Upload aco/cache_layout.py with huggingface_hub
Browse files- aco/cache_layout.py +68 -172
aco/cache_layout.py
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"""Cache-Aware Prompt Layout
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Optimizes prompt/context structure for prefix-cache reuse.
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Strategy:
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- Keep stable rules in the prefix (system rules, tool descriptions, user preferences)
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- Keep tool descriptions stable
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- Move dynamic content to the suffix (user message, retrieved docs, recent trace, artifacts)
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- Avoid injecting timestamps/random metadata above cache boundary
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- Preserve sticky provider/session routing where useful
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Metrics:
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- cache hit rate
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- warm-cache cost
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- cold-cache cost
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- latency
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- context staleness failures
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"""
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from typing import Dict, List, Tuple, Optional, Any
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from dataclasses import dataclass
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from .config import ACOConfig
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@dataclass
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class PromptLayout:
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prefix_tokens: int
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suffix_tokens: int
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]
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"staleness_failures": 0,
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}
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def layout(
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self,
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content_pieces: Dict[str, str],
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cost_per_1k_input: float = 0.01,
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cache_discount_rate: float = 0.5,
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) -> PromptLayout:
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"""Partition content into prefix (cacheable) and suffix (dynamic)."""
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prefix_pieces = []
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suffix_pieces = []
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for key, text in content_pieces.items():
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if self._is_prefix_content(key):
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prefix_pieces.append(text)
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else:
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prefix = "\n\n".join(
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suffix = "\n\n".join(
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return PromptLayout(
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prefix_tokens=prefix_tokens,
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suffix_tokens=suffix_tokens,
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cache_discount=cache_discount,
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)
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def _is_prefix_content(self, key: str) -> bool:
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"""Determine if a content key belongs in the prefix."""
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# Direct matches
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if key in self.PREFIX_CONTENT_TYPES:
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return True
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if key in self.SUFFIX_CONTENT_TYPES:
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return False
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# Pattern matching
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if any(kw in key.lower() for kw in ["system", "static", "rule", "persona", "schema", "format"]):
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return True
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if any(kw in key.lower() for kw in ["user_", "dynamic", "current", "live", "now", "timestamp"]):
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return False
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# Default: prefix if name suggests stability
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return True
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def optimize_for_provider(
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self,
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layout: PromptLayout,
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provider: str,
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) -> PromptLayout:
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"""Provider-specific cache layout optimizations."""
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provider = provider.lower()
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if "anthropic" in provider:
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# Claude has system prompts that are automatically cached
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# Keep system content separate
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return layout
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elif "openai" in provider:
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# OpenAI has prefix caching on system + first user message
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# Ensure system content is at the very top
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return layout
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elif "gemini" in provider:
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# Gemini has context caching for repeated contexts
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return layout
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elif "deepseek" in provider:
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# DeepSeek has cache hit discounts
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return layout
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return layout
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def measure_hit_rate(self, prefix_tokens: int, cache_hit: bool) -> None:
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"""Update cache statistics."""
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if cache_hit:
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self.cache_stats["warm_runs"] += 1
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else:
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self.cache_stats["cold_runs"] += 1
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total = self.cache_stats["warm_runs"] + self.cache_stats["cold_runs"]
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self.cache_stats["cache_hit_rate"] = self.cache_stats["warm_runs"] / total if total > 0 else 0.0
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# Running average of prefix tokens
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n = total
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self.cache_stats["prefix_tokens_avg"] = (
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(self.cache_stats["prefix_tokens_avg"] * (n - 1) + prefix_tokens) / n
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)
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def
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total = self.cache_stats["warm_runs"] + self.cache_stats["cold_runs"]
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return {
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"
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"
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"
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"
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"
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"staleness_failures": self.cache_stats["staleness_failures"],
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"estimated_cost_saved": self.cache_stats["warm_runs"] * self.cache_stats.get("avg_cache_discount", 0.0),
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}
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"""Cache-Aware Prompt Layout: Optimize prompt structure for prefix-cache reuse."""
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from typing import Dict, List, Tuple
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from dataclasses import dataclass
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@dataclass
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class PromptLayout:
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prefix_content: str
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suffix_content: str
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prefix_tokens: int
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suffix_tokens: int
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cache_boundary: int # token position of cache boundary
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stable_sources: List[str]
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dynamic_sources: List[str]
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CACHE_STABLE_SOURCES = {"system_rules", "tool_descriptions", "user_preferences"}
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CACHE_DYNAMIC_SOURCES = {"recent_messages", "task_plan", "retrieved_docs", "artifacts"}
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class CacheAwareLayout:
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def __init__(self, session_id: str = None):
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self.session_id = session_id
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self._prev_prefix_hash = None
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self.cache_hits = 0
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self.cache_misses = 0
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self.total_prefix_tokens = 0
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self.total_suffix_tokens = 0
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def layout(self, sources: Dict[str, str], context_budget) -> PromptLayout:
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prefix_parts = []
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suffix_parts = []
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stable = []
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dynamic = []
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prefix_tokens = 0
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suffix_tokens = 0
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for source_name, content in sources.items():
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token_est = len(content) // 4 # rough estimate
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if source_name in context_budget.cache_prefix:
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prefix_parts.append(f"# {source_name}\n{content}")
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prefix_tokens += token_est
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stable.append(source_name)
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elif source_name in context_budget.dynamic_suffix:
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suffix_parts.append(f"# {source_name}\n{content}")
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suffix_tokens += token_est
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dynamic.append(source_name)
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elif source_name in context_budget.keep_exact:
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prefix_parts.append(f"# {source_name}\n{content}")
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prefix_tokens += token_est
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stable.append(source_name)
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else:
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suffix_parts.append(f"# {source_name}\n{content}")
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suffix_tokens += token_est
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dynamic.append(source_name)
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prefix = "\n\n".join(prefix_parts)
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suffix = "\n\n".join(suffix_parts)
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# Check cache hit
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import hashlib
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prefix_hash = hashlib.md5(prefix.encode()).hexdigest()
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if self._prev_prefix_hash == prefix_hash:
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self.cache_hits += 1
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else:
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self.cache_misses += 1
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self._prev_prefix_hash = prefix_hash
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self.total_prefix_tokens += prefix_tokens
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self.total_suffix_tokens += suffix_tokens
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return PromptLayout(
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prefix_content=prefix,
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suffix_content=suffix,
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prefix_tokens=prefix_tokens,
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suffix_tokens=suffix_tokens,
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cache_boundary=prefix_tokens,
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stable_sources=stable,
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dynamic_sources=dynamic,
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)
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def stats(self) -> Dict:
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total = self.cache_hits + self.cache_misses
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return {
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"cache_hit_rate": self.cache_hits / max(total, 1),
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"total_cache_hits": self.cache_hits,
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"total_cache_misses": self.cache_misses,
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"avg_prefix_tokens": self.total_prefix_tokens / max(total, 1),
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"avg_suffix_tokens": self.total_suffix_tokens / max(total, 1),
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}
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