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org.apache.derby.iapi.store.raw
Class ContainerKey  

java.lang.Object
  org.apache.derby.iapi.store.raw.ContainerKey

All Implemented Interfaces:

org.apache.derby.iapi.services.locks.Lockable, org.apache.derby.iapi.util.Matchable

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public final class ContainerKey

extends java.lang.Object

implements org.apache.derby.iapi.util.Matchable, org.apache.derby.iapi.services.locks.Lockable

A key that identifies a Container within the RawStore.
MT - Immutable

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Field Summary
private  long	containerId
private  long	segmentId

 

Constructor Summary

ContainerKey(long segmentId, long containerId)           Create a new ContainerKey

 

Method Summary
boolean	equals(java.lang.Object other)           Determine whether this Object is semantically equal to another Object.
long	getContainerId()           Return my identifier within the segment
long	getSegmentId()           Return my segment identifier
int	hashCode()           Get a value that represents this Object, as uniquely as possible within the confines of an int.
boolean	lockAttributes(int flag, java.util.Hashtable attributes)           This lockable wants to participate in the Virtual Lock table.
boolean	lockerAlwaysCompatible()           This method will only be called if requestCompatible returned false.
void	lockEvent(org.apache.derby.iapi.services.locks.Latch lockInfo)           Note the fact the object is locked.
boolean	match(java.lang.Object key)           Return true if the passed in object matches this object.
static ContainerKey	read(java.io.ObjectInput in)
boolean	requestCompatible(java.lang.Object requestedQualifier, java.lang.Object grantedQualifier)           Return true if the requested qualifier is compatible with the already granted qualifier.
java.lang.String	toString()           Convert this Object to a human-readable String.
void	unlockEvent(org.apache.derby.iapi.services.locks.Latch lockInfo)           Note that the object has been unlocked
void	writeExternal(java.io.ObjectOutput out)

 

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

 

Field Detail

segmentId

private final long segmentId

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containerId

private final long containerId

Constructor Detail

ContainerKey

public ContainerKey(long segmentId,
                    long containerId)

Create a new ContainerKey

Method Detail

getContainerId

public long getContainerId()

Return my identifier within the segment

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getSegmentId

public long getSegmentId()

Return my segment identifier

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writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

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read

public static ContainerKey read(java.io.ObjectInput in)
                         throws java.io.IOException

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equals

public boolean equals(java.lang.Object other)

Description copied from class: java.lang.Object

Determine whether this Object is semantically equal to another Object.

There are some fairly strict requirements on this method which subclasses must follow:

• It must be transitive. If a.equals(b) and b.equals(c), then a.equals(c) must be true as well.
• It must be symmetric. a.equals(b) and b.equals(a) must have the same value.
• It must be reflexive. a.equals(a) must always be true.
• It must be consistent. Whichever value a.equals(b) returns on the first invocation must be the value returned on all later invocations.
• a.equals(null) must be false.
• It must be consistent with hashCode(). That is, a.equals(b) must imply a.hashCode() == b.hashCode(). The reverse is not true; two objects that are not equal may have the same hashcode, but that has the potential to harm hashing performance.

This is typically overridden to throw a java.lang.ClassCastException if the argument is not comparable to the class performing the comparison, but that is not a requirement. It is legal for a.equals(b) to be true even though a.getClass() != b.getClass(). Also, it is typical to never cause a java.lang.NullPointerException.

In general, the Collections API (java.util) use the equals method rather than the == operator to compare objects. However, java.util.IdentityHashMap is an exception to this rule, for its own good reasons.

The default implementation returns this == o.

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hashCode

public int hashCode()

Description copied from class: java.lang.Object

Get a value that represents this Object, as uniquely as possible within the confines of an int.

There are some requirements on this method which subclasses must follow:

• Semantic equality implies identical hashcodes. In other words, if a.equals(b) is true, then a.hashCode() == b.hashCode() must be as well. However, the reverse is not necessarily true, and two objects may have the same hashcode without being equal.
• It must be consistent. Whichever value o.hashCode() returns on the first invocation must be the value returned on all later invocations as long as the object exists. Notice, however, that the result of hashCode may change between separate executions of a Virtual Machine, because it is not invoked on the same object.

Notice that since hashCode is used in java.util.Hashtable and other hashing classes, a poor implementation will degrade the performance of hashing (so don't blindly implement it as returning a constant!). Also, if calculating the hash is time-consuming, a class may consider caching the results.

The default implementation returns System.identityHashCode(this)

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toString

public java.lang.String toString()

Description copied from class: java.lang.Object

Convert this Object to a human-readable String. There are no limits placed on how long this String should be or what it should contain. We suggest you make it as intuitive as possible to be able to place it into System.out.println() 55 and such.

It is typical, but not required, to ensure that this method never completes abruptly with a java.lang.RuntimeException.

This method will be called when performing string concatenation with this object. If the result is null, string concatenation will instead use "null".

The default implementation returns getClass().getName() + "@" + Integer.toHexString(hashCode()).

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match

public boolean match(java.lang.Object key)

Description copied from interface: org.apache.derby.iapi.util.Matchable

Return true if the passed in object matches this object.

Specified by:

match in interface org.apache.derby.iapi.util.Matchable

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lockEvent

public void lockEvent(org.apache.derby.iapi.services.locks.Latch lockInfo)

Description copied from interface: org.apache.derby.iapi.services.locks.Lockable

Note the fact the object is locked. Performs required actions to ensure that unlockEvent() work correctly. This method does not actually perform any locking of the object, the locking mechanism is provided by the lock manager.

If the class supports multiple lockers of the object then this method will be called once per locker, each with their own qualifier.

Must only be called by the lock manager. Synchronization will be handled by the lock manager.

Specified by:

lockEvent in interface org.apache.derby.iapi.services.locks.Lockable

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requestCompatible

public boolean requestCompatible(java.lang.Object requestedQualifier,
                                 java.lang.Object grantedQualifier)

Description copied from interface: org.apache.derby.iapi.services.locks.Lockable

Return true if the requested qualifier is compatible with the already granted qualifier.

Specified by:

requestCompatible in interface org.apache.derby.iapi.services.locks.Lockable

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lockerAlwaysCompatible

public boolean lockerAlwaysCompatible()

This method will only be called if requestCompatible returned false. This results from two cases, some other compatabilty space has some lock that would conflict with the request, or this compatability space has a lock tha

Specified by:

lockerAlwaysCompatible in interface org.apache.derby.iapi.services.locks.Lockable

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unlockEvent

public void unlockEvent(org.apache.derby.iapi.services.locks.Latch lockInfo)

Description copied from interface: org.apache.derby.iapi.services.locks.Lockable

Note that the object has been unlocked

Must only be called by the lock manager. Synchronization will be handled by the lock manager.

Specified by:

unlockEvent in interface org.apache.derby.iapi.services.locks.Lockable

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lockAttributes

public boolean lockAttributes(int flag,
                              java.util.Hashtable attributes)

This lockable wants to participate in the Virtual Lock table.

Specified by:

lockAttributes in interface org.apache.derby.iapi.services.locks.Lockable

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