Crate photon_backend 

Transport log, storage adapters, and delivery for Photon.

Pluggable StoragePort implementations, unified GenericPhotonBackend, subscriptions, checkpoints, retention, and consumer groups.

Goals

• Append-only sequenced transport with swappable storage adapters (mem, sqlite, broker tiers)
• Durable subscriptions with coalesced checkpoints and optional retention reclaim
• Consumer-group shard routing for load-balanced handlers

Non-goals

• Canonical system-of-record datastore (transport log is encrypted and transient)
• Ops/admin UI (hosts provide their own)

Facade documentation map: cargo doc -p uf-photon --features runtime,mem --open.

Re-exports

pub use backend::BackendCapabilities;

pub use backend::BackendContext;

pub use backend::EmbeddedBackend;

pub use backend::GenericPhotonBackend;

pub use backend::PhotonBackend;

pub use consumer_group::ConsumerGroupCoordinator;

pub use consumer_group::ConsumerLease;

pub use consumer_group::FleetGroupCoordinator;

pub use consumer_group::GroupMember;

pub use consumer_group::LeaseStore;

pub use consumer_group::MemoryLeaseStore;

pub use consumer_group::StaticGroupCoordinator;

pub use delivery_mode::DeliveryMode;

pub use delivery_mode::ShardConfig;

pub use descriptor::TopicDescriptor;

pub use error::PhotonError;

pub use error::Result;

pub use event::TransportCrypto;

pub use executor_services::ExecutorServices;

pub use group_subscribe::merge_shard_streams;

pub use handler_ctx::HandlerCtx;

pub use handler_descriptor::HandlerDescriptor;

pub use handler_registry::HandlerRegistry;

pub use publish_routing::resolve_publish_target;

pub use publish_routing::PublishTarget;

pub use shard_router::group_publish_storage_key;

pub use shard_router::is_shard_storage_key;

pub use shard_router::parse_shard_storage_key;

pub use shard_router::routing_key;

pub use shard_router::shard_id;

pub use shard_router::shard_storage_key;

pub use shard_router::SHARD_KEY_PREFIX;

pub use models::Envelope;

pub use models::Event;

pub use models::GroupOpts;

pub use models::SubscribeOpts;

pub use models::Subscription;

pub use models::SubscriptionHandle;

pub use models::SubscriptionMode;

pub use models::TopicMetadata;

pub use registry::TopicRegistry;

pub use retention::ReclaimReport;

pub use retention::RetentionDeps;

pub use retention::RetentionHook;

pub use retention::RetentionPolicy;

pub use retention::RetentionReclaimer;

pub use retention::SubscriptionPartition;

pub use retention::TopicPartition;

pub use storage::InProcStoragePort;

pub use storage::StorageCapabilities;

pub use storage::StoragePort;

pub use storage::topic_filter_matches;

pub use quark::inventory;

Modules

backend

Backend implementations and assembly context for Photon.

checkpoint

Checkpoint coalescing for durable subscriptions.

consumer_group

Consumer group coordination: shard assignment and leases.

delivery

Handler delivery: backpressure and dead-letter queue.

delivery_mode

Topic delivery mode and virtual shard configuration.

descriptor

Topic descriptor for auto-registration.

error

Error types for Photon.

event

Event envelope encryption.

executor_services

Shared runtime services for handler delivery (constructed at Photon build time).

group_subscribe

Multiplex assigned virtual shard streams for consumer-group subscribers.

handler_ctx

Delivery metadata injectable into #[photon::subscribe] handlers (v2).

handler_descriptor

Handler descriptor for #[photon::subscribe] inventory registration.

handler_registry

Registry of #[photon::subscribe] handlers discovered via inventory.

instrumentation

Backend instrumentation (L0 publish telemetry + ops log helpers).

models

In-memory models for Photon entities.

publish_routing

Resolve storage keys for publishes based on topic delivery mode.

registry

Topic registry for discovering and looking up registered topics.

retention

Integrated transport retention / reclaim workflow.

shard_router

Virtual shard routing for consumer-group topics.

storage

Storage adapter port — one implementation per --storage tier (mem, sqlite, nats, fluvio, kafka).