ThreadControlQueue Class Reference

Queue of paths to be processed by the system. More...

Detailed Description

Queue of paths to be processed by the system.

Classes
class	QueueTerminationException

Public Member Functions
	ThreadControlQueue (int numReceivers)
	Create a new queue with the specified number of receivers. More...
void	Block ()
	Block queue, all calls to Pop will block until Unblock is called. More...
void	Lock ()
	Aquires a lock on this queue. More...
Path	Pop ()
	Pops the next item off the queue. More...
Path	PopNoBlock (bool blockedBefore)
	Pops the next item off the queue, this call will not block. More...
void	Push (Path path)
	Push a path to the end of the queue. More...
void	PushFront (Path path)
	Push a path to the front of the queue. More...
void	ReceiverTerminated ()
	Call when a receiver was terminated in other ways than by a QueueTerminationException. More...
void	TerminateReceivers ()
	All calls to Pop and PopNoBlock will now generate exceptions. More...
void	Unblock ()
	Unblock queue. More...
void	Unlock ()
	Releases the lock on this queue. More...

Properties
bool	AllReceiversBlocked [get]
	True if blocking and all receivers are waiting for unblocking. More...
bool	IsEmpty [get]
	True if the queue is empty. More...
bool	IsTerminating [get]
	True if TerminateReceivers has been called. More...

Private Member Functions
void	Starving ()

Private Attributes
ManualResetEvent	block = new ManualResetEvent(true)
bool	blocked
int	blockedReceivers
	Number of receiver threads that are currently blocked. More...
Path	head
readonly System.Object	lockObj = new System.Object()
readonly int	numReceivers
bool	starving
	True while head == null. More...
Path	tail
bool	terminate
	True after TerminateReceivers has been called. More...

Constructor & Destructor Documentation

ThreadControlQueue()

ThreadControlQueue

(

int

numReceivers

)

Create a new queue with the specified number of receivers.

It is important that the number of receivers is fixed. Properties like AllReceiversBlocked rely on knowing the exact number of receivers using the Pop (or PopNoBlock) methods.

Member Function Documentation

Block()

void Block

(

)

Block queue, all calls to Pop will block until Unblock is called.

Lock()

void Lock

(

)

Aquires a lock on this queue.

Must be paired with a call to Unlock

Pop()

Path Pop

(

)

Pops the next item off the queue.

This call will block if there are no items in the queue or if the queue is currently blocked.

Returns

A Path object, guaranteed to be not null.

Exceptions

QueueTerminationException	if TerminateReceivers has been called.
System.InvalidOperationException	if more receivers get blocked than the fixed count sent to the constructor

PopNoBlock()

Path PopNoBlock

(

bool

blockedBefore

)

Pops the next item off the queue, this call will not block.

To ensure stability, the caller must follow this pattern. 1. Call PopNoBlock(false), if a null value is returned, wait for a bit (e.g yield return null in a Unity coroutine) 2. try again with PopNoBlock(true), if still null, wait for a bit 3. Repeat from step 2.

Exceptions

QueueTerminationException	if TerminateReceivers has been called.
System.InvalidOperationException	if more receivers get blocked than the fixed count sent to the constructor

Push()

void Push

(

Path

path

)

Push a path to the end of the queue.

PushFront()

void PushFront

(

Path

path

)

Push a path to the front of the queue.

ReceiverTerminated()

void ReceiverTerminated

(

)

Call when a receiver was terminated in other ways than by a QueueTerminationException.

After this call, the receiver should be dead and not call anything else in this class.

Starving()

void Starving ( )

private

TerminateReceivers()

void TerminateReceivers

(

)

All calls to Pop and PopNoBlock will now generate exceptions.

Unblock()

void Unblock

(

)

Unblock queue.

Calls to Pop will not block anymore.

See also

Block

Unlock()

void Unlock

(

)

Releases the lock on this queue.

Member Data Documentation

block

ManualResetEvent block = new ManualResetEvent(true)

private

blocked

bool blocked

private

blockedReceivers

int blockedReceivers

private

Number of receiver threads that are currently blocked.

This is only modified while a thread has a lock on lockObj

head

Path head

private

lockObj

readonly System.Object lockObj = new System.Object()

private

numReceivers

readonly int numReceivers

private

starving

bool starving

private

True while head == null.

This is only modified while a thread has a lock on lockObj

tail

Path tail

private

terminate

bool terminate

private

True after TerminateReceivers has been called.

All receivers will be terminated when they next call Pop.

Property Documentation

AllReceiversBlocked

bool AllReceiversBlocked

get

True if blocking and all receivers are waiting for unblocking.

IsEmpty

bool IsEmpty

get

True if the queue is empty.

IsTerminating

bool IsTerminating

get

True if TerminateReceivers has been called.

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

• /Users/arong/Unity/a-pathfinding-project/Assets/AstarPathfindingProject/Core/Misc/ThreadControlQueue.cs