小型RAM数据库

允许快速访问数据的RAM数据库。

如何安装

[dependencies]
tiny_ram_db = "0.1.0"

如何使用它

    extern crate tiny_ram_db;
    extern crate error_chain;
    use std::string::ToString;
    use std::thread;
    use std::time::Instant;
    use tiny_ram_db::{Index, Indexer, Record, Table, PlainTable};
    use tiny_ram_db::errors::*;

    struct Author {
        name: String,
    }

    impl Author {
        fn new<I: ToString>(name: I) -> Self {
            Self {
                name: name.to_string(),
            }
        }
    }

    struct Post {
        text: String,
        author: Record<Author>,
    }

    #[derive(Default)]
    struct PostIndexes {
        by_author: Index<Record<Author>, Post>,
        by_text: Index<String, Post>,
    }

    impl Indexer for PostIndexes {
        type Item = Post;
        fn index(&mut self, item: &Record<Post>) -> Result<bool> {
            self.by_author.insert(item.data.author.clone(), item.clone())?;
            self.by_text.insert(item.data.text.clone(), item.clone())?;
            Ok(true)
        }
    }

    impl Post {
        fn new<I: ToString>(author: &Record<Author>, text: I) -> Self {
            Self {
                author: author.clone(),
                text: text.to_string(),
            }
        }
    }

    #[derive(Clone)]
    struct Database {
        authors: PlainTable<Author>,
        posts: Table<Post, PostIndexes>,
    }

    fn create_db() -> Result<Database> {
        let mut db: Database = Database {
            authors: PlainTable::new(),
            posts: Table::new(),
        };

        let bob = db.authors.insert(Author::new("bob"))?;
        let ana = db.authors.insert(Author::new("ana"))?;

        let mut handles = vec![];

        let mut bob_db = db.clone();
        let bob_thread = thread::spawn(move || {
            for x in 0..500_000 {
                bob_db.posts.insert(
                    Post::new(&bob, format!("Bob says hello #{}", x)),
                ).unwrap();
            }
        });

        handles.push(bob_thread);

        let mut ana_db = db.clone();
        let ana_thread = thread::spawn(move || {
            for x in 0..500_000 {
                ana_db.posts.insert(
                    Post::new(&ana, format!("Ana says hello #{}", x)),
                ).unwrap();
            }
        });

        handles.push(ana_thread);

        for handle in handles {
            handle.join().expect("Error joining handles");
        }

        Ok(db)
    }

    fn obtain_data() {
        obtain_data_result().expect("Error")
    }

    fn obtain_data_result() -> Result<()> {
        let start = Instant::now();
        let db = create_db()?;
        println!("DB Creation took {:?}", start.elapsed());
        let a_post = db.posts.find(400000)?;
        println!("A post text is: {}", &a_post.data.text);
        println!("A post author is: {}", &a_post.data.author.data.name);
        let by_author = db.posts.indexes.read()?.by_author
            .get(&a_post.data.author, |items| items.len() )?;

        println!("Author total post count is : {}", by_author);

        let by_text = db.posts.indexes.read()?.by_text
            .get(&"Bob says hello #9".into(), |e|
            e.iter().nth(0).unwrap().clone()
            )?;

        println!("Bob post #9 author is {}", by_text.data.author.data.name);

        Ok(())
    }