Struct MmapReplayBuffer 

pub struct MmapReplayBuffer { /* private fields */ }

When replay buffer exceeds RAM capacity, transparently spill to disk. Uses mmap for lazy loading – only pages actually accessed are read.

Architecture:

• hot: in-memory ReplayBuffer for recent data (fast sampling)
• cold: memory-mapped file for overflow data (ring-buffer with wrapping)
• Sampling prefers hot data but can reach into cold

Implementations

impl MmapReplayBuffer

pub fn new( hot_capacity: usize, total_capacity: usize, obs_dim: usize, act_dim: usize, cold_path: PathBuf, ) -> Result<Self, RloxError>

Create a new mmap-backed replay buffer.

hot_capacity records are kept in memory. When exceeded, the oldest hot records spill to the cold file at cold_path. The total number of records stored (hot + cold) is capped at total_capacity.

pub fn len(&self) -> usize

Total number of records stored (hot + cold).

pub fn is_empty(&self) -> bool

Whether the buffer contains no records.

pub fn push(&mut self, record: ExperienceRecord) -> Result<(), RloxError>

Push a record. If the hot buffer is full, the oldest hot record is spilled to cold storage before the new record is inserted.

pub fn push_batch( &mut self, obs_batch: &[f32], next_obs_batch: &[f32], actions_batch: &[f32], rewards: &[f32], terminated: &[f32], truncated: &[f32], ) -> Result<(), RloxError>

Push multiple transitions at once from flat arrays.

obs_batch shape: [n * obs_dim], next_obs_batch: same, actions_batch: [n * act_dim], others: [n].

terminated / truncated convention

These take &[f32] (not bool) for compatibility with numpy arrays from the Python side. Non-zero values are treated as true. This differs from push which accepts native bool.

pub fn sample( &mut self, batch_size: usize, seed: u64, ) -> Result<SampledBatch, RloxError>

Sample batch_size records uniformly from hot + cold storage. Uses ChaCha8Rng seeded with seed for deterministic reproducibility.

pub fn close(&mut self) -> Result<(), RloxError>

Unmap the cold file and delete it from disk.

Trait Implementations

impl Debug for MmapReplayBuffer

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

Formats the value using the given formatter.

impl Drop for MmapReplayBuffer

fn drop(&mut self)

Executes the destructor for this type.