Rust 編程中使用 leveldb 的簡單例子

前言

最近準備用Rust寫一個完善的blockchain的教學demo，在持久化時考慮到使用leveldb。通過查閱文檔，發現Rust中已經提供了使用leveldb的接口。將官方的例子修改了下，能夠運行通過。

示例

• 源碼

<code> 
use
 std::{env, fs};
use
 leveldb::database::Database;
use
 leveldb::iterator::Iterable;
use
 leveldb::kv::KV;
use
 leveldb::options::{Options,WriteOptions,ReadOptions};

fn
 
main
() {
  
let
 
mut
 dir = env::current_dir().unwrap();
  dir.push(
"demo"
);

  
let
 path_buf = dir.clone();
  fs::create_dir_all(dir).unwrap();

  
let
 path = path_buf.as_path();
  
let
 
mut
 options = Options::new();
  options.create_if_missing = 
true
;

　 
  
let
 database = 
match
 Database::open(path, options) {
      
Ok
(db) => { db },
      
Err
(e) => { 
panic!
(
"failed to open database: {:?}"
, e) }
  };

   
  
let
 write_opts = WriteOptions::new();
  
match
 database.put(write_opts, 
1
, &[
1
]) {
      
Ok
(_) => { () },
      
Err
(e) => { 
panic!
(
"failed to write to database: {:?}"
, e) }
  };

  
  
let
 read_opts = ReadOptions::new();
  
let
 res = database.get(read_opts, 
1
);

  
match
 res {
    
Ok
(data) => {
      
assert!
(data.is_some());
      
assert_eq!
(data, 
Some
(
vec!
[
1
]));
    }
    
Err
(e) => { 
panic!
(
"failed reading data: {:?}"
, e) }
  }

  
let
 read_opts = ReadOptions::new();
  
let
 
mut
 iter = database.iter(read_opts);
  
let
 entry = iter.next();
  
assert_eq!
(
    entry,
    
Some
((
1
, 
vec!
[
1
]))
  );
}/<code>

• 配置文件

<code> 
[ ]
leveldb = 
"0.8.5"
/<code>

關鍵字: read use options