Struct SnapshotWithThreadMode 

pub struct SnapshotWithThreadMode<'a, D: DBAccess> { /* private fields */ }

A consistent view of the database at the point of creation.

Examples

use rust_rocksdb::{DB, IteratorMode, Options};

let tempdir = tempfile::Builder::new()
    .prefix("_path_for_rocksdb_storage3")
    .tempdir()
    .expect("Failed to create temporary path for the _path_for_rocksdb_storage3");
let path = tempdir.path();
{
    let db = DB::open_default(path).unwrap();
    let snapshot = db.snapshot(); // Creates a longer-term snapshot of the DB, but closed when goes out of scope
    let mut iter = snapshot.iterator(IteratorMode::Start); // Make as many iterators as you'd like from one snapshot
}
let _ = DB::destroy(&Options::default(), path);

A Snapshot must not outlive the DB it was created from:

use rust_rocksdb::DB;

let _snapshot = {
    let db = DB::open_default("foo").unwrap();
    db.snapshot()
};

An iterator created from a snapshot must not outlive the snapshot either: RocksDB keeps the const Snapshot* inside the iterator’s ReadOptions.

use rust_rocksdb::{DB, IteratorMode};

let db = DB::open_default("foo").unwrap();
let mut iter = {
    let snapshot = db.snapshot();
    snapshot.iterator(IteratorMode::Start)
};
let _ = iter.next();

Implementations

impl<'a, D: DBAccess> SnapshotWithThreadMode<'a, D>

pub fn new(db: &'a D) -> Self

Creates a new SnapshotWithThreadMode of the database db.

pub fn sequence_number(&self) -> Option<u64>

Returns the sequence number of the snapshot, or None if there is no underlying snapshot.

A Transaction that was not started with TransactionOptions::set_snapshot(true) still hands out a snapshot handle, but that handle wraps a null rocksdb::Snapshot*. Upstream’s rocksdb_snapshot_get_sequence_number dereferences it unconditionally, so this used to be a null dereference reachable from safe code:

let txn = db.transaction(); // no set_snapshot(true)
assert_eq!(txn.snapshot().sequence_number(), None);

pub fn read_options(&self) -> SnapshotReadOptions<'_, 'a, D>

Creates reusable default read options bound to this snapshot.

pub fn read_options_opt( &self, readopts: ReadOptions, ) -> SnapshotReadOptions<'_, 'a, D>

Creates reusable custom read options bound to this snapshot.

Any snapshot already configured on readopts is replaced with this snapshot.

pub fn iterator( &self, mode: IteratorMode<'_>, ) -> DBIteratorWithThreadMode<'_, D>

Creates an iterator over the data in this snapshot, using the default read options.

The iterator borrows the snapshot: the ReadOptions handed to RocksDB carry a const Snapshot* that the iterator keeps, so it must not outlive the snapshot.

pub fn iterator_cf( &self, cf_handle: &impl AsColumnFamilyRef, mode: IteratorMode<'_>, ) -> DBIteratorWithThreadMode<'_, D>

Creates an iterator over the data in this snapshot under the given column family, using the default read options.

pub fn iterator_opt( &self, mode: IteratorMode<'_>, readopts: ReadOptions, ) -> DBIteratorWithThreadMode<'_, D>

Creates an iterator over the data in this snapshot, using the given read options.

The iterator borrows the snapshot; see Self::iterator.

pub fn iterator_cf_opt( &self, cf_handle: &impl AsColumnFamilyRef, readopts: ReadOptions, mode: IteratorMode<'_>, ) -> DBIteratorWithThreadMode<'_, D>

Creates an iterator over the data in this snapshot under the given column family, using the given read options.

pub fn raw_iterator(&self) -> DBRawIteratorWithThreadMode<'_, D>

Creates a raw iterator over the data in this snapshot, using the default read options.

pub fn raw_iterator_cf( &self, cf_handle: &impl AsColumnFamilyRef, ) -> DBRawIteratorWithThreadMode<'_, D>

Creates a raw iterator over the data in this snapshot under the given column family, using the default read options.

pub fn raw_iterator_opt( &self, readopts: ReadOptions, ) -> DBRawIteratorWithThreadMode<'_, D>

Creates a raw iterator over the data in this snapshot, using the given read options.

pub fn raw_iterator_cf_opt( &self, cf_handle: &impl AsColumnFamilyRef, readopts: ReadOptions, ) -> DBRawIteratorWithThreadMode<'_, D>

Creates a raw iterator over the data in this snapshot under the given column family, using the given read options.

pub fn get<K: AsRef<[u8]>>(&self, key: K) -> Result<Option<Vec<u8>>, Error>

Returns the bytes associated with a key value with default read options.

pub fn get_cf<K: AsRef<[u8]>>( &self, cf: &impl AsColumnFamilyRef, key: K, ) -> Result<Option<Vec<u8>>, Error>

Returns the bytes associated with a key value and given column family with default read options.

pub fn get_opt<K: AsRef<[u8]>>( &self, key: K, readopts: ReadOptions, ) -> Result<Option<Vec<u8>>, Error>

Returns the bytes associated with a key value and given read options.

pub fn get_cf_opt<K: AsRef<[u8]>>( &self, cf: &impl AsColumnFamilyRef, key: K, readopts: ReadOptions, ) -> Result<Option<Vec<u8>>, Error>

Returns the bytes associated with a key value, given column family and read options.

pub fn get_pinned<K: AsRef<[u8]>>( &self, key: K, ) -> Result<Option<DBPinnableSlice<'_>>, Error>

Return the value associated with a key using RocksDB’s PinnableSlice so as to avoid unnecessary memory copy. Similar to get_pinned_opt but leverages default options.

pub fn get_pinned_cf<K: AsRef<[u8]>>( &self, cf: &impl AsColumnFamilyRef, key: K, ) -> Result<Option<DBPinnableSlice<'_>>, Error>

Return the value associated with a key using RocksDB’s PinnableSlice so as to avoid unnecessary memory copy. Similar to get_pinned_cf_opt but leverages default options.

pub fn get_pinned_opt<K: AsRef<[u8]>>( &self, key: K, readopts: ReadOptions, ) -> Result<Option<DBPinnableSlice<'_>>, Error>

Return the value associated with a key using RocksDB’s PinnableSlice so as to avoid unnecessary memory copy.

pub fn get_pinned_cf_opt<K: AsRef<[u8]>>( &self, cf: &impl AsColumnFamilyRef, key: K, readopts: ReadOptions, ) -> Result<Option<DBPinnableSlice<'_>>, Error>

Return the value associated with a key using RocksDB’s PinnableSlice so as to avoid unnecessary memory copy. Similar to get_pinned_opt but allows specifying ColumnFamily.

pub fn multi_get<K: AsRef<[u8]>, I>( &self, keys: I, ) -> Vec<Result<Option<Vec<u8>>, Error>>

where I: IntoIterator<Item = K>,

Returns the bytes associated with the given key values and default read options.

pub fn multi_get_cf<'b, K, I, W>( &self, keys_cf: I, ) -> Vec<Result<Option<Vec<u8>>, Error>>

where K: AsRef<[u8]>, I: IntoIterator<Item = (&'b W, K)>, W: AsColumnFamilyRef + 'b,

Returns the bytes associated with the given key values and default read options.

pub fn multi_get_opt<K, I>( &self, keys: I, readopts: ReadOptions, ) -> Vec<Result<Option<Vec<u8>>, Error>>

where K: AsRef<[u8]>, I: IntoIterator<Item = K>,

Returns the bytes associated with the given key values and given read options.

pub fn multi_get_cf_opt<'b, K, I, W>( &self, keys_cf: I, readopts: ReadOptions, ) -> Vec<Result<Option<Vec<u8>>, Error>>

where K: AsRef<[u8]>, I: IntoIterator<Item = (&'b W, K)>, W: AsColumnFamilyRef + 'b,

Returns the bytes associated with the given key values, given column family and read options.

Trait Implementations

impl<D: DBAccess> Drop for SnapshotWithThreadMode<'_, D>

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.

impl<D: DBAccess + Sync> Send for SnapshotWithThreadMode<'_, D>

Send and Sync implementations for SnapshotWithThreadMode are safe, because SnapshotWithThreadMode is immutable and can be safely shared between threads.

impl<D: DBAccess + Sync> Sync for SnapshotWithThreadMode<'_, D>