cache.cpp

在n维空间（每维范围为0-1）内对插入的数值根据坐标进行分区。从一个没有分区的空间开始插入

#include "Cache.h"

extern int qtree_level;
extern Cache cache_memory;
extern filename[];
extern BlockFile myblockfile;

CacheBlock::CacheBlock(){
                           
    num_pts = 0;                   
    block_id = "";
	cache = new char[BLOCKLENGTH];      
                        
    write_ptr = cache + sizeof(int);   //write pointer always points to data, not to header
                       
}

CacheBlock::~CacheBlock(){
                         
  delete[] cache;
}

bool CacheBlock::write_one_data (Entry* data){
     int i= DIMENSION * sizeof(float); 
     
     if ((write_ptr + i) > (cache + BLOCKLENGTH)) return false;   //cacheblock full 
     
     // cacheblock not full
     num_pts++;
     memcpy(cache, &num_pts, sizeof(int));       //update number of points               
 
     for (int j=0; j<DIMENSION; j++) 
        {
         memcpy(write_ptr, &(data->data[j]), sizeof(float));    // write one data in cache
         write_ptr += sizeof(float);     //move write pointer
         }
     
     return true;
}

bool CacheBlock::read_whole_block (Entry** dataArray){
     
     int num=0;
     memcpy(&num, cache, sizeof(int));
     
     char* temp_ptr=cache + sizeof(int);  // pointer for reading
     
     for (int i=0;i<num ;i++)
       {
         for (int j=0; j<DIMENSION; j++)
         {
          memcpy(&(dataArray[i]->data[j]) ,temp_ptr, sizeof(float));         
          temp_ptr += sizeof(float);
         }
       }     
          
     return true;

}


//------------------------------------------------------------------------------------


Cache::Cache() {
	int i;

	cache_cont = new string[CACHESIZE];

	for (i = 0; i < CACHESIZE; i++) {
    	cache_cont[i] = "";
	}

	cacheblock = new CacheBlock[CACHESIZE];
	
//	for (i=0; i<cachesize;i++)
//	  cacheblock[i](blocklength);


}

Cache::~Cache() {
	delete[] cache_cont;
	delete[] cacheblock;
}

/*

bool Cache::write_block(Block block, string block_id) {
	    int c_ind;
    	c_ind = in_cache(block_id);
    	if(c_ind >= 0)  // in cache, overwrite it
			memcpy(cache[c_ind], block, blocklength);
        else    // not in cache, so it's a new block , allocate new space for it in the cache
            {   c_ind=find_available_space();
                if (c_ind<0) {cout<<"Cache full!"<<endl; //need to write some block to file, to be improved
                              return false;}
                else
                    {cache_cont[c_ind]= block_id;
		         	memcpy(cache[c_ind], block, blocklength);                
                    }                 
             }
        
        return true;
        
}
*/

int Cache::in_cache(string b_id) {
   int ret_val = -1;
   for (int i = 0; i < CACHESIZE; i++){
	   if (cache_cont[i] == b_id)  {
		   {ret_val = i; break;}
	   }
//	          cout<<cache_cont[i]<<"!="<<b_id<<"!"<<endl;

   }
   return ret_val;
}


int Cache::find_available_space(){
   int ret_val = -1; 
   for (int i = 0; i < CACHESIZE; i++)
       if (cache_cont[i]=="")    
            {ret_val = i; break;}
   return ret_val; 
}