/tokenspeed-scheduler/tests/cpp/test_outside_event_handler.cpp

// Copyright (c) 2026 LightSeek Foundation
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include "integration_test_helper.h"

namespace tokenspeed::test {

inline const FlatForwardOperation* GetForwardOp(const std::vector<Operation>& ops) {
    for (const auto& op : ops) {
        if (auto* f = std::get_if<FlatForwardOperation>(&op)) {
            return f;
        }
    }
    return nullptr;
}

inline std::int32_t FindRequestIndex(const FlatForwardOperation* fwd, const std::string& rid) {
    if (fwd == nullptr) return -1;
    for (std::size_t i = 0; i < fwd->request_ids.size(); ++i) {
        if (fwd->request_ids[i] == rid) return static_cast<std::int32_t>(i);
    }
    return -1;
}

class LoadBackDoneTestSuite : public SchedulerTestSuite {
protected:
    SchedulerConfig MakeConfig() override {
        auto cfg = SchedulerTestSuite::MakeConfig();
        cfg.decode_input_tokens = 0;
        cfg.device_allocator.total_pages = 5;
        cfg.host_allocator.total_pages = 32;
        cfg.enable_l3_storage = false;
        return cfg;
    }

    void SetupHostCache() {
        Submit(MakeRequestSpec("r1", /*num_pages=*/2, /*start=*/1));
        PlanOnce();
        SendForwardDone("r1", {42});
        PlanOnce();
        SendFinish("r1");
        auto plan_wb = PlanOnce();
        const FlatWriteBackOperation* wb = nullptr;
        for (const auto& op : plan_wb.Operations()) {
            if (auto* cop = std::get_if<CacheOperation>(&op)) {
                if (auto* w = std::get_if<FlatWriteBackOperation>(cop)) {
                    wb = w;
                    break;
                }
            }
        }
        ASSERT_NE(wb, nullptr) << "SetupHostCache: expected WriteBack op for r1";
        ASSERT_FALSE(wb->op_ids.empty());
        SendWriteBackDone(wb->op_ids[0]);
        PlanOnce();

        Submit(MakeRequestSpec("r_fill", /*num_pages=*/3, /*start=*/100));
        PlanOnce();
        SendForwardDone("r_fill", {200});
        PlanOnce();
        SendFinish("r_fill");
        auto plan_wb2 = PlanOnce();
        for (const auto& op : plan_wb2.Operations()) {
            if (auto* cop = std::get_if<CacheOperation>(&op)) {
                if (auto* w = std::get_if<FlatWriteBackOperation>(cop)) {
                    if (!w->op_ids.empty()) SendWriteBackDone(w->op_ids[0]);
                    break;
                }
            }
        }
        PlanOnce();
    }

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

// After host cache is populated, a new request with same tokens should see
// the host cache and be scheduled with reduced input_length (host pages already cached).
TEST_F(LoadBackDoneTestSuite, LoadBackDone_Success_PrefixLenChangesInForward) {
    SetupHostCache();

    Submit(MakeRequestSpec("r2", /*num_pages=*/2, /*start=*/1));
    auto plan = PlanOnce();
    auto* fwd = GetForwardOp(plan.Operations());
    ASSERT_NE(fwd, nullptr);
    auto idx = FindRequestIndex(fwd, "r2");
    ASSERT_GE(idx, 0) << "r2 should be in forward after host cache hit";

    // With block_size=2 and 4 prefill tokens, GetFullPagedTokens(except_last=true)
    // yields 3 tokens → 1 matchable page. Host has 2 pages but only 1 matches.
    // unscheduled = 4 - 1*2 = 2, so input_length = 2 and extend_prefix_len = 1*block_size = 2.
    EXPECT_EQ(fwd->input_lengths[idx], 2) << "host hit covers 1 page; 2 tokens remain";

    if (!fwd->extend_prefix_lens.empty()) {
        EXPECT_EQ(fwd->extend_prefix_lens[idx], 1 * PageSize()) << "extend_prefix_len should cover the 1 loadback page";
    }
}

// LoadBack is inline (synchronous); subsequent plans proceed normally.
TEST_F(LoadBackDoneTestSuite, LoadBack_SubsequentPlanProceeds) {
    SetupHostCache();

    Submit(MakeRequestSpec("r2", /*num_pages=*/2, /*start=*/1));
    auto plan = PlanOnce();

    auto plan2 = PlanOnce();
    (void)plan2;
    EXPECT_TRUE(true);
}

}  // namespace tokenspeed::test