// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you under the Apache License, Version 2.0 (the

// "License"); you may not use this file except in compliance

// with the License.  You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing,

// software distributed under the License is distributed on an

// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, either express or implied.  See the License for the

// specific language governing permissions and limitations

// under the License.

#pragma once

#include <butil/macros.h>

#include <glog/logging.h>

#include <stddef.h>

#include <stdint.h>

#include <atomic>

#include <map>

#include <memory>

#include <mutex>

#include <roaring/roaring.hh>

#include <string>

#include <unordered_map>

#include <vector>

#include "common/config.h"

#include "common/status.h"

#include "core/block/block.h"

#include "io/fs/file_system.h"

#include "io/fs/path.h"

#include "runtime/exec_env.h"

#include "runtime/memory/lru_cache_policy.h"

#include "runtime/memory/mem_tracker.h"

#include "util/lru_cache.h"

#include "util/slice.h"

#include "util/time.h"

namespace doris {

class BaseTablet;

struct TabletReadSource;

using CacheResult = std::vector<BlockUPtr>;

// A handle for mid-result from query lru cache.

// The handle will automatically release the cache entry when it is destroyed.

// So the caller need to make sure the handle is valid in lifecycle.

class QueryCacheHandle {

public:

    QueryCacheHandle() = default;

    QueryCacheHandle(LRUCachePolicy* cache, Cache::Handle* handle)

            : _cache(cache), _handle(handle) {}

    ~QueryCacheHandle() {

        if (_handle != nullptr) {

            CHECK(_cache != nullptr);

            {

                SCOPED_SWITCH_THREAD_MEM_TRACKER_LIMITER(

                        ExecEnv::GetInstance()->query_cache_mem_tracker());

                _cache->release(_handle);

            }

        }

    }

    QueryCacheHandle(QueryCacheHandle&& other) noexcept {

        std::swap(_cache, other._cache);

        std::swap(_handle, other._handle);

    }

    QueryCacheHandle& operator=(QueryCacheHandle&& other) noexcept {

        std::swap(_cache, other._cache);

        std::swap(_handle, other._handle);

        return *this;

    }

    bool valid() const { return _handle != nullptr; }

    std::vector<int>* get_cache_slot_orders();

    CacheResult* get_cache_result();

    int64_t get_cache_version();

    // How many incremental merges have been accumulated on this entry since the

    // last full recompute. See QueryCacheRuntime for the compaction policy.

    int64_t get_cache_delta_count();

    int64_t get_cache_total_bytes();

    int64_t get_cache_total_rows();

private:

    LRUCachePolicy* _cache = nullptr;

    Cache::Handle* _handle = nullptr;

    // Don't allow copy and assign

    DISALLOW_COPY_AND_ASSIGN(QueryCacheHandle);

};

class QueryCache : public LRUCachePolicy {

public:

    using LRUCachePolicy::insert;

    struct CacheValue : public LRUCacheValueBase {

        int64_t version;

        CacheResult result;

        std::vector<int> slot_orders;

        // Number of incremental merges accumulated on this entry since the last

        // full recompute. 0 means the entry was produced by a full scan.

        int64_t delta_count;

        // Size of this entry, used to decide upfront whether an incremental

        // merge could ever be written back under the entry_max_bytes/rows

        // limits (a merged entry can only be larger than the cached one).

        int64_t total_bytes;

        int64_t total_rows;

        CacheValue(int64_t v, CacheResult&& r, const std::vector<int>& so, int64_t dc = 0,

                   int64_t bytes = 0)

                : LRUCacheValueBase(),

                  version(v),

                  result(std::move(r)),

                  slot_orders(so),

                  delta_count(dc),

                  total_bytes(bytes) {

            total_rows = 0;

            for (const auto& block : result) {

                total_rows += block->rows();

            }

        }

    };

    // Create global instance of this class

    static QueryCache* create_global_cache(size_t capacity, uint32_t num_shards = 16) {

        auto* res = new QueryCache(capacity, num_shards);

        return res;

    }

    static Status build_cache_key(const std::vector<TScanRangeParams>& scan_ranges,

                                  const TQueryCacheParam& cache_param, std::string* cache_key,

                                  int64_t* version) {

        if (scan_ranges.empty()) {

            return Status::InternalError("scan_ranges is empty, plan error");

        }

        std::string digest;

        try {

            digest = cache_param.digest;

        } catch (const std::exception&) {

            return Status::InternalError("digest is invalid, plan error");

        }

        if (digest.empty()) {

            return Status::InternalError("digest is empty, plan error");

        }

        if (cache_param.tablet_to_range.empty()) {

            return Status::InternalError("tablet_to_range is empty, plan error");

        }

        std::vector<int64_t> tablet_ids;

        tablet_ids.reserve(scan_ranges.size());

        for (const auto& scan_range : scan_ranges) {

            auto tablet_id = scan_range.scan_range.palo_scan_range.tablet_id;

            tablet_ids.push_back(tablet_id);

        }

        std::sort(tablet_ids.begin(), tablet_ids.end());

        int64_t first_version = -1;

        std::string first_tablet_range;

        for (size_t i = 0; i < tablet_ids.size(); ++i) {

            auto tablet_id = tablet_ids[i];

            auto find_tablet = cache_param.tablet_to_range.find(tablet_id);

            if (find_tablet == cache_param.tablet_to_range.end()) {

                return Status::InternalError("Not find tablet in partition_to_tablets, plan error");

            }

            auto scan_range_iter =

                    std::find_if(scan_ranges.begin(), scan_ranges.end(),

                                 [&tablet_id](const TScanRangeParams& range) {

                                     return range.scan_range.palo_scan_range.tablet_id == tablet_id;

                                 });

            int64_t current_version = -1;

            std::from_chars(scan_range_iter->scan_range.palo_scan_range.version.data(),

                            scan_range_iter->scan_range.palo_scan_range.version.data() +

                                    scan_range_iter->scan_range.palo_scan_range.version.size(),

                            current_version);

            if (i == 0) {

                first_version = current_version;

                first_tablet_range = find_tablet->second;

            } else {

                if (current_version != first_version) {

                    return Status::InternalError(

                            "All tablets in one instance must have the same version, plan error");

                }

                if (find_tablet->second != first_tablet_range) {

                    return Status::InternalError(

                            "All tablets in one instance must have the same tablet_to_range, plan "

                            "error");

                }

            }

        }

        *version = first_version;

        *cache_key = digest;

        for (auto tablet_id : tablet_ids) {

            *cache_key += std::string(reinterpret_cast<char*>(&tablet_id), sizeof(tablet_id));

        }

        *cache_key += first_tablet_range;

        return Status::OK();

    }

    // Return global instance.

    // Client should call create_global_cache before.

    static QueryCache* instance() { return ExecEnv::GetInstance()->get_query_cache(); }

    QueryCache() = delete;

    QueryCache(size_t capacity, uint32_t num_shards)

            : LRUCachePolicy(CachePolicy::CacheType::QUERY_CACHE, capacity, LRUCacheType::SIZE,

                             3600 * 24, /*num_shards*/ num_shards,

                             /*element_count_capacity*/ 0, /*enable_prune*/ true,

                             /*is_lru_k*/ true) {}

    // Ensure Block memory freed during eviction is tracked under query cache, not Orphan.

    int64_t adjust_capacity_weighted(double adjust_weighted) override {

        SCOPED_SWITCH_THREAD_MEM_TRACKER_LIMITER(ExecEnv::GetInstance()->query_cache_mem_tracker());

        return LRUCachePolicy::adjust_capacity_weighted(adjust_weighted);

    }

    int64_t reset_initial_capacity(double adjust_weighted) override {

        SCOPED_SWITCH_THREAD_MEM_TRACKER_LIMITER(ExecEnv::GetInstance()->query_cache_mem_tracker());

        return LRUCachePolicy::reset_initial_capacity(adjust_weighted);

    }

    void prune_stale() override {

        SCOPED_SWITCH_THREAD_MEM_TRACKER_LIMITER(ExecEnv::GetInstance()->query_cache_mem_tracker());

        LRUCachePolicy::prune_stale();

    }

    bool lookup(const CacheKey& key, int64_t version, QueryCacheHandle* handle);

    // Look up the entry by key regardless of its version. The caller decides

    // whether the entry is an exact hit (cached version == expected version) or

    // a stale entry usable for incremental merge. Returns false if the key is

    // not in the cache at all.

    bool lookup_any_version(const CacheKey& key, QueryCacheHandle* handle);

    void insert(const CacheKey& key, int64_t version, CacheResult& result,

                const std::vector<int>& solt_orders, int64_t cache_size, int64_t delta_count = 0);

};

// The per-fragment-instance decision of how the query cache participates in the

// execution, made exactly once (see QueryCacheRuntime) and consumed by both the

// olap scan operator and the cache source operator, so the two operators can

// never disagree (e.g. scan skips scanning because the entry looked fresh while

// cache source misses because the entry got evicted in between -- which would

// silently produce an empty result and poison the cache with it).

struct QueryCacheInstanceDecision {

    enum class Mode {

        // Run the full scan and (if the key is valid) write the result back.

        MISS,

        // The cached entry matches the current version: emit cached blocks,

        // skip scanning entirely, do not write back.

        HIT,

        // A stale entry is reusable: scan only the delta rowsets in

        // (cached_version, current_version], emit the cached blocks and the

        // delta partial result side by side (the upstream merge aggregation

        // combines them), then write the merged entry back.

        INCREMENTAL,

    };

    ~QueryCacheInstanceDecision();

    // Take the pre-captured delta read source of one tablet. Returns nullptr if

    // absent (already taken or never captured). Only meaningful in INCREMENTAL

    // mode; each tablet's read source can be consumed exactly once.

    std::unique_ptr<TabletReadSource> take_delta_read_source(int64_t tablet_id);

    Mode mode = Mode::MISS;

    // False when build_cache_key failed (e.g. tablets in this instance carry

    // different versions because FE could not align instances to partitions).

    // In that case the query degrades to an uncached scan: no lookup, no write

    // back, but the query itself still succeeds.

    bool key_valid = false;

    // False when the merged entry could never satisfy entry_max_bytes/rows

    // because the reused cached entry alone already exceeds them: the query

    // still scans only the delta (INCREMENTAL), but skips cloning blocks for a

    // write back that would be discarded anyway.

    bool write_back_feasible = true;

    // Why a stale entry was not reused incrementally (empty when it was, or

    // when incremental merge is not enabled for this query). For the query

    // profile only.

    std::string incremental_fallback_reason;

    std::string cache_key;

    // The version this query is reading (from the scan ranges).

    int64_t current_version = 0;

    // Only set in INCREMENTAL mode: the version of the reused stale entry.

    int64_t cached_version = 0;

    // Only set in HIT/INCREMENTAL mode: delta merges accumulated on the entry.

    int64_t cached_delta_count = 0;

    // Pins the cache entry in HIT/INCREMENTAL mode so it cannot be evicted (and

    // its blocks cannot be freed) while this query is using it. Note the pin

    // lives until the fragment is torn down; when the merged entry replaces

    // this one under the same key, both stay in memory for that window and the

    // LRU usage accounting only sees the new one (the mem tracker still sees

    // both) -- bounded by (in-flight incremental queries) x entry size.

    QueryCacheHandle handle;

private:

    friend class QueryCacheRuntime;

    std::mutex _take_lock;

    // INCREMENTAL mode: read sources of (cached_version, current_version]

    // captured at decision time, keyed by tablet id. Captured eagerly so that a

    // capture failure (e.g. the delta versions were merged away by compaction)

    // downgrades the decision to MISS *before* any operator acts on it; if the

    // scan discovered the failure only at prepare time, the cache source might

    // already have decided to emit the stale blocks.

    std::unordered_map<int64_t, std::unique_ptr<TabletReadSource>> _delta_read_sources;

};

// Fragment-level query cache context shared by the olap scan operator and the

// cache source operator of the same fragment. Both operators obtain the cache

// decision of their instance through get_or_make_decision(); the first caller

// makes the decision and the other one observes the same object, whatever the

// operator local-state init order is.

class QueryCacheRuntime {

public:

    // `cache` is injectable for tests; production callers pass nullptr and the

    // global instance is used.

    explicit QueryCacheRuntime(const TQueryCacheParam& param, QueryCache* cache = nullptr)

            : _param(param), _cache(cache != nullptr ? cache : QueryCache::instance()) {}

    QueryCache* cache() const { return _cache; }

    // Row-binlog scans read a different data stream and must not serve or fill

    // the query cache. Called while building the operator tree (single

    // threaded, before any local state init), so no locking is needed.

    void disable_for_binlog_scan() { _binlog_scan = true; }

    // Idempotent: the first call for a given instance (identified by the cache

    // key derived from its scan ranges) makes the decision, later calls return

    // the same decision object. Never returns nullptr.

    std::shared_ptr<QueryCacheInstanceDecision> get_or_make_decision(

            const std::vector<TScanRangeParams>& scan_ranges);

#ifdef BE_TEST

    // Tests inject a hand-crafted decision (e.g. INCREMENTAL) for an instance,

    // since a real storage engine is unavailable to capture delta read sources.

    void inject_decision_for_test(const std::string& cache_key,

                                  std::shared_ptr<QueryCacheInstanceDecision> decision) {

        std::lock_guard<std::mutex> lock(_lock);

        _decisions[cache_key] = std::move(decision);

    }

#endif

private:

    void _make_decision(const std::vector<TScanRangeParams>& scan_ranges,

                        QueryCacheInstanceDecision* decision);

    // Try to turn a stale entry into an INCREMENTAL decision. Returns true on

    // success; on any failure the caller keeps the decision as MISS (full

    // recompute), which is always safe.

    bool _try_prepare_incremental(const std::vector<TScanRangeParams>& scan_ranges,

                                  QueryCacheInstanceDecision* decision);

    // Validate one tablet for incremental merge and capture its delta read

    // source of (cached_version, current_version]. On any failure records the

    // fallback reason in the decision and returns false.

    bool _capture_tablet_delta(int64_t tablet_id, int64_t cached_version,

                               QueryCacheInstanceDecision* decision);

    // Merge-on-write only: true if any delete-bitmap entry stamped with a

    // version inside (cached_version, current_version] targets a rowset

    // OUTSIDE the captured delta set, i.e. the delta window rewrote rows that

    // are already folded into the cached partial result (an upsert, a partial

    // update or a delete sign hit a key that predates the cached version).

    // Entries targeting the delta rowsets themselves are harmless: the delta

    // scan reads those rowsets with the delete bitmap applied.

    static bool _delta_rewrites_history(BaseTablet& tablet, const TabletReadSource& delta_source,

                                        int64_t cached_version, int64_t current_version);

    TQueryCacheParam _param;

    QueryCache* _cache = nullptr;

    bool _binlog_scan = false;

    std::mutex _lock;

    std::map<std::string, std::shared_ptr<QueryCacheInstanceDecision>> _decisions;

    // Shared by every instance whose cache key cannot be built (see

    // get_or_make_decision): one immutable MISS decision, one log line.

    std::shared_ptr<QueryCacheInstanceDecision> _invalid_decision;

};

} // namespace doris