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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_RING_H
#define PACKET_QUEUE_RING_H
#include <dhcp/packet_queue.h>
#include <boost/circular_buffer.hpp>
#include <boost/scoped_ptr.hpp>
#include <sstream>
#include <mutex>
namespace isc {
namespace dhcp {
/// @brief Provides a ring-buffer implementation of the PacketQueue interface.
///
/// @tparam PacketTypePtr Type of packet the queue contains.
/// This expected to be either isc::dhcp::Pkt4Ptr or isc::dhcp::Pkt6Ptr
template<typename PacketTypePtr>
class PacketQueueRing : public PacketQueue<PacketTypePtr> {
public:
/// @brief Minimum queue capacity permitted. Below five is pretty much
/// nonsensical.
static const size_t MIN_RING_CAPACITY = 5;
/// @brief Constructor
///
/// @param queue_type logical name of the queue implementation
/// @param capacity maximum number of packets the queue can hold
PacketQueueRing(const std::string& queue_type, size_t capacity)
: PacketQueue<PacketTypePtr>(queue_type) {
queue_.set_capacity(capacity);
mutex_.reset(new std::mutex);
}
/// @brief virtual Destructor
virtual ~PacketQueueRing(){};
/// @brief Adds a packet to the queue
///
/// Calls @c shouldDropPacket to determine if the packet should be queued
/// or dropped. If it should be queued it is added to the end of the
/// queue specified by the "to" parameter.
///
/// @param packet packet to enqueue
/// @param source socket the packet came from
virtual void enqueuePacket(PacketTypePtr packet, const SocketInfo& source) {
if (!shouldDropPacket(packet, source)) {
pushPacket(packet);
}
}
/// @brief Dequeues the next packet from the queue
///
/// Dequeues the next packet (if any) and returns it.
///
/// @return A pointer to dequeued packet, or an empty pointer
/// if the queue is empty.
virtual PacketTypePtr dequeuePacket() {
eatPackets(QueueEnd::FRONT);
return (popPacket());
}
/// @brief Determines if a packet should be discarded.
///
/// This function is called in @c enqueuePackets for each packet
/// in its packet list. It provides an opportunity to examine the
/// packet and its source and decide whether it should be dropped
/// or added to the queue. Derivations are expected to provide
/// implementations based on their own requirements. Bear in mind
/// that the packet has NOT been unpacked at this point. The default
/// implementation simply returns false (i.e. keep the packet).
///
/// @return true if the packet should be dropped, false if it should be
/// kept.
virtual bool shouldDropPacket(PacketTypePtr /* packet */,
const SocketInfo& /* source */) {
return (false);
}
/// @brief Discards packets from one end of the queue.
///
/// This function is called at the beginning of @c dequeuePacket and
/// provides an opportunity to examine and discard packets from
/// the queue prior to dequeuing the next packet to be
/// processed. Derivations are expected to provide implementations
/// based on their own requirements. The default implementation is to
/// to simply return without skipping any packets.
///
/// @return The number of packets discarded.
virtual int eatPackets(const QueueEnd& /* from */) {
return (0);
}
/// @brief Pushes a packet onto the queue
///
/// Adds a packet onto the end of queue specified.
///
/// @param packet packet to add to the queue
/// @param to specifies the end of the queue to which the packet
/// should be added.
virtual void pushPacket(PacketTypePtr& packet, const QueueEnd& to=QueueEnd::BACK) {
std::lock_guard<std::mutex> lock(*mutex_);
if (to == QueueEnd::BACK) {
queue_.push_back(packet);
} else {
queue_.push_front(packet);
}
}
/// @brief Pops a packet from the queue
///
/// Removes a packet from the end of the queue specified and returns it.
///
/// @param from specifies the end of the queue from which the packet
/// should be taken. It locks the queue's Mutex upon entry.
///
/// @return A pointer to dequeued packet, or an empty pointer
/// if the queue is empty.
virtual PacketTypePtr popPacket(const QueueEnd& from = QueueEnd::FRONT) {
PacketTypePtr packet;
std::lock_guard<std::mutex> lock(*mutex_);
if (queue_.empty()) {
return (packet);
}
if (from == QueueEnd::FRONT) {
packet = queue_.front();
queue_.pop_front();
} else {
packet = queue_.back();
queue_.pop_back();
}
return (packet);
}
/// @brief Gets the packet currently at one end of the queue
///
/// Returns a pointer the packet at the specified end of the
/// queue without dequeuing it.
///
/// @param from specifies which end of the queue to examine.
///
/// @return A pointer to packet, or an empty pointer if the
/// queue is empty.
virtual const PacketTypePtr peek(const QueueEnd& from=QueueEnd::FRONT) const {
PacketTypePtr packet;
if (!queue_.empty()) {
packet = (from == QueueEnd::FRONT ? queue_.front() : queue_.back());
}
return (packet);
}
/// @brief Returns True if the queue is empty.
virtual bool empty() const {
std::lock_guard<std::mutex> lock(*mutex_);
return (queue_.empty());
}
/// @brief Returns the maximum number of packets allowed in the buffer.
virtual size_t getCapacity() const {
return (queue_.capacity());
}
/// @brief Sets the maximum number of packets allowed in the buffer.
///
/// @todo - do we want to change size on the fly? This might need
/// to be private, called only by constructor
///
/// @throw BadValue if capacity is too low.
virtual void setCapacity(size_t capacity) {
if (capacity < MIN_RING_CAPACITY) {
isc_throw(BadValue, "Queue capacity of " << capacity
<< " is invalid. It must be at least "
<< MIN_RING_CAPACITY);
}
/// @todo should probably throw if it's zero
queue_.set_capacity(capacity);
}
/// @brief Returns the current number of packets in the buffer.
virtual size_t getSize() const {
return (queue_.size());
}
/// @brief Discards all packets currently in the buffer.
virtual void clear() {
queue_.clear();
}
/// @brief Fetches pertinent information
virtual data::ElementPtr getInfo() const {
data::ElementPtr info = PacketQueue<PacketTypePtr>::getInfo();
info->set("capacity", data::Element::create(static_cast<int64_t>(getCapacity())));
info->set("size", data::Element::create(static_cast<int64_t>(getSize())));
return (info);
}
private:
/// @brief Packet queue
boost::circular_buffer<PacketTypePtr> queue_;
/// @brief Mutex for protecting queue accesses.
boost::scoped_ptr<std::mutex> mutex_;
};
/// @brief DHCPv4 packet queue buffer implementation
///
/// This implementation does not (currently) add any drop
/// or packet skip logic, it operates as a verbatim ring
/// queue for DHCPv4 packets.
///
class PacketQueueRing4 : public PacketQueueRing<Pkt4Ptr> {
public:
/// @brief Constructor
///
/// @param queue_type logical name of the queue implementation
/// @param capacity maximum number of packets the queue can hold
PacketQueueRing4(const std::string& queue_type, size_t capacity)
: PacketQueueRing(queue_type, capacity) {
};
/// @brief virtual Destructor
virtual ~PacketQueueRing4(){}
};
/// @brief DHCPv6 packet queue buffer implementation
///
/// This implementation does not (currently) add any drop
/// or packet skip logic, it operates as a verbatim ring
/// queue for DHCPv6 packets.
///
class PacketQueueRing6 : public PacketQueueRing<Pkt6Ptr> {
public:
/// @brief Constructor
///
/// @param queue_type logical name of the queue implementation
/// @param capacity maximum number of packets the queue can hold
PacketQueueRing6(const std::string& queue_type, size_t capacity)
: PacketQueueRing(queue_type, capacity) {
};
/// @brief virtual Destructor
virtual ~PacketQueueRing6(){}
};
}; // namespace isc::dhcp
}; // namespace isc
#endif // PACKET_QUEUE_RING_H
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