RewindQueue Class Reference

Public Member Functions
	RewindQueue ()
	The RewindQueue stores one TimeStepInfo for each time step done.
	~RewindQueue ()
	Frees all saved state information.
void	reset ()
	Frees all saved state information and all destroyable rewinder.
void	addLocalEvent (EventRewinder *event_rewinder, BareNetworkString *buffer, bool confirmed, int ticks)
	Adds an event to the rewind data.
void	addLocalState (BareNetworkString *buffer, bool confirmed, int ticks)
	Adds a state from the local simulation to the last created TimeStepInfo container with the current world time.
void	addNetworkEvent (EventRewinder *event_rewinder, BareNetworkString *buffer, int ticks)
	Adds an event to the list of network rewind data.
void	addNetworkState (BareNetworkString *buffer, int ticks)
	Adds a state to the list of network rewind data.
void	addNetworkRewindInfo (RewindInfo *ri)
void	mergeNetworkData (int world_ticks, bool *needs_rewind, int *rewind_ticks)
	Merges thread-safe all data received from the network up to and including the current time (tick) with the current local rewind information.
void	replayAllEvents (int ticks)
	Replays all events (not states) that happened at the specified time.
bool	isEmpty () const
bool	hasMoreRewindInfo () const
	Returns true if there is at least one more RewindInfo available.
int	undoUntil (int undo_ticks)
	Rewinds the rewind queue and undos all events/states stored.
void	insertRewindInfo (RewindInfo *ri)
	Inserts a RewindInfo object in the list of all events at the correct time.
int	getLatestConfirmedState () const
	Returns the time of the latest confirmed state.
void	next ()
	Sets the current element to be the next one and returns the next RewindInfo element.
RewindInfo *	getCurrent ()
	Returns the current RewindInfo.

Static Public Member Functions
static void	unitTesting ()
	Unit tests for RewindQueue.

Private Types
typedef std::list< RewindInfo * >	AllRewindInfo
typedef std::vector< RewindInfo * >	AllNetworkRewindInfo
	The list of all events received from the network.

Private Member Functions
void	cleanupOldRewindInfo (int ticks)
	Deletes all states and event before the given time.

Private Attributes
AllRewindInfo	m_all_rewind_info
Synchronised< AllNetworkRewindInfo >	m_network_events
AllRewindInfo::iterator	m_current
	Iterator to the curren time step info to be handled.
int	m_latest_confirmed_state_time
	Time at which the latest confirmed state is at.

Member Typedef Documentation

AllNetworkRewindInfo

typedef std::vector<RewindInfo*> RewindQueue::AllNetworkRewindInfo

private

The list of all events received from the network.

They are stored in a separate thread (so this data structure is thread-save), and merged into m_rewind_info from the main thread. This design (as opposed to locking m_rewind_info) reduces the synchronisation between main thread and network thread.

Constructor & Destructor Documentation

RewindQueue()

RewindQueue::RewindQueue

(

)

The RewindQueue stores one TimeStepInfo for each time step done.

The TimeStepInfo stores all states and events to be used at the given timestep. All network events (i.e. new states or client events) are stored in a separate list m_network_events. At the very start of a new time step a new TimeStepInfo object is added. Then all network events that are supposed to happen between t and t+dt are added to this newly added TimeStep (see mergeNetworkData), and are then being executed. In case of a rewind the RewindQueue finds the last TimeStepInfo with a confirmed server state (undoing the events, see undoUntil). Then the state is restored from the TimeStepInfo object (see replayAllStates) then the rewind manager re-executes the time steps (using the events stored at each timestep).

~RewindQueue()

RewindQueue::~RewindQueue

(

)

Frees all saved state information.

Note that the Rewinder data must be freed elsewhere.

Member Function Documentation

addLocalEvent()

void RewindQueue::addLocalEvent	(	EventRewinder *	event_rewinder,
		BareNetworkString *	buffer,
		bool	confirmed,
		int	ticks
	)

Adds an event to the rewind data.

The data to be stored must be allocated and not freed by the caller!

Parameters

buffer	Pointer to the event data.
ticks	Time at which the event happened.

addLocalState()

void RewindQueue::addLocalState	(	BareNetworkString *	buffer,
		bool	confirmed,
		int	ticks
	)

Adds a state from the local simulation to the last created TimeStepInfo container with the current world time.

It is not thread-safe, so needs to be called from the main thread.

Parameters

rewinder	The rewinder object for this state.
buffer	The state information.
confirmed	If this state is confirmed to be correct (e.g. is being received from the servrer), or just a local state for faster rewinds.
ticks	Time at which the event happened.

addNetworkEvent()

void RewindQueue::addNetworkEvent	(	EventRewinder *	event_rewinder,
		BareNetworkString *	buffer,
		int	ticks
	)

Adds an event to the list of network rewind data.

This function is threadsafe so can be called by the network thread. The data is synched to m_tRewindInformation list by the main thread. The data to be stored must be allocated and not freed by the caller!

Parameters

buffer	Pointer to the event data.
ticks	Time at which the event happened.

addNetworkState()

void RewindQueue::addNetworkState	(	BareNetworkString *	buffer,
		int	ticks
	)

Adds a state to the list of network rewind data.

This function is threadsafe so can be called by the network thread. The data is synched to RewindInfo list by the main thread. The data to be stored must be allocated and not freed by the caller!

Parameters

buffer	Pointer to the event data.
ticks	Time at which the event happened.

cleanupOldRewindInfo()

void RewindQueue::cleanupOldRewindInfo ( int  ticks )

private

Deletes all states and event before the given time.

Parameters

ticks

Time (in ticks).

getCurrent()

RewindInfo * RewindQueue::getCurrent ( )

inline

Returns the current RewindInfo.

Caller must make sure that there is at least one more RewindInfo (see hasMoreRewindInfo()).

insertRewindInfo()

void RewindQueue::insertRewindInfo

(

RewindInfo *

ri

)

Inserts a RewindInfo object in the list of all events at the correct time.

If there are several RewindInfo at the exact same time, state RewindInfo will be insert at the front, and event info at the end of the RewindInfo with the same time.

Parameters

ri	The RewindInfo object to insert.
update_current	If set, the current pointer will be updated if necessary to point to the new event

mergeNetworkData()

void RewindQueue::mergeNetworkData	(	int	world_ticks,
		bool *	needs_rewind,
		int *	rewind_ticks
	)

Merges thread-safe all data received from the network up to and including the current time (tick) with the current local rewind information.

Parameters

world_ticks[in]	Current world time up to which network events will be merged in.
needs_rewind[out]	True if a network event/state was received which was in the past (of this simulation), so a rewind must be performed.
rewind_time[out]	If needs_rewind is true, the time to which a rewind must be performed (at least). Otherwise undefined.

replayAllEvents()

void RewindQueue::replayAllEvents

(

int

ticks

)

Replays all events (not states) that happened at the specified time.

Parameters

ticks

Time in ticks.

undoUntil()

int RewindQueue::undoUntil

(

int

undo_ticks

)

Rewinds the rewind queue and undos all events/states stored.

It stops when the first confirmed state is reached that was recorded before the undo_time and sets the internal 'current' pointer to this state.

Parameters

undo_time

To what at least events need to be undone.

Returns

The time in ticks of the confirmed state

unitTesting()

void RewindQueue::unitTesting ( )

static

Unit tests for RewindQueue.

It tests:

• Sorting order of RewindInfos at the same time (i.e. state before time before events).
• Sorting order of RewindInfos with different timestamps (and a mixture of types).
• Special cases that triggered incorrect behaviour previously.

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

• network/rewind_queue.hpp
• network/rewind_queue.cpp