/tokenspeed-scheduler/tests/cpp/test_prefetch.cpp

// Copyright (c) 2026 LightSeek Foundation
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#include "integration_test_helper.h"

namespace tokenspeed::test {

class PrefetchTestSuite : public SchedulerTestSuite {
protected:
    SchedulerConfig MakeConfig() override {
        auto cfg = SchedulerTestSuite::MakeConfig();
        cfg.device_allocator.total_pages = 32;
        cfg.host_allocator.total_pages = 32;
        cfg.enable_l3_storage = true;
        cfg.prefetch_threshold = 2;
        return cfg;
    }

    static const PrefetchOperation* GetPrefetch(const ExecutionPlan& plan) {
        for (const auto& op : plan.Operations()) {
            if (auto* cop = std::get_if<CacheOperation>(&op)) {
                if (auto* pf = std::get_if<PrefetchOperation>(cop)) return pf;
            }
        }
        return nullptr;
    }

    static const FlatForwardOperation* GetForwardOp(const ExecutionPlan& plan) {
        for (const auto& op : plan.Operations()) {
            if (auto* f = std::get_if<FlatForwardOperation>(&op)) return f;
        }
        return nullptr;
    }
};

TEST_F(PrefetchTestSuite, Prefetch_GeneratedForL3StorageHit) {
    Submit(MakePrefetchableSpec("r1", /*num_pages=*/4, /*storage_hit_pages=*/3));
    auto plan = PlanOnce();

    const auto* pf = GetPrefetch(plan);
    // Prefetch may or may not be generated depending on the match state.
    // But request should at least be in forward.
    auto* fwd = GetForwardOp(plan);
    ASSERT_NE(fwd, nullptr);
    bool r1_found = false;
    for (const auto& rid : fwd->request_ids) {
        if (rid == "r1") r1_found = true;
    }
    // Request should either be prefetching (not in forward) or in forward.
    EXPECT_TRUE(r1_found || pf != nullptr);
}

TEST_F(PrefetchTestSuite, NoPrefetch_WhenL3Disabled) {
    auto cfg = MakeConfig();
    cfg.enable_l3_storage = false;
    scheduler_ = std::make_unique<Scheduler>(cfg);

    Submit(MakePrefetchableSpec("r1", 4, 3));
    auto plan = PlanOnce();
    const auto* pf = GetPrefetch(plan);
    EXPECT_EQ(pf, nullptr);
}

TEST_F(PrefetchTestSuite, NoPrefetch_BelowThreshold) {
    // storage_hit_pages=1 < prefetch_threshold=2
    Submit(MakePrefetchableSpec("r1", 4, 1));
    auto plan = PlanOnce();
    const auto* pf = GetPrefetch(plan);
    EXPECT_EQ(pf, nullptr);
}

}  // namespace tokenspeed::test