fastapi-async-patterns

# FastAPI Async Patterns

Master async patterns in FastAPI for building high-performance,
concurrent APIs with optimal resource usage.

## Basic Async Route Handlers

Understanding async vs sync endpoints in FastAPI.

```python
from fastapi import FastAPI
import time
import asyncio

app = FastAPI()

# Sync endpoint (blocks the event loop)
@app.get('/sync')
def sync_endpoint():
    time.sleep(1)  # Blocks the entire server
    return {'message': 'Completed after 1 second'}

# Async endpoint (non-blocking)
@app.get('/async')
async def async_endpoint():
    await asyncio.sleep(1)  # Other requests can be handled
    return {'message': 'Completed after 1 second'}

# CPU-bound work (use sync)
@app.get('/cpu-intensive')
def cpu_intensive():
    result = sum(i * i for i in range(10000000))
    return {'result': result}

# I/O-bound work (use async)
@app.get('/io-intensive')
async def io_intensive():
    async with httpx.AsyncClient() as client:
        response = await client.get('https://api.example.com/data')
        return response.json()
```

## Async Database Operations

Async database patterns with popular ORMs and libraries.

```python
from fastapi import FastAPI, Depends, HTTPException
from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy import select
import asyncpg
from motor.motor_asyncio import AsyncIOMotorClient
from tortoise import Tortoise
from tortoise.contrib.fastapi import register_tortoise

app = FastAPI()

# SQLAlchemy async setup
DATABASE_URL = 'postgresql+asyncpg://user:pass@localhost/db'
engine = create_async_engine(DATABASE_URL, echo=True, future=True)
AsyncSessionLocal = sessionmaker(
    engine, class_=AsyncSession, expire_on_commit=False
)

async def get_db() -> AsyncSession:
    async with AsyncSessionLocal() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise

@