[tor-bugs] #15236 [Tor]: Identify functions most in need of testing, and hardest to test

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#15236: Identify functions most in need of testing, and hardest to test
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     Reporter:  nickm   |      Owner:
         Type:  task    |     Status:  new
     Priority:  normal  |  Milestone:  Tor: 0.2.7.x-final
    Component:  Tor     |    Version:
   Resolution:          |   Keywords:  SponsorS
Actual Points:          |  Parent ID:
       Points:          |
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Comment (by nickm):

 I have a script that looks for functions with certain properties using
 `git-blame`.  It can count:
   * Lines
   * Number of distinct months of commits
   * Number of distinct commits
   * Number of distinct commits with the string "bug" in them

 Get the branch `findvolatile` from my public repository and play around
 with it.  It's a bit addictive.  Edit the 'badness' function.  Sort the
 results on different columns. Omit the "scariness" calculation if you
 aren't using it; it's slow!

 I pregenerated some git-blame output with `touch blame_all; for fn in
 src/common/*.c src/or/*.c src/tools/*.c src/tools/*/*.c ; do echo $fn;;
 git blame -wMC $fn >> blame_all; done`, and I've been piping it to lots of
 variants of this.

 So far, the different ways to calculate are pretty samey, and give similar
 results.  Big functions appear extra-high on the list. But there are ones
 that are "bad for their size" that get ranked a little higher than others.

 Top-10 longest functions (all lists by ascending badness):
 {{{
 circuit_expire_building
 parse_port_config
 run_scheduled_events
 connection_ap_handshake_rewrite_and_attach
 options_act
 networkstatus_parse_vote_from_string
 connection_dir_client_reached_eof
 directory_handle_command_get
 networkstatus_compute_consensus
 options_validate
 }}}

 Top-10 most scary functions (commits plus "bug" in log messages):
 {{{
 networkstatus_compute_consensus
 init_keys
 connection_edge_process_relay_cell
 connection_ap_handshake_rewrite_and_attach
 router_rebuild_descriptor
 directory_handle_command_get
 connection_dir_client_reached_eof
 run_scheduled_events
 options_act
 options_validate
 }}}

 Top 10 most modified functions (number of distinct commits):
 {{{
 circuit_expire_building
 parse_port_config
 run_scheduled_events
 connection_ap_handshake_rewrite_and_attach
 options_act
 networkstatus_parse_vote_from_string
 connection_dir_client_reached_eof
 directory_handle_command_get
 networkstatus_compute_consensus
 options_validate
 }}}

 Top 10 most high-scoring functions (sqrt(scariness times distinct months)
 divided by lines.):
 {{{
 router_dump_router_to_string
 connection_dir_client_reached_eof
 router_add_to_routerlist
 init_keys
 connection_exit_begin_conn
 connection_handle_write_impl
 router_rebuild_descriptor
 options_validate
 options_act
 run_scheduled_events
 }}}

 And now for something completely different: as above, but somewhat de-
 weighted for length:
 {{{
 consider_testing_reachability
 connection_connect_sockaddr
 connection_close_immediate
 add_callback_log
 tor_free_all
 router_rebuild_descriptor
 add_stream_log_impl
 run_scheduled_events
 connection_edge_destroy
 directory_info_has_arrived
 }}}

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/15236#comment:1>
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