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// Copyright (C) 2018-2022 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef PACKET_QUEUE_H
#define PACKET_QUEUE_H
#include <cc/data.h>
#include <dhcp/socket_info.h>
#include <dhcp/pkt4.h>
#include <dhcp/pkt6.h>
#include <sstream>
namespace isc {
namespace dhcp {
/// @brief Invalid queue parameter exception
///
/// Thrown when packet queue is supplied an invalid/missing parameter
class InvalidQueueParameter : public Exception {
public:
InvalidQueueParameter(const char* file, size_t line, const char* what) :
isc::Exception(file, line, what) {}
};
/// @brief Enumerates choices between the two ends of the queue.
enum class QueueEnd {
FRONT, // Typically the end packets are read from
BACK // Typically the end packets are written to
};
/// @brief Interface for managing a queue of inbound DHCP packets
///
/// This class serves as the abstract interface for packet queue
/// implementations which may be used by @c IfaceMgr to store
/// inbound packets until they are a dequeued for processing.
///
/// @tparam PacketTypePtr Type of packet the queue contains.
/// This expected to be either isc::dhcp::Pkt4Ptr or isc::dhcp::Pkt6Ptr
///
/// @note Derivations of this class MUST BE thread-safe.
template<typename PacketTypePtr>
class PacketQueue {
public:
/// @brief Constructor
///
/// @param queue_type logical name of the queue implementation
/// Typically this is assigned by the factory that creates the
/// queue. It is the logical name used to register queue
/// implementations.
explicit PacketQueue(const std::string& queue_type)
: queue_type_(queue_type) {}
/// Virtual destructor
virtual ~PacketQueue(){};
/// @brief Adds a packet to the queue
///
/// Adds the packet to the queue. Derivations determine
/// which packets to queue and how to queue them.
///
/// @param packet packet to enqueue
/// @param source socket the packet came from
virtual void enqueuePacket(PacketTypePtr packet, const SocketInfo& source) = 0;
/// @brief Dequeues the next packet from the queue
///
/// Dequeues the next packet (if any) and returns it. Derivations determine
/// how packets are dequeued.
///
/// @return A pointer to dequeued packet, or an empty pointer
/// if the queue is empty.
virtual PacketTypePtr dequeuePacket() = 0;
/// @brief return True if the queue is empty.
virtual bool empty() const = 0;
/// @brief Returns the current number of packets in the buffer.
virtual size_t getSize() const = 0;
/// @brief Discards all packets currently in the buffer.
virtual void clear() = 0;
/// @brief Fetches operational information about the current state of
/// the queue
///
/// Creates and returns an ElementPtr containing a single entry,
/// "queue-type". Derivations are expected to call this method first
/// and then add their own values. Since implementations may vary
/// widely on data of interest, this is structured as an ElementPtr
/// for broad latitude.
///
/// @return an ElementPtr containing elements for values of interest
virtual data::ElementPtr getInfo() const {
data::ElementPtr info = data::Element::createMap();
info->set("queue-type", data::Element::create(queue_type_));
return (info);
}
/// @brief Fetches a JSON string representation of queue operational info
///
/// This method calls @c getInfo() and then converts that into JSON text.
///
/// @return string of JSON text
std::string getInfoStr() const {
data::ElementPtr info = getInfo();
std::ostringstream os;
info->toJSON(os);
return (os.str());
}
/// @return Fetches the logical name of the type of this queue.
std::string getQueueType() {
return (queue_type_);
};
private:
/// @brief Logical name of the this queue's implementation type.
std::string queue_type_;
};
/// @brief Defines pointer to the DHCPv4 queue interface used at the application level.
/// This is the type understood by IfaceMgr and the type that should be returned by
/// DHCPv4 packet queue factories.
typedef boost::shared_ptr<PacketQueue<Pkt4Ptr>> PacketQueue4Ptr;
/// @brief Defines pointer to the DHCPv6 queue interface used at the application level.
/// This is the type understood by IfaceMgr and the type that should be returned by
/// DHCPv6 packet queue factories.
typedef boost::shared_ptr<PacketQueue<Pkt6Ptr>> PacketQueue6Ptr;
}; // namespace isc::dhcp
}; // namespace isc
#endif // PACKET_QUEUE_H
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