# UsageCallbackHandler

> **Class** in `langchain_nvidia_ai_endpoints`

📖 [View in docs](https://reference.langchain.com/python/langchain-nvidia-ai-endpoints/callbacks/UsageCallbackHandler)

Callback Handler that tracks OpenAI info.

## Signature

```python
UsageCallbackHandler(
    self,
)
```

## Extends

- `BaseCallbackHandler`

## Constructors

```python
__init__(
    self,
) -> None
```


## Properties

- `llm_output`
- `price_map`
- `total_tokens`
- `prompt_tokens`
- `completion_tokens`
- `successful_requests`
- `total_cost`
- `model_usage`
- `always_verbose`

## Methods

- [`reset()`](https://reference.langchain.com/python/langchain-nvidia-ai-endpoints/callbacks/UsageCallbackHandler/reset)
- [`on_llm_start()`](https://reference.langchain.com/python/langchain-nvidia-ai-endpoints/callbacks/UsageCallbackHandler/on_llm_start)
- [`on_llm_new_token()`](https://reference.langchain.com/python/langchain-nvidia-ai-endpoints/callbacks/UsageCallbackHandler/on_llm_new_token)
- [`on_llm_end()`](https://reference.langchain.com/python/langchain-nvidia-ai-endpoints/callbacks/UsageCallbackHandler/on_llm_end)

---

[View source on GitHub](https://github.com/langchain-ai/langchain-nvidia/blob/0ca4191cf2239c4990e4706ac1005463f27ff325/libs/ai-endpoints/langchain_nvidia_ai_endpoints/callbacks.py#L144)