{"id":1193,"url":"https://patchwork.libcamera.org/api/1.1/patches/1193/?format=json","web_url":"https://patchwork.libcamera.org/patch/1193/","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":"<20190511091907.10050-9-niklas.soderlund@ragnatech.se>","date":"2019-05-11T09:19:04","name":"[libcamera-devel,v3,08/11] libcamera: media_device: Add functions to lock device for other processes","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"20f71d574889c6692d0f6907d68c816410daf49a","submitter":{"id":5,"url":"https://patchwork.libcamera.org/api/1.1/people/5/?format=json","name":"Niklas Söderlund","email":"niklas.soderlund@ragnatech.se"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/1193/mbox/","series":[{"id":303,"url":"https://patchwork.libcamera.org/api/1.1/series/303/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=303","date":"2019-05-11T09:18:56","name":"libcamerea: Add support for exclusive access to cameras between processes","version":3,"mbox":"https://patchwork.libcamera.org/series/303/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/1193/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/1193/checks/","tags":{},"headers":{"Return-Path":"","Received":["from bin-mail-out-05.binero.net (bin-mail-out-05.binero.net\n\t[195.74.38.228])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 18EDF60E7A\n\tfor ;\n\tSat, 11 May 2019 11:19:57 +0200 (CEST)","from localhost.localdomain (unknown [185.224.57.161])\n\tby bin-vsp-out-02.atm.binero.net (Halon) with ESMTPA\n\tid f0bd0a02-73cd-11e9-8e2f-005056917f90;\n\tSat, 11 May 2019 11:19:56 +0200 (CEST)"],"X-Halon-ID":"f0bd0a02-73cd-11e9-8e2f-005056917f90","Authorized-sender":"niklas@soderlund.pp.se","From":"=?utf-8?q?Niklas_S=C3=B6derlund?= ","To":"libcamera-devel@lists.libcamera.org","Date":"Sat, 11 May 2019 11:19:04 +0200","Message-Id":"<20190511091907.10050-9-niklas.soderlund@ragnatech.se>","X-Mailer":"git-send-email 2.21.0","In-Reply-To":"<20190511091907.10050-1-niklas.soderlund@ragnatech.se>","References":"<20190511091907.10050-1-niklas.soderlund@ragnatech.se>","MIME-Version":"1.0","Content-Type":"text/plain; charset=UTF-8","Content-Transfer-Encoding":"8bit","Subject":"[libcamera-devel] [PATCH v3 08/11] libcamera: media_device: Add\n\tfunctions to lock device for other processes","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.23","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","X-List-Received-Date":"Sat, 11 May 2019 09:19:57 -0000"},"content":"Add lock() and unlock() which are backed by lockf() and allows an\ninstance of libcamera to claim exclusive access to a media device.\nThese functions are the base of allowing multiple user of libcamera to\ncoexist in the system without stepping on each others toes.\n\nSigned-off-by: Niklas Söderlund \n---\n src/libcamera/include/media_device.h | 4 ++\n src/libcamera/media_device.cpp | 58 +++++++++++++++++++++++++++-\n 2 files changed, 61 insertions(+), 1 deletion(-)","diff":"diff --git a/src/libcamera/include/media_device.h b/src/libcamera/include/media_device.h\nindex e513a2fee1b91a1b..7b88e2875d59dfc3 100644\n--- a/src/libcamera/include/media_device.h\n+++ b/src/libcamera/include/media_device.h\n@@ -30,6 +30,9 @@ public:\n \tvoid release();\n \tbool busy() const { return acquired_; }\n \n+\tbool lock();\n+\tvoid unlock();\n+\n \tint populate();\n \tbool valid() const { return valid_; }\n \n@@ -58,6 +61,7 @@ private:\n \tint fd_;\n \tbool valid_;\n \tbool acquired_;\n+\tbool lockOwner_;\n \n \tint open();\n \tvoid close();\ndiff --git a/src/libcamera/media_device.cpp b/src/libcamera/media_device.cpp\nindex 62c59e7e8fc0299f..874ecc06e4bd9c94 100644\n--- a/src/libcamera/media_device.cpp\n+++ b/src/libcamera/media_device.cpp\n@@ -63,7 +63,8 @@ LOG_DEFINE_CATEGORY(MediaDevice)\n * populate() before the media graph can be queried.\n */\n MediaDevice::MediaDevice(const std::string &deviceNode)\n-\t: deviceNode_(deviceNode), fd_(-1), valid_(false), acquired_(false)\n+\t: deviceNode_(deviceNode), fd_(-1), valid_(false), acquired_(false),\n+\t lockOwner_(false)\n {\n }\n \n@@ -118,6 +119,61 @@ void MediaDevice::release()\n \tacquired_ = false;\n }\n \n+/**\n+ * \\brief Lock the device for use by other instances of libcamera\n+ *\n+ * Multiple instances of libcamera might be running on the same system, at the\n+ * same time. To allow the different instances to coexist, system resources in\n+ * the form of media devices must be accessible for enumerating the cameras\n+ * they provide at all times, while still allowing an instance to lock a\n+ * resource while it prepares to actively use a camera from the resource.\n+ *\n+ * This method shall not be called from a pipeline handler implementation\n+ * directly, as the base PipelineHandler implementation handles this on the\n+ * behalf of the specified implementation.\n+ *\n+ * \\return True if the device could be locked, false otherwise\n+ * \\sa unlock()\n+ */\n+bool MediaDevice::lock()\n+{\n+\tif (fd_ == -1)\n+\t\treturn false;\n+\n+\t/* Do not allow nested locking in the same libcamera instance. */\n+\tif (lockOwner_)\n+\t\treturn false;\n+\n+\tif (lockf(fd_, F_TLOCK, 0))\n+\t\treturn false;\n+\n+\tlockOwner_ = true;\n+\n+\treturn true;\n+}\n+\n+/**\n+ * \\brief Unlock the device and free it for use for libcamera instances\n+ *\n+ * This method shall not be called from a pipeline handler implementation\n+ * directly, as the base PipelineHandler implementation handles this on the\n+ * behalf of the specified implementation.\n+ *\n+ * \\sa lock()\n+ */\n+void MediaDevice::unlock()\n+{\n+\tif (fd_ == -1)\n+\t\treturn;\n+\n+\tif (!lockOwner_)\n+\t\treturn;\n+\n+\tlockOwner_ = false;\n+\n+\tlockf(fd_, F_ULOCK, 0);\n+}\n+\n /**\n * \\fn MediaDevice::busy()\n * \\brief Check if a device is in use\n","prefixes":["libcamera-devel","v3","08/11"]}