chore: migrate package name to letta (#1775)

Co-authored-by: Charles Packer <packercharles@gmail.com>
Co-authored-by: Shubham Naik <shubham.naik10@gmail.com>
Co-authored-by: Shubham Naik <shub@memgpt.ai>

letta/server/rest_api/utils.py

@@ -0,0 +1,69 @@
+import json
+import traceback
+from enum import Enum
+from typing import AsyncGenerator, Union
+
+from pydantic import BaseModel
+
+from letta.server.rest_api.interface import StreamingServerInterface
+from letta.server.server import SyncServer
+
+# from letta.orm.user import User
+# from letta.orm.utilities import get_db_session
+
+SSE_PREFIX = "data: "
+SSE_SUFFIX = "\n\n"
+SSE_FINISH_MSG = "[DONE]"  # mimic openai
+SSE_ARTIFICIAL_DELAY = 0.1
+
+
+def sse_formatter(data: Union[dict, str]) -> str:
+    """Prefix with 'data: ', and always include double newlines"""
+    assert type(data) in [dict, str], f"Expected type dict or str, got type {type(data)}"
+    data_str = json.dumps(data, separators=(",", ":")) if isinstance(data, dict) else data
+    return f"data: {data_str}\n\n"
+
+
+async def sse_async_generator(generator: AsyncGenerator, finish_message=True):
+    """
+    Wraps a generator for use in Server-Sent Events (SSE), handling errors and ensuring a completion message.
+
+    Args:
+    - generator: An asynchronous generator yielding data chunks.
+
+    Yields:
+    - Formatted Server-Sent Event strings.
+    """
+    try:
+        async for chunk in generator:
+            # yield f"data: {json.dumps(chunk)}\n\n"
+            if isinstance(chunk, BaseModel):
+                chunk = chunk.model_dump()
+            elif isinstance(chunk, Enum):
+                chunk = str(chunk.value)
+            elif not isinstance(chunk, dict):
+                chunk = str(chunk)
+            yield sse_formatter(chunk)
+
+    except Exception as e:
+        print("stream decoder hit error:", e)
+        print(traceback.print_stack())
+        yield sse_formatter({"error": "stream decoder encountered an error"})
+
+    finally:
+        if finish_message:
+            # Signal that the stream is complete
+            yield sse_formatter(SSE_FINISH_MSG)
+
+
+# TODO: why does this double up the interface?
+def get_letta_server() -> SyncServer:
+    # Check if a global server is already instantiated
+    from letta.server.rest_api.app import server
+
+    # assert isinstance(server, SyncServer)
+    return server
+
+
+def get_current_interface() -> StreamingServerInterface:
+    return StreamingServerInterface