1 files changed, 108 insertions, 0 deletions
diff --git a/src/lib/dhcpsrv/flq_allocation_state.h b/src/lib/dhcpsrv/flq_allocation_state.h
new file mode 100644
index 0000000..194edcf
--- /dev/null
+++ b/src/lib/dhcpsrv/flq_allocation_state.h
@@ -0,0 +1,108 @@
+// Copyright (C) 2023 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 FLQ_ALLOCATION_STATE_H
+#define FLQ_ALLOCATION_STATE_H
+
+#include <dhcpsrv/allocation_state.h>
+#include <dhcpsrv/pool.h>
+#include <dhcpsrv/subnet.h>
+#include <boost/shared_ptr.hpp>
+#include <cstdint>
+
+namespace isc {
+namespace dhcp {
+
+/// @brief Forward declaration of the @c PoolFreeLeaseQueueAllocationState.
+class PoolFreeLeaseQueueAllocationState;
+
+/// @brief Type of the pointer to the @c PoolFreeLeaseQueueAllocationState.
+typedef boost::shared_ptr<PoolFreeLeaseQueueAllocationState> PoolFreeLeaseQueueAllocationStatePtr;
+
+/// @brief Pool allocation state used by the FLQ allocator.
+class PoolFreeLeaseQueueAllocationState : public AllocationState {
+public:
+
+    /// @brief Factory function creating the state instance from a pool.
+    ///
+    /// @param pool instance of the pool for which the allocation state
+    /// should be instantiated.
+    /// @return new allocation state instance.
+    static PoolFreeLeaseQueueAllocationStatePtr create(const PoolPtr& pool);
+
+    /// @brief Constructor.
+    ///
+    /// Instantiates the allocation state for the specified lease type.
+    ///
+    /// @param type lease type.
+    PoolFreeLeaseQueueAllocationState(Lease::Type type);
+
+    /// @brief Checks if the pool has run out of free leases.
+    ///
+    /// @return true if the pool has no free leases, false otherwise.
+    bool exhausted() const;
+
+    /// @brief Adds a free lease to the queue.
+    ///
+    /// @param address lease address.
+    void addFreeLease(const asiolink::IOAddress& address);
+
+    /// @brief Deletes free lease from the queue.
+    ///
+    /// @param address lease address.
+    void deleteFreeLease(const asiolink::IOAddress& address);
+
+    /// @brief Returns next available lease.
+    ///
+    /// @return next free lease address or IPv4/IPv6 zero address when
+    /// there are no free leases.
+    asiolink::IOAddress offerFreeLease();
+
+    /// @brief Returns the current number of free leases in the queue.
+    ///
+    /// @return the number of free leases in the queue.
+    size_t getFreeLeaseCount() const;
+
+private:
+
+    /// @brief A multi-index container holding free leases.
+    ///
+    /// When it is used as a storage for IPv4 leases, the @c AddressType
+    /// should be @c uint32_t. For IPv6 leases, it should be @c IOAddress.
+    /// Note that using the @c uint32_t for the IPv4 case significantly reduces
+    /// the amount of memory occupied by the container by removing the overhead
+    /// of holding the entire IOAddress instance.
+    template<typename AddressType>
+    using FreeLeaseQueue = boost::multi_index_container<
+        AddressType,
+        boost::multi_index::indexed_by<
+            boost::multi_index::sequenced<>,
+            boost::multi_index::hashed_unique<
+                boost::multi_index::identity<AddressType>
+            >
+        >
+    >;
+
+    /// @brief A multi-index container holding free IPv4 leases.
+    typedef boost::shared_ptr<FreeLeaseQueue<uint32_t>> FreeLease4QueuePtr;
+
+    /// @brief A multi-index container holding free IPv6 leases.
+    typedef boost::shared_ptr<FreeLeaseQueue<asiolink::IOAddress>> FreeLease6QueuePtr;
+
+    /// @brief An instance of the multi-index container holding
+    /// free IPv4 leases.
+    FreeLease4QueuePtr free_lease4_queue_;
+
+    /// @brief An instance of the multi-index container holding
+    /// free IPv6 leases.
+    FreeLease6QueuePtr free_lease6_queue_;
+};
+
+
+} // end of isc::dhcp namespace
+} // end of isc namespace
+
+#endif // FLQ_ALLOCATION_STATE_H