de.ipcon.db.castor

Class AsyncCastorPersistenceQueryResults

java.lang.Object

de.ipcon.db.castor.CastorPersistenceQueryResults

de.ipcon.db.castor.AsyncCastorPersistenceQueryResults

All Implemented Interfaces:

de.ipcon.db.core.QueryResultsI, java.io.Closeable, java.lang.AutoCloseable, java.util.Iterator

public class AsyncCastorPersistenceQueryResults
extends CastorPersistenceQueryResults

An asynchronous, high-throughput implementation of CastorPersistenceQueryResults.

This implementation utilizes a Producer-Consumer pattern to decouple database fetching from OQL filtering and delivery from the main application thread. By pre-filling a bounded cache in the background, it effectively masks I/O latency and ORM mapping overhead (hydration etc.).

Throughput Optimizations:

• Overlapped I/O: Fetches the next batch while the consumer fetches and processes the current BO.
• Deterministic Back-pressure: Uses a bounded ArrayBlockingQueue to prevent uncontrolled heap growth if the consumer processing lags behind the database producer.
• Off-thread Hydration and Filtering / Memory Reclamation: Relocates CPU-intensive object hydration and Predicate evaluation as well as the slim() calls for any filtered-out object to the background thread, flattening the main thread's CPU profile.
• Thread Safety: Handles clean shutdown and background exception propagation.

Thread Safety Warning: The underlying Castor QueryResults (rs) is not thread-safe. This class assumes exclusive ownership of the result set by the background producer thread once started.

Constructor Summary

Constructors

Constructor and Description
AsyncCastorPersistenceQueryResults(CastorPersistenceHandler ph, java.lang.String query, java.lang.Object[] parms, short mode, java.lang.String[] prefetchPaths) Initializes the asynchronous result set and prepares the background executor.

Method Summary

Modifier and Type	Method and Description
void	close() Closes the underlying result set and the query implementation.
boolean	hasNext() Determines if a subsequent record is available, respecting any CastorPersistenceQueryResults.filterPredicate applied during OQL compilation.
java.lang.Object	next() Throughput Optimization: Memory Management: For read-only transactions, the previous BO is aggressively slimmed before fetching the next to prevent Heap bloat.

Methods inherited from class de.ipcon.db.castor.CastorPersistenceQueryResults

cancel, currentTag, isClosed, remove

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface de.ipcon.db.core.QueryResultsI

spliterator, stream

Methods inherited from interface java.util.Iterator

forEachRemaining

Constructor Detail

AsyncCastorPersistenceQueryResults

public AsyncCastorPersistenceQueryResults(CastorPersistenceHandler ph,
                                          java.lang.String query,
                                          java.lang.Object[] parms,
                                          short mode,
                                          java.lang.String[] prefetchPaths)

Initializes the asynchronous result set and prepares the background executor.

Method Detail

hasNext

public boolean hasNext()

Determines if a subsequent record is available, respecting any CastorPersistenceQueryResults.filterPredicate applied during OQL compilation.

Optimization Logic:

• Fast Path: If no filter is present, it delegates directly to the underlying ResultSet.
• Look-ahead: If a filter is present, it triggers a recursive fetch to find the next record that satisfies the predicate, caching the result in nextFittingBO.
• Inlining: Exception handling is streamlined via multi-catch to keep the method bytecode compact for JIT optimization.

Checks the background health and polls the prefetch cache.

Specified by:

hasNext in interface java.util.Iterator

Overrides:

hasNext in class CastorPersistenceQueryResults

Returns:

true if a subsequent call to CastorPersistenceQueryResults.next() is guaranteed to return a BO.

next

public java.lang.Object next()

Description copied from class: CastorPersistenceQueryResults

Throughput Optimization:

• Memory Management: For read-only transactions, the previous BO is aggressively slimmed before fetching the next to prevent Heap bloat.
• Look-ahead Pipeline: Implements a single-element buffer for filtered queries to ensure O(1) retrieval after hasNext().
• Exception Flattening: Uses multi-catch to reduce method bytecode size.

Specified by:

next in interface java.util.Iterator

Overrides:

next in class CastorPersistenceQueryResults

close

public void close()

Closes the underlying result set and the query implementation.

In addition to resource cleanup, this method "slims" any currently held Business Objects to aid memory reclamation and notifies the handler of query performance metrics via ph.complainSlowQuery.

Shuts down the background thread and clears the prefetch cache.

Specified by:

close in interface de.ipcon.db.core.QueryResultsI

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Overrides:

close in class CastorPersistenceQueryResults