com.sap.tc.col.client.generic.api
Class LockStrategy

java.lang.Object
  |
  +--com.sap.tc.col.client.generic.api.LockStrategy

public class LockStrategy

extends java.lang.Object

Defines the available lock strategies supported in GCP. The four supported LockStrategies until now are:

• SHARED_PROMOTABLE_WITH_LOCK_PROMOTION_ON_UPDATE
• EXCLUSIVE
• SHARED_WITH_EXCLUSIVE_LOCK_ON_UPDATE
• SHARED_READ_ONLY

For locking the backend uses the Enqueue Server. With the Enqueue Server locking works with logical locks, not with physical locks assigned to database records, pages or tables like it works in most Data Base Management System.

The definition of the different strategies are: SHARED_PROMOTABLE_WITH_LOCK_PROMOTION_ON_UPDATE: GCP checks the supported lock modes of Aspect (meta data) and then

• if Aspect supports SP locks, a SP lock is acquired
• if Aspect supports E locks, an E lock is acquired
• otherwise an Exception is thrown

When a change request is received for an Aspect, which is locked with SP lock, the GCP promotes this SP lock to Exclusive. When a change request is received for an Aspect, which is already locked Exclusive, the GCP does no lock call. EXCLUSIVE: GCP checks the supported lock modes of Aspect (meta data) and then

• if Aspect supports E locks, an E lock is acquired
• otherwise an Exception is thrown

SHARED_WITH_EXCLUSIVE_LOCK_ON_UPDATE: GCP checks the supported lock modes of Aspect (meta data) and then

• if Aspect supports S and E locks, a S lock is acquired
• if Aspect supports E but not S locks, an E lock is acquired
• otherwise an Exception is thrown

When a change request is received for an Aspect, which is locked with S lock, the GCP promotes this S lock to Exclusive. When a change request is received for an Aspect, which is already locked Exclusive, the GCP does no lock call. SHARED_READ_ONLY: GCP checks the supported lock modes of Aspect (meta data) and then

• if Aspect supports S, a S lock is acquired
• otherwise an Exception is thrown

When a change request is received for an Aspect, which is locked with S lock, the GCP throws an Exception.

Field Summary

static LockStrategy	EXCLUSIVE
static LockStrategy	SHARED_PROMOTABLE_WITH_LOCK_PROMOTION_ON_UPDATE
static LockStrategy	SHARED_READ_ONLY
static LockStrategy	SHARED_WITH_EXCLUSIVE_LOCK_ON_UPDATE

Method Summary

java.lang.String	toString()
static LockStrategy	valueOf(java.lang.String description)

Methods inherited from class java.lang.Object

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

Field Detail

SHARED_PROMOTABLE_WITH_LOCK_PROMOTION_ON_UPDATE

public static final LockStrategy SHARED_PROMOTABLE_WITH_LOCK_PROMOTION_ON_UPDATE

EXCLUSIVE

public static final LockStrategy EXCLUSIVE

SHARED_WITH_EXCLUSIVE_LOCK_ON_UPDATE

public static final LockStrategy SHARED_WITH_EXCLUSIVE_LOCK_ON_UPDATE

SHARED_READ_ONLY

public static final LockStrategy SHARED_READ_ONLY

Method Detail

valueOf

public static LockStrategy valueOf(java.lang.String description)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object