bigrag 0.1.1

Rust client for bigRAG — a self-hostable RAG platform
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139

use std::collections::VecDeque;
use std::pin::Pin;
use std::task::{Context, Poll};

use futures_core::Stream;

use crate::error::BigRagError;
use crate::types::sse::ProgressEvent;

/// Incrementally parses SSE text into `ProgressEvent` values.
pub(crate) struct SseParser {
    buffer: String,
}

impl SseParser {
    pub fn new() -> Self {
        Self {
            buffer: String::new(),
        }
    }

    /// Push a chunk of text and return any complete events found.
    pub fn push(&mut self, text: &str) -> Vec<ProgressEvent> {
        self.buffer.push_str(text);
        let mut events = Vec::new();

        while let Some(pos) = self.buffer.find("\n\n") {
            let block = self.buffer[..pos].to_string();
            self.buffer = self.buffer[pos + 2..].to_string();

            for line in block.lines() {
                if let Some(json_str) = line.strip_prefix("data: ") {
                    if let Ok(event) = serde_json::from_str::<ProgressEvent>(json_str) {
                        events.push(event);
                    }
                }
                // Skip comments (": heartbeat") and other lines
            }
        }

        events
    }
}

/// A stream of SSE progress events from the bigRAG API.
///
/// Implements `futures_core::Stream<Item = Result<ProgressEvent, BigRagError>>`.
/// Consume with `StreamExt::next()` from `futures-util` or `tokio-stream`.
pub struct SseStream {
    inner: Pin<Box<dyn Stream<Item = Result<bytes::Bytes, reqwest::Error>> + Send>>,
    parser: SseParser,
    pending: VecDeque<ProgressEvent>,
}

impl SseStream {
    /// Create an SSE stream from a raw reqwest response.
    pub(crate) fn new(response: reqwest::Response) -> Self {
        Self {
            inner: Box::pin(response.bytes_stream()),
            parser: SseParser::new(),
            pending: VecDeque::new(),
        }
    }
}

impl Stream for SseStream {
    type Item = Result<ProgressEvent, BigRagError>;

    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
        // Yield any buffered events first.
        if let Some(event) = self.pending.pop_front() {
            return Poll::Ready(Some(Ok(event)));
        }

        // Try to read more data from the byte stream.
        match self.inner.as_mut().poll_next(cx) {
            Poll::Ready(Some(Ok(chunk))) => {
                let text = String::from_utf8_lossy(&chunk);
                let mut events: VecDeque<_> = self.parser.push(&text).into();

                if let Some(first) = events.pop_front() {
                    self.pending = events;
                    Poll::Ready(Some(Ok(first)))
                } else {
                    // Got data but no complete event yet, wake and retry.
                    cx.waker().wake_by_ref();
                    Poll::Pending
                }
            }
            Poll::Ready(Some(Err(e))) => {
                Poll::Ready(Some(Err(BigRagError::Connection(e.to_string()))))
            }
            Poll::Ready(None) => Poll::Ready(None), // Stream ended.
            Poll::Pending => Poll::Pending,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_parse_sse_lines_data() {
        let mut parser = SseParser::new();
        let events =
            parser.push("data: {\"step\":\"chunking\",\"message\":\"ok\",\"progress\":50.0}\n\n");
        assert_eq!(events.len(), 1);
        assert_eq!(events[0].step, "chunking");
        assert_eq!(events[0].progress, 50.0);
    }

    #[test]
    fn test_parse_sse_lines_skips_heartbeat() {
        let mut parser = SseParser::new();
        let events = parser.push(": heartbeat\n\n");
        assert_eq!(events.len(), 0);
    }

    #[test]
    fn test_parse_sse_lines_handles_partial() {
        let mut parser = SseParser::new();
        let events = parser.push("data: {\"step\":\"chunk");
        assert_eq!(events.len(), 0);
        let events = parser.push("ing\",\"message\":\"ok\",\"progress\":50.0}\n\n");
        assert_eq!(events.len(), 1);
        assert_eq!(events[0].step, "chunking");
    }

    #[test]
    fn test_parse_sse_lines_multiple_events() {
        let mut parser = SseParser::new();
        let input = "data: {\"step\":\"a\",\"message\":\"\",\"progress\":0.0}\n\ndata: {\"step\":\"b\",\"message\":\"\",\"progress\":100.0}\n\n";
        let events = parser.push(input);
        assert_eq!(events.len(), 2);
        assert_eq!(events[0].step, "a");
        assert_eq!(events[1].step, "b");
    }
}