core[minor]: Add v2 implementation of astream events (#21638)

Browse Source

This PR introduces a v2 implementation of astream events that removes
intermediate abstractions and fixes some issues with v1 implementation.

The v2 implementation significantly reduces relevant code that's
associated with the astream events implementation together with
overhead.

After this PR, the astream events implementation:

- Uses an async callback handler
- No longer relies on BaseTracer
- No longer relies on json patch

As a result of this re-write, a number of issues were discovered with
the existing implementation.

## Changes in V2 vs. V1

### on_chat_model_end `output`

The outputs associated with `on_chat_model_end` changed depending on
whether it was within a chain or not.

As a root level runnable the output was: 

```python
"data": {"output": AIMessageChunk(content="hello world!", id='some id')}
```

As part of a chain the output was:

```
            "data": {
                "output": {
                    "generations": [
                        [
                            {
                                "generation_info": None,
                                "message": AIMessageChunk(
                                    content="hello world!", id=AnyStr()
                                ),
                                "text": "hello world!",
                                "type": "ChatGenerationChunk",
                            }
                        ]
                    ],
                    "llm_output": None,
                }
            },
```

After this PR, we will always use the simpler representation:

```python
"data": {"output": AIMessageChunk(content="hello world!", id='some id')}
```

**NOTE** Non chat models (i.e., regular LLMs) are still associated with
the more verbose format.

### Remove some `_stream` events

`on_retriever_stream` and `on_tool_stream` events were removed -- these
were not real events, but created as an artifact of implementing on top
of astream_log.

The same information is already available in the `x_on_end` events.

### Propagating Names

Names of runnables have been updated to be more consistent

```python
  model = GenericFakeChatModel(messages=infinite_cycle).configurable_fields(
        messages=ConfigurableField(
            id="messages",
            name="Messages",
            description="Messages return by the LLM",
        )
    )
```

Before:
```python
"name": "RunnableConfigurableFields",
```

After:
```python
"name": "GenericFakeChatModel",
```

### on_retriever_end

on_retriever_end will always return `output` which is a list of
documents (rather than a dict containing a key called "documents")

### Retry events

Removed the `on_retry` callback handler. It was incorrectly showing that
the failed function being retried has invoked `on_chain_end`


https://github.com/langchain-ai/langchain/pull/21638/files#diff-e512e3f84daf23029ebcceb11460f1c82056314653673e450a5831147d8cb84dL1394

...

This commit is contained in:

Eugene Yurtsev

2024-05-15 11:48:47 -04:00

committed by GitHub

parent 54e003268e

commit 5c2cfabec6

8 changed files with 2574 additions and 195 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download Patch File Download Diff File Expand all files Collapse all files

0

libs/core/tests/unit_tests/runnables/test_runnable_events.py → libs/core/tests/unit_tests/runnables/test_runnable_events_v1.py

1694

libs/core/tests/unit_tests/runnables/test_runnable_events_v2.py Normal file

File diff suppressed because it is too large Load Diff