[{"id":1336,"web_url":"https://patchwork.libcamera.org/comment/1336/","msgid":"<20190414202613.GN1980@bigcity.dyn.berto.se>","date":"2019-04-14T20:26:13","subject":"Re: [libcamera-devel] [PATCH v4 09/12] libcamera: buffer: Store\n\tRequest reference in Buffer","submitter":{"id":5,"url":"https://patchwork.libcamera.org/api/people/5/","name":"Niklas Söderlund","email":"niklas.soderlund@ragnatech.se"},"content":"Hi Jacopo,\n\nThanks for your work.\n\nOn 2019-04-09 21:25:45 +0200, Jacopo Mondi wrote:\n> Add to the Buffer class methods to set and retrieve a reference to the\n> Request instance this buffer is part of.\n> \n> As Buffers might outlive the Request they are associated with, the\n> reference is only temporarly valid during the buffer completion interval\n> (since when the buffer gets queued to Camera for processing, until it\n> gets marked as completed).\n\nI do not like this as the new functions are visible both to applications \nand pipeline handlers where we really should make the API fool proof. \nLooking a head in the series I do not like how this is used neither.\n\nSomething like this might be needed depending on outcome of discussions\nlater patches in this series. The patch itself is proper and if I agreed \nthat it was needed and/or that the usage of it later I would have \nattached by tag. For now I'm withholding it pending discussion.\n\n> \n> Signed-off-by: Jacopo Mondi \n> ---\n> include/libcamera/buffer.h | 5 +++++\n> src/libcamera/buffer.cpp | 39 +++++++++++++++++++++++++++++++++++++-\n> src/libcamera/request.cpp | 4 ++++\n> 3 files changed, 47 insertions(+), 1 deletion(-)\n> \n> diff --git a/include/libcamera/buffer.h b/include/libcamera/buffer.h\n> index 0c844d126a27..10c46cd57ab0 100644\n> --- a/include/libcamera/buffer.h\n> +++ b/include/libcamera/buffer.h\n> @@ -13,6 +13,7 @@\n> namespace libcamera {\n> \n> class BufferPool;\n> +class Request;\n> \n> class Plane final\n> {\n> @@ -53,6 +54,9 @@ public:\n> \tStatus status() const { return status_; }\n> \tstd::vector &planes() { return planes_; }\n> \n> +\tvoid setRequest(Request *req) { request_ = req; }\n> +\tRequest *request() const { return request_; }\n> +\n> private:\n> \tfriend class BufferPool;\n> \tfriend class PipelineHandler;\n> @@ -67,6 +71,7 @@ private:\n> \tStatus status_;\n> \n> \tstd::vector planes_;\n> +\tRequest *request_;\n> };\n> \n> class BufferPool final\n> diff --git a/src/libcamera/buffer.cpp b/src/libcamera/buffer.cpp\n> index e2d1cf04411e..68738b733ba6 100644\n> --- a/src/libcamera/buffer.cpp\n> +++ b/src/libcamera/buffer.cpp\n> @@ -196,7 +196,7 @@ void *Plane::mem()\n> */\n> \n> Buffer::Buffer()\n> -\t: index_(-1)\n> +\t: index_(-1), request_(nullptr)\n> {\n> }\n> \n> @@ -248,6 +248,43 @@ Buffer::Buffer()\n> * \\return The buffer status\n> */\n> \n> +/**\n> + * \\fn Buffer::setRequest()\n> + * \\brief Set the request this buffer belongs to\n> + *\n> + * Buffers are associated to Streams in a Request, which is then sent to the\n> + * Camera for processing. This method stores in the Buffer a pointer to the\n> + * Request this Buffer is part of, for later retrieval through the\n> + * Buffer::request() method.\n> + *\n> + * Buffers are associated to requests at Request::prepare() time and said\n> + * association is valid until the buffer does not complete at\n> + * Request::completeBuffer() time. Before and after the buffer completion\n> + * interval (the time between when the request is queued to the Camera, and\n> + * the buffer is marked as 'complete' by pipeline handlers) the reference to\n> + * Request is set to nullptr.\n> + */\n> +\n> +/**\n> + * \\fn Buffer::request()\n> + * \\brief Retrieve the request this buffer belongs to\n> + *\n> + * The intended callers of this method are buffer completion slots\n> + * implemented in CameraData sub-classes which needs to associated a request\n> + * to the just completed buffer, before calling Request::completeBuffer().\n> + *\n> + * It is up to the caller of this function to deal with the case the buffer has\n> + * been already marked as complete, and the reference to the Request has been\n> + * invalidated and set to nullptr.\n> + *\n> + * See also Buffer::setRequest() for a more detailed explanation of the\n> + * validity interval of the Request reference contained in a Buffer.\n> + *\n> + * \\return The Request this Buffer belongs to or nullptr if the Buffer has\n> + * not been queued to the Camera for processing yet or it has completed already.\n> + * \\sa Buffer::setRequest()\n> + */\n> +\n> /**\n> * \\brief Mark a buffer as cancel by setting its status to BufferCancelled\n> */\n> diff --git a/src/libcamera/request.cpp b/src/libcamera/request.cpp\n> index 3e10c995a6fa..7d80c635fa92 100644\n> --- a/src/libcamera/request.cpp\n> +++ b/src/libcamera/request.cpp\n> @@ -130,6 +130,8 @@ int Request::prepare()\n> {\n> \tfor (auto const &pair : bufferMap_) {\n> \t\tBuffer *buffer = pair.second;\n> +\n> +\t\tbuffer->setRequest(this);\n> \t\tpending_.insert(buffer);\n> \t}\n> \n> @@ -166,6 +168,8 @@ bool Request::completeBuffer(Buffer *buffer)\n> \tint ret = pending_.erase(buffer);\n> \tASSERT(ret == 1);\n> \n> +\tbuffer->setRequest(nullptr);\n> +\n> \treturn empty();\n> }\n> \n> -- \n> 2.21.0\n> \n> _______________________________________________\n> libcamera-devel mailing list\n> libcamera-devel@lists.libcamera.org\n> https://lists.libcamera.org/listinfo/libcamera-devel","headers":{"Return-Path":"","Received":["from mail-lj1-x22f.google.com (mail-lj1-x22f.google.com\n\t[IPv6:2a00:1450:4864:20::22f])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 7F54860DBE\n\tfor ;\n\tSun, 14 Apr 2019 22:26:15 +0200 (CEST)","by mail-lj1-x22f.google.com with SMTP id f18so13644206lja.10\n\tfor ;\n\tSun, 14 Apr 2019 13:26:15 -0700 (PDT)","from localhost (89-233-230-99.cust.bredband2.com. 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