Chapter 7 · Section 10

Solutions

Complete reference implementations for the advanced topics exercises, including database adapters, caching, and deployment.

Reference Material

Introduction

This section provides detailed solutions for the exercises in Chapter 7. These implementations demonstrate best practices for building robust, scalable DSPy applications in production environments.

Solution 1: Custom PostgreSQL Adapter

This adapter implements connection pooling and caching using psycopg2.

Python
import dspy
import psycopg2
from psycopg2 import pool
import json

class PostgresAdapter(dspy.Adapter):
    def __init__(self, connection_string):
        self.pool = psycopg2.pool.SimpleConnectionPool(1, 10, connection_string)
        self._init_db()

    def _init_db(self):
        conn = self.pool.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute("""
                    CREATE TABLE IF NOT EXISTS predictions (
                        key TEXT PRIMARY KEY,
                        value JSONB
                    );
                """)
                conn.commit()
        finally:
            self.pool.putconn(conn)

    def get(self, key):
        conn = self.pool.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute("SELECT value FROM predictions WHERE key = %s", (key,))
                result = cur.fetchone()
                return result[0] if result else None
        finally:
            self.pool.putconn(conn)

    def set(self, key, value):
        conn = self.pool.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute("""
                    INSERT INTO predictions (key, value) VALUES (%s, %s)
                    ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value
                """, (key, json.dumps(value)))
                conn.commit()
        finally:
            self.pool.putconn(conn)

Solution 2: Multi-Level Caching System

A sophisticated caching strategy managing Memory (L1), Redis (L2), and Disk (L3).

Python
import redis
import pickle
import os

class MultiLevelCache:
    def __init__(self, redis_url="redis://localhost:6379", disk_path="./cache"):
        self.l1 = {}
        self.l2 = redis.from_url(redis_url)
        self.l3_path = disk_path
        os.makedirs(disk_path, exist_ok=True)

    def get(self, key):
        # Check L1 (Memory)
        if key in self.l1:
            return self.l1[key]
        
        # Check L2 (Redis)
        l2_val = self.l2.get(key)
        if l2_val:
            val = pickle.loads(l2_val)
            self.l1[key] = val  # Promote to L1
            return val
        
        # Check L3 (Disk)
        file_path = os.path.join(self.l3_path, key)
        if os.path.exists(file_path):
            with open(file_path, 'rb') as f:
                val = pickle.load(f)
                self.l2.set(key, pickle.dumps(val)) # Promote to L2
                self.l1[key] = val # Promote to L1
                return val
                
        return None

    def set(self, key, value):
        # Write through to all layers
        self.l1[key] = value
        self.l2.set(key, pickle.dumps(value))
        with open(os.path.join(self.l3_path, key), 'wb') as f:
            pickle.dump(value, f)

Solution 3: Async Streaming RAG

Handling concurrent streams efficiently using asyncio.

Python
import asyncio
import dspy

class AsyncRAGController:
    def __init__(self, rag_module, concurrency=5):
        self.module = rag_module
        self.semaphore = asyncio.Semaphore(concurrency)
        
    async def process_query(self, query):
        async with self.semaphore:
            # Simulate async wrapper for sync DSPy call
            result = await asyncio.to_thread(self.module.forward, question=query)
            return result

    async def ingest_stream(self, document_stream):
        async for doc in document_stream:
            # Fake async ingestion
            await asyncio.sleep(0.01)
            print(f"Ingested: {doc[:20]}...")

    async def run_pipeline(self, queries, doc_stream):
        ingest_task = asyncio.create_task(self.ingest_stream(doc_stream))
        
        results = await asyncio.gather(*(self.process_query(q) for q in queries))
        
        await ingest_task
        return results

Solution 5: Kubernetes Manifest

Complete production deployment configuration.

YAML
apiVersion: apps/v1
kind: Deployment
metadata:
  name: dspy-app
  namespace: adaptive-ai
spec:
  replicas: 3
  selector:
    matchLabels:
      app: dspy-app
  template:
    metadata:
      labels:
        app: dspy-app
    spec:
      containers:
      - name: dspy-server
        image: dspy-app:v1.0
        ports:
        - containerPort: 8000
        resources:
          requests:
            memory: "512Mi"
            cpu: "500m"
          limits:
            memory: "1Gi"
            cpu: "1000m"
        env:
        - name: OPENAI_API_KEY
          valueFrom:
            secretKeyRef:
              name: dspy-secrets
              key: api-key
---
apiVersion: v1
kind: Service
metadata:
  name: dspy-service
spec:
  selector:
    app: dspy-app
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8000
  type: LoadBalancer
---
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: dspy-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: dspy-app
  minReplicas: 3
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 75