From 8de411619a0ce05cc9f34f5a9f756908dbd21db8 Mon Sep 17 00:00:00 2001 From: Lorenz Meier Date: Sat, 24 Jan 2015 15:50:53 +0100 Subject: Initial stab at supporting multiple publications on the same base name and auto-enumeration of additional publications. --- ROMFS/px4fmu_test/init.d/rcS | 7 + src/drivers/drv_orb_dev.h | 9 +- src/modules/uORB/Publication.cpp | 2 +- src/modules/uORB/Publication.hpp | 2 +- src/modules/uORB/Subscription.cpp | 2 +- src/modules/uORB/Subscription.hpp | 2 +- src/modules/uORB/module.mk | 5 +- src/modules/uORB/objects_common.cpp | 2 +- src/modules/uORB/uORB.cpp | 260 ++++++++++++++++++++++++++---------- src/modules/uORB/uORB.h | 65 ++++++++- 10 files changed, 273 insertions(+), 83 deletions(-) diff --git a/ROMFS/px4fmu_test/init.d/rcS b/ROMFS/px4fmu_test/init.d/rcS index 40b3500e0..4b9a9b68a 100644 --- a/ROMFS/px4fmu_test/init.d/rcS +++ b/ROMFS/px4fmu_test/init.d/rcS @@ -97,6 +97,13 @@ else set unit_test_failure_list "${unit_test_failure_list} commander_tests" fi +if uorb test +then +else + set unit_test_failure 1 + set unit_test_failure_list "${unit_test_failure_list} uorb_tests" +fi + if hmc5883 -I start then # This is an FMUv3 diff --git a/src/drivers/drv_orb_dev.h b/src/drivers/drv_orb_dev.h index 713618545..e0b16fa5c 100644 --- a/src/drivers/drv_orb_dev.h +++ b/src/drivers/drv_orb_dev.h @@ -1,6 +1,6 @@ /**************************************************************************** * - * Copyright (C) 2012 PX4 Development Team. All rights reserved. + * Copyright (c) 2012-2015 PX4 Development Team. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -35,7 +35,9 @@ #define _DRV_UORB_H /** - * @file uORB published object driver. + * @file drv_orb_dev.h + * + * uORB published object driver. */ #include @@ -84,4 +86,7 @@ /** Get the global advertiser handle for the topic */ #define ORBIOCGADVERTISER _ORBIOC(13) +/** Get the priority for the topic */ +#define ORBIOCGPRIORITY _ORBIOC(14) + #endif /* _DRV_UORB_H */ diff --git a/src/modules/uORB/Publication.cpp b/src/modules/uORB/Publication.cpp index 71757e1f4..d33f93060 100644 --- a/src/modules/uORB/Publication.cpp +++ b/src/modules/uORB/Publication.cpp @@ -1,6 +1,6 @@ /**************************************************************************** * - * Copyright (C) 2012 PX4 Development Team. All rights reserved. + * Copyright (c) 2012-2015 PX4 Development Team. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions diff --git a/src/modules/uORB/Publication.hpp b/src/modules/uORB/Publication.hpp index 8650b3df8..b64559734 100644 --- a/src/modules/uORB/Publication.hpp +++ b/src/modules/uORB/Publication.hpp @@ -1,6 +1,6 @@ /**************************************************************************** * - * Copyright (C) 2012 PX4 Development Team. All rights reserved. + * Copyright (c) 2012-2015 PX4 Development Team. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions diff --git a/src/modules/uORB/Subscription.cpp b/src/modules/uORB/Subscription.cpp index 44b6debc7..8884e5a3a 100644 --- a/src/modules/uORB/Subscription.cpp +++ b/src/modules/uORB/Subscription.cpp @@ -1,6 +1,6 @@ /**************************************************************************** * - * Copyright (C) 2012 PX4 Development Team. All rights reserved. + * Copyright (c) 2012-2015 PX4 Development Team. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions diff --git a/src/modules/uORB/Subscription.hpp b/src/modules/uORB/Subscription.hpp index 34e9a83e0..75cf36254 100644 --- a/src/modules/uORB/Subscription.hpp +++ b/src/modules/uORB/Subscription.hpp @@ -1,6 +1,6 @@ /**************************************************************************** * - * Copyright (C) 2012 PX4 Development Team. All rights reserved. + * Copyright (c) 2012-2015 PX4 Development Team. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions diff --git a/src/modules/uORB/module.mk b/src/modules/uORB/module.mk index 9385ce253..71ad09130 100644 --- a/src/modules/uORB/module.mk +++ b/src/modules/uORB/module.mk @@ -1,6 +1,6 @@ ############################################################################ # -# Copyright (c) 2012, 2013 PX4 Development Team. All rights reserved. +# Copyright (c) 2012-2015 PX4 Development Team. All rights reserved. # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions @@ -37,8 +37,7 @@ MODULE_COMMAND = uorb -# XXX probably excessive, 2048 should be sufficient -MODULE_STACKSIZE = 4096 +MODULE_STACKSIZE = 2048 SRCS = uORB.cpp \ objects_common.cpp \ diff --git a/src/modules/uORB/objects_common.cpp b/src/modules/uORB/objects_common.cpp index 78fdf4de7..20a9bcc43 100644 --- a/src/modules/uORB/objects_common.cpp +++ b/src/modules/uORB/objects_common.cpp @@ -1,6 +1,6 @@ /**************************************************************************** * - * Copyright (C) 2012-2014 PX4 Development Team. All rights reserved. + * Copyright (c) 2012-2015 PX4 Development Team. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions diff --git a/src/modules/uORB/uORB.cpp b/src/modules/uORB/uORB.cpp index 3373aac83..cfea12f04 100644 --- a/src/modules/uORB/uORB.cpp +++ b/src/modules/uORB/uORB.cpp @@ -1,6 +1,6 @@ /**************************************************************************** * - * Copyright (Cc) 2012-2015 PX4 Development Team. All rights reserved. + * Copyright (c) 2012-2015 PX4 Development Team. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -51,6 +51,7 @@ #include #include #include +#include #include #include @@ -68,6 +69,7 @@ namespace { +/* internal use only */ static const unsigned orb_maxpath = 64; /* oddly, ERROR is not defined for c++ */ @@ -81,17 +83,30 @@ enum Flavor { PARAM }; +struct orb_advertdata { + const struct orb_metadata *meta; + int *instance; + int priority; +}; + int -node_mkpath(char *buf, Flavor f, const struct orb_metadata *meta) +node_mkpath(char *buf, Flavor f, const struct orb_metadata *meta, int *instance = nullptr) { unsigned len; - len = snprintf(buf, orb_maxpath, "/%s/%s", - (f == PUBSUB) ? "obj" : "param", - meta->o_name); + unsigned index = 0; + + if (instance != nullptr) { + index = *instance; + } + + len = snprintf(buf, orb_maxpath, "/%s/%s%d", + (f == PUBSUB) ? "obj" : "param", + meta->o_name, index); - if (len >= orb_maxpath) + if (len >= orb_maxpath) { return -ENAMETOOLONG; + } return OK; } @@ -104,7 +119,7 @@ node_mkpath(char *buf, Flavor f, const struct orb_metadata *meta) class ORBDevNode : public device::CDev { public: - ORBDevNode(const struct orb_metadata *meta, const char *name, const char *path); + ORBDevNode(const struct orb_metadata *meta, const char *name, const char *path, int priority); ~ORBDevNode(); virtual int open(struct file *filp); @@ -126,6 +141,7 @@ private: struct hrt_call update_call; /**< deferred wakeup call if update_period is nonzero */ void *poll_priv; /**< saved copy of fds->f_priv while poll is active */ bool update_reported; /**< true if we have reported the update via poll/check */ + int priority; /**< priority of publisher */ }; const struct orb_metadata *_meta; /**< object metadata information */ @@ -133,6 +149,7 @@ private: hrt_abstime _last_update; /**< time the object was last updated */ volatile unsigned _generation; /**< object generation count */ pid_t _publisher; /**< if nonzero, current publisher */ + const int _priority; /**< priority of topic */ SubscriberData *filp_to_sd(struct file *filp) { SubscriberData *sd = (SubscriberData *)(filp->f_priv); @@ -160,13 +177,14 @@ private: bool appears_updated(SubscriberData *sd); }; -ORBDevNode::ORBDevNode(const struct orb_metadata *meta, const char *name, const char *path) : +ORBDevNode::ORBDevNode(const struct orb_metadata *meta, const char *name, const char *path, int priority) : CDev(name, path), _meta(meta), _data(nullptr), _last_update(0), _generation(0), - _publisher(0) + _publisher(0), + _priority(priority) { // enable debug() calls _debug_enabled = true; @@ -176,6 +194,7 @@ ORBDevNode::~ORBDevNode() { if (_data != nullptr) delete[] _data; + } int @@ -225,6 +244,9 @@ ORBDevNode::open(struct file *filp) /* default to no pending update */ sd->generation = _generation; + /* set priority */ + sd->priority = _priority; + filp->f_priv = (void *)sd; ret = CDev::open(filp); @@ -283,6 +305,9 @@ ORBDevNode::read(struct file *filp, char *buffer, size_t buflen) /* track the last generation that the file has seen */ sd->generation = _generation; + /* set priority */ + sd->priority = _priority; + /* * Clear the flag that indicates that an update has been reported, as * we have just collected it. @@ -364,6 +389,10 @@ ORBDevNode::ioctl(struct file *filp, int cmd, unsigned long arg) *(uintptr_t *)arg = (uintptr_t)this; return OK; + case ORBIOCGPRIORITY: + *(int *)arg = sd->priority; + return OK; + default: /* give it to the superclass */ return CDev::ioctl(filp, cmd, arg); @@ -556,40 +585,73 @@ ORBDevMaster::ioctl(struct file *filp, int cmd, unsigned long arg) switch (cmd) { case ORBIOCADVERTISE: { - const struct orb_metadata *meta = (const struct orb_metadata *)arg; + const struct orb_advertdata *adv = (const struct orb_advertdata *)arg; + const struct orb_metadata *meta = adv->meta; const char *objname; + const char *devpath; char nodepath[orb_maxpath]; ORBDevNode *node; /* construct a path to the node - this also checks the node name */ - ret = node_mkpath(nodepath, _flavor, meta); + ret = node_mkpath(nodepath, _flavor, meta, adv->instance); - if (ret != OK) + if (ret != OK) { return ret; + } /* driver wants a permanent copy of the node name, so make one here */ objname = strdup(meta->o_name); - if (objname == nullptr) + if (objname == nullptr) { return -ENOMEM; + } - /* construct the new node */ - node = new ORBDevNode(meta, objname, nodepath); + /* ensure that only one advertiser runs through this critical section */ + lock(); - /* initialise the node - this may fail if e.g. a node with this name already exists */ - if (node != nullptr) + ret = ERROR; + + /* try for topic groups */ + const unsigned max_group_tries = (adv->instance != nullptr) ? ORB_MULTI_MAX_INSTANCES : 1; + unsigned group_tries = 0; + do { + /* if path is modifyable change try index */ + if (adv->instance != nullptr) { + /* replace the number at the end of the string */ + nodepath[strlen(nodepath) - 1] = '0' + group_tries; + *(adv->instance) = group_tries; + } + + /* driver wants a permanent copy of the path, so make one here */ + devpath = strdup(nodepath); + + /* construct the new node */ + node = new ORBDevNode(meta, objname, devpath, adv->priority); + + /* if we didn't get a device, that's bad */ + if (node == nullptr) { + unlock(); + return -ENOMEM; + } + + /* initialise the node - this may fail if e.g. a node with this name already exists */ ret = node->init(); + + /* if init failed, discard the node and its name */ + if (ret != OK) { + delete node; + free((void *)objname); + } - /* if we didn't get a device, that's bad */ - if (node == nullptr) - return -ENOMEM; + } while (ret != OK && (group_tries++ < max_group_tries)); - /* if init failed, discard the node and its name */ - if (ret != OK) { - delete node; - free((void *)objname); + if (group_tries >= max_group_tries) { + ret = -ENOMEM; } + /* the file handle for the driver has been created, unlock */ + unlock(); + return ret; } @@ -614,6 +676,7 @@ struct orb_test { }; ORB_DEFINE(orb_test, struct orb_test); +ORB_DEFINE(orb_multitest, struct orb_test); int test_fail(const char *fmt, ...) @@ -643,8 +706,6 @@ test_note(const char *fmt, ...) return OK; } -ORB_DECLARE(sensor_combined); - int test() { @@ -700,48 +761,65 @@ test() orb_unsubscribe(sfd); close(pfd); -#if 0 - /* this is a hacky test that exploits the sensors app to test rate-limiting */ + /* this routine tests the multi-topic support */ + test_note("try multi-topic support"); - sfd = orb_subscribe(ORB_ID(sensor_combined)); + int instance0; + int pfd0 = orb_advertise_multi(ORB_ID(orb_multitest), &t, &instance0, ORB_PRIO_MAX); - hrt_abstime start, end; - unsigned count; + test_note("advertised"); + usleep(300000); - start = hrt_absolute_time(); - count = 0; + int instance1; + int pfd1 = orb_advertise_multi(ORB_ID(orb_multitest), &t, &instance1, ORB_PRIO_MIN); - do { - orb_check(sfd, &updated); + if (instance0 != 0) + return test_fail("mult. id0: %d", instance0); - if (updated) { - orb_copy(ORB_ID(sensor_combined), sfd, nullptr); - count++; - } - } while (count < 100); + if (instance1 != 1) + return test_fail("mult. id1: %d", instance1); - end = hrt_absolute_time(); - test_note("full-speed, 100 updates in %llu", end - start); + t.val = 103; + if (OK != orb_publish(ORB_ID(orb_multitest), pfd0, &t)) + return test_fail("mult. pub0 fail"); - orb_set_interval(sfd, 10); + test_note("published"); + usleep(300000); - start = hrt_absolute_time(); - count = 0; + t.val = 203; + if (OK != orb_publish(ORB_ID(orb_multitest), pfd1, &t)) + return test_fail("mult. pub1 fail"); - do { - orb_check(sfd, &updated); + /* subscribe to both topics and ensure valid data is received */ + int sfd0 = orb_subscribe_multi(ORB_ID(orb_multitest), 0); - if (updated) { - orb_copy(ORB_ID(sensor_combined), sfd, nullptr); - count++; - } - } while (count < 100); + if (OK != orb_copy(ORB_ID(orb_multitest), sfd0, &t)) + return test_fail("sub #0 copy failed: %d", errno); - end = hrt_absolute_time(); - test_note("100Hz, 100 updates in %llu", end - start); + if (t.val != 103) + return test_fail("sub #0 val. mismatch: %d", t.val); - orb_unsubscribe(sfd); -#endif + int sfd1 = orb_subscribe_multi(ORB_ID(orb_multitest), 1); + + if (OK != orb_copy(ORB_ID(orb_multitest), sfd1, &t)) + return test_fail("sub #1 copy failed: %d", errno); + + if (t.val != 203) + return test_fail("sub #1 val. mismatch: %d", t.val); + + /* test priorities */ + int prio; + if (OK != orb_priority(sfd0, &prio)) + return test_fail("prio #0"); + + if (prio != ORB_PRIO_MAX) + return test_fail("prio: %d", prio); + + if (OK != orb_priority(sfd1, &prio)) + return test_fail("prio #1"); + + if (prio != ORB_PRIO_MIN) + return test_fail("prio: %d", prio); return test_note("PASS"); } @@ -771,7 +849,7 @@ uorb_main(int argc, char *argv[]) if (!strcmp(argv[1], "start")) { if (g_dev != nullptr) { - fprintf(stderr, "[uorb] already loaded\n"); + warnx("already loaded"); /* user wanted to start uorb, its already running, no error */ return 0; } @@ -780,18 +858,17 @@ uorb_main(int argc, char *argv[]) g_dev = new ORBDevMaster(PUBSUB); if (g_dev == nullptr) { - fprintf(stderr, "[uorb] driver alloc failed\n"); + warnx("driver alloc failed"); return -ENOMEM; } if (OK != g_dev->init()) { - fprintf(stderr, "[uorb] driver init failed\n"); + warnx("driver init failed"); delete g_dev; g_dev = nullptr; return -EIO; } - printf("[uorb] ready\n"); return OK; } @@ -807,8 +884,7 @@ uorb_main(int argc, char *argv[]) if (!strcmp(argv[1], "status")) return info(); - fprintf(stderr, "unrecognised command, try 'start', 'test' or 'status'\n"); - return -EINVAL; + errx(-EINVAL, "unrecognized command, try 'start', 'test' or 'status'"); } /* @@ -825,11 +901,14 @@ namespace * we tried to advertise. */ int -node_advertise(const struct orb_metadata *meta) +node_advertise(const struct orb_metadata *meta, int *instance = nullptr, int priority = ORB_PRIO_DEFAULT) { int fd = -1; int ret = ERROR; + /* fill advertiser data */ + const struct orb_advertdata adv = { meta, instance, priority }; + /* open the control device */ fd = open(TOPIC_MASTER_DEVICE_PATH, 0); @@ -837,11 +916,12 @@ node_advertise(const struct orb_metadata *meta) goto out; /* advertise the object */ - ret = ioctl(fd, ORBIOCADVERTISE, (unsigned long)(uintptr_t)meta); + ret = ioctl(fd, ORBIOCADVERTISE, (unsigned long)(uintptr_t)&adv); /* it's OK if it already exists */ - if ((OK != ret) && (EEXIST == errno)) + if ((OK != ret) && (EEXIST == errno)) { ret = OK; + } out: @@ -858,7 +938,7 @@ out: * advertisers. */ int -node_open(Flavor f, const struct orb_metadata *meta, const void *data, bool advertiser) +node_open(Flavor f, const struct orb_metadata *meta, const void *data, bool advertiser, int *instance = nullptr, int priority = ORB_PRIO_DEFAULT) { char path[orb_maxpath]; int fd, ret; @@ -883,7 +963,7 @@ node_open(Flavor f, const struct orb_metadata *meta, const void *data, bool adve /* * Generate the path to the node and try to open it. */ - ret = node_mkpath(path, f, meta); + ret = node_mkpath(path, f, meta, instance); if (ret != OK) { errno = -ret; @@ -893,15 +973,34 @@ node_open(Flavor f, const struct orb_metadata *meta, const void *data, bool adve /* open the path as either the advertiser or the subscriber */ fd = open(path, (advertiser) ? O_WRONLY : O_RDONLY); + /* if we want to advertise and the node existed, we have to re-try again */ + if ((fd >= 0) && (instance != nullptr) && (advertiser)) { + /* close the fd, we want a new one */ + close(fd); + /* the node_advertise call will automatically go for the next free entry */ + fd = -1; + } + /* we may need to advertise the node... */ if (fd < 0) { /* try to create the node */ - ret = node_advertise(meta); + ret = node_advertise(meta, instance, priority); + + if (ret == OK) { + /* update the path, as it might have been updated during the node_advertise call */ + ret = node_mkpath(path, f, meta, instance); + + if (ret != OK) { + errno = -ret; + return ERROR; + } + } /* on success, try the open again */ - if (ret == OK) + if (ret == OK) { fd = open(path, (advertiser) ? O_WRONLY : O_RDONLY); + } } if (fd < 0) { @@ -917,12 +1016,18 @@ node_open(Flavor f, const struct orb_metadata *meta, const void *data, bool adve orb_advert_t orb_advertise(const struct orb_metadata *meta, const void *data) +{ + return orb_advertise_multi(meta, data, nullptr, ORB_PRIO_DEFAULT); +} + +orb_advert_t +orb_advertise_multi(const struct orb_metadata *meta, const void *data, int *instance, int priority) { int result, fd; orb_advert_t advertiser; /* open the node as an advertiser */ - fd = node_open(PUBSUB, meta, data, true); + fd = node_open(PUBSUB, meta, data, true, instance, priority); if (fd == ERROR) return ERROR; @@ -933,7 +1038,7 @@ orb_advertise(const struct orb_metadata *meta, const void *data) return ERROR; /* the advertiser must perform an initial publish to initialise the object */ - result= orb_publish(meta, advertiser, data); + result = orb_publish(meta, advertiser, data); if (result == ERROR) return ERROR; @@ -946,6 +1051,13 @@ orb_subscribe(const struct orb_metadata *meta) return node_open(PUBSUB, meta, nullptr, false); } +int +orb_subscribe_multi(const struct orb_metadata *meta, unsigned instance) +{ + int inst = instance; + return node_open(PUBSUB, meta, nullptr, false, &inst); +} + int orb_unsubscribe(int handle) { @@ -988,6 +1100,12 @@ orb_stat(int handle, uint64_t *time) return ioctl(handle, ORBIOCLASTUPDATE, (unsigned long)(uintptr_t)time); } +int +orb_priority(int handle, int *priority) +{ + return ioctl(handle, ORBIOCGPRIORITY, (unsigned long)(uintptr_t)priority); +} + int orb_set_interval(int handle, unsigned interval) { diff --git a/src/modules/uORB/uORB.h b/src/modules/uORB/uORB.h index beb23f61d..a0ad75273 100644 --- a/src/modules/uORB/uORB.h +++ b/src/modules/uORB/uORB.h @@ -1,6 +1,6 @@ /**************************************************************************** * - * Copyright (C) 2012 PX4 Development Team. All rights reserved. + * Copyright (c) 2012-2015 PX4 Development Team. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -56,6 +56,25 @@ struct orb_metadata { typedef const struct orb_metadata *orb_id_t; +/** + * Maximum number of multi topic instances + */ +#define ORB_MULTI_MAX_INSTANCES 4 + +/** + * Topic priority. + * Relevant for multi-topics / topic groups + */ +enum ORB_PRIO { + ORB_PRIO_MIN = 0, + ORB_PRIO_VERY_LOW = 25, + ORB_PRIO_LOW = 50, + ORB_PRIO_DEFAULT = 75, + ORB_PRIO_HIGH = 100, + ORB_PRIO_VERY_HIGH = 125, + ORB_PRIO_MAX = 255 +}; + /** * Generates a pointer to the uORB metadata structure for * a given topic. @@ -128,7 +147,7 @@ typedef const struct orb_metadata *orb_id_t; #define ORB_DEFINE(_name, _struct) \ const struct orb_metadata __orb_##_name = { \ #_name, \ - sizeof(_struct) \ + sizeof(_struct), \ }; struct hack __BEGIN_DECLS @@ -167,6 +186,34 @@ typedef intptr_t orb_advert_t; */ extern orb_advert_t orb_advertise(const struct orb_metadata *meta, const void *data) __EXPORT; +/** + * Advertise as the publisher of a topic. + * + * This performs the initial advertisement of a topic; it creates the topic + * node in /obj if required and publishes the initial data. + * + * Any number of advertisers may publish to a topic; publications are atomic + * but co-ordination between publishers is not provided by the ORB. + * + * @param meta The uORB metadata (usually from the ORB_ID() macro) + * for the topic. + * @param data A pointer to the initial data to be published. + * For topics updated by interrupt handlers, the advertisement + * must be performed from non-interrupt context. + * @param instance Pointer to an integer which will yield the instance ID (0-based) + * of the publication. + * @param priority The priority of the instance. If a subscriber subscribes multiple + * instances, the priority allows the subscriber to prioritize the best + * data source as long as its available. + * @return ERROR on error, otherwise returns a handle + * that can be used to publish to the topic. + * If the topic in question is not known (due to an + * ORB_DEFINE with no corresponding ORB_DECLARE) + * this function will return -1 and set errno to ENOENT. + */ +extern orb_advert_t orb_advertise_multi(const struct orb_metadata *meta, const void *data, int *instance, int priority) __EXPORT; + + /** * Publish new data to a topic. * @@ -210,6 +257,8 @@ extern int orb_publish(const struct orb_metadata *meta, orb_advert_t handle, con */ extern int orb_subscribe(const struct orb_metadata *meta) __EXPORT; +extern int orb_subscribe_multi(const struct orb_metadata *meta, unsigned instance) __EXPORT; + /** * Unsubscribe from a topic. * @@ -266,6 +315,18 @@ extern int orb_check(int handle, bool *updated) __EXPORT; */ extern int orb_stat(int handle, uint64_t *time) __EXPORT; +/** + * Return the priority of the topic + * + * @param handle A handle returned from orb_subscribe. + * @param priority Returns the priority of this topic. This is only relevant for + * topics which are published by multiple publishers (e.g. mag0, mag1, etc.) + * and allows a subscriber to automatically pick the topic with the highest + * priority, independent of the startup order of the associated publishers. + * @return OK on success, ERROR otherwise with errno set accordingly. + */ +extern int orb_priority(int handle, int *priority) __EXPORT; + /** * Set the minimum interval between which updates are seen for a subscription. * -- cgit v1.2.3