持久化的 map ，使用 BerkeleyDB
使用前面介绍的序列化框架，可以非常简单地将Bekeley DB作为存储层，实现一个易于使用的，强类型的，持久化的map。
这个设计的的基本原则就是：模板作为一个薄的、类型安全的包装层，实现层的代码可以多个模板实例来公用，这样不但加快了编译时间，也减小了生成的代码尺寸。
这个实现相当于std::map<Key,Data>，但接口上也不完全相同，主要是基于易实现和性能考虑。
下一篇介绍std::map<Key1,std::map<Key2,Data> >的BerkeleyDB实现。
多的不说，贴上代码。
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#ifndef __febird_bdb_dbmap_h__ #define __febird_bdb_dbmap_h__ #if defined(_MSC_VER) && (_MSC_VER >= 1020) # pragma once #endif #include <db_cxx.h> #include "native_compare.hpp" #include "../io/DataIO.hpp" #include "../io/MemStream.hpp" #include "../util/refcount.hpp" #include <febird/num_to_str.hpp> #if DB_VERSION_MAJOR > 4 || (DB_VERSION_MAJOR == 4 && DB_VERSION_MINOR >= 6) #else #error BerkelyDB version too low, please update #endif namespace febird { class FEBIRD_DLL_EXPORT dbmap_iterator_impl_base : public RefCounter { public: class dbmap_base* m_owner; DBC* m_curp; int m_ret; public: dbmap_iterator_impl_base(class dbmap_base* owner); void init(DB* dbp, DB_TXN* txn, const char* func); virtual ~dbmap_iterator_impl_base(); virtual void load_key(void* data, size_t size) = 0; virtual void load_val(void* data, size_t size) = 0; virtual void save_key(PortableDataOutput<AutoGrownMemIO>& oKey) = 0; void advance(u_int32_t direction_flag, const char* func); void update(const void* d, const char* func); void remove(const char* func); }; class FEBIRD_DLL_EXPORT dbmap_base { DECLARE_NONE_COPYABLE_CLASS(dbmap_base) public: DB* m_db; size_t m_bulkSize; bt_compare_fcn_type m_bt_comp; dbmap_base(DB_ENV* env, const char* dbname , u_int32_t flags , DB_TXN* txn , bt_compare_fcn_type bt_comp , const char* func ); virtual ~dbmap_base(); virtual void save_key(PortableDataOutput<AutoGrownMemIO>& dio, const void* key) const = 0; virtual void save_val(PortableDataOutput<AutoGrownMemIO>& dio, const void* data) const = 0; virtual dbmap_iterator_impl_base* make_iter() = 0; dbmap_iterator_impl_base* begin_impl(DB_TXN* txn, const char* func); dbmap_iterator_impl_base* end_impl(DB_TXN* txn, const char* func); dbmap_iterator_impl_base* find_impl(const void* k, DB_TXN* txn, u_int32_t flags, const char* func); bool insert_impl(const void* k, const void* d, u_int32_t flags, DB_TXN* txn, const char* func); bool remove_impl(const void* k, DB_TXN* txn, const char* func); void clear_impl(DB_TXN* txn, const char* func); }; template<class Key, class Val, class Value, class Impl> class dbmap_iterator : public std::iterator<std::bidirectional_iterator_tag, Value, ptrdiff_t, const Value*, const Value&> { boost::intrusive_ptr<dbmap_iterator_impl_base> m_impl; void copy_on_write() { if (m_impl->get_refcount() > 1) { Impl* q = static_cast<Impl*>(m_impl.get()); Impl* p = new Impl(q->m_owner); q->m_ret = q->m_curp->dup(q->m_curp, &p->m_curp, DB_POSITION); FEBIRD_RT_assert(0 == q->m_ret, std::runtime_error); m_impl.reset(p); } } private: #ifdef _MSC_VER //# pragma warning(disable: 4661) // declaration but not definition //! MSVC will warning C4661 "declaration but not definition" void operator++(int) { assert(0); } void operator--(int) { assert(0); } #else //! disable, because clone iterator will cause very much time and resource void operator++(int);// { assert(0); } void operator--(int);// { assert(0); } #endif public: dbmap_iterator() {} explicit dbmap_iterator(dbmap_iterator_impl_base* impl) : m_impl(impl) { assert(impl); assert(dynamic_cast<Impl*>(impl)); } // bool exist() const { return DB_NOTFOUND != m_impl->m_ret && DB_KEYEMPTY != m_impl->m_ret; } bool exist() const { return 0 == m_impl->m_ret; } void update(const Val& val) { m_impl->update(&val, BOOST_CURRENT_FUNCTION); } void remove() { m_impl->remove(BOOST_CURRENT_FUNCTION); } dbmap_iterator& operator++() { assert(0 == m_impl->m_ret); copy_on_write(); m_impl->advance(DB_NEXT, BOOST_CURRENT_FUNCTION); return *this; } dbmap_iterator& operator--() { assert(0 == m_impl->m_ret); copy_on_write(); m_impl->advance(DB_PREV, BOOST_CURRENT_FUNCTION); return *this; } const Value& operator*() const { assert(0 == m_impl->m_ret); return static_cast<Impl*>(m_impl.get())->m_kv; } const Value* operator->() const { assert(0 == m_impl->m_ret); return &static_cast<Impl*>(m_impl.get())->m_kv; } Value& get_mutable() const { assert(0 == m_impl->m_ret); return static_cast<Impl*>(m_impl.get())->m_kv; } }; template<class Key, class Val> class dbmap : protected dbmap_base { DECLARE_NONE_COPYABLE_CLASS(dbmap) public: typedef Key key_type; typedef std::pair<Key, Val> value_type; protected: class dbmap_iterator_impl : public dbmap_iterator_impl_base { public: value_type m_kv; dbmap_iterator_impl(dbmap_base* owner) : dbmap_iterator_impl_base(owner) {} virtual void load_key(void* data, size_t size) { PortableDataInput<MemIO> iKey; iKey.set(data, size); iKey >> m_kv.first; FEBIRD_RT_assert(iKey.eof(), std::logic_error); } virtual void load_val(void* data, size_t size) { PortableDataInput<MinMemIO> iVal; iVal.set(data); iVal >> m_kv.second; FEBIRD_RT_assert(iVal.diff(data) == size, std::logic_error); } virtual void save_key(PortableDataOutput<AutoGrownMemIO>& oKey1) { oKey1 << m_kv.first; } }; //! overrides void save_key(PortableDataOutput<AutoGrownMemIO>& dio, const void* key) const { dio << *(const Key*)key; } void save_val(PortableDataOutput<AutoGrownMemIO>& dio, const void* val) const { dio << *(const Val*)val; } dbmap_iterator_impl_base* make_iter() { return new dbmap_iterator_impl(this); } public: typedef dbmap_iterator<Key, Val, value_type, dbmap_iterator_impl> iterator, const_iterator; //! constructor //! @param bt_comp //! Key 比较函数，默认情况下自动推导 //! -# 如果 Key 是预定义类型，会推导至相应的比较函数 //! -# 如果是自定义类型，会推导至 Key::bdb_bt_compare, 如果未定义此函数或原型不匹配，都会报错 //! -# 也可以直接指定，从而禁止自动推导 dbmap(DB_ENV* env, const char* dbname , u_int32_t flags = DB_CREATE , DB_TXN* txn = NULL , bt_compare_fcn_type bt_comp = bdb_auto_bt_compare((Key*)(0)) ) : dbmap_base(env, dbname, txn, bt_comp, BOOST_CURRENT_FUNCTION) { } dbmap(DbEnv* env, const char* dbname , u_int32_t flags = DB_CREATE , DbTxn* txn = NULL , bt_compare_fcn_type bt_comp = bdb_auto_bt_compare((Key*)(0)) ) : dbmap_base(env->get_DB_ENV(), dbname, flags, txn ? txn->get_DB_TXN() : NULL, bt_comp, BOOST_CURRENT_FUNCTION) { } iterator begin(DB_TXN* txn = NULL) { return iterator(begin_impl(txn, BOOST_CURRENT_FUNCTION)); } iterator end (DB_TXN* txn = NULL) { return iterator(end_impl (txn, BOOST_CURRENT_FUNCTION)); } iterator begin(DbTxn* txn) { return iterator(begin_impl(txn ? txn->get_DB_TXN() : NULL, BOOST_CURRENT_FUNCTION)); } iterator end (DbTxn* txn) { return iterator(end_impl (txn ? txn->get_DB_TXN() : NULL, BOOST_CURRENT_FUNCTION)); } value_type back() { iterator iter = this->end(); --iter; if (iter.exist()) return *iter; throw std::runtime_error(BOOST_CURRENT_FUNCTION); } value_type front() { iterator iter = this->begin(); if (iter.exist()) return *iter; throw std::runtime_error(BOOST_CURRENT_FUNCTION); } iterator find(const Key& k, DB_TXN* txn = NULL) { return iterator(find_impl(&k, txn, DB_SET, BOOST_CURRENT_FUNCTION)); } iterator find(const Key& k, DbTxn* txn) { return iterator(find_impl(&k, txn ? txn->get_DB_TXN() : NULL, DB_SET, BOOST_CURRENT_FUNCTION)); } iterator lower_bound(const Key& k, DB_TXN* txn = NULL) { return iterator(find_impl(&k, txn, DB_SET_RANGE, BOOST_CURRENT_FUNCTION)); } iterator lower_bound(const Key& k, DbTxn* txn) { return iterator(find_impl(&k, txn ? txn->get_DB_TXN() : NULL, DB_SET_RANGE, BOOST_CURRENT_FUNCTION)); } bool insert(const std::pair<Key,Val>& kv, DB_TXN* txn = NULL) { return insert_impl(&kv.first, &kv.second, DB_NOOVERWRITE, txn, BOOST_CURRENT_FUNCTION); } bool insert(const std::pair<Key,Val>& kv, DbTxn* txn) { return insert_impl(&kv.first, &kv.second, DB_NOOVERWRITE, txn ? txn->get_DB_TXN() : NULL, BOOST_CURRENT_FUNCTION); } bool insert(const Key& k, const Val& d, DB_TXN* txn = NULL) { return insert_impl(&k, &d, DB_NOOVERWRITE, txn, BOOST_CURRENT_FUNCTION); } bool insert(const Key& k, const Val& d, DbTxn* txn) { return insert_impl(&k, &d, DB_NOOVERWRITE, txn ? txn->get_DB_TXN() : NULL, BOOST_CURRENT_FUNCTION); } void replace(const std::pair<Key,Val>& kv, DB_TXN* txn = NULL) { insert_impl(&kv.first, &kv.second, 0, txn, BOOST_CURRENT_FUNCTION); } void replace(const std::pair<Key,Val>& kv, DbTxn* txn) { insert_impl(&kv.first, &kv.second, 0, txn ? txn->get_DB_TXN() : NULL, BOOST_CURRENT_FUNCTION); } void replace(const Key& k, const Val& d, DB_TXN* txn = NULL) { insert_impl(&k, &d, 0, txn, BOOST_CURRENT_FUNCTION); } void replace(const Key& k, const Val& d, DbTxn* txn) { insert_impl(&k, &d, 0, txn ? txn->get_DB_TXN() : NULL, BOOST_CURRENT_FUNCTION); } bool remove(const Key& k, DB_TXN* txn = NULL) { return remove_impl(&k, txn, BOOST_CURRENT_FUNCTION); } bool remove(const Key& k, DbTxn* txn) { return remove_impl(&k, txn ? txn->get_DB_TXN() : NULL, BOOST_CURRENT_FUNCTION); } bool erase(iterator& iter) { return iter.remove(); } void clear(DB_TXN* txn = NULL) { clear_impl(txn, BOOST_CURRENT_FUNCTION); } void clear(DbTxn* txn) { return clear_impl(txn ? txn->get_DB_TXN() : NULL, BOOST_CURRENT_FUNCTION); } DB* getDB() { return m_db; } const DB* getDB() const { return m_db; } }; } // namespace febird #endif // __febird_bdb_dbmap_h__ |
楼主贴源码怎么推广使用啊？ 应该贴如何调用的代码吧？