Michał Górny <mgo...@gentoo.org> writes:
> On Mon, 2023-07-31 at 12:41 +0200, Florian Schmaus wrote:
>> With 59dbfb80f748 ("cargo.eclass: Add variable alternative to
>> $(cargo_crate_uris)") the _cargo_set_crate_uris function was
>> introduced. This function runs when the elcass is inherited and sets
>> CARGO_CRATE_URIS.
>>
>> Ebuilds that use $(cargo_crate_uris) in SRC_URI will again invoke this
>> function, even though CARGO_CRATE_URIS is already set. Avoiding this
>> unnecessary computation reduces the ebuild source time of
>> app-shells/nushell-0.83.0 from 21 ms to 14 ms.
>>
>> This is a significant reduction when compared to the variable-setting
>> alternative that the commit 59dbfb80f748 ("cargo.eclass: Add variable
>> alternative to $(cargo_crate_uris)") introduced. Using the
>> variable-setting approach would reduce the ebuild source time only by a
>> little bit more than one millisecond.
>>
>> Using
>>
>> pk pkg source --bench 10s '=app-shells/nushell-0.83.0'
>>
>> as benchmark, yields
>>
>> > | Cached CARGO_CRATE_URIS | Non-Cached
>> > CARGO_CRATE_URIS |
>> > ---------------------------+-------------------------+-----------------------------|
>> > $(cargo_crate_uris) | mean: 14.189ms | mean: 21.445ms
>> > |
>> > variable-setting approach | mean: 12.822ms | mean: 12.852ms
>> > |
>>
>> full benchmark output
>>
>> > | Cached CARGO_CRATE_URIS (this commit)
>> > | Non-Cached CARGO_CRATE_URIS
>> > |
>> > ---------------------------+------------------------------------------------------------------+------------------------------------------------------------------|
>> > $(cargo_crate_uris) | mean: 14.189ms, min: 13.646ms, max: 15.103ms,
>> > σ = 149µs, N = 705 | mean: 21.445ms, min: 20.79ms, max: 22.832ms, σ =
>> > 228µs, N = 467 |
>> > variable-setting approach | mean: 12.822ms, min: 12.41ms, max: 13.909ms,
>> > σ = 165µs, N = 780 | mean: 12.852ms, min: 12.367ms, max: 15.437ms, σ =
>> > 227µs, N = 779 |
>>
>> Signed-off-by: Florian Schmaus <f...@gentoo.org>
>> ---
>> eclass/cargo.eclass | 8 ++++++++
>> 1 file changed, 8 insertions(+)
>>
>> diff --git a/eclass/cargo.eclass b/eclass/cargo.eclass
>> index 70b6008d9cd8..5d6911801097 100644
>> --- a/eclass/cargo.eclass
>> +++ b/eclass/cargo.eclass
>> @@ -240,6 +240,14 @@ _cargo_set_crate_uris "${CRATES}"
>> # Constructs a list of crates from its arguments.
>> # If no arguments are provided, it uses the CRATES variable.
>> cargo_crate_uris() {
>> + # Use already existing value for CARGO_CRATE_URIS, computed by
>> + # _cargo_set_crate_uris, when this function is invoked without
>> + # arguments.
>> + if [[ $# -eq 0 && -n "${CARGO_CRATE_URIS}" ]]; then
>> + echo "${CARGO_CRATE_URIS}"
>> + return
>> + fi
>> +
>> local crates=${*-${CRATES}}
>> if [[ -z ${crates} ]]; then
>> eerror "CRATES variable is not defined and nothing passed as
>> argument"
>
> This incorrectly assumes that the value of CRATES did not change which
> isn't guaranteed anywhere.
Ah, thanks! Now I remember - we discussed it before and rejected it for
this reason.
