com.espertech.esper.epl.variable

Interface VariableService

All Known Implementing Classes:

VariableServiceImpl

public interface VariableService

Variables service for reading and writing variables, and for setting a version number for the current thread to consider variables for.

See implementation class for further details.

Method Summary

Modifier and Type	Method and Description
void	allocateVariableState(String variableName, int agentInstanceId, StatementExtensionSvcContext extensionServicesContext, boolean isRecoveringResilient)
void	checkAndWrite(String variableName, int agentInstanceId, Object newValue) Check type of the value supplied and writes the new variable value.
void	commit() Commits the variable outstanding changes.
void	createNewVariable(String optionalContextName, String variableName, String type, boolean constant, boolean array, boolean arrayOfPrimitive, Object value, EngineImportService engineImportService)
void	deallocateVariableState(String variableName, int agentInstanceId)
void	destroy()
VariableReader	getReader(String variableName, int agentInstanceIdAccessor) Returns a reader that provides access to variable values.
ConcurrentHashMap<Integer,VariableReader>	getReadersPerCP(String variableName)
ReadWriteLock	getReadWriteLock() Lock for use in atomic writes to the variable space.
VariableMetaData	getVariableMetaData(String variableName)
Map<String,VariableReader>	getVariableReadersNonCP() Returns a map of variable name and reader, for thread-safe iteration.
String	isContextVariable(String propertyName)
void	registerCallback(String variableName, int agentInstanceId, VariableChangeCallback variableChangeCallback) Registers a callback invoked when the variable is written with a new value.
void	removeVariableIfFound(String name) Removes a variable.
void	rollback() Rolls back the variable outstanding changes.
void	setLocalVersion() Sets the variable version that subsequent reads consider.
void	unregisterCallback(String variableName, int agentInstanceId, VariableChangeCallback variableChangeCallback) Removes a callback.
void	write(int variableNumber, int agentInstanceId, Object newValue) Writes a new variable value.

Method Detail

setLocalVersion

void setLocalVersion()

Sets the variable version that subsequent reads consider.

getReadWriteLock

ReadWriteLock getReadWriteLock()

Lock for use in atomic writes to the variable space.

Returns:

read write lock for external coordinated write

createNewVariable

void createNewVariable(String optionalContextName,
                       String variableName,
                       String type,
                       boolean constant,
                       boolean array,
                       boolean arrayOfPrimitive,
                       Object value,
                       EngineImportService engineImportService)
                throws VariableExistsException,
                       VariableTypeException

Throws:

VariableExistsException

VariableTypeException

getReader

VariableReader getReader(String variableName,
                         int agentInstanceIdAccessor)

Returns a reader that provides access to variable values. The reader considers the version currently set via setLocalVersion.

Parameters:

variableName - the variable that the reader should read

agentInstanceIdAccessor - agent instance id of accessor

Returns:

reader

registerCallback

void registerCallback(String variableName,
                      int agentInstanceId,
                      VariableChangeCallback variableChangeCallback)

Registers a callback invoked when the variable is written with a new value.

Parameters:

variableName - variable name

agentInstanceId - agent instance id

variableChangeCallback - a callback

unregisterCallback

void unregisterCallback(String variableName,
                        int agentInstanceId,
                        VariableChangeCallback variableChangeCallback)

Removes a callback.

Parameters:

variableName - variable name

agentInstanceId - agent instance id

variableChangeCallback - a callback

write

void write(int variableNumber,
           int agentInstanceId,
           Object newValue)

Writes a new variable value.

Must be followed by either a commit or rollback.

Parameters:

variableNumber - the index number of the variable to write (from VariableReader)

newValue - the new value

agentInstanceId - agent instance id

checkAndWrite

void checkAndWrite(String variableName,
                   int agentInstanceId,
                   Object newValue)

Check type of the value supplied and writes the new variable value.

Must be followed by either a commit or rollback.

Parameters:

variableName - variable name

agentInstanceId - agent instance id

newValue - the new value

commit

void commit()

Commits the variable outstanding changes.

rollback

void rollback()

Rolls back the variable outstanding changes.

getVariableReadersNonCP

Map<String,VariableReader> getVariableReadersNonCP()

Returns a map of variable name and reader, for thread-safe iteration.

Returns:

variable names and readers

getVariableMetaData

VariableMetaData getVariableMetaData(String variableName)

removeVariableIfFound

void removeVariableIfFound(String name)

Removes a variable.

Parameters:

name - to remove

destroy

void destroy()

isContextVariable

String isContextVariable(String propertyName)

allocateVariableState

void allocateVariableState(String variableName,
                           int agentInstanceId,
                           StatementExtensionSvcContext extensionServicesContext,
                           boolean isRecoveringResilient)

deallocateVariableState

void deallocateVariableState(String variableName,
                             int agentInstanceId)

getReadersPerCP

ConcurrentHashMap<Integer,VariableReader> getReadersPerCP(String variableName)