eis/inc/zlib/MemMap.hpp

/************************************************
 * Fixed element pointer position.
 * The current pointer points to the latest element
 * by means of a primary key value
 *
 * create zoufuzhou 20201001
 * modify zoufuzhou 20251024  Initializable key memory
 *
 ************************************************/
#ifndef _MEM_MAP_CACHE_HPP_
#define _MEM_MAP_CACHE_HPP_
#include <glob/GlobMem.h>
#include <mutex>
#include <tuple>
#include <typeinfo>

const short KEY_LEN = 48;
// TValue requires a fixed length structure
template <typename TKey, typename TValue> class CMemMap {
  typedef struct {
    unsigned int maxsize;
    unsigned int size;
    unsigned int next;
  } HEAD;
  typedef struct {
    char key[KEY_LEN];
    TValue value;
  } SM_DAT;

private:
  std::tuple<string, unsigned int> mt_lastkey;

private:
  HEAD *p_head;
  SM_DAT *p_ptr;

private:
  std::mutex m_mutex;

private:
  // std::string toString(const TKey &key) {
  //   std::ostringstream ostream;
  //   ostream.unsetf(std::ios::skipws);
  //   ostream << key;
  //   if (typeid(TKey) == typeid(string)) {
  //     return ostream.str();
  //   }
  //   std::istringstream istream(ostream.str());
  //   std::string value;
  //   istream >> value;
  //   return value;
  // }
  std::string toString(const TKey &key) const {
    return toStringImpl(key, std::is_same<TKey, std::string>());
  }

  void init(const string &tableName) {
    char *ptr = (char *)GlobMem::GetInstancePtr()->GetTablePtr(tableName);
    if (ptr == nullptr) {
      p_ptr = nullptr;
      p_head = nullptr;
      return;
    }
    p_head = (HEAD *)(ptr);
    p_ptr = (SM_DAT *)(ptr + sizeof(HEAD));
  };

public:
  // size does not need to be map get
  CMemMap(const string &tableName) {
    this->init(tableName);
    // assert(p_head->maxsize>1);
  };

  // map insert need set cache maxsize
  CMemMap(const string &tableName, unsigned int maxsize) {
    // assert(maxsize>1);
    this->init(tableName);

    p_head->maxsize = maxsize;
    if (p_head->size > p_head->maxsize) {
      p_head->size = p_head->maxsize;
    }

    m_mutex.lock();
    if (p_head->next > p_head->maxsize) {
      p_head->next = p_head->maxsize;
    }
    p_head->next = p_head->next % p_head->maxsize;
    m_mutex.unlock();
  };

  ~CMemMap(){};

  TValue *operator()(void) { return &p_ptr->value; };

  TValue *getCur(void) { return &(p_ptr + this->index_cur())->value; };

  long index_cur(void) {
    if (p_head->next <= 0) {
      return p_head->maxsize - 1;
    } else {
      return (p_head->next - 1) % p_head->maxsize;
    }
  }

  TValue *operator()(unsigned int i) {
    if (p_ptr == nullptr)
      return nullptr;
    return &(p_ptr + i)->value;
  };

  string getKey(unsigned int i) {
    if (p_ptr == nullptr)
      return nullptr;
    return (p_ptr + i)->key;
  };

  bool find(const TKey &tkey) {
    string key = this->toString(tkey);
    if (key == "")
      return nullptr;
    if (p_ptr == nullptr)
      return nullptr;

    if (std::get<0>(this->mt_lastkey) == key) {
      return &(p_ptr + std::get<1>(this->mt_lastkey))->value;
    }

    for (unsigned int i = 0; i < this->size(); i++) {
      if (memcmp((p_ptr + i)->key, key.c_str(), key.length()) == 0 &&
          key.length() < KEY_LEN && strlen((p_ptr + i)->key) == key.length()) {
        this->mt_lastkey = std::make_tuple(key, i);
        return true;
      }
    }
    return false;
  };

  TValue *operator[](const TKey &tkey) {
    string key = this->toString(tkey);
    if (key == "")
      return nullptr;
    if (p_ptr == nullptr)
      return nullptr;

    if (std::get<0>(this->mt_lastkey) == key) {
      return &(p_ptr + std::get<1>(this->mt_lastkey))->value;
    }

    for (unsigned int i = 0; i < this->size(); i++) {
      if (memcmp((p_ptr + i)->key, key.c_str(), key.length()) == 0 &&
          key.length() < KEY_LEN && strlen((p_ptr + i)->key) == key.length()) {
        this->mt_lastkey = std::make_tuple(key, i);
        return &(p_ptr + i)->value;
      }
    }
    return nullptr;
  };

  void insert(const TKey &tkey, TValue *tvalue) {
    string key = this->toString(tkey);
    if (key == "")
      return;
    if (p_ptr == nullptr)
      return;

    m_mutex.lock();
    TValue *tmp = this->operator[](tkey);
    if (tmp != nullptr) {
      memcpy(tmp, tvalue, sizeof(TValue));
    } else {
      if (p_head->size < p_head->maxsize) {
        p_head->size++;
      }

      this->mt_lastkey = std::make_tuple(key, p_head->next);
      memcpy(&(p_ptr + p_head->next)->value, tvalue, sizeof(TValue));
      memset(&(p_ptr + p_head->next)->key, 0, sizeof(p_ptr->key));
      int len = min(key.length(), sizeof(p_ptr->key));
      memcpy(&(p_ptr + p_head->next)->key, key.c_str(), len);
      p_head->next = (p_head->next + 1) % p_head->maxsize;
    }
    m_mutex.unlock();
  };

  bool empty(void) {
    if (p_head == nullptr)
      return 0;
    return !p_head->size;
  };

  unsigned int size(void) {
    if (p_head == nullptr)
      return 0;
    return p_head->size;
  };

  void clear(void) {
    if (p_head == nullptr)
      return;
    p_head->size = 0;
    p_head->next = 0;
  };

private:
  // 通用实现
  std::string toStringImpl(const TKey &key, std::false_type) const {
    std::ostringstream oss;
    oss << key;
    return oss.str();
  }

  // string特化实现
  std::string toStringImpl(const std::string &key, std::true_type) const {
    return key;
  }
};

#endif