In-Memory Saga Store

• ID: saga.in-memory-store
• Name: In-memory saga store
• Maturity: Extension
• Summary: Thread-safe explicit saga store for unit tests and local development.

What It Does

InMemorySagaStore implements ISagaStore using a concurrent dictionary keyed by a typed tenant, saga definition, and correlation value. The typed key prevents delimiter collisions when identifiers contain colons. State serializes through IMessageSerializer to JSON in memory. Select it explicitly with SagaModuleBuilder.UseInMemoryStorage().

The store enforces the same optimistic concurrency rules as PostgreSQL. A new row requires expected version 0. Updates and completion require an exact version match, and completed rows reject further writes. Completion uses ConcurrentDictionary.TryUpdate, so two callers cannot complete one version successfully. The injected TimeProvider supplies creation and update timestamps used by query ordering and retention purge.

Public Surface

Packages

• LiteBus.Saga

Requires

• saga.store (implements contract)
• saga.inbox-integration (nested composition path)

Invariants

• Process-local only; data is lost on restart.
• Same storage key algorithm as PostgreSQL store via SagaCorrelationKey.
• Query returns most recently updated rows first and rejects Take values less than 1.
• CompletedBefore compares the recorded completion update time, not the current clock at query time.
• Cannot be combined with another storage selection in one saga composition.

Non-Goals

• Not for production multi-instance deployments.
• No schema migration or backup story.

Observability

None.

What to use instead

• Use PostgreSQL store for production multi-instance hosts (saga.postgresql-storage).
• Unit and composition tests assert store outcomes via LoadAsync rather than internal dictionary metrics.

Deep Docs

• README
• store
• postgresql-storage

Test Coverage

Covered Use Cases

SagaProcessorHookTests.ProcessPendingAsync_PersistsSagaStateAfterSuccessfulDispatch

• Use case: Default in-memory store persists state through hook-mediated save.
• Test kind: Unit
• Description: Explicit InMemorySagaStore registered in test service collection.
• Behavior: Hook SaveAsync after handler mutation.
• Expected outcome: Load returns Step == 1.
• Remarks: tests/LiteBus.Storage.UnitTests/Saga/.

SagaProcessorHookTests.AfterDispatch_WhenDirtyAndComplete_ThrowsInvalidOperationException

• Use case: In-memory store not written when hook rejects invalid scope flags.
• Test kind: Unit
• Description: InMemorySagaStore behind hook; exception before save.
• Behavior: Invalid dirty+complete combination.
• Expected outcome: Exception; no row created.
• Remarks: tests/LiteBus.Storage.UnitTests/Saga/.

LiteBusV6CompositionSmokeTests.AddV6CompositionSmoke_ShouldPersistSagaStateAcrossCorrelatedCommands

• Use case: Sample composition explicitly selects the in-memory store for a correlated workflow.
• Test kind: Composition
• Description: AddLiteBusV6 without PostgreSQL saga storage.
• Behavior: Two saves through hook.
• Expected outcome: Step == 2 on load.
• Remarks: tests/LiteBus.Runtime.UnitTests/Runtime/Composition/.

InMemorySagaStoreTests

• Use case: Direct store behavior matches the durable optimistic-concurrency contract.
• Test kind: Unit
• Description: Covers insert and update versions, stale and completed writes, missing and repeated completion, concurrent completion, delimiter-safe identifiers, query ordering, Take validation, timestamps, and CompletedBefore purge.
• Behavior: Store APIs execute against one process-local instance with a controlled clock.
• Expected outcome: Conflicts throw SagaConcurrencyException; query and purge return deterministic results.
• Remarks: tests/LiteBus.Storage.UnitTests/Saga/.

Untested Use Cases

Out-of-Scope Use Cases

• Production multi-instance durability.
• Cross-process or cross-host state sharing.
• Backup and restore semantics.