关于leveldb

下载leveldb源码

链接: leveldbGit地址

增加测试文件

使用clion打开项目，在根目录下新建一个app目录，app目录下新建一个main.cpp。代码如下：

//
//
#include <cassert>
#include <iostream>
#include "include/leveldb/db.h"


int main() {
  //std::cout << "leveldb open success!" << std::endl;
  //return 0;

  leveldb::DB *db;
  leveldb::Options options;
  options.create_if_missing = true;
  leveldb::Status status = leveldb::DB::Open(options, "c://myLevelDB", &db);
  assert(status.ok());
  std::cout << "leveldb open success!" << std::endl;
  std::string value;
  std::string key1 = "testkey1";
  leveldb::Status s = db->Get(leveldb::ReadOptions(), key1, &value);
  if (s.IsNotFound()) {
    std::cout << "can not found for key:" << key1 << std::endl;
    db->Put(leveldb::WriteOptions(), key1, "testvalue1");
  }
  s = db->Get(leveldb::ReadOptions(), key1, &value);
  if (s.ok()) {
    std::cout << "found key:" << key1 << ",value:" << value << std::endl;
  }
  s = db->Delete(leveldb::WriteOptions(), key1);
  if (s.ok()) {
    std::cout << "delete key success which key:" << key1 << std::endl;
  }
  s = db->Get(leveldb::ReadOptions(), key1, &value);
  if (s.IsNotFound()) {
    std::cout << "can not found after delete for key:" << key1 << std::endl;
  }
  delete db;
  return 0;
}

更新cmake文件

在CMakeList.txt里面寻找leveldbutil字符串，然后在下面增加

add_executable(myTest "app/main.cpp")
target_link_libraries(myTest leveldb)

最终效果如下：

运行

关于RocksDB

下载RocksDB代码

同上，在根目录的app目录下增加测试文件main.cpp,代码如下：

//
// Created by  on 2024/1/11.
//
#include <iostream>
#include <string>

#include "rocksdb/db.h"
#include "rocksdb/options.h"
#include "rocksdb/slice.h"

using ROCKSDB_NAMESPACE::DB;
using ROCKSDB_NAMESPACE::Options;
using ROCKSDB_NAMESPACE::PinnableSlice;
using ROCKSDB_NAMESPACE::ReadOptions;
using ROCKSDB_NAMESPACE::Status;
using ROCKSDB_NAMESPACE::WriteBatch;
using ROCKSDB_NAMESPACE::WriteOptions;

// rocksdb存储路径
std::string kDBPath="c://myrocksdb";

int main()
{
  DB* db;
  Options options;
  options.IncreaseParallelism();
  //文件夹没有数据就创建
  options.create_if_missing=true;
  // 打开数据库，加载数据到内存
  Status s=DB::Open(options,kDBPath,&db);
  assert(s.ok());
  // 写key-value
  s=db->Put(WriteOptions(),"key01","value");
  assert(s.ok());

  std::string value;
  s=db->Get(ReadOptions(),"key01",&value);
  assert(s.ok());
  std::cout<<"get value  "<< value<<std::endl;
  assert(value=="value");
  // 管道，原子方式更新
  {
    WriteBatch batch;
    batch.Delete("key01");
    batch.Put("key02",value);
    s=db->Write(WriteOptions(),&batch);
  }
  s=db->Get(ReadOptions(),"key01",&value);
  assert(s.IsNotFound());
  s=db->Get(ReadOptions(),"key02",&value);
  assert(value=="value");

  {
    PinnableSlice pinnable_val;
    // 列族方式读取
    db->Get(ReadOptions(),db->DefaultColumnFamily(),"key02",&pinnable_val);
    assert(pinnable_val=="value");
  }

  {
    std::string string_val;
    PinnableSlice pinnable_val(&string_val);
    // 列族方式读取
    db->Get(ReadOptions(),db->DefaultColumnFamily(),"key02",&pinnable_val);
    assert(pinnable_val=="value");
    assert(pinnable_val.IsPinned() || string_val == "value");
  }

  PinnableSlice pinnable_val;
  s=db->Get(ReadOptions(),db->DefaultColumnFamily(),"key01",&pinnable_val);
    assert(s.IsNotFound());

    pinnable_val.Reset();
    db->Get(ReadOptions(),db->DefaultColumnFamily(),"key02",&pinnable_val);
    assert(pinnable_val=="value");
    pinnable_val.Reset();

    delete db;

    return 0;
}

修改CMakelist.txt

增加如下内容：

add_executable(myTest "app/main.cpp")
target_link_libraries(myTest ${ROCKSDB_STATIC_LIB})

效果如下：

运行

参考资料：

https://zhuanlan.zhihu.com/p/653465714
https://zhuanlan.zhihu.com/p/611450548