Implement an event-based simulator for QuicConnection

net/quic/core/congestion_control/simulation/switch.h

+#ifndef NET_QUIC_CORE_CONGESTION_CONTROL_SIMULATION_SWITCH_H_
+#define NET_QUIC_CORE_CONGESTION_CONTROL_SIMULATION_SWITCH_H_
+
+#include <unordered_map>
+
+#include "net/quic/core/congestion_control/simulation/queue.h"
+
+namespace net {
+namespace simulation {
+
+typedef size_t SwitchPortNumber;
+
+// Simulates a network switch with simple persistent learning scheme and queues
+// on every output port.
+class Switch {
+ public:
+  Switch(Simulator* simulator,
+         std::std::string name,
+         SwitchPortNumber port_count,
+         QuicByteCount queue_capacity);
+
+  // Returns Endpoint associated with the port under number |port_number|.  Just
+  // like on most real switches, port numbering starts with 1.
+  inline Endpoint* port(SwitchPortNumber port_number) {
+    DCHECK_NE(port_number, 0);
+    return &ports_[port_number - 1];
+  }
+
+ private:
+  class Port : public Endpoint, public UnconstrainedPortInterface {
+   public:
+    Port(Simulator* simulator,
+         std::std::string name,
+         Switch* parent,
+         SwitchPortNumber port_number,
+         QuicByteCount queue_capacity);
+    Port(Port&&) = delete;
+    ~Port() override {}
+
+    // Accepts packet to be routed into the switch.
+    void AcceptPacket(std::unique_ptr<Packet> packet) override;
+    // Enqueue packet to be routed out of the switch.
+    void EnqueuePacket(std::unique_ptr<Packet> packet);
+
+    UnconstrainedPortInterface* GetRxPort() override;
+    void SetTxPort(ConstrainedPortInterface* port) override;
+
+    void Act() override;
+
+    inline bool connected() { return connected_; }
+
+   private:
+    Switch* parent_;
+    SwitchPortNumber port_number_;
+    bool connected_;
+
+    Queue queue_;
+
+    DISALLOW_COPY_AND_ASSIGN(Port);
+  };
+
+  // Sends the packet to the appropriate port, or to all ports if the
+  // appropriate port is not known.
+  void DispatchPacket(SwitchPortNumber port_number,
+                      std::unique_ptr<Packet> packet);
+
+  std::deque<Port> ports_;
+  std::unordered_map<std::std::string, Port*> switching_table_;
+
+  DISALLOW_COPY_AND_ASSIGN(Switch);
+};
+
+}  // namespace simulation
+}  // namespace net
+
+#endif  // NET_QUIC_CORE_CONGESTION_CONTROL_SIMULATION_SWITCH_H_