Struct RwTransaction

pub struct RwTransaction<'env> { /* private fields */ }

An LMDB read-write transaction.

Implementations

impl<'env> RwTransaction<'env>

pub unsafe fn create_db( &self, name: Option<&str>, flags: DatabaseFlags, ) -> Result<Database>

Opens a database in the provided transaction, creating it 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.

Prefer using Environment::create_db.

Safety

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 fn open_rw_cursor<'txn>( &'txn mut self, db: Database, ) -> Result<RwCursor<'txn>>

Opens a new read-write cursor on the given database and transaction.

pub fn put<K, D>( &mut self, database: Database, key: &K, data: &D, flags: WriteFlags, ) -> Result<()>

where K: AsRef<[u8]>, D: AsRef<[u8]>,

Stores an item into a database.

This function stores key/data pairs in the database. The default behavior is to enter the new key/data pair, replacing any previously existing key if duplicates are disallowed, or adding a duplicate data item if duplicates are allowed (DatabaseFlags::DUP_SORT).

pub fn reserve<'txn, K>( &'txn mut self, database: Database, key: &K, len: size_t, flags: WriteFlags, ) -> Result<&'txn mut [u8]>

where K: AsRef<[u8]>,

Returns a buffer which can be used to write a value into the item at the given key and with the given length. The buffer must be completely filled by the caller.

pub fn del<K>( &mut self, database: Database, key: &K, data: Option<&[u8]>, ) -> Result<()>

where K: AsRef<[u8]>,

Deletes an item from a database.

This function removes key/data pairs from the database. If the database does not support sorted duplicate data items (DatabaseFlags::DUP_SORT) the data parameter is ignored. If the database supports sorted duplicates and the data parameter is None, all of the duplicate data items for the key will be deleted. Otherwise, if the data parameter is Some only the matching data item will be deleted. This function will return Error::NotFound if the specified key/data pair is not in the database.

pub fn clear_db(&mut self, db: Database) -> Result<()>

Empties the given database. All items will be removed.

pub unsafe fn drop_db(&mut self, db: Database) -> Result<()>

Drops the database from the environment.

Safety

This method is unsafe in the same ways as Environment::close_db, and should be used accordingly.

pub fn begin_nested_txn<'txn>(&'txn mut self) -> Result<RwTransaction<'txn>>

Begins a new nested transaction inside of this transaction.

Trait Implementations

impl<'env> Debug for RwTransaction<'env>

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'env> Drop for RwTransaction<'env>

fn drop(&mut self)

Executes the destructor for this type.

impl<'env> Transaction for RwTransaction<'env>

fn txn(&self) -> *mut MDB_txn

Returns a raw pointer to the underlying LMDB transaction.

fn commit(self) -> Result<()>

Commits the transaction.

fn abort(self)

Aborts the transaction.

unsafe fn open_db(&self, name: Option<&str>) -> Result<Database>

Opens a database in the transaction.

fn get<'txn, K>(&'txn self, database: Database, key: &K) -> Result<&'txn [u8]>

where K: AsRef<[u8]>,

Gets an item from a database.

fn open_ro_cursor<'txn>(&'txn self, db: Database) -> Result<RoCursor<'txn>>

Open a new read-only cursor on the given database.

fn db_flags(&self, db: Database) -> Result<DatabaseFlags>

Gets the option flags for the given database in the transaction.

fn stat(&self, db: Database) -> Result<Stat>

Retrieves database statistics.