Gary

Performance Benchmark 

• Hash Table Benchmarks
• Hash Table Performance Tests
• Benchmarks: Std::tr1::unordered_map Vs Boost::unordered_map Vs Std::map

 

使用方法

• dense_hash_map的复杂key的用法
• C++: hashtable - Why won't this compile?
• Unordered Map With Custom Structures
• dense_hash_map<Key, Data, HashFcn, EqualKey, Alloc>
• unordered_map hash function c++

 

Hash Function

• MurmurHash
• MurmurHash PK CityHash
• Super high performance C/C++ hash map (table, dictionary)

 

Note

• Insert 前要呼叫 set_empty_key function
• Erase 前要呼叫 set_deleted_key function
• 若欲 Insert 的 key 為自訂型別，要提供 hash function 及 equal function
  
  

  class pairHashTri{
  public:
  	size_t operator()(const std::pair<std::pair<int,int>,int> &k) {
  		
  		return k.first.first * 100 + k.first.second * 10 + k.second;
  	}
  };
  
  struct eqstr
  {
  	bool operator()(CLMEntry &s1, CLMEntry &s2) const
  	{
  		return (s1.fBackoff == s2.fBackoff && s1.fProb == s2.fProb);
  	}
  };
  
  google::dense_hash_map<std::pair<std::pair<int,int>,int>, 
                                 CLMEntry, pairHashTri> mapTrigram;
  

 

 

google_hash.rar