{"id":9089,"url":"https://patchwork.libcamera.org/api/patches/9089/?format=json","web_url":"https://patchwork.libcamera.org/patch/9089/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20200731133947.84258-3-email@uajain.com>","date":"2020-07-31T13:39:55","name":"[libcamera-devel,v3,2/3] libcamera: object: Add deleteLater() support","commit_ref":null,"pull_url":null,"state":"accepted","archived":false,"hash":"2d6722cecece2575dae14fd41b42c1883441be41","submitter":{"id":1,"url":"https://patchwork.libcamera.org/api/people/1/?format=json","name":"Umang Jain","email":"email@uajain.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/9089/mbox/","series":[{"id":1168,"url":"https://patchwork.libcamera.org/api/series/1168/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=1168","date":"2020-07-31T13:39:52","name":"Add Object::deleteLater() support","version":3,"mbox":"https://patchwork.libcamera.org/series/1168/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/9089/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/9089/checks/","tags":{},"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 61267BD878\n\tfor ;\n\tFri, 31 Jul 2020 13:39:59 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 2F85C61ED2;\n\tFri, 31 Jul 2020 15:39:59 +0200 (CEST)","from o1.f.az.sendgrid.net (o1.f.az.sendgrid.net [208.117.55.132])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id D133F616FF\n\tfor ;\n\tFri, 31 Jul 2020 15:39:56 +0200 (CEST)","by filterdrecv-p3mdw1-7ff865655c-hpdqc with SMTP id\n\tfilterdrecv-p3mdw1-7ff865655c-hpdqc-19-5F241F2B-25\n\t2020-07-31 13:39:55.564770342 +0000 UTC m=+156224.759476860","from mail.uajain.com (unknown)\n\tby ismtpd0005p1maa1.sendgrid.net (SG) with ESMTP\n\tid mQXGQXJBQDqYv704DpU31Q Fri, 31 Jul 2020 13:39:54.679 +0000 (UTC)"],"Authentication-Results":"lancelot.ideasonboard.com;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n\tunprotected) header.d=uajain.com header.i=@uajain.com\n\theader.b=\"bzez5/Wr\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=uajain.com;\n\th=from:subject:in-reply-to:references:mime-version:to:cc:\n\tcontent-transfer-encoding:content-type;\n\ts=s1; bh=MGQPbAd0XKQDUt1FWMgX/SrB2ThHIz3/DdC4y9z43Y0=;\n\tb=bzez5/Wr5Y24p/0Tq4D6HXf1JOip9Orb9OAhMZTFUZh/mHVp7DGz+wBuAlhSSbZ4gD9Y\n\tnC2VXEH1nkq2sMov9m5KHCs20j1j7NFJBGc7ty+dsspwRHSdVlvBaDQHLMh16/Cw8rAEX3\n\tTBRVWPy7+RpRRNogXPNm7WRzFzppxzq70=","From":"Umang Jain ","Date":"Fri, 31 Jul 2020 13:39:55 +0000 (UTC)","Message-Id":"<20200731133947.84258-3-email@uajain.com>","In-Reply-To":"<20200731133947.84258-1-email@uajain.com>","References":"<20200731133947.84258-1-email@uajain.com>","Mime-Version":"1.0","X-SG-EID":"1Q40EQ7YGir8a9gjSIAdTjhngY657NMk9ckeo4dbHZDiOpywc/L3L9rFqlwE4KPcu2AmDZxpR9j2S9uUCg9Ys7krDPmWy2OqGnsRcgal8sKxTv5UymibaUbsW/VyAEP3afoHjebEFcdoq9MaUEQ8Vjg2pT6uEzAwz8VC3pVmHhnIHavlLtoAFaZIIKh/LrmDc3CL7P59uC2Ww54f0zJ/t9hbwnFxIQJ9DIVzssOmx71A7rSaY3zYv8X+oOPFhaNRIKOMc95GpJJHUc+5nnBy8w==","To":"libcamera-devel@lists.libcamera.org","Subject":"[libcamera-devel] [PATCH v3 2/3] libcamera: object: Add\n\tdeleteLater() support","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","Content-Type":"text/plain; charset=\"us-ascii\"","Content-Transfer-Encoding":"7bit","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"This commit adds support to schedule the deletion of an Object to the\nthread it is bound to (similar to [1]). An Object getting destroyed\nby a different thread is considered as a violation as per the\nlibcamera threading model.\n\nThis will be useful for an Object where its ownership is shared via\nshared pointers in different threads. If the thread which drops the\nlast reference of the Object is a different thread, the destructors\nget called in that particular thread, not the one Object is bound to.\nHence, in order to resolve this kind of situation, the creation of\nshared pointer can be accompanied by a custom deleter which in turns\nuse deleteLater() to ensure the Object is destroyed in its own thread.\n\n[1] https://doc.qt.io/qt-5/qobject.html#deleteLater\n\nSigned-off-by: Umang Jain \nReviewed-by: Laurent Pinchart \n---\n include/libcamera/internal/message.h | 1 +\n include/libcamera/object.h | 2 +\n src/libcamera/message.cpp | 2 +\n src/libcamera/object.cpp | 48 ++++++++++\n test/meson.build | 1 +\n test/object-delete.cpp | 125 +++++++++++++++++++++++++++\n 6 files changed, 179 insertions(+)\n create mode 100644 test/object-delete.cpp","diff":"diff --git a/include/libcamera/internal/message.h b/include/libcamera/internal/message.h\nindex 92ea64a..98e5a28 100644\n--- a/include/libcamera/internal/message.h\n+++ b/include/libcamera/internal/message.h\n@@ -25,6 +25,7 @@ public:\n \t\tNone = 0,\n \t\tInvokeMessage = 1,\n \t\tThreadMoveMessage = 2,\n+\t\tDeferredDelete=3,\n \t\tUserMessage = 1000,\n \t};\n \ndiff --git a/include/libcamera/object.h b/include/libcamera/object.h\nindex 9a3dd07..a1882f0 100644\n--- a/include/libcamera/object.h\n+++ b/include/libcamera/object.h\n@@ -27,6 +27,8 @@ public:\n \tObject(Object *parent = nullptr);\n \tvirtual ~Object();\n \n+\tvoid deleteLater();\n+\n \tvoid postMessage(std::unique_ptr msg);\n \n \ttemplateparent_ = nullptr;\n }\n \n+/**\n+ * \\brief Schedule deletion of the instance in the thread it belongs to\n+ *\n+ * This function schedules deletion of the Object when control returns to the\n+ * event loop that the object belongs to. This ensures the object is destroyed\n+ * from the right context, as required by the libcamera threading model.\n+ *\n+ * If this function is called before the thread's event loop is started, the\n+ * object will be deleted when the event loop starts.\n+ *\n+ * Deferred deletion can be used to control the destruction context with shared\n+ * pointers. An object managed with shared pointers is deleted when the last\n+ * reference is destroyed, which makes difficult to ensure through software\n+ * design which context the deletion will take place in. With a custom deleter\n+ * for the shared pointer using deleteLater(), the deletion can be guaranteed to\n+ * happen in the thread the object is bound to.\n+ *\n+ * \\code{.cpp}\n+ * std::shared_ptr createObject()\n+ * {\n+ * struct Deleter : std::default_delete {\n+ * void operator()(MyObject *obj)\n+ * {\n+ * delete obj;\n+ * }\n+ * };\n+ *\n+ * MyObject *obj = new MyObject();\n+ *\n+ * return std::shared_ptr(obj, Deleter());\n+ * }\n+ * \\endcode\n+ *\n+ * \\context This function is \\threadsafe.\n+ */\n+void Object::deleteLater()\n+{\n+ postMessage(std::make_unique(Message::DeferredDelete));\n+}\n+\n /**\n * \\brief Post a message to the object's thread\n * \\param[in] msg The message\n@@ -144,6 +188,10 @@ void Object::message(Message *msg)\n \t\tbreak;\n \t}\n \n+\tcase Message::DeferredDelete:\n+\t\tdelete this;\n+\t\tbreak;\n+\n \tdefault:\n \t\tbreak;\n \t}\ndiff --git a/test/meson.build b/test/meson.build\nindex f41d6e7..f5aa144 100644\n--- a/test/meson.build\n+++ b/test/meson.build\n@@ -34,6 +34,7 @@ internal_tests = [\n ['hotplug-cameras', 'hotplug-cameras.cpp'],\n ['message', 'message.cpp'],\n ['object', 'object.cpp'],\n+ ['object-delete', 'object-delete.cpp'],\n ['object-invoke', 'object-invoke.cpp'],\n ['pixel-format', 'pixel-format.cpp'],\n ['signal-threads', 'signal-threads.cpp'],\ndiff --git a/test/object-delete.cpp b/test/object-delete.cpp\nnew file mode 100644\nindex 0000000..6cd1a1e\n--- /dev/null\n+++ b/test/object-delete.cpp\n@@ -0,0 +1,125 @@\n+/* SPDX-License-Identifier: GPL-2.0-or-later */\n+/*\n+ * Copyright (C) 2020, Umang Jain \n+ *\n+ * object.cpp - Object deletion tests\n+ */\n+\n+#include \n+\n+#include \n+#include \n+\n+#include \"libcamera/internal/thread.h\"\n+\n+#include \"test.h\"\n+\n+using namespace std;\n+using namespace libcamera;\n+\n+/*\n+ * Global flag to check if object is on its way to deletion from it's\n+ * own thread only.\n+ */\n+bool ObjectDeleted = false;\n+\n+class NewThread : public Thread\n+{\n+public:\n+\tNewThread(Object *obj = nullptr)\n+\t\t: object_(obj), deleteScheduled_(false)\n+\t{\n+\t}\n+\n+\tbool objectScheduledForDeletion() { return deleteScheduled_; }\n+\n+protected:\n+ void run()\n+ {\n+\t\tobject_->deleteLater();\n+\t\tdeleteScheduled_ = true;\n+ }\n+\n+private:\n+\tObject *object_;\n+\tbool deleteScheduled_;\n+};\n+\n+\n+class TestObject : public Object\n+{\n+public:\n+\tTestObject()\n+\t{\n+\t}\n+\n+\t~TestObject()\n+\t{\n+\t\tif (thread() == Thread::current())\n+\t\t\tObjectDeleted = true;\n+\t}\n+};\n+\n+class ObjectDeleteTest : public Test\n+{\n+protected:\n+\tint init()\n+\t{\n+\t\tisDeleteScheduled_ = false;\n+\n+\t\treturn 0;\n+\t}\n+\n+\tint run()\n+\t{\n+\t\tTestObject *obj;\n+\n+\t\tobj = new TestObject();\n+\t\tNewThread thread(obj);\n+\t\tthread.start();\n+\t\tTimer timer;\n+\t\ttimer.start(100);\n+\n+\t\twhile (timer.isRunning() && !isDeleteScheduled_)\n+\t\t\tisDeleteScheduled_ = thread.objectScheduledForDeletion();\n+\n+\t\tthread.exit();\n+\t\tthread.wait();\n+\n+\t\tif (!isDeleteScheduled_) {\n+\t\t\tcout << \"Failed to queue object for deletion from another thread\" << endl;\n+\t\t\treturn TestFail;\n+\t\t}\n+\n+\t\tThread::current()->dispatchMessages(Message::Type::DeferredDelete);\n+\n+\t\tif (!ObjectDeleted) {\n+\t\t\tcout << \"Failed to delete object queued from another thread\" << endl;\n+\t\t\treturn TestFail;\n+\t\t}\n+\n+\t\tObjectDeleted = false;\n+\t\tobj = new TestObject();\n+\t\tobj->deleteLater();\n+\t\t/*\n+\t\t * \\todo Devise a check for multiple deleteLater() calls to a object.\n+\t\t * It should be checked that the object is deleted only once.\n+\t\t */\n+\t\tThread::current()->dispatchMessages(Message::Type::DeferredDelete);\n+\t\tif(!ObjectDeleted) {\n+\t\t\tcout << \"Failed to delete object\";\n+\t\t\treturn TestFail;\n+\t\t}\n+\n+\t\treturn TestPass;\n+\t}\n+\n+\tvoid cleanup()\n+\t{\n+\t}\n+\n+private:\n+\tbool isDeleteScheduled_;\n+};\n+\n+TEST_REGISTER(ObjectDeleteTest)\n","prefixes":["libcamera-devel","v3","2/3"]}