• There are 624 files with units, with 88,051 lines of code.
• 3 very complex files (McCabe index sum 251+; 5,282 lines of code)
• 19 complex files (McCabe index sum 126-250; 18,547 lines of code)
• 32 medium complex files (McCabe index sum 51-125; 12,460 lines of code)
• 73 slightly complex files (McCabe index sum 26-50; 17,363 lines of code)
• 497 simple files (McCabe index sum 1-25; 34,399 lines of code)
• 290 main files have no units (e.g. languages without unit analysis, or files without functions) and are not classified.

The McCabe index of a file grows with its size: per 100 lines tells a large but plain file from a dense one, and most complex unit whether the complexity sits in one unit or is spread over many.

File	# lines	# units	McCabe index (sum)	per 100 lines	most complex unit
FuseOps.cc in src/fuse	2255	62	450	20	48
ArgParse.h in src/common/utils	1231	63	258	21	35
RobinHood.h in src/common/utils	1796	125	256	14	11
StorageClientImpl.cc in src/client/storage	2075	52	233	11	18
Utf8.h in src/common/utils	1083	20	230	21	67
RapidCsv.h in src/common/utils	953	69	222	23	23
hf3fs_expected.h in src/lib/api	1366	99	218	16	18
MagicEnum.hpp in src/common/utils	1453	55	214	15	17
UnorderedDense.h in src/common/utils	1129	95	210	19	13
IBSocket.cc in src/common/net/ib	1073	52	204	19	14
Serde.h in src/common/serde	884	62	190	21	53
MgmtdClient.cc in src/client/mgmtd	855	75	174	20	12
Linenoise.c in src/common/utils	836	38	170	20	15
ConfigBase.h in src/common/utils	771	54	161	21	14
UsrbIo.cc in src/lib/api	671	26	160	24	18
GcManager.cc in src/meta/components	787	25	153	19	19
StorageOperator.cc in src/storage/service	1016	22	153	15	32
Nameof.hpp in src/common/utils	960	36	144	15	49
BatchOperation.cc in src/meta/store/ops	641	16	138	22	19
ChunkMetaStore.cc in src/storage/store	894	32	137	15	17
TypeTraits.h in src/common/utils	247	2	133	54	130
MetaClient.cc in src/client/meta	853	45	127	15	19
StorageBench.h in benchmarks/storage_bench	726	18	117	16	24
IBDevice.cc in src/common/net/ib	728	25	115	16	22
Utils.h in src/fbs/meta	401	28	110	27	27
data_placement.py in deploy/data_placement/src/model	449	35	109	24	19
IBConnect.cc in src/common/net/ib	646	19	99	15	16
TargetMap.cc in src/storage/service	370	22	90	24	39
ChunkReplica.cc in src/storage/store	390	6	78	20	41
FuseClients.cc in src/fuse	375	6	75	20	36
Transport.cc in src/common/net	320	15	73	23	14
StorageTarget.cc in src/storage/store	400	13	71	18	14
MemTransaction.h in src/common/kv/mem	336	17	71	21	26
RDMABuf.h in src/common/net/ib	356	45	70	20	4
Serde.cc in src/common/serde	358	37	70	20	4
__init__.py in hf3fs	242	30	64	26	9
ResyncWorker.cc in src/storage/sync	409	5	63	15	42
SetAttr.h in src/meta/store/ops	142	5	62	44	44
Common.h in src/fbs/meta	222	44	62	28	7
MetaOperator.cc in src/meta/service	384	31	61	16	6
Common.h in src/fbs/storage	665	37	60	9	8
IBSocket.h in src/common/net/ib	467	45	58	12	8
Rename.cc in src/meta/store/ops	279	8	57	20	22
PathResolve.cc in src/meta/store	286	12	55	19	13
Open.cc in src/meta/store/ops	253	11	55	22	19
Service.h in src/fbs/meta	636	29	55	9	7
StorageClient.h in src/client/storage	456	40	54	12	4
IoRing.cc in src/fuse	240	2	53	22	39
MgmtdMetricsUpdater.cc in src/mgmtd/background	251	15	52	21	11
Recorder.cc in src/common/monitor	290	19	52	18	9

• File complexity is the sum of the McCabe indexes (conditional complexity) of the units (methods, functions...) in a file.
• Files are classified in five categories based on that sum: 1-25 (simple files), 26-50 (slightly complex files), 51-125 (medium complex files), 126-250 (complex files), 251+ (very complex files). The default bands are five times the unit complexity bands, as a file is a group of units.
• Only main code files with units are classified. Files without units (languages without unit analysis, or files without functions) have no complexity to measure and are left out rather than counted as simple.
• A very complex file holds many decisions, which often means it has too many responsibilities: a candidate to split, and a place where changes need more testing.