org.apache.ignite.internal

Interface GridKernalGateway

All Known Implementing Classes:

GridKernalGatewayImpl

@GridToStringExclude
public interface GridKernalGateway

This interface guards access to implementations of public methods that access kernal functionality from the following main API interfaces:

• ClusterGroup

Note that this kernal gateway should not be used to guard against method from the following non-rich interfaces since their implementations are already managed by their respective implementing classes:

• Ignite
• ClusterNode

Kernal gateway is also responsible for notifying various futures about the change in kernal state so that issued futures could properly interrupt themselves when kernal becomes unavailable while future is held externally by the user.

Method Summary

Methods

Modifier and Type	Method and Description
void	addStopListener(Runnable lsnr) Adds stop listener.
GridKernalState	getState() Gets current kernal state.
void	lightCheck() Performs light-weight check on the kernal state at the moment of this call.
void	readLock() Should be called on entering every kernal related call originated directly or indirectly via public API.
void	readLockAnyway() Same as readLock() but doesn't throw IllegalStateException if grid stop.
void	readUnlock() Should be called on leaving every kernal related call originated directly or indirectly via public API.
void	removeStopListener(Runnable lsnr) Removes previously added stop listener.
void	setState(GridKernalState state) Sets kernal state.
boolean	tryWriteLock(long timeout)
String	userStackTrace() Gets user stack trace through the first call of grid public API.
void	writeLock() This method waits for all current calls to exit and blocks any further readLock() calls until writeUnlock() method is called.
void	writeUnlock() This method unblocks writeLock().

Method Detail

lightCheck

void lightCheck()
                throws IllegalStateException

Performs light-weight check on the kernal state at the moment of this call.

This method should only be used when the kernal state should be checked just once at the beginning of the method and the fact that kernal state can change in the middle of such method's execution should not matter.

For example, when a method returns a constant value its implementation doesn't depend on the kernal being valid throughout its execution. In such case it is enough to check the kernal's state just once at the beginning of this method to provide consistent behavior of the API without incurring overhead of lock-based guard methods.

Throws:

IllegalStateException - Thrown in case when no kernal calls are allowed.

readLock

void readLock()
              throws IllegalStateException

Should be called on entering every kernal related call originated directly or indirectly via public API.

This method essentially acquires a read lock and multiple threads can enter the call without blocking.

Throws:

IllegalStateException - Thrown in case when no kernal calls are allowed.

See Also:

readUnlock()

readLockAnyway

void readLockAnyway()

Same as readLock() but doesn't throw IllegalStateException if grid stop.

setState

void setState(GridKernalState state)

Sets kernal state. Various kernal states drive the logic inside of the gateway.

Parameters:

state - Kernal state to set.

getState

GridKernalState getState()

Gets current kernal state.

Returns:

Kernal state.

readUnlock

void readUnlock()

Should be called on leaving every kernal related call originated directly or indirectly via public API.

This method essentially releases the internal read-lock acquired previously by readLock() method.

See Also:

readLock()

writeLock

void writeLock()

This method waits for all current calls to exit and blocks any further readLock() calls until writeUnlock() method is called.

This method essentially acquires the internal write lock.

writeUnlock

void writeUnlock()

This method unblocks writeLock().

This method essentially releases internal write lock previously acquired by writeLock() method.

addStopListener

void addStopListener(Runnable lsnr)

Adds stop listener. Note that the identity set will be used to store listeners for performance reasons. Futures can register a listener to be notified when they need to be internally interrupted.

Parameters:

lsnr - Listener to add.

removeStopListener

void removeStopListener(Runnable lsnr)

Removes previously added stop listener.

Parameters:

lsnr - Listener to remove.

userStackTrace

String userStackTrace()

Gets user stack trace through the first call of grid public API.

tryWriteLock

boolean tryWriteLock(long timeout)
                     throws InterruptedException

Parameters:

timeout - Timeout.

Returns:

True if write lock has been acquired.

Throws:

InterruptedException - If interrupted.