[router] refactor generate to use new pipeline arch (#11323)

sgl-router/src/routers/grpc/utils.rs

@@ -5,7 +5,7 @@ use crate::core::Worker;
 use crate::grpc_client::{proto, SglangSchedulerClient};
 use crate::protocols::spec::{
     ChatCompletionRequest, ChatLogProbs, ChatLogProbsContent, ChatMessage, FunctionCallResponse,
-    StringOrArray, Tool, ToolCall, ToolChoice, ToolChoiceValue, TopLogProb,
+    GenerateFinishReason, StringOrArray, Tool, ToolCall, ToolChoice, ToolChoiceValue, TopLogProb,
 };
 use crate::tokenizer::chat_template::{ChatTemplateContentFormat, ChatTemplateParams};
 use crate::tokenizer::traits::Tokenizer;
@@ -809,6 +809,70 @@ pub fn convert_proto_to_openai_logprobs(
     })
 }
 
+/// Convert proto::OutputLogProbs to Generate format Vec<Vec<Option<f64>>>
+///
+/// Generate format: [[logprob, token_id, ...], [logprob, token_id, ...], ...]
+/// Each inner vec contains [logprob (f64), token_id (i32), ...]
+pub fn convert_generate_output_logprobs(
+    proto_logprobs: &proto::OutputLogProbs,
+) -> Vec<Vec<Option<f64>>> {
+    proto_logprobs
+        .token_logprobs
+        .iter()
+        .zip(proto_logprobs.token_ids.iter())
+        .map(|(&logprob, &token_id)| vec![Some(logprob as f64), Some(token_id as f64)])
+        .collect()
+}
+
+/// Convert proto::InputLogProbs to Generate format Vec<Vec<Option<f64>>>
+///
+/// Generate format: [[logprob, token_id, ...], [logprob, token_id, ...], ...]
+/// First token has null logprob: [[null, token_id], [logprob, token_id], ...]
+pub fn convert_generate_input_logprobs(
+    proto_logprobs: &proto::InputLogProbs,
+) -> Vec<Vec<Option<f64>>> {
+    proto_logprobs
+        .token_logprobs
+        .iter()
+        .zip(proto_logprobs.token_ids.iter())
+        .map(|(token_logprob, &token_id)| {
+            // InputTokenLogProb has optional value field
+            let logprob_value = token_logprob.value.map(|v| v as f64);
+            vec![logprob_value, Some(token_id as f64)]
+        })
+        .collect()
+}
+
+/// Parse finish_reason string into GenerateFinishReason enum
+///
+/// Uses serde to deserialize the finish_reason, which handles all tagged variants automatically.
+/// The GenerateFinishReason enum is tagged with `#[serde(tag = "type", rename_all = "lowercase")]`,
+/// so it expects JSON objects like:
+/// - `{"type":"stop"}` -> Stop
+/// - `{"type":"length","length":100}` -> Length { length: 100 }
+/// - Any other JSON -> Other(...)
+///
+/// For backward compatibility, also handles simple string "stop" -> Stop
+pub fn parse_finish_reason(reason_str: &str, completion_tokens: i32) -> GenerateFinishReason {
+    if reason_str == "stop" {
+        return GenerateFinishReason::Stop;
+    }
+
+    if reason_str == "length" {
+        return GenerateFinishReason::Length {
+            length: completion_tokens.max(0) as u32,
+        };
+    }
+
+    match serde_json::from_str::<GenerateFinishReason>(reason_str) {
+        Ok(finish_reason) => finish_reason,
+        Err(_) => match serde_json::from_str::<Value>(reason_str) {
+            Ok(json_value) => GenerateFinishReason::Other(json_value),
+            Err(_) => GenerateFinishReason::Other(Value::String(reason_str.to_string())),
+        },
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;