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org.apache.derby.impl.services.locks
Class SinglePool  

java.lang.Object
  java.util.Dictionary
      java.util.Hashtable
          org.apache.derby.impl.services.locks.SinglePool

All Implemented Interfaces:

java.lang.Cloneable, org.apache.derby.iapi.services.locks.LockFactory, java.util.Map, org.apache.derby.iapi.services.property.PropertySetCallback, java.io.Serializable

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public class SinglePool

extends java.util.Hashtable

implements org.apache.derby.iapi.services.locks.LockFactory

An implementation of LockFactory that uses a single pool for the locks, i.e. all lock requests go through a single point of synchronisation.

The default concrete class "SinglePool.java", prints nothing and thus incurs no overhead associated with the code to dump lock information. An alternate concrete class "LockDebug/TracingSinglePool.java", attempts to output only lock information that "makes sense" to a user - for instance it doesn't print latch locks.
MT - Mutable - Container Object : Thread Aware

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Nested Class Summary

 

Nested classes inherited from class java.util.Hashtable

 

Nested classes inherited from class java.util.Map

java.util.Map.Entry

 

Field Summary
(package private)  int	deadlockMonitor           True if all deadlocks errors should be logged.
protected  LockSet	lockTable           The complete set of locks in the system MT - immutable - content dynamic : LockSet is ThreadSafe

 

Fields inherited from class java.util.Hashtable

 

Constructor Summary

SinglePool()

 

Method Summary
boolean	anyoneBlocked()           Returns true if locks by anyone are blocking anyone else
org.apache.derby.iapi.services.daemon.Serviceable	apply(java.lang.String key, java.io.Serializable value, java.util.Dictionary p)           Apply a property change.
boolean	areLocksHeld(java.lang.Object compatabilitySpace)           Return true if locks are held in this space MT - thread safe
boolean	areLocksHeld(java.lang.Object compatabilitySpace, java.lang.Object group)           Return true if locks are held in this group and this space.
void	clearLimit(java.lang.Object compatabilitySpace, java.lang.Object group)           Clear a limit set by setLimit.
private  void	getAndApply(boolean dbOnly, java.util.Dictionary p, java.lang.String key)
private static int	getWaitValue(java.lang.String value, int defaultValue)
void	init(boolean dbOnly, java.util.Dictionary p)           Initialize the properties for this callback.
boolean	isLockHeld(java.lang.Object compatabilitySpace, java.lang.Object group, org.apache.derby.iapi.services.locks.Lockable ref, java.lang.Object qualifier)           Check to see if a specific lock is held.
boolean	latchObject(java.lang.Object compatabilitySpace, org.apache.derby.iapi.services.locks.Lockable ref, java.lang.Object qualifier, int timeout)           Latch a specific object with a timeout.
protected  Lock	lockAnObject(java.lang.Object compatabilitySpace, java.lang.Object group, org.apache.derby.iapi.services.locks.Lockable ref, java.lang.Object qualifier, int timeout, org.apache.derby.iapi.services.locks.Latch heldLatch)           Lock a specific object with a timeout.
boolean	lockObject(java.lang.Object group, org.apache.derby.iapi.services.locks.Lockable ref, java.lang.Object qualifier, int timeout, org.apache.derby.iapi.services.locks.Latch latch)           Lock a specific object while holding a latch MT - thread safe
boolean	lockObject(java.lang.Object compatabilitySpace, java.lang.Object group, org.apache.derby.iapi.services.locks.Lockable ref, java.lang.Object qualifier, int timeout)           Lock a specific object MT - thread safe
java.util.Enumeration	makeVirtualLockTable()           Routines to support lock diagnostics VTIs for the benefit of VirtualLockTable
java.io.Serializable	map(java.lang.String key, java.io.Serializable value, java.util.Dictionary p)           Map a proposed new value for a property to an official value.
void	setLimit(java.lang.Object compatabilitySpace, java.lang.Object group, int limit, org.apache.derby.iapi.services.locks.Limit callback)           Install a limit that is called when the size of the group exceeds the required limit.
java.lang.String	toDebugString()
void	transfer(java.lang.Object compatabilitySpace, java.lang.Object oldGroup, java.lang.Object newGroup)           Transfer a set of locks from one group to another.
void	unlatch(org.apache.derby.iapi.services.locks.Latch heldLatch)           Unlatch an object.
int	unlock(java.lang.Object compatabilitySpace, java.lang.Object group, org.apache.derby.iapi.services.locks.Lockable ref, java.lang.Object qualifier)           Unlock a specific object MT - thread safe
void	unlockGroup(java.lang.Object compatabilitySpace, java.lang.Object group)           Unlock a group of objects.
void	unlockGroup(java.lang.Object compatabilitySpace, java.lang.Object group, org.apache.derby.iapi.util.Matchable key)           Unlock all locks on a group that match the passed in value.
boolean	validate(java.lang.String key, java.io.Serializable value, java.util.Dictionary p)           Validate a property change.
boolean	zeroDurationlockObject(java.lang.Object compatabilitySpace, org.apache.derby.iapi.services.locks.Lockable ref, java.lang.Object qualifier, int timeout)           Lock an object with zero duration within a compatability space, waits up to timeout milli-seconds for the object to become unlocked.

 

Methods inherited from class java.util.Hashtable

clear, clone, contains, containsKey, containsValue, elements, entrySet, equals, get, hashCode, isEmpty, keys, keySet, put, putAll, rehash, remove, size, toString, values

 

Methods inherited from class java.lang.Object

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

 

Field Detail

lockTable

protected final LockSet lockTable

The complete set of locks in the system
MT - immutable - content dynamic : LockSet is ThreadSafe

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deadlockMonitor

int deadlockMonitor

True if all deadlocks errors should be logged.

Constructor Detail

SinglePool

public SinglePool()

Method Detail

latchObject

public boolean latchObject(java.lang.Object compatabilitySpace,
                           org.apache.derby.iapi.services.locks.Lockable ref,
                           java.lang.Object qualifier,
                           int timeout)
                    throws org.apache.derby.iapi.error.StandardException

Latch a specific object with a timeout.
MT - thread safe

Specified by:

latchObject in interface org.apache.derby.iapi.services.locks.LockFactory

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unlatch

public void unlatch(org.apache.derby.iapi.services.locks.Latch heldLatch)

Unlatch an object.
MT - thread safe

Specified by:

unlatch in interface org.apache.derby.iapi.services.locks.LockFactory

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lockAnObject

protected Lock lockAnObject(java.lang.Object compatabilitySpace,
                            java.lang.Object group,
                            org.apache.derby.iapi.services.locks.Lockable ref,
                            java.lang.Object qualifier,
                            int timeout,
                            org.apache.derby.iapi.services.locks.Latch heldLatch)
                     throws org.apache.derby.iapi.error.StandardException

Lock a specific object with a timeout.
MT - thread safe

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lockObject

public boolean lockObject(java.lang.Object compatabilitySpace,
                          java.lang.Object group,
                          org.apache.derby.iapi.services.locks.Lockable ref,
                          java.lang.Object qualifier,
                          int timeout)
                   throws org.apache.derby.iapi.error.StandardException

Lock a specific object
MT - thread safe

Specified by:

lockObject in interface org.apache.derby.iapi.services.locks.LockFactory

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lockObject

public boolean lockObject(java.lang.Object group,
                          org.apache.derby.iapi.services.locks.Lockable ref,
                          java.lang.Object qualifier,
                          int timeout,
                          org.apache.derby.iapi.services.locks.Latch latch)
                   throws org.apache.derby.iapi.error.StandardException

Lock a specific object while holding a latch
MT - thread safe

Specified by:

lockObject in interface org.apache.derby.iapi.services.locks.LockFactory

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unlock

public int unlock(java.lang.Object compatabilitySpace,
                  java.lang.Object group,
                  org.apache.derby.iapi.services.locks.Lockable ref,
                  java.lang.Object qualifier)

Unlock a specific object
MT - thread safe

Specified by:

unlock in interface org.apache.derby.iapi.services.locks.LockFactory

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unlockGroup

public void unlockGroup(java.lang.Object compatabilitySpace,
                        java.lang.Object group)

Unlock a group of objects.
MT - thread safe

Specified by:

unlockGroup in interface org.apache.derby.iapi.services.locks.LockFactory

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unlockGroup

public void unlockGroup(java.lang.Object compatabilitySpace,
                        java.lang.Object group,
                        org.apache.derby.iapi.util.Matchable key)

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

Unlock all locks on a group that match the passed in value.

Specified by:

unlockGroup in interface org.apache.derby.iapi.services.locks.LockFactory

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transfer

public void transfer(java.lang.Object compatabilitySpace,
                     java.lang.Object oldGroup,
                     java.lang.Object newGroup)

Transfer a set of locks from one group to another.
MT - thread safe

Specified by:

transfer in interface org.apache.derby.iapi.services.locks.LockFactory

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anyoneBlocked

public boolean anyoneBlocked()

Returns true if locks by anyone are blocking anyone else

Specified by:

anyoneBlocked in interface org.apache.derby.iapi.services.locks.LockFactory

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areLocksHeld

public boolean areLocksHeld(java.lang.Object compatabilitySpace,
                            java.lang.Object group)

Return true if locks are held in this group and this space.
MT - thread safe

Specified by:

areLocksHeld in interface org.apache.derby.iapi.services.locks.LockFactory

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areLocksHeld

public boolean areLocksHeld(java.lang.Object compatabilitySpace)

Return true if locks are held in this space
MT - thread safe

Specified by:

areLocksHeld in interface org.apache.derby.iapi.services.locks.LockFactory

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zeroDurationlockObject

public boolean zeroDurationlockObject(java.lang.Object compatabilitySpace,
                                      org.apache.derby.iapi.services.locks.Lockable ref,
                                      java.lang.Object qualifier,
                                      int timeout)
                               throws org.apache.derby.iapi.error.StandardException

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

Lock an object with zero duration within a compatability space, waits up to timeout milli-seconds for the object to become unlocked. A timeout of 0 means do not wait for the lock to be unlocked. Note the actual time waited is approximate.

Zero duration means the lock is released as soon as it is obtained.

A compatibility space in an space where lock requests are assumed to be compatabile and granted by the lock manager if the trio {compatabilitySpace, ref, qualifier} are equal (i.e. reference equality for qualifier, equals() method for compatabilitySpace and ref ). A typical reference to use for the compatability space is a reference to an object representing a transaction. Granted by the lock manager means that the Lockable object may or may not be queried to see if the request is compatible.
A compatability space is not assumed to be owned by a single thread.

Specified by:

zeroDurationlockObject in interface org.apache.derby.iapi.services.locks.LockFactory

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isLockHeld

public boolean isLockHeld(java.lang.Object compatabilitySpace,
                          java.lang.Object group,
                          org.apache.derby.iapi.services.locks.Lockable ref,
                          java.lang.Object qualifier)

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

Check to see if a specific lock is held.

Specified by:

isLockHeld in interface org.apache.derby.iapi.services.locks.LockFactory

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setLimit

public void setLimit(java.lang.Object compatabilitySpace,
                     java.lang.Object group,
                     int limit,
                     org.apache.derby.iapi.services.locks.Limit callback)

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

Install a limit that is called when the size of the group exceeds the required limit.
It is not guaranteed that the callback method (Limit.reached) is called as soon as the group size exceeds the given limit. If the callback method does not result in a decrease in the number of locks held then the lock factory implementation may delay calling the method again. E.g. with a limit of 500 and a reached() method that does nothing, may result in the call back method only being called when the group size reaches 550.
Only one limit may be in place for a group at any time.

Specified by:

setLimit in interface org.apache.derby.iapi.services.locks.LockFactory

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clearLimit

public void clearLimit(java.lang.Object compatabilitySpace,
                       java.lang.Object group)

Clear a limit set by setLimit.

Specified by:

clearLimit in interface org.apache.derby.iapi.services.locks.LockFactory

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makeVirtualLockTable

public java.util.Enumeration makeVirtualLockTable()

Routines to support lock diagnostics VTIs for the benefit of VirtualLockTable

Specified by:

makeVirtualLockTable in interface org.apache.derby.iapi.services.locks.LockFactory

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toDebugString

public java.lang.String toDebugString()

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init

public void init(boolean dbOnly,
                 java.util.Dictionary p)

Description copied from interface: org.apache.derby.iapi.services.property.PropertySetCallback

Initialize the properties for this callback. Called when addPropertySetNotification() is called with a non-null transaction controller. This allows code to set read its initial property values at boot time.

Code within an init() method should use the 3 argument PropertyUtil method getPropertyFromSet() to obtain a property's value.

Specified by:

init in interface org.apache.derby.iapi.services.property.PropertySetCallback

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getAndApply

private void getAndApply(boolean dbOnly,
                         java.util.Dictionary p,
                         java.lang.String key)

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validate

public boolean validate(java.lang.String key,
                        java.io.Serializable value,
                        java.util.Dictionary p)
                 throws org.apache.derby.iapi.error.StandardException

Description copied from interface: org.apache.derby.iapi.services.property.PropertySetCallback

Validate a property change.

Specified by:

validate in interface org.apache.derby.iapi.services.property.PropertySetCallback

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apply

public org.apache.derby.iapi.services.daemon.Serviceable apply(java.lang.String key,
                                                               java.io.Serializable value,
                                                               java.util.Dictionary p)
                                                        throws org.apache.derby.iapi.error.StandardException

Description copied from interface: org.apache.derby.iapi.services.property.PropertySetCallback

Apply a property change. Will only be called after validate has been called and only if validate returned true. If this method is called then the new value is the value to be used, ie. the property is not set in the overriding JVM system set.

Specified by:

apply in interface org.apache.derby.iapi.services.property.PropertySetCallback

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map

public java.io.Serializable map(java.lang.String key,
                                java.io.Serializable value,
                                java.util.Dictionary p)

Description copied from interface: org.apache.derby.iapi.services.property.PropertySetCallback

Map a proposed new value for a property to an official value. Will only be called after apply() has been called.

Specified by:

map in interface org.apache.derby.iapi.services.property.PropertySetCallback

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getWaitValue

private static int getWaitValue(java.lang.String value,
                                int defaultValue)

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Overview  Package   Class  Use  Deprecated  Index
Home >> All >> org >> apache >> derby >> impl >> services >> [ locks overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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