[bugfix] Fix logprobs on meta-reference impl (#213)

* fix log probs

* add back LogProbsConfig

* error handling

* bugfix

llama_stack/apis/inference/client.py

@@ -6,7 +6,6 @@
 
 import asyncio
 import json
-import sys
 from typing import Any, AsyncGenerator, List, Optional
 
 import fire
@@ -101,7 +100,9 @@ class InferenceClient(Inference):
                             print(f"Error with parsing or validation: {e}")
 
 
-async def run_main(host: str, port: int, stream: bool, model: Optional[str]):
+async def run_main(
+    host: str, port: int, stream: bool, model: Optional[str], logprobs: bool
+):
     client = InferenceClient(f"http://{host}:{port}")
 
     if not model:
@@ -111,13 +112,27 @@ async def run_main(host: str, port: int, stream: bool, model: Optional[str]):
         content="hello world, write me a 2 sentence poem about the moon"
     )
     cprint(f"User>{message.content}", "green")
+
+    if logprobs:
+        logprobs_config = LogProbConfig(
+            top_k=1,
+        )
+    else:
+        logprobs_config = None
+
     iterator = client.chat_completion(
         model=model,
         messages=[message],
         stream=stream,
+        logprobs=logprobs_config,
     )
-    async for log in EventLogger().log(iterator):
-        log.print()
+
+    if logprobs:
+        async for chunk in iterator:
+            cprint(f"Response: {chunk}", "red")
+    else:
+        async for log in EventLogger().log(iterator):
+            log.print()
 
 
 async def run_mm_main(
@@ -149,13 +164,14 @@ def main(
     port: int,
     stream: bool = True,
     mm: bool = False,
+    logprobs: bool = False,
     file: Optional[str] = None,
     model: Optional[str] = None,
 ):
     if mm:
         asyncio.run(run_mm_main(host, port, stream, file, model))
     else:
-        asyncio.run(run_main(host, port, stream, model))
+        asyncio.run(run_main(host, port, stream, model, logprobs))
 
 
 if __name__ == "__main__":

llama_stack/providers/impls/meta_reference/inference/generation.py

@@ -297,7 +297,7 @@ class Llama:
                 token=next_token[0].item(),
                 text=self.tokenizer.decode(next_token.tolist()),
                 logprobs=(
-                    token_logprobs[:, prev_pos + 1 : cur_pos + 1][0].tolist()
+                    token_logprobs[:, cur_pos : cur_pos + 1][0].tolist()
                     if logprobs
                     else None
                 ),

llama_stack/providers/impls/meta_reference/inference/inference.py

@@ -132,7 +132,20 @@ class MetaReferenceInferenceImpl(Inference, RoutableProvider):
 
                 if not request.stream:
                     if request.logprobs:
-                        logprobs.append(token_result.logprob)
+                        assert (
+                            len(token_result.logprobs) == 1
+                        ), "Expected logprob to contain 1 result for the current token"
+                        assert (
+                            request.logprobs.top_k == 1
+                        ), "Only top_k=1 is supported for LogProbConfig"
+
+                        logprobs.append(
+                            TokenLogProbs(
+                                logprobs_by_token={
+                                    token_result.text: token_result.logprobs[0]
+                                }
+                            )
+                        )
 
                     continue