lc_callbacks/tracing/
span.rs

1use chrono::Utc;
2use serde::{Deserialize, Serialize};
3
4/// Unique span identifier.
5pub type SpanId = String;
6
7/// Kind of span for categorization.
8#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
9#[serde(rename_all = "snake_case")]
10pub enum SpanKind {
11    /// LLM inference call
12    Llm,
13    /// Chain execution
14    Chain,
15    /// Tool invocation
16    Tool,
17    /// Retriever query
18    Retriever,
19    /// Agent execution
20    Agent,
21    /// Custom span kind
22    Custom(String),
23}
24
25impl std::fmt::Display for SpanKind {
26    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
27        match self {
28            SpanKind::Llm => write!(f, "llm"),
29            SpanKind::Chain => write!(f, "chain"),
30            SpanKind::Tool => write!(f, "tool"),
31            SpanKind::Retriever => write!(f, "retriever"),
32            SpanKind::Agent => write!(f, "agent"),
33            SpanKind::Custom(name) => write!(f, "custom:{}", name),
34        }
35    }
36}
37
38/// Token usage recorded in a span.
39#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
40pub struct SpanTokenUsage {
41    pub prompt_tokens: usize,
42    pub completion_tokens: usize,
43    pub total_tokens: usize,
44}
45
46/// Status of a span.
47#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
48#[serde(rename_all = "snake_case")]
49pub enum SpanStatus {
50    /// Span completed successfully
51    Ok,
52    /// Span ended with an error
53    Error(String),
54}
55
56/// A single trace span with parent-child relationships.
57#[derive(Debug, Clone, Serialize, Deserialize)]
58pub struct TraceSpan {
59    /// Unique span identifier
60    pub id: SpanId,
61    /// Parent span ID (None for root spans)
62    pub parent_id: Option<SpanId>,
63    /// Human-readable span name
64    pub name: String,
65    /// Span category
66    pub kind: SpanKind,
67    /// ISO 8601 start time
68    pub start_time: Option<String>,
69    /// ISO 8601 end time
70    pub end_time: Option<String>,
71    /// Token usage (for LLM spans)
72    pub tokens: Option<SpanTokenUsage>,
73    /// Estimated cost in USD
74    pub cost: Option<f64>,
75    /// Measured latency in milliseconds
76    pub latency_ms: Option<u64>,
77    /// Arbitrary key-value metadata
78    pub metadata: serde_json::Value,
79    /// Span completion status
80    pub status: SpanStatus,
81
82    // --- OTel GenAI SemConv fields ---
83    /// gen_ai.system: The LLM provider name (e.g., "openai", "anthropic")
84    #[serde(skip_serializing_if = "Option::is_none")]
85    pub gen_ai_system: Option<String>,
86    /// gen_ai.request.model: The model requested
87    #[serde(skip_serializing_if = "Option::is_none")]
88    pub gen_ai_request_model: Option<String>,
89    /// gen_ai.response.model: The actual model used
90    #[serde(skip_serializing_if = "Option::is_none")]
91    pub gen_ai_response_model: Option<String>,
92    /// gen_ai.response.finish_reason: Why the model stopped generating
93    #[serde(skip_serializing_if = "Option::is_none")]
94    pub gen_ai_finish_reason: Option<String>,
95    /// gen_ai.request.max_tokens: Maximum tokens requested
96    #[serde(skip_serializing_if = "Option::is_none")]
97    pub gen_ai_request_max_tokens: Option<u64>,
98    /// gen_ai.request.temperature: Temperature parameter
99    #[serde(skip_serializing_if = "Option::is_none")]
100    pub gen_ai_request_temperature: Option<f64>,
101    /// gen_ai.operation.name: The operation name (chat, completion)
102    #[serde(skip_serializing_if = "Option::is_none")]
103    pub gen_ai_operation_name: Option<String>,
104    /// gen_ai.tool.name: The tool name (for tool spans)
105    #[serde(skip_serializing_if = "Option::is_none")]
106    pub gen_ai_tool_name: Option<String>,
107}
108
109/// A node in the trace tree (span + children).
110#[derive(Debug, Clone, Serialize, Deserialize)]
111pub struct TraceNode {
112    pub span: TraceSpan,
113    pub children: Vec<TraceNode>,
114}
115
116pub(crate) fn build_tree(root: &TraceSpan, all_spans: &[TraceSpan]) -> TraceNode {
117    let children: Vec<TraceNode> = all_spans
118        .iter()
119        .filter(|s| s.parent_id.as_deref() == Some(root.id.as_str()))
120        .map(|child| build_tree(child, all_spans))
121        .collect();
122
123    TraceNode {
124        span: root.clone(),
125        children,
126    }
127}
128
129/// Helper to create a new span with common defaults.
130pub(crate) fn make_span(
131    id: String,
132    parent_id: Option<SpanId>,
133    name: &str,
134    kind: SpanKind,
135) -> TraceSpan {
136    TraceSpan {
137        id,
138        parent_id,
139        name: name.to_string(),
140        kind,
141        start_time: Some(Utc::now().to_rfc3339()),
142        end_time: None,
143        tokens: None,
144        cost: None,
145        latency_ms: None,
146        metadata: serde_json::Value::Object(serde_json::Map::new()),
147        status: SpanStatus::Ok,
148        gen_ai_system: None,
149        gen_ai_request_model: None,
150        gen_ai_response_model: None,
151        gen_ai_finish_reason: None,
152        gen_ai_request_max_tokens: None,
153        gen_ai_request_temperature: None,
154        gen_ai_operation_name: None,
155        gen_ai_tool_name: None,
156    }
157}
lc_callbacks/tracing/span.rs

lc_callbacks/tracing/
span.rs
