apache / httpd - Conditional Complexity

Intro

Conditional complexity (also called cyclomatic complexity) is a term used to measure the complexity of software. The term refers to the number of possible paths through a program function. A higher value ofter means higher maintenance and testing costs (infosecinstitute.com).
Conditional complexity is calculated by counting all conditions in the program that can affect the execution path (e.g. if statement, loops, switches, and/or operators, try and catch blocks...).
Conditional complexity is measured at the unit level (methods, functions...).
Units are classified in four categories based on the measured McCabe index: 1-5 (simple units), 6-10 (medium complex units), 11-25 (complex units), 26+ (very complex units).

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Conditional Complexity Overall

There are 4,105 units with 122,849 lines of code in units (52.9% of code).

45 very complex units (13,208 lines of code)
127 complex units (17,572 lines of code)
512 medium complex units (34,488 lines of code)
638 simple units (22,238 lines of code)
2,783 very simple units (35,343 lines of code)

Legend:

51+

26-50

11-25

6-10

1-5

Alternative Visuals

3D view of all units

Conditional Complexity per Extension

51+

26-50

11-25

6-10

1-5

Conditional Complexity per Logical Component

primary logical decomposition

51+

26-50

11-25

6-10

1-5

Most Complex Units

Top 50 most complex units

Unit	# lines	McCabe index	# params
static int proxy_ftp_handler() in modules/proxy/mod_proxy_ftp.c	706	177	6
int main() in support/htcacheclean.c	397	141	2
static int status_handler() in modules/generators/mod_status.c	728	117	1
static int fcomp() in modules/filters/sed0.c	418	116	2
int main() in support/ab.c	469	115	2
int ap_proxy_http_process_response() in modules/proxy/mod_proxy_http.c	515	113	1
static int parse_expr() in modules/filters/mod_include.c	356	108	3
static int ssl_hook_Access_classic() in modules/ssl/ssl_engine_kernel.c	319	97	5
static int APR_THREAD_FUNC regfnServerSupportFunction() in modules/arch/win32/mod_isapi.c	399	96	5
static void output_directories() in modules/generators/mod_autoindex.c	371	96	8
static apr_status_t command() in modules/filters/sed1.c	260	90	3
static int ap_proxy_ajp_request() in modules/proxy/mod_proxy_ajp.c	425	85	8
static int balancer_process_balancer_worker() in modules/proxy/mod_proxy_balancer.c	250	82	5
static apr_status_t deflate_out_filter() in modules/filters/mod_deflate.c	321	81	2
static apr_status_t send_parsed_content() in modules/filters/mod_include.c	291	73	2
static apr_status_t ajp_marshal_into_msgb() in modules/proxy/ajp_header.c	237	72	4
static int process_dir() in support/htcacheclean.c	291	71	3
static int index_directory() in modules/generators/mod_autoindex.c	215	69	2
int main() in support/suexec.c	270	69	2
static int proxy_handler() in modules/proxy/mod_proxy.c	234	68	1
static int dav_method_copymove() in modules/dav/main/mod_dav.c	266	68	2
static void pstartElement() in modules/filters/mod_proxy_html.c	295	67	3
apr_status_t ap_h1_body_in_filter() in modules/http/http_filters.c	202	65	5
static apr_status_t dispatch() in modules/proxy/mod_proxy_fcgi.c	320	64	9
int main() in support/win32/wintty.c	249	64	2
static int _advance() in modules/filters/regexp.c	175	63	3
static int dav_method_options() in modules/dav/main/mod_dav.c	219	63	1
static int imap_handler_internal() in modules/mappers/mod_imagemap.c	224	63	1
static apr_status_t ssl_io_filter_handshake() in modules/ssl/ssl_engine_io.c	271	62	1
static apr_status_t deflate_in_filter() in modules/filters/mod_deflate.c	307	62	5
static int authenticate_digest_user() in modules/aaa/mod_auth_digest.c	196	61	1
static int hook_uri2file() in modules/mappers/mod_rewrite.c	219	59	1
static int hook_fixup() in modules/mappers/mod_rewrite.c	215	59	1
static apr_status_t proxy_send_dir_filter() in modules/proxy/mod_proxy_ftp.c	244	58	2
static int find_ct() in modules/http/mod_mime.c	201	57	1
int main() in server/main.c	278	57	2
static void balancer_display_page() in modules/proxy/mod_proxy_balancer.c	450	56	5
static int alias_match_servlet() in modules/proxy/mod_proxy.c	144	56	3
static apr_status_t compress_filter() in modules/filters/mod_brotli.c	171	55	2
static int proxy_http_handler() in modules/proxy/mod_proxy_http.c	173	54	6
static int apply_rewrite_cond() in modules/mappers/mod_rewrite.c	142	54	3
static apr_status_t ap_fgetline_core() in server/protocol.c	197	53	7
apr_status_t h2_session_process() in modules/http2/h2_session.c	215	52	3
static void set_neg_headers() in modules/mappers/mod_negotiation.c	130	51	3
static int prefork_run() in server/mpm/prefork/prefork.c	233	51	3
static apr_status_t acme_renew() in modules/md/md_acme_drive.c	215	50	2
static void output_results() in support/ab.c	254	50	1
static void read_response() in support/ab.c	194	50	1
static int do_headers_fixup() in modules/metadata/mod_headers.c	131	49	4
static apr_ssize_t send_response_header() in modules/arch/win32/mod_isapi.c	123	49	5