[finger563]

Summary

Follow-up to #870, which added the last capacity cap to the override mechanism. This exposes the remaining profile constants the engine actually reads - discovery and reliability timing, the task priorities and stacks, one more capacity cap, and the domain id - as menuconfig knobs with the same RTPS_CFG_<NAME> pattern, and accepts the same names in the host build's -DRTPS_LIMIT_OVERRIDES list. No default changes, no wire-format change: these alter only when discovery and reliability messages are sent and how the engine's tasks are scheduled.

Rebased onto main after #870 merged (its constant kept as merged: uint16_t on the host profiles).

New knobs

0 = profile default for all but the domain id, where 0 is the DDS default domain.

menuconfig	constant	embedded / host / host_large	what it does
RTPS -> Domain id (RTPS_DOMAIN_ID, 0..232)	DOMAIN_ID	0 / 0 / 0	DDS domain (the ROS_DOMAIN_ID equivalent). The port base 7400 + 250 * id and GUID prefix byte 9 derive from it, so every participant on a domain must use the same value. Compile-time, shared by all participants in the firmware.
Custom capacity overrides: RTPS_LIMIT_SPDP_MAX_NUM_LOCATORS	SPDP_MAX_NUM_LOCATORS	1 / 8 / 16	Locators kept per list of a remote participant proxy (4 lists per proxy, 12 bytes per locator, times SPDP_MAX_NUMBER_FOUND_PARTICIPANTS). 1 already reaches a multi-homed peer since #866 prefers the locator on our network.
Discovery and reliability timing: RTPS_SPDP_RESEND_PERIOD_MS	SPDP_RESEND_PERIOD_MS	2000 / 1000 / 1000	Participant announcement period.
RTPS_SPDP_CYCLECOUNT_HEARTBEAT	SPDP_CYCLECOUNT_HEARTBEAT	2 / 2 / 2	Remote liveliness is checked every (n + 1) announce rounds.
RTPS_SF_WRITER_HB_PERIOD_MS	SF_WRITER_HB_PERIOD_MS	4000 / 2000 / 2000	RELIABLE writer HEARTBEAT period; a quarter of it while a reader has unacknowledged changes.
RTPS_SPDP_DEFAULT_REMOTE_LEASE_DURATION_S	SPDP_DEFAULT_REMOTE_LEASE_DURATION (seconds)	5 / 100 / 100	The lease we announce for ourselves, and the lease assumed for a peer that announces none.
RTPS_SPDP_MAX_REMOTE_LEASE_DURATION_S	SPDP_MAX_REMOTE_LEASE_DURATION (seconds)	90 / 180 / 180	Cap on a remote lease: a silent peer is dropped after min(its lease, this).
Tasks (was "Transport task priority"): RTPS_THREAD_POOL_READER_PRIO	THREAD_POOL_READER_PRIO	5 / 3 / 3	unchanged
RTPS_THREAD_POOL_READER_STACKSIZE	THREAD_POOL_READER_STACKSIZE	6144 / 1600 / 1600	Stack of the worker pool and reactor tasks (they run every reader and matched callback). Below 2048 is refused at build time.
RTPS_SPDP_WRITER_PRIO	SPDP_WRITER_PRIO	5 / 3 / 3	Priority of the protocol task (rtps_protocol: announcements, HEARTBEATs, liveliness).
RTPS_SPDP_WRITER_STACKSIZE	SPDP_WRITER_STACKSIZE	4096 / 550 / 550	Stack of the protocol task; the engine raises anything below 4096 to 4096, below 2048 is refused at build time.

The help texts state the relations that must hold: the announced lease must comfortably exceed the announcement period (peers drop a participant whose announcements they miss for a whole lease; 2-3 announcements per lease); the liveliness check runs every (SPDP_CYCLECOUNT_HEARTBEAT + 1) * SPDP_RESEND_PERIOD_MS, so a vanished peer lingers up to that long past its lease; a remote lease cap below a peer's announcement period drops that peer while it is alive.

Mechanics

• Profile headers: each constant gets the #ifndef RTPS_CFG_X default block, values unchanged. The two leases are expressed in whole seconds ({RTPS_CFG_..._S, 0}).
• components/rtps/CMakeLists.txt: SPDP_MAX_NUM_LOCATORS joins RTPS_LIMIT_KNOBS; a new RTPS_TUNING_KNOBS loop maps CONFIG_RTPS_<knob> (nonzero) to RTPS_CFG_<knob> and subsumes the previous THREAD_POOL_READER_PRIO special case; RTPS_DOMAIN_ID is always passed through (0 is a real value).
• lib/espp.cmake: the names are accepted in RTPS_LIMIT_OVERRIDES with per-type ranges (uint8, uint16 on every profile, int stacks, lease seconds, domain id 0..232) and the stack minimum; THREAD_POOL_READER_PRIO becomes host-overridable too.
• README: the configuration table lists the new options; the facade header's note on compile-time domain id / periods points at the knobs.

Deliberately not exposed

SPDP_LEASE_DURATION, THREAD_POOL_NUM_WRITERS/READERS, THREAD_POOL_WORKLOAD_QUEUE_LENGTH_*, HEARTBEAT_STACKSIZE, THREAD_POOL_WRITER_PRIO/STACKSIZE and OVERALL_HEAP_SIZE are defined in the profile headers but nothing in the engine reads them (leftovers of the original per-writer threads). A knob for them would do nothing; they are left as they are and could be removed in a cleanup.

Test plan

• components/rtps/example builds for esp32 (IDF 6.1, component manager off) with defaults; every new CONFIG_RTPS_* symbol is generated at 0 (domain id 0)
• Same example with CONFIG_RTPS_DOMAIN_ID=5, CONFIG_RTPS_SPDP_DEFAULT_REMOTE_LEASE_DURATION_S=20, CONFIG_RTPS_THREAD_POOL_READER_STACKSIZE=8192, CONFIG_RTPS_LIMIT_SPDP_MAX_NUM_LOCATORS=4, CONFIG_RTPS_SPDP_RESEND_PERIOD_MS=500, CONFIG_RTPS_SPDP_WRITER_PRIO=7: builds, and compile_commands.json shows the six RTPS_CFG_*= definitions on every rtps source AND on the example's own translation unit
• Host library (lib, host profile) with no overrides, installed; pc tests rtps_golden (byte-identical vectors), rtps_locator_subnet, rtps_sedp_dedicated_locator, rtps_pubsub pass
• Host library with -DRTPS_LIMIT_OVERRIDES="SPDP_MAX_NUM_LOCATORS=4;SPDP_RESEND_PERIOD_MS=500;DOMAIN_ID=3;THREAD_POOL_READER_STACKSIZE=65536" configures (each override reported) and builds; DOMAIN_ID=300 and SPDP_WRITER_STACKSIZE=1024 are refused as out of range
• clang-format (pre-commit) on the touched headers; no .cpp changed, so nothing for cppcheck
• CI

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[Copilot]

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Copilot review overview

4 open issues

• The section header says these are “pure capacity caps”, but DOMAIN_ID is introduced immediately… · New
• The comment says the engine/domain raises any SPDP_WRITER_STACKSIZE below 4096 up to 4096, but… · New
• This comment is now inaccurate/misleading: RTPS_LIMIT_OVERRIDES is expanded to cover non-capacity… · New
• The host-side override validation now enforces a 2048-byte minimum for… · New

What changed in this PR

Exposes additional RTPS profile “constants” (discovery/reliability timing, task priorities/stack sizes, locator caps, and domain id) as build-time knobs via ESP-IDF menuconfig and the host build’s RTPS_LIMIT_OVERRIDES, without changing defaults or wire format.

Changes:

• Added new Kconfig options and CMake plumbing to map CONFIG_RTPS_* to RTPS_CFG_* compile definitions.
• Extended host-build override parsing/validation (RTPS_LIMIT_OVERRIDES) to accept the new tuning and domain-id constants.
• Updated profile headers and documentation to support the new RTPS_CFG_* override blocks.

File	Description
lib/​espp.cmake	Extends override mechanism beyond capacity caps to timing/tasks/domain id; adds per-type validation.
components/​rtps/​CMakeLists.txt	Wires new Kconfig knobs into RTPS_CFG_* compile definitions and adds basic validation.
components/​rtps/​Kconfig	Adds menuconfig knobs for discovery timing, task settings, domain id, and extra capacity caps.
components/​rtps/​include/​rtps/​config_desktop.hpp	Converts several fixed constants (domain id/timing/stacks/etc.) to RTPS_CFG_* overridable defaults.
components/​rtps/​include/​rtps/​config_host_large.hpp	Same as above for host_large profile.
components/​rtps/​include/​rtps/​config_esp32.hpp	Same as above for esp32 profile (ESP-IDF).
components/​rtps/​include/​rtps_participant.hpp	Updates limitations doc to reflect build-time configurability via new knobs.
components/​rtps/​README.md	Documents new configuration knobs and clarifies override mechanism scope.

_{Review effort: Lite}

[github-actions]

✅Static analysis result - no issues found! ✅

[finger563]

Rebased onto main now that #870 and #871 are merged; the PR no longer carries #870's diff. Three conflicts, all one cause: the merged #870 widened SPDP_MAX_NUMBER_FOUND_PARTICIPANTS to uint16_t on the host profiles (with its comment) and lists it among the uint16 host knobs. Kept main's version of that constant and its validation; the new knobs sit next to it unchanged.

Re-verified after the rebase: host library builds, rtps_golden / rtps_locator_subnet / rtps_pubsub pass, an override configure accepts SPDP_MAX_NUM_LOCATORS=4;SPDP_RESEND_PERIOD_MS=500;DOMAIN_ID=3;SPDP_WRITER_STACKSIZE=550;SPDP_MAX_NUMBER_FOUND_PARTICIPANTS=300; the esp32 example builds with four knobs set and the RTPS_CFG_* values reach the compiler.

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[finger563]

Config constant audit (every rtps::Config constant, all three profiles)

Each constant was checked for (1) value/type/comment, (2) every use site (grep over components/rtps, lib/, pc/, lib/python_bindings, docs, Kconfig, CMake), (3) correctness at each use (units, type widths vs counters, pool bounds, Duration_t from seconds, FreeRTOS priority semantics, stack sizes applied by espp::Task on ESP only), (4) cross-profile consistency and (5) agreement with this PR's Kconfig ranges / lib/espp.cmake validation. Fixes landed as one extra commit (17ddebc); no default value or wire format changed.

Type/value columns are esp32 / host / host_large. "k" = exposed as a knob by this PR.

Constant	Type	Value	Use sites	Verdict
VENDOR_ID	VendorId_t	{13,37} all	MessageFactory.hpp:51 (header), SPDPAgent.cpp:243,272 (announce), Domain.cpp:967,993 (GUID prefix bytes 7-8)	OK, wire identity. Kept, comment added.
IP_ADDRESS	std::array<uint8_t,4>	{192,168,4,1} all	only the 2-arg Participant::reuse(), which has no caller (Domain.cpp:344 uses the 4-arg overload with the real interface address)	Dead, removed together with the overload. The desktop comment ("set in lwipcfg.h too") was stale.
BASE_GUID_PREFIX	GuidPrefix_t	fixed / GUID_RANDOM / GUID_RANDOM	Domain.cpp:976-986 only on the non-MAC path; on ESP the Ethernet/Wi-Fi MAC path returns first; bytes 6-9 always overwritten (id, vendor, domain)	OK. Deliberate profile difference; esp32 comment now says it is only the no-MAC fallback and that two fallback boards collide.
DOMAIN_ID k	uint8_t	0 all	udpUtils.hpp:51-92 (port math 7400 + 250*id + ...), Domain.cpp:531 (dedicated port base), Domain.cpp:969,995 (prefix byte 9), 2 pc tests	OK. Kconfig/host max 232 matches the UDP port budget; the sentinel is not used for it (always defined), so a real 0 is fine.
MAX_SAMPLE_SIZE	DataSize_t	256 KB / 8 MB / 8 MB	Reader.cpp:75-77 (drop fragmented sample > max)	OK, fed from RTPS_MAX_SAMPLE_SIZE (CMake per profile).
NUM_STATELESS_WRITERS/READERS k	uint8_t	5 / 16 / 64	Domain.hpp:209-212 std::array pools; rtps_participant.cpp:316-393 messages	OK. CMake cross-check (>= participants, 1 SPDP W/R each) matches Domain.
NUM_STATEFUL_WRITERS/READERS k	uint8_t	5 / 32 / 128	Domain.hpp:209-212; messages	OK. Cross-check (>= 2 x participants for SEDP) matches.
MAX_NUM_PARTICIPANTS k	uint8_t	1 / 8 / 32	Domain.hpp:123 array, Domain.cpp:363,378; m_numParticipants is uint8_t	OK (255 cap keeps the counter from wrapping).
NUM_WRITERS/READERS_PER_PARTICIPANT k	uint8_t	10 / 16 / 64	Participant.hpp:133-134 arrays; messages (3 builtins each)	OK; CMake minimum 3 cites the real builtin count.
NUM_WRITER_PROXIES_PER_READER / NUM_READER_PROXIES_PER_WRITER k	uint8_t	6 / 8 / 16	Reader.hpp:178, Writer.hpp:160 MemoryPool (uint32 SIZE, uint32 bit index)	OK.
MAX_NUM_UNMATCHED_REMOTE_WRITERS/READERS k	uint8_t / uint16_t / uint16_t	50,50 / 256,128 / 1024,512	SEDPAgent.hpp:86,89 MemoryPool	OK; widening is deliberate (#870) and espp.cmake RTPS_LIMIT_UINT16_KNOBS allows 65535 only off embedded.
MAX_NUM_READER_CALLBACKS k	uint8_t	5 / 8 / 16	Reader.hpp:205 array	OK.
HISTORY_SIZE_STATELESS / _STATEFUL k	uint8_t	2,10 / 8,16 / 32,32	StatelessWriter.hpp:68, StatefulWriter.hpp:82 (template <uint16_t SIZE>)	OK (uint8 into uint16 template).
MAX_TYPENAME_LENGTH / MAX_TOPICNAME_LENGTH k	uint8_t	64 all	TopicData.hpp:49-50 char arrays, :128; TopicData.cpp:113,130 receive (len > MAX reject, len includes the CDR NUL), :236,250 serialize (strlen+1); create path Domain.cpp:738-745,822-829 and rtps_participant.cpp:302-307 reject strlen >= MAX	OK and consistent (63 chars + NUL both ways). See open question 1.
THREAD_POOL_READER_STACKSIZE k	int	6144 / 1600 / 1600	EsppTransport.cpp:90,99 worker pool + reactor stack_size_bytes	OK. Bytes; applied on ESP only (esp_pthread); host std::thread ignores it. Kconfig 0..65535, CMake FATAL below 2048.
SPDP_WRITER_STACKSIZE k	uint16_t	4096 / 550 / 550	Domain.cpp:104 (> 4096 ? v : 4096) protocol task	OK; comment states the clamp and the ESP-only effect. uint16 matches the 65535 Kconfig/host max.
SF_WRITER_HB_PERIOD_MS k	uint16_t	4000 / 2000 / 2000	StatefulWriter.cpp:588-590 as std::chrono::milliseconds (/4 while unacked)	OK, ms. Kconfig/host 0..65535 = uint16.
SPDP_RESEND_PERIOD_MS k	uint16_t	2000 / 1000 / 1000	Domain.cpp:158 ms cadence of the protocol task	OK, ms.
SPDP_CYCLECOUNT_HEARTBEAT k	uint8_t	2 all	SPDPAgent.cpp:68 (m_cycleHB == count, m_cycleHB is uint8_t from 0)	OK: liveliness checked every (count+1) announce rounds, as the comment says; 255 cannot overflow the counter. See open question 2.
SPDP_WRITER_PRIO k	uint8_t	5 / 3 / 3	Domain.cpp:105	OK. Kconfig 0..24 = FreeRTOS configMAX_PRIORITIES-1; the 0 sentinel only hides idle priority.
THREAD_POOL_READER_PRIO k	int	5 / 3 / 3	EsppTransport.cpp:91,100	OK, same range. Comment pointed at a non-existent "Transport task priority" menu; now "RTPS -> Tasks".
SPDP_MAX_NUMBER_FOUND_PARTICIPANTS k	uint8_t / uint16_t / uint16_t	10 / 32 / 128	Participant.hpp:137 MemoryPool	OK (#870 widening).
SPDP_MAX_NUM_LOCATORS k	uint8_t	1 / 8 / 16	ParticipantProxyData.hpp:59-62,90, .cpp:49,227, pc/tests/rtps_locator_subnet.cpp	OK; loop index is int. Comment's 4 lists x 12 bytes per slot is right.
SPDP_DEFAULT_REMOTE_LEASE_DURATION k (_S)	Duration_t	{5,0} / {100,0} / {100,0}	ParticipantProxyData.hpp:64 proxy default, SPDPAgent.cpp:289-290 our own announcement	OK: {seconds, fraction=0} from the knob; Kconfig/host 0..3600 fits int32 seconds. Relation "> resend period" holds in every profile (5 s vs 2 s, 100 s vs 1 s).
SPDP_MAX_REMOTE_LEASE_DURATION k (_S)	Duration_t	{90,0} / {180,0} / {180,0}	ParticipantProxyData.hpp:isAlive() min(remote lease, this) in ms	Value OK (default <= max in every profile). The ms conversion did int32 seconds * 1000 on the peer-supplied lease: UB above ~24.8 days, and a negative lease wrapped to a huge unsigned value. Fixed: widened to uint64, negative counts as 0.
MAX_NUM_UDP_CONNECTIONS k	int	10 / 24 / 72	EsppTransport.hpp:168 std::array<Channel, N>	OK; CMake minimum 4 and the 2 + 2*participants cross-check match Domain.
SPDP_LEASE_DURATION	Duration_t	{5,0} esp32 only	none	Dead, removed (the announced lease is SPDP_DEFAULT_REMOTE_LEASE_DURATION).
HEARTBEAT_STACKSIZE	int	6144 / 1200 / 1200	none	Dead, removed (heartbeats run on the protocol task).
THREAD_POOL_WRITER_STACKSIZE	int	4096 / 1100 / 1100	none	Dead, removed (writers send inline; no writer tasks).
THREAD_POOL_NUM_WRITERS / _NUM_READERS	int	2 all	none	Dead, removed (pool depth is fixed in EsppTransport).
THREAD_POOL_WRITER_PRIO	int	5 / 3 / 3	none	Dead, removed.
THREAD_POOL_WORKLOAD_QUEUE_LENGTH_USERTRAFFIC / _METATRAFFIC	int	60 / 32 / 64	none	Dead, removed (EsppTransport sets max_queue_size = 64 itself).
OVERALL_HEAP_SIZE	constexpr int	derived	none	Dead, removed (summed only the dead stack constants).

Knob plumbing checks that passed: every Kconfig range fits the C++ type of the profile it applies to (uint8 knobs 0..255, uint16 0..65535, the two uint16-on-host registries 65535 only off embedded, seconds 0..3600 into int32, priorities 0..24, DOMAIN_ID 0..232); lib/espp.cmake applies the same per-type maxima; no exposed knob has a legitimate value of 0 that the 0 = profile default sentinel could shadow (DOMAIN_ID is always defined, so domain 0 works; priority 0 is the idle task; a 0 lease/period/cycle count is never sensible).

Fixes in 17ddebc

• Removed the nine dead constants above from all three profiles (and IP_ADDRESS plus its only reader, the uncalled 2-arg Participant::reuse).
• Added a "Tasks" preface in each profile explaining that the engine runs exactly two kinds of task, so readers stop looking for heartbeat/writer task knobs.
• VENDOR_ID / BASE_GUID_PREFIX comments (wire identity; esp32 fallback semantics); THREAD_POOL_READER_PRIO comment now names the real menu.
• ParticipantProxyData::isAlive() lease-to-ms arithmetic widened (see table).

Verification

• Host lib (lib/, default host profile) + rtps_golden, rtps_locator_subnet, rtps_sedp_dedicated_locator, rtps_pubsub: all PASS. The only host warnings are the pre-existing -Winconsistent-missing-override ones in StatelessWriter.hpp/StatefulWriter.hpp (untouched).
• Host configure with RTPS_LIMIT_OVERRIDES="SPDP_MAX_NUM_LOCATORS=4;SPDP_RESEND_PERIOD_MS=500;DOMAIN_ID=3;SPDP_MAX_REMOTE_LEASE_DURATION_S=30;THREAD_POOL_READER_PRIO=7": accepted, each override echoed.
• esp32 components/rtps/example (IDF 6.1, component manager off) with CONFIG_RTPS_DOMAIN_ID=5, CONFIG_RTPS_SPDP_DEFAULT_REMOTE_LEASE_DURATION_S=20, CONFIG_RTPS_LIMIT_SPDP_MAX_NUM_LOCATORS=4, CONFIG_RTPS_LIMIT_SPDP_MAX_NUMBER_FOUND_PARTICIPANTS=24, CONFIG_RTPS_SPDP_WRITER_PRIO=6: builds; all five RTPS_CFG_* definitions reach the compiler (checked in compile_commands.json); no warnings from components/rtps.
• clang-format (pre-commit) clean on the touched files.

Open questions (not changed)

1. TopicData::readFromBuffer accepts a name of exactly MAX_*NAME_LENGTH bytes. Per CDR the length includes the NUL, so a conforming peer can never leave the array unterminated, but a non-conforming one could (and matchesTopicOf uses strcmp). Forcing name[len-1] = '\0' after readBytes would be a cheap hardening; left alone because it is not a config issue.
2. SPDP_CYCLECOUNT_HEARTBEAT=0 (liveliness check every announce round) is a legitimate value the 0 = profile default sentinel hides. Nobody is likely to want it, but if so the Kconfig would need a -1-style sentinel.
3. THREAD_POOL_READER_STACKSIZE is int while SPDP_WRITER_STACKSIZE is uint16_t; both have a 65535 ceiling in Kconfig/host validation, so it is cosmetic. Harmonising them (both uint16_t, or both int) would be a type change on a public header, so I left it for a separate decision.

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