Perf(common): optimize cache promotion and demotion

[zztaki]

What problem does this PR solve?

Issue Number: #2946

Problem Summary: current cache promotion and demotion need to copy a duplica, erase old elem and reinsert duplica.

What is changed and how it works?

What's Changed: optimize cache promotion and demotion using list.splice and add some tests.

How it Works: list.splice will update cache object priority without object duplica, list reinsertion and hashtable update.

Side effects(Breaking backward compatibility? Performance regression?):

Check List

• Relevant documentation/comments is changed or added
• I acknowledge that all my contributions will be made under the project's license

[zztaki]

This is a performance test.

#include <benchmark/benchmark.h>
static void GetWithDuplicate(benchmark::State& state){
    auto cache = std::make_shared<LRUCache<int, int>>(5, nullptr);
    for (int i = 0; i < 5; i++) {
        cache->Put(i, i);
    }
    int v;
    for (auto _ : state) {
        for (int k = 0; k < 5; k++) {
            cache->Get(k, &v);
            assert(k == v);
        }
    }
}
BENCHMARK(GetWithDuplicate);

static void GetWithoutDuplicate(benchmark::State& state){
    auto cache = std::make_shared<LRUCache<int, int>>(5, nullptr);
    for (int i = 0; i < 5; i++) {
        cache->Put(i, i);
    }
    int v;
    for (auto _ : state) {
        for (int k = 0; k < 5; k++) {
            cache->GetWithSplice(k, &v);
            assert(k == v);
        }
    }
}
BENCHMARK(GetWithoutDuplicate);

BENCHMARK_MAIN();

Result is

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[zztaki]

@Ziy1-Tan Hello, this is my first encounter with CI. In fact, I've added some relevant tests that should completely cover my modifications. But CI tells me coverage ratio 72.9 < expectd 73. I don’t know if this is because my modifications are not up to standard or if it’s due to other modules. I hope I can get your help. :)

[zztaki]

Maybe I can add some tests for arc_cache.

[Ziy1-Tan]

Maybe I can add some tests for arc_cache.

Nice, try to add some unit tests. Maybe LRUCache is included by many places, so it trigged code coverage check at these files that had not checked before.

[zztaki]

Maybe I can add some tests for arc_cache.

Nice, try to add some unit tests. Maybe LRUCache is included by many places, so it trigged code coverage check at these files that had not checked before.

Thanks~

[Ziy1-Tan]

Why delete these lines?

[Ziy1-Tan]

This function also include some metrics code, maybe you should consider it?

[zztaki]

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[zztaki]

Since the line coverage and branch coverage of the existing src/client are not up to standard, an additional commit which adds some tests was submitted.

[zztaki]

close #2982