Struct LazyWalReader 

pub struct LazyWalReader { /* private fields */ }

Lazy WAL reader that separates header reading from payload reading.

Implementations

impl LazyWalReader

pub fn open(path: &Path, keys: Option<&KeyRing>) -> Result<Self>

Open a WAL file for lazy reading.

A leading WALP preamble is consumed so headers are read from the first real record; segments written without encryption have none and start at offset 0.

keys must be the key ring this segment was written under, or None for a segment that was never encrypted.

pub fn segment_preamble(&self) -> Option<&SegmentPreamble>

The preamble read from this segment file, if present.

Returns None for unencrypted segments (no preamble written).

pub fn stop_reason(&self) -> Option<StopReason>

Why iteration stopped, or None while headers are still being read.

Feed this to crate::torn_tail::verify_committed_prefix to tell an unfsynced tail apart from a hole with committed records behind it.

pub fn next_header(&mut self) -> Result<Option<RecordHeader>>

Read the next record header without reading the payload.

Returns None at EOF or first corruption. Returns Err for a format version this build cannot read at the segment’s first record, and the caller must stop at that Err. After a header, use either read_payload() to get the payload or skip_payload() to seek past it.

Alignment padding records are consumed internally — the caller only ever sees real records.

pub fn read_payload(&mut self, header: &RecordHeader) -> Result<Vec<u8>>

Read the payload for a header that was just returned by next_header(), decrypting it if the record is encrypted.

Must be called exactly once after next_header() returns Some, and before calling next_header() again (unless skip_payload() was called instead).

pub fn read_record(&mut self, header: &RecordHeader) -> Result<WalRecord>

Read the payload and return a full plaintext WalRecord.

The returned record is indistinguishable from one written without encryption: the flag is cleared and the CRC is recomputed, so downstream logical_record_type() dispatch and verify_checksum() both hold.

pub fn skip_payload(&mut self, header: &RecordHeader) -> Result<()>

Skip the payload for a header, seeking forward without reading.

This is the key optimization: non-matching records skip I/O entirely.

pub fn offset(&self) -> u64

Current file offset.