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package oracle.toplink.essentials.sequencing;
import java.util.Vector;
import java.io.Serializable;
import oracle.toplink.essentials.internal.sessions.AbstractSession;
import oracle.toplink.essentials.internal.databaseaccess.Platform;
import oracle.toplink.essentials.internal.databaseaccess.DatasourcePlatform;
import oracle.toplink.essentials.internal.databaseaccess.Accessor;
import oracle.toplink.essentials.exceptions.ValidationException;
/**
*
* Purpose: Define an interface for sequencing customization.
*
* Description: Customary sequencing behavior could be achieved by
* implementing this interface and passing the instance to
* DatabaseSession.getSequencingControl().setValueGenerationPolicy(..).
* TopLink internally uses the same method to set its default implementation
* of this interface, which provides native sequencing and table sequencing.
* Note that the following methods:
* shouldAcquireValueAfterInsert();
* shouldUsePreallocation();
* shouldUseSeparateConnection();
* shouldUseTransaction();
* are called only once - during creation of the sequencing object.
* Therefore during the lifetime of sequencing object these methods
* should return the same values as when called for the first time.
* If this is not true - resetSequencing (call SequencingControl.resetSequencing()).
*
* Responsibilities:
*
* - Define the APIs for customary sequencing.
*
* @see SequencingControl
*/
public abstract class Sequence implements Serializable, Cloneable {
// name
protected String name = "";
// preallocation size
protected int size = 50;
// owner platform
protected Platform platform;
protected int initialValue = 1;
// number of times onConnect was called - number of times onDisconnect was called
protected int depth;
public Sequence() {
super();
}
public Sequence(String name) {
this();
setName(name);
}
public Sequence(String name, int size) {
this();
setName(name);
setPreallocationSize(size);
}
public Sequence(String name, int size, int initialValue) {
this();
setName(name);
setPreallocationSize(size);
setInitialValue(initialValue);
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getPreallocationSize() {
return size;
}
public void setPreallocationSize(int size) {
this.size = size;
}
public int getInitialValue() {
return initialValue;
}
public void setInitialValue(int initialValue) {
this.initialValue = initialValue;
}
public Object clone() {
try {
Sequence clone = (Sequence)super.clone();
if (isConnected()) {
clone.depth = 1;
clone.onDisconnect(getDatasourcePlatform());
}
return clone;
} catch (Exception exception) {
throw new InternalError("Clone failed");
}
}
public boolean equals(Object obj) {
if (obj instanceof Sequence) {
return equalNameAndSize(this, (Sequence)obj);
} else {
return false;
}
}
public static boolean equalNameAndSize(Sequence seq1, Sequence seq2) {
if (seq1 == seq2) {
return true;
}
return seq1.getName().equals(seq2.getName()) && (seq1.getPreallocationSize() == seq2.getPreallocationSize());
}
protected void setDatasourcePlatform(Platform platform) {
this.platform = platform;
}
public Platform getDatasourcePlatform() {
return platform;
}
/**
* INTERNAL:
* Indicates whether sequencing value should be acquired after INSERT.
* Note that preallocation could be used only in case sequencing values
* should be acquired before insert (this method returns false).
* In default implementation, it is true for table sequencing and native
* sequencing on Oracle platform, false for native sequencing on other platforms.
*/
public abstract boolean shouldAcquireValueAfterInsert();
/**
* INTERNAL:
* Indicates whether several sequencing values should be acquired at a time
* and be kept by TopLink. This in only possible in case sequencing numbers should
* be acquired before insert (shouldAcquireValueAfterInsert()==false).
* In default implementation, it is true for table sequencing and native
* sequencing on Oracle platform, false for native sequencing on other platforms.
*/
public boolean shouldUsePreallocation() {
return !shouldAcquireValueAfterInsert();
}
/**
* INTERNAL:
* Indicates whether TopLink should internally call beginTransaction() before
* getGeneratedValue/Vector, and commitTransaction after.
* In default implementation, it is true for table sequencing and
* false for native sequencing.
*/
public abstract boolean shouldUseTransaction();
/**
* INTERNAL:
* Indicates whether existing attribute value should be overridden.
* This method is called in case an attribute mapped to PK of sequencing-using
* descriptor contains non-null value.
* @param seqName String is sequencing number field name
* @param existingValue Object is a non-null value of PK-mapped attribute.
*/
public abstract boolean shouldOverrideExistingValue(String seqName, Object existingValue);
/**
* INTERNAL:
* Indicates whether existing attribute value should be overridden.
* This method is called in case an attribute mapped to PK of sequencing-using
* descriptor contains non-null value.
* @param existingValue Object is a non-null value of PK-mapped attribute.
*/
public boolean shouldOverrideExistingValue(Object existingValue) {
return shouldOverrideExistingValue(getName(), existingValue);
}
/**
* INTERNAL:
* Return the newly-generated sequencing value.
* Used only in case preallocation is not used (shouldUsePreallocation()==false).
* Accessor may be non-null only in case shouldUseSeparateConnection()==true.
* Even in this case accessor could be null - if SequencingControl().shouldUseSeparateConnection()==false;
* Therefore in case shouldUseSeparateConnection()==true, implementation should handle
* both cases: use a separate connection if provided (accessor != null), or get by
* without it (accessor == null).
* @param accessor Accessor is a separate sequencing accessor (may be null);
* @param writeSession Session is a Session used for writing (either ClientSession or DatabaseSession);
* @param seqName String is sequencing number field name
*/
public abstract Object getGeneratedValue(Accessor accessor, AbstractSession writeSession, String seqName);
/**
* INTERNAL:
* Return the newly-generated sequencing value.
* Used only in case preallocation is not used (shouldUsePreallocation()==false).
* Accessor may be non-null only in case shouldUseSeparateConnection()==true.
* Even in this case accessor could be null - if SequencingControl().shouldUseSeparateConnection()==false;
* Therefore in case shouldUseSeparateConnection()==true, implementation should handle
* both cases: use a separate connection if provided (accessor != null), or get by
* without it (accessor == null).
* @param accessor Accessor is a separate sequencing accessor (may be null);
* @param writeSession Session is a Session used for writing (either ClientSession or DatabaseSession);
*/
public Object getGeneratedValue(Accessor accessor, AbstractSession writeSession) {
return getGeneratedValue(accessor, writeSession, getName());
}
/**
* INTERNAL:
* Return a Vector of newly-generated sequencing values.
* Used only in case preallocation is used (shouldUsePreallocation()==true).
* Accessor may be non-null only in case shouldUseSeparateConnection()==true.
* Even in this case accessor could be null - if SequencingControl().shouldUseSeparateConnection()==false;
* Therefore in case shouldUseSeparateConnection()==true, implementation should handle
* both cases: use a separate connection if provided (accessor != null), or get by
* without it (accessor == null).
* @param accessor Accessor is a separate sequencing accessor (may be null);
* @param writeSession Session is a Session used for writing (either ClientSession or DatabaseSession);
* @param seqName String is sequencing number field name
* @param size int number of values to preallocate (output Vector size).
*/
public abstract Vector getGeneratedVector(Accessor accessor, AbstractSession writeSession, String seqName, int size);
/**
* INTERNAL:
* Return a Vector of newly-generated sequencing values.
* Used only in case preallocation is used (shouldUsePreallocation()==true).
* Accessor may be non-null only in case shouldUseSeparateConnection()==true.
* Even in this case accessor could be null - if SequencingControl().shouldUseSeparateConnection()==false;
* Therefore in case shouldUseSeparateConnection()==true, implementation should handle
* both cases: use a separate connection if provided (accessor != null), or get by
* without it (accessor == null).
* @param accessor Accessor is a separate sequencing accessor (may be null);
* @param writeSession Session is a Session used for writing (either ClientSession or DatabaseSession);
*/
public Vector getGeneratedVector(Accessor accessor, AbstractSession writeSession) {
return getGeneratedVector(accessor, writeSession, getName(), getPreallocationSize());
}
/**
* INTERNAL:
* This method is called when Sequencing object is created.
* Don't override this method.
* @param ownerSession DatabaseSession
*/
public void onConnect(Platform platform) {
if (isConnected()) {
verifyPlatform(platform);
} else {
setDatasourcePlatform(platform);
onConnect();
}
depth++;
}
/**
* INTERNAL:
* This method is called when Sequencing object is created.
* If it requires initialization, subclass should override this method.
* @param ownerSession DatabaseSession
*/
protected abstract void onConnect();
/**
* INTERNAL:
* This method is called when Sequencing object is destroyed.
* Don't overridethis method.
*/
public void onDisconnect(Platform platform) {
if (isConnected()) {
depth--;
if (depth == 0) {
onDisconnect();
setDatasourcePlatform(null);
}
}
}
/**
* INTERNAL:
* This method is called when Sequencing object is destroyed.
* If it requires deinitialization, subclass should override this method.
*/
protected abstract void onDisconnect();
/**
* PUBLIC:
* Indicates that Sequence is connected.
*/
public boolean isConnected() {
return platform != null;
}
/**
* INTERNAL:
* Make sure that the sequence is not used by more than one platform.
*/
protected void verifyPlatform(Platform otherPlatform) {
if (getDatasourcePlatform() != otherPlatform) {
String hashCode1 = Integer.toString(System.identityHashCode(getDatasourcePlatform()));
String name1 = ((DatasourcePlatform)getDatasourcePlatform()).toString() + '(' + hashCode1 + ')';
String hashCode2 = Integer.toString(System.identityHashCode(otherPlatform));
String name2 = ((DatasourcePlatform)otherPlatform).toString() + '(' + hashCode2 + ')';
throw ValidationException.sequenceCannotBeConnectedToTwoPlatforms(getName(), name1, name2);
}
}
}