Struct OpLog 

pub struct OpLog { /* private fields */ }

In-memory Merkle-DAG operation log.

Append-only: entries are content-addressed and linked to their causal predecessors (the heads at time of write). The OpLog tracks heads, supports delta computation (entries_since), and topological sorting.

Implementations

impl OpLog

pub fn new(genesis: Entry) -> Self

Create a new OpLog with a genesis entry.

pub fn append(&mut self, entry: Entry) -> Result<bool, OpLogError>

Append an entry to the log.

• Verifies the entry hash is valid.
• If the entry already exists (duplicate), returns false.
• Updates heads: the entry’s next links are no longer heads (they have a successor).
• Returns true if the entry was newly inserted.

pub fn heads(&self) -> Vec<Hash>

Current DAG head hashes.

pub fn get(&self, hash: &Hash) -> Option<&Entry>

Get an entry by hash.

pub fn len(&self) -> usize

Total entries in the log.

pub fn is_empty(&self) -> bool

Whether the log is empty (should never be — always has genesis).

pub fn estimated_memory_bytes(&self) -> usize

Approximate heap memory used by the oplog (bytes). Uses serialized entry sizes + fixed overhead estimates per structure. Does not account for heap allocations behind String/Vec in property values or allocator fragmentation. Actual memory may be 2-3x higher for string-heavy graphs.

pub fn verify_integrity(&self) -> Vec<String>

Verify structural integrity of the oplog (INV-6). Checks I-01 (hash integrity), I-02 (causal completeness), I-04 (heads accuracy). Returns a list of errors (empty = healthy).

pub fn entries_since(&self, known_hash: Option<&Hash>) -> Vec<&Entry>

Return all entries reachable from current heads that are NOT reachable from (or equal to) known_hash.

This computes the delta a peer needs: “give me everything you have that I don’t, given that I already have known_hash and its ancestors.”

If known_hash is None, returns all entries (the entire log).

pub fn topo_sort(&self, hashes: &HashSet<Hash>) -> Vec<&Entry>

Topological sort of the given set of entry hashes. Returns entries in causal order: parents before children.

pub fn entries_as_of( &self, cutoff_physical: u64, cutoff_logical: u32, ) -> Vec<&Entry>

R-06: Get all entries with clock <= cutoff, in topological order. Returns a historical snapshot of the state at the given time.

pub fn replace_with_checkpoint(&mut self, checkpoint: Entry)

R-08: Replace entire oplog with a single checkpoint entry. All previous entries are removed. The checkpoint becomes the sole entry. SAFETY: Only call after verifying ALL peers have synced past all current entries.