[{"id":16858,"web_url":"https://patchwork.libcamera.org/comment/16858/","msgid":"","date":"2021-05-10T12:54:21","subject":"Re: [libcamera-devel] [PATCH v6 3/6] ipa: raspberrypi: Switch to\n\tstd::scoped_lock in the Metadata class","submitter":{"id":42,"url":"https://patchwork.libcamera.org/api/people/42/","name":"David Plowman","email":"david.plowman@raspberrypi.com"},"content":"HI Naush\n\nThanks for this patch. I must confess I haven't encountered this\n\"scoped_lock\" before, but it seems to be just the ticket.\n\nOn Mon, 10 May 2021 at 10:59, Naushir Patuck wrote:\n>\n> Replace std::lock_guard with std::scoped_lock. When locking a single\n> mutex, both are functionally the same. When locking two mutexes in the\n> operator= overload, the scoped_lock uses a deadlock avoidance algorithm\n> to avoid deadlock.\n>\n> Signed-off-by: Naushir Patuck \n\nReviewed-by: David Plowman \n\nThanks!\nDavid\n\n> ---\n> src/ipa/raspberrypi/controller/metadata.hpp | 9 ++++-----\n> 1 file changed, 4 insertions(+), 5 deletions(-)\n>\n> diff --git a/src/ipa/raspberrypi/controller/metadata.hpp b/src/ipa/raspberrypi/controller/metadata.hpp\n> index 07dd28ed9e0a..e735cfbe0480 100644\n> --- a/src/ipa/raspberrypi/controller/metadata.hpp\n> +++ b/src/ipa/raspberrypi/controller/metadata.hpp\n> @@ -22,14 +22,14 @@ public:\n> template\n> void Set(std::string const &tag, T const &value)\n> {\n> - std::lock_guard lock(mutex_);\n> + std::scoped_lock lock(mutex_);\n> data_[tag] = value;\n> }\n>\n> template\n> int Get(std::string const &tag, T &value) const\n> {\n> - std::lock_guard lock(mutex_);\n> + std::scoped_lock lock(mutex_);\n> auto it = data_.find(tag);\n> if (it == data_.end())\n> return -1;\n> @@ -39,14 +39,13 @@ public:\n>\n> void Clear()\n> {\n> - std::lock_guard lock(mutex_);\n> + std::scoped_lock lock(mutex_);\n> data_.clear();\n> }\n>\n> Metadata &operator=(Metadata const &other)\n> {\n> - std::lock_guard lock(mutex_);\n> - std::lock_guard other_lock(other.mutex_);\n> + std::scoped_lock lock(mutex_, other.mutex_);\n> data_ = other.data_;\n> return *this;\n> }\n> --\n> 2.25.1\n>\n> _______________________________________________\n> libcamera-devel mailing list\n> libcamera-devel@lists.libcamera.org\n> https://lists.libcamera.org/listinfo/libcamera-devel","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 A66F5BF829\n\tfor ;\n\tMon, 10 May 2021 12:54:35 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 1E5B7688E5;\n\tMon, 10 May 2021 14:54:35 +0200 (CEST)","from mail-wr1-x429.google.com (mail-wr1-x429.google.com\n\t[IPv6:2a00:1450:4864:20::429])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 19710602BE\n\tfor ;\n\tMon, 10 May 2021 14:54:33 +0200 (CEST)","by mail-wr1-x429.google.com with SMTP id n2so16573003wrm.0\n\tfor ;\n\tMon, 10 May 2021 05:54:33 -0700 (PDT)"],"Authentication-Results":"lancelot.ideasonboard.com;\n\tdkim=fail reason=\"signature verification failed\" (2048-bit key;\n\tunprotected) header.d=raspberrypi.com header.i=@raspberrypi.com\n\theader.b=\"BH2hcfD4\"; 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\n\tMon, 10 May 2021 05:54:32 -0700 (PDT)","MIME-Version":"1.0","References":"<20210510095814.3732400-1-naush@raspberrypi.com>\n\t<20210510095814.3732400-4-naush@raspberrypi.com>","In-Reply-To":"<20210510095814.3732400-4-naush@raspberrypi.com>","From":"David Plowman ","Date":"Mon, 10 May 2021 13:54:21 +0100","Message-ID":"","To":"Naushir Patuck ","Subject":"Re: [libcamera-devel] [PATCH v6 3/6] ipa: raspberrypi: Switch to\n\tstd::scoped_lock in the Metadata class","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","Cc":"libcamera devel ","Content-Type":"text/plain; charset=\"us-ascii\"","Content-Transfer-Encoding":"7bit","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}},{"id":16874,"web_url":"https://patchwork.libcamera.org/comment/16874/","msgid":"","date":"2021-05-10T23:48:22","subject":"Re: [libcamera-devel] [PATCH v6 3/6] ipa: raspberrypi: Switch to\n\tstd::scoped_lock in the Metadata class","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"content":"Hi Naush,\n\nThank you for the patch.\n\nOn Mon, May 10, 2021 at 10:58:12AM +0100, Naushir Patuck wrote:\n> Replace std::lock_guard with std::scoped_lock. When locking a single\n> mutex, both are functionally the same. When locking two mutexes in the\n> operator= overload, the scoped_lock uses a deadlock avoidance algorithm\n> to avoid deadlock.\n> \n> Signed-off-by: Naushir Patuck \n\nReviewed-by: Laurent Pinchart \n\n> ---\n> src/ipa/raspberrypi/controller/metadata.hpp | 9 ++++-----\n> 1 file changed, 4 insertions(+), 5 deletions(-)\n> \n> diff --git a/src/ipa/raspberrypi/controller/metadata.hpp b/src/ipa/raspberrypi/controller/metadata.hpp\n> index 07dd28ed9e0a..e735cfbe0480 100644\n> --- a/src/ipa/raspberrypi/controller/metadata.hpp\n> +++ b/src/ipa/raspberrypi/controller/metadata.hpp\n> @@ -22,14 +22,14 @@ public:\n> \ttemplate\n> \tvoid Set(std::string const &tag, T const &value)\n> \t{\n> -\t\tstd::lock_guard lock(mutex_);\n> +\t\tstd::scoped_lock lock(mutex_);\n> \t\tdata_[tag] = value;\n> \t}\n> \n> \ttemplate\n> \tint Get(std::string const &tag, T &value) const\n> \t{\n> -\t\tstd::lock_guard lock(mutex_);\n> +\t\tstd::scoped_lock lock(mutex_);\n> \t\tauto it = data_.find(tag);\n> \t\tif (it == data_.end())\n> \t\t\treturn -1;\n> @@ -39,14 +39,13 @@ public:\n> \n> \tvoid Clear()\n> \t{\n> -\t\tstd::lock_guard lock(mutex_);\n> +\t\tstd::scoped_lock lock(mutex_);\n> \t\tdata_.clear();\n> \t}\n> \n> \tMetadata &operator=(Metadata const &other)\n> \t{\n> -\t\tstd::lock_guard lock(mutex_);\n> -\t\tstd::lock_guard other_lock(other.mutex_);\n> +\t\tstd::scoped_lock lock(mutex_, other.mutex_);\n> \t\tdata_ = other.data_;\n> \t\treturn *this;\n> \t}","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 7B199BF839\n\tfor ;\n\tMon, 10 May 2021 23:48:31 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id E9DB668911;\n\tTue, 11 May 2021 01:48:30 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 87055602B8\n\tfor ;\n\tTue, 11 May 2021 01:48:29 +0200 (CEST)","from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi\n\t[62.78.145.57])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id E0DFA6EF;\n\tTue, 11 May 2021 01:48:28 +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=\"BAT+AKMD\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1620690509;\n\tbh=IESpY9c+m3FP7Xn1YsESLCHzBqgOb1juu0dhAZbnFTg=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=BAT+AKMDsSi6rexHOq1vFu6BIgySqpxjLcdu/o1/Tjy78g5dRnHkyOlY+I/qirANc\n\tlj858BMFJh6XWhjQ5HSVjO76f8QKSOTR7s28uLaIG4uxS/nc1GgO121vwRa1Ps/evl\n\tsWKro7AO8k7VafID4QEyS+qZUoyBG+6y3rcV90pY=","Date":"Tue, 11 May 2021 02:48:22 +0300","From":"Laurent Pinchart ","To":"Naushir Patuck ","Message-ID":"","References":"<20210510095814.3732400-1-naush@raspberrypi.com>\n\t<20210510095814.3732400-4-naush@raspberrypi.com>","MIME-Version":"1.0","Content-Disposition":"inline","In-Reply-To":"<20210510095814.3732400-4-naush@raspberrypi.com>","Subject":"Re: [libcamera-devel] [PATCH v6 3/6] ipa: raspberrypi: Switch to\n\tstd::scoped_lock in the Metadata class","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","Cc":"libcamera-devel@lists.libcamera.org","Content-Type":"text/plain; charset=\"us-ascii\"","Content-Transfer-Encoding":"7bit","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}}]