org.geotools.data

Class InProcessLockingManager

Object

InProcessLockingManager

All Implemented Interfaces:

LockingManager

public class InProcessLockingManager
extends Object
implements LockingManager

Provides In-Process FeatureLocking support for DataStore implementations.

If at all possible DataStore implementations should provide a real Feature Locking support that is persisted to disk or database and resepected by other processes.

This class provides a stop gap solution that implementations may use for GeoServer compatability.

Author:

Jody Garnett, Refractions Research, Chris Holmes, TOPP

TODO:

REVISIT: I'm not sure that the map within a map is a good idea, it makes things perhaps too complicated. A nasty bug came about with releasing, as allLocks put locks into a new collection, and the iterator just removed them from that set instead of from the storage. This is now fixed, but the loop to do it is really damn complex. I'm not sure of the solution, but there should be something that is less confusing.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	InProcessLockingManager.Lock Represents In-Process locks for Transactions or FeatureLocks.

Field Summary

Fields

Modifier and Type	Field and Description
protected Map	lockTables lockTable access by typeName stores Transactions or MemoryLocks

Constructor Summary

Constructors

Constructor and Description
InProcessLockingManager()

Method Summary

Modifier and Type	Method and Description
Set	allLocks() Set of all locks.
void	assertAccess(String typeName, String featureID, Transaction transaction) Checks mutability of featureID for this transaction.
FeatureWriter<SimpleFeatureType,SimpleFeature>	checkedWriter(FeatureWriter<SimpleFeatureType,SimpleFeature> writer, Transaction transaction) Provides a wrapper on the provided writer that checks locks.
protected InProcessLockingManager.Lock	createLock(Transaction transaction, FeatureLock featureLock) Creates the right sort of In-Process Lock.
boolean	exists(String authID) Implment lockExists.
protected InProcessLockingManager.Lock	getLock(String typeName, String featureID) Lock for typeName & featureID if it exists.
boolean	isLocked(String typeName, String featureID) Used by test cases
void	lockFeatureID(String typeName, String featureID, Transaction transaction, FeatureLock featureLock) Aquire lock on featureID.
Map	locks(String typeName) Access to a Map of locks for typeName
boolean	refresh(String authID, Transaction transaction) Refresh locks held by the authorization authID.
boolean	release(String authID, Transaction transaction) Release locks held by the authorization authID.
void	unLockFeatureID(String typeName, String featureID, Transaction transaction, FeatureLock featureLock) Release indicated featureID, must have correct authroization.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

lockTables

protected Map lockTables

lockTable access by typeName stores Transactions or MemoryLocks

Constructor Detail

InProcessLockingManager

public InProcessLockingManager()

Method Detail

lockFeatureID

public void lockFeatureID(String typeName,
                          String featureID,
                          Transaction transaction,
                          FeatureLock featureLock)
                   throws FeatureLockException

Aquire lock on featureID.

This method will fail if Lock is already held by another.

Specified by:

lockFeatureID in interface LockingManager

Parameters:

typeName - TypeName storing feature

featureID - FeatureID to lock

transaction - Transaction to lock against

featureLock - FeatureLock describing lock request

Throws:

FeatureLockException - Indicates a problem with the lock request

getLock

protected InProcessLockingManager.Lock getLock(String typeName,
                                               String featureID)

Lock for typeName & featureID if it exists.

This method will not return expired locks.

Parameters:

typeName -

featureID -

Returns:

Lock if exists, or null

createLock

protected InProcessLockingManager.Lock createLock(Transaction transaction,
                                                  FeatureLock featureLock)
                                           throws FeatureLockException

Creates the right sort of In-Process Lock.

Parameters:

transaction -

featureLock -

Returns:

In-Process Lock

Throws:

FeatureLockException - When a Transaction lock is requested against Transaction.AUTO_COMMIT

locks

public Map locks(String typeName)

Access to a Map of locks for typeName

Parameters:

typeName - typeName

Returns:

Map of Transaction or MemoryLock by featureID

allLocks

public Set allLocks()

Set of all locks.

Returns:

Set of all locks

assertAccess

public void assertAccess(String typeName,
                         String featureID,
                         Transaction transaction)
                  throws FeatureLockException

Checks mutability of featureID for this transaction.

Two behaviors are defined by FeatureLocking:

• TransactionLock (Blocking): lock held by a Transaction
  Authorization is granted to the Transaction holding the Lock. Conflict will result in a block until the Transaction holding the lock completes. (This behavior is equivalent to a Database row-lock, or a java synchronized statement)
• FeatureLock (Error): lock held by a FeatureLock
  Authorization is based on the set of Authorization IDs held by the provided Transaction. Conflict will result in an error. (This behavior is equivalent to the WFS locking specification)

Right now we are just going to error out with an exception

Parameters:

typeName - Feature type to check against

featureID - FeatureID to check

transaction - Provides Authorization

Throws:

FeatureLockException - If transaction does not have sufficient authroization

checkedWriter

public FeatureWriter<SimpleFeatureType,SimpleFeature> checkedWriter(FeatureWriter<SimpleFeatureType,SimpleFeature> writer,
                                                                    Transaction transaction)

Provides a wrapper on the provided writer that checks locks.

Parameters:

writer - FeatureWriter requiring access control

transaction - Transaction being used

Returns:

FeatureWriter with lock checking

unLockFeatureID

public void unLockFeatureID(String typeName,
                            String featureID,
                            Transaction transaction,
                            FeatureLock featureLock)
                     throws IOException

Release indicated featureID, must have correct authroization.

Specified by:

unLockFeatureID in interface LockingManager

Parameters:

typeName -

featureID -

transaction -

featureLock -

Throws:

IOException - If lock could not be released

refresh

public boolean refresh(String authID,
                       Transaction transaction)
                throws IOException

Refresh locks held by the authorization authID.

(remember that the lock may have expired)

Specified by:

refresh in interface LockingManager

Parameters:

authID - Authorization identifing Lock to refresh

transaction - Transaction with authorization for lockID

Returns:

true if lock was found and refreshed

Throws:

IOException - If transaction not authorized to refresh authID

IllegalArgumentException - If authID or transaction not provided

release

public boolean release(String authID,
                       Transaction transaction)
                throws IOException

Release locks held by the authorization authID.

(remember that the lock may have expired)

Specified by:

release in interface LockingManager

Parameters:

authID - Authorization identifing Lock to release

transaction - Transaction with authorization for lockID

Returns:

true if lock was found and released

Throws:

IOException - If transaction not authorized to release authID

IllegalArgumentException - If authID or transaction not provided

exists

public boolean exists(String authID)

Implment lockExists.

Remeber lock may have expired.

Specified by:

exists in interface LockingManager

Parameters:

authID -

Returns:

true if lock exists for authID

See Also:

org.geotools.data.LockingManager#lockExists(java.lang.String)

isLocked

public boolean isLocked(String typeName,
                        String featureID)

Used by test cases

Parameters:

typeName -

featureID -

Returns:

Return if feature is currently locked