Fix critical issues in TLS session caching implementation

- Add missing Cluster attributes: tls_session_cache_enabled,
  tls_session_cache_size, tls_session_cache_ttl that are referenced
  in tests and documentation
- Remove duplicate TLSSessionCacheOptions class (was defined as both
  ABC and concrete class, causing shadowing)
- Remove unused TLSSessionCacheBase and TLSSessionCacheOptionsBase
  abstract classes from cluster.py
- Remove mid-file ABC import from cluster.py
- Remove unused OrderedDict and namedtuple imports from connection.py
- Remove extra blank line before EndPoint class

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: dkropachev

cassandra/cluster.py

@@ -200,74 +200,6 @@ def _connection_reduce_fn(val,import_fn):
 _DEFAULT_TLS_SESSION_CACHE_TTL = 3600  # 1 hour in seconds
 
 
-# Abstract base classes for TLS session caching - implementations in cassandra.tls
-from abc import ABC, abstractmethod
-
-
-class TLSSessionCacheBase(ABC):
-    """
-    Abstract base class for TLS session caching.
-    
-    Implementations should provide thread-safe caching of TLS sessions
-    to enable session resumption for faster reconnections.
-    """
-    
-    @abstractmethod
-    def get_session(self, endpoint):
-        """
-        Get a cached TLS session for the given endpoint.
-        
-        Args:
-            endpoint: The EndPoint object representing the connection target
-            
-        Returns:
-            ssl.SSLSession object if a valid cached session exists, None otherwise
-        """
-        pass
-    
-    @abstractmethod
-    def set_session(self, endpoint, session):
-        """
-        Store a TLS session for the given endpoint.
-        
-        Args:
-            endpoint: The EndPoint object representing the connection target
-            session: The ssl.SSLSession object to cache
-        """
-        pass
-    
-    @abstractmethod
-    def clear_expired(self):
-        """Remove all expired sessions from the cache."""
-        pass
-    
-    @abstractmethod
-    def clear(self):
-        """Clear all sessions from the cache."""
-        pass
-    
-    @abstractmethod
-    def size(self):
-        """Return the current number of cached sessions."""
-        pass
-
-
-class TLSSessionCacheOptionsBase(ABC):
-    """
-    Abstract base class for TLS session cache configuration options.
-    """
-    
-    @abstractmethod
-    def create_cache(self):
-        """
-        Build and return a TLSSessionCache implementation.
-        
-        Returns:
-            TLSSessionCache: A configured session cache instance
-        """
-        pass
-
-
 class NoHostAvailable(Exception):
     """
     Raised when an operation is attempted but all connections are
@@ -947,29 +879,56 @@ def default_retry_policy(self, policy):
     .. versionadded:: 3.17.0
     """
 
+    tls_session_cache_enabled = True
+    """
+    Enable or disable TLS session caching for faster reconnections.
+    When enabled (default), TLS sessions are cached and reused for subsequent
+    connections to the same endpoint, reducing handshake latency.
+
+    Set to False to disable session caching entirely.
+
+    .. versionadded:: 3.30.0
+    """
+
+    tls_session_cache_size = _DEFAULT_TLS_SESSION_CACHE_SIZE
+    """
+    Maximum number of TLS sessions to cache. Default is 100.
+    When the cache is full, the least recently used session is evicted.
+
+    .. versionadded:: 3.30.0
+    """
+
+    tls_session_cache_ttl = _DEFAULT_TLS_SESSION_CACHE_TTL
+    """
+    Time-to-live for cached TLS sessions in seconds. Default is 3600 (1 hour).
+    Sessions older than this value will not be reused.
+
+    .. versionadded:: 3.30.0
+    """
+
     tls_session_cache_options = None
     """
-    TLS session cache configuration. Set to an instance of :class:`~.TLSSessionCacheOptions`
-    to configure session caching behavior. If None (default), a default configuration will
-    be used when SSL/TLS is enabled.
-    
-    The default configuration caches sessions by host and port, with a maximum of 100 sessions
-    and a TTL of 3600 seconds (1 hour).
-    
-    To disable session caching entirely, set this to False.
-    
+    Advanced TLS session cache configuration. Set to an instance of
+    :class:`~cassandra.tls.TLSSessionCacheOptions` for fine-grained control over
+    session caching behavior (e.g., cache_by_host_only option).
+
+    If None (default), a cache is created using :attr:`~.tls_session_cache_size`
+    and :attr:`~.tls_session_cache_ttl` when SSL/TLS is enabled.
+
+    This option takes precedence over the individual tls_session_cache_* parameters.
+
     Example::
-    
+
         from cassandra.tls import TLSSessionCacheOptions
-        
+
         # Cache by host only (ignoring port)
         options = TLSSessionCacheOptions(
             max_size=200,
             ttl=7200,
             cache_by_host_only=True
         )
         cluster = Cluster(ssl_context=ssl_context, tls_session_cache_options=options)
-    
+
     .. versionadded:: 3.30.0
     """
 
@@ -1302,6 +1261,9 @@ def __init__(self,
                  idle_heartbeat_timeout=30,
                  no_compact=False,
                  ssl_context=None,
+                 tls_session_cache_enabled=True,
+                 tls_session_cache_size=_DEFAULT_TLS_SESSION_CACHE_SIZE,
+                 tls_session_cache_ttl=_DEFAULT_TLS_SESSION_CACHE_TTL,
                  tls_session_cache_options=None,
                  endpoint_factory=None,
                  application_name=None,
@@ -1519,25 +1481,28 @@ def __init__(self,
 
         self.ssl_options = ssl_options
         self.ssl_context = ssl_context
+        self.tls_session_cache_enabled = tls_session_cache_enabled
+        self.tls_session_cache_size = tls_session_cache_size
+        self.tls_session_cache_ttl = tls_session_cache_ttl
         self.tls_session_cache_options = tls_session_cache_options
-        
-        # Initialize TLS session cache if SSL is enabled
+
+        # Initialize TLS session cache if SSL is enabled and caching is enabled
         self._tls_session_cache = None
-        if (ssl_context or ssl_options) and tls_session_cache_options is not False:
+        if (ssl_context or ssl_options) and tls_session_cache_enabled:
             from cassandra.tls import TLSSessionCacheOptions
-            
-            # Use provided options or create default
-            if tls_session_cache_options is None:
+
+            # Use provided options object or create one from individual parameters
+            if tls_session_cache_options is not None:
+                cache_options = tls_session_cache_options
+            else:
                 cache_options = TLSSessionCacheOptions(
-                    max_size=_DEFAULT_TLS_SESSION_CACHE_SIZE,
-                    ttl=_DEFAULT_TLS_SESSION_CACHE_TTL,
+                    max_size=tls_session_cache_size,
+                    ttl=tls_session_cache_ttl,
                     cache_by_host_only=False
                 )
-            else:
-                cache_options = tls_session_cache_options
-            
+
             self._tls_session_cache = cache_options.create_cache()
-        
+
         self.sockopts = sockopts
         self.cql_version = cql_version
         self.max_schema_agreement_wait = max_schema_agreement_wait

cassandra/connection.py

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 from __future__ import absolute_import  # to enable import io from stdlib
-from collections import defaultdict, deque, OrderedDict, namedtuple
+from collections import defaultdict, deque
 import errno
 from functools import wraps, partial, total_ordering
 from heapq import heappush, heappop
@@ -128,7 +128,6 @@ def decompress(byts):
 frame_header_v3 = struct.Struct('>BhBi')
 
 
-
 class EndPoint(object):
     """
     Represents the information to connect to a cassandra node.

cassandra/tls.py

@@ -74,22 +74,6 @@ def size(self):
         pass
 
 
-class TLSSessionCacheOptions(ABC):
-    """
-    Abstract base class for TLS session cache configuration options.
-    """
-    
-    @abstractmethod
-    def create_cache(self):
-        """
-        Build and return a TLSSessionCache implementation.
-        
-        Returns:
-            TLSSessionCache: A configured session cache instance
-        """
-        pass
-
-
 class DefaultTLSSessionCache(TLSSessionCache):
     """
     Default implementation of TLS session caching.