feat(vlm): add num_tokens as attribtue for VlmPrediction (#2489)

* feat: add num_tokens as attribtue for VlmPrediction

* feat: implement tokens tracking for api_vlm

Signed-off-by: Peter El Hachem <peter.el.hachem@ibm.com>

* DCO Remediation Commit for ElHachem02 <peterelhachem02@gmail.com>

I, ElHachem02 <peterelhachem02@gmail.com>, hereby add my Signed-off-by to this commit: 311287f562

Signed-off-by: Peter El Hachem <peter.el.hachem@ibm.com>

* DCO Remediation Commit for ElHachem02 <peterelhachem02@gmail.com>

I, ElHachem02 <peterelhachem02@gmail.com>, hereby add my Signed-off-by to this commit: 311287f562

Signed-off-by: ElHachem02 <peterelhachem02@gmail.com>

* update return type

Signed-off-by: ElHachem02 <peterelhachem02@gmail.com>

* add time recorder for vlm inference and track generated token ids depending on config

Signed-off-by: ElHachem02 <peterelhachem02@gmail.com>

* update num_tokens to have None as value on exception

Signed-off-by: ElHachem02 <peterelhachem02@gmail.com>

* set default value of num_tokens to None

Signed-off-by: ElHachem02 <peterelhachem02@gmail.com>

---------

Signed-off-by: Peter El Hachem <peter.el.hachem@ibm.com>
Signed-off-by: ElHachem02 <peterelhachem02@gmail.com>
Signed-off-by: peets <100425207+ElHachem02@users.noreply.github.com>
Co-authored-by: Peter El Hachem <peter.el.hachem@ibm.com>

docling/datamodel/base_models.py

@@ -207,6 +207,8 @@ class VlmPrediction(BaseModel):
     text: str = ""
     generated_tokens: list[VlmPredictionToken] = []
     generation_time: float = -1
+    num_tokens: Optional[int] = None
+    stop_reason: Optional[str] = None  # todo define an enum for possible stop reasons
 
 
 class ContainerElement(

docling/datamodel/pipeline_options_vlm_model.py

@@ -82,6 +82,7 @@ class InlineVlmOptions(BaseVlmOptions):
 
     use_kv_cache: bool = True
     max_new_tokens: int = 4096
+    track_generated_tokens: bool = False
 
     @property
     def repo_cache_folder(self) -> str:

docling/models/api_vlm_model.py

@@ -73,7 +73,7 @@ class ApiVlmModel(BasePageModel):
                         # Skip non-GenerationStopper criteria (should have been caught in validation)
 
                     # Streaming path with early abort support
-                    page_tags = api_image_request_streaming(
+                    page_tags, num_tokens = api_image_request_streaming(
                         image=hi_res_image,
                         prompt=prompt,
                         url=self.vlm_options.url,
@@ -84,7 +84,7 @@ class ApiVlmModel(BasePageModel):
                     )
                 else:
                     # Non-streaming fallback (existing behavior)
-                    page_tags = api_image_request(
+                    page_tags, num_tokens = api_image_request(
                         image=hi_res_image,
                         prompt=prompt,
                         url=self.vlm_options.url,
@@ -94,7 +94,9 @@ class ApiVlmModel(BasePageModel):
                     )
 
                 page_tags = self.vlm_options.decode_response(page_tags)
-                page.predictions.vlm_response = VlmPrediction(text=page_tags)
+                page.predictions.vlm_response = VlmPrediction(
+                    text=page_tags, num_tokens=num_tokens
+                )
             return page
 
         with ThreadPoolExecutor(max_workers=self.concurrency) as executor:

docling/models/vlm_models_inline/hf_transformers_model.py

@@ -367,13 +367,19 @@ class HuggingFaceTransformersVlmModel(BaseVlmPageModel, HuggingFaceModelDownload
             decoded_texts = [text.rstrip(pad_token) for text in decoded_texts]
 
         # -- Optional logging
+        num_tokens = None
         if generated_ids.shape[0] > 0:
+            num_tokens = int(generated_ids[0].shape[0])
             _log.debug(
-                f"Generated {int(generated_ids[0].shape[0])} tokens in {generation_time:.2f}s "
+                f"Generated {num_tokens} tokens in {generation_time:.2f}s "
                 f"for batch size {generated_ids.shape[0]}."
             )
 
         for text in decoded_texts:
             # Apply decode_response to the output text
             decoded_text = self.vlm_options.decode_response(text)
-            yield VlmPrediction(text=decoded_text, generation_time=generation_time)
+            yield VlmPrediction(
+                text=decoded_text,
+                generation_time=generation_time,
+                num_tokens=num_tokens,
+            )

docling/models/vlm_models_inline/mlx_model.py

@@ -318,5 +318,6 @@ class HuggingFaceMlxModel(BaseVlmPageModel, HuggingFaceModelDownloadMixin):
                     text=decoded_output,
                     generation_time=generation_time,
                     generated_tokens=tokens,
+                    num_tokens=len(tokens),
                 )
             _log.debug("MLX model: Released global lock")

docling/models/vlm_models_inline/nuextract_transformers_model.py

@@ -282,13 +282,19 @@ class NuExtractTransformersModel(BaseVlmModel, HuggingFaceModelDownloadMixin):
         )
 
         # Optional logging
+        num_tokens = None
         if generated_ids.shape[0] > 0:  # type: ignore
+            num_tokens = int(generated_ids[0].shape[0])
             _log.debug(
-                f"Generated {int(generated_ids[0].shape[0])} tokens in {generation_time:.2f}s "
+                f"Generated {num_tokens} tokens in {generation_time:.2f}s "
                 f"for batch size {generated_ids.shape[0]}."  # type: ignore
             )
 
         for text in decoded_texts:
             # Apply decode_response to the output text
             decoded_text = self.vlm_options.decode_response(text)
-            yield VlmPrediction(text=decoded_text, generation_time=generation_time)
+            yield VlmPrediction(
+                text=decoded_text,
+                generation_time=generation_time,
+                num_tokens=num_tokens,
+            )

docling/models/vlm_models_inline/vllm_model.py

@@ -9,7 +9,7 @@ import numpy as np
 from PIL.Image import Image
 
 from docling.datamodel.accelerator_options import AcceleratorOptions
-from docling.datamodel.base_models import Page, VlmPrediction
+from docling.datamodel.base_models import Page, VlmPrediction, VlmPredictionToken
 from docling.datamodel.document import ConversionResult
 from docling.datamodel.pipeline_options_vlm_model import (
     InlineVlmOptions,
@@ -88,7 +88,7 @@ class VllmVlmModel(BaseVlmPageModel, HuggingFaceModelDownloadMixin):
         vlm_options: InlineVlmOptions,
     ):
         self.enabled = enabled
-        self.vlm_options = vlm_options
+        self.vlm_options: InlineVlmOptions = vlm_options
 
         self.llm = None
         self.sampling_params = None
@@ -234,6 +234,7 @@ class VllmVlmModel(BaseVlmPageModel, HuggingFaceModelDownloadMixin):
                     pages_with_images.append(page)
 
                 if images:
+                    with TimeRecorder(conv_res, "vlm_inference"):
                         predictions = list(self.process_images(images, user_prompts))
                     for page, prediction in zip(pages_with_images, predictions):
                         page.predictions.vlm_response = prediction
@@ -300,13 +301,34 @@ class VllmVlmModel(BaseVlmPageModel, HuggingFaceModelDownloadMixin):
         # Optional debug
         if outputs:
             try:
-                num_tokens = len(outputs[0].outputs[0].token_ids)
+                num_tokens_within_batch = len(outputs[0].outputs[0].token_ids)
-                _log.debug(f"Generated {num_tokens} tokens in {generation_time:.2f}s.")
+                _log.debug(
+                    f"Generated {num_tokens_within_batch} tokens for batch in {generation_time:.2f}s."
+                )
             except Exception:
-                pass
+                num_tokens_within_batch = 0
 
         # Emit predictions
         for output in outputs:
             text = output.outputs[0].text if output.outputs else ""
+            stop_reason = output.outputs[0].stop_reason if output.outputs else ""
+            generated_tokens = [
+                VlmPredictionToken(token=int(p)) for p in output.outputs[0].token_ids
+            ]
+            num_tokens = len(generated_tokens)
             decoded_text = self.vlm_options.decode_response(text)
-            yield VlmPrediction(text=decoded_text, generation_time=generation_time)
+            if self.vlm_options.track_generated_tokens:
+                yield VlmPrediction(
+                    text=decoded_text,
+                    generation_time=generation_time,
+                    num_tokens=num_tokens,
+                    stop_reason=stop_reason,
+                    generated_tokens=generated_tokens,
+                )
+            else:
+                yield VlmPrediction(
+                    text=decoded_text,
+                    generation_time=generation_time,
+                    num_tokens=num_tokens,
+                    stop_reason=stop_reason,
+                )

docling/utils/api_image_request.py

@@ -2,7 +2,7 @@ import base64
 import json
 import logging
 from io import BytesIO
-from typing import Optional
+from typing import Dict, List, Optional, Tuple
 
 import requests
 from PIL import Image
@@ -21,7 +21,7 @@ def api_image_request(
     timeout: float = 20,
     headers: Optional[dict[str, str]] = None,
     **params,
-) -> str:
+) -> Tuple[str, Optional[int]]:
     img_io = BytesIO()
     image.save(img_io, "PNG")
     image_base64 = base64.b64encode(img_io.getvalue()).decode("utf-8")
@@ -60,7 +60,8 @@ def api_image_request(
 
     api_resp = OpenAiApiResponse.model_validate_json(r.text)
     generated_text = api_resp.choices[0].message.content.strip()
-    return generated_text
+    num_tokens = api_resp.usage.total_tokens
+    return generated_text, num_tokens
 
 
 def api_image_request_streaming(
@@ -72,7 +73,7 @@ def api_image_request_streaming(
     headers: Optional[dict[str, str]] = None,
     generation_stoppers: list[GenerationStopper] = [],
     **params,
-) -> str:
+) -> Tuple[str, Optional[int]]:
     """
     Stream a chat completion from an OpenAI-compatible server (e.g., vLLM).
     Parses SSE lines: 'data: {json}\\n\\n', terminated by 'data: [DONE]'.
@@ -150,6 +151,16 @@ def api_image_request_streaming(
                 _log.debug("Unexpected SSE chunk shape: %s", e)
                 piece = ""
 
+            # Try to extract token count
+            num_tokens = None
+            try:
+                if "usage" in obj:
+                    usage = obj["usage"]
+                    num_tokens = usage.get("total_tokens")
+            except Exception as e:
+                num_tokens = None
+                _log.debug("Usage key not included in response: %s", e)
+
             if piece:
                 full_text.append(piece)
                 for stopper in generation_stoppers:
@@ -162,6 +173,6 @@ def api_image_request_streaming(
                         # closing the connection when we exit the 'with' block.
                         # vLLM/OpenAI-compatible servers will detect the client disconnect
                         # and abort the request server-side.
-                        return "".join(full_text)
+                        return "".join(full_text), num_tokens
 
-        return "".join(full_text)
+        return "".join(full_text), num_tokens