Crate nut

Nut

Key-value embed database, which is basically port of Bolt DB

Examples

Create db and put something

use nut::DBBuilder;

let mut db = DBBuilder::new("test.db").build().unwrap();
let mut tx = db.begin_rw_tx().unwrap();
{
  let mut flowers = tx.create_bucket(b"flowers").unwrap();
  // returns mutable reference to bucket,
  // which prevents of reborrowing tx

  flowers.put(
    b"iris",
    b"song by American alternative rock band Goo Goo Dolls".to_vec()
  ).unwrap();
  flowers.put(
    b"binary data",
    vec![127, 127, 127, 127]
  ).unwrap();

  {
    // you can create subbuckets as well
    let mut annuals = flowers
      .create_bucket_if_not_exists(b"annuals").unwrap();

    // api is basically same as for transaction
    annuals.put(
      b"corn",
      b"American nu metal band from Bakersfield".to_vec()
    ).unwrap();
    // releasing subbucket
  }

  // releasing bucket to be able use tx again
}
// due to RAII tx will be automatically closed if no error occured,
// or rolled back if there was some.
// Additionally you can commit or rollback manually
tx.rollback().unwrap();

Getting data back

use nut::DBBuilder;

let mut db = DBBuilder::new("test.db").build().unwrap();

// creating read only transaction
// read only ransaction will be automatically rolled back
let mut tx = db.begin_tx().unwrap();

// getting bucket
let flowers = tx.bucket(b"flowers").unwrap();
let data = flowers.get(b"iris").unwrap();
assert_eq!(
  data,
  &b"song by American alternative rock band Goo Goo Dolls"[..]
);

Getting available buckets

use nut::DBBuilder;

let mut db = DBBuilder::new("test.db").build().unwrap();
let mut tx = db.begin_tx().unwrap();

{
  // .buckets() available to conveniently retrieve all buckets keys
  let bucket_names = tx.buckets(); // returns Vec<Vec<u8>>

  // bucket key is any binary data, not only string
  assert_eq!(bucket_names, vec!["flowers".as_bytes().to_vec()]);
}

{
  // additionally there is .cursor() method
  // that returns Cursor struct,
  // which is able to iterate through bucket contents
  let cursor = tx.cursor();

  assert_eq!(
    &cursor.first().unwrap().value.unwrap(),
    &"flowers".as_bytes()
  );
}

Structs

• Bucket
  Bucket represents a collection of key/value pairs inside the database.
• BucketStats
  Records statistics about resources used by a bucket.
• CheckMode
  Defines when db check will occur
• Cursor
  Cursor represents an iterator that can traverse over all key/value pairs in a bucket in sorted order. Cursors see nested buckets with value == None. Cursors can be obtained from a transaction and are valid as long as the transaction is open.
• CursorItem
  Contains references to retrieved bucket’s item key, value and flags
• DB
  Database
• DBBuilder
  Struct to construct database
• DBStats
  Stats represents statistics about the database.
• Flags
  Defines type of the page
• RWTxGuard
  Guard returned by DB.begin_rw_tx()
• Tx
  Transaction
• TxGuard
  Guard returned by DB.begin_tx()
• TxStats
  Transaction statistics

Enums

• Error
  These error can be returned when opening or calling methods on a DB, Transaction etc…
• FreedOrPageInfo