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GET /api/1.1/patches/2699/?format=api
{ "id": 2699, "url": "https://patchwork.libcamera.org/api/1.1/patches/2699/?format=api", "web_url": "https://patchwork.libcamera.org/patch/2699/", "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": "<20200120002437.6633-13-laurent.pinchart@ideasonboard.com>", "date": "2020-01-20T00:24:30", "name": "[libcamera-devel,12/19] libcamera: signal: Make connection and disconnection thread-safe", "commit_ref": null, "pull_url": null, "state": "superseded", "archived": false, "hash": "401b92151879ac0724a85fb53c847df4f6ad833e", "submitter": { "id": 2, "url": "https://patchwork.libcamera.org/api/1.1/people/2/?format=api", "name": "Laurent Pinchart", "email": "laurent.pinchart@ideasonboard.com" }, "delegate": null, "mbox": "https://patchwork.libcamera.org/patch/2699/mbox/", "series": [ { "id": 641, "url": "https://patchwork.libcamera.org/api/1.1/series/641/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=641", "date": "2020-01-20T00:24:19", "name": "Initial libcamera threading model", "version": 1, "mbox": "https://patchwork.libcamera.org/series/641/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/patches/2699/comments/", "check": "pending", "checks": "https://patchwork.libcamera.org/api/patches/2699/checks/", "tags": {}, "headers": { "Return-Path": "<laurent.pinchart@ideasonboard.com>", "Received": [ "from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id E66CE607C4\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tMon, 20 Jan 2020 01:24:46 +0100 (CET)", "from pendragon.bb.dnainternet.fi (81-175-216-236.bb.dnainternet.fi\n\t[81.175.216.236])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 8AF34504\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tMon, 20 Jan 2020 01:24:46 +0100 (CET)" ], "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1579479886;\n\tbh=51/YLrAB8DXWNr/g/YSoeq08tZX7TNIoH3L7qTNvrCc=;\n\th=From:To:Subject:Date:In-Reply-To:References:From;\n\tb=pptF5bsc/7BBVl5QEWBemumLzV38G+XXssLMHGdSP97zArUmguqP0XYAVL0c2tk8a\n\tu4n8d0/+4K0ubNSdk+nPARoR8/ICzR5ZPMKEO7JcAg5iBscuy0ks/qkIqvtnnp8TMT\n\ty8SJ0UCFKgd8U4WyHxXK45Nwb3juoXpdKPsAT2bk=", "From": "Laurent Pinchart <laurent.pinchart@ideasonboard.com>", "To": "libcamera-devel@lists.libcamera.org", "Date": "Mon, 20 Jan 2020 02:24:30 +0200", "Message-Id": "<20200120002437.6633-13-laurent.pinchart@ideasonboard.com>", "X-Mailer": "git-send-email 2.24.1", "In-Reply-To": "<20200120002437.6633-1-laurent.pinchart@ideasonboard.com>", "References": "<20200120002437.6633-1-laurent.pinchart@ideasonboard.com>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "Subject": "[libcamera-devel] [PATCH 12/19] libcamera: signal: Make connection\n\tand disconnection thread-safe", "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>", "X-List-Received-Date": "Mon, 20 Jan 2020 00:24:47 -0000" }, "content": "Make the signal connection and disconnection thread-safe, and document\nthem as such. This is required to make objects connectable from\ndifferent threads.\n\nThe connect(), disconnect() and emit() methods are now all protected by\na global mutex, which may generate a high lock contention. This could be\nimproved with finer-grained locks or with a pool of mutexes.\n\nSigned-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>\n---\n src/libcamera/signal.cpp | 33 +++++++++++++++++++++++++++++++++\n 1 file changed, 33 insertions(+)", "diff": "diff --git a/src/libcamera/signal.cpp b/src/libcamera/signal.cpp\nindex 9bb7eca8ed6e..6eab1fa74d42 100644\n--- a/src/libcamera/signal.cpp\n+++ b/src/libcamera/signal.cpp\n@@ -7,6 +7,8 @@\n \n #include <libcamera/signal.h>\n \n+#include \"thread.h\"\n+\n /**\n * \\file signal.h\n * \\brief Signal & slot implementation\n@@ -14,8 +16,21 @@\n \n namespace libcamera {\n \n+namespace {\n+\n+/*\n+ * Mutex to protect the SignalBase::slots_ and Object::signals_ lists. If lock\n+ * contention needs to be decreased, this could be replaced with locks in\n+ * Object and SignalBase, or with a mutex pool.\n+ */\n+Mutex signalsLock;\n+\n+} /* namespace */\n+\n void SignalBase::connect(BoundMethodBase *slot)\n {\n+\tMutexLocker locker(signalsLock);\n+\n \tObject *object = slot->object();\n \tif (object)\n \t\tobject->connect(this);\n@@ -31,6 +46,8 @@ void SignalBase::disconnect(Object *object)\n \n void SignalBase::disconnect(std::function<bool(SlotList::iterator &)> match)\n {\n+\tMutexLocker locker(signalsLock);\n+\n \tfor (auto iter = slots_.begin(); iter != slots_.end(); ) {\n \t\tif (match(iter)) {\n \t\t\tObject *object = (*iter)->object();\n@@ -47,6 +64,7 @@ void SignalBase::disconnect(std::function<bool(SlotList::iterator &)> match)\n \n SignalBase::SlotList SignalBase::slots()\n {\n+\tMutexLocker locker(signalsLock);\n \treturn slots_;\n }\n \n@@ -99,23 +117,31 @@ SignalBase::SlotList SignalBase::slots()\n * disconnected from the \\a func slot of \\a object when \\a object is destroyed.\n * Otherwise the caller shall disconnect signals manually before destroying \\a\n * object.\n+ *\n+ * \\context This function is \\threadsafe.\n */\n \n /**\n * \\fn Signal::connect(R (*func)(Args...))\n * \\brief Connect the signal to a static function slot\n * \\param[in] func The slot static function\n+ *\n+ * \\context This function is \\threadsafe.\n */\n \n /**\n * \\fn Signal::disconnect()\n * \\brief Disconnect the signal from all slots\n+ *\n+ * \\context This function is \\threadsafe.\n */\n \n /**\n * \\fn Signal::disconnect(T *object)\n * \\brief Disconnect the signal from all slots of the \\a object\n * \\param[in] object The object pointer whose slots to disconnect\n+ *\n+ * \\context This function is \\threadsafe.\n */\n \n /**\n@@ -123,12 +149,16 @@ SignalBase::SlotList SignalBase::slots()\n * \\brief Disconnect the signal from the \\a object slot member function \\a func\n * \\param[in] object The object pointer whose slots to disconnect\n * \\param[in] func The slot member function to disconnect\n+ *\n+ * \\context This function is \\threadsafe.\n */\n \n /**\n * \\fn Signal::disconnect(R (*func)(Args...))\n * \\brief Disconnect the signal from the slot static function \\a func\n * \\param[in] func The slot static function to disconnect\n+ *\n+ * \\context This function is \\threadsafe.\n */\n \n /**\n@@ -141,6 +171,9 @@ SignalBase::SlotList SignalBase::slots()\n * function are passed to the slot functions unchanged. If a slot modifies one\n * of the arguments (when passed by pointer or reference), the modification is\n * thus visible to all subsequently called slots.\n+ *\n+ * This function is not \\threadsafe, but thread-safety is guaranteed against\n+ * concurrent connect() and disconnect() calls.\n */\n \n } /* namespace libcamera */\n", "prefixes": [ "libcamera-devel", "12/19" ] }