When decoding reftable ref records we first release the pointer to the
record passed to us and then use realloc(3P) to allocate the refname
array. This is a bit misleading though as we know at that point that the
refname will always be `NULL`, so we would always end up allocating a
new char array anyway.
Refactor the code to use `REFTABLE_ALLOC_ARRAY()` instead. As the
following benchmark demonstrates this is a tiny bit more efficient. But
the bigger selling point really is the gained clarity.
Benchmark 1: show-ref: single matching ref (revision = HEAD~)
Time (mean ± σ): 150.1 ms ± 4.1 ms [User: 146.6 ms, System: 3.3 ms]
Range (min … max): 144.5 ms … 180.5 ms 1000 runs
Benchmark 2: show-ref: single matching ref (revision = HEAD)
Time (mean ± σ): 148.9 ms ± 4.5 ms [User: 145.2 ms, System: 3.4 ms]
Range (min … max): 143.0 ms … 185.4 ms 1000 runs
Summary
show-ref: single matching ref (revision = HEAD) ran
1.01 ± 0.04 times faster than show-ref: single matching ref (revision = HEAD~)
Ideally, we should try and reuse the memory of the old record instead of
first freeing and then immediately reallocating it. This requires some
more surgery though and is thus left for a future iteration.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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