Struct CheckpointedStageState 

pub struct CheckpointedStageState<T> { /* private fields */ }

A stage state wrapper with durable checkpoint/restore support.

Serializes the state to a BlockLease on checkpoint and deserializes on restore, using a format compatible with the grafos-collections Durable pattern.

Fail-closed

If a checkpoint write fails, the error is propagated immediately. Callers should halt the stage rather than continue with an uncheckpointed state.

Implementations

impl<T: Serialize + DeserializeOwned> CheckpointedStageState<T>

pub fn new(state: T, block_lease: BlockLease) -> Self

Create a new checkpointed state wrapper.

Does not write an initial checkpoint. Call checkpoint to persist.

pub fn checkpoint(&mut self) -> Result<(), EdgeError>

Serialize the current state to block storage.

Uses a header block + data block layout:

• Block 0: magic (4) + version (4) + data_len (8)
• Blocks 1..N: postcard-serialized state bytes

Errors

Returns EdgeError::CheckpointFailed on serialization or I/O failure.

pub fn restore(block_lease: BlockLease) -> Result<Self, EdgeError>

Restore a checkpointed state from block storage.

Reads the header block to determine data length, then reads and deserializes the state from the data blocks.

Errors

Returns EdgeError::CheckpointFailed on corrupt data, version mismatch, or deserialization failure.

pub fn state(&self) -> &T

Borrow the current state.

pub fn state_mut(&mut self) -> &mut T

Mutably borrow the current state.

pub fn into_block_lease(self) -> BlockLease

Consume the wrapper and return the underlying block lease.

This allows transferring the lease to a subsequent restore call so that both sides access the same underlying block storage.