Change rocksDB merging code

tools/rocksDB_merger/rocksDB_merger.cc

-/*
- *	Author : Ashwin <ashwin2007ray@gmail.com>
- *
- *	compile : g++ rocks_merge.cc <path_to_rocksDB_installation>/librocksdb.so.4.1 --std=c++11 -lstdc++fs
- *	usage : ./<executable> <folder_having_rocksDB_directories_to_be_merged> <destinatnion_folder>
- *
- */
-
-#include <fstream>
-#include <cstdio>
-#include <iostream>
-#include <string>
-
-#include "rocksdb/db.h"
-#include "rocksdb/slice.h"
-#include "rocksdb/options.h"
-
-#include <experimental/filesystem>
-
-using namespace rocksdb;
-namespace fs = std::experimental::filesystem;
-
-int main(int argc, char* argv[]) {
-	if(argc != 3) {
-		std::cerr << "Wrong number of arguments\nusage : ./<executable> <folder_having_rocksDB_directories_to_be_merged> <destinatnion_folder>\n";
-		return 1;
-	}
-	std::string kDBPath = argv[2];
-	DB* db;
-  	Options options;
-    	// Optimize RocksDB. This is the easiest way to get RocksDB to perform well
-    	options.IncreaseParallelism();
-    	options.OptimizeLevelStyleCompaction();
-    	// create the DB if it's not already present
-	options.create_if_missing = true;
-             
-    	// open DB
- 	Status s = DB::Open(options, kDBPath, &db);
-  	assert(s.ok());
-
-	for (auto& dirEntry : fs::directory_iterator(argv[1])) {
-		std::cout << dirEntry << "\n" ;
-	
-   	   	DB* cur_db;
-		Options options;
-    		options.IncreaseParallelism();
-    		options.OptimizeLevelStyleCompaction();
-    		// Don't create the DB if it's not already present
-		options.create_if_missing = false;
-             
-    		// open DB
- 		Status s1 = DB::Open(options, dirEntry.path().c_str(), &cur_db);
-  		assert(s1.ok());
-	
-		rocksdb::Iterator* it = cur_db->NewIterator(rocksdb::ReadOptions());
-	    	for (it->SeekToFirst(); it->Valid(); it->Next()) {
-			std::cout << it->key().ToString() << ": " << it->value().ToString() << std::endl;
-			s = db->Put(WriteOptions(), it->key().ToString(), it->value().ToString());
-			assert(s.ok());
-		}
-	    	assert(it->status().ok()); // Check for any errors found during the scan
-	  	delete it;
-		delete cur_db;
-	}
-/*
-	rocksdb::Iterator* it = db->NewIterator(rocksdb::ReadOptions());	
-	for (it->SeekToFirst(); it->Valid(); it->Next()) {
-	         std::cout << it->key().ToString() << ": " << it->value().ToString() << std::endl;
-	}
-	assert(it->status().ok()); // Check for any errors found during the scan
-	delete it;
-*/
-	delete db;	
-	return 0;
-}