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Merge pull request #74 from ikatson/small-refactor
Small refactor - introduce ReadBuf
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,96 @@ | ||
| use std::time::Duration; | ||
|
|
||
| use crate::peer_connection::with_timeout; | ||
| use anyhow::Context; | ||
| use buffers::ByteBuf; | ||
| use peer_binary_protocol::{ | ||
| Handshake, MessageBorrowed, MessageDeserializeError, PIECE_MESSAGE_DEFAULT_LEN, | ||
| }; | ||
| use tokio::io::AsyncReadExt; | ||
|
|
||
| pub struct ReadBuf { | ||
| buf: Vec<u8>, | ||
| // How many bytes into the buffer we have read from the connection. | ||
| // New reads should go past this. | ||
| filled: usize, | ||
| // How many bytes have we successfully deserialized. | ||
| processed: usize, | ||
| } | ||
|
|
||
| impl ReadBuf { | ||
| pub fn new() -> Self { | ||
| Self { | ||
| buf: vec![0; PIECE_MESSAGE_DEFAULT_LEN * 2], | ||
| filled: 0, | ||
| processed: 0, | ||
| } | ||
| } | ||
|
|
||
| fn prepare_for_read(&mut self, need_additional_bytes: usize) { | ||
| // Ensure the buffer starts from the to-be-deserialized message. | ||
| if self.processed > 0 { | ||
| if self.filled > self.processed { | ||
| self.buf.copy_within(self.processed..self.filled, 0); | ||
| } | ||
| self.filled -= self.processed; | ||
| self.processed = 0; | ||
| } | ||
|
|
||
| // Ensure we have enough capacity to deserialize the message. | ||
| if self.buf.len() < self.filled + need_additional_bytes { | ||
| self.buf.reserve(need_additional_bytes); | ||
| self.buf.resize(self.buf.capacity(), 0); | ||
| } | ||
| } | ||
|
|
||
| // Read the BT handshake. | ||
| // This MUST be run as the first operation on the buffer. | ||
| pub async fn read_handshake( | ||
| &mut self, | ||
| mut conn: impl AsyncReadExt + Unpin, | ||
| timeout: Duration, | ||
| ) -> anyhow::Result<Handshake<ByteBuf<'_>>> { | ||
| self.filled = with_timeout(timeout, conn.read(&mut self.buf)) | ||
| .await | ||
| .context("error reading handshake")?; | ||
| if self.filled == 0 { | ||
| anyhow::bail!("peer disconnected while reading handshake"); | ||
| } | ||
| let (h, size) = Handshake::deserialize(&self.buf[..self.filled]) | ||
| .map_err(|e| anyhow::anyhow!("error deserializing handshake: {:?}", e))?; | ||
| self.processed = size; | ||
| Ok(h) | ||
| } | ||
|
|
||
| // Read a message into the buffer, try to deserialize it and call the callback on it. | ||
| // We can't return the message because of a borrow checker issue. | ||
| pub async fn read_message( | ||
| &mut self, | ||
| mut conn: impl AsyncReadExt + Unpin, | ||
| timeout: Duration, | ||
| on_message: impl for<'a> FnOnce(MessageBorrowed<'a>) -> anyhow::Result<()>, | ||
| ) -> anyhow::Result<()> { | ||
| loop { | ||
| let need_additional_bytes = | ||
| match MessageBorrowed::deserialize(&self.buf[self.processed..self.filled]) { | ||
| Err(MessageDeserializeError::NotEnoughData(d, _)) => d, | ||
| Ok((msg, size)) => { | ||
| self.processed += size; | ||
| // Rust's borrow checker can't do this early return. So we are using a callback instead. | ||
| // return Ok(msg); | ||
| on_message(msg)?; | ||
| return Ok(()); | ||
| } | ||
| Err(e) => return Err(e.into()), | ||
| }; | ||
| self.prepare_for_read(need_additional_bytes); | ||
| let size = with_timeout(timeout, conn.read(&mut self.buf[self.filled..])) | ||
| .await | ||
| .context("error reading from peer")?; | ||
| if size == 0 { | ||
| anyhow::bail!("disconnected while reading, read so far: {}", self.filled) | ||
| } | ||
| self.filled += size; | ||
| } | ||
| } | ||
| } |
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