Implement selective caching for RPC method responses

.gitignore

@@ -1,3 +1,4 @@
 .env
 __pycache__
 *.db
+cache

cache.py

@@ -1,5 +1,6 @@
 import json
 import os
+import time
 from typing import Dict, Any, Optional
 import diskcache
 
@@ -19,11 +20,34 @@ class Cache:
     
     def get(self, method: str, params: Dict[str, Any]) -> Optional[Dict[str, Any]]:
         key = self._make_key(method, params)
-        return self.cache.get(key)
+        cached_data = self.cache.get(key)
+        
+        if cached_data is None:
+            return None
+        
+        # Check if cached data has TTL and if it's expired
+        if isinstance(cached_data, dict) and '_cache_expiry' in cached_data:
+            if time.time() > cached_data['_cache_expiry']:
+                # Remove expired entry
+                self.cache.delete(key)
+                return None
+            # Remove cache metadata before returning
+            response = cached_data.copy()
+            del response['_cache_expiry']
+            return response
+        
+        return cached_data
     
-    def set(self, method: str, params: Dict[str, Any], response: Dict[str, Any]) -> None:
+    def set(self, method: str, params: Dict[str, Any], response: Dict[str, Any], ttl: Optional[int] = None) -> None:
         key = self._make_key(method, params)
-        self.cache.set(key, response)
+        
+        # Add TTL metadata if specified
+        if ttl is not None:
+            cached_response = response.copy()
+            cached_response['_cache_expiry'] = time.time() + ttl
+            self.cache.set(key, cached_response)
+        else:
+            self.cache.set(key, response)
     
     def size_check(self) -> Dict[str, Any]:
         stats = self.cache.stats()

cache_policy.py

@@ -0,0 +1,95 @@
+from typing import Dict, Any, Optional
+import time
+
+
+class CachePolicy:
+    """
+    Determines caching behavior for Solana RPC methods based on their characteristics.
+    """
+
+    # Methods that return immutable data - cache indefinitely
+    CACHEABLE_IMMUTABLE = {
+        'getGenesisHash'         # Network genesis hash never changes
+    }
+
+    # Methods with time-based TTL caching based on data change frequency
+    CACHEABLE_WITH_TTL = {
+        # Network/validator information - changes periodically
+        'getVoteAccounts': 120,         # Validator vote accounts change every few minutes
+        'getSupply': 300,               # Total SOL supply changes slowly
+
+        # Epoch and network info - changes with epoch boundaries (~2-3 days)
+        'getEpochInfo': 3600,           # Current epoch info changes slowly
+        'getInflationRate': 1800,       # Inflation rate changes infrequently
+        'getInflationGovernor': 3600,   # Inflation governor params rarely change
+
+        # Network constants - change very rarely or never
+        'getEpochSchedule': 86400,      # Epoch schedule rarely changes
+        'getVersion': 3600,             # RPC version changes occasionally
+        'getIdentity': 3600,            # Node identity changes rarely
+
+        # Never change for the given parameters but will add new entry in the DB if the input parameters change
+        'getBlock': 86400,
+        'getTransaction':86400
+    }
+
+    def should_cache(self, method: str, params: Dict[str, Any]) -> bool:
+        """
+        Determine if a method should be cached based on the method name and parameters.
+
+        Args:
+            method: The RPC method name
+            params: The method parameters
+
+        Returns:
+            True if the method should be cached, False otherwise
+        """
+        if method in self.CACHEABLE_IMMUTABLE:
+            # For getBlock, only cache finalized blocks
+            if method == 'getBlock':
+                commitment = self._get_commitment(params)
+                return commitment == 'finalized'
+            return True
+
+        if method in self.CACHEABLE_WITH_TTL:
+            return True
+
+        # Default to not caching unknown methods
+        return False
+
+    def get_cache_ttl(self, method: str, params: Dict[str, Any]) -> Optional[int]:
+        """
+        Get the Time To Live (TTL) for a cached method in seconds.
+
+        Args:
+            method: The RPC method name
+            params: The method parameters
+
+        Returns:
+            TTL in seconds, or None for indefinite caching
+        """
+        if method in self.CACHEABLE_IMMUTABLE:
+            return None  # Cache indefinitely
+
+        if method in self.CACHEABLE_WITH_TTL:
+            return self.CACHEABLE_WITH_TTL[method]
+
+        return None
+
+    def _get_commitment(self, params: Dict[str, Any]) -> str:
+        """
+        Extract the commitment level from RPC parameters.
+
+        Args:
+            params: The method parameters
+
+        Returns:
+            The commitment level, defaults to 'processed'
+        """
+        if isinstance(params, list) and len(params) > 1:
+            if isinstance(params[1], dict) and 'commitment' in params[1]:
+                return params[1]['commitment']
+        elif isinstance(params, dict) and 'commitment' in params:
+            return params['commitment']
+
+        return 'processed'  # Default commitment level

main.py

@@ -36,7 +36,6 @@ def load_config() -> dict:
     return {
         "proxy_port": int(os.getenv("PROXY_PORT", 8545)),
         "cache_size_gb": int(os.getenv("CACHE_SIZE_GB", 100)),
-        "disable_cache": os.getenv("DISABLE_CACHE", "true").lower() == "true",
         "backoff_minutes": int(os.getenv("BACKOFF_MINUTES", 30)),
         "log_level": os.getenv("LOG_LEVEL", "INFO"),
         "error_db_path": os.getenv("ERROR_DB_PATH", "./errors.db"),
@@ -56,7 +55,7 @@ def create_app(config: dict) -> web.Application:
     providers = create_providers()
     cache = Cache(size_limit_gb=config["cache_size_gb"])
     error_logger = ErrorLogger(db_path=config["error_db_path"])
-    router = Router(providers, cache, error_logger, config["disable_cache"])
+    router = Router(providers, cache, error_logger)
 
     app['router'] = router
     app['config'] = config
@@ -73,10 +72,7 @@ def main() -> None:
 
     logger = logging.getLogger(__name__)
     logger.info(f"Starting Solana RPC Proxy on port {config['proxy_port']}")
-    if config['disable_cache']:
-        logger.info("Cache is DISABLED - all responses will be fresh")
-    else:
-        logger.info(f"Cache size limit: {config['cache_size_gb']}GB")
+    logger.info(f"Intelligent caching enabled - Cache size limit: {config['cache_size_gb']}GB")
     logger.info(f"Provider backoff time: {config['backoff_minutes']} minutes")
 
     app = create_app(config)

router.py

@@ -4,22 +4,26 @@ import logging
 from typing import Dict, Any, Optional, List
 from providers import Provider
 from cache import Cache
+from cache_policy import CachePolicy
 from errors import ErrorLogger
 
 
 class Router:
-    def __init__(self, providers: List[Provider], cache: Cache, error_logger: ErrorLogger, disable_cache: bool = False):
+    def __init__(self, providers: List[Provider], cache: Cache, error_logger: ErrorLogger):
         self.providers = providers
         self.cache = cache
+        self.cache_policy = CachePolicy()
         self.error_logger = error_logger
-        self.disable_cache = disable_cache
         self.current_provider_index = 0
         self.logger = logging.getLogger(__name__)
 
     async def route_request(self, method: str, params: Dict[str, Any]) -> Dict[str, Any]:
         request = {"method": method, "params": params}
 
-        if not self.disable_cache:
+        # Check if this method should be cached based on intelligent caching policy
+        should_cache = self.cache_policy.should_cache(method, params)
+
+        if should_cache:
             cached_response = self.cache.get(method, params)
             if cached_response:
                 self.logger.debug(f"Cache hit for {method}")
@@ -42,10 +46,15 @@ class Router:
                 transformed_response["_cached"] = False
                 transformed_response["_provider"] = provider.name
 
-                if not self.disable_cache:
-                    self.cache.set(method, params, transformed_response)
+                # Cache the response if caching policy allows it
+                if should_cache:
+                    ttl = self.cache_policy.get_cache_ttl(method, params)
+                    self.cache.set(method, params, transformed_response, ttl)
+                    cache_info = f" (cached {'indefinitely' if ttl is None else f'for {ttl}s'})"
+                    self.logger.info(f"Request succeeded via {provider.name}{cache_info}")
+                else:
+                    self.logger.info(f"Request succeeded via {provider.name} (not cached)")
 
-                self.logger.info(f"Request succeeded via {provider.name}")
                 return transformed_response
 
             except Exception as error:
@@ -61,11 +70,10 @@ class Router:
     def get_next_available_provider(self) -> Optional[Provider]:
         for _ in range(len(self.providers)):
             provider = self.providers[self.current_provider_index]
+            self.current_provider_index = (self.current_provider_index + 1) % len(self.providers)
 
             if provider.is_available():
                 return provider
-            else:
-                self.current_provider_index = (self.current_provider_index + 1) % len(self.providers)
 
         return None
 

ws_proxy.py

@@ -110,11 +110,6 @@ class WebSocketProxy:
                     transformed_response["_cached"] = False
                     transformed_response["_provider"] = provider.name
 
-                    method = transformed_response.get("method", "")
-                    params = transformed_response.get("params", {})
-                    if method and params and not self.router.disable_cache:
-                        self.router.cache.set(method, params, transformed_response)
-
                     await client_ws.send_str(json.dumps(transformed_response))
                     self.logger.debug(f"Forwarded response to client from {provider.name}: {transformed_response}")