Enum Buffer 

pub enum Buffer {
    InMemory(Vec<u8>),
    Spilled {
        writer: BufWriter<NamedTempFile>,
        len: u64,
    },
}

The buffered input. Transitions from in-memory to spilled as data accumulates.

Variants

InMemory(Vec<u8>)

In-memory accumulation (small inputs).

Spilled

Spilled-to-tempfile accumulation (large inputs).

Fields

writer: BufWriter<NamedTempFile>

len: u64

Tracked size in bytes (since BufWriter writes are not all flushed yet).

Implementations

impl Buffer

pub fn new() -> Self

Construct an empty in-memory buffer with no preallocation.

pub fn len(&self) -> u64

Return the current logical length of the buffered bytes.

pub fn is_empty(&self) -> bool

True iff no bytes have been appended to this buffer.

pub fn drain_reader<R: Read>( &mut self, reader: R, threshold: usize, spill_dir: &Path, ) -> Result<()>

Drain the entire reader into this buffer, transitioning to the spilled variant when the accumulated size would exceed threshold.

spill_dir is the directory in which the spill tempfile is created when the transition triggers. Caller MUST pass the target file’s parent directory (HINT-002).

On the binary path (feature cli), the loop polls the process-wide cancellation flag between chunks; if a signal was delivered, the drain returns io::ErrorKind::Interrupted so the in-progress tempfile is dropped via the normal Drop chain before exit.

pub fn append( &mut self, bytes: &[u8], threshold: usize, spill_dir: &Path, ) -> Result<()>

Append a slice of bytes, transitioning to spilled storage if doing so would push the buffer past threshold.

pub fn transition_to_spilled(&mut self, spill_dir: &Path) -> Result<()>

Promote an InMemory buffer to a Spilled one, flushing the existing bytes into the new tempfile. No-op if already spilled.

pub fn write_to<W: Write>(self, out: W) -> Result<()>

Consume the buffer and write its bytes to out. Implementations:

• InMemory: a single write_all of the Vec.
• Spilled: flush BufWriter, rewind the NamedTempFile to start, copy through to out in 64 KiB chunks.

Trait Implementations

impl Default for Buffer

fn default() -> Self

Returns the “default value” for a type.