Redis Compatibility Protocol

we-trust-redis implements the Redis Serialization Protocol (RESP), allowing YYKV to serve as a high-performance, persistent alternative to Redis.

1. Protocol Core: RESP

YYKV fully supports various data types of RESP (REdis Serialization Protocol):

Simple Strings: Starts with +, e.g., +OK\r\n.
Errors: Starts with -, includes error type.
Integers: Starts with :.
Bulk Strings: Starts with $, binary-safe.
Arrays: Starts with *, supports nested structures.

2. Command Mapping Logic

The Redis compatibility layer employs a dynamic mapping engine that converts common KV operations directly into YYKV native atomic instructions, bypassing SQL parsing overhead.

Redis Command	YYKV Native Operation	Performance
`SET`	`MessageType::Put`	$O(1)$, direct write to WAL and MemTable
`GET`	`MessageType::Get`	$O(1)$, supports cache hit optimization
`DEL`	`MessageType::Delete`	$O(1)$, writes a deletion marker (Tombstone)
`KEYS`	`MessageType::Scan`	$O(N)$, utilizes prefix scanning optimization

3. Architecture & Execution Flow

The following diagram shows how a Redis command is processed within the YYKV kernel:

sequenceDiagram
    Client->>we-trust-redis: RESP3 Command (e.g. SET)
    we-trust-redis->>yykv-operators: Translate to OpsGraph
    yykv-operators->>yykv-executor: Execute Task
    yykv-executor->>yykv-event: WAE Event Write
    yykv-event->>Disk: Direct IO Persistence
    yykv-executor-->>we-trust-redis: Success
    we-trust-redis-->>Client: +OK

4. Persistence & Consistency

Unlike standard Redis AOF/RDB, YYKV provides database-grade persistence guarantees for the Redis protocol:

WAL Strong Sync: Ensures logs are flushed to disk before returning from a SET operation.
Multi-Level Tiering: Hot data stays in Memory/SSD, while cold data automatically migrates to HDD, breaking the memory capacity limit of Redis.

5. Multi-Tenant Extensions

YYKV provides non-destructive extensions to the Redis protocol:

Tenant Prefixing: Internal physical isolation via Tenant IDs, transparent to the client.
Enhanced AUTH: Supports fine-grained tenant-level authentication via AUTH <tenant_id> <password>.

6. Performance Advantages

Zero-Copy Path: Leverages the bytes crate to directly mount data from network buffers into the storage engine, avoiding frequent sds string copies internal to Redis.
Multi-Core Concurrency: Powered by Rust's tokio scheduler, YYKV fully utilizes multi-core CPUs to handle Redis requests, overcoming the bottleneck of the single-threaded Redis model.