[Feature] Opt metrics structure (#891)

Signed-off-by: Junhong Liu <98734602+LJH-LBJ@users.noreply.github.com>
Signed-off-by: Junhong Liu <ljh_lbj@163.com>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>

vllm_omni/diffusion/diffusion_engine.py

@@ -102,16 +102,20 @@ class DiffusionEngine:
         if not isinstance(outputs, list):
             outputs = [outputs] if outputs is not None else []
 
+        metrics = {
+            "image_num": int(request.sampling_params.num_outputs_per_prompt),
+            "resolution": int(request.sampling_params.resolution),
+            "postprocess_time_ms": postprocess_time * 1000,
+        }
+        if self.pre_process_func is not None:
+            metrics["preprocessing_time_ms"] = preprocess_time * 1000
+
         # Handle single request or multiple requests
         if len(request.prompts) == 1:
             # Single request: return single OmniRequestOutput
             prompt = request.prompts[0]
             request_id = request.request_ids[0] if request.request_ids else ""
 
-            metrics = {}
-            if output.trajectory_timesteps is not None:
-                metrics["trajectory_timesteps"] = output.trajectory_timesteps
-
             if supports_audio_output(self.od_config.model_class_name):
                 audio_payload = outputs[0] if len(outputs) == 1 else outputs
                 return [
@@ -149,10 +153,6 @@ class DiffusionEngine:
                 request_outputs = outputs[output_idx : output_idx + num_outputs] if output_idx < len(outputs) else []
                 output_idx += num_outputs
 
-                metrics = {}
-                if output.trajectory_timesteps is not None:
-                    metrics["trajectory_timesteps"] = output.trajectory_timesteps
-
                 if supports_audio_output(self.od_config.model_class_name):
                     audio_payload = request_outputs[0] if len(request_outputs) == 1 else request_outputs
                     results.append(