State persistence

Checkpoints#

The EVM state also needs to survive restarts.

Solizone EVM uses SolizoneCheckpoint.

A checkpoint contains:

SolizoneCheckpoint
├── StateSnapshot
├── next_height
└── parent_hash

So the checkpoint captures both:

execution state

and

chain position

Together they answer:

What does the EVM currently look like?

and

Where should the next block continue from?

State snapshots#

A StateSnapshot is a deterministic representation of the current EVM state.

It can include:

accounts
balances
nonces
contract bytecode
contract storage

The snapshot can be serialized.

Later:

snapshot
   ↓
decode
   ↓
new MemoryState

This lets a completely new process reconstruct the execution environment.

Snapshot commitment vs state root#

These two are intentionally separate.

State root

current protocol state
      ↓
state_root

Used for execution and block correctness.

Snapshot commitment

serialized snapshot
      ↓
Keccak256
      ↓
snapshot_commitment

Used to fingerprint persisted state.

They may describe related information, but they serve different jobs.

Persistence backends#

Solizone EVM keeps persistence behind interfaces.

For checkpoints:

CheckpointBackend
├── FileCheckpointBackend
└── LogosStorageCheckpointBackend

This is important because the execution layer should not care where the checkpoint lives.

From the node's perspective:

checkpoint_backend.save(checkpoint)

could mean:

write to disk

or:

upload to Logos Storage

without changing REVM itself.