[PATCH v2 0/4] test-tool: split up "read-cache" tool

A re-roll addressing the feedback v1 got, see https://lore.kernel.org/git/cover-0.4-0000000000-20210607T115454Z-avarab@gmail.com

I think the gist of that feedback from Emily was that v1 could be understood as aiming to optimize the perf test, but the main reason I'm doing this split up is to make the code easier to read. The changed commit message summarizes both goals.

I also changed some nits in the code I spotted myself, e.g. "argc > 0" checks to just "argc", and a simpler way of providing the "cnt" default.

Ævar Arnfjörð Bjarmason (4):
  test-tool: split up test-tool read-cache
  test-tool: migrate read-cache-perf to parse_options()
  test-tool: migrate read-cache-again to parse_options()
  read-cache perf: add a perf test for refresh_index()

 Makefile                         |  2 ++
 t/helper/test-read-cache-again.c | 45 +++++++++++++++++++++++++
 t/helper/test-read-cache-perf.c  | 47 +++++++++++++++++++++++++++
 t/helper/test-read-cache.c       | 56 +++++++++++++-------------------
 t/helper/test-tool.c             |  2 ++
 t/helper/test-tool.h             |  2 ++
 t/perf/p0002-read-cache.sh       |  7 +++-
 t/t7519-status-fsmonitor.sh      |  2 +-
 8 files changed, 128 insertions(+), 35 deletions(-)
 create mode 100644 t/helper/test-read-cache-again.c
 create mode 100644 t/helper/test-read-cache-perf.c

Range-diff against v1:
1:  6e7fcd46934 ! 1:  adb3f989a29 test-tool: split up test-tool read-cache
    @@ Commit message
         test-tool: split up test-tool read-cache
     
         Since the "test-tool read-cache" was originally added back in
    -    1ecb5ff141 (read-cache: add simple performance test, 2013-06-09) it's
    -    been growing all sorts of bells and whistles that aren't very
    -    conducive to performance testing the index, e.g. it learned how to
    -    read config.
    +    1ecb5ff141 (read-cache: add simple performance test, 2013-06-09) the
    +    test-read-cache.c tool has been growing various features that make the
    +    code harder to read. I.e. sometimes running as a one-off, sometimes looping.
    +
    +    It's also been unconditionally reading config since
    +    dc76852df2f (fsmonitor: demonstrate that it is not refreshed after
    +    discard_index(), 2019-05-07), which introduces unnecessary noise into
    +    the performance test.
     
         Then in recent changes in e2df6c3972 (test-read-cache: print cache
         entries with --table, 2021-03-30) and 2782db3eed (test-tool: don't
    @@ Commit message
     
         I think that having one test tool do so many different things makes it
         harder to read its code. Let's instead split up the "again" and "perf"
    -    uses for it into their own tools.
    +    uses for it into their own small tools, this makes the main
    +    "test-read-cache.c" a simpler.
     
         Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
     
    @@ t/helper/test-read-cache.c: static void print_cache(struct index_state *istate)
     +	};
     +
     +	argc = parse_options(argc, argv, "test-tools", options, read_cache_usage, 0);
    -+	if (argc > 0)
    ++	if (argc)
     +		usage_msg_opt("Too many arguments.", read_cache_usage, options);
      
      	initialize_the_repository();
2:  07f392e0878 ! 2:  a68fa4a6355 test-tools: migrate read-cache-perf to parse_options()
    @@ Metadata
     Author: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
     
      ## Commit message ##
    -    test-tools: migrate read-cache-perf to parse_options()
    +    test-tool: migrate read-cache-perf to parse_options()
     
         Change the newly added (but then mostly copy/pasted) read-cache-perf
         to use the parse_options() API. This will make things easier as we add
    @@ t/helper/test-read-cache-perf.c
     -		die("usage: test-tool read-cache-perf [<count>]");
     +	argc = parse_options(argc, argv, "test-tools", options,
     +			     read_cache_perf_usage, 0);
    -+	if (argc > 0)
    ++	if (argc)
     +		usage_msg_opt("Too many arguments.", read_cache_perf_usage,
     +			      options);
     +	if (cnt < 1)
3:  36f4072b131 ! 3:  a34e69eaa48 test-tools: migrate read-cache-again to parse_options()
    @@ Metadata
     Author: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
     
      ## Commit message ##
    -    test-tools: migrate read-cache-again to parse_options()
    +    test-tool: migrate read-cache-again to parse_options()
     
         Change the newly added (but then mostly copy/pasted) read-cache-perf
         to use the parse_options() API. I have no plans to further modify
    @@ t/helper/test-read-cache-again.c
      {
      	struct repository *r = the_repository;
     -	int i, cnt;
    -+	int cnt = -1;
    ++	int cnt = 2;
      	const char *name;
     +	struct option options[] = {
     +		OPT_INTEGER(0, "count", &cnt, "number of passes"),
    @@ t/helper/test-read-cache-again.c
     +	if (argc != 1)
     +		usage_msg_opt("Too many arguments.", read_cache_again_usage,
     +			      options);
    -+	if (cnt == -1)
    -+		cnt = 2;
    -+	else if (cnt < 1)
    ++	if (cnt < 1)
     +		usage_msg_opt("Need at least one pass.", read_cache_again_usage,
     +			      options);
      	name = argv[2];
4:  120a37acaef = 4:  e3648bf78c7 read-cache perf: add a perf test for refresh_index()