isc::dhcp::FreeLeaseQueueAllocator Class Reference

An allocator maintaining a queue of free leases. More...

#include <flq_allocator.h>

Inheritance diagram for isc::dhcp::FreeLeaseQueueAllocator:

Public Member Functions
	FreeLeaseQueueAllocator (Lease::Type type, const WeakSubnetPtr &subnet)
	Constructor.
virtual std::string	getType () const
	Returns the allocator type string.
Public Member Functions inherited from isc::dhcp::Allocator
	Allocator (Lease::Type type, const WeakSubnetPtr &subnet)
	Constructor.
virtual	~Allocator ()
	Virtual destructor.
void	initAfterConfigure ()
	Performs allocator initialization after server's reconfiguration.
virtual isc::asiolink::IOAddress	pickAddress (const ClientClasses &client_classes, const IdentifierBaseTypePtr &duid, const asiolink::IOAddress &hint)
	Picks an address.
virtual isc::asiolink::IOAddress	pickPrefix (const ClientClasses &client_classes, Pool6Ptr &pool, const IdentifierBaseTypePtr &duid, PrefixLenMatchType prefix_length_match, const asiolink::IOAddress &hint, uint8_t hint_prefix_length)
	Picks a delegated prefix.

Additional Inherited Members
Public Types inherited from isc::dhcp::Allocator
enum	PrefixLenMatchType { PREFIX_LEN_EQUAL , PREFIX_LEN_LOWER , PREFIX_LEN_HIGHER }
	Type of preferred PD-pool prefix length selection criteria. More...
Static Public Member Functions inherited from isc::dhcp::Allocator
static bool	isValidPrefixPool (Allocator::PrefixLenMatchType prefix_length_match, PoolPtr pool, uint8_t hint_prefix_length)
	Check if the pool matches the selection criteria relative to the provided hint prefix length.
Protected Member Functions inherited from isc::dhcp::Allocator
Protected Attributes inherited from isc::dhcp::Allocator
bool	inited_
	Indicates if the allocator has been initialized.
std::mutex	mutex_
	The mutex to protect the allocated lease.
Lease::Type	pool_type_
	Defines pool type allocation.
WeakSubnetPtr	subnet_
	Weak pointer to the subnet owning the allocator.
SubnetID	subnet_id_
	ID of a subnet to which the allocator belongs.

Detailed Description

An allocator maintaining a queue of free leases.

This allocator populates the queue of free leases during the initialization. It also installs the callbacks in the LeaseMgr, to track the subsequent lease changes. It allows for maintaining the running queue of free leases.

The allocator offers the leases from the queue, minimizing the number of the allocation engine's attempts to check if some other client is using the offered lease. Ideally, only one check should suffice. However, when several servers share a lease database, the collisions may occur because the servers don't observe each others' allocations.

This allocator should only be used for reasonably small pools due to the overhead to populate the free leases. A reasonably small pool is an IPv4 pool (including /8) and the prefix delegation pools with similar capacity. This allocator is not suitable for a typical IPv6 address pool (e.g., /64). An attempt to populate free leases for such a giant pool would freeze the server and likely exhaust its memory.

Free leases are populated in a random order.

Definition at line 38 of file flq_allocator.h.

Constructor & Destructor Documentation

FreeLeaseQueueAllocator()

isc::dhcp::FreeLeaseQueueAllocator::FreeLeaseQueueAllocator	(	Lease::Type	type,
		const WeakSubnetPtr &	subnet )

Constructor.

Parameters

type	specifies the type of allocated leases.
subnet	weak pointer to the subnet owning the allocator.

Definition at line 31 of file flq_allocator.cc.

Member Function Documentation

getType()

virtual std::string isc::dhcp::FreeLeaseQueueAllocator::getType ( ) const

inlinevirtual

Returns the allocator type string.

Returns

flq string.

Implements isc::dhcp::Allocator.

Definition at line 50 of file flq_allocator.h.

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The documentation for this class was generated from the following files:

• flq_allocator.h
• flq_allocator.cc