Struct MemoryWriter 

pub struct MemoryWriter { /* private fields */ }

Memory file writer — wraps an AtomicWriter so the staged file is renamed onto the destination on commit.

Implementations

impl MemoryWriter

pub fn open( dest: &Path, ram_size: u64, page_size: u64, ) -> Result<Self, SnapshotError>

Open a memory writer for the destination path.

ram_size is the logical size; for Full snapshots the file ends up exactly this large, for Diff it ends up sparse with the same logical extent. page_size is the memory-file page size — typically the host page (16 KiB on Apple Silicon) so the file aligns with pwrite granularity.

Errors

As AtomicWriter::open.

pub fn ram_size(&self) -> u64

The on-disk extent the file represents.

pub fn page_size(&self) -> u64

The memory-file page size in bytes.

pub fn write_full<R: PageReader>( &mut self, reader: &R, ) -> Result<(), SnapshotError>

Write a Full dump: every byte of [0, ram_size) from reader is written.

We chunk in page_size units so the writer never holds the whole memory in a buffer; this matches the production path where applevisor::Memory::read is the upstream of read_at.

Errors

SnapshotError::MemoryIo for any read or write failure.

pub fn write_diff<R: PageReader>( &mut self, reader: &R, dirty: &DirtyBitmap, ) -> Result<u64, SnapshotError>

Write a Diff dump: only the pages in dirty are pwritten at their offsets.

The file’s logical extent ends up at ram_size. Filesystem-level holes will cover the unmodified pages on APFS, HFS+, and exFAT (per § 7 — “sparse file cross-FS”); on NFS we still produce the right bytes, just dense.

dirty must cover the same [ram_start, ram_size) range as the writer, but may have a different page_size: we re-chunk the writes accordingly so the memory file stays at self.page_size granularity even when the bitmap was rebuilt under the adaptive heuristic.

Errors

SnapshotError::MemoryIo for any read or write failure.

pub fn commit(self) -> Result<(), SnapshotError>

fsync + rename the memory file onto the destination.

Errors

As AtomicWriter::commit.

Trait Implementations

impl Debug for MemoryWriter

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

Formats the value using the given formatter.