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use libc::{
c_uint,
c_void,
size_t,
};
use std::marker::PhantomData;
use std::{
fmt,
mem,
ptr,
result,
slice,
};
use ffi;
use cursor::{
RoCursor,
RwCursor,
};
use database::Database;
use environment::{
Environment,
Stat,
};
use error::{
lmdb_result,
Error,
Result,
};
use flags::{
DatabaseFlags,
EnvironmentFlags,
WriteFlags,
};
/// An LMDB transaction.
///
/// All database operations require a transaction.
pub trait Transaction: Sized {
/// Returns a raw pointer to the underlying LMDB transaction.
///
/// The caller **must** ensure that the pointer is not used after the
/// lifetime of the transaction.
fn txn(&self) -> *mut ffi::MDB_txn;
/// Commits the transaction.
///
/// Any pending operations will be saved.
fn commit(self) -> Result<()> {
unsafe {
let result = lmdb_result(ffi::mdb_txn_commit(self.txn()));
mem::forget(self);
result
}
}
/// Aborts the transaction.
///
/// Any pending operations will not be saved.
fn abort(self) {
// Abort should be performed in transaction destructors.
}
/// Opens a database in the 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.
///
/// Prefer using `Environment::open_db`.
///
/// ## Safety
///
/// 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.
unsafe fn open_db(&self, name: Option<&str>) -> Result<Database> {
Database::new(self.txn(), name, 0)
}
/// Gets an item from a database.
///
/// This function retrieves the data associated with the given key in the
/// database. If the database supports duplicate keys
/// (`DatabaseFlags::DUP_SORT`) then the first data item for the key will be
/// returned. Retrieval of other items requires the use of
/// `Transaction::cursor_get`. If the item is not in the database, then
/// `Error::NotFound` will be returned.
fn get<'txn, K>(&'txn self, database: Database, key: &K) -> Result<&'txn [u8]>
where
K: AsRef<[u8]>,
{
let key = key.as_ref();
let mut key_val: ffi::MDB_val = ffi::MDB_val {
mv_size: key.len() as size_t,
mv_data: key.as_ptr() as *mut c_void,
};
let mut data_val: ffi::MDB_val = ffi::MDB_val {
mv_size: 0,
mv_data: ptr::null_mut(),
};
unsafe {
match ffi::mdb_get(self.txn(), database.dbi(), &mut key_val, &mut data_val) {
ffi::MDB_SUCCESS => Ok(slice::from_raw_parts(data_val.mv_data as *const u8, data_val.mv_size as usize)),
err_code => Err(Error::from_err_code(err_code)),
}
}
}
/// Open a new read-only cursor on the given database.
fn open_ro_cursor<'txn>(&'txn self, db: Database) -> Result<RoCursor<'txn>> {
RoCursor::new(self, db)
}
/// Gets the option flags for the given database in the transaction.
fn db_flags(&self, db: Database) -> Result<DatabaseFlags> {
let mut flags: c_uint = 0;
unsafe {
lmdb_result(ffi::mdb_dbi_flags(self.txn(), db.dbi(), &mut flags))?;
}
Ok(DatabaseFlags::from_bits_truncate(flags))
}
/// Retrieves database statistics.
fn stat(&self, db: Database) -> Result<Stat> {
unsafe {
let mut stat = Stat::new();
lmdb_try!(ffi::mdb_stat(self.txn(), db.dbi(), stat.mdb_stat()));
Ok(stat)
}
}
}
/// An LMDB read-only transaction.
pub struct RoTransaction<'env> {
txn: *mut ffi::MDB_txn,
_marker: PhantomData<&'env ()>,
}
impl<'env> fmt::Debug for RoTransaction<'env> {
fn fmt(&self, f: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
f.debug_struct("RoTransaction").finish()
}
}
impl<'env> Drop for RoTransaction<'env> {
fn drop(&mut self) {
unsafe { ffi::mdb_txn_abort(self.txn) }
}
}
impl<'env> RoTransaction<'env> {
/// Creates a new read-only transaction in the given environment. Prefer
/// using `Environment::begin_ro_txn`.
pub(crate) fn new(env: &'env Environment) -> Result<RoTransaction<'env>> {
let mut txn: *mut ffi::MDB_txn = ptr::null_mut();
unsafe {
lmdb_result(ffi::mdb_txn_begin(env.env(), ptr::null_mut(), ffi::MDB_RDONLY, &mut txn))?;
Ok(RoTransaction {
txn,
_marker: PhantomData,
})
}
}
/// Resets the read-only transaction.
///
/// Abort the transaction like `Transaction::abort`, but keep the
/// transaction handle. `InactiveTransaction::renew` may reuse the handle.
/// This saves allocation overhead if the process will start a new read-only
/// transaction soon, and also locking overhead if
/// `EnvironmentFlags::NO_TLS` is in use. The reader table lock is released,
/// but the table slot stays tied to its thread or transaction. Reader locks
/// generally don't interfere with writers, but they keep old versions of
/// database pages allocated. Thus they prevent the old pages from being
/// reused when writers commit new data, and so under heavy load the
/// database size may grow much more rapidly than otherwise.
pub fn reset(self) -> InactiveTransaction<'env> {
let txn = self.txn;
unsafe {
mem::forget(self);
ffi::mdb_txn_reset(txn)
};
InactiveTransaction {
txn,
_marker: PhantomData,
}
}
}
impl<'env> Transaction for RoTransaction<'env> {
fn txn(&self) -> *mut ffi::MDB_txn {
self.txn
}
}
/// An inactive read-only transaction.
pub struct InactiveTransaction<'env> {
txn: *mut ffi::MDB_txn,
_marker: PhantomData<&'env ()>,
}
impl<'env> fmt::Debug for InactiveTransaction<'env> {
fn fmt(&self, f: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
f.debug_struct("InactiveTransaction").finish()
}
}
impl<'env> Drop for InactiveTransaction<'env> {
fn drop(&mut self) {
unsafe { ffi::mdb_txn_abort(self.txn) }
}
}
impl<'env> InactiveTransaction<'env> {
/// Renews the inactive transaction, returning an active read-only
/// transaction.
///
/// This acquires a new reader lock for a transaction handle that had been
/// released by `RoTransaction::reset`.
pub fn renew(self) -> Result<RoTransaction<'env>> {
let txn = self.txn;
unsafe {
mem::forget(self);
lmdb_result(ffi::mdb_txn_renew(txn))?
};
Ok(RoTransaction {
txn,
_marker: PhantomData,
})
}
}
/// An LMDB read-write transaction.
pub struct RwTransaction<'env> {
txn: *mut ffi::MDB_txn,
_marker: PhantomData<&'env ()>,
}
impl<'env> fmt::Debug for RwTransaction<'env> {
fn fmt(&self, f: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
f.debug_struct("RwTransaction").finish()
}
}
impl<'env> Drop for RwTransaction<'env> {
fn drop(&mut self) {
unsafe { ffi::mdb_txn_abort(self.txn) }
}
}
impl<'env> RwTransaction<'env> {
/// Creates a new read-write transaction in the given environment. Prefer
/// using `Environment::begin_ro_txn`.
pub(crate) fn new(env: &'env Environment) -> Result<RwTransaction<'env>> {
let mut txn: *mut ffi::MDB_txn = ptr::null_mut();
unsafe {
lmdb_result(ffi::mdb_txn_begin(env.env(), ptr::null_mut(), EnvironmentFlags::empty().bits(), &mut txn))?;
Ok(RwTransaction {
txn,
_marker: PhantomData,
})
}
}
/// 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 unsafe fn create_db(&self, name: Option<&str>, flags: DatabaseFlags) -> Result<Database> {
Database::new(self.txn(), name, flags.bits() | ffi::MDB_CREATE)
}
/// Opens a new read-write cursor on the given database and transaction.
pub fn open_rw_cursor<'txn>(&'txn mut self, db: Database) -> Result<RwCursor<'txn>> {
RwCursor::new(self, db)
}
/// 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 put<K, D>(&mut self, database: Database, key: &K, data: &D, flags: WriteFlags) -> Result<()>
where
K: AsRef<[u8]>,
D: AsRef<[u8]>,
{
let key = key.as_ref();
let data = data.as_ref();
let mut key_val: ffi::MDB_val = ffi::MDB_val {
mv_size: key.len() as size_t,
mv_data: key.as_ptr() as *mut c_void,
};
let mut data_val: ffi::MDB_val = ffi::MDB_val {
mv_size: data.len() as size_t,
mv_data: data.as_ptr() as *mut c_void,
};
unsafe { lmdb_result(ffi::mdb_put(self.txn(), database.dbi(), &mut key_val, &mut data_val, flags.bits())) }
}
/// 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 reserve<'txn, K>(
&'txn mut self,
database: Database,
key: &K,
len: size_t,
flags: WriteFlags,
) -> Result<&'txn mut [u8]>
where
K: AsRef<[u8]>,
{
let key = key.as_ref();
let mut key_val: ffi::MDB_val = ffi::MDB_val {
mv_size: key.len() as size_t,
mv_data: key.as_ptr() as *mut c_void,
};
let mut data_val: ffi::MDB_val = ffi::MDB_val {
mv_size: len,
mv_data: ptr::null_mut::<c_void>(),
};
unsafe {
lmdb_result(ffi::mdb_put(
self.txn(),
database.dbi(),
&mut key_val,
&mut data_val,
flags.bits() | ffi::MDB_RESERVE,
))?;
Ok(slice::from_raw_parts_mut(data_val.mv_data as *mut u8, data_val.mv_size as usize))
}
}
/// 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 del<K>(&mut self, database: Database, key: &K, data: Option<&[u8]>) -> Result<()>
where
K: AsRef<[u8]>,
{
let key = key.as_ref();
let mut key_val: ffi::MDB_val = ffi::MDB_val {
mv_size: key.len() as size_t,
mv_data: key.as_ptr() as *mut c_void,
};
let data_val: Option<ffi::MDB_val> = data.map(|data| ffi::MDB_val {
mv_size: data.len() as size_t,
mv_data: data.as_ptr() as *mut c_void,
});
if let Some(mut d) = data_val {
unsafe { lmdb_result(ffi::mdb_del(self.txn(), database.dbi(), &mut key_val, &mut d)) }
} else {
unsafe { lmdb_result(ffi::mdb_del(self.txn(), database.dbi(), &mut key_val, ptr::null_mut())) }
}
}
/// Empties the given database. All items will be removed.
pub fn clear_db(&mut self, db: Database) -> Result<()> {
unsafe { lmdb_result(ffi::mdb_drop(self.txn(), db.dbi(), 0)) }
}
/// 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 unsafe fn drop_db(&mut self, db: Database) -> Result<()> {
lmdb_result(ffi::mdb_drop(self.txn, db.dbi(), 1))
}
/// Begins a new nested transaction inside of this transaction.
pub fn begin_nested_txn<'txn>(&'txn mut self) -> Result<RwTransaction<'txn>> {
let mut nested: *mut ffi::MDB_txn = ptr::null_mut();
unsafe {
let env: *mut ffi::MDB_env = ffi::mdb_txn_env(self.txn());
ffi::mdb_txn_begin(env, self.txn(), 0, &mut nested);
}
Ok(RwTransaction {
txn: nested,
_marker: PhantomData,
})
}
}
impl<'env> Transaction for RwTransaction<'env> {
fn txn(&self) -> *mut ffi::MDB_txn {
self.txn
}
}
#[cfg(test)]
mod test {
use std::io::Write;
use std::sync::{
Arc,
Barrier,
};
use std::thread::{
self,
JoinHandle,
};
use tempdir::TempDir;
use super::*;
use cursor::Cursor;
use error::*;
use flags::*;
#[test]
fn test_put_get_del() {
let dir = TempDir::new("test").unwrap();
let env = Environment::new().open(dir.path()).unwrap();
let db = env.open_db(None).unwrap();
let mut txn = env.begin_rw_txn().unwrap();
txn.put(db, b"key1", b"val1", WriteFlags::empty()).unwrap();
txn.put(db, b"key2", b"val2", WriteFlags::empty()).unwrap();
txn.put(db, b"key3", b"val3", WriteFlags::empty()).unwrap();
txn.commit().unwrap();
let mut txn = env.begin_rw_txn().unwrap();
assert_eq!(b"val1", txn.get(db, b"key1").unwrap());
assert_eq!(b"val2", txn.get(db, b"key2").unwrap());
assert_eq!(b"val3", txn.get(db, b"key3").unwrap());
assert_eq!(txn.get(db, b"key"), Err(Error::NotFound));
txn.del(db, b"key1", None).unwrap();
assert_eq!(txn.get(db, b"key1"), Err(Error::NotFound));
}
#[test]
fn test_put_get_del_multi() {
let dir = TempDir::new("test").unwrap();
let env = Environment::new().open(dir.path()).unwrap();
let db = env.create_db(None, DatabaseFlags::DUP_SORT).unwrap();
let mut txn = env.begin_rw_txn().unwrap();
txn.put(db, b"key1", b"val1", WriteFlags::empty()).unwrap();
txn.put(db, b"key1", b"val2", WriteFlags::empty()).unwrap();
txn.put(db, b"key1", b"val3", WriteFlags::empty()).unwrap();
txn.put(db, b"key2", b"val1", WriteFlags::empty()).unwrap();
txn.put(db, b"key2", b"val2", WriteFlags::empty()).unwrap();
txn.put(db, b"key2", b"val3", WriteFlags::empty()).unwrap();
txn.put(db, b"key3", b"val1", WriteFlags::empty()).unwrap();
txn.put(db, b"key3", b"val2", WriteFlags::empty()).unwrap();
txn.put(db, b"key3", b"val3", WriteFlags::empty()).unwrap();
txn.commit().unwrap();
let txn = env.begin_rw_txn().unwrap();
{
let mut cur = txn.open_ro_cursor(db).unwrap();
let iter = cur.iter_dup_of(b"key1");
let vals = iter.map(|x| x.unwrap()).map(|(_, x)| x).collect::<Vec<_>>();
assert_eq!(vals, vec![b"val1", b"val2", b"val3"]);
}
txn.commit().unwrap();
let mut txn = env.begin_rw_txn().unwrap();
txn.del(db, b"key1", Some(b"val2")).unwrap();
txn.del(db, b"key2", None).unwrap();
txn.commit().unwrap();
let txn = env.begin_rw_txn().unwrap();
{
let mut cur = txn.open_ro_cursor(db).unwrap();
let iter = cur.iter_dup_of(b"key1");
let vals = iter.map(|x| x.unwrap()).map(|(_, x)| x).collect::<Vec<_>>();
assert_eq!(vals, vec![b"val1", b"val3"]);
let iter = cur.iter_dup_of(b"key2");
assert_eq!(0, iter.count());
}
txn.commit().unwrap();
}
#[test]
fn test_reserve() {
let dir = TempDir::new("test").unwrap();
let env = Environment::new().open(dir.path()).unwrap();
let db = env.open_db(None).unwrap();
let mut txn = env.begin_rw_txn().unwrap();
{
let mut writer = txn.reserve(db, b"key1", 4, WriteFlags::empty()).unwrap();
writer.write_all(b"val1").unwrap();
}
txn.commit().unwrap();
let mut txn = env.begin_rw_txn().unwrap();
assert_eq!(b"val1", txn.get(db, b"key1").unwrap());
assert_eq!(txn.get(db, b"key"), Err(Error::NotFound));
txn.del(db, b"key1", None).unwrap();
assert_eq!(txn.get(db, b"key1"), Err(Error::NotFound));
}
#[test]
fn test_inactive_txn() {
let dir = TempDir::new("test").unwrap();
let env = Environment::new().open(dir.path()).unwrap();
let db = env.open_db(None).unwrap();
{
let mut txn = env.begin_rw_txn().unwrap();
txn.put(db, b"key", b"val", WriteFlags::empty()).unwrap();
txn.commit().unwrap();
}
let txn = env.begin_ro_txn().unwrap();
let inactive = txn.reset();
let active = inactive.renew().unwrap();
assert!(active.get(db, b"key").is_ok());
}
#[test]
fn test_nested_txn() {
let dir = TempDir::new("test").unwrap();
let env = Environment::new().open(dir.path()).unwrap();
let db = env.open_db(None).unwrap();
let mut txn = env.begin_rw_txn().unwrap();
txn.put(db, b"key1", b"val1", WriteFlags::empty()).unwrap();
{
let mut nested = txn.begin_nested_txn().unwrap();
nested.put(db, b"key2", b"val2", WriteFlags::empty()).unwrap();
assert_eq!(nested.get(db, b"key1").unwrap(), b"val1");
assert_eq!(nested.get(db, b"key2").unwrap(), b"val2");
}
assert_eq!(txn.get(db, b"key1").unwrap(), b"val1");
assert_eq!(txn.get(db, b"key2"), Err(Error::NotFound));
}
#[test]
fn test_clear_db() {
let dir = TempDir::new("test").unwrap();
let env = Environment::new().open(dir.path()).unwrap();
let db = env.open_db(None).unwrap();
{
let mut txn = env.begin_rw_txn().unwrap();
txn.put(db, b"key", b"val", WriteFlags::empty()).unwrap();
txn.commit().unwrap();
}
{
let mut txn = env.begin_rw_txn().unwrap();
txn.clear_db(db).unwrap();
txn.commit().unwrap();
}
let txn = env.begin_ro_txn().unwrap();
assert_eq!(txn.get(db, b"key"), Err(Error::NotFound));
}
#[test]
fn test_drop_db() {
let dir = TempDir::new("test").unwrap();
let env = Environment::new().set_max_dbs(2).open(dir.path()).unwrap();
let db = env.create_db(Some("test"), DatabaseFlags::empty()).unwrap();
{
let mut txn = env.begin_rw_txn().unwrap();
txn.put(db, b"key", b"val", WriteFlags::empty()).unwrap();
txn.commit().unwrap();
}
{
let mut txn = env.begin_rw_txn().unwrap();
unsafe {
txn.drop_db(db).unwrap();
}
txn.commit().unwrap();
}
assert_eq!(env.open_db(Some("test")), Err(Error::NotFound));
}
#[test]
fn test_concurrent_readers_single_writer() {
let dir = TempDir::new("test").unwrap();
let env: Arc<Environment> = Arc::new(Environment::new().open(dir.path()).unwrap());
let n = 10usize; // Number of concurrent readers
let barrier = Arc::new(Barrier::new(n + 1));
let mut threads: Vec<JoinHandle<bool>> = Vec::with_capacity(n);
let key = b"key";
let val = b"val";
for _ in 0..n {
let reader_env = env.clone();
let reader_barrier = barrier.clone();
threads.push(thread::spawn(move || {
let db = reader_env.open_db(None).unwrap();
{
let txn = reader_env.begin_ro_txn().unwrap();
assert_eq!(txn.get(db, key), Err(Error::NotFound));
txn.abort();
}
reader_barrier.wait();
reader_barrier.wait();
{
let txn = reader_env.begin_ro_txn().unwrap();
txn.get(db, key).unwrap() == val
}
}));
}
let db = env.open_db(None).unwrap();
let mut txn = env.begin_rw_txn().unwrap();
barrier.wait();
txn.put(db, key, val, WriteFlags::empty()).unwrap();
txn.commit().unwrap();
barrier.wait();
assert!(threads.into_iter().all(|b| b.join().unwrap()))
}
#[test]
fn test_concurrent_writers() {
let dir = TempDir::new("test").unwrap();
let env = Arc::new(Environment::new().open(dir.path()).unwrap());
let n = 10usize; // Number of concurrent writers
let mut threads: Vec<JoinHandle<bool>> = Vec::with_capacity(n);
let key = "key";
let val = "val";
for i in 0..n {
let writer_env = env.clone();
threads.push(thread::spawn(move || {
let db = writer_env.open_db(None).unwrap();
let mut txn = writer_env.begin_rw_txn().unwrap();
txn.put(db, &format!("{}{}", key, i), &format!("{}{}", val, i), WriteFlags::empty()).unwrap();
txn.commit().is_ok()
}));
}
assert!(threads.into_iter().all(|b| b.join().unwrap()));
let db = env.open_db(None).unwrap();
let txn = env.begin_ro_txn().unwrap();
for i in 0..n {
assert_eq!(format!("{}{}", val, i).as_bytes(), txn.get(db, &format!("{}{}", key, i)).unwrap());
}
}
#[test]
fn test_stat() {
let dir = TempDir::new("test").unwrap();
let env = Environment::new().open(dir.path()).unwrap();
let db = env.create_db(None, DatabaseFlags::empty()).unwrap();
let mut txn = env.begin_rw_txn().unwrap();
txn.put(db, b"key1", b"val1", WriteFlags::empty()).unwrap();
txn.put(db, b"key2", b"val2", WriteFlags::empty()).unwrap();
txn.put(db, b"key3", b"val3", WriteFlags::empty()).unwrap();
txn.commit().unwrap();
{
let txn = env.begin_ro_txn().unwrap();
let stat = txn.stat(db).unwrap();
assert_eq!(stat.entries(), 3);
}
let mut txn = env.begin_rw_txn().unwrap();
txn.del(db, b"key1", None).unwrap();
txn.del(db, b"key2", None).unwrap();
txn.commit().unwrap();
{
let txn = env.begin_ro_txn().unwrap();
let stat = txn.stat(db).unwrap();
assert_eq!(stat.entries(), 1);
}
let mut txn = env.begin_rw_txn().unwrap();
txn.put(db, b"key4", b"val4", WriteFlags::empty()).unwrap();
txn.put(db, b"key5", b"val5", WriteFlags::empty()).unwrap();
txn.put(db, b"key6", b"val6", WriteFlags::empty()).unwrap();
txn.commit().unwrap();
{
let txn = env.begin_ro_txn().unwrap();
let stat = txn.stat(db).unwrap();
assert_eq!(stat.entries(), 4);
}
}
#[test]
fn test_stat_dupsort() {
let dir = TempDir::new("test").unwrap();
let env = Environment::new().open(dir.path()).unwrap();
let db = env.create_db(None, DatabaseFlags::DUP_SORT).unwrap();
let mut txn = env.begin_rw_txn().unwrap();
txn.put(db, b"key1", b"val1", WriteFlags::empty()).unwrap();
txn.put(db, b"key1", b"val2", WriteFlags::empty()).unwrap();
txn.put(db, b"key1", b"val3", WriteFlags::empty()).unwrap();
txn.put(db, b"key2", b"val1", WriteFlags::empty()).unwrap();
txn.put(db, b"key2", b"val2", WriteFlags::empty()).unwrap();
txn.put(db, b"key2", b"val3", WriteFlags::empty()).unwrap();
txn.put(db, b"key3", b"val1", WriteFlags::empty()).unwrap();
txn.put(db, b"key3", b"val2", WriteFlags::empty()).unwrap();
txn.put(db, b"key3", b"val3", WriteFlags::empty()).unwrap();
txn.commit().unwrap();
{
let txn = env.begin_ro_txn().unwrap();
let stat = txn.stat(db).unwrap();
assert_eq!(stat.entries(), 9);
}
let mut txn = env.begin_rw_txn().unwrap();
txn.del(db, b"key1", Some(b"val2")).unwrap();
txn.del(db, b"key2", None).unwrap();
txn.commit().unwrap();
{
let txn = env.begin_ro_txn().unwrap();
let stat = txn.stat(db).unwrap();
assert_eq!(stat.entries(), 5);
}
let mut txn = env.begin_rw_txn().unwrap();
txn.put(db, b"key4", b"val1", WriteFlags::empty()).unwrap();
txn.put(db, b"key4", b"val2", WriteFlags::empty()).unwrap();
txn.put(db, b"key4", b"val3", WriteFlags::empty()).unwrap();
txn.commit().unwrap();
{
let txn = env.begin_ro_txn().unwrap();
let stat = txn.stat(db).unwrap();
assert_eq!(stat.entries(), 8);
}
}
}