* Immutable. Supports persistence using {@link java.beans.XMLEncoder}. * * @see Aggregation * @author Tom Erickson */ public final class AggregationRecord implements Record, Serializable { static final long serialVersionUID = -4367614268579702616L; static { try { BeanInfo info = Introspector.getBeanInfo(AggregationRecord.class); PersistenceDelegate persistenceDelegate = new DefaultPersistenceDelegate( new String[] {"tuple", "value", "ordinal"}) { /* * Need to prevent DefaultPersistenceDelegate from using * overridden equals() method, resulting in a * StackOverFlowError. Revert to PersistenceDelegate * implementation. See * http://forum.java.sun.com/thread.jspa?threadID= * 477019&tstart=135 */ protected boolean mutatesTo(Object oldInstance, Object newInstance) { return (newInstance != null && oldInstance != null && oldInstance.getClass() == newInstance.getClass()); } }; BeanDescriptor d = info.getBeanDescriptor(); d.setValue("persistenceDelegate", persistenceDelegate); } catch (IntrospectionException e) { System.out.println(e); } } /** @serial */ private Tuple tuple; /** @serial */ private AggregationValue value; /** @serial */ private int ordinal; /** * Creates an aggregation record with the given key and value. * Supports XML persistence. * * @see #AggregationRecord(Tuple tupleKey, AggregationValue * recordValue, int n) */ public AggregationRecord(Tuple tupleKey, AggregationValue recordValue) { // // Called by native code, but public to support backwardly // compatible XML encoding. // tuple = tupleKey; value = recordValue; validate(); } /** * Creates an aggregation record with the given key, value, and * ordinal. Supports XML persistence. * * @param tupleKey aggregation tuple, may be empty (see {@link * Tuple#EMPTY}) to indicate that this record's value belongs to an * unkeyed aggregation declared without square brackets, for * example:
{@code @a = count();}
* @param recordValue aggregated value associated with the given
* tuple
* @param n ordinal from zero (first) to n-1 (last) within the
* {@link Aggregate} containing this record
* @throws NullPointerException if the given key or value is
* {@code null}
* @throws IllegalArgumentException if the given ordinal is negative
*/
public
AggregationRecord(Tuple tupleKey, AggregationValue recordValue, int n)
{
tuple = tupleKey;
value = recordValue;
ordinal = n;
validate();
}
private final void
validate()
{
if (tuple == null) {
throw new NullPointerException("key is null");
}
if (value == null) {
throw new NullPointerException("value is null");
}
if (ordinal < 0) {
throw new IllegalArgumentException("ordinal is negative");
}
}
/**
* Gets the multi-element key associated with {@link
* #getValue()}.
*
* @return non-null, possibly empty tuple
* @see Aggregation#getRecord(Tuple key)
*/
public Tuple
getTuple()
{
return tuple;
}
/**
* Gets the value associated with {@link #getTuple()}. Values
* generated by the DTrace actions {@code count()}, {@code sum()},
* {@code avg()}, {@code min()}, and {@code max()} are of type
* {@link Long}. Values generated by the DTrace actions {@code
* quantize(}) and {@code lquantize()} are of type {@link
* Distribution}.
*
* @return non-null value keyed to {@link #getTuple()}
*/
public AggregationValue
getValue()
{
return value;
}
/**
* Gets the ordinal generated when this AggregationRecord was added
* to its containing {@link Aggregate} by the native DTrace library,
* from zero (first) to n-1 (last). The sequence described by an
* aggregate's record ordinals reflects the setting of the {@link
* Option#aggsortkey aggsortkey}, {@link Option#aggsortkeypos
* aggsortkeypos}, {@link Option#aggsortpos aggsortpos}, and {@link
* Option#aggsortrev aggsortrev} DTrace options and matches the way
* that the records would be ordered by {@code dtrace(1M)}.
*
* @return non-negative ordinal from zero (first) to n-1 (last)
* within the {@code Aggregate} containing this record
* @see Aggregate#getOrderedRecords()
*/
public int
getOrdinal()
{
return ordinal;
}
/**
* Package level access; called by Aggregate
*/
void
setOrdinal(int n)
{
if (n < 0) {
throw new IllegalArgumentException("ordinal is negative");
}
ordinal = n;
}
/**
* Compares the specified object with this aggregation record for
* equality. Defines equality as having the same tuple and value.
*
* @return {@code true} if and only if the specified object is an
* {@code AggregationRecord} and both records have equal tuples as
* defined by {@link Tuple#equals(Object o)} and equal values as
* defined by the implementation of {@link AggregationValue}
*/
public boolean
equals(Object o)
{
if (o instanceof AggregationRecord) {
AggregationRecord r = (AggregationRecord)o;
return (tuple.equals(r.tuple) &&
value.equals(r.value));
}
return false;
}
/**
* Overridden to ensure that equal records have equal hash codes.
*/
@Override
public int
hashCode()
{
int hash = 17;
hash = (37 * hash) + tuple.hashCode();
hash = (37 * hash) + value.hashCode();
return hash;
}
private void
readObject(ObjectInputStream s)
throws IOException, ClassNotFoundException
{
s.defaultReadObject();
// Check class invariants
try {
validate();
} catch (Exception e) {
InvalidObjectException x = new InvalidObjectException(
e.getMessage());
x.initCause(e);
throw x;
}
}
/**
* Gets a string representation of this aggregation record useful
* for logging and not intended for display. The exact details of
* the representation are unspecified and subject to change, but the
* following format may be regarded as typical:
*
* class-name[property1 = value1, property2 = value2]
*