Declaration of Garcia-Molina Invitation Leader Election algorithm.

#include <GroupManagement.hpp>

Inheritance diagram for freedm::broker::gm::GMAgent:

Public Types
enum	{ NORMAL, DOWN, RECOVERY, REORGANIZATION, ELECTION }
	Module states. More...

Public Member Functions
	GMAgent ()
	Constructor for using this object as a module. More...

	~GMAgent ()
	Module destructor. More...

int	Run ()
	Called to start the system. More...

Static Public Member Functions
static PeerSet	ProcessPeerList (const PeerListMessage &msg)
	Handles Processing a PeerList. More...

Protected Member Functions
CPeerNode	GetMe ()
	Gets a CPeerNode representing this process. More...

std::string	GetUUID () const
	Gets the UUID of this process. More...

Private Member Functions
ModuleMessage	Accept ()
	Creates an Accept Message. More...

CPeerNode	AddPeer (std::string uuid)
	Adds a peer to the peer set from UUID. More...

CPeerNode	AddPeer (CPeerNode peer)
	Adds a peer from a pointer to a peer node object. More...

ModuleMessage	AreYouCoordinator ()
	Creates AYC Message. More...

ModuleMessage	AreYouCoordinatorResponse (std::string payload, int seq)
	Creates A Response message. More...

ModuleMessage	AreYouThere ()
	Creates a AYT, used for Timeout. More...

ModuleMessage	AreYouThereResponse (std::string payload, int seq)
	Creates A Response message. More...

void	Check (const boost::system::error_code &err)
	Checks for other up leaders. More...

std::string	Coordinator () const
	Returns the coordinators uuid. More...

CPeerNode	GetPeer (const std::string &uuid)
	Gets a pointer to a peer from UUID. More...

int	GetStatus () const
	Gets the status of a node. More...

void	HandleAccept (const AcceptMessage &msg, CPeerNode peer)
	Handles recieving accept messsages. More...

void	HandleAreYouCoordinator (const AreYouCoordinatorMessage &msg, CPeerNode peer)
	Handles recieving are you coordinator messages. More...

void	HandleAreYouThere (const AreYouThereMessage &msg, CPeerNode peer)
	Handles recieving are you there messsages. More...

void	HandleIncomingMessage (boost::shared_ptr< const ModuleMessage > msg, CPeerNode peer)
	Handles received messages. More...

void	HandleInvite (const InviteMessage &msg, CPeerNode peer)
	Handles recieving invite messages. More...

void	HandlePeerList (const PeerListMessage &msg, CPeerNode peer)
	Hadles recieving peerlists. More...

void	HandlePeerListQuery (const PeerListQueryMessage &msg, CPeerNode peer)
	Handles recieving peerlist requests. More...

void	HandleResponseAYC (const AreYouCoordinatorResponseMessage &msg, CPeerNode peer)
	Handles recieving AYC responses. More...

void	HandleResponseAYT (const AreYouThereResponseMessage &msg, CPeerNode peere)
	Handles recieving AYT responses. More...

ModuleMessage	Invitation ()
	Creates Group Invitation Message. More...

void	InviteGroupNodes (const boost::system::error_code &err, PeerSet p_tempSet)
	Sends invitations to all group members. More...

bool	IsCoordinator () const
	Returns true if this node considers itself a coordinator. More...

void	Merge (const boost::system::error_code &err)
	Sends invitations to all known nodes. More...

ModuleMessage	PeerList (std::string requester="all")
	Generates a peer list. More...

void	Premerge (const boost::system::error_code &err)
	Waits a time period determined by UUID for merge. More...

void	PushPeerList ()
	Sends the peer list to all group members. More...

void	Recovery ()
	Resets the algorithm to the default startup state. More...

void	Recovery (const boost::system::error_code &err)
	Handles no response from timeout message. More...

void	Reorganize (const boost::system::error_code &err)
	Puts the system into the working state. More...

void	SetStatus (int status)
	Sets the status of the node. More...

void	StartMonitor (const boost::system::error_code &err)
	Start the monitor after transient is over. More...

void	SystemState ()
	Outputs information about the current state to the logger. More...

void	Timeout (const boost::system::error_code &err)
	Checks that the leader is still alive and working. More...

Static Private Member Functions
static ModuleMessage	PeerListQuery (std::string requester)
	Generates a CMessage that can be used to query for the group. More...

static ModuleMessage	PrepareForSending (const GroupManagementMessage &message, std::string recipient="gm")
	Wraps a GroupManagementMessage in a ModuleMessage. More...

Private Attributes
boost::posix_time::time_duration	AYC_RESPONSE_TIMEOUT
	How long to wait for responses from other nodes. More...

boost::posix_time::time_duration	AYT_RESPONSE_TIMEOUT
	How long to wait for responses from other nodes. More...

boost::posix_time::time_duration	CHECK_TIMEOUT
	How long between AYC checks. More...

boost::posix_time::time_duration	FID_TIMEOUT
	How long to wait before checking attached FIDs. More...

boost::posix_time::time_duration	INVITE_RESPONSE_TIMEOUT
	How long to wait for responses from other nodes. More...

TimedPeerSet	m_AYCResponse
	Nodes expecting AYC response from. More...

TimedPeerSet	m_AYTResponse
	Nodes expecting AYT response from. More...

PeerSet	m_Coordinators
	Known Coordinators. More...

std::map< std::string, bool >	m_fidstate
	A store for the state of attached FIDs. More...

CBroker::TimerHandle	m_fidtimer
	Timer for checking FIDs. More...

google::protobuf::uint32	m_GroupID
	The ID number of the current group (Never initialized for fun) More...

std::string	m_GroupLeader
	The uuid of the group leader. More...

int	m_groupsbroken
	Number of groups broken. More...

int	m_groupselection
	Number of elections started. More...

int	m_groupsformed
	Number of groups formed. More...

int	m_groupsjoined
	Number of accepts sent. More...

unsigned int	m_GrpCounter
	The number of groups being formed. More...

boost::asio::io_service	m_localservice
	The io_service used. More...

int	m_membership
	Total size of groups after all checks. More...

int	m_membershipchecks
	Number of membership checks. More...

int	m_status
	A store for the status of this node. More...

CBroker::TimerHandle	m_timer
	A timer for stepping through the election process. More...

PeerSet	m_UpNodes
	Nodes In My Group. More...

boost::posix_time::time_duration	TIMEOUT_TIMEOUT
	How long beteween AYT checks. More...

Member Enumeration Documentation

anonymous enum

Enumerator
NORMAL
DOWN
RECOVERY
REORGANIZATION
ELECTION

Constructor & Destructor Documentation

freedm::broker::gm::GMAgent::GMAgent ( )

GMAgent::GMAgent

Description:: Constructor for the group management module.

Limitations:: None

Precondition:: None

Postcondition:: Object initialized and ready to enter run state.

freedm::broker::gm::GMAgent::~GMAgent ( )

GMAgent::~GMAgent

Description:: Class desctructor

Precondition:: None

Postcondition:: The object is ready to be destroyed.

Member Function Documentation

ModuleMessage freedm::broker::gm::GMAgent::Accept ( )

private

GMAgent::Accept

Description:: Creates a new accept message from this node

Precondition:: This node is in a group.

Postcondition:: No change.

Returns: A GroupManagementMessage with the contents of an Accept message

CPeerNode freedm::broker::gm::GMAgent::AddPeer ( std::string uuid )

private

GMAgent::AddPeer

Description:: Adds a peer to allpeers by uuid.

Precondition:: the UUID is registered in the connection manager

Postcondition:: A new peer object is created and inserted in CGlobalPeerList::instance().

Returns: A pointer to the new peer

Parameters

uuid	of the peer to add.

CPeerNode freedm::broker::gm::GMAgent::AddPeer ( CPeerNode peer )

private

GMAgent::AddPeer

Description:: Adds a peer to all peers by pointer.

Precondition:: the pointer is valid

Postcondition:: The peer object is inserted in CGlobalPeerList::instance().

Returns: A pointer that is the same as the input pointer

Parameters

peer	a pointer to a peer.

ModuleMessage freedm::broker::gm::GMAgent::AreYouCoordinator ( )

private

GMAgent::AreYouCoordinator

Description:: Creates a new Are You Coordinator message, from this object

Precondition:: The UUID is set

Postcondition:: No change

Returns: A GroupManagementMessage with the contents of an Are You Coordinator Message.

Limitations:: : Can only author messages from this node.

ModuleMessage freedm::broker::gm::GMAgent::AreYouCoordinatorResponse	(	std::string	payload,
		int	seq
	)

private

GMAgent::AreYouCoordinatorResponse

Description:: Creates a response message (Yes/No) message from this node

Precondition:: This node has a UUID.

Postcondition:: No change.

Parameters

payload	Response message (typically yes or no)
seq	sequence number? (?)

Returns: A GroupManagementMessage with the contents of a Response message

ModuleMessage freedm::broker::gm::GMAgent::AreYouThere ( )

private

GMAgent::AreYouThere

Description:: Creates a new AreYouThere message from this node

Precondition:: This node is in a group.

Postcondition:: No Change.

Returns: A GroupManagementMessage with the contents of an AreYouThere message

ModuleMessage freedm::broker::gm::GMAgent::AreYouThereResponse	(	std::string	payload,
		int	seq
	)

private

GMAgent::AreYouThereResponse

Description:: Creates a response message (Yes/No) message from this node

Precondition:: This node has a UUID.

Postcondition:: No change.

Parameters

payload	Response message (typically yes or no)
seq	sequence number? (?)

Returns: A GroupManagementMessage with the contents of a Response message

void freedm::broker::gm::GMAgent::Check ( const boost::system::error_code & err )

private

GMAgent::Check

Description:: This method queries all nodes to Check and see if any of them consider themselves to be Coordinators.

Precondition:: This node is in the normal state.

Postcondition:: Output of a system state and sent messages to all nodes to Check for Coordinators.

Parameters

err	Error associated with calling timer.

Citation:: GroupManagement (Check).

std::string freedm::broker::gm::GMAgent::Coordinator ( ) const

inlineprivate

CPeerNode IDGIModule::GetMe ( )

protectedinherited

GetMe

Description:: Gets a CPeerNode that refers to this process.

Returns: A CPeerNode referring to this process.

CPeerNode freedm::broker::gm::GMAgent::GetPeer ( const std::string & uuid )

private

GMAgent::GetPeer

Description:: Gets a peer from All Peers by uuid

Precondition:: None

Postcondition:: None

Parameters

uuid	The uuid of the peer to fetch

Returns: A pointer to the requested peer, or a null pointer if the peer could not be found.

int freedm::broker::gm::GMAgent::GetStatus ( ) const

private

Description:: returns the status stored in the node as an an integer. This means that in an inherited class, you may either define integer constants or an enumeration to generate status values.

std::string IDGIModule::GetUUID ( ) const

protectedinherited

GetUUID

Description:: Gets this process's UUID.

Returns: This process's UUID

void freedm::broker::gm::GMAgent::HandleAccept	(	const AcceptMessage &	msg,
		CPeerNode	peer
	)

private

GMAgent::HandleAccept

Description:: Handles receiveing the invite accept

Key:: gm.Accept

Precondition:: In an election, and invites have been sent out.

Postcondition:: The sender is added to the tenative list of accepted peers for the group, if the accept messag is for the correct group identifier.

Interaction Peers:: Any node which has received an invite. (This can be any selection of the global peerlist, not just the ones this specific node sent the message to.)

void freedm::broker::gm::GMAgent::HandleAreYouCoordinator	(	const AreYouCoordinatorMessage &	msg,
		CPeerNode	peer
	)

private

GMAgent::HandleAreYouCoordinator

Description:: Handles receiveing the AYC message

Key:: gm.AreYouCoordinator

Precondition:: None

Postcondition:: The node responds yes or no to the request.

Interaction Peers:: Any node in the system is eligible to receive this at any time.

void freedm::broker::gm::GMAgent::HandleAreYouThere	(	const AreYouThereMessage &	msg,
		CPeerNode	peer
	)

private

GMAgent::HandleAreYouThere

Description:: Handles recieving the AYT message

Key:: gm.AreYouThere

Precondition:: None

Postcondition:: The node responds yes or no to the request.

Interaction Peers:: Any node in the system is eligible to receive this message at any time.

void freedm::broker::gm::GMAgent::HandleIncomingMessage	(	boost::shared_ptr< const ModuleMessage >	msg,
		CPeerNode	peer
	)

privatevirtual

"Downcasts" incoming messages into a specific message type, and passes the message to an appropriate handler.

Parameters

msg	the incoming message
peer	the node that sent this message (could be this DGI)

Implements freedm::broker::IDGIModule.

void freedm::broker::gm::GMAgent::HandleInvite	(	const InviteMessage &	msg,
		CPeerNode	peer
	)

private

GMAgent::HandleInvite

Description:: Handles recieving the invite

Key:: gm.Invite

Precondition:: The system is in the NORMAL state

Postcondition:: The system updates its group to accept the invite and switches to reorganization mode; it will wait for a timeout. If the Ready/Peerlist has not arrived, it will enter recovery. Otherwise, it will resume work as part of the group it was invited to.

Interaction Peers:: Any node could send an invite at any time.

void freedm::broker::gm::GMAgent::HandlePeerList	(	const PeerListMessage &	msg,
		CPeerNode	peer
	)

private

GMAgent::HandlePeerList

Description:: Handles receiveing the peerlist.

Key:: any.PeerList

Precondition:: The node is in the reorganization or normal state

Postcondition:: The node's peerlist is updated to match that of the incoming message if the message has come from his coordinator.

Interaction Peers:: Coordinator only.

void freedm::broker::gm::GMAgent::HandlePeerListQuery	(	const PeerListQueryMessage &	msg,
		CPeerNode	peer
	)

private

GMAgent::HandlePeerListQuery

Description:: Handles responding to peerlist queries.

Key:: gm.PeerListQuery

Precondition:: None

Postcondition:: Dispatched a message to the requester with a peerlist.

Interaction Peers:: Any. (Local or remote, doesn't have to be a member of group)

void freedm::broker::gm::GMAgent::HandleResponseAYC	(	const AreYouCoordinatorResponseMessage &	msg,
		CPeerNode	peer
	)

private

GMAgent::HandleResponseAYC

Description:: Handles recieving the Response

Key:: gm.Response.AreYouCoordinator

Precondition:: The timer for the AYC request batch the original request was a part of has not expired

Postcondition:: The response from the sender is noted, if yes, the groups will attempt to merge in the future.

Interaction Peers:: A node the AYC request was sent to.

void freedm::broker::gm::GMAgent::HandleResponseAYT	(	const AreYouThereResponseMessage &	msg,
		CPeerNode	peer
	)

private

GMAgent::HandleResponseAYT

Description:: Handles recieving the Response

Key:: gm.Response.AreYouThere

Precondition:: The timer for the AYT request batch (typically 1) the original request was a part of has not expired

Postcondition:: The response from the sender is noted. If the answer is no, then this node will enter recovery, if the recovery timer has not already been set, otherwise we will allow it to expire.

ModuleMessage freedm::broker::gm::GMAgent::Invitation ( )

private

GMAgent::Invitation

Description:: Creates a new invation message from the leader of this node's current leader, to join this group.

Precondition:: The node is currently in a group.

Postcondition:: No change

Returns: A GroupManagementMessage with the contents of a Invitation message.

void freedm::broker::gm::GMAgent::InviteGroupNodes	(	const boost::system::error_code &	err,
		PeerSet	p_tempSet
	)

private

GMAgent::InviteGroupNodes

Description:: This function will invite all the members of a node's old group to join it's new group.

Precondition:: None

Postcondition:: Invitations have been sent to members of this node's old group. if this node is a Coordinator, this node sets a timer for Reorganize

Parameters

err	The error message associated with the calling thimer
p_tempSet	The set of nodes that were members of the old group.

Citation:: Group Management (Merge)

bool freedm::broker::gm::GMAgent::IsCoordinator ( ) const

inlineprivate

void freedm::broker::gm::GMAgent::Merge ( const boost::system::error_code & err )

private

GMAgent::Merge

Description:: If this node is a Coordinator, this method sends invites to join this node's group to all Coordinators, and then makes a call to second function to invite all current members of this node's old group to the new group.

Precondition:: This node has waited for a Premerge.

Postcondition:: If this node was a Coordinator, this node has been placed in an election state. Additionally, invitations have been sent to all Coordinators this node is aware of. Lastly, this function has called a function or set a timer to invite its old group nodes.

Parameters

err	A error associated with the calling timer.

Citation:: Group Management (Merge)

ModuleMessage freedm::broker::gm::GMAgent::PeerList ( std::string requester = "all" )

private

GMAgent::PeerList

Description:: Packs the group list (Up_Nodes) in GroupManagementMessage

Precondition:: This node is a leader.

Postcondition:: No Change.

Returns: A GroupManagementMessage with the contents of group membership

ModuleMessage freedm::broker::gm::GMAgent::PeerListQuery ( std::string requester )

staticprivate

GMAgent::PeerListQuery

Description:: Generates a GroupManagementMessage that can be used to query the peerlist of a node.

Precondition:: : None

Postcondition:: : No change

Parameters

requester The module who the response should be addressed to.

Returns: A GroupManagementMessage which can be used to query for

void freedm::broker::gm::GMAgent::Premerge ( const boost::system::error_code & err )

private

GMAgent::Premerge

Description:: Handles a proportional wait prior to calling Merge

Precondition:: Check has been called and responses have been collected from other nodes. This node is a Coordinator.

Postcondition:: A timer has been set based on this node's UUID to break up ties before merging.

Parameters

err	An error associated with the clling timer.

Citation:: GroupManagement (Merge)

ModuleMessage freedm::broker::gm::GMAgent::PrepareForSending	(	const GroupManagementMessage &	message,
		std::string	recipient = `"gm"`
	)

staticprivate

Wraps a GroupManagementMessage in a ModuleMessage.

Parameters

message	the message to prepare. If any required field is unset, the DGI will abort.
recipient	the module (sc/lb/gm/clk etc.) the message should be delivered to

Returns: a ModuleMessage containing a copy of the GroupManagementMessage

PeerSet freedm::broker::gm::GMAgent::ProcessPeerList ( const PeerListMessage & msg )

static

GMAgent::ProcessPeerList

Description:: Provides a utility function for correctly handling incoming peer lists.

Parameters

msg	The message to parse

Returns: A PeerSet with all nodes in the group.

void freedm::broker::gm::GMAgent::PushPeerList ( )

private

GMAgent::PushPeerList

Description:: Sends the membership list to other modules of this node and other nodes

Precondition:: This node is new group leader

Postcondition:: A peer list is pushed to the group members

Returns: Nothing

void freedm::broker::gm::GMAgent::Recovery ( )

private

GMAgent::Recovery

Description:: The method used to set or reset a node into a "solo" state where it is its own leader. To do this, it forms an empty group, then enters a normal state.

Precondition:: None

Postcondition:: The node enters a NORMAL state.

Citation:: Group Management Algorithmn (Recovery).

void freedm::broker::gm::GMAgent::Recovery ( const boost::system::error_code & err )

private

GMAgent::Recovery

Description:: Recovery function extension for handling timer expirations.

Precondition:: Some timer leading to this function has expired or been canceled.

Postcondition:: If the timer has expired, Recovery begins, if the timer was canceled and this node is NOT a Coordinator, this will cause a Timeout Check using Timeout()

Parameters

err	The error code associated with the calling timer.

void freedm::broker::gm::GMAgent::Reorganize ( const boost::system::error_code & err )

private

GMAgent::Reorganize

Description:: Organizes the members of the group and prepares them to do their much needed work!

Precondition:: The node is a leader of group.

Postcondition:: The group has received work assignments, ready messages have been sent out, and this node enters the NORMAL state.

Citation:: Group Management Reorganize

int freedm::broker::gm::GMAgent::Run ( )

GMAgent::Run

Description:: Main function which initiates the algorithm

Precondition:: connections to peers should be instantiated

Postcondition:: execution of group management algorithm

void freedm::broker::gm::GMAgent::SetStatus ( int status )

private

Description:: Sets the internal status variable, m_status based on the paramter status. See GetStatus for tips on establishing the status code numbers.

Parameters

status The status code to set

Precondition:: None

Postcondition:: The modules status code has been set to "status"

void freedm::broker::gm::GMAgent::StartMonitor ( const boost::system::error_code & err )

private

void freedm::broker::gm::GMAgent::SystemState ( )

private

GMAgent::SystemState

Description:: Puts the system state to the logger.

Precondition:: None

Postcondition:: None

void freedm::broker::gm::GMAgent::Timeout ( const boost::system::error_code & err )

private

GMAgent::Timeout

Description:: Sends an AreYouThere message to the coordinator and sets a timer if the timer expires, this node goes into recovery.

Precondition:: The node is a member of a group, but not the leader

Postcondition:: A timer for recovery is set.

Citation:: Group Managment Timeout

Member Data Documentation

boost::posix_time::time_duration freedm::broker::gm::GMAgent::AYC_RESPONSE_TIMEOUT

private

boost::posix_time::time_duration freedm::broker::gm::GMAgent::AYT_RESPONSE_TIMEOUT

private

boost::posix_time::time_duration freedm::broker::gm::GMAgent::CHECK_TIMEOUT

private

boost::posix_time::time_duration freedm::broker::gm::GMAgent::FID_TIMEOUT

private

boost::posix_time::time_duration freedm::broker::gm::GMAgent::INVITE_RESPONSE_TIMEOUT

private

TimedPeerSet freedm::broker::gm::GMAgent::m_AYCResponse

private

TimedPeerSet freedm::broker::gm::GMAgent::m_AYTResponse

private

PeerSet freedm::broker::gm::GMAgent::m_Coordinators

private

std::map< std::string , bool > freedm::broker::gm::GMAgent::m_fidstate

private

CBroker::TimerHandle freedm::broker::gm::GMAgent::m_fidtimer

private

google::protobuf::uint32 freedm::broker::gm::GMAgent::m_GroupID

private

std::string freedm::broker::gm::GMAgent::m_GroupLeader

private

int freedm::broker::gm::GMAgent::m_groupsbroken

private

int freedm::broker::gm::GMAgent::m_groupselection

private

int freedm::broker::gm::GMAgent::m_groupsformed

private

int freedm::broker::gm::GMAgent::m_groupsjoined

private

unsigned int freedm::broker::gm::GMAgent::m_GrpCounter

private

boost::asio::io_service freedm::broker::gm::GMAgent::m_localservice

private

int freedm::broker::gm::GMAgent::m_membership

private

int freedm::broker::gm::GMAgent::m_membershipchecks

private

int freedm::broker::gm::GMAgent::m_status

private

CBroker::TimerHandle freedm::broker::gm::GMAgent::m_timer

private

PeerSet freedm::broker::gm::GMAgent::m_UpNodes

private

boost::posix_time::time_duration freedm::broker::gm::GMAgent::TIMEOUT_TIMEOUT

private

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

/home/docs/checkouts/readthedocs.org/user_builds/freedm/checkouts/stable/Broker/src/gm/GroupManagement.hpp
/home/docs/checkouts/readthedocs.org/user_builds/freedm/checkouts/stable/Broker/src/gm/GroupManagement.cpp

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Private Member Functions

Static Private Member Functions

Private Attributes

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation