Line data    Source code

       1             : #pragma once
       2             : 
       3             : #include "envoy/network/listen_socket.h"
       4             : 
       5             : namespace Envoy {
       6             : namespace Network {
       7             : 
       8             : /**
       9             :  * A connection handler that is balanced. Typically implemented by individual listeners depending
      10             :  * on their balancing configuration.
      11             :  */
      12             : class BalancedConnectionHandler {
      13             : public:
      14         607 :   virtual ~BalancedConnectionHandler() = default;
      15             : 
      16             :   /**
      17             :    * @return the number of active connections within the handler.
      18             :    */
      19             :   virtual uint64_t numConnections() const PURE;
      20             : 
      21             :   /**
      22             :    * Increment the number of connections within the handler. This must be called by a connection
      23             :    * balancer implementation prior to a connection being picked via pickTargetHandler(). This makes
      24             :    * sure that connection counts are accurate during connection transfer (i.e., that the target
      25             :    * balancer accounts for the incoming connection). This is done by the balancer vs. the
      26             :    * connection handler to account for different locking needs inside the balancer.
      27             :    */
      28             :   virtual void incNumConnections() PURE;
      29             : 
      30             :   /**
      31             :    * Post a connected socket to this connection handler. This is used for cross-thread connection
      32             :    * transfer during the balancing process.
      33             :    */
      34             :   virtual void post(Network::ConnectionSocketPtr&& socket) PURE;
      35             : 
      36             :   virtual void onAcceptWorker(Network::ConnectionSocketPtr&& socket,
      37             :                               bool hand_off_restored_destination_connections, bool rebalanced) PURE;
      38             : };
      39             : 
      40             : /**
      41             :  * An implementation of a connection balancer. This abstracts the underlying policy (e.g., exact,
      42             :  * fuzzy, etc.).
      43             :  */
      44             : class ConnectionBalancer {
      45             : public:
      46         622 :   virtual ~ConnectionBalancer() = default;
      47             : 
      48             :   /**
      49             :    * Register a new handler with the balancer that is available for balancing.
      50             :    */
      51             :   virtual void registerHandler(BalancedConnectionHandler& handler) PURE;
      52             : 
      53             :   /**
      54             :    * Unregister a handler with the balancer that is no longer available for balancing.
      55             :    */
      56             :   virtual void unregisterHandler(BalancedConnectionHandler& handler) PURE;
      57             : 
      58             :   /**
      59             :    * Pick a target handler to send a connection to.
      60             :    * @param current_handler supplies the currently executing connection handler.
      61             :    * @return current_handler if the connection should stay bound to the current handler, or a
      62             :    *         different handler if the connection should be rebalanced.
      63             :    *
      64             :    * NOTE: It is the responsibility of the balancer to call incNumConnections() on the returned
      65             :    *       balancer. See the comments above for more explanation.
      66             :    */
      67             :   virtual BalancedConnectionHandler&
      68             :   pickTargetHandler(BalancedConnectionHandler& current_handler) PURE;
      69             : };
      70             : 
      71             : using ConnectionBalancerSharedPtr = std::shared_ptr<ConnectionBalancer>;
      72             : using BalancedConnectionHandlerOptRef =
      73             :     absl::optional<std::reference_wrapper<BalancedConnectionHandler>>;
      74             : 
      75             : } // namespace Network
      76             : } // namespace Envoy