Struct PooledIterator

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pub struct PooledIterator { /* private fields */ }

Expand description

A pooled iterator that automatically returns to the global pool on drop.

Wraps a DBIterator and implements Deref/DerefMut so it can be used identically. When dropped, the iterator is reset (releasing Arc<TableReader> references) and returned to the global pool for reuse by any thread.

Implementations§

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impl PooledIterator

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pub fn new(iter: DBIterator) -> Self

Wrap a DBIterator for automatic pool return on drop.

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pub fn into_inner(self) -> DBIterator ⓘ

Take ownership of the inner iterator, disabling automatic pool return.

Methods from Deref<Target = DBIterator>§

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pub fn reset(&mut self, sources: Vec<IterSource>, sequence: SequenceNumber)

Reset the iterator with new sources and sequence, reusing allocated memory. Used by the iterator pool to avoid per-iteration allocation overhead.

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pub fn reset_with_prefix( &mut self, sources: Vec<IterSource>, sequence: SequenceNumber, prefix: Vec<u8>, )

Reset with prefix-bounded iteration, reusing allocated memory.

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pub fn set_range_tombstones( &mut self, tombstones: Vec<(Vec<u8>, Vec<u8>, SequenceNumber)>, )

Set pre-collected range tombstones. Called by the DB layer after collecting tombstones from all memtables and SST files.

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pub fn set_range_tombstones_with_levels( &mut self, tombstones: Vec<(Vec<u8>, Vec<u8>, SequenceNumber, usize)>, )

Set range tombstones with level info for cross-level pruning. A tombstone from level L can only delete keys from levels > L.

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pub fn set_no_range_deletions(&mut self)

No-op: tombstones are loaded upfront; emptiness is checked via is_empty().

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pub fn set_upper_bound(&mut self, bound: Vec<u8>)

Set an exclusive upper bound on user keys. Iteration stops when user key >= this bound. Models RocksDB’s ReadOptions::iterate_upper_bound.

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pub fn set_lower_bound(&mut self, bound: Vec<u8>)

Set an inclusive lower bound on user keys.

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pub fn set_bounds(&mut self, lower: Option<Vec<u8>>, upper: Option<Vec<u8>>)

Set both lower (inclusive) and upper (exclusive) bounds on user keys.

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pub fn error(&self) -> Option<String>

Return the first error from any underlying source iterator. Use after iteration returns None to distinguish normal exhaustion from I/O failures.

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pub fn set_skip_point(&mut self, f: SkipPointFn)

Set a skip-point callback. During iteration, any user key for which the callback returns true is silently skipped.

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pub fn next_prefix(&mut self, prefix_len: usize)

Jump to the first key of the next prefix, skipping all remaining keys under the current prefix in O(log N) instead of O(keys_in_prefix). prefix_len is the number of bytes that define a prefix.

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pub fn seek(&mut self, target: &[u8])

Seek to the first key >= target.

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pub fn seek_to_first(&mut self)

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pub fn reset_and_seek_to_first(&mut self)

Fully reset internal deduplication/tombstone state, then seek to first. Used by BidiIterator when materializing after a seek_to_last().

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pub fn seek_for_prev(&mut self, target: &[u8])

Seek to the last visible user key <= target.

Uses a single backward seek + inline resolution. No redundant forward seek.

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pub fn prev(&mut self)

Move to the previous visible user key.

Uses inline backward resolution: O(1) amortized per call.

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pub fn seek_to_last(&mut self)

Seek to the last visible key. Positions the iterator on the very last entry.

If a prefix is set, seeks to the last key within the prefix. Uses merger backward seek to find the last user key efficiently, then resolves visibility inline (no forward re-seek).

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