream_)\n> \t\t\timgu_->output_->queueBuffer(outbuffer);\n> \t\telse if (stream == &vfStream_)\n> @@ -1304,8 +1300,7 @@ void IPU3CameraData::cio2BufferReady(FrameBuffer *buffer)\n> \n> \t/* If the buffer is cancelled force a complete of the whole request. */\n> \tif (buffer->metadata().status == FrameMetadata::FrameCancelled) {\n> -\t\tfor (auto it : request->buffers()) {\n> -\t\t\tFrameBuffer *b = it.second;\n> +\t\tfor (auto [stream, b] : request->buffers()) {\n> \t\t\tb->_d()->cancel();\n> \t\t\tpipe()->completeBuffer(request, b);\n> \t\t}\n> diff --git a/src/libcamera/pipeline/vimc/vimc.cpp b/src/libcamera/pipeline/vimc/vimc.cpp\n> index 4a03c149a617..025e7dbdd26f 100644\n> --- a/src/libcamera/pipeline/vimc/vimc.cpp\n> +++ b/src/libcamera/pipeline/vimc/vimc.cpp\n> @@ -607,8 +607,7 @@ void VimcCameraData::imageBufferReady(FrameBuffer *buffer)\n> \n> \t/* If the buffer is cancelled force a complete of the whole request. */\n> \tif (buffer->metadata().status == FrameMetadata::FrameCancelled) {\n> -\t\tfor (auto it : request->buffers()) {\n> -\t\t\tFrameBuffer *b = it.second;\n> +\t\tfor (auto [stream, b] : request->buffers()) {\n> \t\t\tb->_d()->cancel();\n> \t\t\tpipe->completeBuffer(request, b);\n> \t\t}\n> diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp\n> index 25b61d049a0e..02c50886a084 100644\n> --- a/src/libcamera/v4l2_videodevice.cpp\n> +++ b/src/libcamera/v4l2_videodevice.cpp\n> @@ -2042,10 +2042,8 @@ int V4L2VideoDevice::streamOff()\n> \tstate_ = State::Stopping;\n> \n> \t/* Send back all queued buffers. */\n> -\tfor (auto it : queuedBuffers_) {\n> -\t\tFrameBuffer *buffer = it.second;\n> -\n> -\t\tcache_->put(it.first);\n> +\tfor (auto [id, buffer] : queuedBuffers_) {\n> +\t\tcache_->put(id);\n> \t\tbuffer->_d()->cancel();\n> \t\tbufferReady.emit(buffer);\n> \t}\n> \n> base-commit: 1dcf9957a47fb54fce4fbae9daec0b587e52562e","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 945F3BDE6B\n\tfor ;\n\tThu, 12 Feb 2026 12:49:30 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 42103621CA;\n\tThu, 12 Feb 2026 13:49:30 +0100 (CET)","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 4ADDB62181\n\tfor ;\n\tThu, 12 Feb 2026 13:49:29 +0100 (CET)","from [192.168.33.66] (185.221.141.206.nat.pool.zt.hu\n\t[185.221.141.206])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 65AE8E70;\n\tThu, 12 Feb 2026 13:48:41 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; 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