{"id":15260,"url":"https://patchwork.libcamera.org/api/1.1/patches/15260/?format=json","web_url":"https://patchwork.libcamera.org/patch/15260/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/1.1/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":"<20220107125506.1477795-3-kieran.bingham@ideasonboard.com>","date":"2022-01-07T12:55:06","name":"[libcamera-devel,2/2] libcamera: base: signal: Prevent excessive slot usage","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"a70b89e65ceed980027e49398eaf9f9001f4873f","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/1.1/people/4/?format=json","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"delegate":{"id":11,"url":"https://patchwork.libcamera.org/api/1.1/users/11/?format=json","username":"kbingham","first_name":"Kieran","last_name":"Bingham","email":"kieran.bingham@ideasonboard.com"},"mbox":"https://patchwork.libcamera.org/patch/15260/mbox/","series":[{"id":2882,"url":"https://patchwork.libcamera.org/api/1.1/series/2882/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=2882","date":"2022-01-07T12:55:04","name":"libcamera: pipeline_handler: Prepare requests","version":1,"mbox":"https://patchwork.libcamera.org/series/2882/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/15260/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/15260/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 BFF20C325A\n\tfor ;\n\tFri, 7 Jan 2022 12:55:14 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 483BC608E6;\n\tFri, 7 Jan 2022 13:55:13 +0100 (CET)","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 16F926091E\n\tfor ;\n\tFri, 7 Jan 2022 13:55:11 +0100 (CET)","from Monstersaurus.ksquared.org.uk.beta.tailscale.net\n\t(cpc89244-aztw30-2-0-cust3082.18-1.cable.virginm.net [86.31.172.11])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id B56FD11BB;\n\tFri, 7 Jan 2022 13:55:10 +0100 (CET)"],"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=\"J/p3E8y6\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1641560110;\n\tbh=i20JeXHm30wC0P+xND/ZuoxhTyzcltGmvvWoMiRwLxM=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=J/p3E8y6Pk7yfOlYdvKjyzNI33SimLOOO8MqSRmallVNcVHdDs7wauRO73aOk8c9m\n\tm1LPggT/9pOZ4VnrRCCLOut5+bfFhmCGNW9rM84XTtGlgG5r+JQU/5oTA2brc3E8NO\n\tjGjGUOrnW3eDg8sD1QgghDcdf30Wne+QgZiVTy6g=","From":"Kieran Bingham ","To":"libcamera devel ","Date":"Fri, 7 Jan 2022 12:55:06 +0000","Message-Id":"<20220107125506.1477795-3-kieran.bingham@ideasonboard.com>","X-Mailer":"git-send-email 2.32.0","In-Reply-To":"<20220107125506.1477795-1-kieran.bingham@ideasonboard.com>","References":"<20220107125506.1477795-1-kieran.bingham@ideasonboard.com>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","Subject":"[libcamera-devel] [PATCH 2/2] libcamera: base: signal: Prevent\n\texcessive slot usage","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","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"Slots are not expected to be connected to lots of signals. Our normal\nuse case is a one to one mapping with a signal expected to call one\nslot.\n\nWhile we support multiple slots, excessive use is likely the result of a\nbug indicating a failure to disconnect slots or repeated connection of a\nslot which can lead to memory leaks and poor performance when deleting\nthe Object.\n\nAssert that a maximum of 8 slots are connected which will catch any bug\nand still allow some multiple slot usage. If this limit is ever met it\ncan be extended and considered at that time.\n\nSigned-off-by: Kieran Bingham \n---\n\nNote that this patch causes the CTS tests to fail as they hit this\nassertion.\n\nIt is not yet investigated if we really need more slots or if the\nassertion has already caught a slot-leak, but posting for early review\nanyway.\n\n src/libcamera/base/signal.cpp | 8 ++++++++\n 1 file changed, 8 insertions(+)","diff":"diff --git a/src/libcamera/base/signal.cpp b/src/libcamera/base/signal.cpp\nindex 9df45d079a42..7e6a23cc909d 100644\n--- a/src/libcamera/base/signal.cpp\n+++ b/src/libcamera/base/signal.cpp\n@@ -7,6 +7,7 @@\n \n #include \n \n+#include \n #include \n \n /**\n@@ -35,6 +36,13 @@ void SignalBase::connect(BoundMethodBase *slot)\n \tif (object)\n \t\tobject->connect(this);\n \tslots_.push_back(slot);\n+\n+\t/*\n+\t * Slots are not expected to be used to connect many items. If we exceed\n+\t * a reasonable amount, presume that there is a bug and fail fast on\n+\t * debug builds.\n+\t */\n+\tASSERT(slots_.size() < 8);\n }\n \n void SignalBase::disconnect(Object *object)\n","prefixes":["libcamera-devel","2/2"]}