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{ "id": 11805, "url": "https://patchwork.libcamera.org/api/1.1/patches/11805/?format=api", "web_url": "https://patchwork.libcamera.org/patch/11805/", "project": { "id": 1, "url": "https://patchwork.libcamera.org/api/1.1/projects/1/?format=api", "name": "libcamera", "link_name": "libcamera", "list_id": "libcamera_core", "list_email": "libcamera-devel@lists.libcamera.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20210401034648.136223-1-paul.elder@ideasonboard.com>", "date": "2021-04-01T03:46:48", "name": "[libcamera-devel,RFC] libcamera: Request: Add setHalfLife", "commit_ref": null, "pull_url": null, "state": "not-applicable", "archived": false, "hash": "8ef11de0fe1e8412a10b066401ecdc645a42fa5c", "submitter": { "id": 17, "url": "https://patchwork.libcamera.org/api/1.1/people/17/?format=api", "name": "Paul Elder", "email": "paul.elder@ideasonboard.com" }, "delegate": null, "mbox": "https://patchwork.libcamera.org/patch/11805/mbox/", "series": [ { "id": 1877, "url": "https://patchwork.libcamera.org/api/1.1/series/1877/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=1877", "date": "2021-04-01T03:46:48", "name": "[libcamera-devel,RFC] libcamera: Request: Add setHalfLife", "version": 1, "mbox": "https://patchwork.libcamera.org/series/1877/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/patches/11805/comments/", "check": "pending", "checks": "https://patchwork.libcamera.org/api/patches/11805/checks/", "tags": {}, "headers": { "Return-Path": "<libcamera-devel-bounces@lists.libcamera.org>", "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 2C805C0DA3\n\tfor <parsemail@patchwork.libcamera.org>;\n\tThu, 1 Apr 2021 03:48:05 +0000 (UTC)", "from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 8081E60517;\n\tThu, 1 Apr 2021 05:48:04 +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 37535602D2\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tThu, 1 Apr 2021 05:48:03 +0200 (CEST)", "from pyrite.rasen.tech (unknown\n\t[IPv6:2400:4051:61:600:2c71:1b79:d06d:5032])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 748A8F7;\n\tThu, 1 Apr 2021 05:48:01 +0200 (CEST)" ], "Authentication-Results": "lancelot.ideasonboard.com;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"nel92CdJ\"; dkim-atps=neutral", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1617248882;\n\tbh=+hQgYehDOuvzIjJH9GixvuUGRe8PHgnclfsALsdws5s=;\n\th=From:To:Cc:Subject:Date:From;\n\tb=nel92CdJn8AvUSXSTo6Nx4BkndalEfXiaadaLPGQbdrG7OVzDjyafcjK7ALf3Xq3D\n\twqo4fowh8CQkVV0RyQXebH7aLG+t60SNuuD6Z0FyR/sUiL0yoWBy2iZgLKKhZ9PIYK\n\tJK9u0GW82CmRBqehl9+O7tO1+RXcILz3xmG9b3SY=", "From": "Paul Elder <paul.elder@ideasonboard.com>", "To": "libcamera-devel@lists.libcamera.org", "Date": "Thu, 1 Apr 2021 12:46:48 +0900", "Message-Id": "<20210401034648.136223-1-paul.elder@ideasonboard.com>", "X-Mailer": "git-send-email 2.27.0", "MIME-Version": "1.0", "Subject": "[libcamera-devel] [RFC PATCH] libcamera: Request: Add setHalfLife", "X-BeenThere": "libcamera-devel@lists.libcamera.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "<libcamera-devel.lists.libcamera.org>", "List-Unsubscribe": "<https://lists.libcamera.org/options/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=unsubscribe>", "List-Archive": "<https://lists.libcamera.org/pipermail/libcamera-devel/>", "List-Post": "<mailto:libcamera-devel@lists.libcamera.org>", "List-Help": "<mailto:libcamera-devel-request@lists.libcamera.org?subject=help>", "List-Subscribe": "<https://lists.libcamera.org/listinfo/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=subscribe>", "Content-Type": "text/plain; charset=\"us-ascii\"", "Content-Transfer-Encoding": "7bit", "Errors-To": "libcamera-devel-bounces@lists.libcamera.org", "Sender": "\"libcamera-devel\" <libcamera-devel-bounces@lists.libcamera.org>" }, "content": "From the perspective of a Buffer, a Request can suddenly become nullptr\nin the middle of a stream. As Requests are supposed to be atomic, and\nthey are the nucleus of the libcamera camera streaming API, it would be\nconvenient if we could set the rate of decay of Requests.\n\nAdd a half life member variable to Request, and a setHalfLife() member\nfunction to set this. This will affect whether the Request is reusable\nor not, so Request::reuse() can now fail.\n\nSigned-off-by: Paul Elder <paul.elder@ideasonboard.com>\n\n---\nTODO: change the applications to reuse the request if reuse() fails\n---\n include/libcamera/request.h | 8 +++++++-\n src/libcamera/request.cpp | 36 ++++++++++++++++++++++++++++++++++--\n 2 files changed, 41 insertions(+), 3 deletions(-)", "diff": "diff --git a/include/libcamera/request.h b/include/libcamera/request.h\nindex 4cf5ff3f..45c707f3 100644\n--- a/include/libcamera/request.h\n+++ b/include/libcamera/request.h\n@@ -7,6 +7,7 @@\n #ifndef __LIBCAMERA_REQUEST_H__\n #define __LIBCAMERA_REQUEST_H__\n \n+#include <chrono>\n #include <map>\n #include <memory>\n #include <stdint.h>\n@@ -43,7 +44,7 @@ public:\n \tRequest(Camera *camera, uint64_t cookie = 0);\n \t~Request();\n \n-\tvoid reuse(ReuseFlag flags = Default);\n+\tbool reuse(ReuseFlag flags = Default);\n \n \tControlList &controls() { return *controls_; }\n \tControlList &metadata() { return *metadata_; }\n@@ -57,6 +58,8 @@ public:\n \n \tbool hasPendingBuffers() const { return !pending_.empty(); }\n \n+\tvoid setHalfLife(std::chrono::duration<double> hl);\n+\n \tstd::string toString() const;\n \n private:\n@@ -79,6 +82,9 @@ private:\n \tconst uint64_t cookie_;\n \tStatus status_;\n \tbool cancelled_;\n+\n+\tstd::chrono::steady_clock::time_point birthTime_;\n+\tstd::chrono::duration<double> halfLife_;\n };\n \n } /* namespace libcamera */\ndiff --git a/src/libcamera/request.cpp b/src/libcamera/request.cpp\nindex ce2dd7b1..0543abaf 100644\n--- a/src/libcamera/request.cpp\n+++ b/src/libcamera/request.cpp\n@@ -7,7 +7,9 @@\n \n #include <libcamera/request.h>\n \n+#include <chrono>\n #include <map>\n+#include <random>\n #include <sstream>\n \n #include <libcamera/buffer.h>\n@@ -74,7 +76,9 @@ LOG_DEFINE_CATEGORY(Request)\n */\n Request::Request(Camera *camera, uint64_t cookie)\n \t: camera_(camera), sequence_(0), cookie_(cookie),\n-\t status_(RequestPending), cancelled_(false)\n+\t status_(RequestPending), cancelled_(false),\n+\t birthTime_(std::chrono::steady_clock::now()),\n+\t halfLife_(std::chrono::seconds(10))\n {\n \t/**\n \t * \\todo Should the Camera expose a validator instance, to avoid\n@@ -111,11 +115,28 @@ Request::~Request()\n * prior to queueing the request to the camera, in lieu of constructing a new\n * request. The application can reuse the buffers that were previously added\n * to the request via addBuffer() by setting \\a flags to ReuseBuffers.\n+ *\n+ * The request for reuse may fail, as Requests can decay based on the half\n+ * life.\n+ *\n+ * \\return True on success, false otherwise\n */\n-void Request::reuse(ReuseFlag flags)\n+bool Request::reuse(ReuseFlag flags)\n {\n \tLIBCAMERA_TRACEPOINT(request_reuse, this);\n \n+\tstd::chrono::steady_clock::time_point end =\n+\t\tstd::chrono::steady_clock::now();\n+\tstd::chrono::duration<double> diff = end - birthTime_;\n+\n+\tstd::random_device rd{};\n+\tstd::mt19937 gen{ rd() };\n+\tdouble hlns =\n+\t\tstd::chrono::duration_cast<std::chrono::nanoseconds>(halfLife_).count();\n+\tstd::normal_distribution<> dist{ hlns, hlns / 2 };\n+\tif (dist(gen) > hlns)\n+\t\treturn false;\n+\n \tpending_.clear();\n \tif (flags & ReuseBuffers) {\n \t\tfor (auto pair : bufferMap_) {\n@@ -133,6 +154,8 @@ void Request::reuse(ReuseFlag flags)\n \n \tcontrols_->clear();\n \tmetadata_->clear();\n+\n+\treturn true;\n }\n \n /**\n@@ -320,6 +343,15 @@ bool Request::completeBuffer(FrameBuffer *buffer)\n \treturn !hasPendingBuffers();\n }\n \n+/**\n+ * \\brief Set the half life of the request\n+ * \\param[in] hl Half-life of the request\n+ */\n+void Request::setHalfLife(std::chrono::duration<double> hl)\n+{\n+\thalfLife_ = hl;\n+}\n+\n /**\n * \\brief Generate a string representation of the Request internals\n *\n", "prefixes": [ "libcamera-devel", "RFC" ] }