[{"id":4209,"web_url":"https://patchwork.libcamera.org/comment/4209/","msgid":"<30e79ff1-8f87-9ec7-b88b-0eb6c92943ed@ideasonboard.com>","date":"2020-03-23T14:59:08","subject":"Re: [libcamera-devel] [PATCH 05/21] qcam: main_window: Move capture\n\tevent processing to main thread","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Hi Laurent,\n\nOn 23/03/2020 14:21, Laurent Pinchart wrote:\n> To avoid blocking the camera manager for a long amount of time, move\n> capture event processing to the main thread. Captured buffers are added\n> to a queue and an event is posted to the main window to signal\n> availability of a buffer.\n> \n\nIs the 'queue' necessary?\nCould the buffers not be passed through the event?\n\n> Signed-off-by: Laurent Pinchart \n> ---\n> src/qcam/main_window.cpp | 54 +++++++++++++++++++++++++++++++++++++++-\n> src/qcam/main_window.h | 8 ++++++\n> 2 files changed, 61 insertions(+), 1 deletion(-)\n> \n> diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp\n> index 354a53367d0f..afd8b9c413f5 100644\n> --- a/src/qcam/main_window.cpp\n> +++ b/src/qcam/main_window.cpp\n> @@ -19,6 +19,7 @@\n> #include \n> #include \n> #include \n> +#include \n> #include \n> #include \n> #include \n> @@ -31,6 +32,21 @@\n> \n> using namespace libcamera;\n> \n> +class CaptureEvent : public QEvent\n> +{\n> +public:\n> +\tCaptureEvent()\n> +\t\t: QEvent(type())\n> +\t{\n> +\t}\n> +\n> +\tstatic Type type()\n> +\t{\n> +\t\tstatic int type = QEvent::registerEventType();\n> +\t\treturn static_cast(type);\n> +\t}\n> +};\n> +\n> MainWindow::MainWindow(CameraManager *cm, const OptionsParser::Options &options)\n> \t: options_(options), cm_(cm), allocator_(nullptr), isCapturing_(false)\n> {\n> @@ -63,6 +79,16 @@ MainWindow::~MainWindow()\n> \t}\n> }\n> \n> +bool MainWindow::event(QEvent *e)\n> +{\n> +\tif (e->type() == CaptureEvent::type()) {\n> +\t\tprocessCapture();\n> +\t\treturn true;\n> +\t}\n> +\n> +\treturn QMainWindow::event(e);\n> +}\n> +\n> int MainWindow::createToolbars()\n> {\n> \tQAction *action;\n> @@ -343,6 +369,13 @@ void MainWindow::stopCapture()\n> \n> \tconfig_.reset();\n> \n> +\t/*\n> +\t * A CaptureEvent may have been posted before we stopped the camera,\n> +\t * but not processed yet. Clear the queue of done buffers to avoid\n> +\t * racing with the event handler.\n> +\t */\n> +\tdoneQueue_.clear();\n> +\n\nDo we not need to lock mutex_ here?\n\n> \ttitleTimer_.stop();\n> \tsetWindowTitle(title_);\n> }\n> @@ -371,10 +404,29 @@ void MainWindow::requestComplete(Request *request)\n> \t\treturn;\n> \n> \tconst std::map &buffers = request->buffers();\n> +\tFrameBuffer *buffer = buffers.begin()->second;\n> +\n> +\t{\n> +\t\tQMutexLocker locker(&mutex_);\n> +\t\tdoneQueue_.enqueue(buffer);\n> +\t}\n> +\n> +\tQCoreApplication::postEvent(this, new CaptureEvent);\n> +}\n> +\n> +void MainWindow::processCapture()\n> +{\n> +\tFrameBuffer *buffer;\n\nThis scoping is to ensure the locker unlocks after the dequeue right?\n\nPerhaps a new line between the FrameBuffer declaration and the start of\nthe scope? It looks a bit like some sort of badly defined inline\nfunction otherwise :-S\n\n> +\t{\n> +\t\tQMutexLocker locker(&mutex_);\n> +\t\tif (doneQueue_.isEmpty())\n> +\t\t\treturn;\n> +\n> +\t\tbuffer = doneQueue_.dequeue();\n> +\t}\n> \n> \tframesCaptured_++;\n> \n> -\tFrameBuffer *buffer = buffers.begin()->second;\n> \tconst FrameMetadata &metadata = buffer->metadata();\n> \n> \tdouble fps = metadata.timestamp - lastBufferTime_;\n> diff --git a/src/qcam/main_window.h b/src/qcam/main_window.h\n> index 720a3393e3dc..c623120d5894 100644\n> --- a/src/qcam/main_window.h\n> +++ b/src/qcam/main_window.h\n> @@ -11,7 +11,9 @@\n> \n> #include \n> #include \n> +#include \n> #include \n> +#include \n> #include \n> \n> #include \n> @@ -40,6 +42,8 @@ public:\n> \tMainWindow(CameraManager *cm, const OptionsParser::Options &options);\n> \t~MainWindow();\n> \n> +\tbool event(QEvent *e) override;\n> +\n> private Q_SLOTS:\n> \tvoid quit();\n> \tvoid updateTitle();\n> @@ -57,6 +61,7 @@ private:\n> \tint openCamera();\n> \n> \tvoid requestComplete(Request *request);\n> +\tvoid processCapture();\n> \tint display(FrameBuffer *buffer);\n> \tvoid queueRequest(FrameBuffer *buffer);\n> \n> @@ -78,6 +83,9 @@ private:\n> \tuint32_t previousFrames_;\n> \tuint32_t framesCaptured_;\n> \n> +\tQMutex mutex_;\n> +\tQQueue doneQueue_;\n> +\n> \tQToolBar *toolbar_;\n> \tViewFinder *viewfinder_;\n> \tstd::map> mappedBuffers_;\n>","headers":{"Return-Path":"","Received":["from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 634E960413\n\tfor ;\n\tMon, 23 Mar 2020 15:59:12 +0100 (CET)","from [192.168.0.20]\n\t(cpc89242-aztw30-2-0-cust488.18-1.cable.virginm.net [86.31.129.233])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id CF9C3308;\n\tMon, 23 Mar 2020 15:59:11 +0100 (CET)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1584975552;\n\tbh=SDKaLb9AUZzyJXX+zQWv90E+bZC2yIium954CXzcR8Q=;\n\th=Reply-To:Subject:To:References:From:Date:In-Reply-To:From;\n\tb=m3UgiILsgEjrL84oSuS0d4CTJeUc6RutNxXJl0puy6pqlFAH3zQ4j3uN1FhshoPS3\n\tyef2rMaJvL1hbRxrz5mcjW1ijLmeYW/OgHIREdEjmU9WEeT28ek4cWrIwWsbxD3O+y\n\t+1MM769nJnVxmU+KNx7VGPjGTsbWnGNJUXSXMRlY=","Reply-To":"kieran.bingham@ideasonboard.com","To":"Laurent Pinchart ,\n\tlibcamera-devel@lists.libcamera.org","References":"<20200323142205.28342-1-laurent.pinchart@ideasonboard.com>\n\t<20200323142205.28342-6-laurent.pinchart@ideasonboard.com>","From":"Kieran Bingham ","Openpgp":"preference=signencrypt","Autocrypt":"addr=kieran.bingham@ideasonboard.com; keydata=\n\tmQINBFYE/WYBEACs1PwjMD9rgCu1hlIiUA1AXR4rv2v+BCLUq//vrX5S5bjzxKAryRf0uHat\n\tV/zwz6hiDrZuHUACDB7X8OaQcwhLaVlq6byfoBr25+hbZG7G3+5EUl9cQ7dQEdvNj6V6y/SC\n\trRanWfelwQThCHckbobWiQJfK9n7rYNcPMq9B8e9F020LFH7Kj6YmO95ewJGgLm+idg1Kb3C\n\tpotzWkXc1xmPzcQ1fvQMOfMwdS+4SNw4rY9f07Xb2K99rjMwZVDgESKIzhsDB5GY465sCsiQ\n\tcSAZRxqE49RTBq2+EQsbrQpIc8XiffAB8qexh5/QPzCmR4kJgCGeHIXBtgRj+nIkCJPZvZtf\n\tKr2EAbc6tgg6DkAEHJb+1okosV09+0+TXywYvtEop/WUOWQ+zo+Y/OBd+8Ptgt1pDRyOBzL8\n\tRXa8ZqRf0Mwg75D+dKntZeJHzPRJyrlfQokngAAs4PaFt6UfS+ypMAF37T6CeDArQC41V3ko\n\tlPn1yMsVD0p+6i3DPvA/GPIksDC4owjnzVX9kM8Zc5Cx+XoAN0w5Eqo4t6qEVbuettxx55gq\n\t8K8FieAjgjMSxngo/HST8TpFeqI5nVeq0/lqtBRQKumuIqDg+Bkr4L1V/PSB6XgQcOdhtd36\n\tOe9X9dXB8YSNt7VjOcO7BTmFn/Z8r92mSAfHXpb07YJWJosQOQARAQABtDBLaWVyYW4gQmlu\n\tZ2hhbSA8a2llcmFuLmJpbmdoYW1AaWRlYXNvbmJvYXJkLmNvbT6JAlcEEwEKAEECGwMFCwkI\n\tBwIGFQgJCgsCBBYCAwECHgECF4ACGQEWIQSQLdeYP70o/eNy1HqhHkZyEKRh/QUCXWTtygUJ\n\tCyJXZAAKCRChHkZyEKRh/f8dEACTDsbLN2nioNZMwyLuQRUAFcXNolDX48xcUXsWS2QjxaPm\n\tVsJx8Uy8aYkS85mdPBh0C83OovQR/OVbr8AxhGvYqBs3nQvbWuTl/+4od7DfK2VZOoKBAu5S\n\tQK2FYuUcikDqYcFWJ8DQnubxfE8dvzojHEkXw0sA4igINHDDFX3HJGZtLio+WpEFQtCbfTAG\n\tYZslasz1YZRbwEdSsmO3/kqy5eMnczlm8a21A3fKUo3g8oAZEFM+f4DUNzqIltg31OAB/kZS\n\tenKZQ/SWC8PmLg/ZXBrReYakxXtkP6w3FwMlzOlhGxqhIRNiAJfXJBaRhuUWzPOpEDE9q5YJ\n\tBmqQL2WJm1VSNNVxbXJHpaWMH1sA2R00vmvRrPXGwyIO0IPYeUYQa3gsy6k+En/aMQJd27dp\n\taScf9am9PFICPY5T4ppneeJLif2lyLojo0mcHOV+uyrds9XkLpp14GfTkeKPdPMrLLTsHRfH\n\tfA4I4OBpRrEPiGIZB/0im98MkGY/Mu6qxeZmYLCcgD6qz4idOvfgVOrNh+aA8HzIVR+RMW8H\n\tQGBN9f0E3kfwxuhl3omo6V7lDw8XOdmuWZNC9zPq1UfryVHANYbLGz9KJ4Aw6M+OgBC2JpkD\n\thXMdHUkC+d20dwXrwHTlrJi1YNp6rBc+xald3wsUPOZ5z8moTHUX/uPA/qhGsbkCDQRWBP1m\n\tARAAzijkb+Sau4hAncr1JjOY+KyFEdUNxRy+hqTJdJfaYihxyaj0Ee0P0zEi35CbE6lgU0Uz\n\ttih9fiUbSV3wfsWqg1Ut3/5rTKu7kLFp15kF7eqvV4uezXRD3Qu4yjv/rMmEJbbD4cTvGCYI\n\td6MDC417f7vK3hCbCVIZSp3GXxyC1LU+UQr3fFcOyCwmP9vDUR9JV0BSqHHxRDdpUXE26Dk6\n\tmhf0V1YkspE5St814ETXpEus2urZE5yJIUROlWPIL+hm3NEWfAP06vsQUyLvr/GtbOT79vXl\n\tEn1aulcYyu20dRRxhkQ6iILaURcxIAVJJKPi8dsoMnS8pB0QW12AHWuirPF0g6DiuUfPmrA5\n\tPKe56IGlpkjc8cO51lIxHkWTpCMWigRdPDexKX+Sb+W9QWK/0JjIc4t3KBaiG8O4yRX8ml2R\n\t+rxfAVKM6V769P/hWoRGdgUMgYHFpHGSgEt80OKK5HeUPy2cngDUXzwrqiM5Sz6Od0qw5pCk\n\tNlXqI0W/who0iSVM+8+RmyY0OEkxEcci7rRLsGnM15B5PjLJjh1f2ULYkv8s4SnDwMZ/kE04\n\t/UqCMK/KnX8pwXEMCjz0h6qWNpGwJ0/tYIgQJZh6bqkvBrDogAvuhf60Sogw+mH8b+PBlx1L\n\toeTK396wc+4c3BfiC6pNtUS5GpsPMMjYMk7kVvEAEQEAAYkCPAQYAQoAJgIbDBYhBJAt15g/\n\tvSj943LUeqEeRnIQpGH9BQJdizzIBQkLSKZiAAoJEKEeRnIQpGH9eYgQAJpjaWNgqNOnMTmD\n\tMJggbwjIotypzIXfhHNCeTkG7+qCDlSaBPclcPGYrTwCt0YWPU2TgGgJrVhYT20ierN8LUvj\n\t6qOPTd+Uk7NFzL65qkh80ZKNBFddx1AabQpSVQKbdcLb8OFs85kuSvFdgqZwgxA1vl4TFhNz\n\tPZ79NAmXLackAx3sOVFhk4WQaKRshCB7cSl+RIng5S/ThOBlwNlcKG7j7W2MC06BlTbdEkUp\n\tECzuuRBv8wX4OQl+hbWbB/VKIx5HKlLu1eypen/5lNVzSqMMIYkkZcjV2SWQyUGxSwq0O/sx\n\tS0A8/atCHUXOboUsn54qdxrVDaK+6jIAuo8JiRWctP16KjzUM7MO0/+4zllM8EY57rXrj48j\n\tsbEYX0YQnzaj+jO6kJtoZsIaYR7rMMq9aUAjyiaEZpmP1qF/2sYenDx0Fg2BSlLvLvXM0vU8\n\tpQk3kgDu7kb/7PRYrZvBsr21EIQoIjXbZxDz/o7z95frkP71EaICttZ6k9q5oxxA5WC6sTXc\n\tMW8zs8avFNuA9VpXt0YupJd2ijtZy2mpZNG02fFVXhIn4G807G7+9mhuC4XG5rKlBBUXTvPU\n\tAfYnB4JBDLmLzBFavQfvonSfbitgXwCG3vS+9HEwAjU30Bar1PEOmIbiAoMzuKeRm2LVpmq4\n\tWZw01QYHU/GUV/zHJSFk","Organization":"Ideas on Board","Message-ID":"<30e79ff1-8f87-9ec7-b88b-0eb6c92943ed@ideasonboard.com>","Date":"Mon, 23 Mar 2020 14:59:08 +0000","User-Agent":"Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101\n\tThunderbird/60.9.1","MIME-Version":"1.0","In-Reply-To":"<20200323142205.28342-6-laurent.pinchart@ideasonboard.com>","Content-Type":"text/plain; charset=utf-8","Content-Language":"en-GB","Content-Transfer-Encoding":"8bit","Subject":"Re: [libcamera-devel] [PATCH 05/21] qcam: main_window: Move capture\n\tevent processing to main thread","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","X-List-Received-Date":"Mon, 23 Mar 2020 14:59:12 -0000"}},{"id":4230,"web_url":"https://patchwork.libcamera.org/comment/4230/","msgid":"<20200323165256.GQ4768@pendragon.ideasonboard.com>","date":"2020-03-23T16:52:56","subject":"Re: [libcamera-devel] [PATCH 05/21] qcam: main_window: Move capture\n\tevent processing to main thread","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"content":"Hi Kieran,\n\nOn Mon, Mar 23, 2020 at 02:59:08PM +0000, Kieran Bingham wrote:\n> On 23/03/2020 14:21, Laurent Pinchart wrote:\n> > To avoid blocking the camera manager for a long amount of time, move\n> > capture event processing to the main thread. Captured buffers are added\n> > to a queue and an event is posted to the main window to signal\n> > availability of a buffer.\n> \n> Is the 'queue' necessary?\n> Could the buffers not be passed through the event?\n\nI would then have no way in processCapture() to ignore the event after\nstopping the camera. I could check isCapturing_, but at least in theory,\nwe could stop and restart and have the pending event generated before\nstopped delivered after the restart. I think a queue is cleaner as it\ngives us full control.\n\n> > Signed-off-by: Laurent Pinchart \n> > ---\n> > src/qcam/main_window.cpp | 54 +++++++++++++++++++++++++++++++++++++++-\n> > src/qcam/main_window.h | 8 ++++++\n> > 2 files changed, 61 insertions(+), 1 deletion(-)\n> > \n> > diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp\n> > index 354a53367d0f..afd8b9c413f5 100644\n> > --- a/src/qcam/main_window.cpp\n> > +++ b/src/qcam/main_window.cpp\n> > @@ -19,6 +19,7 @@\n> > #include \n> > #include \n> > #include \n> > +#include \n> > #include \n> > #include \n> > #include \n> > @@ -31,6 +32,21 @@\n> > \n> > using namespace libcamera;\n> > \n> > +class CaptureEvent : public QEvent\n> > +{\n> > +public:\n> > +\tCaptureEvent()\n> > +\t\t: QEvent(type())\n> > +\t{\n> > +\t}\n> > +\n> > +\tstatic Type type()\n> > +\t{\n> > +\t\tstatic int type = QEvent::registerEventType();\n> > +\t\treturn static_cast(type);\n> > +\t}\n> > +};\n> > +\n> > MainWindow::MainWindow(CameraManager *cm, const OptionsParser::Options &options)\n> > \t: options_(options), cm_(cm), allocator_(nullptr), isCapturing_(false)\n> > {\n> > @@ -63,6 +79,16 @@ MainWindow::~MainWindow()\n> > \t}\n> > }\n> > \n> > +bool MainWindow::event(QEvent *e)\n> > +{\n> > +\tif (e->type() == CaptureEvent::type()) {\n> > +\t\tprocessCapture();\n> > +\t\treturn true;\n> > +\t}\n> > +\n> > +\treturn QMainWindow::event(e);\n> > +}\n> > +\n> > int MainWindow::createToolbars()\n> > {\n> > \tQAction *action;\n> > @@ -343,6 +369,13 @@ void MainWindow::stopCapture()\n> > \n> > \tconfig_.reset();\n> > \n> > +\t/*\n> > +\t * A CaptureEvent may have been posted before we stopped the camera,\n> > +\t * but not processed yet. Clear the queue of done buffers to avoid\n> > +\t * racing with the event handler.\n> > +\t */\n> > +\tdoneQueue_.clear();\n> > +\n> \n> Do we not need to lock mutex_ here?\n\nNo, because at this point there can't be any call to\nMainWindow::requestComplete(), as the camera is stopped. This function,\nas well as MainWindow::processCapture(), run in the same thread, so they\ncan't run concurrently.\n\n> > \ttitleTimer_.stop();\n> > \tsetWindowTitle(title_);\n> > }\n> > @@ -371,10 +404,29 @@ void MainWindow::requestComplete(Request *request)\n> > \t\treturn;\n> > \n> > \tconst std::map &buffers = request->buffers();\n> > +\tFrameBuffer *buffer = buffers.begin()->second;\n> > +\n> > +\t{\n> > +\t\tQMutexLocker locker(&mutex_);\n> > +\t\tdoneQueue_.enqueue(buffer);\n> > +\t}\n> > +\n> > +\tQCoreApplication::postEvent(this, new CaptureEvent);\n> > +}\n> > +\n> > +void MainWindow::processCapture()\n> > +{\n> > +\tFrameBuffer *buffer;\n> \n> This scoping is to ensure the locker unlocks after the dequeue right?\n\nCorrect.\n\n> Perhaps a new line between the FrameBuffer declaration and the start of\n> the scope? It looks a bit like some sort of badly defined inline\n> function otherwise :-S\n\nOK.\n\n> > +\t{\n> > +\t\tQMutexLocker locker(&mutex_);\n> > +\t\tif (doneQueue_.isEmpty())\n> > +\t\t\treturn;\n> > +\n> > +\t\tbuffer = doneQueue_.dequeue();\n> > +\t}\n> > \n> > \tframesCaptured_++;\n> > \n> > -\tFrameBuffer *buffer = buffers.begin()->second;\n> > \tconst FrameMetadata &metadata = buffer->metadata();\n> > \n> > \tdouble fps = metadata.timestamp - lastBufferTime_;\n> > diff --git a/src/qcam/main_window.h b/src/qcam/main_window.h\n> > index 720a3393e3dc..c623120d5894 100644\n> > --- a/src/qcam/main_window.h\n> > +++ b/src/qcam/main_window.h\n> > @@ -11,7 +11,9 @@\n> > \n> > #include \n> > #include \n> > +#include \n> > #include \n> > +#include \n> > #include \n> > \n> > #include \n> > @@ -40,6 +42,8 @@ public:\n> > \tMainWindow(CameraManager *cm, const OptionsParser::Options &options);\n> > \t~MainWindow();\n> > \n> > +\tbool event(QEvent *e) override;\n> > +\n> > private Q_SLOTS:\n> > \tvoid quit();\n> > \tvoid updateTitle();\n> > @@ -57,6 +61,7 @@ private:\n> > \tint openCamera();\n> > \n> > \tvoid requestComplete(Request *request);\n> > +\tvoid processCapture();\n> > \tint display(FrameBuffer *buffer);\n> > \tvoid queueRequest(FrameBuffer *buffer);\n> > \n> > @@ -78,6 +83,9 @@ private:\n> > \tuint32_t previousFrames_;\n> > \tuint32_t framesCaptured_;\n> > \n> > +\tQMutex mutex_;\n> > +\tQQueue doneQueue_;\n> > +\n> > \tQToolBar *toolbar_;\n> > \tViewFinder *viewfinder_;\n> > \tstd::map> mappedBuffers_;","headers":{"Return-Path":"","Received":["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 8B46760417\n\tfor ;\n\tMon, 23 Mar 2020 17:53:06 +0100 (CET)","from pendragon.ideasonboard.com (81-175-216-236.bb.dnainternet.fi\n\t[81.175.216.236])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id EFDEF308;\n\tMon, 23 Mar 2020 17:53:05 +0100 (CET)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1584982386;\n\tbh=rj4CVKno+zhoE18qlBqN1T3VlYv+TYOK17eW30mF8Jc=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=m8uMVzTbhpxgwCdIWvpiiszHNZwXdIbMxsvaPDf1PKHqo+LZLAiqzZnQ2TdZfKpsm\n\tW/g7j2nuNMNs5ij8inGQlh/l8zKnYaEPFMC9N3sdOkUpFux5KcwM1GAk9/AGJN6ZJO\n\tW7Kbqm7aI9JCjRL64nYWpG1Zds8x5OtoU7R3yjbA=","Date":"Mon, 23 Mar 2020 18:52:56 +0200","From":"Laurent Pinchart ","To":"Kieran Bingham ","Cc":"libcamera-devel@lists.libcamera.org","Message-ID":"<20200323165256.GQ4768@pendragon.ideasonboard.com>","References":"<20200323142205.28342-1-laurent.pinchart@ideasonboard.com>\n\t<20200323142205.28342-6-laurent.pinchart@ideasonboard.com>\n\t<30e79ff1-8f87-9ec7-b88b-0eb6c92943ed@ideasonboard.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","In-Reply-To":"<30e79ff1-8f87-9ec7-b88b-0eb6c92943ed@ideasonboard.com>","User-Agent":"Mutt/1.10.1 (2018-07-13)","Subject":"Re: [libcamera-devel] [PATCH 05/21] qcam: main_window: Move capture\n\tevent processing to main thread","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","X-List-Received-Date":"Mon, 23 Mar 2020 16:53:06 -0000"}},{"id":4242,"web_url":"https://patchwork.libcamera.org/comment/4242/","msgid":"<1c601381-a307-d005-712b-bd53259a6284@ideasonboard.com>","date":"2020-03-23T17:31:31","subject":"Re: [libcamera-devel] [PATCH 05/21] qcam: main_window: Move capture\n\tevent processing to main thread","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Hi Laurent,\n\nOn 23/03/2020 16:52, Laurent Pinchart wrote:\n> Hi Kieran,\n> \n> On Mon, Mar 23, 2020 at 02:59:08PM +0000, Kieran Bingham wrote:\n>> On 23/03/2020 14:21, Laurent Pinchart wrote:\n>>> To avoid blocking the camera manager for a long amount of time, move\n>>> capture event processing to the main thread. Captured buffers are added\n>>> to a queue and an event is posted to the main window to signal\n>>> availability of a buffer.\n>>\n>> Is the 'queue' necessary?\n>> Could the buffers not be passed through the event?\n> \n> I would then have no way in processCapture() to ignore the event after\n> stopping the camera. I could check isCapturing_, but at least in theory,\n> we could stop and restart and have the pending event generated before\n> stopped delivered after the restart. I think a queue is cleaner as it\n> gives us full control.\n> \n\nOk, with minors resolved,\n\nReviewed-by: Kieran Bingham \n\n>>> Signed-off-by: Laurent Pinchart \n>>> ---\n>>> src/qcam/main_window.cpp | 54 +++++++++++++++++++++++++++++++++++++++-\n>>> src/qcam/main_window.h | 8 ++++++\n>>> 2 files changed, 61 insertions(+), 1 deletion(-)\n>>>\n>>> diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp\n>>> index 354a53367d0f..afd8b9c413f5 100644\n>>> --- a/src/qcam/main_window.cpp\n>>> +++ b/src/qcam/main_window.cpp\n>>> @@ -19,6 +19,7 @@\n>>> #include \n>>> #include \n>>> #include \n>>> +#include \n>>> #include \n>>> #include \n>>> #include \n>>> @@ -31,6 +32,21 @@\n>>> \n>>> using namespace libcamera;\n>>> \n>>> +class CaptureEvent : public QEvent\n>>> +{\n>>> +public:\n>>> +\tCaptureEvent()\n>>> +\t\t: QEvent(type())\n>>> +\t{\n>>> +\t}\n>>> +\n>>> +\tstatic Type type()\n>>> +\t{\n>>> +\t\tstatic int type = QEvent::registerEventType();\n>>> +\t\treturn static_cast(type);\n>>> +\t}\n>>> +};\n>>> +\n>>> MainWindow::MainWindow(CameraManager *cm, const OptionsParser::Options &options)\n>>> \t: options_(options), cm_(cm), allocator_(nullptr), isCapturing_(false)\n>>> {\n>>> @@ -63,6 +79,16 @@ MainWindow::~MainWindow()\n>>> \t}\n>>> }\n>>> \n>>> +bool MainWindow::event(QEvent *e)\n>>> +{\n>>> +\tif (e->type() == CaptureEvent::type()) {\n>>> +\t\tprocessCapture();\n>>> +\t\treturn true;\n>>> +\t}\n>>> +\n>>> +\treturn QMainWindow::event(e);\n>>> +}\n>>> +\n>>> int MainWindow::createToolbars()\n>>> {\n>>> \tQAction *action;\n>>> @@ -343,6 +369,13 @@ void MainWindow::stopCapture()\n>>> \n>>> \tconfig_.reset();\n>>> \n>>> +\t/*\n>>> +\t * A CaptureEvent may have been posted before we stopped the camera,\n>>> +\t * but not processed yet. Clear the queue of done buffers to avoid\n>>> +\t * racing with the event handler.\n>>> +\t */\n>>> +\tdoneQueue_.clear();\n>>> +\n>>\n>> Do we not need to lock mutex_ here?\n> \n> No, because at this point there can't be any call to\n> MainWindow::requestComplete(), as the camera is stopped. This function,\n> as well as MainWindow::processCapture(), run in the same thread, so they\n> can't run concurrently.\n> \n>>> \ttitleTimer_.stop();\n>>> \tsetWindowTitle(title_);\n>>> }\n>>> @@ -371,10 +404,29 @@ void MainWindow::requestComplete(Request *request)\n>>> \t\treturn;\n>>> \n>>> \tconst std::map &buffers = request->buffers();\n>>> +\tFrameBuffer *buffer = buffers.begin()->second;\n>>> +\n>>> +\t{\n>>> +\t\tQMutexLocker locker(&mutex_);\n>>> +\t\tdoneQueue_.enqueue(buffer);\n>>> +\t}\n>>> +\n>>> +\tQCoreApplication::postEvent(this, new CaptureEvent);\n>>> +}\n>>> +\n>>> +void MainWindow::processCapture()\n>>> +{\n>>> +\tFrameBuffer *buffer;\n>>\n>> This scoping is to ensure the locker unlocks after the dequeue right?\n> \n> Correct.\n> \n>> Perhaps a new line between the FrameBuffer declaration and the start of\n>> the scope? It looks a bit like some sort of badly defined inline\n>> function otherwise :-S\n> \n> OK.\n> \n>>> +\t{\n>>> +\t\tQMutexLocker locker(&mutex_);\n>>> +\t\tif (doneQueue_.isEmpty())\n>>> +\t\t\treturn;\n>>> +\n>>> +\t\tbuffer = doneQueue_.dequeue();\n>>> +\t}\n>>> \n>>> \tframesCaptured_++;\n>>> \n>>> -\tFrameBuffer *buffer = buffers.begin()->second;\n>>> \tconst FrameMetadata &metadata = buffer->metadata();\n>>> \n>>> \tdouble fps = metadata.timestamp - lastBufferTime_;\n>>> diff --git a/src/qcam/main_window.h b/src/qcam/main_window.h\n>>> index 720a3393e3dc..c623120d5894 100644\n>>> --- a/src/qcam/main_window.h\n>>> +++ b/src/qcam/main_window.h\n>>> @@ -11,7 +11,9 @@\n>>> \n>>> #include \n>>> #include \n>>> +#include \n>>> #include \n>>> +#include \n>>> #include \n>>> \n>>> #include \n>>> @@ -40,6 +42,8 @@ public:\n>>> \tMainWindow(CameraManager *cm, const OptionsParser::Options &options);\n>>> \t~MainWindow();\n>>> \n>>> +\tbool event(QEvent *e) override;\n>>> +\n>>> private Q_SLOTS:\n>>> \tvoid quit();\n>>> \tvoid updateTitle();\n>>> @@ -57,6 +61,7 @@ private:\n>>> \tint openCamera();\n>>> \n>>> \tvoid requestComplete(Request *request);\n>>> +\tvoid processCapture();\n>>> \tint display(FrameBuffer *buffer);\n>>> \tvoid queueRequest(FrameBuffer *buffer);\n>>> \n>>> @@ -78,6 +83,9 @@ private:\n>>> \tuint32_t previousFrames_;\n>>> \tuint32_t framesCaptured_;\n>>> \n>>> +\tQMutex mutex_;\n>>> +\tQQueue doneQueue_;\n>>> +\n>>> \tQToolBar *toolbar_;\n>>> \tViewFinder *viewfinder_;\n>>> \tstd::map> mappedBuffers_;\n>","headers":{"Return-Path":"","Received":["from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 9CC3360417\n\tfor ;\n\tMon, 23 Mar 2020 18:31:34 +0100 (CET)","from [192.168.0.20]\n\t(cpc89242-aztw30-2-0-cust488.18-1.cable.virginm.net [86.31.129.233])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 34C60308;\n\tMon, 23 Mar 2020 18:31:34 +0100 (CET)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1584984694;\n\tbh=1mLQsU/5L32xbJMlMAX6E6d02vAVQa2FO2r/uChIpSk=;\n\th=Reply-To:Subject:To:Cc:References:From:Date:In-Reply-To:From;\n\tb=SPlzlCJVGk48yNG0fKp5vOsUYkkjA/HEo6hXCb/7ApLniQd7V7FLyyxwEY6PyYngM\n\teh84rTHOaa4N+Xvk8YcJtTSU+E++NeX5/KMzpSiWgyVTLJTbjXhg6ugOgB/R7ytITT\n\tzLlxBK/T/Ii1CNqS6pqaRSXyqB2/bshtl2B2LqxI=","Reply-To":"kieran.bingham@ideasonboard.com","To":"Laurent Pinchart ","Cc":"libcamera-devel@lists.libcamera.org","References":"<20200323142205.28342-1-laurent.pinchart@ideasonboard.com>\n\t<20200323142205.28342-6-laurent.pinchart@ideasonboard.com>\n\t<30e79ff1-8f87-9ec7-b88b-0eb6c92943ed@ideasonboard.com>\n\t<20200323165256.GQ4768@pendragon.ideasonboard.com>","From":"Kieran Bingham ","Openpgp":"preference=signencrypt","Autocrypt":"addr=kieran.bingham@ideasonboard.com; keydata=\n\tmQINBFYE/WYBEACs1PwjMD9rgCu1hlIiUA1AXR4rv2v+BCLUq//vrX5S5bjzxKAryRf0uHat\n\tV/zwz6hiDrZuHUACDB7X8OaQcwhLaVlq6byfoBr25+hbZG7G3+5EUl9cQ7dQEdvNj6V6y/SC\n\trRanWfelwQThCHckbobWiQJfK9n7rYNcPMq9B8e9F020LFH7Kj6YmO95ewJGgLm+idg1Kb3C\n\tpotzWkXc1xmPzcQ1fvQMOfMwdS+4SNw4rY9f07Xb2K99rjMwZVDgESKIzhsDB5GY465sCsiQ\n\tcSAZRxqE49RTBq2+EQsbrQpIc8XiffAB8qexh5/QPzCmR4kJgCGeHIXBtgRj+nIkCJPZvZtf\n\tKr2EAbc6tgg6DkAEHJb+1okosV09+0+TXywYvtEop/WUOWQ+zo+Y/OBd+8Ptgt1pDRyOBzL8\n\tRXa8ZqRf0Mwg75D+dKntZeJHzPRJyrlfQokngAAs4PaFt6UfS+ypMAF37T6CeDArQC41V3ko\n\tlPn1yMsVD0p+6i3DPvA/GPIksDC4owjnzVX9kM8Zc5Cx+XoAN0w5Eqo4t6qEVbuettxx55gq\n\t8K8FieAjgjMSxngo/HST8TpFeqI5nVeq0/lqtBRQKumuIqDg+Bkr4L1V/PSB6XgQcOdhtd36\n\tOe9X9dXB8YSNt7VjOcO7BTmFn/Z8r92mSAfHXpb07YJWJosQOQARAQABtDBLaWVyYW4gQmlu\n\tZ2hhbSA8a2llcmFuLmJpbmdoYW1AaWRlYXNvbmJvYXJkLmNvbT6JAlcEEwEKAEECGwMFCwkI\n\tBwIGFQgJCgsCBBYCAwECHgECF4ACGQEWIQSQLdeYP70o/eNy1HqhHkZyEKRh/QUCXWTtygUJ\n\tCyJXZAAKCRChHkZyEKRh/f8dEACTDsbLN2nioNZMwyLuQRUAFcXNolDX48xcUXsWS2QjxaPm\n\tVsJx8Uy8aYkS85mdPBh0C83OovQR/OVbr8AxhGvYqBs3nQvbWuTl/+4od7DfK2VZOoKBAu5S\n\tQK2FYuUcikDqYcFWJ8DQnubxfE8dvzojHEkXw0sA4igINHDDFX3HJGZtLio+WpEFQtCbfTAG\n\tYZslasz1YZRbwEdSsmO3/kqy5eMnczlm8a21A3fKUo3g8oAZEFM+f4DUNzqIltg31OAB/kZS\n\tenKZQ/SWC8PmLg/ZXBrReYakxXtkP6w3FwMlzOlhGxqhIRNiAJfXJBaRhuUWzPOpEDE9q5YJ\n\tBmqQL2WJm1VSNNVxbXJHpaWMH1sA2R00vmvRrPXGwyIO0IPYeUYQa3gsy6k+En/aMQJd27dp\n\taScf9am9PFICPY5T4ppneeJLif2lyLojo0mcHOV+uyrds9XkLpp14GfTkeKPdPMrLLTsHRfH\n\tfA4I4OBpRrEPiGIZB/0im98MkGY/Mu6qxeZmYLCcgD6qz4idOvfgVOrNh+aA8HzIVR+RMW8H\n\tQGBN9f0E3kfwxuhl3omo6V7lDw8XOdmuWZNC9zPq1UfryVHANYbLGz9KJ4Aw6M+OgBC2JpkD\n\thXMdHUkC+d20dwXrwHTlrJi1YNp6rBc+xald3wsUPOZ5z8moTHUX/uPA/qhGsbkCDQRWBP1m\n\tARAAzijkb+Sau4hAncr1JjOY+KyFEdUNxRy+hqTJdJfaYihxyaj0Ee0P0zEi35CbE6lgU0Uz\n\ttih9fiUbSV3wfsWqg1Ut3/5rTKu7kLFp15kF7eqvV4uezXRD3Qu4yjv/rMmEJbbD4cTvGCYI\n\td6MDC417f7vK3hCbCVIZSp3GXxyC1LU+UQr3fFcOyCwmP9vDUR9JV0BSqHHxRDdpUXE26Dk6\n\tmhf0V1YkspE5St814ETXpEus2urZE5yJIUROlWPIL+hm3NEWfAP06vsQUyLvr/GtbOT79vXl\n\tEn1aulcYyu20dRRxhkQ6iILaURcxIAVJJKPi8dsoMnS8pB0QW12AHWuirPF0g6DiuUfPmrA5\n\tPKe56IGlpkjc8cO51lIxHkWTpCMWigRdPDexKX+Sb+W9QWK/0JjIc4t3KBaiG8O4yRX8ml2R\n\t+rxfAVKM6V769P/hWoRGdgUMgYHFpHGSgEt80OKK5HeUPy2cngDUXzwrqiM5Sz6Od0qw5pCk\n\tNlXqI0W/who0iSVM+8+RmyY0OEkxEcci7rRLsGnM15B5PjLJjh1f2ULYkv8s4SnDwMZ/kE04\n\t/UqCMK/KnX8pwXEMCjz0h6qWNpGwJ0/tYIgQJZh6bqkvBrDogAvuhf60Sogw+mH8b+PBlx1L\n\toeTK396wc+4c3BfiC6pNtUS5GpsPMMjYMk7kVvEAEQEAAYkCPAQYAQoAJgIbDBYhBJAt15g/\n\tvSj943LUeqEeRnIQpGH9BQJdizzIBQkLSKZiAAoJEKEeRnIQpGH9eYgQAJpjaWNgqNOnMTmD\n\tMJggbwjIotypzIXfhHNCeTkG7+qCDlSaBPclcPGYrTwCt0YWPU2TgGgJrVhYT20ierN8LUvj\n\t6qOPTd+Uk7NFzL65qkh80ZKNBFddx1AabQpSVQKbdcLb8OFs85kuSvFdgqZwgxA1vl4TFhNz\n\tPZ79NAmXLackAx3sOVFhk4WQaKRshCB7cSl+RIng5S/ThOBlwNlcKG7j7W2MC06BlTbdEkUp\n\tECzuuRBv8wX4OQl+hbWbB/VKIx5HKlLu1eypen/5lNVzSqMMIYkkZcjV2SWQyUGxSwq0O/sx\n\tS0A8/atCHUXOboUsn54qdxrVDaK+6jIAuo8JiRWctP16KjzUM7MO0/+4zllM8EY57rXrj48j\n\tsbEYX0YQnzaj+jO6kJtoZsIaYR7rMMq9aUAjyiaEZpmP1qF/2sYenDx0Fg2BSlLvLvXM0vU8\n\tpQk3kgDu7kb/7PRYrZvBsr21EIQoIjXbZxDz/o7z95frkP71EaICttZ6k9q5oxxA5WC6sTXc\n\tMW8zs8avFNuA9VpXt0YupJd2ijtZy2mpZNG02fFVXhIn4G807G7+9mhuC4XG5rKlBBUXTvPU\n\tAfYnB4JBDLmLzBFavQfvonSfbitgXwCG3vS+9HEwAjU30Bar1PEOmIbiAoMzuKeRm2LVpmq4\n\tWZw01QYHU/GUV/zHJSFk","Organization":"Ideas on Board","Message-ID":"<1c601381-a307-d005-712b-bd53259a6284@ideasonboard.com>","Date":"Mon, 23 Mar 2020 17:31:31 +0000","User-Agent":"Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101\n\tThunderbird/60.9.1","MIME-Version":"1.0","In-Reply-To":"<20200323165256.GQ4768@pendragon.ideasonboard.com>","Content-Type":"text/plain; charset=utf-8","Content-Language":"en-GB","Content-Transfer-Encoding":"7bit","Subject":"Re: [libcamera-devel] [PATCH 05/21] qcam: main_window: Move capture\n\tevent processing to main thread","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","X-List-Received-Date":"Mon, 23 Mar 2020 17:31:34 -0000"}}]