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Eliminate looping, message reparsing in codec with take_until #274

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merged 2 commits into from
May 20, 2021
Merged

Eliminate looping, message reparsing in codec with take_until #274

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f08c75e
Eliminate looping, message reparsing in codec with take_until
ebkalderon May 20, 2021
c537596
Improve codec test coverage
ebkalderon May 20, 2021
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80 changes: 55 additions & 25 deletions src/codec.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,9 +10,9 @@ use bytes::buf::BufMut;
use bytes::{Buf, BytesMut};
use log::trace;
use nom::branch::alt;
use nom::bytes::streaming::{is_not, tag};
use nom::bytes::streaming::{is_not, tag, take_until};
use nom::character::streaming::{char, crlf, digit1, space0};
use nom::combinator::{map_res, opt};
use nom::combinator::{map, map_res, opt};
use nom::error::ErrorKind;
use nom::multi::length_data;
use nom::sequence::{delimited, terminated, tuple};
Expand Down Expand Up @@ -145,16 +145,18 @@ impl<T: DeserializeOwned> Decoder for LanguageServerCodec<T> {
}
Err(Err::Error(err)) | Err(Err::Failure(err)) => {
let code = err.code;
loop {
use ParseError::*;
match parse_message(src) {
Err(_) if !src.is_empty() => src.advance(1),
_ => match code {
ErrorKind::Digit | ErrorKind::MapRes => return Err(InvalidLength),
ErrorKind::Char | ErrorKind::IsNot => return Err(InvalidType),
_ => return Err(MissingHeader),
},
}
let parsed_bytes = src.len() - err.input.len();
src.advance(parsed_bytes);

match find_next_message(src) {
Ok((_, position)) => src.advance(position),
Err(_) => src.advance(src.len()),
}

match code {
ErrorKind::Digit | ErrorKind::MapRes => return Err(ParseError::InvalidLength),
ErrorKind::Char | ErrorKind::IsNot => return Err(ParseError::InvalidType),
_ => return Err(ParseError::MissingHeader),
}
}
};
Expand Down Expand Up @@ -193,17 +195,34 @@ fn parse_message(input: &[u8]) -> IResult<&[u8], &[u8]> {
message(input)
}

fn find_next_message(input: &[u8]) -> IResult<&[u8], usize> {
map(take_until("Content-Length"), |s: &[u8]| s.len())(input)
}

#[cfg(test)]
mod tests {
use bytes::BytesMut;
use serde_json::Value;

use super::*;

fn encode_message(content_type: Option<&str>, message: &str) -> String {
let content_type = content_type
.map(|ty| format!("\r\nContent-Type: {}", ty))
.unwrap_or_default();

format!(
"Content-Length: {}{}\r\n\r\n{}",
message.len(),
content_type,
message
)
}

#[test]
fn encode_and_decode() {
let decoded = r#"{"jsonrpc":"2.0","method":"exit"}"#.to_string();
let encoded = format!("Content-Length: {}\r\n\r\n{}", decoded.len(), decoded);
let decoded = r#"{"jsonrpc":"2.0","method":"exit"}"#;
let encoded = encode_message(None, &decoded);

let mut codec = LanguageServerCodec::default();
let mut buffer = BytesMut::new();
Expand All @@ -219,10 +238,9 @@ mod tests {

#[test]
fn decodes_optional_content_type() {
let decoded = r#"{"jsonrpc":"2.0","method":"exit"}"#.to_string();
let content_len = format!("Content-Length: {}", decoded.len());
let content_type = "Content-Type: application/vscode-jsonrpc; charset=utf-8".to_string();
let encoded = format!("{}\r\n{}\r\n\r\n{}", content_len, content_type, decoded);
let decoded = r#"{"jsonrpc":"2.0","method":"exit"}"#;
let content_type = "application/vscode-jsonrpc; charset=utf-8";
let encoded = encode_message(Some(content_type), decoded);

let mut codec = LanguageServerCodec::default();
let mut buffer = BytesMut::from(encoded.as_str());
Expand All @@ -233,8 +251,8 @@ mod tests {

#[test]
fn decodes_zero_length_message() {
let content_type = "Content-Type: application/vscode-jsonrpc; charset=utf-8".to_string();
let encoded = format!("Content-Length: 0\r\n{}\r\n\r\n", content_type);
let content_type = "Content-Type: application/vscode-jsonrpc; charset=utf-8";
let encoded = encode_message(Some(content_type), "");

let mut codec = LanguageServerCodec::default();
let mut buffer = BytesMut::from(encoded.as_str());
Expand All @@ -244,9 +262,9 @@ mod tests {

#[test]
fn recovers_from_parse_error() {
let decoded = r#"{"jsonrpc":"2.0","method":"exit"}"#.to_string();
let encoded = format!("Content-Length: {}\r\n\r\n{}", decoded.len(), decoded);
let mixed = format!("1234567890abcdefgh{}", encoded);
let decoded = r#"{"jsonrpc":"2.0","method":"exit"}"#;
let encoded = encode_message(None, decoded);
let mixed = format!("foobar{}Content-Length: foobar\r\n\r\n{}", encoded, encoded);

let mut codec = LanguageServerCodec::default();
let mut buffer = BytesMut::from(mixed.as_str());
Expand All @@ -256,8 +274,20 @@ mod tests {
other => panic!("expected `Err(ParseError::MissingHeader)`, got {:?}", other),
}

let message: Option<Value> = codec.decode(&mut buffer).unwrap();
let first_valid = serde_json::from_str(&decoded).unwrap();
assert_eq!(message, Some(first_valid));

match codec.decode(&mut buffer) {
Err(ParseError::InvalidLength) => {}
other => panic!("expected `Err(ParseError::InvalidLength)`, got {:?}", other),
}

let message = codec.decode(&mut buffer).unwrap();
let decoded: Value = serde_json::from_str(&decoded).unwrap();
assert_eq!(message, Some(decoded));
let second_valid = serde_json::from_str(&decoded).unwrap();
assert_eq!(message, Some(second_valid));

let message = codec.decode(&mut buffer).unwrap();
assert_eq!(message, None);
}
}