org.jboss.cache.commands.read
Class ExistsCommand
java.lang.Object
org.jboss.cache.commands.read.AbstractDataCommand
org.jboss.cache.commands.read.ExistsCommand
- All Implemented Interfaces:
- Cloneable, DataCommand, ReplicableCommand, VisitableCommand
public class ExistsCommand
- extends AbstractDataCommand
Checks whether a given node exists in current in-memory state of the cache.
Does not acquire any locks in doing so (result may be dirty read). Does
not attempt to load nodes from a cache loader (may return false if a
node has been evicted).
Specifically used by the ClusteredCacheLoader
to
implement CacheLoader.exists(org.jboss.cache.Fqn)
This is the equivalent of the old MethodCallDefinitions.existsMethod method call from 2.1.x.
- Since:
- 2.2.0
- Author:
- Mircea.Markus@jboss.com
METHOD_ID
public static final int METHOD_ID
- See Also:
- Constant Field Values
ExistsCommand
public ExistsCommand(Fqn fqn)
ExistsCommand
public ExistsCommand()
perform
public Object perform(InvocationContext ctx)
- Checks whether a node represented by a given Fqn exists.
Deleted and invalid nodes are not considered.
- Parameters:
ctx
- invocation context
- Returns:
- true if the node exists, false otherwise.
acceptVisitor
public Object acceptVisitor(InvocationContext ctx,
Visitor visitor)
throws Throwable
- Description copied from interface:
VisitableCommand
- Accept a visitor, and return the result of accepting this visitor.
- Parameters:
ctx
- invocation contextvisitor
- visitor to accept
- Returns:
- arbitrary return value
- Throws:
Throwable
- in the event of problems
getCommandId
public int getCommandId()
- Description copied from interface:
ReplicableCommand
- Used by marshallers to convert this command into an id for streaming.
- Returns:
- the method id of this command. This is compatible with pre-2.2.0 MethodCall ids.
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