126 lines
3.7 KiB
Rust
126 lines
3.7 KiB
Rust
//! A buffer for reading data from the network.
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//!
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//! The `ReadBuffer` is a buffer of bytes similar to a first-in, first-out queue.
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//! It is filled by reading from a stream supporting `Read` and is then
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//! accessible as a cursor for reading bytes.
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use std::io::{Cursor, Read, Result as IoResult};
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use bytes::Buf;
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/// A FIFO buffer for reading packets from the network.
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#[derive(Debug)]
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pub struct ReadBuffer<const CHUNK_SIZE: usize> {
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storage: Cursor<Vec<u8>>,
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chunk: Box<[u8; CHUNK_SIZE]>,
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}
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impl<const CHUNK_SIZE: usize> ReadBuffer<CHUNK_SIZE> {
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/// Create a new empty input buffer.
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pub fn new() -> Self {
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Self::with_capacity(CHUNK_SIZE)
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}
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/// Create a new empty input buffer with a given `capacity`.
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pub fn with_capacity(capacity: usize) -> Self {
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Self::from_partially_read(Vec::with_capacity(capacity))
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}
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/// Create a input buffer filled with previously read data.
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pub fn from_partially_read(part: Vec<u8>) -> Self {
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Self { storage: Cursor::new(part), chunk: Box::new([0; CHUNK_SIZE]) }
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}
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/// Get a cursor to the data storage.
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pub fn as_cursor(&self) -> &Cursor<Vec<u8>> {
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&self.storage
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}
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/// Get a cursor to the mutable data storage.
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pub fn as_cursor_mut(&mut self) -> &mut Cursor<Vec<u8>> {
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&mut self.storage
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}
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/// Consume the `ReadBuffer` and get the internal storage.
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pub fn into_vec(mut self) -> Vec<u8> {
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// Current implementation of `tungstenite-rs` expects that the `into_vec()` drains
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// the data from the container that has already been read by the cursor.
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self.clean_up();
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// Now we can safely return the internal container.
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self.storage.into_inner()
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}
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/// Read next portion of data from the given input stream.
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pub fn read_from<S: Read>(&mut self, stream: &mut S) -> IoResult<usize> {
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self.clean_up();
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let size = stream.read(&mut *self.chunk)?;
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self.storage.get_mut().extend_from_slice(&self.chunk[..size]);
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Ok(size)
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}
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/// Cleans ups the part of the vector that has been already read by the cursor.
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fn clean_up(&mut self) {
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let pos = self.storage.position() as usize;
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self.storage.get_mut().drain(0..pos).count();
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self.storage.set_position(0);
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}
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}
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impl<const CHUNK_SIZE: usize> Buf for ReadBuffer<CHUNK_SIZE> {
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fn remaining(&self) -> usize {
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Buf::remaining(self.as_cursor())
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}
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fn chunk(&self) -> &[u8] {
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Buf::chunk(self.as_cursor())
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}
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fn advance(&mut self, cnt: usize) {
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Buf::advance(self.as_cursor_mut(), cnt)
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}
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}
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impl<const CHUNK_SIZE: usize> Default for ReadBuffer<CHUNK_SIZE> {
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fn default() -> Self {
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Self::new()
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn simple_reading() {
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let mut input = Cursor::new(b"Hello World!".to_vec());
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let mut buffer = ReadBuffer::<4096>::new();
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let size = buffer.read_from(&mut input).unwrap();
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assert_eq!(size, 12);
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assert_eq!(buffer.chunk(), b"Hello World!");
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}
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#[test]
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fn reading_in_chunks() {
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let mut inp = Cursor::new(b"Hello World!".to_vec());
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let mut buf = ReadBuffer::<4>::new();
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let size = buf.read_from(&mut inp).unwrap();
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assert_eq!(size, 4);
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assert_eq!(buf.chunk(), b"Hell");
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buf.advance(2);
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assert_eq!(buf.chunk(), b"ll");
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assert_eq!(buf.storage.get_mut(), b"Hell");
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let size = buf.read_from(&mut inp).unwrap();
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assert_eq!(size, 4);
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assert_eq!(buf.chunk(), b"llo Wo");
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assert_eq!(buf.storage.get_mut(), b"llo Wo");
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let size = buf.read_from(&mut inp).unwrap();
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assert_eq!(size, 4);
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assert_eq!(buf.chunk(), b"llo World!");
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}
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}
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