refactor(tlv): decode and encode piece wire layouts with zerocopy structs

Cargo.toml

@@ -1,19 +1,21 @@
 [package]
 name = "vortex-protocol"
-version = "0.1.5"
+version = "0.2.0"
 description = "A P2P file transfer protocol"
 authors = ["The Dragonfly Developers"]
 homepage = "https://d7y.io/"
-repository = "https://github.com/dragonflyoss/vortex.git"
+repository = "https://github.com/dragonflyoss/vortex-protocol.git"
 keywords = ["dragonfly", "p2p"]
 license = "Apache-2.0"
 readme = "README.md"
 edition = "2021"
+rust-version = "1.80"
 
 [dependencies]
 thiserror = "2.0"
 rand = "0.8"
 bytes = "1"
+zerocopy = { version = "0.8", features = ["derive"] }
 chrono = { version = "0.4.44", features = ["serde", "clock"] }
 
 [dev-dependencies]

README.md

@@ -17,18 +17,41 @@ efficient and flexible data transmission, making it ideal for large-scale file d
 - **High Performance**: Designed for high-throughput file transfer scenarios.
 - **Extensible Design**: Reserved tags for future protocol extensions like compression and encryption.
 
+## Usage
+
+Every TLV value implements `Message`, which encodes into any `BufMut` and decodes from a byte
+slice. `encode_packet` prepends the packet header; `Vortex::decode` parses a whole packet.
+
+```rust
+use bytes::BytesMut;
+use vortex_protocol::tlv::download_piece::DownloadPiece;
+use vortex_protocol::{Message, Vortex, HEADER_SIZE};
+
+let request = DownloadPiece::new("a".repeat(64), 1);
+let mut buffer = BytesMut::with_capacity(HEADER_SIZE + request.encoded_len());
+request.encode_packet(&mut buffer);
+
+match Vortex::decode(&buffer)? {
+    Vortex::DownloadPiece(header, request) => println!("{} {:?}", header.length(), request),
+    packet => println!("unexpected packet {packet:?}"),
+}
+```
+
+The wire format is stable across releases: peers running different versions of the crate
+interoperate, and `tests/wire_format.rs` pins the bytes produced by earlier releases.
+
 ## Documentation
 
 For details, please see [the specification](docs/README.md).
 
 ## Benchmarking
 
-Vortex protocol includes comprehensive benchmarks for packet creation, serialization, and deserialization:
+Vortex protocol includes benchmarks for encoding and decoding every message and whole packets:
 
 ```bash
 # Run all benchmarks
 cargo bench
 
-# Run specific benchmark group
-cargo bench "Vortex Packet Creation"
+# Run the benchmarks of one message
+cargo bench PieceContent
 ```