RocksDB源码-0x04-Open流程

1 调试代码

int main() {
  rocksdb::Options options;
  options.create_if_missing = true;

  // 不在options中显式制定wal的目录就会用db_path
  std::string dbName = "/tmp/rocksdb_ctest_put";
  std::string walDir = dbName + "/wal";
  std::string sstDir = dbName + "/sst";
  options.wal_dir = walDir;
  std::vector<rocksdb::DbPath> sstPaths = {{sstDir + "/flash_path", 512},
                                           {sstDir + "/hard_drive", 1024}};
  options.db_paths = sstPaths;

  // sst目录属于资源目录 RocksDB不会帮我创建 要自己创建好
  auto* env = rocksdb::Env::Default();
  env->CreateDirIfMissing(dbName);
  env->CreateDirIfMissing(walDir);
  env->CreateDirIfMissing(sstDir);
  env->CreateDirIfMissing(sstDir + "/flash_path");
  env->CreateDirIfMissing(sstDir + "/hard_drive");

  std::unique_ptr<rocksdb::DB> db;
  auto s = rocksdb::DB::Open(options, dbName, &db);
  assert(s.ok());

  for (int i = 0; i < 10; ++i) {
    s = db->Put(rocksdb::WriteOptions(), "hello" + std::to_string(i),
                "world" + std::to_string(i));
  }
  std::string value;
  // get value
  s = db->Get(rocksdb::ReadOptions(), "hello", &value);

  db->Flush(rocksdb::FlushOptions());

  return 0;
}

2 安装必要的工具用来解析文件

直接在主机上安装rocksdb，在解析文件的时候要用到这些自带的工具

1
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3

brew install rocksdb

ls $(brew --prefix rocksdb)/bin

3 启动前准备重要的目录文件

上面代码运行完会生成下面的这些文件

➜  rocksdb_ctest_put tree
.
├── CURRENT
├── IDENTITY
├── LOCK
├── LOG
├── MANIFEST-000005
├── OPTIONS-000007
├── sst
│   ├── flash_path
│   │   └── 000009.sst
│   └── hard_drive
└── wal
    └── 000008.log