fix: thread-safety bugs and cleanup from code review#6
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March 10, 2026 14:50
EdgeNode and HostApplication move constructors were reading members in the initializer list before locking other.mutex_ in the body — a data race if the source is accessed concurrently. Move all member transfers into the body under the lock. Also adds missing node_states_ transfer in HostApplication and primary_host_online_ in EdgeNode.
get_node_state() returned a reference_wrapper into mutex-protected map data; get_metric_name() returned a string_view. Both were readable after the lock was released, racing with MQTT callback mutations. get_node_state() now returns a lightweight NodeStateSnapshot (scalars only). get_metric_name() returns std::string. Callers that need alias resolution use get_metric_name() separately.
publish_state_birth/death held mutex_ while publish_raw_message blocked on a 5s future. If the Paho callback thread needed mutex_ to deliver on_message_arrived before firing the send-success callback, deadlock. Copy topic/payload/qos under the lock, release, then publish — matching the pattern EdgeNode already uses.
- Use SEQ_NUMBER_MAX constant consistently instead of literal 256 - Remove dead death_payload_data_ update in rebirth() (connect() overwrites it) - Remove unreachable timestamp fallback in PayloadBuilder::build() - Remove unused includes (memory, thread, algorithm, vector) - Document fire-and-forget QoS 0 semantics on command publish methods - Fix missing newlines at end of files
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Summary
Fixes from the 2026-03-10 code review. The first four are concurrency/correctness bugs, the rest are cleanup.
other.mutex_before reading members in the initializer listget_node_state()returns a lightweightNodeStateSnapshotby value;get_metric_name()returnsstd::stringpublish_state_birth/publish_state_death"online" : trueinstead of requiring exact"online":truerebirth()death payload,PayloadBuilder::build()timestamp fallback)SEQ_NUMBER_MAXconstant consistentlyTest plan
test_move_constructor_race— concurrent move with reader thread contentiontest_mutex_escaping_refs— snapshot/string ownership survives map mutationtest_state_publish_deadlock— STATE publish under message floodtest_state_json_parsing— 10 whitespace variations of STATE JSON