Reduce moc parse time by 60% with lightweight MAVLink headers#14241
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DonLakeFlyer merged 1 commit intomavlink:masterfrom Mar 30, 2026
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Reduce moc parse time by 60% with lightweight MAVLink headers#14241DonLakeFlyer merged 1 commit intomavlink:masterfrom
DonLakeFlyer merged 1 commit intomavlink:masterfrom
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…eight headers Replace MAVLinkLib.h (~180,000 preprocessed lines) with targeted lightweight headers in files that only need enums or base types: - MAVLinkEnums.h (build-generated): enum typedefs only (~5,200 lines) - MAVLinkMessageType.h: mavlink_message_t and base types (~2,700 lines) - QGCMAVLinkTypes.h: FirmwareClass_t, VehicleClass_t, maxRcChannels - VehicleTypes.h: MavCmdResultFailureCode_t, RequestMessageResultHandlerFailureCode_t Also replace Vehicle.h includes with forward declarations and VehicleTypes.h where only Vehicle enum types are needed in headers. Measured moc parse time across all 550 headers: Before: 458s total, 182 slow (>100ms), 367 fast (<20ms) After: 185s total, 71 slow (>100ms), 452 fast (<20ms) Total moc parse time reduced by 273 seconds (60%).
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Build ResultsPlatform Status
All builds passed. Pre-commit
Pre-commit hooks: 4 passed, 32 failed, 7 skipped. Test Resultslinux-sanitizers: 67 passed, 0 skipped Artifact Sizes
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Summary
Replace heavy
MAVLinkLib.h(~180,000 preprocessed lines) with targeted lightweight headers in files that only need enums or base types. This reduces total moc parse time across all 550 headers by 273 seconds (60%).Measured Results
Timing methodology: single-pass
moc --output-dep-file /dev/nullacross all 550.hfiles insrc/andtest/, using include paths fromcompile_commands.json.Approach
The root cause was
MAVLinkLib.hpulling in all 387 MAVLink message headers (~180k preprocessed lines) through every header that needed even a single MAVLink enum. Most headers only need enums (MAV_CMD,MAV_TYPE, etc.) or themavlink_message_tbase type — not the full message pack/unpack machinery.New lightweight headers
MAVLinkEnums.h(build-generated)MAVLinkMessageType.hmavlink_message_t,mavlink_channel_t, base typesQGCMAVLinkTypes.hFirmwareClass_t,VehicleClass_t,maxRcChannelsVehicleTypes.hMavCmdResultFailureCode_t,RequestMessageResultHandlerFailureCode_tHeader migration
MAVLinkLib.horQGCMAVLink.htoMAVLinkEnums.hand/orMAVLinkMessageType.hQGCMAVLink.htoQGCMAVLinkTypes.hVehicle.htoVehicleTypes.h+ forward declarationQGCMAVLink.hitself switched fromMAVLinkLib.htoMAVLinkEnums.h+MAVLinkMessageType.h(biggest single impact — 18 direct + 61 transitive includers)Build-generated
MAVLinkEnums.hcmake/GenerateMAVLinkEnums.pyextracts enum typedef sections from all 19 MAVLink dialect headers (text between// ENUM DEFINITIONSand// MESSAGE DEFINITIONSmarkers). The CMake custom command runs after the MAVLink CPM package is fetched and only regenerates when content changes.Backward compatibility
Vehicleinherits fromVehicleTypesandQGCMAVLinkinherits fromQGCMAVLinkTypes, so all existing code usingVehicle::MavCmdResultFailureCode_torQGCMAVLink::VehicleClass_tetc. continues to work unchanged. The PCH still includesMAVLinkLib.hfor.ccfile compilation.Remaining slow headers
The remaining 71 slow headers all trace back to 16 Tier 3 headers that still need
MAVLinkLib.hbecause they use specific message struct types (mavlink_command_long_t,mavlink_file_transfer_protocol_t, etc.) in their declarations. These could be addressed in a follow-up.