oracle.toplink.essentials.queryframework.DoesExistQuery Maven / Gradle / Ivy
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package oracle.toplink.essentials.queryframework;
import java.util.*;
import oracle.toplink.essentials.descriptors.ClassDescriptor;
import oracle.toplink.essentials.exceptions.*;
import oracle.toplink.essentials.internal.helper.*;
import oracle.toplink.essentials.internal.sessions.AbstractRecord;
import oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl;
import oracle.toplink.essentials.internal.sessions.AbstractSession;
/**
* Purpose:
* This should only be used by the descriptor, this should not be executed directly.
* Used to determine if an object resides on the database.
* DoesExistQuery is normally used to determine whether to make an update
* or insert statement when writing an object.
*
*
Responsibilities:
* Verify the existence of an object. Used only by a write object query.
*
* @author Yvon Lavoie
* @since TOPLink/Java 1.0
*/
public class DoesExistQuery extends DatabaseQuery {
public static final int AssumeNonExistence = 1;
public static final int AssumeExistence = 2;
public static final int CheckCache = 3;
public static final int CheckDatabase = 4;
/** Query that is performing the does exist check. */
protected Vector primaryKey;
protected Object object;
/** Flag to determine existence check policy. */
protected int existencePolicy;
/** Flag to determine cache invalidation policy support. This overrides
* checkcache existence settings if the object is set to be invalid or if
* the cache cannot be trusted
* */
protected boolean checkDatabaseIfInvalid;//default to true, allows users to override
/** Flag to get checkearlyreturn to override assume(non)existence and database checks with a cache check */
public boolean checkCacheFirst;//default to false, set in uow to true
/**
* PUBLIC:
* Initialize the state of the query .
* By default the cache is checked, if non cache is used the descriptor should throw a exception and validate.
*/
public DoesExistQuery() {
this.existencePolicy = CheckCache;
this.checkDatabaseIfInvalid = true;
this.checkCacheFirst = false;
}
/**
* PUBLIC:
* Create a query to check if the object exists.
*/
public DoesExistQuery(Object object) {
this();
this.object = object;
}
/**
* PUBLIC:
* Create a query to check if the object exists.
*/
public DoesExistQuery(Call call) {
this();
setCall(call);
}
/**
* PUBLIC:
* Assume that if the objects primary key does not include null then it must exist.
* This may be used if the user's system garentees that an object with non-null key exists.
*/
public void assumeExistenceForDoesExist() {
setExistencePolicy(AssumeExistence);
}
/**
* PUBLIC:
* Assume that the object does not exist.
* This may be used if the user's system garentees objects must always be inserted.
*/
public void assumeNonExistenceForDoesExist() {
setExistencePolicy(AssumeNonExistence);
}
/**
* PUBLIC:
* Assume that if the objects primary key does not include null
* and it is in the cache, then is must exist.
* This should only be used if a full identity map is being used,
* and a new object in the client cannot have been inserted by another client.
*/
public void checkCacheForDoesExist() {
setExistencePolicy(CheckCache);
}
/**
* PUBLIC:
* Perform does exist check on the database through slecting the primary key.
*/
public void checkDatabaseForDoesExist() {
setExistencePolicy(CheckDatabase);
}
/**
* INTERNAL:
* Check if existence can be determined without going to the database.
* Note that custom query check is not require for does exist as the custom is always used.
* Used by unit of work, and will return null if checkDatabaseIfInvalid is set and the cachekey is invalidated
*/
public Object checkEarlyReturn(Object object, Vector primaryKey, AbstractSession session, AbstractRecord translationRow) {
// For bug 3136413/2610803 building the selection criteria from an EJBQL string or
// an example object is done just in time.
buildSelectionCriteria(session);
ClassDescriptor descriptor = session.getDescriptor(object.getClass());
// Return false on null since it can't exist. Little more done incase PK not set in the query
if (object == null){
return Boolean.FALSE;
}else if (primaryKey == null) {
primaryKey = this.getPrimaryKey();
if ( primaryKey == null ){
primaryKey = descriptor.getObjectBuilder().extractPrimaryKeyFromObject(object, session);
}
}
if ((primaryKey == null)|| (primaryKey.contains(null)) ) {
return Boolean.FALSE;
}
//need to do the cache check first if flag set or if we should check the cache only for existence
if (shouldCheckCacheForDoesExist() ||(checkCacheFirst)) {
//if this is a UOW and modification queries have been executed, the cache cannot be trusted
if ( checkDatabaseIfInvalid && (session.isUnitOfWork() &&
((UnitOfWorkImpl)session).shouldReadFromDB() ) ){
return null;
}
oracle.toplink.essentials.internal.identitymaps.CacheKey cacheKey;
Class objectClass = object.getClass();
if (session.isUnitOfWork()){
cacheKey = session.getIdentityMapAccessorInstance().getCacheKeyForObject(primaryKey,objectClass, descriptor);
if (cacheKey!=null){ //if in the UOW cache, it exists and can't be invalid
return Boolean.TRUE;
}
cacheKey = ((UnitOfWorkImpl)session).getParent().getIdentityMapAccessorInstance().getCacheKeyForObject(primaryKey,objectClass, descriptor);
}else{
cacheKey = session.getIdentityMapAccessorInstance().getCacheKeyForObject(primaryKey,objectClass, descriptor);
}
if ((cacheKey !=null)){
//assume that if there is a cachekey, object exists
boolean invalid;
if ( checkDatabaseIfInvalid ){
long currentTimeInMillis = System.currentTimeMillis();
invalid = session.getDescriptor(objectClass).getCacheInvalidationPolicy().isInvalidated(cacheKey, currentTimeInMillis);
}else {
invalid = false;
}
if (!invalid){
Object objectFromCache = cacheKey.getObject();
if ((session instanceof oracle.toplink.essentials.internal.ejb.cmp3.base.RepeatableWriteUnitOfWork)&&
(((oracle.toplink.essentials.internal.ejb.cmp3.base.RepeatableWriteUnitOfWork)session).getUnregisteredDeletedCloneForOriginal(objectFromCache)!=null)){
//session.isUnitOfWork() && objectFromCache!=null && ((UnitOfWorkImpl)session).isObjectDeleted(objectFromCache)){
if(shouldCheckCacheForDoesExist()){
return Boolean.FALSE;
}
}else {
return Boolean.TRUE;
}
}else {
//We know it is invalid, and checkDatabaseIfInvalid policy so skip to the database
return null;
}
}else if(shouldCheckCacheForDoesExist()){
//We know its not in cache, and a checkcache policy so return false
return Boolean.FALSE;
}
}
// Check if we have to assume that the object does not exist.
if (shouldAssumeNonExistenceForDoesExist()) {
return Boolean.FALSE;
}
// Check to see if we only need to check that the object contains a primary key.
if (shouldAssumeExistenceForDoesExist()) {
return Boolean.TRUE;
}
return null;
}
/**
* INTERNAL:
* Check if existence can be determined without going to the database.
* Note that custom query check is not require for does exist as the custom is always used.
*/
public Object checkEarlyReturn(AbstractSession session, AbstractRecord translationRow) {
return checkEarlyReturn(getObject(), getPrimaryKey(), session, translationRow);
}
/**
* INTERNAL:
* Return if the object exists on the database.
* This must be a Boolean object to conform with returning an object.
* If using optimistic locking, check that the value matches.
* @exception DatabaseException - an error has occurred on the database.
*/
public Object executeDatabaseQuery() throws DatabaseException {
// Get the required fields for does exist check.
DatabaseField field = getDoesExistField();
// Get row from database
AbstractRecord databaseRow = getQueryMechanism().selectRowForDoesExist(field);
// Null means no row was returned.
return new Boolean(databaseRow != null);
}
/**
* INTERNAL:
* Return the write lock field or the first primary key field if not using locking.
*/
protected DatabaseField getDoesExistField() {
return (DatabaseField)(getDescriptor().getPrimaryKeyFields().get(0));
}
/**
* INTERNAL:
* Return the existence policy for this existence Query
*/
public int getExistencePolicy() {
return this.existencePolicy;
}
/**
* PUBLIC:
* Return the object.
*/
public Object getObject() {
return object;
}
/**
* INTERNAL:
* Return the primaryKey.
*/
public Vector getPrimaryKey() {
return primaryKey;
}
/**
* Return the domain class associated with this query.
*/
public Class getReferenceClass() {
return getObject().getClass();
}
/**
* INTERNAL:
* Return the name of the reference class for this query
* Note: Although the API is designed to avoid requirement of classes being on the classpath,
* this is not a user defined query type, so it is ok to access the class.
*/
public String getReferenceClassName() {
return getReferenceClass().getName();
}
/**
* INTERNAL:
* Prepare the receiver for execution in a session.
*/
protected void prepare() throws QueryException {
if (getDescriptor() == null) {
//Bug#3947714 Pass the object instead of class in case object is proxy
setDescriptor(getSession().getDescriptor(getObject()));
}
if (getObject() != null) {// Prepare can be called without the object set yet.
setObject(getDescriptor().getObjectBuilder().unwrapObject(getObject(), getSession()));
}
super.prepare();
// It will only get to prepare if check database if required.
getQueryMechanism().prepareDoesExist(getDoesExistField());
}
/**
* INTERNAL:
* Prepare the receiver for execution in a session.
*/
public void prepareForExecution() throws QueryException {
super.prepareForExecution();
if (getObject() == null) {
throw QueryException.objectToModifyNotSpecified(this);
}
setObject(getDescriptor().getObjectBuilder().unwrapObject(getObject(), getSession()));
if (getDescriptor() == null) {
setDescriptor(getSession().getDescriptor(getObject().getClass()));
}
if (getPrimaryKey() == null) {
setPrimaryKey(getDescriptor().getObjectBuilder().extractPrimaryKeyFromObject(getObject(), getSession()));
}
if ((getTranslationRow() == null) || (getTranslationRow().isEmpty())) {
setTranslationRow(getDescriptor().getObjectBuilder().buildRowForTranslation(getObject(), getSession()));
}
}
/**
* INTERNAL:
* Set if the existence policy, this must be set to one of the constants.
*/
public void setExistencePolicy(int existencePolicy) {
this.existencePolicy = existencePolicy;
}
/**
* PUBLIC:
* Set the object.
*/
public void setObject(Object object) {
this.object = object;
}
/**
* INTERNAL:
* Set the primaryKey.
*/
public void setPrimaryKey(Vector primaryKey) {
this.primaryKey = primaryKey;
}
/**
* PUBLIC:
* Returns true if the does exist check should be based only
* on whether the primary key of the object is set
*/
public boolean shouldAssumeExistenceForDoesExist() {
return existencePolicy == AssumeExistence;
}
/**
* PUBLIC:
* Returns true if the does exist check should assume non existence.
*/
public boolean shouldAssumeNonExistenceForDoesExist() {
return existencePolicy == AssumeNonExistence;
}
/**
* PUBLIC:
* Returns true if the does exist check should be based only
* on a cache check. Default behavior.
*/
public boolean shouldCheckCacheForDoesExist() {
return existencePolicy == CheckCache;
}
/**
* PUBLIC:
* Returns true if the does exist check should query the database.
*/
public boolean shouldCheckDatabaseForDoesExist() {
return existencePolicy == CheckDatabase;
}
/**
* INTERNAL:
* Sets checkCacheFirst flag. If true, existence check will first go to the
* cache. It will then check other options if it is not found in the cache
* @param checkCacheFirst
*/
public void setCheckCacheFirst(boolean checkCacheFirst){
this.checkCacheFirst = checkCacheFirst;
}
/**
* INTERNAL:
* @param checkCacheFirst
*/
public boolean getCheckCacheFirst(){
return this.checkCacheFirst;
}
/**
* INTERNAL:
* Sets checkDatabaseIfInvalid flag. If true, query will go to the
* database when it finds the object in the cache and it is invalid.
* This is only valid when it checks the cache, and is true by default
* @param checkDatabaseIfInvalid
*/
public void setCheckDatabaseIfInvalid(boolean checkCacheFirst){
this.checkCacheFirst = checkCacheFirst;
}
/**
* INTERNAL:
* @param checkDatabaseIfInvalid
*/
public boolean getCheckDatabaseIfInvalid(){
return this.checkCacheFirst;
}
}