justSpender.sol

pragma solidity ^0.4.24;

contract Sample {

  uint[] values;
  
  function justGasSpendingTx(uint gasToSpend) public  {
  
    uint gasLeftAtStart = gasleft();
   
    require(gasToSpend > 21000);
    uint gasLeftToSpend = gasToSpend - 21000; 
    
    if(gasLeftToSpend > 20000){
        
        uint length = uint(gasLeftToSpend)/uint(20000);
   
        values.length = length;
    
        for (uint index=0;index< values.length;index++)
        {
           values[index] = index; //Gas 20000 to set a value; BIG TICKET ITEM
        }
    } 
    
    int remaining = int(gasLeftToSpend - (gasLeftAtStart - gasleft()));
    if(remaining < 700) {
        return;
    }
    
    uint codeSizeBlockRunCount = (uint(remaining)/uint(700));
    
    for(index=0; index < codeSizeBlockRunCount ;index ++){ 
        //  Gas for extcodesize is 700. BIG TICKET ITEM
        uint32 size;     
        address thisAddress =this ;
        
        assembly {
             size := extcodesize(thisAddress)
        }
        
     }
    //  and other big ticket items LogX, Call, Contract creation etc can be used
  
 }

  
 function getGasLimitAndGasLeft() public view returns (uint, uint) {
     
    return (block.gaslimit, gasleft());
    
  }
 
 
}