feat(context): implement Redis-based caching layer (#84)

Phase 6 of Context Management Engine - Caching Layer:

- Add ContextCache with Redis integration
- Support fingerprint-based assembled context caching
- Support token count caching (model-specific)
- Support score caching (scorer + context + query)
- Add in-memory fallback with LRU eviction
- Add cache invalidation with pattern matching
- Add cache statistics reporting

Key features:
- Hierarchical cache key structure (ctx:type:hash)
- Automatic TTL expiration
- Memory cache for fast repeated access
- Graceful degradation when Redis unavailable

Tests: 29 new tests, 285 total context tests passing

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
2026-01-04 02:41:21 +01:00
parent 7828d35e06
commit c2466ab401
4 changed files with 907 additions and 0 deletions

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@@ -85,6 +85,9 @@ from .adapters import (
OpenAIAdapter,
)
# Cache
from .cache import ContextCache
# Prioritization
from .prioritization import (
ContextRanker,
@@ -132,6 +135,8 @@ __all__ = [
"BudgetAllocator",
"TokenBudget",
"TokenCalculator",
# Cache
"ContextCache",
# Compression
"ContextCompressor",
"TruncationResult",

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@@ -3,3 +3,9 @@ Context Cache Module.
Provides Redis-based caching for assembled contexts.
"""
from .context_cache import ContextCache
__all__ = [
"ContextCache",
]

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@@ -0,0 +1,417 @@
"""
Context Cache Implementation.
Provides Redis-based caching for context operations including
assembled contexts, token counts, and scoring results.
"""
import hashlib
import json
import logging
from typing import TYPE_CHECKING, Any
from ..config import ContextSettings, get_context_settings
from ..exceptions import CacheError
from ..types import AssembledContext, BaseContext
if TYPE_CHECKING:
from redis.asyncio import Redis
logger = logging.getLogger(__name__)
class ContextCache:
"""
Redis-based caching for context operations.
Provides caching for:
- Assembled contexts (fingerprint-based)
- Token counts (content hash-based)
- Scoring results (context + query hash-based)
Cache keys use a hierarchical structure:
- ctx:assembled:{fingerprint}
- ctx:tokens:{model}:{content_hash}
- ctx:score:{scorer}:{context_hash}:{query_hash}
"""
def __init__(
self,
redis: "Redis | None" = None,
settings: ContextSettings | None = None,
) -> None:
"""
Initialize the context cache.
Args:
redis: Redis connection (optional for testing)
settings: Cache settings
"""
self._redis = redis
self._settings = settings or get_context_settings()
self._prefix = self._settings.cache_prefix
self._ttl = self._settings.cache_ttl_seconds
# In-memory fallback cache when Redis unavailable
self._memory_cache: dict[str, tuple[str, float]] = {}
self._max_memory_items = 1000
def set_redis(self, redis: "Redis") -> None:
"""Set Redis connection."""
self._redis = redis
@property
def is_enabled(self) -> bool:
"""Check if caching is enabled and available."""
return self._settings.cache_enabled and self._redis is not None
def _cache_key(self, *parts: str) -> str:
"""
Build a cache key from parts.
Args:
*parts: Key components
Returns:
Colon-separated cache key
"""
return f"{self._prefix}:{':'.join(parts)}"
@staticmethod
def _hash_content(content: str) -> str:
"""
Compute hash of content for cache key.
Args:
content: Content to hash
Returns:
32-character hex hash
"""
return hashlib.sha256(content.encode()).hexdigest()[:32]
def compute_fingerprint(
self,
contexts: list[BaseContext],
query: str,
model: str,
) -> str:
"""
Compute a fingerprint for a context assembly request.
The fingerprint is based on:
- Context content and metadata
- Query string
- Target model
Args:
contexts: List of contexts
query: Query string
model: Model name
Returns:
32-character hex fingerprint
"""
# Build a deterministic representation
context_data = []
for ctx in contexts:
context_data.append({
"type": ctx.get_type().value,
"content": ctx.content,
"source": ctx.source,
"priority": ctx.priority, # Already an int
})
data = {
"contexts": context_data,
"query": query,
"model": model,
}
content = json.dumps(data, sort_keys=True)
return self._hash_content(content)
async def get_assembled(
self,
fingerprint: str,
) -> AssembledContext | None:
"""
Get cached assembled context by fingerprint.
Args:
fingerprint: Assembly fingerprint
Returns:
Cached AssembledContext or None if not found
"""
if not self.is_enabled:
return None
key = self._cache_key("assembled", fingerprint)
try:
data = await self._redis.get(key) # type: ignore
if data:
logger.debug(f"Cache hit for assembled context: {fingerprint}")
result = AssembledContext.from_json(data)
result.cache_hit = True
result.cache_key = fingerprint
return result
except Exception as e:
logger.warning(f"Cache get error: {e}")
raise CacheError(f"Failed to get assembled context: {e}") from e
return None
async def set_assembled(
self,
fingerprint: str,
context: AssembledContext,
ttl: int | None = None,
) -> None:
"""
Cache an assembled context.
Args:
fingerprint: Assembly fingerprint
context: Assembled context to cache
ttl: Optional TTL override in seconds
"""
if not self.is_enabled:
return
key = self._cache_key("assembled", fingerprint)
expire = ttl or self._ttl
try:
await self._redis.setex(key, expire, context.to_json()) # type: ignore
logger.debug(f"Cached assembled context: {fingerprint}")
except Exception as e:
logger.warning(f"Cache set error: {e}")
raise CacheError(f"Failed to cache assembled context: {e}") from e
async def get_token_count(
self,
content: str,
model: str | None = None,
) -> int | None:
"""
Get cached token count.
Args:
content: Content to look up
model: Model name for model-specific tokenization
Returns:
Cached token count or None if not found
"""
model_key = model or "default"
content_hash = self._hash_content(content)
key = self._cache_key("tokens", model_key, content_hash)
# Try in-memory first
if key in self._memory_cache:
return int(self._memory_cache[key][0])
if not self.is_enabled:
return None
try:
data = await self._redis.get(key) # type: ignore
if data:
count = int(data)
# Store in memory for faster subsequent access
self._set_memory(key, str(count))
return count
except Exception as e:
logger.warning(f"Cache get error for tokens: {e}")
return None
async def set_token_count(
self,
content: str,
count: int,
model: str | None = None,
ttl: int | None = None,
) -> None:
"""
Cache a token count.
Args:
content: Content that was counted
count: Token count
model: Model name
ttl: Optional TTL override in seconds
"""
model_key = model or "default"
content_hash = self._hash_content(content)
key = self._cache_key("tokens", model_key, content_hash)
expire = ttl or self._ttl
# Always store in memory
self._set_memory(key, str(count))
if not self.is_enabled:
return
try:
await self._redis.setex(key, expire, str(count)) # type: ignore
except Exception as e:
logger.warning(f"Cache set error for tokens: {e}")
async def get_score(
self,
scorer_name: str,
context_id: str,
query: str,
) -> float | None:
"""
Get cached score.
Args:
scorer_name: Name of the scorer
context_id: Context identifier
query: Query string
Returns:
Cached score or None if not found
"""
query_hash = self._hash_content(query)[:16]
key = self._cache_key("score", scorer_name, context_id, query_hash)
# Try in-memory first
if key in self._memory_cache:
return float(self._memory_cache[key][0])
if not self.is_enabled:
return None
try:
data = await self._redis.get(key) # type: ignore
if data:
score = float(data)
self._set_memory(key, str(score))
return score
except Exception as e:
logger.warning(f"Cache get error for score: {e}")
return None
async def set_score(
self,
scorer_name: str,
context_id: str,
query: str,
score: float,
ttl: int | None = None,
) -> None:
"""
Cache a score.
Args:
scorer_name: Name of the scorer
context_id: Context identifier
query: Query string
score: Score value
ttl: Optional TTL override in seconds
"""
query_hash = self._hash_content(query)[:16]
key = self._cache_key("score", scorer_name, context_id, query_hash)
expire = ttl or self._ttl
# Always store in memory
self._set_memory(key, str(score))
if not self.is_enabled:
return
try:
await self._redis.setex(key, expire, str(score)) # type: ignore
except Exception as e:
logger.warning(f"Cache set error for score: {e}")
async def invalidate(self, pattern: str) -> int:
"""
Invalidate cache entries matching a pattern.
Args:
pattern: Key pattern (supports * wildcard)
Returns:
Number of keys deleted
"""
if not self.is_enabled:
return 0
full_pattern = self._cache_key(pattern)
deleted = 0
try:
async for key in self._redis.scan_iter(match=full_pattern): # type: ignore
await self._redis.delete(key) # type: ignore
deleted += 1
logger.info(f"Invalidated {deleted} cache entries matching {pattern}")
except Exception as e:
logger.warning(f"Cache invalidation error: {e}")
raise CacheError(f"Failed to invalidate cache: {e}") from e
return deleted
async def clear_all(self) -> int:
"""
Clear all context cache entries.
Returns:
Number of keys deleted
"""
self._memory_cache.clear()
return await self.invalidate("*")
def _set_memory(self, key: str, value: str) -> None:
"""
Set a value in the memory cache.
Uses LRU-style eviction when max items reached.
Args:
key: Cache key
value: Value to store
"""
import time
if len(self._memory_cache) >= self._max_memory_items:
# Evict oldest entries
sorted_keys = sorted(
self._memory_cache.keys(),
key=lambda k: self._memory_cache[k][1],
)
for k in sorted_keys[: len(sorted_keys) // 2]:
del self._memory_cache[k]
self._memory_cache[key] = (value, time.time())
async def get_stats(self) -> dict[str, Any]:
"""
Get cache statistics.
Returns:
Dictionary with cache stats
"""
stats = {
"enabled": self._settings.cache_enabled,
"redis_available": self._redis is not None,
"memory_items": len(self._memory_cache),
"ttl_seconds": self._ttl,
}
if self.is_enabled:
try:
# Get Redis info
info = await self._redis.info("memory") # type: ignore
stats["redis_memory_used"] = info.get("used_memory_human", "unknown")
except Exception:
pass
return stats

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@@ -0,0 +1,479 @@
"""Tests for context cache module."""
from unittest.mock import AsyncMock, MagicMock
import pytest
from app.services.context.cache import ContextCache
from app.services.context.config import ContextSettings
from app.services.context.exceptions import CacheError
from app.services.context.types import (
AssembledContext,
ContextPriority,
KnowledgeContext,
SystemContext,
TaskContext,
)
class TestContextCacheBasics:
"""Basic tests for ContextCache."""
def test_creation(self) -> None:
"""Test cache creation without Redis."""
cache = ContextCache()
assert cache._redis is None
assert not cache.is_enabled
def test_creation_with_settings(self) -> None:
"""Test cache creation with custom settings."""
settings = ContextSettings(
cache_prefix="test",
cache_ttl_seconds=60,
)
cache = ContextCache(settings=settings)
assert cache._prefix == "test"
assert cache._ttl == 60
def test_set_redis(self) -> None:
"""Test setting Redis connection."""
cache = ContextCache()
mock_redis = MagicMock()
cache.set_redis(mock_redis)
assert cache._redis is mock_redis
def test_is_enabled(self) -> None:
"""Test is_enabled property."""
settings = ContextSettings(cache_enabled=True)
cache = ContextCache(settings=settings)
assert not cache.is_enabled # No Redis
cache.set_redis(MagicMock())
assert cache.is_enabled
# Disabled in settings
settings2 = ContextSettings(cache_enabled=False)
cache2 = ContextCache(redis=MagicMock(), settings=settings2)
assert not cache2.is_enabled
def test_cache_key(self) -> None:
"""Test cache key generation."""
cache = ContextCache()
key = cache._cache_key("assembled", "abc123")
assert key == "ctx:assembled:abc123"
def test_hash_content(self) -> None:
"""Test content hashing."""
hash1 = ContextCache._hash_content("hello world")
hash2 = ContextCache._hash_content("hello world")
hash3 = ContextCache._hash_content("different")
assert hash1 == hash2
assert hash1 != hash3
assert len(hash1) == 32
class TestFingerprintComputation:
"""Tests for fingerprint computation."""
def test_compute_fingerprint(self) -> None:
"""Test fingerprint computation."""
cache = ContextCache()
contexts = [
SystemContext(content="System", source="system"),
TaskContext(content="Task", source="task"),
]
fp1 = cache.compute_fingerprint(contexts, "query", "claude-3")
fp2 = cache.compute_fingerprint(contexts, "query", "claude-3")
fp3 = cache.compute_fingerprint(contexts, "different", "claude-3")
assert fp1 == fp2 # Same inputs = same fingerprint
assert fp1 != fp3 # Different query = different fingerprint
assert len(fp1) == 32
def test_fingerprint_includes_priority(self) -> None:
"""Test that fingerprint changes with priority."""
cache = ContextCache()
# Use KnowledgeContext since SystemContext has __post_init__ that may override
ctx1 = [
KnowledgeContext(
content="Knowledge",
source="docs",
priority=ContextPriority.NORMAL.value,
)
]
ctx2 = [
KnowledgeContext(
content="Knowledge",
source="docs",
priority=ContextPriority.HIGH.value,
)
]
fp1 = cache.compute_fingerprint(ctx1, "query", "claude-3")
fp2 = cache.compute_fingerprint(ctx2, "query", "claude-3")
assert fp1 != fp2
def test_fingerprint_includes_model(self) -> None:
"""Test that fingerprint changes with model."""
cache = ContextCache()
contexts = [SystemContext(content="System", source="system")]
fp1 = cache.compute_fingerprint(contexts, "query", "claude-3")
fp2 = cache.compute_fingerprint(contexts, "query", "gpt-4")
assert fp1 != fp2
class TestMemoryCache:
"""Tests for in-memory caching."""
def test_memory_cache_fallback(self) -> None:
"""Test memory cache when Redis unavailable."""
cache = ContextCache()
# Should use memory cache
cache._set_memory("test-key", "42")
assert "test-key" in cache._memory_cache
assert cache._memory_cache["test-key"][0] == "42"
def test_memory_cache_eviction(self) -> None:
"""Test memory cache eviction."""
cache = ContextCache()
cache._max_memory_items = 10
# Fill cache
for i in range(15):
cache._set_memory(f"key-{i}", f"value-{i}")
# Should have evicted some items
assert len(cache._memory_cache) < 15
class TestAssembledContextCache:
"""Tests for assembled context caching."""
@pytest.mark.asyncio
async def test_get_assembled_no_redis(self) -> None:
"""Test get_assembled without Redis returns None."""
cache = ContextCache()
result = await cache.get_assembled("fingerprint")
assert result is None
@pytest.mark.asyncio
async def test_get_assembled_not_found(self) -> None:
"""Test get_assembled when key not found."""
mock_redis = AsyncMock()
mock_redis.get.return_value = None
settings = ContextSettings(cache_enabled=True)
cache = ContextCache(redis=mock_redis, settings=settings)
result = await cache.get_assembled("fingerprint")
assert result is None
@pytest.mark.asyncio
async def test_get_assembled_found(self) -> None:
"""Test get_assembled when key found."""
# Create a context
ctx = AssembledContext(
content="Test content",
total_tokens=100,
context_count=2,
)
mock_redis = AsyncMock()
mock_redis.get.return_value = ctx.to_json()
settings = ContextSettings(cache_enabled=True)
cache = ContextCache(redis=mock_redis, settings=settings)
result = await cache.get_assembled("fingerprint")
assert result is not None
assert result.content == "Test content"
assert result.total_tokens == 100
assert result.cache_hit is True
assert result.cache_key == "fingerprint"
@pytest.mark.asyncio
async def test_set_assembled(self) -> None:
"""Test set_assembled."""
mock_redis = AsyncMock()
settings = ContextSettings(cache_enabled=True, cache_ttl_seconds=60)
cache = ContextCache(redis=mock_redis, settings=settings)
ctx = AssembledContext(
content="Test content",
total_tokens=100,
context_count=2,
)
await cache.set_assembled("fingerprint", ctx)
mock_redis.setex.assert_called_once()
call_args = mock_redis.setex.call_args
assert call_args[0][0] == "ctx:assembled:fingerprint"
assert call_args[0][1] == 60 # TTL
@pytest.mark.asyncio
async def test_set_assembled_custom_ttl(self) -> None:
"""Test set_assembled with custom TTL."""
mock_redis = AsyncMock()
settings = ContextSettings(cache_enabled=True)
cache = ContextCache(redis=mock_redis, settings=settings)
ctx = AssembledContext(
content="Test",
total_tokens=10,
context_count=1,
)
await cache.set_assembled("fp", ctx, ttl=120)
call_args = mock_redis.setex.call_args
assert call_args[0][1] == 120
@pytest.mark.asyncio
async def test_cache_error_on_get(self) -> None:
"""Test CacheError raised on Redis error."""
mock_redis = AsyncMock()
mock_redis.get.side_effect = Exception("Redis error")
settings = ContextSettings(cache_enabled=True)
cache = ContextCache(redis=mock_redis, settings=settings)
with pytest.raises(CacheError):
await cache.get_assembled("fingerprint")
@pytest.mark.asyncio
async def test_cache_error_on_set(self) -> None:
"""Test CacheError raised on Redis error."""
mock_redis = AsyncMock()
mock_redis.setex.side_effect = Exception("Redis error")
settings = ContextSettings(cache_enabled=True)
cache = ContextCache(redis=mock_redis, settings=settings)
ctx = AssembledContext(
content="Test",
total_tokens=10,
context_count=1,
)
with pytest.raises(CacheError):
await cache.set_assembled("fp", ctx)
class TestTokenCountCache:
"""Tests for token count caching."""
@pytest.mark.asyncio
async def test_get_token_count_memory_fallback(self) -> None:
"""Test get_token_count uses memory cache."""
cache = ContextCache()
# Set in memory
key = cache._cache_key("tokens", "default", cache._hash_content("hello"))
cache._set_memory(key, "42")
result = await cache.get_token_count("hello")
assert result == 42
@pytest.mark.asyncio
async def test_set_token_count_memory(self) -> None:
"""Test set_token_count stores in memory."""
cache = ContextCache()
await cache.set_token_count("hello", 42)
result = await cache.get_token_count("hello")
assert result == 42
@pytest.mark.asyncio
async def test_set_token_count_with_model(self) -> None:
"""Test set_token_count with model-specific tokenization."""
mock_redis = AsyncMock()
settings = ContextSettings(cache_enabled=True)
cache = ContextCache(redis=mock_redis, settings=settings)
await cache.set_token_count("hello", 42, model="claude-3")
await cache.set_token_count("hello", 50, model="gpt-4")
# Different models should have different keys
assert mock_redis.setex.call_count == 2
calls = mock_redis.setex.call_args_list
key1 = calls[0][0][0]
key2 = calls[1][0][0]
assert "claude-3" in key1
assert "gpt-4" in key2
class TestScoreCache:
"""Tests for score caching."""
@pytest.mark.asyncio
async def test_get_score_memory_fallback(self) -> None:
"""Test get_score uses memory cache."""
cache = ContextCache()
# Set in memory
query_hash = cache._hash_content("query")[:16]
key = cache._cache_key("score", "relevance", "ctx-123", query_hash)
cache._set_memory(key, "0.85")
result = await cache.get_score("relevance", "ctx-123", "query")
assert result == 0.85
@pytest.mark.asyncio
async def test_set_score_memory(self) -> None:
"""Test set_score stores in memory."""
cache = ContextCache()
await cache.set_score("relevance", "ctx-123", "query", 0.85)
result = await cache.get_score("relevance", "ctx-123", "query")
assert result == 0.85
@pytest.mark.asyncio
async def test_set_score_with_redis(self) -> None:
"""Test set_score with Redis."""
mock_redis = AsyncMock()
settings = ContextSettings(cache_enabled=True)
cache = ContextCache(redis=mock_redis, settings=settings)
await cache.set_score("relevance", "ctx-123", "query", 0.85)
mock_redis.setex.assert_called_once()
class TestCacheInvalidation:
"""Tests for cache invalidation."""
@pytest.mark.asyncio
async def test_invalidate_pattern(self) -> None:
"""Test invalidate with pattern."""
mock_redis = AsyncMock()
# Set up scan_iter to return matching keys
async def mock_scan_iter(match=None):
for key in ["ctx:assembled:1", "ctx:assembled:2"]:
yield key
mock_redis.scan_iter = mock_scan_iter
settings = ContextSettings(cache_enabled=True)
cache = ContextCache(redis=mock_redis, settings=settings)
deleted = await cache.invalidate("assembled:*")
assert deleted == 2
assert mock_redis.delete.call_count == 2
@pytest.mark.asyncio
async def test_clear_all(self) -> None:
"""Test clear_all."""
mock_redis = AsyncMock()
async def mock_scan_iter(match=None):
for key in ["ctx:1", "ctx:2", "ctx:3"]:
yield key
mock_redis.scan_iter = mock_scan_iter
settings = ContextSettings(cache_enabled=True)
cache = ContextCache(redis=mock_redis, settings=settings)
# Add to memory cache
cache._set_memory("test", "value")
assert len(cache._memory_cache) > 0
deleted = await cache.clear_all()
assert deleted == 3
assert len(cache._memory_cache) == 0
class TestCacheStats:
"""Tests for cache statistics."""
@pytest.mark.asyncio
async def test_get_stats_no_redis(self) -> None:
"""Test get_stats without Redis."""
cache = ContextCache()
cache._set_memory("key", "value")
stats = await cache.get_stats()
assert stats["enabled"] is True
assert stats["redis_available"] is False
assert stats["memory_items"] == 1
@pytest.mark.asyncio
async def test_get_stats_with_redis(self) -> None:
"""Test get_stats with Redis."""
mock_redis = AsyncMock()
mock_redis.info.return_value = {"used_memory_human": "1.5M"}
settings = ContextSettings(cache_enabled=True, cache_ttl_seconds=300)
cache = ContextCache(redis=mock_redis, settings=settings)
stats = await cache.get_stats()
assert stats["enabled"] is True
assert stats["redis_available"] is True
assert stats["ttl_seconds"] == 300
assert stats["redis_memory_used"] == "1.5M"
class TestCacheIntegration:
"""Integration tests for cache."""
@pytest.mark.asyncio
async def test_full_workflow(self) -> None:
"""Test complete cache workflow."""
mock_redis = AsyncMock()
mock_redis.get.return_value = None
settings = ContextSettings(cache_enabled=True)
cache = ContextCache(redis=mock_redis, settings=settings)
contexts = [
SystemContext(content="System", source="system"),
KnowledgeContext(content="Knowledge", source="docs"),
]
# Compute fingerprint
fp = cache.compute_fingerprint(contexts, "query", "claude-3")
assert len(fp) == 32
# Check cache (miss)
result = await cache.get_assembled(fp)
assert result is None
# Create and cache assembled context
assembled = AssembledContext(
content="Assembled content",
total_tokens=100,
context_count=2,
model="claude-3",
)
await cache.set_assembled(fp, assembled)
# Verify setex was called
mock_redis.setex.assert_called_once()
# Mock cache hit
mock_redis.get.return_value = assembled.to_json()
result = await cache.get_assembled(fp)
assert result is not None
assert result.cache_hit is True
assert result.content == "Assembled content"