/**
* This DBObjectDeltaRec constructor is used to generate a delta record that records the
* difference between two objects for the Ganymede journal
*/
public DBObjectDeltaRec(DBObject oldObj, DBObject newObj) {
if (oldObj == null || newObj == null) {
throw new IllegalArgumentException(
"Got a null object parameter"
+ ((oldObj == null) ? " old " : "")
+ ((newObj == null) ? " new " : ""));
}
if (!oldObj.getInvid().equals(newObj.getInvid())) {
throw new IllegalArgumentException("Old and New object id's don't match");
}
/* - */
this.invid = oldObj.getInvid();
DBObjectBase objectBase = oldObj.getBase();
DBField origField, currentField;
/* -- */
// algorithm: iterate over base.getFieldsInFieldOrder() to find
// all fields possibly contained in the object.. for each field,
// check to see if the value has changed. if so, create a
// fieldDeltaRec for it.
// note that we're counting on objectBase.sortedFields not being
// changed while we're iterating here.. this is an ok assumption,
// since only the loader and the schema editor will trigger changes
// in sortedFields.
if (debug) {
System.err.println(
"Entering deltarec creation for objects "
+ oldObj.getLabel()
+ " and "
+ newObj.getLabel());
}
for (DBObjectBaseField fieldDef : objectBase.getFieldsInFieldOrder()) {
if (debug) {
System.err.println("Comparing field " + fieldDef.getName());
}
origField = (DBField) oldObj.getField(fieldDef.getID());
currentField = (DBField) newObj.getField(fieldDef.getID());
if ((origField == null || !origField.isDefined())
&& (currentField == null || !currentField.isDefined())) {
// no change.. was null/undefined, still is.
continue;
}
if (currentField == null || !currentField.isDefined()) {
// lost this field
fieldRecs.addElement(new fieldDeltaRec(fieldDef.getID(), null));
continue;
}
if (origField == null || !origField.isDefined()) {
// we gained this field
fieldRecs.addElement(new fieldDeltaRec(fieldDef.getID(), currentField));
continue;
}
if (currentField.equals(origField)) {
// no changes, we don't need to write this one out.
continue;
}
// at this point, we know we need to write out a change
// record.. the only question now is whether it is for a
// scalar or a vector.
if (!fieldDef.isArray()) {
// got a scalar.. save this field entire to write out
// when we emit to the journal
fieldRecs.addElement(new fieldDeltaRec(fieldDef.getID(), currentField));
continue;
}
// it's a vector.. use the DBField.getVectorDiff() method
// to generate a vector diff.
fieldRecs.addElement(currentField.getVectorDiff(origField));
}
}
/**
* This method takes an object in its original state, and returns a new copy of the object with
* the changes embodied in this DBObjectDeltaRec applied to it.
*/
public DBObject applyDelta(DBObject original) {
if (!original.getInvid().equals(invid)) {
throw new IllegalArgumentException("Error, object identity mismatch");
}
/* - */
DBObject copy;
fieldDeltaRec fieldRec;
Object value;
/* -- */
copy = new DBObject(original, null);
// now process the fieldDeltaRec's.
for (int i = 0; i < fieldRecs.size(); i++) {
fieldRec = (fieldDeltaRec) fieldRecs.elementAt(i);
// are we clearing this field?
if (!fieldRec.vector && fieldRec.scalarValue == null) {
copy.clearField(fieldRec.fieldcode);
continue;
}
// are we doing a replace or add?
if (!fieldRec.vector) {
fieldRec.scalarValue.setOwner(copy);
if (copy.getField(fieldRec.fieldcode) != null) {
copy.replaceField(fieldRec.scalarValue);
} else {
copy.addField(fieldRec.scalarValue);
}
continue;
}
// ok, we must be doing a vector mod
// remember that we are intentionally bypassing the DBField's
// add/remove logic, as we assume that this DBObjectDeltaRec
// was generated as a result of a properly checked operation.
// Also, since we know that only string, invid, and IP fields
// can be vectors, we don't have to worry about the password
// and permission matrix special-case logic.
DBField field = copy.retrieveField(fieldRec.fieldcode);
if (fieldRec.addValues != null) {
for (int j = 0; j < fieldRec.addValues.size(); j++) {
value = fieldRec.addValues.elementAt(j);
if (value instanceof IPwrap) {
value = ((IPwrap) value).address;
}
field.getVectVal().addElement(value);
}
}
if (fieldRec.delValues != null) {
for (int j = 0; j < fieldRec.delValues.size(); j++) {
value = fieldRec.delValues.elementAt(j);
if (value instanceof IPwrap) {
value = ((IPwrap) value).address;
}
field.getVectVal().removeElement(value);
}
}
}
return copy;
}
