Safe Rust bindings for LMDB with encryption at rest
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lmdb-rs/src/database.rs

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3.1 KiB

use std::ptr;
use ffi;
use error::{LmdbResult, lmdb_result};
use flags::DatabaseFlags;
use transaction::{RwTransaction, Transaction};
/// A handle to an individual database in an environment.
///
/// A database handle denotes the name and parameters of a database in an environment.
#[deriving(Show, Clone, Copy, Eq, PartialEq)]
pub struct Database {
dbi: ffi::MDB_dbi,
}
impl Database {
/// Opens a database in the provided transaction.
///
/// If `name` is `None`, then the default database will be opened, otherwise a named database
/// will be opened. The database handle will be private to the transaction until the transaction
/// is successfully committed. If the transaction is aborted the returned database handle
/// should no longer be used.
///
/// ## Unsafety
///
/// * This function (as well as `Environment::open_db`, `Environment::create_db`, and
/// `Database::create`) **must not** be called from multiple concurrent transactions in the same
/// environment. A transaction which uses this function must finish (either commit or abort)
/// before any other transaction may use this function.
pub unsafe fn open(txn: &Transaction,
name: Option<&str>)
-> LmdbResult<Database> {
let c_name = name.map(|n| n.to_c_str());
let name_ptr = if let Some(ref c_name) = c_name { c_name.as_ptr() } else { ptr::null() };
let mut dbi: ffi::MDB_dbi = 0;
try!(lmdb_result(ffi::mdb_dbi_open(txn.txn(), name_ptr, 0, &mut dbi)));
Ok(Database { dbi: dbi })
}
/// Opens a handle in the provided transaction, creating the database if necessary.
///
/// If `name` is `None`, then the default database will be opened, otherwise a named database
/// will be opened. The database handle will be private to the transaction until the transaction
/// is successfully committed. If the transaction is aborted the returned database handle
/// should no longer be used.
///
/// ## Unsafety
///
/// * This function (as well as `Environment::open_db`, `Environment::create_db`, and
/// `Database::open`) **must not** be called from multiple concurrent transactions in the same
/// environment. A transaction which uses this function must finish (either commit or abort)
/// before any other transaction may use this function.
pub unsafe fn create(txn: &RwTransaction,
name: Option<&str>,
flags: DatabaseFlags)
-> LmdbResult<Database> {
let c_name = name.map(|n| n.to_c_str());
let name_ptr = if let Some(ref c_name) = c_name { c_name.as_ptr() } else { ptr::null() };
let mut dbi: ffi::MDB_dbi = 0;
try!(lmdb_result(ffi::mdb_dbi_open(txn.txn(), name_ptr, flags.bits() | ffi::MDB_CREATE, &mut dbi)));
Ok(Database { dbi: dbi })
}
/// Returns the underlying LMDB database handle.
///
/// The caller **must** ensure that the handle is not used after the lifetime of the
/// environment, or after the database handle has been closed.
pub fn dbi(&self) -> ffi::MDB_dbi {
self.dbi
}
}