Struct WriteBatch 

pub struct WriteBatch { /* private fields */ }

Batch of write operations applied with a shared seqno.

Duplicate keys: all entries receive the same seqno. The memtable skiplist orders by (user_key, Reverse(seqno)) — value_type does NOT break ties. Two entries with the same (user_key, seqno) compare equal regardless of operation type, so one may silently overwrite the other.

• Repeated merge() on the same key: safe. All merge operands are collected during reads regardless of skiplist position.
• Mixed ops on the same key (e.g. insert + remove): not allowed. materialize() rejects these batches with Error::MixedOperationBatch in all builds. Callers must canonicalize mixed-op duplicates into a single final operation before batching.

Examples

use lsm_tree::WriteBatch;

let mut batch = WriteBatch::new();
batch.insert("key1", "value1");
batch.insert("key2", "value2");
batch.remove("key3");

assert_eq!(batch.len(), 3);
assert!(!batch.is_empty());

Implementations

impl WriteBatch

pub fn new() -> Self

Creates an empty write batch.

pub fn with_capacity(capacity: usize) -> Self

Creates an empty write batch with the given capacity.

pub fn insert<K: Into<UserKey>, V: Into<UserValue>>(&mut self, key: K, value: V)

Inserts a key-value pair into the batch.

pub fn remove<K: Into<UserKey>>(&mut self, key: K)

Adds a delete (tombstone) for a key.

pub fn remove_weak<K: Into<UserKey>>(&mut self, key: K)

Adds a weak delete (single-delete tombstone) for a key.

pub fn merge<K: Into<UserKey>, V: Into<UserValue>>(&mut self, key: K, value: V)

Adds a merge operand for a key.

Multiple merge() calls for the same key within one batch are supported: they produce distinct merge operands that are resolved together during reads (via the configured MergeOperator). The duplicate-key warning in the struct doc applies to mixed operation types (e.g. insert + remove on the same key), not to multiple merges.

pub fn len(&self) -> usize

Returns the number of operations in the batch.

pub fn is_empty(&self) -> bool

Returns true if the batch contains no operations.

pub fn clear(&mut self)

Clears the batch, removing all entries.

Trait Implementations

impl Clone for WriteBatch

fn clone(&self) -> WriteBatch

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for WriteBatch

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

Formats the value using the given formatter.

impl Default for WriteBatch

fn default() -> WriteBatch

Returns the “default value” for a type.