What's the difference between add_benchmarks and add_benchmark?

Question

I am trying to migrate my pallet over to the parachain template, and while adding it to the runtime I noticed a slight difference between how benchmarks are defined.

On the old runtime, all (or most) pallets had their benchmarks included as follows:

    impl frame_benchmarking::Benchmark<Block> for Runtime {
        fn dispatch_benchmark(
            // <snip>
            add_benchmark!(params, batches, frame_system, SystemBench::<Runtime>);
            add_benchmark!(params, batches, pallet_balances, Balances);
            add_benchmark!(params, batches, pallet_timestamp, Timestamp);
            // Custom benchmark I want to migrate
            add_benchmark!(params, batches, pallet_chocolate, ChocolateModule);
            // <snip>

While the new one only has one call to a add_benchmarks macro.

    impl frame_benchmarking::Benchmark<Block> for Runtime {
        fn dispatch_benchmark(
            // <snip>
            add_benchmarks!(params, batches);
            // <snip>

I checked the docs and it suggests using the add_benchmark! but that was in the context of the node template. What's the difference between these two forms? Does add_benchmarks! have the same effect as the individual add_benchmark! calls combined??

Do note that I'm migrating from the node template runtime to the parachain template.

Many thanks!

Answer 1

Take a look at the PR which introduces this change:

https://github.com/paritytech/substrate/pull/10592

So the new syntax which is easier to maintain is:

define_benchmarks!(
    [path1, location1]
    ...
    [pathN, locationN]
);

impl_runtime_apis! {
    impl Benchmark<Block> for Runtime {
        fn benchmark_metadata(…)  {
            add_benchmarks!(list, extra);
        }

        fn dispatch_benchmark(…)  {
            list_benchmarks!(params, batches);
        }
    }
}

Where the define_benchmarks is combined with list_benchmarks and add_benchmarks.

This allows us to avoid having to have a huge list copied twice :)

End of the day, both syntax is supported, so you need not worry if you don't want to update.