neograph::graph::InMemoryCheckpointStore Class Reference

In-memory checkpoint store for testing and single-process use. More...

#include <checkpoint.h>

Inheritance diagram for neograph::graph::InMemoryCheckpointStore:

Collaboration diagram for neograph::graph::InMemoryCheckpointStore:

Public Member Functions
size_t	blob_count () const
	Number of distinct channel-value blobs currently held (test helper).
void	clear_writes (const std::string &thread_id, const std::string &parent_checkpoint_id) override
	Discard pending writes for a parent checkpoint once its successor super-step has been fully committed.
void	delete_thread (const std::string &thread_id) override
	Delete all checkpoints for a thread.
std::vector< PendingWrite >	get_writes (const std::string &thread_id, const std::string &parent_checkpoint_id) override
	Load all pending writes attached to a parent checkpoint.
std::vector< Checkpoint >	list (const std::string &thread_id, int limit=100) override
	List checkpoints for a thread, ordered by timestamp (newest first).
std::optional< Checkpoint >	load_by_id (const std::string &id) override
	Load a checkpoint by its unique ID.
std::optional< Checkpoint >	load_latest (const std::string &thread_id) override
	Load the most recent checkpoint for a thread.
size_t	pending_writes_count (const std::string &thread_id, const std::string &parent_checkpoint_id) const
	Get the number of pending writes for a parent checkpoint (test helper).
void	put_writes (const std::string &thread_id, const std::string &parent_checkpoint_id, const PendingWrite &write) override
	Record a successful node execution within an in-progress super-step.
void	save (const Checkpoint &cp) override
	Save a checkpoint.
size_t	size () const
	Get the total number of stored checkpoints (test helper).

Detailed Description

In-memory checkpoint store for testing and single-process use.

Stores checkpoints in memory using std::map. Thread-safe via mutex. Not suitable for production use where persistence across restarts is needed.

Incremental storage (channel-blob deduplication)

Channel values are deduplicated internally by (thread_id, channel, version) — every write bumps Channel::version, so the same value at the same version across multiple checkpoints is stored exactly once. In a typical run only one or two channels change per super-step, so a 1000-step session pays roughly (channels + steps) × value_size instead of channels × steps × value_size.

The dedup is purely an internal storage optimization: callers always receive (and pass in) Checkpoints whose channel_values carry full inline data. Engine code, tests, and migration paths are unaffected.

Persistent CheckpointStore implementations are encouraged to apply the same pattern in their own backends (e.g. a (channel, version) → blob table referenced from a (checkpoint_id, channel) → version table) to get the same on-disk savings.

Definition at line 361 of file checkpoint.h.

Member Function Documentation

blob_count()

size_t neograph::graph::InMemoryCheckpointStore::blob_count

(

)

const

Number of distinct channel-value blobs currently held (test helper).

Use this to verify dedup: writing N identical-state checkpoints leaves blob_count() at one entry per channel, not N × channels.

clear_writes()

void neograph::graph::InMemoryCheckpointStore::clear_writes ( const std::string &  , const std::string &    )

overridevirtual

Discard pending writes for a parent checkpoint once its successor super-step has been fully committed.

Called by the engine after the new super-step checkpoint has been durably saved, so pending writes are never cleared while still being the only record of a node's output.

Parameters

thread_id	Thread identifier.
parent_checkpoint_id	Checkpoint whose pending writes to clear.

Reimplemented from neograph::graph::CheckpointStore.

delete_thread()

void neograph::graph::InMemoryCheckpointStore::delete_thread ( const std::string &  thread_id )

overridevirtual

Delete all checkpoints for a thread.

Parameters

thread_id

Thread identifier to delete.

Reimplemented from neograph::graph::CheckpointStore.

get_writes()

std::vector< PendingWrite > neograph::graph::InMemoryCheckpointStore::get_writes ( const std::string &  , const std::string &    )

overridevirtual

Load all pending writes attached to a parent checkpoint.

Called by the engine on resume to skip already-completed tasks. Default implementation returns an empty vector.

Parameters

thread_id	Thread identifier.
parent_checkpoint_id	Checkpoint whose pending writes to load.

Returns

Vector of pending writes, in insertion order.

Reimplemented from neograph::graph::CheckpointStore.

list()

std::vector< Checkpoint > neograph::graph::InMemoryCheckpointStore::list ( const std::string &  thread_id, int  limit = 100  )

overridevirtual

List checkpoints for a thread, ordered by timestamp (newest first).

Parameters

thread_id	Thread identifier.
limit	Maximum number of checkpoints to return (default: 100).

Returns

Vector of checkpoints.

Reimplemented from neograph::graph::CheckpointStore.

load_by_id()

std::optional< Checkpoint > neograph::graph::InMemoryCheckpointStore::load_by_id ( const std::string &  id )

overridevirtual

Load a checkpoint by its unique ID.

Parameters

id	Checkpoint UUID.

Returns

The checkpoint, or std::nullopt if not found.

Reimplemented from neograph::graph::CheckpointStore.

load_latest()

std::optional< Checkpoint > neograph::graph::InMemoryCheckpointStore::load_latest ( const std::string &  thread_id )

overridevirtual

Load the most recent checkpoint for a thread.

Parameters

thread_id

Thread identifier.

Returns

The latest checkpoint, or std::nullopt if none exists.

Reimplemented from neograph::graph::CheckpointStore.

put_writes()

void neograph::graph::InMemoryCheckpointStore::put_writes ( const std::string &  , const std::string &  , const PendingWrite &    )

overridevirtual

Record a successful node execution within an in-progress super-step.

Called by the engine immediately after a node returns successfully and before its writes are applied to the shared GraphState. The parent_checkpoint_id anchors the pending write to the super-step boundary it was produced under.

Default implementation is a no-op so custom stores keep working; such stores fall back to "full super-step replay" on resume.

Parameters

thread_id	Thread identifier.
parent_checkpoint_id	Checkpoint marking the start of the in-progress super-step.
write	The pending write record to persist.

Reimplemented from neograph::graph::CheckpointStore.

save()

void neograph::graph::InMemoryCheckpointStore::save ( const Checkpoint &  cp )

overridevirtual

Save a checkpoint.

Parameters

cp	The checkpoint to persist.

Reimplemented from neograph::graph::CheckpointStore.

size()

size_t neograph::graph::InMemoryCheckpointStore::size

(

)

const

Get the total number of stored checkpoints (test helper).

Returns

Total checkpoint count across all threads.

---

The documentation for this class was generated from the following file:

• include/neograph/graph/checkpoint.h