Crate rusmes_storage

Expand description

Storage abstraction layer for RusMES

This crate provides a unified storage interface for the RusMES mail server, covering mailbox management, message delivery, metadata tracking, and quota enforcement.

§Architecture

The storage layer is composed of three orthogonal trait abstractions:

MailboxStore — Create, rename, delete, subscribe, and list mailboxes per user.
MessageStore — Append, retrieve, copy, flag, search, and delete messages.
MetadataStore — Manage per-user quotas and per-mailbox counters (exists/recent/unseen).

These three stores are obtained from a single StorageBackend factory, which bundles them together and can be shared across protocol handlers (IMAP, JMAP, POP3, SMTP).

§Backends

Backend	Module	Notes
Filesystem / Maildir	`backends::filesystem`	Atomic delivery via `tmp/` → `new/` rename; flag encoding in filenames
AmateRS distributed KV	`backends::amaters`	Mock implementation with circuit-breaker and exponential-backoff retry logic
PostgreSQL	`backends::postgres`	Full connection pool via `sqlx`, full-text search, migrations

§Example — Filesystem backend

use rusmes_storage::{StorageBackend, MailboxStore, MailboxPath};
use rusmes_storage::backends::filesystem::FilesystemBackend;

let backend = FilesystemBackend::new("/var/mail/rusmes");
let mb_store = backend.mailbox_store();

let user: rusmes_proto::Username = "alice@example.com".parse()?;
let path = MailboxPath::new(user, vec!["INBOX".to_string()]);
let id = mb_store.create_mailbox(&path).await?;

let mailbox = mb_store.get_mailbox(&id).await?;
println!("Created: {:?}", mailbox);

§ModSeq (Modification Sequence Numbers)

ModSeqGenerator produces monotonically increasing sequence numbers suitable for IMAP CONDSTORE / QRESYNC extensions. Both mailbox-level and message-level ModSeq values are tracked via MailboxModSeq and MessageModSeq wrappers.

§Metrics

StorageMetrics records per-operation histograms for timing storage calls from higher-level protocol handlers, enabling Prometheus-compatible export.

Re-exports§

pub use backup::backup;
pub use backup::restore;
pub use metrics::Histogram;
pub use metrics::MetricsSummary;
pub use metrics::StorageMetrics;
pub use metrics::StorageTimer;
pub use modseq::MailboxModSeq;
pub use modseq::MessageModSeq;
pub use modseq::ModSeq;
pub use modseq::ModSeqGenerator;

Modules§

backends: Storage backend implementations
backup: Backup and restore library API for rusmes storage backends.
metrics: Storage metrics collection and tracking
modseq: MODSEQ (Modification Sequence) tracking for IMAP CONDSTORE

Structs§

Mailbox: Mailbox metadata
MailboxCounters: Mailbox counters
MailboxId: Unique identifier for a mailbox
MailboxPath: Mailbox path (hierarchical)
MessageFlags: Message flags (IMAP standard flags)
MessageMetadata: Message metadata in a mailbox
Quota: User quota information
SpecialUseAttributes: Special-use mailbox attributes (RFC 6154)

Enums§

BackendKind: Configuration for which storage backend to build.
SearchCriteria: Search criteria for messages
StorageEvent: Events emitted by storage backends after write operations.

Traits§

MailboxStore: Mailbox storage operations
MessageStore: Message storage operations
MetadataStore: Metadata storage operations
StorageBackend: Combined storage backend

Functions§

build_storage: Construct a storage backend from configuration.
compact_expunged: Perform compaction: remove expunged messages older than older_than.